WO2013047528A1 - Photoresist composition and resist pattern forming method - Google Patents

Abstract

The present invention involves a photoresist composition containing (A) a polymer having a structural unit (I) represented by formula (1), and (B) an acid-generating body, wherein the Van der Waals volume of the acid generated from the acid-generating body (B) is not less than 2.1 × 10^-28m³. In formula (1): R¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R² and R³ are, independently, each a hydrogen atom, a fluorine atom, a hydroxy group or a monovalent organic group with one to twenty carbons, or R² and R³ are combined with each other to represent a ring structure with three to twenty carbons constituted in conjunction with a carbon atom to which R² and R³ are bonded; and R⁴ and R⁵ are, independently, each a hydrogen atom or a monovalent organic group with one to twenty carbons, or R⁴ and R⁵ are combined with each other to represent a ring structure with three to twenty carbons constituted in conjunction with a carbon atom to which R⁴ and R⁵ are bonded. n is an integer from one to four.

Description

Photoresist composition and resist pattern forming method

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

The chemically amplified photoresist composition generates an acid in the exposed portion by irradiation with far ultraviolet rays or electron beams typified by KrF excimer laser light (wavelength 248 nm) or ArF excimer laser light (wavelength 193 nm). A difference is caused in the dissolution rate of the exposed portion and the unexposed portion with respect to the developer by a chemical reaction using as a catalyst to form a resist pattern on the substrate.

As a photoresist composition that can be finely processed using an ArF excimer laser as a light source, for example, a composition containing a polymer having an alicyclic hydrocarbon having no absorption in a 193 nm region in a skeleton is known. Contrast is improved. As such a polymer, a polymer containing a structural unit having a spirolactone structure has been proposed (see JP 2002-82441 A and JP 2002-308937 A).

However, with the progress of further miniaturization of resist patterns, the level of performance required for resist films is further increased. Therefore, in conventional photoresist compositions, MEEF performance (a value relating to mask error tolerance) ( Mask Error Enhancement Factor), LWR performance (Line Width Roughness), which is a value representing variation in line width, and the like cannot be sufficiently satisfied.

JP 2002-82441 A JP 2002-308937 A

The present invention has been made based on the above-described circumstances, and an object of the present invention is to provide a photoresist composition excellent in MEEF performance and LWR performance, and a method for forming a resist pattern.

The invention made to solve the above problems is
[A] a polymer having a structural unit (I) represented by the following formula (1) (hereinafter also referred to as “[A] polymer”), and [B] an acid generator,
[B] A photoresist composition in which the van der Waals volume of the acid generated from the acid generator is 2.1 × 10 ⁻²⁸ m ³ or more.

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² and R ³ are each independently a hydrogen atom, a fluorine atom, a hydroxy group or a carbon number. Represents a monovalent organic group having 1 to 20 or a ring structure having 3 to 20 carbon atoms constituted by carbon atoms to which R ² and R ³ are combined and bonded to each other, provided that R ² and R 3 ^It is not the case where both are hydroxy groups ^3. R ⁴ and R ⁵ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, or R ⁴ and R ⁵ are combined with each other. And represents a ring structure having 3 to 20 carbon atoms and a carbon atom to which they are bonded, n is an integer of 1 to 4. When n is 2 or more, a plurality of R ² and R ³ are the same. But it may be different.)

The said photoresist composition is excellent in MEEF performance and LWR performance by containing a [A] polymer and a [B] acid generator. Although it is not necessarily clear why the photoresist composition has the above-described configuration, the [A] polymer has the structural unit (I). B] The acid generated from the acid generator has a certain bulkiness or more, and as a synergistic effect thereof, the diffusion length of the acid can be appropriately shortened.

[B] The acid generated from the acid generator preferably has an alicyclic structure having 6 to 15 carbon atoms. [B] It is considered that the acid generated from the acid generator has the above specific structure, so that the diffusion length of the generated acid can be further optimized. As a result, the photoresist composition is more excellent in MEEF performance and LWR performance.

[B] The acid generator includes a cation and an anion, and the anion is preferably represented by the following formula (3).

