KR102707124B1 - Resist composition and method of forming resist pattern - Google Patents

Abstract

(Problem) To provide a resist composition having excellent lithography characteristics, good applicability, and suppression of foaming from the resist pattern during high-temperature baking, particularly when forming a resist pattern by depositing a thick resist film.
(Solution) A resist composition containing a polymer compound having a structural unit represented by formula (a10-1) and a structural unit including an acid-decomposable group whose polarity increases by the action of an acid, and an acid generator represented by formula (b1), and having a solid content concentration of 30 mass% or more. In formula (a10-1), R is a hydrogen atom, an alkyl group, or a halogenated alkyl group. Ya ^x1 is a single bond or a divalent linking group. Wa ^x1 is an aromatic hydrocarbon group. n _ax1 is an integer of 1 to 3. In formula (b1), R ²⁰¹¹ , R ²⁰²¹ , and R ²⁰³¹ represent an aryl group, and two or more of them may be bonded to each other to form a ring together with the sulfur atom in the formula. X ^- represents a counter anion.
[Chemical Formula 1]

Description

{RESIST COMPOSITION AND METHOD OF FORMING RESIST PATTERN}

The present invention relates to a resist composition and a method for forming a resist pattern.

In lithography technology, for example, a process is carried out in which a resist film made of a resist material is formed on a substrate, selective exposure is performed on the resist film, and development is performed to form a resist pattern of a predetermined shape on the resist film. A resist material in which the exposed portion of the resist film changes to have the characteristic of being soluble in a developer is called a positive type, and a resist material in which the exposed portion of the resist film changes to have the characteristic of being insoluble in a developer is called a negative type.

Recently, in the manufacture of semiconductor devices and liquid crystal display devices, the pattern miniaturization is progressing rapidly due to the advancement of lithography technology. As a technique for miniaturization, the wavelength (high energy) of the exposure light source is generally shortened. Specifically, ultraviolet rays represented by g-line and i-line were used in the past, but currently, mass production of semiconductor devices using KrF excimer laser light or ArF excimer laser light is being carried out. In addition, studies are being conducted on EUV (extreme ultraviolet), EB (electron beam), X-ray, etc., which have shorter wavelengths (higher energy) than these excimer laser lights.

Resist materials are required to have lithographic characteristics such as sensitivity to these exposure light sources and resolution to reproduce fine dimensional patterns.

As a resist material satisfying such requirements, a chemically amplified resist composition containing a substrate component whose solubility in a developer changes by the action of an acid and an acid generator component that generates acid by exposure has been conventionally used.

For example, when the developer is an alkaline developer (alkaline developing process), a positive chemically amplified resist composition is generally used that contains a resin component (base resin) whose solubility in an alkaline developer increases by the action of an acid, and an acid generator component. When a resist film formed using such a resist composition is selectively exposed at the time of forming a resist pattern, acid is generated from the acid generator component in the exposed portion, and the polarity of the base resin increases by the action of the acid, so that the exposed portion of the resist film becomes soluble in the alkaline developer. Therefore, by performing alkaline developing, a positive pattern is formed in which the unexposed portion of the resist film remains as a pattern.

On the other hand, when such a chemically amplified resist composition is applied to a solvent development process using a developer containing an organic solvent (organic developer), as the polarity of the base resin increases, the solubility in the organic developer relatively decreases, so that the unexposed portion of the resist film is dissolved and removed by the organic developer, and a negative resist pattern is formed in which the exposed portion of the resist film remains as a pattern. The solvent development process that forms a negative resist pattern in this way is sometimes referred to as a negative development process.

Up to now, as a base resin of a chemically amplified resist composition, for example, polyhydroxystyrene (PHS) having high transparency with respect to KrF excimer laser light (248 nm), a resin in which the hydroxyl group is protected with an acid-dissociable, dissolution-inhibiting group (PHS-based resin), or a resin in which the hydroxyl group in the carboxyl group of (meth)acrylic acid is protected with an acid-dissociable, dissolution-inhibiting group ((meth)acrylic-based resin) have been used (for example, see Patent Document 1).

As the above acid-dissociative dissolution-inhibiting groups, the so-called acetal groups, such as chain-shaped ether groups represented by 1-ethoxyethyl groups or cyclic ether groups represented by tetrahydropyranyl groups, tertiary alkyl groups represented by tert-butyl groups, and tertiary alkoxycarbonyl groups represented by tert-butoxycarbonyl groups, are mainly used.

In addition, as acid generator components used in chemically amplified resist compositions, a wide variety of ones have been proposed so far, and for example, onium salt-based acid generators such as iodonium salts and sulfonium salts, oxime sulfonate-based acid generators, diazomethane-based acid generators, nitrobenzyl sulfonate-based acid generators, iminosulfonate-based acid generators, and disulfone-based acid generators are known.

Recently, photofabrication has become the mainstream of precision microfabrication technology. Photofabrication refers to a processing technology for manufacturing various precision parts by applying the chemically amplified resist composition to the surface of a workpiece to form a resist film, forming a resist pattern of a predetermined shape on the resist film, and using this as a mask to perform electroforming, such as chemical etching, electrolytic etching, or electroplating.

In such photofabrication, depending on the purpose, etc., a thick resist film having a film thickness of, for example, 8 ㎛ or more is formed on the surface of the workpiece, and a resist pattern is formed, and etching, etc. are performed.

Japanese Patent Publication No. 4-211258

When attempting to form a thick resist film using a chemically amplified resist composition, the thicker the resist film becomes, the more difficult it becomes to apply the chemically amplified resist composition to a workpiece at a uniform thickness. In addition, there is a problem that the lithography characteristics (e.g., dimensional uniformity, etc.) of the resist pattern formed are likely to deteriorate.

In addition, when forming a resist pattern using a chemically amplified resist composition, as the resist film becomes thicker, it tends to become more difficult to maintain sensitivity during exposure. In contrast, for example, by using a chemically amplified resist composition in which an iodonium salt is selected as an acid generator component, improvement in sensitivity is attempted.

However, in the review by the present inventors, it was confirmed that when a chemically amplified resist composition containing an iodonium salt was used, a phenomenon occurred in which foaming occurred when a support on which a resist film was formed was baked at a high temperature (180° C. or higher) (for example, during a bake treatment (post-bake) performed after a developing treatment or a rinsing treatment). In such a resist composition that is prone to foaming, there is a problem in that, for example, the effect of removing residues is not sufficient during an ashing treatment for reworking.

The present invention has been made in consideration of the above circumstances, and has as its object the provision of a resist composition having excellent lithography characteristics, good applicability, and suppression of foaming from a resist pattern during high-temperature baking, particularly when forming a thick resist film in the formation of a resist pattern, and a method for forming a resist pattern using the same.

In order to solve the above problem, the present invention adopts the following configuration.

That is, the first aspect of the present invention is a resist composition which generates an acid upon exposure and whose solubility in a developer changes by the action of the acid, the resist composition comprising a polymer compound (A1) having a structural unit (a10) represented by the following general formula (a10-1) and a structural unit (a1) including an acid-decomposable group whose polarity increases by the action of an acid, and an acid generator (B1) represented by the following general formula (b1), and characterized in that the solid content concentration in the resist composition is 30 mass% or more.

[Chemical Formula 1]

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. Ya ^x1 is a single bond or a divalent linking group. Wa ^x1 is an aromatic hydrocarbon group having a valence of (n _ax1 + 1). n _ax1 is an integer of 1 to 3. R ²⁰¹¹ , R ²⁰²¹ , and R ²⁰³¹ each independently represent an aryl group which may have a substituent. Two or more of R ²⁰¹¹ , R ²⁰²¹ , and R ²⁰³¹ may be bonded to each other to form a ring together with the sulfur atom in the formula. X ^- represents a counter anion.]

A second aspect of the present invention is a method for forming a resist pattern, characterized by having the steps of (i) forming a resist film on a support using a resist composition related to the first aspect, (ii) exposing the resist film, and (iii) developing the resist film after the exposure to form a resist pattern.

According to the present invention, in the formation of a resist pattern, particularly when forming a thick resist film, it is possible to provide a resist composition having excellent lithography characteristics, good applicability, and suppressing foaming from the resist pattern during high-temperature baking, and a method for forming a resist pattern using the same.

The resist composition and resist pattern forming method of the present invention are particularly useful for forming a resist pattern of a thick film.

In the scope of this specification and the claims of this patent, “aliphatic” is defined as a relative concept to aromatic, and means a group, compound, etc. that does not have aromaticity.

"Alkyl group", unless otherwise specified, includes a linear, branched, or cyclic monovalent saturated hydrocarbon group. The same applies to alkyl groups among alkoxy groups.

“Alkylene group”, unless otherwise specified, includes linear, branched, and cyclic divalent saturated hydrocarbon groups.

A “halogenated alkyl group” is a group in which some or all of the hydrogen atoms of an alkyl group are replaced with halogen atoms, and examples of the halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

A “fluorinated alkyl group” or “fluorinated alkylene group” refers to a group in which some or all of the hydrogen atoms of an alkyl group or alkylene group are replaced with fluorine atoms.

“Component unit” refers to a monomer unit (monomer unit) that constitutes a high molecular weight compound (resin, polymer, copolymer).

When it is described as “may have a substituent,” it includes both the case where a hydrogen atom (-H) is replaced with a monovalent group and the case where a methylene group (-CH ₂ -) is replaced with a divalent group.

“Exposure” is a concept that includes all exposure to radiation.

“(Meth)acrylic acid ester” refers to one or both of an acrylic acid ester having a hydrogen atom bonded to the α position and a methacrylic acid ester having a methyl group bonded to the α position.

“(Meth)acrylate” refers to one or both of acrylate having a hydrogen atom bonded to the α position and methacrylate having a methyl group bonded to the α position.

“(Meth)acrylic acid” refers to one or both of acrylic acid with a hydrogen atom bonded to the α position and methacrylic acid with a methyl group bonded to the α position.

“Structure unit derived from acrylic acid ester” refers to a structure unit formed by cleavage of the ethylenic double bond of acrylic acid ester.

“Acrylic acid ester” is a compound in which the hydrogen atom at the carboxyl group terminal of acrylic acid (CH ₂ = CH-COOH) is replaced with an organic group.

In the acrylic acid ester, the hydrogen atom bonded to the carbon atom at the α-position may be replaced by a substituent. The substituent (R ^α0 ) replacing the hydrogen atom bonded to the carbon atom at the α-position is an atom or group other than a hydrogen atom, and examples thereof include an alkyl group having 1 to 5 carbon atoms, a halogenated alkyl group having 1 to 5 carbon atoms, etc. Furthermore, it is also intended to include an itaconic acid diester in which the substituent (R ^α0 ) is substituted by a substituent containing an ester bond, or an α hydroxyacrylate ester in which the substituent (R ^α0 ) is substituted by a hydroxyalkyl group or a group modifying the hydroxyl group. In addition, the carbon atom at the α-position of the acrylic acid ester refers to the carbon atom to which the carbonyl group of acrylic acid is bonded, unless otherwise specified.

Hereinafter, an acrylic acid ester in which the hydrogen atom bonded to the carbon atom at the α position is substituted with a substituent is sometimes called an α-substituted acrylic acid ester. In addition, an acrylic acid ester and an α-substituted acrylic acid ester are sometimes collectively called an "(α-substituted) acrylic acid ester."

“Structure unit derived from acrylamide” refers to a structure unit formed by cleavage of the ethylenic double bond of acrylamide.

Acrylamide may have the hydrogen atom bonded to the carbon atom at the α position replaced by a substituent, or one or both of the hydrogen atoms of the amino group of acrylamide may be replaced by a substituent. In addition, the carbon atom at the α position of acrylamide refers to the carbon atom to which the carbonyl group of acrylamide is bonded, unless otherwise specified.

As a substituent substituting the hydrogen atom bonded to the carbon atom at the α position of acrylamide, examples thereof include the same ones as those exemplified as the substituent at the α position in the above α-substituted acrylic acid ester (substituent (R ^α0 )).

“A structural unit derived from hydroxystyrene” means a structural unit formed by the cleavage of the ethylenic double bond of hydroxystyrene. “A structural unit derived from a hydroxystyrene derivative” means a structural unit formed by the cleavage of the ethylenic double bond of a hydroxystyrene derivative.

The term "hydroxystyrene derivative" refers to a concept that includes those in which the hydrogen atom at the α-position of hydroxystyrene is replaced by another substituent such as an alkyl group or a halogenated alkyl group, and their derivatives. As their derivatives, examples thereof include those in which the hydrogen atom of a hydroxyl group of hydroxystyrene, which may be substituted by a substituent at the α-position, is replaced by an organic group; those in which a substituent other than a hydroxyl group is bonded to the benzene ring of hydroxystyrene, which may be substituted by a substituent at the α-position, etc. In addition, the α-position (carbon atom at the α-position) refers to a carbon atom to which a benzene ring is bonded, unless otherwise specified.

As a substituent substituting the hydrogen atom at the α position of hydroxystyrene, the same ones as those exemplified as the substituent at the α position in the above-mentioned α-substituted acrylic acid ester can be exemplified.

“A structural unit derived from vinylbenzoic acid or a vinylbenzoic acid derivative” refers to a structural unit formed by cleavage of the ethylenic double bond of vinylbenzoic acid or a vinylbenzoic acid derivative.

The term "vinylbenzoic acid derivative" is a concept that includes vinylbenzoic acid in which the hydrogen atom at the α-position is replaced by another substituent such as an alkyl group or a halogenated alkyl group, and derivatives thereof. Derivatives thereof include vinylbenzoic acid in which the hydrogen atom of the carboxyl group of vinylbenzoic acid, which may be substituted by a substituent at the α-position, is replaced by an organic group; vinylbenzoic acid in which the hydrogen atom at the α-position is replaced by a substituent, and a substituent other than a hydroxyl group and a carboxyl group is bonded to the benzene ring of vinylbenzoic acid, which may be substituted by a substituent at the α-position, etc. In addition, the α-position (carbon atom at the α-position) refers to the carbon atom to which the benzene ring is bonded, unless otherwise specified.

The term "styrene" includes styrene and styrene in which the hydrogen atom at the α position is substituted with another substituent such as an alkyl group or a halogenated alkyl group.

The term "styrene derivative" is a concept that includes styrene in which the hydrogen atom at the α-position is replaced by another substituent such as an alkyl group or a halogenated alkyl group, and their derivatives. As their derivatives, examples thereof include those in which the hydrogen atom at the α-position is substituted by a substituent and a substituent is bonded to the benzene ring of hydroxystyrene. In addition, unless otherwise specified, the α-position (carbon atom at the α-position) refers to the carbon atom to which the benzene ring is bonded.

“Structure unit derived from styrene” and “structural unit derived from a styrene derivative” mean a structure unit formed by cleavage of the ethylenic double bond of styrene or a styrene derivative.

The alkyl group as a substituent at the above α position is preferably a linear or branched alkyl group, and specifically, examples thereof include alkyl groups having 1 to 5 carbon atoms (methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group), etc.

In addition, the halogenated alkyl group as a substituent at the α position specifically includes a group in which some or all of the hydrogen atoms of the above "alkyl group as a substituent at the α position" are replaced with halogen atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like, and a fluorine atom is particularly preferable.

In addition, the hydroxyalkyl group as a substituent at the α position specifically includes a group in which some or all of the hydrogen atoms of the above "alkyl group as a substituent at the α position" are replaced with hydroxyl groups. The number of hydroxyl groups in the hydroxyalkyl group is preferably 1 to 5, and 1 is most preferable.

In the scope of this specification and the claims of this patent, depending on the structure represented by the chemical formula, there are cases where an aliphatic carbon exists and enantiomers or diastereo isomers can exist. In such cases, these isomers are represented by a single chemical formula. These isomers may be used alone or as a mixture.

(Resist composition)

The first aspect of the present invention is a resist composition that generates an acid upon exposure and whose solubility in a developer changes by the action of the acid.

One embodiment of such a resist composition includes a resist composition containing a base component (A) (hereinafter also referred to as “component (A)”) whose solubility in a developer changes by the action of an acid, an acid generator component (B) (hereinafter also referred to as “component (B)”) which generates acid by exposure, and an organic solvent component (S) (hereinafter also referred to as “component (S)”). In the resist composition of the present embodiment, component (A) includes a specific polymer compound (A1), component (B) includes a specific acid generator (B1), and the solid content concentration in the resist composition is 30 mass% or more.

The resist composition of the present embodiment is suitable for forming a resist pattern by exposure using a KrF excimer laser.

In addition, the resist composition of the present embodiment is suitable for forming a resist film of, for example, 1 to 10 μm thick on a support, and is particularly suitable for forming a resist pattern by depositing a thick resist film. The thick film referred to here means a film having a thickness of 6 μm or more. The resist composition of the present embodiment is preferably suitable for forming a resist film having a thickness of 6 μm or more, and even within this range, a thickness of 7 μm or more, and further a thickness of 8 μm or more.

When a resist film is formed using the resist composition of the present embodiment and selective exposure is performed on the resist film, acid is generated from component (B) in the exposed portion of the resist film, and the solubility of component (A) in the developing solution changes due to the action of the acid, whereas in the unexposed portion of the resist film, the solubility of component (A) in the developing solution does not change, so a difference in solubility in the developing solution occurs between the exposed portion and the unexposed portion of the resist film. Therefore, when the resist film is developed, if the resist composition is positive, the exposed portion of the resist film is dissolved and removed, and a positive resist pattern is formed, and if the resist composition is negative, the unexposed portion of the resist film is dissolved and removed, and a negative resist pattern is formed.

In this specification, a resist composition in which an exposed portion of a resist film is dissolved and removed to form a positive resist pattern is referred to as a positive resist composition, and a resist composition in which an unexposed portion of a resist film is dissolved and removed to form a negative resist pattern is referred to as a negative resist composition.

The resist composition of the present embodiment may be a positive resist composition or a negative resist composition.

In addition, the resist composition of the present embodiment may be used for an alkaline developing process that uses an alkaline developer for the developing process when forming a resist pattern, or may be used for a solvent developing process that uses a developer containing an organic solvent (organic developer) for the developing process.

The resist composition of the present embodiment has an acid-generating ability that generates acid upon exposure, and in addition to component (B), component (A) may be one that generates acid upon exposure.

(A) If the component generates an acid upon exposure, this (A) component becomes a "base component which generates an acid upon exposure and furthermore, the solubility in a developer changes by the action of the acid." If the (A) component is a base component which generates an acid upon exposure and furthermore, the solubility in a developer changes by the action of the acid, it is preferable that the (A1) component described below is a polymer compound which generates an acid upon exposure and furthermore, the solubility in a developer changes by the action of the acid. Examples of such polymer compounds include resins having a structural unit which generates an acid upon exposure. Known monomers can be used as monomers which induce a structural unit which generates an acid upon exposure.

＜(A) Component＞

(A) Component is a base component whose solubility in a developer changes due to the action of an acid.

In the present invention, the “base component” is an organic compound having film-forming ability, and preferably, an organic compound having a molecular weight of 500 or more is used. When the molecular weight of the organic compound is 500 or more, the film-forming ability is improved, and furthermore, it becomes easy to form a nano-level resist pattern.

Organic compounds used as base components are broadly classified into non-polymers and polymers.

As for non-polymers, those having a molecular weight of 500 or more and less than 4000 are usually used. Hereinafter, when referred to as “low-molecular-weight compound,” it refers to a non-polymer having a molecular weight of 500 or more and less than 4000.

As a polymer, one having a molecular weight of 1000 or more is usually used. Hereinafter, when referring to “resin,” “polymer compound,” or “polymer,” a polymer having a molecular weight of 1000 or more is indicated.

As for the molecular weight of the polymer, the weight average molecular weight converted to polystyrene by GPC (gel permeation chromatography) is used.

As the component (A) used in the resist composition of the present embodiment, at least the component (A1) is used, and other high molecular weight compounds and/or low molecular weight compounds may be used together with the component (A1).

In the resist composition of the present embodiment, component (A) includes a specific polymer compound (A1), that is, a polymer compound (A1) having a structural unit (a10) represented by the general formula (a10-1) described below and a structural unit (a1) including an acid-decomposable group whose polarity increases by the action of an acid (hereinafter also referred to as “component (A1)”).

When a resist film formed using a resist composition containing such a (A1) component is exposed, the structural unit (a1) has at least a part of its structure bonds cleaved by the action of an acid, thereby increasing its polarity. Therefore, the resist composition of the present embodiment becomes negative when the developer is an organic developer (solvent developing process), and becomes positive when the developer is an alkaline developer (alkaline developing process). Since the polarity of the (A1) component changes before and after exposure, by using the (A1) component, good developing contrast can be obtained not only in the alkaline developing process but also in the solvent developing process.

In short, when an alkaline developing process is applied, the (A1) component is hardly soluble in an alkaline developing solution before exposure, and when, for example, an acid is generated from the (B) component by exposure, the polarity increases due to the action of the acid, thereby increasing the solubility in an alkaline developing solution. Therefore, when the resist composition is applied onto a support to form a resist pattern, selective exposure is performed on the resist film obtained by selectively exposing the resist film, and the exposed portion of the resist film changes from hardly soluble to soluble in an alkaline developing solution, while the unexposed portion of the resist film does not change and remains hardly soluble in an alkaline developing solution, so that a positive resist pattern is formed by performing the alkaline developing solution.

Meanwhile, when a solvent development process is applied, the (A1) component has high solubility in an organic developer before exposure, and when an acid is generated from the (B) component by exposure, the polarity increases due to the action of the acid, and the solubility in the organic developer decreases. Therefore, when the resist composition is applied onto a support to form a resist pattern and the obtained resist film is selectively exposed, the exposed portion of the resist film changes from being soluble to being insoluble in the organic developer, while the unexposed portion of the resist film remains soluble and does not change, so by developing with an organic developer, contrast can be imparted between the exposed portion and the unexposed portion, and a negative resist pattern is formed.

· (A1) About the ingredients

(A1) The component is a polymer compound having a structural unit (a10) represented by the general formula (a10-1) and a structural unit (a1) including an acid-decomposable group whose polarity increases by the action of an acid.

≪Composition Unit (a10)≫

The constituent unit (a10) is a constituent unit represented by the following general formula (a10-1).

[Chemical formula 2]

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. Ya ^x1 is a single bond or a divalent linking group. Wa ^x1 is an aromatic hydrocarbon group having a valence of (n _ax1 + 1). n _ax1 is an integer of 1 to 3.]

In the above formula (a10-1), R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms.

The alkyl group having 1 to 5 carbon atoms of R is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and the like. The halogenated alkyl group having 1 to 5 carbon atoms of R is a group in which some or all of the hydrogen atoms of the alkyl group having 1 to 5 carbon atoms are replaced with halogen atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like, and a fluorine atom is particularly preferable.

As R, a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms is preferable, and from the perspective of ease of industrial availability, a hydrogen atom or a methyl group is most preferable.

In the above formula (a10-1), Ya ^x1 is a single bond or a divalent linking group.

As the divalent linking group in Ya ^x1 , for example, a divalent hydrocarbon group which may have a substituent and a divalent linking group containing a hetero atom are preferable.

· Divalent hydrocarbon group which may have a substituent:

If Ya ^x1 is a divalent hydrocarbon group that may have a substituent, the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group.

·· Aliphatic hydrocarbon group in Ya ^x1

The aliphatic hydrocarbon group refers to a hydrocarbon group that does not have aromaticity. The aliphatic hydrocarbon group may be saturated or unsaturated, and saturated is usually preferred.

The above aliphatic hydrocarbon group may include a straight-chain or branched-chain aliphatic hydrocarbon group, or an aliphatic hydrocarbon group containing a ring in its structure.

··· A straight or branched chain aliphatic hydrocarbon group

The linear aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.

As the linear aliphatic hydrocarbon group, a linear alkylene group is preferable, and specific examples thereof include a methylene group [-CH ₂ -], an ethylene group [-(CH ₂ ) ₂ -], a trimethylene group [-(CH ₂ ) ₃ -], a tetramethylene group [-(CH ₂ ) ₄ -], a pentamethylene group [-(CH ₂ ) ₅ -], and the like.

The branched chain aliphatic hydrocarbon group preferably has 3 to 10 carbon atoms, more preferably 3 to 6 carbon atoms, still more preferably 3 or 4 carbon atoms, and most preferably 3 carbon atoms.

As the branched-chain aliphatic hydrocarbon group, a branched-chain alkylene group is preferable, and specifically, alkylmethylene groups such as -CH(CH ₃ )-, -CH(CH ₂ CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CH ₃ )(CH ₂ CH ₃ )-, -C(CH ₃ )(CH ₂ CH ₂ CH ₃ )-, -C(CH ₂ CH ₃ ) ₂ -; alkylethylene groups such as -CH(CH ₃ )CH ₂ -, -CH(CH ₃ )CH(CH ₃ )-, -C(CH ₃ ) ₂ CH ₂ -, -CH(CH ₂ CH ₃ )CH ₂ -, -C(CH ₂ CH ₃ ) ₂ -CH ₂ -; Examples thereof include alkyltrimethylene groups such as -CH(CH ₃ )CH ₂ CH ₂ -, -CH ₂ CH(CH ₃ )CH ₂ -, and the like; alkylalkylene groups such as alkyltetramethylene groups such as -CH(CH ₃ )CH ₂ CH ₂ CH ₂ -, -CH ₂ CH(CH ₃ )CH ₂ CH ₂ -, and the like. As the alkyl group in the alkylalkylene group, a linear alkyl group having 1 to 5 carbon atoms is preferable.

The above linear or branched aliphatic hydrocarbon group may or may not have a substituent. Examples of the substituent include a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, a carbonyl group, etc.

··· Aliphatic hydrocarbon group containing a ring in the structure

Examples of the aliphatic hydrocarbon group containing a ring in the structure include a cyclic aliphatic hydrocarbon group that may include a substituent containing a hetero atom in the ring structure (a group in which two hydrogen atoms are removed from the aliphatic hydrocarbon ring), a group in which the cyclic aliphatic hydrocarbon group is bonded to the terminal of a linear or branched aliphatic hydrocarbon group, a group in which the cyclic aliphatic hydrocarbon group is interposed in the middle of a linear or branched aliphatic hydrocarbon group, and the like. Examples of the linear or branched aliphatic hydrocarbon group include the same ones as described above.

The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbon atoms, more preferably 3 to 12 carbon atoms.

The cyclic aliphatic hydrocarbon group may be a polycyclic group or a monocyclic group. As the monocyclic alicyclic hydrocarbon group, a group obtained by removing two hydrogen atoms from a monocycloalkane is preferable. As the monocycloalkane, a group having 3 to 6 carbon atoms is preferable, and specific examples thereof include cyclopentane and cyclohexane. As the polycyclic alicyclic hydrocarbon group, a group obtained by removing two hydrogen atoms from a polycycloalkane is preferable, and as the polycycloalkane, a group having 7 to 12 carbon atoms is preferable, and specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

The cyclic aliphatic hydrocarbon group may or may not have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, etc.

As the alkyl group as the above substituent, an alkyl group having 1 to 5 carbon atoms is preferable, and a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group is most preferable.

As the alkoxy group as the above substituent, an alkoxy group having 1 to 5 carbon atoms is preferable, a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, a tert-butoxy group are more preferable, and a methoxy group and an ethoxy group are most preferable.

As the halogen atom as the above substituent, examples thereof include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc., and a fluorine atom is preferred.

As the halogenated alkyl group as the above substituent, a group in which some or all of the hydrogen atoms of the alkyl group are replaced with the halogen atoms can be exemplified.

A cyclic aliphatic hydrocarbon group may have some of the carbon atoms constituting the ring structure replaced by a substituent containing a hetero atom. Preferred substituents containing the hetero atom are -O-, -C(=O)-O-, -S-, -S(=O) ₂ -, -S(=O) ₂ -O-.

·· Aromatic hydrocarbon group in Ya ^x1

The aromatic hydrocarbon group is a hydrocarbon group having at least one aromatic ring.

This aromatic ring is not particularly limited as long as it is a cyclic conjugated system having 4n + 2 π electrons, and may be a monocyclic ring or a polycyclic ring. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20, still more preferably 6 to 15, and particularly preferably 6 to 12. However, the carbon atoms in the substituent are not included in the carbon atoms in the substituent. Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and aromatic heterocycles in which some of the carbon atoms constituting the aromatic hydrocarbon ring are replaced with heteroatoms. Examples of the heteroatom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocycle include a pyridine ring, a thiophene ring, and the like.

As an aromatic hydrocarbon group, examples thereof include a group in which two hydrogen atoms are removed from the aromatic hydrocarbon ring or aromatic heterocycle (an arylene group or a heteroarylene group); a group in which two hydrogen atoms are removed from an aromatic compound (e.g., biphenyl, fluorene, etc.) containing two or more aromatic rings; a group in which one hydrogen atom of a group in which one hydrogen atom is removed from the aromatic hydrocarbon ring or aromatic heterocycle (an aryl group or a heteroaryl group) is replaced with an alkylene group (e.g., a group in which one hydrogen atom is additionally removed from the aryl group in an arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethyl group). The alkylene group bonded to the above aryl group or heteroaryl group preferably has 1 to 4 carbon atoms, more preferably 1 to 2 carbon atoms, and particularly preferably 1 carbon atoms.

The above aromatic hydrocarbon group may have a hydrogen atom substituted with a substituent. For example, a hydrogen atom bonded to an aromatic ring in the aromatic hydrocarbon group may be substituted with a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, and the like.

As the alkyl group as the above substituent, an alkyl group having 1 to 5 carbon atoms is preferable, and a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group is most preferable.

As the alkoxy group, halogen atom and halogenated alkyl group as the above substituent, examples thereof include those as substituents that substitute hydrogen atoms of the above cyclic aliphatic hydrocarbon group.

· Bivalent linking group containing heteroatoms:

When Ya ^x1 is a divalent linking group containing a hetero atom, preferable ones as the linking group are -O-, -C(=O)-O-, -C(=O)-, -OC(=O)-O-, -C(=O)-NH-, -NH-, -NH-C(=NH)- (H may be substituted with a substituent such as an alkyl group or an acyl group), -S-, -S(=O) ₂ -, -S(=O) ₂ -O-, general formula -Y ²¹ -OY ²² -, -Y ²¹ -O-, -Y ²¹ -C(=O)-O-, -C(=O)-OY ²¹ -, -[Y ²¹ -C(=O)-O] _m" -Y ²² -, -Y ²¹ -OC(=O)-Y ²² - or -Y ²¹ -S(=O) ₂ -OY Examples thereof include ^a group represented by [wherein Y ²¹ and Y ²² are each independently a divalent hydrocarbon group which may have a substituent, O is an oxygen atom, and m" is an integer from 0 to 3.]

When the divalent linking group containing the above hetero atom is -C(=O)-NH-, -C(=O)-NH-C(=O)-, -NH-, -NH-C(=NH)-, the H may be substituted with a substituent such as an alkyl group or an acyl group. The substituent (alkyl group, acyl group, etc.) preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably 1 to 5 carbon atoms.

In the general formulas -Y ²¹ -OY ²² -, -Y ²¹ -O-, -Y ²¹ -C(=O)-O-, -C(=O)-OY ²¹ -, -[Y ²¹ -C(=O)-O] _m" -Y ²² -, -Y ²¹ -OC(=O)-Y ²² - or -Y ²¹ -S(=O) ₂ -OY ²² -, Y ²¹ and Y ²² are each independently a divalent hydrocarbon group which may have a substituent. As the divalent hydrocarbon group, examples thereof include the same as (divalent hydrocarbon groups which may have a substituent) exemplified in the explanation of the divalent connecting group above.

As Y ²¹ , a linear aliphatic hydrocarbon group is preferable, a linear alkylene group is more preferable, a linear alkylene group having 1 to 5 carbon atoms is still more preferable, and a methylene group or an ethylene group is particularly preferable.

As Y ²² , a linear or branched aliphatic hydrocarbon group is preferable, and a methylene group, an ethylene group or an alkylmethylene group is more preferable. The alkyl group in the alkylmethylene group is preferably a linear alkyl group having 1 to 5 carbon atoms, more preferably a linear alkyl group having 1 to 3 carbon atoms, and most preferably a methyl group.

In the group represented by the formula -[Y ²¹ -C(=O)-O] _m" -Y ²² -, m" is an integer of 0 to 3, preferably an integer of 0 to 2, more preferably 0 or 1, and particularly preferably 1. In short, among the groups represented by the formula -[Y ²¹ -C(=O)-O] _m" -Y ²² -, a group represented by the formula -Y ²¹ -C(=O)-OY ²² - is particularly preferable. Among these, a group represented by the formula -(CH ₂ ) _a' -C(=O)-O-(CH ₂ ) _b ' - is preferable. In the formula, a' is an integer of 1 to 10, preferably an integer of 1 to 8, more preferably an integer of 1 to 5, still more preferably 1 or 2, and most preferably 1. b' is an integer of 1 to 10, preferably an integer of 1 to 8, more preferably an integer of 1 to 5, still more preferably 1 or 2, and most preferably 1.

As for Ya ^x1 , it is preferable that it is a single bond, an ester bond [-C(=O)-O-], an ether bond (-O-), -C(=O)-NH-, a linear or branched alkylene group, or a combination thereof, and among them, a single bond is particularly more preferable.

In the above formula (a10-1), Wa ^x1 is an aromatic hydrocarbon group of (n _ax1 + 1).

As an aromatic hydrocarbon group in Wa ^x1 , a group in which (n _ax1 + 1) hydrogen atoms are removed from the aromatic ring can be exemplified. The aromatic ring here is not particularly limited as long as it is a ring-shaped conjugated system having 4n + 2 π electrons, and may be a monocyclic ring or a polycyclic ring. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms. Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and aromatic heterocycles in which some of the carbon atoms constituting the aromatic hydrocarbon ring are replaced with heteroatoms. Examples of the heteroatom in the aromatic heterocycle include an oxygen atom, a sulfur atom, a nitrogen atom, and the like. As aromatic heterocyclic rings, specific examples include a pyridine ring and a thiophene ring.

In the above formula (a10-1), n _ax1 is an integer from 1 to 3, preferably 1 or 2, and more preferably 1.

Below, specific examples of the constituent units represented by the general formula (a10-1) are shown.

In the formula below, R ^α represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

[Chemical Formula 3]

(A1) The composition unit (a10) of the component may be one type or two or more types.

Among the above, the structural unit (a10) is preferably a structural unit including a hydroxystyrene skeleton, and a structural unit represented by the following general formula (a10-1-1) is particularly preferable.

[Chemical Formula 4]

[In the formula, R ^st represents a hydrogen atom or a methyl group. m ₀₁ represents an integer from 1 to 3.]

(A1) Among the components, the proportion of the structural unit (a10) is preferably 10 to 95 mol%, more preferably 30 to 90 mol%, and particularly preferably 50 to 85 mol%, with respect to the total (100 mol%) of all structural units constituting the (A1) component.

By setting the ratio of the constituent unit (a10) to the lower limit of the above-described preferable range or higher, the lithography characteristics such as the developing characteristics and the EL margin are further improved, and by setting it to the upper limit of the above-described preferable range or lower, it becomes easy to achieve a balance with the other constituent units.

≪Composition Unit (a1)≫

The constituent unit (a1) is a constituent unit including an acid-decomposable group whose polarity increases by the action of an acid.

An “acid-decomposable group” is a group having acid decomposability in which at least a portion of the bonds in the structure of the acid-decomposable group can be cleaved by the action of an acid.

As an acid-decomposable group whose polarity increases by the action of an acid, an example of such a group is a group that decomposes by the action of an acid to generate a polar group.

Polar groups include, for example, a carboxyl group, a hydroxyl group, an amino group, a sulfo group (-SO ₃ H), etc. Among these, a polar group containing -OH in its structure (hereinafter sometimes referred to as an "OH-containing polar group") is preferable, a carboxyl group or a hydroxyl group is more preferable, and a carboxyl group is particularly preferable.

More specifically, as an acid-dissociable group, a group in which the polar group is protected by an acid-dissociable group (for example, a group in which a hydrogen atom of an OH-containing polar group is protected by an acid-dissociable group) can be mentioned.

Here, the term “acid-dissociable group” refers to either (i) a group having acid dissociability, which can cause cleavage of a bond between the acid-dissociable group and an atom adjacent to the acid-dissociable group by the action of an acid, or (ii) a group which can cause cleavage of a bond between the acid-dissociable group and an atom adjacent to the acid-dissociable group by a further decarboxylation reaction after some of the bonds have been cleaved by the action of an acid.

The acid-dissociable group constituting the acid-decomposable group must have a lower polarity than the polar group generated by the dissociation of the acid-dissociable group, and thus, when the acid-dissociable group is dissociated by the action of an acid, a polar group having a higher polarity than the acid-dissociable group is generated, thereby increasing the polarity. As a result, the polarity of the entire (A1) component increases. As the polarity increases, the solubility in the developer relatively changes, and when the developer is an alkaline developer, the solubility increases, and when the developer is an organic developer, the solubility decreases.