(In Formula (3), R ¹⁰ is a monovalent group having an alicyclic structure having 6 to 15 carbon atoms. Y ¹ and Y ² are each independently a single bond, an oxygen atom, or a nitrogen atom. R ¹¹ is a divalent hydrocarbon group having 1 to 20 carbon atoms, and R ¹² is a (q + 1) valent group having 1 to 20 carbon atoms. In addition, when q is 1, R ¹² may be a single bond, and R ^f1 and R ^f2 each independently represent a hydrogen atom, a fluorine atom, or an alkyl having 1 to 30 carbon atoms. Or a fluorinated alkyl group having 1 to 30 carbon atoms, p is an integer of 0 to 2, q is an integer of 1 to 3, and r is an integer of 0 to 5, provided that When there are a plurality of R ¹⁰ , Y ¹ , Y ² , R ¹¹ , R ^f1 and R ^f2 , a plurality of R ¹⁰ , Y ¹ , Y ² , R ¹¹ , R ^f1 and R ^f2 may be the same or different.)

[B] It is considered that the anion of the acid generator has the above specific structure, so that the generated acid becomes bulky and the acid diffusion length can be made more appropriate. As a result, the photoresist composition is further excellent in MEEF performance and LWR performance.

The anion preferably has at least one structure selected from the group consisting of an adamantane structure and a norbornane structure. [B] It is considered that when the anion of the acid generator has the specific structure, the generated acid is further bulky, and the acid diffusion length can be further optimized. As a result, the photoresist composition is further excellent in MEEF performance and LWR performance.

At least one of R ² , R ³ , R ⁴ and R ^{5 in} the above formula (1) is a monovalent organic group having 1 to 20 carbon atoms, and this monovalent organic group is a hetero atom or a halogen atom. It preferably contains at least one atom selected from the group consisting of At least one of R ² , R ³ , R ^4, and R ^{5 is} a monovalent organic group having 1 to 20 carbon atoms, and the monovalent organic group has a hetero atom or a halogen atom, so that [A It is considered that the polarity of the polymer is increased and the diffusion length of the generated acid can be further optimized. As a result, the photoresist composition is further excellent in MEEF performance and LWR performance.

R ⁴ and R ⁵ in the above formula (1) preferably represent a ring structure having 3 to 20 carbon atoms which is constituted together with the carbon atom to which they are bonded together. When the structural unit (I) includes such a spiro ring structure, the [A] polymer has increased rigidity, and as a result, the photoresist composition is further excellent in MEEF performance and LWR performance.

The ring structure preferably has a polar group. When the ring structure has a polar group, the polarity of the [A] polymer is further increased. As a result, the photoresist composition is further excellent in MEEF performance and LWR performance.

[A] The polymer preferably further has a structural unit (II) represented by the following formula (2).

(In the formula (2), R ⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁷ is an alkyl group having 1 to 4 carbon atoms or an alicyclic group having 4 to 20 carbon atoms. R ⁸ and R ⁹ are each independently an alkyl group having 1 to 4 carbon atoms or an alicyclic group having 4 to 20 carbon atoms, or R ⁸ and R ⁹ are combined with each other Represents a divalent alicyclic group constituted with carbon atoms to be bonded.)

Structural unit (II) contains an acid dissociable group in its structure. Therefore, the sensitivity etc. of the said photoresist composition can be improved because a [A] polymer further has such a structural unit (II).

The resist pattern forming method of the present invention comprises:
(1) A step of forming a resist film on a substrate using the photoresist composition;
(2) a step of exposing the resist film by radiation irradiation through a photomask; and (3) a step of developing the exposed resist film.

According to the resist pattern forming method, since the photoresist composition is used, a fine resist pattern having a small LWR can be formed while exhibiting excellent MEEF.

In the present specification, the “van der Waals volume” refers to the volume of the region occupied by the van der Waals sphere based on the van der Waals radius of the atoms constituting the acid. The van der Waals volume is a value calculated by obtaining a stable structure by the PM3 method using WinMOPAC (Fujitsu, Ver. 3.9.0). “Organic group” refers to a group containing at least one carbon atom.