As for acid dissociation groups, those proposed so far as acid dissociation groups of base resins for chemically amplified resists can be mentioned.

As acid-dissociable groups for base resins for chemically amplified resists, specific examples thereof include the “acetal-type acid-dissociable group,” the “tertiary alkyl ester-type acid-dissociable group,” and the “tertiary alkyloxycarbonyl acid-dissociable group,” which are described below.

· Acetal type acid dissociation group:

As an acid-labile group protecting a carboxyl group or a hydroxyl group among the above polar groups, an acid-labile group represented by the following general formula (a1-r-1) (hereinafter sometimes referred to as an “acetal-type acid-labile group”) can be mentioned, for example.

[Chemical Formula 5]

[In the formula, Ra' ¹ and Ra' ² are hydrogen atoms or alkyl groups. Ra' ³ is a hydrocarbon group, and Ra' ³ may form a ring by combining with either Ra' ¹ or Ra' ^2. ]

In the formula (a1-r-1), it is preferable that at least one of Ra' ¹ and Ra' ² is a hydrogen atom, and it is more preferable that both are hydrogen atoms.

When Ra' ¹ or Ra' ² is an alkyl group, examples of the alkyl group include the same alkyl groups as those exemplified as substituents which may be bonded to the carbon atom at the α position in the description of the above-mentioned α-substituted acrylic acid ester, and an alkyl group having 1 to 5 carbon atoms is preferable. Specifically, a linear or branched alkyl group is preferable. More specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and the like can be mentioned, and a methyl group or an ethyl group is more preferable, and a methyl group is particularly preferable.

Among the formulas (a1-r-1), the hydrocarbon group of Ra' ³ may include a linear or branched alkyl group or a cyclic hydrocarbon group.

The linear alkyl group preferably has 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms. Specifically, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, and the like can be mentioned. Among these, a methyl group, an ethyl group, or an n-butyl group is preferable, and a methyl group or an ethyl group is more preferable.

The branched chain alkyl group preferably has 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms. Specifically, examples thereof include an isopropyl group, an isobutyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a 1,1-diethylpropyl group, a 2,2-dimethylbutyl group, and the like, with an isopropyl group being preferred.

When Ra' ³ is a cyclic hydrocarbon group, the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and may also be a polycyclic group or a monocyclic group.

As the aliphatic hydrocarbon group which is a monocyclic group, a group in which one hydrogen atom is removed from a monocycloalkane is preferable. As the monocycloalkane, a group having 3 to 6 carbon atoms is preferable, and specific examples thereof include cyclopentane and cyclohexane.

As the aliphatic hydrocarbon group which is a polycyclic group, a group having one hydrogen atom removed from a polycycloalkane is preferable, and as the polycycloalkane, a group having 7 to 12 carbon atoms is preferable, and specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

When the cyclic hydrocarbon group of Ra' ³ becomes an aromatic hydrocarbon group, the aromatic hydrocarbon group is a hydrocarbon group having at least one aromatic ring.

This aromatic ring is not particularly limited as long as it is a cyclic conjugated system having 4n + 2 π electrons, and may be a monocyclic ring or a polycyclic ring. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms. Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and aromatic heterocycles in which some of the carbon atoms constituting the aromatic hydrocarbon ring are replaced with heteroatoms. Examples of the heteroatom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocycle include a pyridine ring, a thiophene ring, and the like.

Specific examples of the aromatic hydrocarbon group in Ra' ³ include a group in which one hydrogen atom is removed from the aromatic hydrocarbon ring or aromatic heterocycle (an aryl group or a heteroaryl group); a group in which one hydrogen atom is removed from an aromatic compound (e.g., biphenyl, fluorene, etc.) containing two or more aromatic rings; a group in which one hydrogen atom of the aromatic hydrocarbon ring or aromatic heterocycle is replaced by an alkylene group (e.g., an arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, a 2-naphthylethyl group, etc.). The alkylene group bonded to the aromatic hydrocarbon ring or aromatic heterocycle preferably has 1 to 4 carbon atoms, more preferably 1 to 2 carbon atoms, and particularly preferably 1 carbon atoms.

When Ra' ³ forms a ring by combining with either Ra' ¹ or Ra' ² , the ring group is preferably a 4 to 7-membered ring, and more preferably a 4 to 6-membered ring. Specific examples of the ring group include a tetrahydropyranyl group, a tetrahydrofuranyl group, and the like.

· Third-class alkyl ester type acid-dissociating group:

Among the above polar groups, an acid-labile group protecting a carboxyl group may be, for example, an acid-labile group represented by the following general formula (a1-r-2).

In addition, among the acid-dissociable groups represented by the following formula (a1-r-2), those composed of alkyl groups are sometimes referred to as “tertiary alkyl ester type acid-dissociable groups” for convenience.

[Chemical formula 6]

[In the formula, Ra' ⁴ to Ra' ⁶ are each a hydrocarbon group, and Ra' ⁵ and Ra' ⁶ may be combined with each other to form a ring.]

As hydrocarbon groups of Ra' ⁴ to Ra' ⁶ , those identical to those of Ra' ³ can be mentioned.

It is preferable that Ra' ⁴ is an alkyl group having 1 to 5 carbon atoms. When Ra' ⁵ and Ra' ⁶ are bonded to each other to form a ring, a group represented by the following general formula (a1-r2-1) can be exemplified. On the other hand, when Ra' ⁴ to Ra' ⁶ are not bonded to each other and are independent hydrocarbon groups, a group represented by the following general formula (a1-r2-2) can be exemplified.

[Chemical formula 7]

[In the formula, Ra' ¹⁰ is an alkyl group having 1 to 10 carbon atoms. Ra' ¹¹ is a group that forms an aliphatic ring group together with the carbon atom to which Ra' ¹⁰ is bonded. Ra' ¹² to Ra' ¹⁴ each independently represent a hydrocarbon group.]

In formula (a1-r2-1), the alkyl group having 1 to 10 carbon atoms of Ra' ¹⁰ is preferably a group exemplified as a linear or branched alkyl group of Ra' ³ in formula (a1-r-1). In formula (a1-r2-1), the aliphatic cyclic group formed by Ra' ¹¹ together with the carbon atom to which Ra' ¹⁰ is bonded is preferably a group exemplified as an aliphatic hydrocarbon group which is a monocyclic group or polycyclic group of Ra' ³ in formula (a1-r-1).

In formula (a1-r2-2), it is preferable that Ra' ¹² and Ra' ¹⁴ are each independently an alkyl group having 1 to 10 carbon atoms, and the alkyl group is more preferably a group exemplified as a linear or branched alkyl group of Ra' ³ in formula (a1-r-1), a linear alkyl group having 1 to 5 carbon atoms is further preferable, and a methyl group or an ethyl group is particularly preferable.

In the formula (a1-r2-2), Ra' ¹³ is preferably an aliphatic hydrocarbon group, which is a linear or branched alkyl group, a monocyclic group or a polycyclic group, exemplified as a hydrocarbon group of Ra' ³ in the formula (a1-r-1). Among these, it is more preferable that Ra' ¹³ is a linear or branched alkyl group exemplified as a hydrocarbon group of Ra' ³ .

Below, specific examples of groups represented by the above formula (a1-r2-1) are given. * represents a bond (the same applies hereinafter in the present specification).

[Chemical formula 8]

[Chemical formula 9]

Specific examples of groups represented by the above formula (a1-r2-2) are given below.

[Chemical Formula 10]

· Tertiary alkyloxycarbonyl acid dissociation group:

As an acid-labile group protecting a hydroxyl group among the above polar groups, an acid-labile group represented by the following general formula (a1-r-3) (hereinafter, for convenience, sometimes referred to as a “tertiary alkyloxycarbonyl acid-labile group”) can be mentioned.

[Chemical Formula 11]

[In the formula, Ra' ⁷ to Ra' ⁹ are each an alkyl group.]

In formula (a1-r-3), Ra' ⁷ to Ra' ⁹ are each preferably an alkyl group having 1 to 5 carbon atoms, more preferably 1 to 3.

Additionally, the total number of carbon atoms in each alkyl group is preferably 3 to 7, more preferably 3 to 5, and most preferably 3 to 4.

Among the above, as the acid-dissociable group of the base resin for the chemically amplified resist, a tertiary alkyl ester type acid-dissociable group is preferable because it is easy to obtain a combination effect with the (B) component (resolution, dimensional uniformity (CDU) within the support surface (Shot), etc.), an acid-dissociable group represented by the formula (a1-r-2) is more preferable, and a group represented by the general formula (a1-r2-2) is still more preferable.

Among the groups represented by the general formula (a1-r2-2), the group represented by the above formula (r-pr-c1), formula (r-pr-c2), or formula (r-pr-c3) is preferable.

As the structural unit (a1), examples thereof include a structural unit derived from an acrylic acid ester in which a hydrogen atom bonded to a carbon atom at the α-position may be substituted with a substituent, a structural unit derived from acrylamide, a structural unit derived from hydroxystyrene or a hydroxystyrene derivative in which at least a part of the hydrogen atoms in a hydroxyl group of the structural unit are protected by a substituent containing the acid-decomposable group, a structural unit derived from vinylbenzoic acid or a vinylbenzoic acid derivative in which at least a part of the hydrogen atoms in -C(=O)-OH of the structural unit are protected by a substituent containing the acid-decomposable group, and the like.

Among the above, as the structural unit (a1), a structural unit derived from an acrylic acid ester in which the hydrogen atom bonded to the carbon atom at the α position may be substituted with a substituent is preferable.

Preferred specific examples of such a constituent unit (a1) include a constituent unit represented by the following general formula (a1-1) or (a1-2).

[Chemical Formula 12]

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. Va ¹ is a divalent hydrocarbon group which may have an ether bond. n _a1 is an integer of 0 to 2. Ra ¹ is an acid-labile group represented by the above formula (a1-r-1) or (a1-r-2). Wa ¹ is a hydrocarbon group having a valence of n _a2 + 1. n _a2 is an integer of 1 to 3. Ra ² is an acid-labile group represented by the above formula (a1-r-1) or (a1-r-3).]

In the above formula (a1-1), the alkyl group having 1 to 5 carbon atoms of R is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specifically, examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and the like. The halogenated alkyl group having 1 to 5 carbon atoms is a group in which some or all of the hydrogen atoms of the alkyl group having 1 to 5 carbon atoms are replaced with halogen atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like, and a fluorine atom is particularly preferable.

As R, a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms is preferable, and from the perspective of ease of industrial availability, a hydrogen atom or a methyl group is most preferable.

In the above formula (a1-1), the divalent hydrocarbon group which may have an ether bond of Va ¹ is the same as the case in which Ya ^x1 in the above formula (a10-1) is a divalent hydrocarbon group which may have an ether bond as a substituent.

In the above formula (a1-2), the hydrocarbon group of n _a2 + 1 in Wa ¹ may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. The aliphatic hydrocarbon group means a hydrocarbon group that does not have aromaticity, and may be saturated or unsaturated, and is usually preferably saturated. Examples of the aliphatic hydrocarbon group include a linear or branched aliphatic hydrocarbon group, an aliphatic hydrocarbon group including a ring in its structure, or a group obtained by combining a linear or branched aliphatic hydrocarbon group and an aliphatic hydrocarbon group including a ring in its structure.

Among the above n _a2 + 1 groups, 2 to 4 are preferable, and 2 or 3 are more preferable.

Below, specific examples of the constituent units represented by the above formula (a1-1) are shown.

In each of the formulas below, R ^α represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

[Chemical Formula 13]

[Chemical Formula 14]

[Chemical Formula 15]

[Chemical Formula 16]

[Chemical Formula 17]

Below, specific examples of the constituent units represented by the above formula (a1-2) are shown.

[Chemical Formula 18]

(A1) The composition unit (a1) of the component may be one type or two or more types.

(A1) Among the components, the proportion of the structural unit (a1) is preferably 5 to 90 mol%, more preferably 10 to 70 mol%, and particularly preferably 15 to 50 mol%, with respect to the total (100 mol%) of all structural units constituting the (A1) component.

By setting the ratio of the constituent unit (a1) to the lower limit of the above-mentioned preferable range or higher, the contrast between the exposed and unexposed areas of the resist film becomes higher, and the resolution is improved. On the other hand, by setting it to the upper limit of the above-mentioned preferable range or lower, it becomes easy to achieve a balance with the other constituent units.

≪Other components≫

(A1) The component may have other constituent units other than the constituent unit (a10) and constituent unit (a1) described above.

Other structural units include, for example, a structural unit (a2) including a lactone-containing cyclic group, a -SO ₂ - containing cyclic group or a carbonate-containing cyclic group (except for those corresponding to structural unit (a10) or structural unit (a1)), a structural unit (a4) including an acid-non-dissociable aliphatic cyclic group, a structural unit derived from styrene, a structural unit derived from a styrene derivative (except for those corresponding to structural unit (a10)), a structural unit including a polar group-containing aliphatic hydrocarbon group (except for all of the structural units described above), etc.

· Composition unit (a2)

The structural unit (a2) is a structural unit comprising a lactone-containing cyclic group, a -SO ₂ - containing cyclic group or a carbonate-containing cyclic group (except for those corresponding to structural unit (a10) or structural unit (a1)).

The lactone-containing cyclic group, -SO ₂ --containing cyclic group or carbonate-containing cyclic group of the structural unit (a2) is effective in increasing the adhesion of the resist film to the substrate when the (A1) component is used for forming the resist film. In addition, since the (A1) component has the structural unit (a2), in an alkaline developing process, the solubility of the resist film in an alkaline developing solution is increased during development.

"Lactone-containing cyclic group" refers to a cyclic group containing a ring (lactone ring) containing -O-C(=O)- in its ring skeleton. The lactone ring is counted as the first ring, and if it is only a lactone ring, it is called a monocyclic group, and if it additionally has another ring structure, it is called a polycyclic group regardless of the structure. The lactone-containing cyclic group may be a monocyclic group or a polycyclic group.

As for the lactone-containing cyclic group in the constituent unit (a2), any one can be used without particular limitation. Specifically, groups represented by the following general formulae (a2-r-1) to (a2-r-7) can be mentioned.

[Chemical Formula 19]

[In the formula, Ra' ²¹ is each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, -COOR", -OC(=O)R", a hydroxyalkyl group, or a cyano group. R" is a hydrogen atom, an alkyl group, a lactone-containing cyclic group, a carbonate-containing cyclic group, or a -SO ₂ - containing cyclic group. A" is an alkylene group having 1 to 5 carbon atoms which may include an oxygen atom (-O-) or a sulfur atom (-S-), an oxygen atom, or a sulfur atom. n' is an integer of 0 to 2, and m' is 0 or 1.]

Among the above general formulae (a2-r-1) to (a2-r-7), the alkyl group for Ra' ²¹ is preferably an alkyl group having 1 to 6 carbon atoms. The alkyl group is preferably linear or branched. Specifically, examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a hexyl group, and the like. Among these, a methyl group or an ethyl group is preferable, and a methyl group is particularly preferable.

As the alkoxy group in Ra' ²¹ , an alkoxy group having 1 to 6 carbon atoms is preferable. The alkoxy group is preferably linear or branched. Specifically, a group in which an alkyl group as exemplified as the alkyl group in Ra' ²¹ is linked to an oxygen atom (-O-) can be exemplified.

Halogen atoms in Ra' ²¹ include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc., and fluorine atoms are preferred.

As the halogenated alkyl group in Ra' ²¹ , a group in which some or all of the hydrogen atoms of the alkyl group in Ra' ²¹ are replaced with the halogen atoms can be exemplified. As the halogenated alkyl group, a fluorinated alkyl group is preferable, and a perfluoroalkyl group is particularly preferable.

In -COOR", -OC(=O)R" in Ra' ²¹ , R" is all a hydrogen atom, an alkyl group, a lactone-containing cyclic group, a carbonate-containing cyclic group, or a -SO ₂ - containing cyclic group.

The alkyl group in "R" may be linear, branched or cyclic, and the number of carbon atoms is preferably 1 to 15.

When "R" is a straight-chain or branched-chain alkyl group, it is preferably one having 1 to 10 carbon atoms, more preferably one having 1 to 5 carbon atoms, and particularly preferably a methyl group or an ethyl group.

When "R" is a cyclic alkyl group, it is preferably one having 3 to 15 carbon atoms, more preferably one having 4 to 12 carbon atoms, and most preferably one having 5 to 10 carbon atoms. Specifically, examples thereof include a group having one or more hydrogen atoms removed from a monocycloalkane, which may or may not be substituted with a fluorine atom or a fluorinated alkyl group; a group having one or more hydrogen atoms removed from a polycycloalkane such as a bicycloalkane, a tricycloalkane, or a tetracycloalkane; and more specifically, a group having one or more hydrogen atoms removed from a monocycloalkane such as cyclopentane or cyclohexane; a group having one or more hydrogen atoms removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane.

As the lactone-containing cyclic group in "R", the same groups as those represented by the general formulae (a2-r-1) to (a2-r-7) can be exemplified.

As the carbonate-containing cyclic group in "R", the carbonate-containing cyclic group is the same as the carbonate-containing cyclic group described below, and specifically, groups represented by the general formulas (ax3-r-1) to (ax3-r-3) can be exemplified.

As the -SO ₂ -containing cyclic group in "R", the -SO ₂ -containing cyclic group is the same as that described later, and specifically, groups represented by the general formulae (a5-r-1) to (a5-r-4) can be mentioned.

As the hydroxyalkyl group in Ra' ²¹ , a group having 1 to 6 carbon atoms is preferable, and specifically, a group in which at least one hydrogen atom of the alkyl group in Ra' ²¹ is replaced with a hydroxyl group can be mentioned.

Among the above general formulas (a2-r-2), (a2-r-3), and (a2-r-5), the alkylene group having 1 to 5 carbon atoms in A" is preferably a linear or branched alkylene group, and examples thereof include a methylene group, an ethylene group, an n-propylene group, and an isopropylene group. When the alkylene group contains an oxygen atom or a sulfur atom, specific examples thereof include a group in which -O- or -S- is present at the terminal or between the carbon atoms of the alkylene group, and examples thereof include -O-CH ₂ -, -CH ₂ -O-CH ₂ -, -S-CH ₂ -, -CH ₂ -S-CH ₂ -, and the like. As A", an alkylene group having 1 to 5 carbon atoms or -O- is preferable, an alkylene group having 1 to 5 carbon atoms is more preferable, and a methylene group is most preferable.

Below, specific examples of groups represented by general formulas (a2-r-1) to (a2-r-7) are given.

[Chemical formula 20]

[Chemical Formula 21]

A "-SO ₂ -containing cyclic group" refers to a cyclic group containing a ring containing -SO ₂ - in its ring skeleton, and specifically, it is a cyclic group in which the sulfur atom (S) in -SO ₂ - forms a part of the ring skeleton of the cyclic group. The ring containing -SO ₂ - in the ring skeleton is counted as the first ring, and if it is the only ring, it is called a monocyclic group, and if it further has another ring structure, it is called a polycyclic group regardless of the structure. The -SO ₂ -containing cyclic group may be a monocyclic group or a polycyclic group.

- The -SO ₂ - containing cyclic group is preferably a cyclic group containing -O-SO ₂ - in its ring skeleton, that is, a cyclic group containing a sultone ring in which -OS- of -O-SO ₂ - forms a part of the ring skeleton.

-SO ₂ - As a cyclic group containing cyclic groups, more specifically, groups represented by the following general formulae (a5-r-1) to (a5-r-4) can be mentioned.

[Chemical Formula 22]

[In the formula, Ra' ⁵¹ is each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, -COOR", -OC(=O)R", a hydroxyalkyl group, or a cyano group. R" is a hydrogen atom, an alkyl group, a lactone-containing cyclic group, a carbonate-containing cyclic group, or a -SO ₂ - containing cyclic group. A" is an alkylene group having 1 to 5 carbon atoms which may include an oxygen atom or a sulfur atom, an oxygen atom, or a sulfur atom. n' is an integer of 0 to 2.]

Among the above general formulas (a5-r-1) to (a5-r-2), A" is identical to A" among the above general formulas (a2-r-2), (a2-r-3), and (a2-r-5).

As the alkyl group, alkoxy group, halogen atom, halogenated alkyl group, -COOR", -OC(=O)R", and hydroxyalkyl group in Ra' ⁵¹ , examples thereof include the same groups as those exemplified in the explanation for Ra' ²¹ in the general formulae (a2-r-1) to (a2-r-7).

Below are specific examples of groups represented by the general formulas (a5-r-1) to (a5-r-4). "Ac" in the formulas represents an acetyl group.

[Chemical Formula 23]

[Chemical Formula 24]

[Chemical Formula 25]

"Carbonate-containing cyclic group" refers to a cyclic group containing a ring (carbonate ring) containing -O-C(=O)-O- in its ring skeleton. The carbonate ring is counted as the first ring, and if it is only a carbonate ring, it is called a monocyclic group, and if it additionally has another ring structure, it is called a polycyclic group regardless of the structure. The carbonate-containing cyclic group may be a monocyclic group or a polycyclic group.

As the carbonate ring-containing cyclic group, any one can be used without particular limitation. Specifically, groups represented by the following general formulae (ax3-r-1) to (ax3-r-3) can be mentioned.

[Chemical Formula 26]

[In the formula, Ra' ^x31 is each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, -COOR", -OC(=O)R", a hydroxyalkyl group, or a cyano group. R" is a hydrogen atom, an alkyl group, a lactone-containing cyclic group, a carbonate-containing cyclic group, or a -SO ₂ - containing cyclic group. A" is an alkylene group having 1 to 5 carbon atoms which may include an oxygen atom or a sulfur atom, an oxygen atom, or a sulfur atom. p' is an integer of 0 to 3, and q' is 0 or 1.]

Among the above general formulas (ax3-r-2) to (ax3-r-3), A" is identical to A" among the above general formulas (a2-r-2), (a2-r-3), and (a2-r-5).

As the alkyl group, alkoxy group, halogen atom, halogenated alkyl group, -COOR", -OC(=O)R", and hydroxyalkyl group in Ra' ³¹ , examples thereof include the same groups as those exemplified in the explanation of Ra' ²¹ in the general formulae (a2-r-1) to (a2-r-7).

Below, specific examples of groups represented by the general formulas (ax3-r-1) to (ax3-r-3) are given.

[Chemical Formula 27]

As the structural unit (a2), among them, a structural unit derived from an acrylic acid ester in which the hydrogen atom bonded to the carbon atom at the α position may be substituted with a substituent is preferable.

It is preferable that these constituent units (a2) be constituent units represented by the following general formula (a2-1).

[Chemical formula 28]

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. Ya ²¹ is a single bond or a divalent linking group. La ²¹ is -O-, -COO-, -CON(R')-, -OCO-, -CONHCO-, or -CONHCS-, and R' represents a hydrogen atom or a methyl group. However, when La ²¹ is -O-, Ya ²¹ does not become -CO-. Ra ²¹ is a lactone-containing cyclic group, a carbonate-containing cyclic group, or a -SO ₂ --containing cyclic group.]

In the above formula (a2-1), R is the same as above.

As the divalent linking group of Ya ²¹ , examples thereof include the same divalent linking groups as those in Ya ^x1 in the general formula (a10-1) described above. Among these, Ya ²¹ is preferably a single bond, an ester bond [-C(=O)-O-], an ether bond (-O-), a linear or branched alkylene group, or a combination thereof.

In the above formula (a2-1), Ra ²¹ is a lactone-containing cyclic group, a -SO ₂ - containing cyclic group, or a carbonate-containing cyclic group.

As the lactone-containing cyclic group, -SO ₂ -- containing cyclic group, and carbonate-containing cyclic group in Ra ²¹ , groups respectively represented by the above-mentioned general formulae (a2-r-1) to (a2-r-7), groups respectively represented by the general formulae (a5-r-1) to (a5-r-4), and groups respectively represented by the general formulae (ax3-r-1) to (ax3-r-3) can be preferably exemplified.

Among them, a lactone-containing cyclic group or a -SO ₂ - containing cyclic group is preferable, and a group represented by the general formula (a2-r-1), (a2-r-2), (a2-r-6) or (a5-r-1) is more preferable. Specifically, any group represented by the chemical formulas (r-lc-1-1) to (r-lc-1-7), (r-lc-2-1) to (r-lc-2-18), (r-lc-6-1), (r-sl-1-1) and (r-sl-1-18) is more preferable.

(A1) The composition unit (a2) of the component may be one type or two or more types.

When the (A1) component has a structural unit (a2), the proportion of the structural unit (a2) among the (A1) component is preferably 1 to 40 mol%, more preferably 2 to 20 mol%, and still more preferably 5 to 10 mol%, with respect to the total (100 mol%) of all structural units constituting the (A1) component.

By setting the ratio of the constituent unit (a2) to the lower limit of the above-mentioned preferable range or higher, the effect of containing the constituent unit (a2) is sufficiently obtained. On the other hand, by setting it to the upper limit of the above-mentioned preferable range or lower, it becomes easy to achieve a balance with other constituent units, and various lithographic characteristics and pattern shapes become good.

· Composition unit (a4)

The constituent unit (a4) is a constituent unit containing a non-dissociable aliphatic cyclic group.

(A1) Since the component has the structural unit (a4), the dry etching resistance of the formed resist pattern is improved. In addition, the hydrophobicity of the (A) component is increased. The improvement in hydrophobicity contributes to the improvement of the resolution, resist pattern shape, etc., especially in the case of resist pattern formation by a solvent development process.

The “acid non-dissociable cyclic group” in the constituent unit (a4) is a cyclic group that remains in the constituent unit without dissociation when acid is generated in the resist composition by exposure (for example, when acid is generated from the (B) component described below).

As the structural unit (a4), for example, a structural unit derived from an acrylic acid ester containing an acid non-dissociable aliphatic cyclic group is preferable. As the aliphatic cyclic group, many of those known in the art can be used as resin components of resist compositions for ArF excimer lasers, KrF excimer lasers (preferably ArF excimer lasers).

In particular, at least one selected from the group consisting of a tricyclodecyl group, an adamantyl group, a tetracyclododecyl group, an isobornyl group, and a norbornyl group is preferable from the viewpoint of ease of industrial acquisition. These polycyclic groups may have a linear or branched alkyl group having 1 to 5 carbon atoms as a substituent.

As the constituent unit (a4), specifically, the constituent units represented by the following general formulas (a4-1) to (a4-7) can be exemplified.

[Chemical Formula 29]

[In the formula, R ^α is the same as above.]

(A1) The composition unit (a4) of the component may be one type or two or more types.

When the (A1) component has a structural unit (a4), the proportion of the structural unit (a4) among the (A1) component is preferably 1 to 30 mol%, more preferably 3 to 20 mol%, with respect to the total (100 mol%) of the entire structural units constituting the (A1) component.

By setting the ratio of the constituent unit (a4) to the lower limit of the above-mentioned preferable range or higher, the effect of containing the constituent unit (a4) is sufficiently obtained. On the other hand, by setting it to the upper limit of the above-mentioned preferable range or lower, it becomes easy to achieve a balance with other constituent units.

· A structural unit derived from styrene

When the (A1) component has a structural unit derived from styrene, the proportion of the structural unit derived from styrene in the (A1) component is preferably 1 to 30 mol%, more preferably 3 to 20 mol%, with respect to the total (100 mol%) of the structural units constituting the (A1) component.

In the resist composition of the embodiment, component (A) includes a polymer compound (A1) having a structural unit (a10) and a structural unit (a1).

As such (A1) components, a polymer compound having a repeating structure of the constituent unit (a10) and the constituent unit (a1) is preferable, and among these, a polymer compound having a repeating structure of the constituent unit (a10) and the constituent unit (a1) and a constituent unit derived from styrene is particularly preferable.

(A1) The weight average molecular weight (Mw) of the component (based on polystyrene conversion by gel permeation chromatography (GPC)) is preferably 5,000 to 20,000, more preferably 7,000 to 15,000, and still more preferably 8,000 to 13,000.

(A1) When the Mw of the component is equal to or less than the upper limit of the above-mentioned preferable range, it becomes easy to suppress the viscosity of the resist composition from becoming excessively high, and the applicability of the resist composition to the support is further improved. In addition, it becomes easy to have sufficient solubility in a resist solvent for use as a resist, and further, the sensitivity also becomes easy to be improved. On the other hand, when it is equal to or more than the lower limit of the above-mentioned preferable range, a thick resist film is easily formed. In addition, the dry etching resistance and the resist pattern cross-sectional shape become better.

(A1) The dispersion ratio (Mw/Mn) of the component is not particularly limited, and is preferably 1.0 to 4.0, more preferably 1.0 to 3.0, and particularly preferably 1.5 to 2.5. In addition, Mn represents the number average molecular weight.

The (A1) component contained in the resist composition may be used alone or in combination of two or more types.

(A) The proportion of component (A1) among the components is preferably 25 mass% or more, more preferably 50 mass% or more, still more preferably 75 mass% or more, and may be 100 mass%, relative to the total mass of component (A). When the proportion of component (A1) is equal to or greater than the lower limit of the above preferable range, a resist pattern having excellent lithography characteristics such as high sensitivity, resolution, dimensional uniformity (CDU) within the support surface (Shot), etc., is easily formed.

In the resist composition of the embodiment, the concentration of the polymer compound (A1) is preferably 15 to 50 mass%, more preferably 25 to 45 mass%, and still more preferably 30 to 40 mass%, with respect to the total amount of the resist composition (100 mass%).

When the concentration of the component (A1) in the resist composition is equal to or higher than the lower limit of the above-described preferable range, a thick resist film is easily formed, and on the other hand, when it is equal to or lower than the upper limit of the above-described preferable range, it is easy to suppress the viscosity of the resist composition from becoming excessively high.

In the resist composition of the present embodiment, component (A) may be used alone or in combination of two or more types.

In the resist composition of the present embodiment, the content of component (A) may be adjusted depending on the thickness of the resist film to be formed, etc.

＜(B) Component＞

The resist composition of the present embodiment further contains, in addition to component (A), an acid generator component (B) (hereinafter referred to as “component (B)”).

This (B) component contains a specific acid generator (B1), that is, an acid generator (B1) represented by the general formula (b1) described below (hereinafter also referred to as “(B1) component”). By containing the (B1) component, foaming during high-temperature baking is suppressed in forming a resist pattern. In addition, when forming a resist pattern, good sensitivity is easily maintained, and lithography characteristics (dimensional uniformity, etc.) are improved.

· (B1) About the ingredients

(B1) The component is an acid generator represented by the following general formula (b1).

[Chemical formula 30]

[In the formula, R ²⁰¹¹ , R ²⁰²¹ and R ²⁰³¹ each independently represent an aryl group which may have a substituent. Two or more of R ²⁰¹¹ , R ²⁰²¹ and R ²⁰³¹ may be combined with each other to form a ring together with the sulfur atom in the formula. X ^- represents a counter anion.]

In the above formula (b1), R ²⁰¹¹ , R ²⁰²¹ and R ²⁰³¹ each independently represent an aryl group which may have a substituent.

As the aryl group in R ²⁰¹¹ , R ²⁰²¹ and R ²⁰³¹ , an unsubstituted aryl group having 6 to 20 carbon atoms can be mentioned, and a phenyl group and a naphthyl group are preferable.

Substituents that may be present in the aryl group in R ²⁰¹¹ , R ²⁰²¹ and R ²⁰³¹ include, for example, an alkyl group, a halogen atom, a halogenated alkyl group, a carbonyl group, a cyano group, an amino group, an aryl group and groups represented by the following general formulae (ca-r-1) to (ca-r-7).

The alkyl group used as a substituent here is preferably an alkyl group having 1 to 5 carbon atoms, and a linear or branched alkyl group is preferable.

The halogenated alkyl group as a substituent here is preferably a halogenated alkyl group having 1 to 5 carbon atoms, and a linear or branched halogenated alkyl group is preferable.

The aryl group as a substituent here may be an aryl group having 6 to 20 carbon atoms, and a phenyl group or a naphthyl group is preferable.

[Chemical Formula 31]

[In the formula, R' ²⁰¹ is, each independently, a hydrogen atom, a cyclic group which may have a substituent, a chain-shaped alkyl group which may have a substituent, or a chain-shaped alkenyl group which may have a substituent.]

Among the above formulas (ca-r-1) to (ca-r-7), R' ²⁰¹ is each independently a hydrogen atom, a cyclic group which may have a substituent, a chain-shaped alkyl group which may have a substituent, or a chain-shaped alkenyl group which may have a substituent.

Cyclic groups which may have substituents:

The cyclic group is preferably a cyclic hydrocarbon group, and the cyclic hydrocarbon group may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group. The aliphatic hydrocarbon group means a hydrocarbon group that does not have aromaticity. In addition, the aliphatic hydrocarbon group may be saturated or unsaturated, and usually, it is preferable that it is saturated.

The aromatic hydrocarbon group in R' ²⁰¹ is a hydrocarbon group having an aromatic ring. The aromatic hydrocarbon group preferably has 3 to 30 carbon atoms, more preferably 5 to 30 carbon atoms, still more preferably 5 to 20 carbon atoms, particularly preferably 6 to 15 carbon atoms, and most preferably 6 to 10 carbon atoms. However, the carbon atoms do not include the carbon atoms in the substituent.

Specific examples of the aromatic ring possessed by the aromatic hydrocarbon group in R' ²⁰¹ include benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, or an aromatic heterocycle in which some of the carbon atoms constituting the aromatic ring are replaced with heteroatoms. Examples of the heteroatom in the aromatic heterocycle include an oxygen atom, a sulfur atom, a nitrogen atom, and the like.

Specific examples of the aromatic hydrocarbon group for R' ²⁰¹ include a group in which one hydrogen atom is removed from the aromatic ring (aryl group: for example, a phenyl group, a naphthyl group, etc.), a group in which one hydrogen atom of the aromatic ring is replaced by an alkylene group (for example, an arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, a 2-naphthylethyl group, etc.). The number of carbon atoms in the alkylene group (the alkyl chain in the arylalkyl group) is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1.

The cyclic aliphatic hydrocarbon group in R' ²⁰¹ may be an aliphatic hydrocarbon group containing a ring in its structure.

Among these structures, examples of aliphatic hydrocarbon groups containing a ring include an alicyclic hydrocarbon group (a group in which one hydrogen atom is removed from an aliphatic hydrocarbon ring), a group in which an alicyclic hydrocarbon group is bonded to the end of a linear or branched aliphatic hydrocarbon group, and a group in which an alicyclic hydrocarbon group is interposed in the middle of a linear or branched aliphatic hydrocarbon group.

The above-mentioned alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably has 3 to 12 carbon atoms.

The above-mentioned alicyclic hydrocarbon group may be a polycyclic group or a monocyclic group. As the monocyclic alicyclic hydrocarbon group, a group obtained by removing one or more hydrogen atoms from a monocycloalkane is preferable. As the monocycloalkane, a group having 3 to 6 carbon atoms is preferable, and specific examples thereof include cyclopentane and cyclohexane. As the polycyclic alicyclic hydrocarbon group, a group obtained by removing one or more hydrogen atoms from a polycycloalkane is preferable, and as the polycycloalkane, a group having 7 to 30 carbon atoms is preferable. Among these, as the polycycloalkane, a polycycloalkane having a polycyclic skeleton of a bridged ring system such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane; and a polycycloalkane having a polycyclic skeleton of a condensed ring system such as a cyclic group having a steroid skeleton are more preferable.

Among these, as the cyclic aliphatic hydrocarbon group for R' ²⁰¹ , a group in which at least one hydrogen atom has been removed from a monocycloalkane or a polycycloalkane is preferable, a group in which one hydrogen atom has been removed from a polycycloalkane is more preferable, an adamantyl group and a norbornyl group are particularly preferable, and an adamantyl group is most preferable.

The linear or branched aliphatic hydrocarbon group that may be bonded to an alicyclic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.

As the linear aliphatic hydrocarbon group, a linear alkylene group is preferable, and specific examples thereof include a methylene group [-CH ₂ -], an ethylene group [-(CH ₂ ) ₂ -], a trimethylene group [-(CH ₂ ) ₃ -], a tetramethylene group [-(CH ₂ ) ₄ -], a pentamethylene group [-(CH ₂ ) ₅ -], and the like.