The present invention can provide a photoresist composition excellent in MEEF performance and LWR performance, and a method for forming a resist pattern. Therefore, the photoresist composition can be suitably used in a lithography process that requires further miniaturization.

<Photoresist composition>
The photoresist composition of the present invention contains a [A] polymer and a [B] acid generator. Moreover, the said photoresist composition can contain the [C] acid diffusion control agent and [D] fluorine atom containing polymer which are mentioned later as a suitable component. Furthermore, the said photoresist composition may contain another arbitrary component, unless the effect of this invention is impaired. Hereinafter, each component will be described in detail.

<[A] polymer>
[A] The polymer is a polymer having the structural unit (I). [A] The polymer preferably has the structural unit (II). Furthermore, the [A] polymer may have other structural units other than the structural unit (I) and the structural unit (II) as long as the effects of the present invention are not impaired. In addition, the [A] polymer may have 2 or more types of each structural unit. Hereinafter, each structural unit will be described in detail.

[Structural unit (I)]
The structural unit (I) is a structural unit represented by the above formula (1). In the photoresist composition, the [A] polymer has the structural unit (I) including the specific structure, and the [B] acid generator having the specific structure includes the MEEF performance and the LWR performance. Excellent.

In said formula (1), R < ¹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ² and R ³ are each independently a hydrogen atom, a fluorine atom, a hydroxy group, or a monovalent organic group having 1 to 20 carbon atoms, or R ² and R ³ are combined with each other and bonded to each other. A ring structure having 3 to 20 carbon atoms and a carbon atom is represented. However, there is no case where R ² and R ³ are both hydroxy groups. R ⁴ and R ⁵ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, or are configured together with the carbon atom to which R ⁴ and R ⁵ are combined with each other and bonded to each other. A ring structure having 3 to 20 carbon atoms is represented. n is an integer of 1 to 4. When n is 2 or more, the plurality of R ² and R ³ may be the same or different.

R ¹ is preferably a hydrogen atom or a methyl group.

The monovalent organic group having 1 to 20 carbon atoms represented by R ² to R ⁵ is, for example, selected from the group consisting of a hydrocarbon group having 1 to 20 carbon atoms and a hetero atom and a halogen atom in the hydrocarbon group. And a monovalent group containing at least one kind of atom.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include linear or branched chain hydrocarbon groups, alicyclic groups having 3 to 20 carbon atoms, and aromatic groups having 6 to 20 carbon atoms. Is mentioned.

Examples of the linear or branched chain hydrocarbon group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, and a dodecyl group. It is done.

Examples of the alicyclic group having 3 to 20 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, and a cyclododecyl group.

Examples of the aromatic group having 6 to 20 carbon atoms include a phenyl group, a tolyl group, and a naphthyl group.

Examples of the hetero atom in the monovalent group containing at least one atom selected from the group consisting of the hetero atom and the halogen atom include an oxygen atom, a nitrogen atom, and a sulfur atom.

Examples of the halogen atom include a chlorine atom and a fluorine atom.

Examples of the hydrocarbon group having 1 to 20 carbon atoms containing at least one atom selected from the group consisting of the above hetero atom and halogen atom include a monovalent group containing a divalent hetero atom-containing group, and the above hydrocarbon group. And a group obtained by substituting a hydrogen atom of a group containing a divalent heteroatom-containing group with a monovalent heteroatom-containing group and / or a halogen atom. Examples of the divalent heteroatom-containing group include —CO—, —COO—, —OCO—, —O—, —NR—, —CS—, —S—, —SO—, —SO ₂ — and the like. Can be mentioned. R is a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. Examples of the monovalent heteroatom-containing group include a hydroxy group, a carboxy group, an amino group, and a sulfonamide group.