As the branched-chain aliphatic hydrocarbon group, a branched-chain alkylene group is preferable, and specifically, alkylmethylene groups such as -CH(CH ₃ )-, -CH(CH ₂ CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CH ₃ )(CH ₂ CH ₃ )-, -C(CH ₃ )(CH ₂ CH ₂ CH ₃ )-, -C(CH ₂ CH ₃ ) ₂ -; alkylethylene groups such as -CH(CH ₃ )CH ₂ -, -CH(CH ₃ )CH(CH ₃ )-, -C(CH ₃ ) ₂ CH ₂ -, -CH(CH ₂ CH ₃ )CH ₂ -, -C(CH ₂ CH ₃ ) ₂ -CH ₂ -; Examples thereof include alkyltrimethylene groups such as -CH(CH ₃ )CH ₂ CH ₂ -, -CH ₂ CH(CH ₃ )CH ₂ -, and the like; alkylalkylene groups such as alkyltetramethylene groups such as -CH(CH ₃ )CH ₂ CH ₂ CH ₂ -, -CH ₂ CH(CH ₃ )CH ₂ CH ₂ -, and the like. As the alkyl group in the alkylalkylene group, a linear alkyl group having 1 to 5 carbon atoms is preferable.

In addition, the cyclic hydrocarbon group in R' ²⁰¹ may contain a heteroatom such as a heterocyclic ring. Specifically, examples thereof include lactone-containing cyclic groups represented by the general formulae (a2-r-1) to (a2-r-7) respectively, -SO ₂ - containing cyclic groups represented by the general formulae (a5-r-1) to (a5-r-4) respectively, and other heterocyclic groups represented by the chemical formulae (r-hr-1) to (r-hr-16) respectively.

[Chemical formula 32]

In addition, as a cyclic group that may have a substituent, the same acid-labile group represented by the formula (a1-r-2) described above can be mentioned.

Substituents in the cyclic group of R' ²⁰¹ include, for example, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, a nitro group, and the like.

As the alkyl group as a substituent, an alkyl group having 1 to 5 carbon atoms is preferable, and a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group is more preferable.

As an alkoxy group as a substituent, an alkoxy group having 1 to 5 carbon atoms is preferable, a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, a tert-butoxy group are more preferable, and a methoxy group and an ethoxy group are most preferable.

As a halogen atom as a substituent, examples include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc., and a fluorine atom is preferred.

As a halogenated alkyl group as a substituent, an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a tert-butyl group, etc., in which some or all of the hydrogen atoms are replaced with the halogen atoms, can be exemplified.

A carbonyl group as a substituent is a group that substitutes a methylene group (-CH ₂ -) that constitutes a cyclic hydrocarbon group.

Chain-shaped alkyl group which may have a substituent:

The chain-type alkyl group of R' ²⁰¹ may be either a straight chain or a branched chain.

As the linear alkyl group, those having 1 to 20 carbon atoms are preferable, those having 1 to 15 carbon atoms are more preferable, and those having 1 to 10 carbon atoms are most preferable. Specifically, examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decanyl group, an undecyl group, a dodecyl group, a tridecyl group, an isotridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, an isohexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, an icosyl group, a heneicosyl group, and a docosyl group.

As the branched chain alkyl group, those having 3 to 20 carbon atoms are preferable, those having 3 to 15 carbon atoms are more preferable, and those having 3 to 10 carbon atoms are most preferable. Specifically, examples thereof include a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, and a 4-methylpentyl group.

In addition, as a chain-shaped alkyl group that may have a substituent, the same acid-labile group represented by the formula (a1-r-2) described above can be mentioned.

Chain-shaped alkenyl group which may have a substituent:

The chain-shaped alkenyl group of R' ²⁰¹ may be either linear or branched, and preferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms, still more preferably 2 to 4 carbon atoms, and particularly preferably 3 carbon atoms. Examples of the linear alkenyl group include a vinyl group, a propenyl group (allyl group), a butynyl group, and the like. Examples of the branched alkenyl group include a 1-methylvinyl group, a 2-methylvinyl group, a 1-methylpropenyl group, and a 2-methylpropenyl group.

Among the chain-shaped alkenyl groups, a linear alkenyl group is preferable, a vinyl group or a propenyl group is more preferable, and a vinyl group is particularly preferable.

Substituents in the chain-shaped alkyl group or alkenyl group of R' ²⁰¹ include, for example, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, a nitro group, an amino group, and a cyclic group in the above R' ²⁰¹ .

Among the above, R' ²⁰¹ is preferably a cyclic group which may have a substituent, and more preferably a cyclic hydrocarbon group which may have a substituent. More specifically, it is preferably a phenyl group, a naphthyl group, a group in which one or more hydrogen atoms are removed from a polycycloalkane; a lactone-containing cyclic group represented by each of the general formulae (a2-r-1) to (a2-r-7); and a -SO ₂ - containing cyclic group represented by each of the general formulae (a5-r-1) to (a5-r-4). Among these, R' ²⁰¹ is more preferably a group in which one or more hydrogen atoms are removed from a polycycloalkane which may have a substituent.

In the (B1) component contained in the resist composition of the embodiment, it is preferable that at least one of R ²⁰¹¹ , R ²⁰²¹ and R ²⁰³¹ in the general formula (b1) is an aryl group having a substituent. When at least one of R ²⁰¹¹ , R ²⁰²¹ and R ²⁰³¹ is an aryl group having a substituent, not only is foaming easily suppressed during high-temperature baking, but solubility in organic solvents is increased, so that precipitation, etc., does not easily occur during development. In addition, the process margin during pattern formation is easily increased, and, for example, the depth of focus (DOF) characteristics are easily improved.

In this case, the substituents of the aryl groups in R ²⁰¹¹ , R ²⁰²¹ and R ²⁰³¹ are preferably at least one selected from the group consisting of an alkyl group, a halogen atom, a halogenated alkyl group, a carbonyl group, a cyano group, an amino group, an aryl group, and groups represented by the general formulae (ca-r-1) to (ca-r-7) above.

Two or more of the above R ²⁰¹¹ , R ²⁰²¹ and R ²⁰³¹ may be combined with each other to form a ring together with the sulfur atom in the formula.

When forming a ring in this way, a functional group such as a heteroatom such as a sulfur atom, an oxygen atom, or a nitrogen atom, a carbonyl group, -SO-, -SO ₂ -, -SO ₃ -, -COO-, -CONH-, or -N(R _N )- (wherein R _N is an alkyl group having 1 to 5 carbon atoms) may be involved in the bond.

Among the rings formed, one ring containing a sulfur atom in the formula in its ring skeleton is preferably a 3 to 10-membered ring including a sulfur atom, and is particularly preferably a 5 to 7-membered ring. Specific examples of the rings formed include a thiophene ring, a thiazole ring, a benzothiophene ring, a thianthrene ring, a benzothiophene ring, a dibenzothiophene ring, a 9H-thioxanthene ring, a thioxanthone ring, a thianthrene ring, a phenoxathiine ring, a tetrahydrothiophenium ring, a tetrahydrothiopyranium ring, and the like.

As a preferable cation in the acid generator represented by the above general formula (b1), specifically, cations represented by the following chemical formulas (ca-1-1) to (ca-1-55) can be mentioned.

[Chemical formula 33]

[Chemical Formula 34]

[Chemical Formula 35]

[In the formula, g1, g2, and g3 represent the number of repetitions, g1 is an integer from 1 to 5, g2 is an integer from 0 to 20, and g3 is an integer from 0 to 20.]

[Chemical formula 36]

In the above formula (b1), X ^- represents a counter anion.

As this ^X- , any anion known as an anion moiety of an acid generator component for a resist composition can be appropriately used without particular limitation.

For example, X ^- may be an anion represented by the general formula (b1-a1), an anion represented by the general formula (b1-a2), or an anion represented by the general formula (b1-a3).

[Chemical Formula 37]

[Wherein, R ¹⁰¹ , R ¹⁰⁴ ∼ R ¹⁰⁸ independently represent a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a chain-like alkenyl group which may have a substituent. R ¹⁰⁴ and R ¹⁰⁵ may be bonded to each other to form a ring. R ¹⁰² is a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms. Y ¹⁰¹ is a single bond or a divalent linking group containing an oxygen atom. V ¹⁰¹ ∼ V ¹⁰³ are each independently a single bond, an alkylene group, or a fluorinated alkylene group. L ¹⁰¹ ∼ L ¹⁰² are each independently a single bond or an oxygen atom. L ¹⁰³ ∼ L ¹⁰⁵ are each independently a single bond, -CO-, or -SO ₂ -.]

· Anion represented by general formula (b1-a1)

In formula (b1-a1), R ¹⁰¹ is a cyclic group which may have a substituent, a chain-shaped alkyl group which may have a substituent, or a chain-shaped alkenyl group which may have a substituent, and examples thereof include the same as R' ²⁰¹ in the formulas (ca-r-1) to (ca-r-7) above.

Among the above, R ¹⁰¹ is preferably a cyclic group which may have a substituent, and is more preferably a cyclic hydrocarbon group which may have a substituent. More specifically, a group in which one or more hydrogen atoms are removed from a phenyl group, a naphthyl group, a polycycloalkane; a lactone-containing cyclic group represented by each of the general formulae (a2-r-1) to (a2-r-7); a -SO ₂ - containing cyclic group represented by each of the general formulae (a5-r-1) to (a5-r-4), etc. are preferable.

In formula (b1-a1), Y ¹⁰¹ is a single bond or a divalent linking group containing an oxygen atom.

When Y ¹⁰¹ is a divalent linking group containing an oxygen atom, Y ¹⁰¹ may contain an atom other than an oxygen atom. Examples of the atom other than an oxygen atom include a carbon atom, a hydrogen atom, a sulfur atom, a nitrogen atom, and the like.

Examples of the divalent linking group containing an oxygen atom include non-hydrocarbon oxygen atom-containing linking groups such as an oxygen atom (ether bond: -O-), an ester bond (-C(=O)-O-), an oxycarbonyl group (-OC(=O)-), an amide bond (-C(=O)-NH-), a carbonyl group (-C(=O)-), a carbonate bond (-OC(=O)-O-); combinations of the non-hydrocarbon oxygen atom-containing linking groups and alkylene groups; and the like. A sulfonyl group (-SO ₂ -) may be further linked to this combination. Examples of such divalent linking groups containing an oxygen atom include linking groups represented by the following general formulae (y-al-1) to (y-al-7).

[Chemical formula 38]

[In the formula, V' ¹⁰¹ is a single bond or an alkylene group having 1 to 5 carbon atoms, and V' ¹⁰² is a divalent saturated hydrocarbon group having 1 to 30 carbon atoms.]

The divalent saturated hydrocarbon group in V' ¹⁰² is preferably an alkylene group having 1 to 30 carbon atoms, more preferably an alkylene group having 1 to 10 carbon atoms, and still more preferably an alkylene group having 1 to 5 carbon atoms.

The alkylene group in V' ¹⁰¹ and V' ¹⁰² may be a linear alkylene group or a branched alkylene group, and a linear alkylene group is preferable.

As the alkylene group in V' ¹⁰¹ and V' ¹⁰² , specifically, a methylene group [-CH ₂ -]; an alkylmethylene group such as -CH(CH ₃ )-, -CH(CH ₂ CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CH ₃ )(CH ₂ CH ₃ )-, -C(CH ₃ )(CH ₂ CH ₂ CH ₃ )-, -C(CH ₂ CH ₃ ) ₂ -; an ethylene group [-CH ₂ CH ₂ -]; an alkylethylene group such as -CH(CH ₃ )CH ₂ -, -CH(CH ₃ )CH(CH ₃ )-, -C(CH ₃ ) ₂ CH ₂ -, -CH(CH ₂ CH ₃ )CH ₂ -; a trimethylene group (n-propylene group) [-CH ₂ CH ₂ CH ₂ -]; Examples thereof include alkyltrimethylene groups such as -CH(CH ₃ )CH ₂ CH ₂ -, -CH ₂ CH(CH ₃ )CH ₂ -; tetramethylene group [-CH ₂ CH ₂ CH ₂ CH ₂ -]; alkyltetramethylene groups such as -CH(CH ₃ )CH ₂ CH ₂ CH ₂ -, -CH ₂ CH(CH ₃ )CH ₂ CH ₂ -; pentamethylene group [-CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ -], etc.

In addition, some of the methylene groups in the alkylene group in V' ¹⁰¹ or V' ¹⁰² may be substituted with a divalent aliphatic cyclic group having 5 to 10 carbon atoms. The aliphatic cyclic group is preferably a divalent group obtained by further removing one hydrogen atom from the cyclic aliphatic hydrocarbon group of Ra' ³ in the formula (a1-r-1) (monocyclic aliphatic hydrocarbon group, polycyclic aliphatic hydrocarbon group), and a cyclohexylene group, a 1,5-adamantylene group or a 2,6-adamantylene group is more preferable.

For Y ¹⁰¹ , a divalent linking group including an ester bond or a divalent linking group including an ether bond is preferable, and a linking group represented by each of the above formulae (y-al-1) to (y-al-5) is more preferable.

In formula (b1-a1), V ¹⁰¹ is a single bond, an alkylene group, or a fluorinated alkylene group. The alkylene group or fluorinated alkylene group in V ¹⁰¹ preferably has 1 to 4 carbon atoms. Examples of the fluorinated alkylene group in V ¹⁰¹ include a group in which some or all of the hydrogen atoms of the alkylene group in V ¹⁰¹ are replaced with fluorine atoms. Among these, V ¹⁰¹ is preferably a single bond or a fluorinated alkylene group having 1 to 4 carbon atoms.

In formula (b1-a1), R ¹⁰² is a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms. R ¹⁰² is preferably a fluorine atom or a perfluoroalkyl group having 1 to 5 carbon atoms, and is more preferably a fluorine atom.

Specific examples of the anion moiety represented by the above formula (b1-a1) include, for example, when Y ¹⁰¹ is a single bond, a fluorinated alkyl sulfonate anion such as a trifluoromethanesulfonate anion or a perfluorobutanesulfonate anion. When Y ¹⁰¹ is a divalent linking group containing an oxygen atom, anions represented by any of the following general formulae (an-1) to (an-3) can be mentioned.

[Chemical Formula 39]

[In the formula, R" ¹⁰¹ is an aliphatic cyclic group which may have a substituent, a group represented by each of the above formulas (r-hr-1) to (r-hr-6), or a chain-shaped alkyl group which may have a substituent. R" ¹⁰² is an aliphatic cyclic group which may have a substituent, a lactone-containing cyclic group represented by each of the above general formulas (a2-r-1) to (a2-r-7), or a -SO ₂ - containing cyclic group represented by each of the above general formulas (a5-r-1) to (a5-r-4). R" ¹⁰³ is an aromatic cyclic group which may have a substituent, an aliphatic cyclic group which may have a substituent, or a chain-shaped alkenyl group which may have a substituent. V" ¹⁰¹ is a single bond, an alkylene group having 1 to 4 carbon atoms, or a fluorinated alkylene group having 1 to 4 carbon atoms. R ¹⁰² is a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms. v" are each independently an integer of 0 to 3, q" are each independently an integer of 1 to 20, and n" is 0 or 1.]

The aliphatic cyclic group which may have a substituent of R" ¹⁰¹ , R" ¹⁰² and R" ¹⁰³ is preferably a group exemplified as the cyclic aliphatic hydrocarbon group for R ¹⁰¹ . Examples of the substituent include the same substituents as those which may substitute the cyclic aliphatic hydrocarbon group for R ¹⁰¹ .

The aromatic cyclic group which may have a substituent in R" ¹⁰³ is preferably a group exemplified as an aromatic hydrocarbon group in the cyclic hydrocarbon group in R ^101. Examples of the substituent include the same substituents as those which may substitute the aromatic hydrocarbon group in R ¹⁰¹ .

The chain-shaped alkyl group which may have a substituent in R" ¹⁰¹ is preferably a group exemplified as the chain-shaped alkyl group in R" ^101. The chain-shaped alkenyl group which may have a substituent in R" ¹⁰³ is preferably a group exemplified as the chain-shaped alkenyl group in R ^{" 101} .

In the above formulas (an-1) to (an-3), V" ¹⁰¹ is a single bond, an alkylene group having 1 to 4 carbon atoms, or a fluorinated alkylene group having 1 to 4 carbon atoms. V" ¹⁰¹ is preferably a single bond, an alkylene group (methylene group) having 1 carbon atoms, or a fluorinated alkylene group having 1 to 3 carbon atoms.

In the above formulas (an-1) to (an-3), R ¹⁰² is a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms. R ¹⁰² is preferably a perfluoroalkyl group having 1 to 5 carbon atoms or a fluorine atom, and is more preferably a fluorine atom.

In the above formulas (an-1) to (an-3), v" is an integer of 0 to 3, preferably 0 or 1. q" is an integer of 1 to 20, preferably an integer of 1 to 10, more preferably an integer of 1 to 5, even more preferably 1, 2 or 3, and particularly preferably 1 or 2. n" is 0 or 1.

· Anion represented by general formula (b1-a2)

In formula (b1-a2), R ¹⁰⁴ and R ¹⁰⁵ each independently represent a cyclic group which may have a substituent, a chain-shaped alkyl group which may have a substituent, or a chain-shaped alkenyl group which may have a substituent, and examples thereof include the same groups as R ¹⁰¹ in formula (b1-a1). However, R ¹⁰⁴ and R ¹⁰⁵ may be bonded to each other to form a ring.

R ¹⁰⁴ and R ¹⁰⁵ are preferably a chain-like alkyl group which may have a substituent, and are more preferably a linear or branched alkyl group, or a linear or branched fluorinated alkyl group.

The number of carbon atoms in the chain-shaped alkyl group is preferably 1 to 10, more preferably 1 to 7, and even more preferably 1 to 3. The number of carbon atoms in the chain-shaped alkyl group of R ¹⁰⁴ and R ¹⁰⁵ is preferably smaller within the above-mentioned carbon number range, for reasons such as better solubility in a resist solvent, and the like. In addition, in the chain-shaped alkyl group of R ¹⁰⁴ and R ¹⁰⁵ , the greater the number of hydrogen atoms substituted with fluorine atoms, the stronger the acid strength becomes, which is preferable.

The ratio of fluorine atoms in the above chain-shaped alkyl group, i.e., the fluorination rate, is preferably 70 to 100%, more preferably 90 to 100%, and most preferably, it is a perfluoroalkyl group in which all hydrogen atoms are replaced with fluorine atoms.

In formula (b1-a2), V ¹⁰² and V ¹⁰³ are each independently a single bond, an alkylene group or a fluorinated alkylene group, and each may be the same as V ¹⁰¹ in formula (b1-a1).

In formula (b1-a2), L ¹⁰¹ and L ¹⁰² are each independently a single bond or an oxygen atom.

· Anion represented by general formula (b1-a3)

In formula (b1-a3), R ¹⁰⁶ to R ¹⁰⁸ are each independently a cyclic group which may have a substituent, a chain-shaped alkyl group which may have a substituent, or a chain-shaped alkenyl group which may have a substituent, and examples thereof include the same groups as R ¹⁰¹ in formula (b1-a1).