As the monovalent group containing a hetero atom, for example, when the hetero atom is an oxygen atom, an alkoxy group such as a methoxy group and an ethoxy group; an alkoxyalkyl group such as a methoxymethyl group and a methoxyethyl group; a hydroxymethyl group and a hydroxyethyl group Cycloalkyloxy groups such as cyclopentyloxy group and cyclohexyloxy group; cyclic ether groups such as tetrahydrofuryl group and tetrahydropyranyl group; hydroxycycloalkyl groups such as hydroxycyclopentyl group and hydroxycyclohexyl group, etc. .

Examples of the ring structure having 3 to 20 carbon atoms constituted by combining R ² and R ³ and R ⁴ and R ⁵ with each other include, for example, a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, Monocyclic saturated hydrocarbon structures such as cyclooctane structure, cyclodecane structure, methylcyclohexane structure, ethylcyclohexane structure;
Monocyclic unsaturated hydrocarbon structures such as cyclobutene structure, cyclopentene structure, cyclohexene structure, cycloheptene structure, cyclooctene structure, cyclodecene structure, cyclopentadiene structure, cyclohexadiene structure, cyclooctadiene structure, cyclodecadiene structure;
Bicyclo [2.2.1] heptane structure, bicyclo [2.2.2] octane structure, tricyclo [5.2.1.0 ^2,6 ] decane structure, tricyclo [3.3.1.1 ^3,7 ] Decane structure, tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] polycyclic saturated hydrocarbon structures such as dodecane structure and adamantane structure;
Bicyclo [2.2.1] heptene structure, bicyclo [2.2.2] octene structure, tricyclo [5.2.1.0 ^2,6 ] decene structure, tricyclo [3.3.1.1 ^3,7 ] Decene structure, tetracyclo [6.2.1.1 ^3,6 . And a polycyclic unsaturated hydrocarbon structure such as 0 ^2,7 ] dodecene structure. In addition, a monovalent group containing the above-mentioned divalent heteroatom-containing group between carbon-carbons of these structures, a hydrogen atom contained in the above-described hydrocarbon group and a group containing a divalent heteroatom-containing group can be converted to a monovalent heterogeneous group. Examples include those containing an atom-containing group and / or a group substituted with a halogen atom.

Examples of the structure containing a —CO— group between carbon and carbon in the ring structure include a cyclic ketone structure having 3 to 8 carbon atoms.

Examples of the structure containing a —COO— group between carbon and carbon in the ring structure include a lactone structure having 3 to 8 carbon atoms.

Examples of the structure containing an —O— group between carbon and carbon in the ring structure include a cyclic ether structure having 3 to 8 carbon atoms.

Examples of the structure containing an —NR— group between carbon and carbon in the ring structure include a cyclic amine structure having 3 to 8 carbon atoms.

Examples of the structure containing an —S— group between carbon and carbon in the ring structure include a cyclic thioether structure having 3 to 8 carbon atoms.

Examples of the structure containing an —SO— group between carbon and carbon in the ring structure include a cyclic sulfoxide structure having 3 to 8 carbon atoms.

Examples of the structure containing a —SO ₂ — group between carbon and carbon in the ring structure include a cyclic sulfonyl structure having 3 to 8 carbon atoms.

In addition, as the ring structure composed of the carbon atoms to which R ² and R ³ , R ⁴ and R ⁵ are combined with each other and bonded thereto, those having a 5-membered or 6-membered ring structure are easy to synthesize. From the point of view, it is preferable.

R ² , R ³ , R ⁴ and R ⁵ are each a hydrogen atom, a linear or branched chain hydrocarbon group having 1 to 20 carbon atoms including a hetero atom, or R ² and R ³ or R ⁴ and R ⁵ are preferably combined with each other to represent a ring structure of 3 to 20 carbon atoms formed with the carbon atom to which they are bonded, and a hydrogen atom or R ⁴ and R ⁵ are combined with each other It is more preferable that they represent a ring structure having 3 to 20 carbon atoms constituted with carbon atoms to which they are bonded, and R ⁴ and R ⁵ are combined with each other and have 5 or 6 carbon atoms constituted with carbon atoms to which they are bonded. More preferably, it represents a ring structure. By forming such a ring structure, the rigidity of the [A] polymer is increased, and as a result, the photoresist composition is more excellent in MEEF performance and LWR performance.