In formula (b1-a3), L ¹⁰³ to L ¹⁰⁵ are each independently a single bond, -CO- or -SO ₂ -.

Among the above, as the anion part of the (B1) component, an anion represented by the general formula (b1-a1) is preferable. When the (B1) component having this anion as the anion part is used, the dimensional uniformity within the support surface is further improved in forming a resist pattern. For example, when a space-and-line pattern is formed, the deviation in the dimension (CD) of the space width is small, and a pattern of uniform width is easily formed with high precision.

Among these anions, an anion represented by any of the general formulae (an-1) to (an-3) is more preferable, an anion represented by any of the general formulae (an-1) or (an-2) is even more preferable, and an anion represented by the general formula (an-1) is particularly preferable.

Specific examples of preferred (B1) components are given below.

[Chemical formula 40]

The (B1) component contained in the resist composition may be used alone or in combination of two or more types.

(B) The ratio of the (B1) component among the components is preferably 50 mass% or more, more preferably 75 mass% or more, and may be 100 mass%, with respect to the total mass of the (B) component. When the ratio of the (B1) component is equal to or greater than the lower limit of the above preferable range, foaming during high-temperature baking is further suppressed. In addition, when forming a resist pattern, good sensitivity is easily maintained, and lithography characteristics (such as dimensional uniformity) are improved.

In the resist composition of the present embodiment, the content of component (B1) is preferably 1 to 40 parts by mass, more preferably 1.5 to 35 parts by mass, and even more preferably 2 to 30 parts by mass, relative to 100 parts by mass of component (A).

(B1) When the content of the component is equal to or higher than the lower limit of the above preferable range, foaming during high-temperature baking is more suppressed. In addition, when forming a resist pattern, good sensitivity is easily maintained, and lithography characteristics (dimensional uniformity, etc.) are improved. On the other hand, when it is equal to or lower than the upper limit of the above preferable range, when each component of the resist composition is dissolved in an organic solvent, a uniform solution is easily obtained, and the storage stability as a resist composition is further improved.

· (B2) About the ingredients

The resist composition of the present embodiment may contain an acid generator component other than the component (B1) (hereinafter referred to as “component (B2)”), as long as it does not impair the effects of the present invention.

(B2) As a component, there is no particular limitation, and any of those proposed so far as acid generators for chemically amplified resist compositions can be used.

Examples of such acid generators include onium salt-based acid generators such as iodonium salts or sulfonium salts; oxime sulfonate-based acid generators; diazomethane-based acid generators such as bisalkyl or bisarylsulfonyldiazomethanes and poly(bissulfonyl)diazomethanes; nitrobenzylsulfonate-based acid generators, iminosulfonate-based acid generators, disulfone-based acid generators, and the like.

Examples of the onium salt-based acid generator include a compound represented by the following general formula (b-1) (hereinafter also referred to as the “(b-1) component”), a compound represented by the following general formula (b-2) (hereinafter also referred to as the “(b-2) component”), or a compound represented by the following general formula (b-3) (hereinafter also referred to as the “(b-3) component”).

[Chemical Formula 41]

[Wherein, R ¹⁰¹ , R ¹⁰⁴ ∼ R ¹⁰⁸ independently represent a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a chain-like alkenyl group which may have a substituent. R ¹⁰⁴ and R ¹⁰⁵ may be bonded to each other to form a ring. R ¹⁰² is a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms. Y ¹⁰¹ is a single bond or a divalent linking group containing an oxygen atom. V ¹⁰¹ ∼ V ¹⁰³ are each independently a single bond, an alkylene group, or a fluorinated alkylene group. L ¹⁰¹ ∼ L ¹⁰² are each independently a single bond or an oxygen atom. L ¹⁰³ ∼ L ¹⁰⁵ are each independently a single bond, -CO-, or -SO ₂ -. m is an integer greater than or equal to 1, and M' ^{m +} is an onium cation of valence m.]

{Anion Department}

(b-1) The anion part of the component is identical to the anion represented by the general formula (b1-a1) described above.

(b-2) The anion part of the component is identical to the anion represented by the general formula (b1-a2) described above.

(b-3) The anion part of the component is identical to the anion represented by the general formula (b1-a3) described above.

{Cation section}

In the above formulas (b-1), (b-2), and (b-3), M' ^{m +} represents an onium cation having a valence of m (however, the cation corresponding to the cation portion in the above general formula (b1) is excluded). Among these, a sulfonium cation and an iodonium cation are preferable.

m is an integer greater than or equal to 1.

As a preferable cation moiety ((M' ^{m +} ) _1/m ), organic cations represented by the following general formulas (ca-1) to (ca-4) can be mentioned.

[Chemical formula 42]

[In the formula, R ²⁰¹ to R ²⁰⁷ and R ²¹¹ to R ²¹² independently represent an aryl group, an alkyl group or an alkenyl group which may have a substituent. R ²⁰¹ to R ²⁰³ , R ²⁰⁶ to R ²⁰⁷ and R ²¹¹ to R ²¹² may be bonded to each other to form a ring together with the sulfur atom in the formula. R ²⁰⁸ to R ²⁰⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ²¹⁰ is an aryl group which may have a substituent, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, or a -SO ₂ -containing cyclic group which may have a substituent. L ²⁰¹ represents -C(=O)- or -C(=O)-O-. Y ²⁰¹ each independently represents an arylene group, an alkylene group, or an alkenylene group. x is 1 or 2. W ²⁰¹ represents a linking group of (x + 1).]

Among the general formulas (ca-1) to (ca-4) above, the aryl group in R ²⁰¹ to R ²⁰⁷ and R ²¹¹ to R ²¹² includes an unsubstituted aryl group having 6 to 20 carbon atoms, and a phenyl group and a naphthyl group are preferable.

The alkyl group for R ²⁰¹ to R ²⁰⁷ and R ²¹¹ to R ²¹² is preferably a chain-shaped or cyclic alkyl group having 1 to 30 carbon atoms.

As for the alkenyl group in R ²⁰¹ to R ²⁰⁷ and R ²¹¹ to R ²¹² , those having 2 to 10 carbon atoms are preferable.

Substituents that may be present in R ²⁰¹ to R ²⁰⁷ and R ²¹⁰ to R ²¹² include, for example, an alkyl group, a halogen atom, a halogenated alkyl group, a carbonyl group, a cyano group, an amino group, an aryl group, and groups represented by the general formulae (ca-r-1) to (ca-r-7) above, respectively.

In the above general formulas (ca-1) to (ca-4), when R ²⁰¹ to R ²⁰³ , R ²⁰⁶ to R ²⁰⁷ , and R ²¹¹ to R ²¹² are bonded to each other to form a ring with the sulfur atom in the formula, they may be bonded via a heteroatom such as a sulfur atom, an oxygen atom, or a nitrogen atom, or a functional group such as a carbonyl group, -SO-, -SO ₂ -, -SO ₃ -, -COO-, -CONH-, or -N(R _N )- (wherein R _N is an alkyl group having 1 to 5 carbon atoms). Among the rings formed, one ring containing the sulfur atom in the formula in its ring skeleton is preferably a 3 to 10-membered ring including the sulfur atom, and is particularly preferably a 5 to 7-membered ring. Specific examples of the rings formed include, for example, a thiophene ring, a thiazole ring, a benzothiophene ring, a thianthrene ring, a benzothiophene ring, a dibenzothiophene ring, a 9H-thioxanthene ring, a thioxanthone ring, a thianthrene ring, a phenoxathiine ring, a tetrahydrothiophenium ring, a tetrahydrothiopyranium ring, and the like.

R ²⁰⁸ to R ²⁰⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and when they are alkyl groups, they may be bonded to each other to form a ring.

R ²¹⁰ is an aryl group which may have a substituent, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, or a -SO ₂ - containing cyclic group which may have a substituent.

As the aryl group in R ²¹⁰ , an unsubstituted aryl group having 6 to 20 carbon atoms can be mentioned, and a phenyl group or a naphthyl group is preferable.

As the alkyl group in R ²¹⁰ , a chain-shaped or cyclic alkyl group having 1 to 30 carbon atoms is preferable.

As for the alkenyl group in R ²¹⁰ , one having 2 to 10 carbon atoms is preferable.

As the -SO ₂ -containing cyclic group which may have a substituent in R ²¹⁰ , a "-SO ₂ -containing polycyclic group" is preferable, and a group represented by the above general formula (a5-r-1) is more preferable.

Y ²⁰¹ each independently represents an arylene group, an alkylene group, or an alkenylene group.

The arylene group in Y ²⁰¹ can be a group having one hydrogen atom removed from the aryl group exemplified as the aromatic hydrocarbon group in R ¹⁰¹ in the formula (b1-a1) described above.

The alkylene group and alkenylene group in Y ²⁰¹ include groups having one hydrogen atom removed from the chain-shaped alkyl group and chain-shaped alkenyl group in R ¹⁰¹ in the formula (b1-a1) described above.

In the above formula (ca-4), x is 1 or 2.

W ²⁰¹ is a connector of (x + 1), i.e., divalent or trivalent.

As the divalent linking group in W ²⁰¹ , a divalent hydrocarbon group which may have a substituent is preferable, and examples thereof include the same divalent hydrocarbon group which may have a substituent as Ya ²¹ in the general formula (a2-1) described above. The divalent linking group in W ²⁰¹ may be any of a linear, branched, or cyclic type, and a cyclic type is preferable. Among these, a group in which two carbonyl groups are combined at both ends of an arylene group is preferable. Examples of the arylene group include a phenylene group, a naphthylene group, and the like, and a phenylene group is particularly preferable.

Examples of the trivalent linking group in W ²⁰¹ include a group having one hydrogen atom removed from the divalent linking group in W ²⁰¹ , a group having another divalent linking group bonded to the divalent linking group, and the like. The trivalent linking group in W ²⁰¹ is preferably a group having two carbonyl groups bonded to an arylene group.

As a preferable cation represented by the above formula (ca-1), specifically, cations represented by the following chemical formulas (ca-1-56) to (ca-1-71) can be mentioned.

[Chemical Formula 43]

[Chemical Formula 44]

[In the formula, R" ²⁰¹ is a hydrogen atom or a substituent, and the substituent is the same as the substituents that may be included in R ²⁰¹ to R ²⁰⁷ and R ²¹⁰ to R ^212. ]

Specific examples of preferred cations represented by the above formula (ca-2) include diphenyliodonium cation, bis(4-tert-butylphenyl)iodonium cation, etc.

As a preferable cation represented by the above formula (ca-3), specifically, cations represented by the following formulas (ca-3-1) to (ca-3-6) can be mentioned.

[Chemical Formula 45]

As a preferable cation represented by the above formula (ca-4), specifically, cations represented by the following formulas (ca-4-1) to (ca-4-2) can be mentioned.

[Chemical Formula 46]

Among the above, the cation portion ((M' ^{m +} ) _1/m ) is preferably a cation represented by the general formula (ca-1).

In the resist composition of the present embodiment, one type of component (B2) may be used alone, or two or more types may be used in combination.

When the resist composition contains component (B2), the content of component (B2) in the resist composition is preferably less than 50 parts by mass, more preferably 1 to 20 parts by mass, and even more preferably 1 to 10 parts by mass, with respect to 100 parts by mass of component (A).

(B2) By setting the content of the component within the above preferred range, pattern formation is sufficiently carried out. In addition, when each component of the resist composition is dissolved in an organic solvent, it is easy to obtain a uniform solution, and the preservation stability as a resist composition is improved, which is preferable.

＜(S) Ingredients＞

In the resist composition of the present embodiment, the organic solvent component (S) ((S) component) may be any solvent that can dissolve each of the blended components to form a uniform solution, and any solvent known in the art for chemically amplified resist compositions may be appropriately selected and used.

(S) As the component, for example, lactones such as γ-butyrolactone; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone, methyl isopentyl ketone, and 2-heptanone; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol; compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, or dipropylene glycol monoacetate; derivatives of polyhydric alcohols such as monoalkyl ethers such as monomethyl ether, monoethyl ether, monopropyl ether, and monobutyl ether of the above polyhydric alcohols or compounds having an ester bond, or compounds having an ether bond such as monophenyl ether [of these, propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are preferable]; cyclic ethers such as dioxane; Esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, and ethyl ethoxypropionate; aromatic organic solvents such as anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetole, butyl phenyl ether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, and mesitylene; and dimethyl sulfoxide (DMSO).

In the resist composition of the present embodiment, the component (S) may be used alone or as a mixed solvent of two or more types.

Among the above, as the (S) component, PGMEA, PGME, γ-butyrolactone, EL, and cyclohexanone are preferable.

In addition, a mixed solvent of PGMEA and a polar solvent is also preferable. The mixing ratio (mass ratio) may be appropriately determined by considering the compatibility of PGMEA and the polar solvent, etc., but is preferably within the range of 1:9 to 9:1, more preferably within the range of 2:8 to 8:2.

More specifically, when blending EL or cyclohexanone as a polar solvent, the mass ratio of PGMEA: EL or cyclohexanone is preferably 1:9 to 9:1, more preferably 2:8 to 8:2. Furthermore, when blending PGME as a polar solvent, the mass ratio of PGMEA: PGME is preferably 1:9 to 9:1, more preferably 2:8 to 8:2. Furthermore, a mixed solvent of PGMEA, PGME, and cyclohexanone is also preferable.

In addition, as the (S) component, a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mass ratio of the former and the latter is preferably 70:30 to 95:5 as the mixing ratio.

In the resist composition of the present embodiment, the (S) component is used so that the solid concentration in the resist composition is 30 mass% or more. That is, the solid concentration in the resist composition is 30 mass% or more, preferably 30 to 50 mass%, and more preferably 30 to 40 mass%.

When the solid concentration is equal to or higher than the lower limit of the above range, it becomes easy to uniformly form a thick resist film on the support. On the other hand, when it is equal to or lower than the upper limit of the above preferred range, the viscosity of the resist composition is reduced, and the applicability to the support, etc., is improved.

In addition, the concentration of the polymer compound (A1) in the total solid content of the resist composition of the present embodiment is preferably 90 mass% or more, more preferably 90 to 99 mass%, and still more preferably 95 to 99 mass%.

When the concentration of the (A1) component in the entire solid content is equal to or higher than the lower limit of the above preferable range, a thick resist film can be easily formed on the support.

＜Random ingredients＞

The resist composition of the present embodiment may additionally contain a component (optional component) other than the component (A), component (B), and component (S) described above.

Such optional components include, for example, the (D) component, the (E) component, and the (F) component shown below.

≪(D) Component: Acid diffusion control agent component≫

(D) The component acts as a quencher (acid diffusion control agent) that traps acid generated by exposure in the resist composition.

(D) As the component, examples thereof include a photodegradable base (D1) (hereinafter referred to as “(D1) component”) that decomposes upon exposure and loses acid diffusion controllability, a nitrogen-containing organic compound (D2) that does not correspond to the (D1) component (hereinafter referred to as “(D2) component”), etc.

· (D1) About the ingredients

By using a resist composition containing the (D1) component, when forming a resist pattern, the contrast between the exposed portion and the unexposed portion of the resist film can be further improved.

The (D1) component is not particularly limited as long as it decomposes by exposure and loses acid diffusion controllability, and is preferably at least one compound selected from the group consisting of a compound represented by the following general formula (d1-1) (hereinafter referred to as “(d1-1) component”), a compound represented by the following general formula (d1-2) (hereinafter referred to as “(d1-2) component”), and a compound represented by the following general formula (d1-3) (hereinafter referred to as “(d1-3) component”).

Components (d1-1) to (d1-3) do not act as quenchers because they decompose and lose acid diffusion controllability (basicity) in the exposed portion of the resist film, but act as quenchers in the unexposed portion of the resist film.

[Chemical formula 47]

[In the formula, Rd ¹ to Rd ⁴ are a cyclic group which may have a substituent, a chain-shaped alkyl group which may have a substituent, or a chain-shaped alkenyl group which may have a substituent. However, in Rd ² in the formula (d1-2), no fluorine atom is bonded to the carbon atom adjacent to the S atom. Yd ¹ is a single bond or a divalent linking group. m is an integer greater than or equal to 1, and M ^m+ are each independently an organic cation having a valence of m.]

{(d1-1) component}

·· No, not the Anion Department

In formula (d1-1), Rd ¹ is a cyclic group which may have a substituent, a chain-shaped alkyl group which may have a substituent, or a chain-shaped alkenyl group which may have a substituent, and examples thereof include the same as R ¹⁰¹ in formula (b1-a1).

Among these, as Rd ¹ , an aromatic hydrocarbon group which may have a substituent, an aliphatic cyclic group which may have a substituent, or a chain-shaped alkyl group which may have a substituent is preferable. Examples of the substituent which these groups may have include a hydroxyl group, an oxo group, an alkyl group, an aryl group, a fluorine atom, a fluorinated alkyl group, a lactone-containing cyclic group represented by each of the general formulae (a2-r-1) to (a2-r-7), an ether bond, an ester bond, or a combination thereof. When an ether bond or an ester bond is included as a substituent, an alkylene group may be interposed, and the substituent in this case is preferably a linking group represented by each of the formulae (y-al-1) to (y-al-5).

Among the above aromatic hydrocarbon groups, a phenyl group or a naphthyl group is more preferable.

As the above aliphatic cyclic group, it is more preferable that it is a group in which at least one hydrogen atom is removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane.

As the above-mentioned chain-shaped alkyl group, those having 1 to 10 carbon atoms are preferable, and specific examples thereof include linear alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group; and branched-chain alkyl groups such as a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, and a 4-methylpentyl group.

When the above chain-shaped alkyl group is a fluorinated alkyl group having a fluorine atom or a fluorinated alkyl group as a substituent, the fluorinated alkyl group preferably has 1 to 11 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 4 carbon atoms. The fluorinated alkyl group may contain atoms other than a fluorine atom. Examples of the atoms other than a fluorine atom include an oxygen atom, a sulfur atom, a nitrogen atom, and the like.

As for Rd ¹ , it is preferable that it is a fluorinated alkyl group in which some or all of the hydrogen atoms constituting the linear alkyl group are replaced by fluorine atoms, and it is particularly preferable that it is a fluorinated alkyl group in which all of the hydrogen atoms constituting the linear alkyl group are replaced by fluorine atoms (a linear perfluoroalkyl group).

Below, preferred specific examples of the anion portion of the (d1-1) component are shown.

[Chemical formula 48]

·· Cation section

In formula (d1-1), M ^m＋ is an organic cation of valence m.

As the organic cation of M ^m＋ , the same cations as those represented by the general formulae (ca-1) to (ca-4) are preferably mentioned, the cation represented by the general formula (ca-1) is more preferable, and the cations represented by the general formulae (ca-1-1) to (ca-1-71) are further preferable.

(d1-1) One component may be used alone, or two or more components may be used in combination.

{(d1-2) component}

·· No, not the Anion Department

In formula (d1-2), Rd ² is a cyclic group which may have a substituent, a chain-shaped alkyl group which may have a substituent, or a chain-shaped alkenyl group which may have a substituent, and examples thereof include the same as R ¹⁰¹ in formula (b1-a1).

However, in Rd ² , the carbon atom adjacent to the S atom is not bonded to a fluorine atom (is not substituted with fluorine). As a result, the anion of the (d1-2) component becomes a suitable weak acid anion, and the quenching ability as the (D) component is improved.

As Rd ² , it is preferable that it is a chain-shaped alkyl group which may have a substituent, or an aliphatic cyclic group which may have a substituent. As the chain-shaped alkyl group, it is preferable that it has 1 to 10 carbon atoms, and more preferably 3 to 10 carbon atoms. As the aliphatic cyclic group, it is a group obtained by removing one or more hydrogen atoms from adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane, etc. (which may have a substituent); it is more preferable that it is a group obtained by removing one or more hydrogen atoms from camphor, etc.

The hydrocarbon group of Rd ² may have a substituent, and examples of the substituent include the same substituents as those that the hydrocarbon group (aromatic hydrocarbon group, aliphatic cyclic group, chain-shaped alkyl group) of Rd ¹ of the above formula (d1-1) may have.

Below, preferred specific examples of the anion portion of the (d1-2) component are shown.

[Chemical Formula 49]

·· Cation section

In formula (d1-2), M ^m+ is an organic cation with valence m and is the same as M ^m+ in formula (d1-1).

(d1-2) One component may be used alone, or two or more components may be used in combination.

{(d1-3) components}

·· No, not the Anion Department

In formula (d1-3), Rd ³ is a cyclic group which may have a substituent, a chain-shaped alkyl group which may have a substituent, or a chain-shaped alkenyl group which may have a substituent, and examples thereof include the same as R ¹⁰¹ in formula (b1-a1), and it is preferably a cyclic group, chain-shaped alkyl group, or chain-shaped alkenyl group containing a fluorine atom. Among these, a fluorinated alkyl group is preferable, and the same as the fluorinated alkyl group of Rd ¹ is more preferable.

In formula (d1-3), Rd ⁴ is a cyclic group which may have a substituent, a chain-shaped alkyl group which may have a substituent, or a chain-shaped alkenyl group which may have a substituent, and examples thereof include the same as R ¹⁰¹ in formula (b1-a1).

Among these, an alkyl group, an alkoxy group, an alkenyl group, or a cyclic group that may have a substituent is preferable.

The alkyl group in Rd ⁴ is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and the like. Some of the hydrogen atoms in the alkyl group in Rd ⁴ may be substituted with a hydroxyl group, a cyano group, or the like.

The alkoxy group in Rd ⁴ is preferably an alkoxy group having 1 to 5 carbon atoms, and specific examples of the alkoxy group having 1 to 5 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, and a tert-butoxy group. Among these, a methoxy group and an ethoxy group are preferable.

The alkenyl group in Rd ⁴ may be the same as R ¹⁰¹ in the above formula (b1-a1), and a vinyl group, a propenyl group (allyl group), a 1-methylpropenyl group, or a 2-methylpropenyl group are preferable. These groups may further have an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms as a substituent.

The cyclic group in Rd ⁴ can be the same as R ¹⁰¹ in the above formula (b1-a1), and is preferably an alicyclic group in which one or more hydrogen atoms are removed from a cycloalkane such as cyclopentane, cyclohexane, adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane, or an aromatic group such as a phenyl group or a naphthyl group. When Rd ⁴ is an alicyclic group, the resist composition dissolves well in an organic solvent, thereby improving lithography characteristics. Furthermore, when Rd ⁴ is an aromatic group, the resist composition has excellent light absorption efficiency, and has good sensitivity and lithography characteristics.

In formula (d1-3), Yd ¹ is a single bond or a divalent linking group.

As the divalent linking group in Yd ¹ , examples thereof include, but are not particularly limited to, a divalent hydrocarbon group (aliphatic hydrocarbon group, aromatic hydrocarbon group) which may have a substituent, a divalent linking group containing a hetero atom, and the like. These can be the same as the divalent hydrocarbon group which may have a substituent, and the divalent linking group containing a hetero atom, which are exemplified in the explanation of the divalent linking group in Ya ^x1 in the general formula (a10-1) described above.

As for Yd ¹ , it is preferable that it is a carbonyl group, an ester bond, an amide bond, an alkylene group or a combination thereof. As the alkylene group, it is more preferable that it is a linear or branched alkylene group, and it is still more preferable that it is a methylene group or an ethylene group.

Below, preferred specific examples of the anion portion of the (d1-3) component are shown.

[Chemical formula 50]

[Chemical Formula 51]

·· Cation section

In formula (d1-3), M ^m+ is an organic cation with valence m and is the same as M ^m+ in formula (d1-1).

(d1-3) One component may be used alone, or two or more components may be used in combination.

(D1) Component may use only one of the components (d1-1) to (d1-3) above, or may use two or more of them in combination.

When the resist composition contains component (D1), the content of component (D1) in the resist composition is preferably 0.5 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, and still more preferably 1 to 8 parts by mass, with respect to 100 parts by mass of component (A).

(D1) When the content of the component is equal to or greater than the lower limit of the above-described preferable range, particularly good lithography characteristics and resist pattern shape are easily obtained. On the other hand, when it is equal to or less than the upper limit of the above-described preferable range, sensitivity can be maintained well and throughput is also excellent.

· (D2) About the component

As a component of the acid diffusion control agent, a nitrogen-containing organic compound component that does not correspond to the above (D1) component (hereinafter referred to as “component (D2)”) may be contained.

(D2) As a component, it acts as an acid diffusion control agent, and furthermore, as long as it does not correspond to the (D1) component, it is not particularly limited and any known component may be used arbitrarily. Among these, an aliphatic amine is preferable, and among these, a secondary aliphatic amine or a tertiary aliphatic amine is more preferable.

An aliphatic amine is an amine having one or more aliphatic groups, and it is preferable that the aliphatic groups have 1 to 12 carbon atoms.

As aliphatic amines, examples thereof include amines (alkylamines or alkylalcoholamines) or cyclic amines in which at least one hydrogen atom of ammonia _NH3 is replaced with an alkyl group or hydroxyalkyl group having 12 or fewer carbon atoms.

Specific examples of alkylamines and alkylalcoholamines include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, and n-decylamine; dialkylamines such as diethylamine, di-n-propylamine, di-n-heptylamine, di-n-octylamine, and dicyclohexylamine; trialkylamines such as trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine (triamylamine), tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decylamine, and tri-n-dodecylamine; and alkylalcoholamines such as diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, di-n-octanolamine, and tri-n-octanolamine. Among these, trialkylamines having 5 to 10 carbon atoms are more preferable, and tri-n-pentylamine or tri-n-octylamine is particularly preferable.

As a cyclic amine, for example, a heterocyclic compound containing a nitrogen atom as a heteroatom can be mentioned. The heterocyclic compound can be monocyclic (aliphatic monocyclic amine) or polycyclic (aliphatic polycyclic amine).

As aliphatic monocyclic amines, specific examples include piperidine and piperazine.

As the aliphatic polycyclic amine, those having 6 to 10 carbon atoms are preferable, and specific examples thereof include 1,5-diazabicyclo[4.3.0]-5-nonene, 1,8-diazabicyclo[5.4.0]-7-undecene, hexamethylenetetramine, and 1,4-diazabicyclo[2.2.2]octane.

Other aliphatic amines include tris(2-methoxymethoxyethyl)amine, tris{2-(2-methoxyethoxy)ethyl}amine, tris{2-(2-methoxyethoxymethoxy)ethyl}amine, tris{2-(1-methoxyethoxy)ethyl}amine, tris{2-(1-ethoxyethoxy)ethyl}amine, tris{2-(1-ethoxypropoxy)ethyl}amine, tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine, and triethanolamine triacetate, with triethanolamine triacetate being preferred.

Additionally, as the (D2) component, an aromatic amine may be used.

Aromatic amines include 4-dimethylaminopyridine, pyrrole, indole, pyrazole, imidazole or derivatives thereof, tribenzylamine, 2,6-diisopropylaniline, N-tert-butoxycarbonylpyrrolidine, etc.

(D2) One component may be used alone, or two or more components may be used in combination.

When the resist composition contains component (D2), the content of component (D2) in the resist composition is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of component (A). By setting the content of component (D2) within the above preferred range, the resist pattern shape, stability over time after exposure, etc. are improved.

≪(E) Component: At least one compound selected from the group consisting of organic carboxylic acids and phosphorus oxo acids and their derivatives≫

The resist composition of the present embodiment may contain, as an optional component, at least one compound (E) selected from the group consisting of organic carboxylic acids, phosphorus oxo acids and derivatives thereof (hereinafter referred to as “component (E)”) for the purpose of preventing sensitivity deterioration or improving the resist pattern shape, time-lapse stability after exposure, etc.

As organic carboxylic acids, for example, acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid, etc. are preferable.

Examples of oxoacids of phosphorus include phosphoric acid, phosphonic acid, and phosphinic acid, and among these, phosphonic acid is particularly preferable.

As derivatives of oxo acids of phosphorus, examples thereof include esters in which hydrogen atoms of the oxo acids are substituted with hydrocarbon groups, and examples of the hydrocarbon groups include alkyl groups having 1 to 5 carbon atoms, aryl groups having 6 to 15 carbon atoms, and the like.

Derivatives of phosphoric acid include phosphoric acid esters such as di-n-butyl phosphate and diphenyl phosphate.

Derivatives of phosphonic acid include phosphonic acid esters such as phosphonic acid dimethyl ester, phosphonic acid-di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, and phosphonic acid dibenzyl ester.

Derivatives of phosphinic acid include phosphinic acid esters and phenylphosphinic acid.

In the resist composition of the present embodiment, component (E) may be used alone or in combination of two or more types.

When the resist composition contains component (E), the content of component (E) is preferably in the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of component (A).

≪(F) Component: Fluorine additive component≫

The resist composition of the present embodiment may contain a fluorine additive component (hereinafter referred to as “component (F)”) in order to impart water repellency to the resist film or to improve lithography characteristics.

(F) As the component, for example, a fluorinated polymer compound described in Japanese Patent Application Laid-Open No. 2010-002870, Japanese Patent Application Laid-Open No. 2010-032994, Japanese Patent Application Laid-Open No. 2010-277043, Japanese Patent Application Laid-Open No. 2011-13569, and Japanese Patent Application Laid-Open No. 2011-128226 can be used.

(F) More specifically, as the component, a polymer having a structural unit (f1) represented by the following formula (f1-1) can be exemplified. The polymer is preferably a polymer (homopolymer) composed solely of the structural unit (f1) represented by the following formula (f1-1); a copolymer of the structural unit (f1) and the structural unit (a1); and a copolymer of the structural unit (f1) and a structural unit derived from acrylic acid or methacrylic acid and the structural unit (a1). Here, the structural unit (a1) copolymerized with the structural unit (f1) is preferably a structural unit derived from 1-ethyl-1-cyclooctyl (meth) acrylate or a structural unit derived from 1-methyl-1-adamantyl (meth) acrylate.

[Chemical formula 52]

[In the formula, R is the same as defined above, Rf ¹⁰² and Rf ¹⁰³ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms, and Rf ¹⁰² and Rf ¹⁰³ may be the same or different. nf ¹ is an integer of 1 to 5, and Rf ¹⁰¹ is an organic group containing a fluorine atom.]

In formula (f1-1), R bonded to the carbon atom at the α position is the same as above. As R, a hydrogen atom or a methyl group is preferable.

In formula (f1-1), examples of the halogen atom of Rf ¹⁰² and Rf ¹⁰³ include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like, and a fluorine atom is particularly preferable. Examples of the alkyl group having 1 to 5 carbon atoms of Rf ¹⁰² and Rf ¹⁰³ include the same groups as the alkyl group having 1 to 5 carbon atoms of R, and a methyl group or an ethyl group is preferable. Specific examples of the halogenated alkyl group having 1 to 5 carbon atoms of Rf ¹⁰² and Rf ¹⁰³ include groups in which some or all of the hydrogen atoms of the alkyl group having 1 to 5 carbon atoms are replaced with halogen atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like, and a fluorine atom is particularly preferable. Among these, as Rf ¹⁰² and Rf ¹⁰³ , a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 5 carbon atoms is preferable, and a hydrogen atom, a fluorine atom, a methyl group, or an ethyl group is preferable.

In formula (f1-1), nf ¹ is an integer from 1 to 5, preferably an integer from 1 to 3, and more preferably 1 or 2.

In formula (f1-1), Rf ¹⁰¹ is an organic group containing a fluorine atom, and is preferably a hydrocarbon group containing a fluorine atom.

The hydrocarbon group containing a fluorine atom may be linear, branched or cyclic, and preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and particularly preferably 1 to 10 carbon atoms.

In addition, it is preferable that the hydrocarbon group containing a fluorine atom has 25% or more of the hydrogen atoms in the hydrocarbon group fluorinated, more preferably 50% or more of the hydrogen atoms are fluorinated, and particularly preferably 60% or more of the hydrogen atoms are fluorinated because this increases the hydrophobicity of the resist film.

Among these, as Rf ¹⁰¹ , a fluorinated hydrocarbon group having 1 to 6 carbon atoms is more preferable, and a trifluoromethyl group, -CH ₂ -CF ₃ , -CH ₂ -CF ₂ -CF ₃ , -CH(CF ₃ ) ₂ , -CH ₂ -CH ₂ -CF ₃ , -CH ₂ -CH ₂ -CF ₂ -CF ₂ -CF ₂ -CF ₃ are particularly preferable.

(F) The weight average molecular weight (Mw) of the component (based on polystyrene conversion by gel permeation chromatography) is preferably 1,000 to 50,000, more preferably 5,000 to 40,000, and particularly preferably 10,000 to 30,000. When the Mw of the component (F) is equal to or lower than the upper limit of the above-mentioned preferable range, the component has sufficient solubility in a resist solvent for use as a resist, and when it is equal to or higher than the lower limit of the above-mentioned preferable range, the dry etching resistance and the cross-sectional shape of the resist pattern become better, and furthermore, the water repellency of the resist film surface is expressed well.

(F) The dispersion ratio (Mw/Mn) of the component is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and particularly preferably 1.2 to 2.5.

In the resist composition of the present embodiment, component (F) may be used alone or in combination of two or more types.

When the resist composition contains component (F), the content of component (F) is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of component (A).

The resist composition of the present embodiment may additionally contain, as desired, additives that are compatible, for example, additional resins, surfactants, dissolution inhibitors, plasticizers, stabilizers, colorants, anti-halation agents, dyes, etc. for improving the performance of the resist film.

(Method of forming a resist pattern)

The second aspect of the present invention is a method for forming a resist pattern, comprising the steps of (i) forming a resist film on a support using the resist composition related to the first aspect described above, (ii) exposing the resist film, and (iii) developing the resist film after the exposure to form a resist pattern.

As one embodiment of such a resist pattern forming method, for example, a resist pattern forming method performed as follows can be exemplified.

Process (i):

First, the resist composition of the embodiment described above is applied onto a support using a spinner or the like, and a bake (post-apply bake (PAB)) treatment is performed at a temperature of, for example, 80 to 150° C. for 40 to 120 seconds, preferably 60 to 90 seconds, to form a resist film.

Process (ii):

Next, selective exposure is performed on the resist film, for example, using an exposure device such as a KrF exposure device, through a mask (mask pattern) on which a predetermined pattern is formed, and then baking (post-exposure bake (PEB)) treatment is performed, for example, at a temperature of 80 to 150°C for 40 to 120 seconds, preferably 60 to 90 seconds.

Process (iii):

Next, the resist film is developed. In the case of an alkaline developing process, the developing process is performed using an alkaline developer, and in the case of a solvent developing process, a developer containing an organic solvent (organic developer) is used.

After the development process, a rinsing process is preferably performed. In the case of an alkaline development process, a water rinse using pure water is preferable, and in the case of a solvent development process, a rinsing solution containing an organic solvent is preferably used.

In the case of a solvent development process, after the development treatment or rinsing treatment, a treatment may be performed to remove the developer or rinsing solution attached to the pattern using a supercritical fluid.

After the developing treatment or the rinsing treatment, drying is performed. In addition, depending on the case, a baking treatment (post-bake) may be performed after the developing treatment. The baking treatment (post-bake) here is performed, for example, at a temperature of 180°C or higher, preferably 180 to 200°C, for 40 to 120 seconds, preferably 60 to 90 seconds.

In this way, a resist pattern can be formed.

As the support, there is no particular limitation, and a conventionally known one can be used, and examples thereof include a substrate for electronic components, or a substrate having a predetermined wiring pattern formed thereon. More specifically, examples thereof include a silicon wafer, a metal substrate such as copper, chromium, iron, or aluminum, or a glass substrate. Examples of materials for the wiring pattern that can be used include copper, aluminum, nickel, and gold.

In addition, as a support, an inorganic and/or organic film may be formed on a substrate as described above. As an inorganic film, an inorganic antireflection film (inorganic BARC) can be exemplified. As an organic film, an organic antireflection film (organic BARC) or an organic film such as a lower organic film in a multilayer resist method can be exemplified.

Here, the multilayer resist method is a method of forming at least one layer of an organic film (lower organic film) and at least one layer of a resist film (upper resist film) on a substrate, and patterning the lower organic film using the resist pattern formed on the upper resist film as a mask, and it is thought that a high-aspect-ratio pattern can be formed. That is, according to the multilayer resist method, since the necessary thickness can be secured by the lower organic film, the resist film can be thinned, and formation of a high-aspect-ratio fine pattern becomes possible.

Multilayer resist methods are basically divided into a method using a two-layer structure of an upper resist film and a lower organic film (two-layer resist method), and a method using a three-layer or more multilayer structure by forming one or more intermediate layers (such as a metal thin film) between the upper resist film and the lower organic film (three-layer resist method).

The resist pattern forming method of the embodiment is a useful method when forming a thick resist film. Even if the film thickness of the resist film formed in the above step (i) is, for example, 1 to 10 µm, and even within this range, preferably 6 µm or more, further 7 µm or more, and particularly 8 µm or more, a resist pattern can be stably formed in a good shape.