At least one of R ² , R ³ , R ⁴ and R ⁵ is a monovalent organic group having 1 to 20 carbon atoms, and the monovalent organic group is selected from the group consisting of a hetero atom and a halogen atom. Preferably, it contains at least one kind of atom. Since at least one of R ² , R ³ , R ⁴ and R ⁵ has a hetero atom and a halogen atom, the polarity of the [A] polymer is increased, and as a result, the photoresist composition has a MEEF performance and Excellent LWR performance.

The ring structure preferably has a polar group. When the ring structure has a polar group, the polarity of the [A] polymer is further increased. As a result, the photoresist composition is further excellent in MEEF performance and LWR performance. Examples of the polar group include monovalent groups such as a hydroxy group, a carboxy group, an amino group, a thiol group, and a sulfonamide group, and divalent groups such as an imino group and a sulfonimino group. Of these, the polar group is preferably a monovalent group, and more preferably a hydroxy group.

N is preferably 1 or 2, and more preferably 1.

Examples of the monomer giving the structural unit (I) include monomers (1-1) to (1-25) represented by the following formulas.

Of the above monomers, monomers (1-1), (1-17) and (1-20) are preferred, and monomer (1-1) and monomer (1-17) are more preferred. Monomer (1-17) is most preferred.

[A] The content of the structural unit (I) in the polymer is preferably 5 mol% to 60 mol%, more preferably 5 mol% to 50 mol%, based on all structural units constituting the [A] polymer. preferable. By making the content rate of structural unit (I) into the said specific range, the resist pattern excellent in MEEF performance and LWR performance can be formed.

[Structural unit (II)]
[A] The polymer preferably further has a structural unit (II) represented by the above formula (2). [A] When the polymer further has the structural unit (II), the photoresist composition can improve sensitivity and the like.

In the formula (2), R ⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁷ is an alkyl group having 1 to 4 carbon atoms or an alicyclic group having 4 to 20 carbon atoms. R ⁸ and R ⁹ are each independently an alkyl group having 1 to 4 carbon atoms or an alicyclic group having 4 to 20 carbon atoms, or carbons to which R ⁸ and R ⁹ are combined with each other and bonded to each other. Represents a divalent alicyclic group configured with atoms.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ⁷ to R ⁹ include a methyl group, an ethyl group, and a propyl group.

Examples of the alicyclic group having 4 to 20 carbon atoms represented by R ⁷ to R ⁹ include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, and an adamantyl group.

Examples of the divalent alicyclic group constituted by combining R ⁸ and R ⁹ with each other include a cyclopentanediyl group, a norbornanediyl group, an adamantanediyl group, and the like.

Examples of the monomer that gives structural unit (II) include monomers (2-1) to (2-11) represented by the following formulas.

Among the above monomers, monomers (2-2), (2-3), (2-8), (2-9), (2-10) and (2-11) are represented by [A] This is preferable in that the solubility of the polymer in the exposed portion in the developing solution can be increased and the development contrast can be further increased.

[A] The content ratio of the structural unit (II) in the polymer is preferably 10 mol% to 80 mol%, more preferably 15 mol% to 75 mol% with respect to all the structural units constituting the [A] polymer. preferable. By making the content rate of structural unit (II) into the said specific range, the said photoresist composition can further improve a sensitivity etc.

[Structural unit (III)]
[A] The polymer further comprises a structural unit (III) which is a structural unit other than the structural unit (I) and includes at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure. It is preferable to have. [A] When the polymer further includes the structural unit (III), adhesion of the resist film to the substrate can be enhanced.

Examples of the monomer that gives structural unit (III) include monomers (III-1) to (III-25) represented by the following formulas.

Among the above monomers, monomers having a norbornane skeleton are preferable from the viewpoint of etching resistance. Among these, the monomer (III-1) is particularly preferable.

[A] The content of the structural unit (III) in the polymer is preferably 10 mol% to 65 mol%, more preferably 15 mol% to 60 mol% with respect to all the structural units constituting the [A] polymer. preferable. By adjusting the content ratio of the structural unit (III) to the specific range, the adhesion of the resist film to the substrate can be enhanced.

The [A] polymer may have a plurality of other structural units other than the structural unit (I), the structural unit (II) and the structural unit (III) as long as the effects of the present invention are not impaired. .

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized according to a conventional method such as radical polymerization. Examples of the synthesis method include a method in which a solution containing a monomer and a radical initiator is dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction; a solution containing the monomer and a radical initiator A solution containing each of the monomers separately added to a reaction solvent or a solution containing a monomer to cause a polymerization reaction; a plurality of types of solutions containing each monomer; and a solution containing a radical initiator And a method of dropping them into a reaction solvent or a monomer-containing solution to cause a polymerization reaction.

The reaction temperature in the polymerization is appropriately determined depending on the type of radical initiator, but is usually 30 ° C. to 180 ° C., preferably 40 ° C. to 160 ° C., and more preferably 50 ° C. to 140 ° C. The dropping time varies depending on the reaction temperature, the type of radical initiator, the monomer to be reacted, etc., but is usually 30 minutes to 8 hours, preferably 45 minutes to 6 hours, and more preferably 1 hour to 5 hours. The total reaction time including the dropping time is usually 30 minutes to 8 hours, preferably 45 minutes to 7 hours, and more preferably 1 hour to 6 hours.

Examples of the radical initiator include 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis ( 2-cyclopropylpropionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobisisobutyrate (MAIB) and the like. These radical initiators can be used in combination of two or more.

The solvent used for the polymerization is not limited as long as it is a solvent other than a solvent that inhibits polymerization of each monomer and can dissolve the monomer. Examples of the solvent include alcohol solvents, ketone solvents, amide solvents, ester solvents, lactone solvents, nitrile solvents, and the like. Two or more of these solvents can be used in combination.

The polymer obtained by the polymerization reaction can be recovered by a reprecipitation method. As the reprecipitation solvent, an alcohol solvent or the like can be used.

[A] In the polymerization reaction for synthesizing the polymer, a molecular weight modifier can be used to adjust the molecular weight. Examples of the molecular weight modifier include halogenated hydrocarbons such as chloroform and carbon tetrabromide; mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, thioglycolic acid; dimethyl Xanthogens such as xanthogen sulfide and diisopropylxanthogen disulfide; terpinolene, α-methylstyrene dimer and the like.

[A] The polystyrene-equivalent weight average molecular weight (Mw) of the polymer by gel permeation chromatography (GPC) is preferably, for example, 1,000 to 20,000, and more preferably 2,000 to 10,000. [A] By making Mw of a polymer into the above-mentioned specific range, the sensitivity, LWR performance, etc. of the photoresist composition are further improved.

[A] The ratio (Mw / Mn) of Mw to polystyrene-reduced number average molecular weight (Mn) by GPC of the [A] polymer is usually from 1 to 5, preferably from 1 to 3, and more preferably from 1 to 2. By setting Mw / Mn in the specific range, the photoresist composition is excellent in sensitivity, lithography performance such as LWR performance, and etching resistance. In addition, Mw and Mn of the polymer in this specification were measured by GPC under the following conditions.

Column: 2 G2000HXL, 1 G3000HXL, and 1 G4000HXL (Tosoh)
Mobile phase: Tetrahydrofuran Column temperature: 40 ° C
Flow rate: 1.0 mL / min Sample concentration: 1.0 mass%
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

<[B] Acid generator>
The photoresist composition contains a [B] acid generator. [B] The acid generator is a compound or polymer that generates an acid upon exposure, and has a van der Waals volume of the generated acid of 2.1 × 10 ⁻²⁸ m ³ or more. In addition, when the polymer [A] further has the structural unit (II), the acid-dissociable group present in the structural unit (II) is dissociated to generate a carboxy group. As a result, the polarity of the [A] polymer increases and the [A] polymer in the exposed area becomes soluble in the developer.