The wavelength used for exposure is not particularly limited, and can be performed using radiation such as ArF excimer laser light, KrF excimer laser light, _F2 excimer laser light, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, or soft X-ray.

The resist composition related to the first aspect described above has high usability as a KrF excimer laser light, an ArF excimer laser light, an EB or EUV light, has even higher usability as a KrF excimer laser light, an ArF excimer laser light, and has particularly high usability as a KrF excimer laser light. The resist pattern forming method related to the second aspect is a particularly preferable method when, in the step (ii), the resist film is irradiated with KrF excimer laser light.

The exposure method of the resist film may be conventional exposure (dry exposure) performed in an inert gas such as air or nitrogen, or liquid immersion lithography.

Immersion exposure is an exposure method in which the space between the resist film and the lowest lens of the exposure device is filled with a solvent (immersion medium) having a refractive index higher than that of air, and exposure (immersion exposure) is performed in that state.

As an immersion medium, a solvent having a refractive index greater than that of air and also smaller than that of the resist film to be exposed is preferable. The refractive index of such a solvent is not particularly limited as long as it is within the above range.

Examples of solvents having a refractive index greater than that of air and smaller than that of the resist film include water, fluorine-based inert liquids, silicone-based solvents, and hydrocarbon-based solvents.

Specific examples of the fluorine-containing inert liquid include liquids whose main components are fluorine compounds such as C ₃ HCl ₂ F ₅ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , and C ₅ H ₃ F ₇ , and the boiling point is preferably 70 to 180 ° C, more preferably 80 to 160 ° C. If the fluorine-containing inert liquid has a boiling point in the above range, the medium used for immersion can be removed by a simple method after exposure is completed, which is preferable.

As a fluorine-containing inert liquid, a perfluoroalkyl compound in which all hydrogen atoms of an alkyl group are replaced with fluorine atoms is particularly preferable. Specific examples of the perfluoroalkyl compound include a perfluoroalkyl ether compound and a perfluoroalkylamine compound.

In addition, specifically, as the perfluoroalkyl ether compound, perfluoro(2-butyl-tetrahydrofuran) (boiling point 102°C) can be exemplified, and as the perfluoroalkylamine compound, perfluorotributylamine (boiling point 174°C) can be exemplified.

As an immersion medium, water is preferably used from the viewpoints of cost, safety, environmental issues, and versatility.

As an alkaline developer used for developing in an alkaline developing process, an example thereof is a 0.1 to 10 mass% tetramethylammonium hydroxide (TMAH) aqueous solution.

The organic solvent contained in the organic developer used for the development treatment in the solvent development process may be any organic solvent capable of dissolving component (A) (component (A) before exposure), and may be appropriately selected from known organic solvents. Specifically, polar solvents such as ketone solvents, ester solvents, alcohol solvents, nitrile solvents, amide solvents, and ether solvents, and hydrocarbon solvents, etc., may be mentioned.

Ketone solvents are organic solvents containing C-C(=O)-C in their structure. Ester solvents are organic solvents containing C-C(=O)-O-C in their structure. Alcohol solvents are organic solvents containing an alcoholic hydroxyl group in their structure. "Alcoholic hydroxyl group" means a hydroxyl group bonded to a carbon atom of an aliphatic hydrocarbon group. Nitrile solvents are organic solvents containing a nitrile group in their structure. Amide solvents are organic solvents containing an amide group in their structure. Ether solvents are organic solvents containing C-O-C in their structure.

Among organic solvents, there are organic solvents that contain multiple functional groups that characterize each of the above solvents in their structures. In such a case, it is considered to correspond to any solvent type that contains the functional groups possessed by the organic solvent. For example, diethylene glycol monomethyl ether is considered to correspond to either alcohol solvents or ether solvents in the above classification.

Hydrocarbon solvents are hydrocarbon solvents that are composed of hydrocarbons that may be halogenated and do not have substituents other than halogen atoms. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, with fluorine atoms being preferred.

Among the organic solvents contained in the organic developer, polar solvents are preferable, and ketone solvents, ester solvents, nitrile solvents, etc. are preferable.

Ketone solvents include, for example, 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone, isophorone, propylene carbonate, γ-butyrolactone, and methyl amyl ketone (2-heptanone). Among these, as the ketone solvent, methyl amyl ketone (2-heptanone) is preferable.

As ester solvents, for example, methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, amyl acetate, isoamyl acetate, ethyl methoxyacetate, ethyl ethoxyacetate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monophenyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monopropyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monophenyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate, 4-methoxybutyl acetate, 3-Methyl-3-methoxybutyl acetate, 3-ethyl-3-methoxybutyl acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, 2-ethoxybutyl acetate, 4-ethoxybutyl acetate, 4-propoxybutyl acetate, 2-methoxypentyl acetate, 3-methoxypentyl acetate, 4-methoxypentyl acetate, 2-methyl-3-methoxypentyl acetate, 3-methyl-3-methoxypentyl acetate, 3-methyl-4-methoxypentyl acetate, 4-methyl-4-methoxypentyl acetate, propylene glycol diacetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, Examples thereof include propyl lactate, ethyl carbonate, propyl carbonate, butyl carbonate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, butyl pyruvate, methyl acetoacetate, ethyl acetoacetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, methyl-3-methoxypropionate, ethyl-3-methoxypropionate, ethyl-3-ethoxypropionate, and propyl-3-methoxypropionate. Among these, as an ester solvent, butyl acetate is preferable.

Examples of nitrile solvents include acetonitrile, propionitrile, valeronitrile, and butyronitrile.

In the organic developer, known additives can be mixed as needed. Examples of the additives include surfactants. The surfactants are not particularly limited, but examples thereof include ionic or nonionic fluorine-based and/or silicone-based surfactants. As the surfactant, a nonionic surfactant is preferable, and a nonionic fluorine-based surfactant or a nonionic silicone-based surfactant is more preferable.

When blending a surfactant, the blending amount is usually 0.001 to 5 mass%, preferably 0.005 to 2 mass%, and more preferably 0.01 to 0.5 mass%, relative to the total amount of the organic developer.

The developing process can be carried out by a known developing method, and examples thereof include a method of immersing a support in a developing solution for a certain period of time (dip method), a method of mounting a developing solution on the surface of a support by surface tension and leaving it there for a certain period of time (paddle method), a method of spraying a developing solution on the surface of a support (spray method), and a method of continuously dispensing a developing solution while scanning a developing solution dispensing nozzle at a certain speed on a support rotating at a certain speed (dynamic dispensing method).

As the organic solvent contained in the rinse solution used for the rinse treatment after the development treatment in the solvent development process, for example, among the organic solvents exemplified as organic solvents used in the above organic developer, an organic solvent which does not dissolve the resist pattern well can be appropriately selected and used. Usually, at least one solvent selected from a hydrocarbon solvent, a ketone solvent, an ester solvent, an alcohol solvent, an amide solvent, and an ether solvent is used. Among these, at least one solvent selected from a hydrocarbon solvent, a ketone solvent, an ester solvent, an alcohol solvent, and an amide solvent is preferable, at least one solvent selected from an alcohol solvent and an ester solvent is more preferable, and an alcohol solvent is particularly preferable.

The alcohol solvent used in the rinse liquid is preferably a monohydric alcohol having 6 to 8 carbon atoms, and the monohydric alcohol may be linear, branched, or cyclic. Specifically, examples thereof include 1-hexanol, 1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, and benzyl alcohol. Among these, 1-hexanol, 2-heptanol, and 2-hexanol are preferable, and 1-hexanol and 2-hexanol are more preferable.

These organic solvents may be used alone or in combination of two or more. In addition, they may be used in combination with organic solvents other than those mentioned above or with water. However, considering the development characteristics, the amount of water in the rinse solution is preferably 30 mass% or less, more preferably 10 mass% or less, still more preferably 5 mass% or less, and particularly preferably 3 mass% or less, with respect to the total amount of the rinse solution.

The rinse solution may contain known additives as needed. Examples of such additives include surfactants. Surfactants include the same surfactants as those described above, and nonionic surfactants are preferred, and nonionic fluorine-based surfactants or nonionic silicone-based surfactants are more preferred.

When blending a surfactant, the blending amount is usually 0.001 to 5 mass%, preferably 0.005 to 2 mass%, and more preferably 0.01 to 0.5 mass%, relative to the total amount of the rinse liquid.

The rinsing treatment (cleaning treatment) using a rinsing solution can be performed by a known rinsing method. Examples of the rinsing treatment method include a method of continuously drawing out the rinsing solution onto a support rotating at a constant speed (rotary application method), a method of immersing the support in the rinsing solution for a constant period of time (dip method), and a method of spraying the rinsing solution onto the surface of the support (spray method).

The resist composition of the present embodiment described above contains a polymer compound (A1) having a structural unit (a10) and a structural unit (a1), and an acid generator (B1) having a cation moiety of a specific structure, and the solid content concentration in the resist composition is 30 mass% or more.

And, in the formation of a resist pattern using a resist composition containing these (A1) components and (B1) components and having a solid content concentration of 30 mass% or more, particularly when forming a thick resist film, the lithography properties are excellent, such as, for example, the uniformity of pattern dimensions can be increased. In addition, the applicability to a support surface is also good, and a resist film having a uniform thickness can be easily formed. In addition, foaming from the resist pattern during high-temperature baking, which has been a problem in the past, is suppressed. In this way, according to the resist composition of the present embodiment, a thick resist pattern can be stably formed with a good shape.

These resist compositions and methods for forming resist patterns are useful, for example, for applications requiring a thick resist film. In addition, these resist compositions and methods for forming resist patterns are useful for applications processing a multi-stage step structure, and by applying the present invention, it is possible to realize high-precision lamination of memory films (three-dimensionalization, production of large-capacity memory).

Example

Hereinafter, the present invention will be described in more detail by examples, but the present invention is not limited to these examples.

＜Preparation of a resist composition＞

(Example 1, Comparative Examples 1 to 4)

Each component shown in Table 1 was mixed and dissolved in a mixed solvent (propylene glycol monomethyl ether/propylene glycol monomethyl ether acetate = 8/2 (mass ratio)) to prepare a resist composition for each example. The solid content concentration in the resist composition for each example is shown in Table 1.

In Table 1, each abbreviation has the following meaning. The value in [ ] is the mixing amount (mass part).

(A)-1: A polymer compound represented by the following chemical formula (A1-1). The weight-average molecular weight (Mw) converted to standard polystyrene as determined by GPC measurement is 10000, and the molecular weight dispersion (Mw/Mn) is 1.8. The copolymer composition ratio (the ratio of each constituent unit in the structural formula (molar ratio)) determined by ^13C -NMR is l/m/n = 60/20/20.

(A)-2: A polymer compound represented by the following chemical formula (A1-2). The weight-average molecular weight (Mw) converted to standard polystyrene as determined by GPC measurement is 20000, and the molecular weight dispersion (Mw/Mn) is 1.8. The copolymer composition ratio (the ratio of each constituent unit in the structural formula (molar ratio)) determined by ^13C -NMR is l/m/n = 60/20/20.

[Chemical formula 53]

(B1)-1: A compound represented by the following chemical formula (B1-1).

(B2)-1: A compound represented by the following chemical formula (B2-1).

(B2)-2: N-(Trifluoromethanesulfonyloxy)bicyclo[2.2.1]hepto-5-ene-2,3-dicarboximide.

[Chemical Formula 54]

(D)-1: Triamylamine.

(E)-1: Phenylphosphonic acid.

＜Formation of the registration pattern＞

Process (i):

On an 8-inch silicon wafer, an organic anti-reflection film composition, “DUV-42P” (trade name, manufactured by Brewer Science Co., Ltd.), was applied using a spinner and dried by baking on a hot plate at 180°C for 60 seconds, thereby forming an organic anti-reflection film with a film thickness of 65 nm.

On the organic antireflection film, each resist composition was applied using a spinner, and dried by prebaking (PAB) at 140° C. for 90 seconds on a hot plate, thereby forming a resist film with a film thickness of 8 μm.

In addition, when the resist composition of Comparative Example 4 was used, a resist film having a film thickness of 8 ㎛ could not be formed, so the subsequent operations were not performed.

Process (ii):

Next, the resist film was selectively irradiated with KrF excimer laser light (248 nm) at the optimal exposure dose (Eop) for each resist composition through a mask pattern (6% halftone) using a KrF exposure device NSR-S205C (manufactured by Nikon; NA (numerical aperture) = 0.68, σ = 0.60).

Afterwards, post-exposure baking (PEB) treatment was performed at 115°C for 90 seconds.

Process (iii):

Next, alkaline development was performed using a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution “NMD-3” (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) as a developing solution at 23°C for 60 seconds.

After that, using pure water, rinse for 30 seconds and dry by shaking.

As a result of the above-described <Formation of a Resist Pattern>, in all examples (Example 1, Comparative Examples 1 to 3), a space-and-line pattern (hereinafter referred to as “SL pattern”) having a space width of 3.75 ㎛ and a pitch width of 7.5 ㎛ was formed in the resist film.

[Evaluation of dimensional uniformity (CDU) within the support surface (Shot)]

For each obtained SL pattern, the SL pattern was observed from above using a scanning electron microscope (SEM, accelerating voltage 300 V, product name: S-9380, manufactured by Hitachi High-Technologies Co., Ltd.), and the space width (nm) in the SL pattern was measured. The standard deviation (σ) calculated from the measurement results was obtained in three batches (3σ), and the dimensional uniformity (CDU) within the support surface (Shot) was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 2 as "CDU".

metewand

◎: 3σ is 15 nm or less.

○: 3σ is greater than 15 nm and less than or equal to 20 nm.

×: 3σ exceeds 20 nm.

The smaller the value of 3σ obtained in this way, the higher the uniformity of the dimension (CD) of the space width formed in the resist film.

[Evaluation of film thickness uniformity within the support surface (Shot)]

In the above [Evaluation of dimensional uniformity (CDU) within the support surface (Shot)], for each of the resist compositions of Example 1, Comparative Example 1 and Comparative Example 3 that gave good results, the film thickness uniformity of the resist film having a film thickness of 8 µm after the prebake (PAB) treatment in the step (i) of the above <Formation of a resist pattern> was evaluated as follows.

The film thickness (Å) of the resist film at 10 points (equally spaced) between both ends of the diameter of a silicon wafer was measured using Nanospec 7001-0066XPW (product name, manufactured by Nanometrics Japan), and the film thickness uniformity within the support surface (Shot) was evaluated according to the evaluation criteria below. The evaluation results are shown in Table 2 as “film thickness uniformity.”

metewand

○: High film thickness uniformity (when the difference in film thickness within a shot is ±25 nm or less).

×: The film thickness uniformity is low (when the difference in film thickness within a shot exceeds ±25 nm).

[Evaluation of the presence or absence of firing]

In the above [Evaluation of film thickness uniformity], for each of the resist compositions of Example 1 and Comparative Example 1 that gave good results, after steps (i), (ii), and (iii) in the above <Formation of resist pattern>, i.e., after brushing and drying, heating was further performed at 180° C. for 60 seconds (post-baking), and the presence or absence of foaming from the resist pattern at that time was visually evaluated. The results are shown in Table 2 as “Presence or absence of foaming.”

From the results shown in Table 2, it can be confirmed that when a resist pattern is formed using the resist composition of Example 1 to which the present invention is applied, the lithography characteristics are excellent, the applicability is also good, and furthermore, foaming from the resist pattern during high-temperature baking is suppressed.

Claims (8)

A resist composition that generates acid upon exposure and whose solubility in a developer changes by the action of the acid,
A polymer compound (A1) having a structural unit (a10) represented by the following general formula (a10-1) and a structural unit (a1) including an acid-decomposable group whose polarity increases by the action of an acid, and an acid generator (B1) represented by the following general formula (b1),
A resist composition having a solid content concentration of 30 mass% or more.

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. Ya ^x1 is a single bond or a divalent linking group. Wa ^x1 is an aromatic hydrocarbon group having a valence of (n _ax1 + 1). n _ax1 is an integer of 1 to 3. R ²⁰¹¹ , R ²⁰²¹ , and R ²⁰³¹ each independently represent an aryl group which may have a substituent. Two or more of R ²⁰¹¹ , R ²⁰²¹ , and R ²⁰³¹ may be bonded to each other to form a ring together with the sulfur atom in the formula. X ^- represents an anion represented by the following general formula (an-1).]

[In the formula, R" ¹⁰¹ is an aliphatic cyclic group which may have a substituent, a group represented by each of the above formulas (r-hr-1) to (r-hr-6), or a chain-shaped alkyl group which may have a substituent. V" ¹⁰¹ is a single bond, an alkylene group having 1 to 4 carbon atoms, or a fluorinated alkylene group having 1 to 4 carbon atoms. R ¹⁰² is a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms. v" is an integer of 0 to 3, q" is an integer of 1 to 20, and n" is 0 or 1. * represents a bond.] In paragraph 1,
A resist composition, wherein ^X in the above general formula (b1) is an anion represented by the following general formula (an-1-1).
In paragraph 1,
The above resist composition comprises a solvent,
A resist composition, wherein the solvent is a mixed solvent comprising propylene glycol monomethyl ether (PGME) and ethyl lactate (EL). In paragraph 1,
At least one of R ²⁰¹¹ , R ²⁰²¹ and R ²⁰³¹ in the above general formula (b1) is an aryl group having a substituent,
A resist composition, wherein the substituent is at least one selected from the group consisting of an alkyl group, a halogen atom, a halogenated alkyl group, a carbonyl group, a cyano group, an amino group, an aryl group, and groups each represented by the following general formulae (ca-r-1) to (ca-r-7).

[In the formula, R' ²⁰¹ is, each independently, a hydrogen atom, a cyclic group which may have a substituent, a chain-shaped alkyl group which may have a substituent, or a chain-shaped alkenyl group which may have a substituent.] In paragraph 1,
A resist composition, wherein the concentration of the polymer compound (A1) in the total solid content of the resist composition is 90 mass% or more. In paragraph 1,
A resist composition wherein the weight average molecular weight of the polymer compound (A1) is 5,000 to 20,000. A method for forming a resist pattern, comprising the steps of: (i) forming a resist film on a support using the resist composition described in any one of claims 1 to 6; (ii) exposing the resist film; and (iii) developing the resist film after the exposure to form a resist pattern. In paragraph 7,
A method for forming a resist pattern, wherein in the above process (ii), KrF excimer laser light is irradiated onto the resist film.