As the form of inclusion of the [B] acid generator in the photoresist composition, the form of a compound as described later (hereinafter also referred to as “[B] acid generator” as appropriate) is incorporated as part of the polymer. Either of these forms may be used.

The lower limit of the van der Waals volume of the acid generated by the exposure is preferably 2.2 × 10 ⁻²⁸ m ^3, more preferably 2.4 × 10 ⁻²⁸ m ³ , and 2.7 × 10 ⁻²⁸ m ^3. Is more preferable. On the other hand, the upper limit is preferably ¹⁰ × 10 -28 ^{m 3,} more preferably 7 × ¹⁰ -28 ^{m 3,} more preferably 4.0 × ¹⁰ -28 ^{m 3.} By making the van der Waals volume of the acid generated by exposure within the above range, the diffusion length of the acid generated by exposure can be made more appropriate, and as a result, the MEEF performance and LWR performance of the photoresist composition are further improved. .

[B] The acid generated from the acid generator preferably has an alicyclic structure having 6 to 15 carbon atoms. [B] It is considered that the acid generated from the acid generator has the above specific structure, whereby the diffusion length of the acid generated by exposure can be optimized. As a result, the photoresist composition is more excellent in MEEF performance and LWR performance.

Examples of the alicyclic structure having 6 to 15 carbon atoms include a monocyclic alicyclic structure such as a cyclohexane structure, a cycloheptane structure, a cyclooctane structure, a cyclononane structure, a cyclodecane structure, and a cyclododecane structure; a norbornane structure, an adamantane structure, Examples thereof include polycyclic alicyclic structures such as a cyclodecane structure and a tetracyclododecane structure. Among these, a cyclohexane structure, a norbornane structure, and an adamantane structure are preferable, and a norbornane structure and an adamantane structure are more preferable.

[B] The acid generator includes a cation and an anion, and the anion is preferably represented by the above formula (3). [B] Since the anion of the acid generator has the specific structure described above, it is considered that the acid generated by exposure becomes more bulky and the acid diffusion length can be made more appropriate. As a result, the photoresist composition is further excellent in MEEF performance and LWR performance.

In the above formula (3), R ¹⁰ is a monovalent group having an alicyclic structure having 6 to 15 carbon atoms. Y ¹ and Y ² are each independently a divalent linking group containing a single bond, an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom. R ¹¹ is a divalent hydrocarbon group having 1 to 20 carbon atoms. R ¹² is a (q + 1) -valent hydrocarbon group having 1 to 20 carbon atoms. When q is 1, R ¹² may be a single bond. R ^f1 and R ^f2 each independently represent a hydrogen atom, a fluorine atom, an alkyl group having 1 to 30 carbon atoms, or a fluorinated alkyl group having 1 to 30 carbon atoms. p is an integer of 0-2. q is an integer of 1 to 3. r is an integer of 0 to 5. ^{However, R 10, Y 1, Y} 2, R 11, when ^{R f1} and ^{R f2} is plural respective plurality of ^{R 10, Y 1, Y 2} , R 11, R f1 and ^{R f2} are different from each identical It may be.

Examples of the monovalent group having an alicyclic structure having 6 to 15 carbon atoms represented by R ¹⁰ include a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cycloundecyl group, and a cyclododecyl group. A group having a monocyclic alicyclic structure such as a group, cyclotridecyl group, cyclotetradecyl group, cyclopentadecyl group, 7-oxanorbornyl group, 7-azanorbornyl group, cyclohexane lactonyl group;
Polycyclic rings such as norbornyl group, adamantyl group, tricyclodecyl group, tetracyclododecyl group, norbornane lactonyl group, 5-oxo-4-oxatricyclo [4.3.1.1 ^3,8 ] undecan-yl group And a group having an alicyclic structure.

Of these, a group having a polycyclic alicyclic structure is preferable, a norbornyl group, an adamantyl group, and a norbornane lactonyl group are more preferable, and an adamantyl group and a norbornane lactonyl group are more preferable.

Examples of the divalent linking group containing an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom represented by Y ¹ and Y ² include, for example, a carbonyl group, an ester group, an ether group, a carbonate group, an imino group, an amide group, Examples thereof include a carbamate group, a sulfide group, a thiocarbonyl group, a thioester group, a thiocarbonate group, a thioamide group, and a thiocarbamate group. Among these, a carbonyl group, an ester group, an ether group, and a carbonate group are preferable, a carbonyl group and an ester group are more preferable, and an ester group is more preferable.

Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R ¹¹ include, for example, a divalent chain hydrocarbon group having 1 to 20 carbon atoms and a divalent alicyclic group having 3 to 20 carbon atoms. Examples thereof include hydrocarbon groups and divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

Examples of the divalent chain hydrocarbon group having 1 to 20 carbon atoms include a methanediyl group, an ethanediyl group, a propanediyl group, and a butanediyl group.

Examples of the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl group and the like.

Examples of the divalent aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenylene group, a benzylene group, a phenethylene group, a phenylenepropylene group, a naphthylene group, and a naphthylene methylene group.

Examples of the (q + 1) -valent hydrocarbon group having 1 to 20 carbon atoms represented by R ¹² above include further removing (q-1) hydrogen atoms from the divalent hydrocarbon group exemplified as R ¹¹ above. And the like. q is preferably 1 or 2, and more preferably 1. When q is 1, R ¹² is preferably a single bond or an alkanediyl group having 1 to 10 carbon atoms, more preferably a single bond or an alkanediyl group having 1 to 4 carbon atoms, a single bond, a methanediyl group, 2-ethanediyl group, 1,3-propanediyl group and 1,4-butanediyl group are more preferable.

Examples of the alkyl group having 1 to 30 carbon atoms represented by R ^f1 and R ^f2 include, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec- Examples thereof include a propyl group, a t-propyl group, an n-hexyl group, and an n-decyl group.

Examples of the fluorinated alkyl group having 1 to 30 carbon atoms represented by R ^f1 and R ^f2 include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a fluoroethyl group, a difluoroethyl group, a trifluoroethyl group, Examples thereof include a perfluoroethyl group, a perfluoro-n-propyl group, a hexafluoro-i-propyl group, a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group, a perfluorooctyl group, and a perfluorodecyl group.

p is preferably 0 or 1. r is preferably an integer of 0 to 2, more preferably 1 or 2, and still more preferably 1. Examples of the group represented by — (CR ^f1 R ^f2 ) —CF ₂ — include 1,1,2,2-tetrafluoroethanediyl group, 1,1,2-trifluoroethanediyl group, 1,1-difluoro A -2,2-di (trifluoromethyl) ethanediyl group is preferred.

Examples of the anion represented by the above formula (3) include anions represented by the following formulas (3-1) to (3-9).

Of these anions, (3-1), (3-5) and (3-8) are preferred, and (3-5) is more preferred.

[B] The cation contained in the acid generator is preferably a cation represented by the following formula (B-1).

In the above formula (B-1), R ¹³ represents a fluorine atom, a hydroxy group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 2 to 11 carbon atoms, or 1 carbon atom. ~ 10 alkylsulfonyl groups. j is an integer of 0 to 7. When j is 2 or more, the plurality of R ¹³ may be the same or different. R ¹⁴ and R ¹⁵ each independently represents an optionally substituted alkyl group having 1 to 10 carbon atoms or an aromatic hydrocarbon group. However, R ¹⁴ and R ¹⁵ may be bonded to each other to form a ring structure having 2 to 10 carbon atoms together with the sulfur atom to which they are bonded. k is an integer of 0-2.

As the cation represented by the above formula (B-1), cations represented by the following formulas (3-a) to (3-g) are preferable.

Of the above cations, cations (3-a) and (3-e) are more preferred.

These [B] acid generators can be used in combination of two or more. [B] The content when the acid generator is an acid generator is usually 0.1 parts by mass with respect to 100 parts by mass of the polymer [A] from the viewpoint of ensuring sensitivity and developability as a resist. The content is 20 parts by mass or less and preferably 0.5 parts by mass or more and 15 parts by mass or less. [B] When the content of the acid generator is less than 0.1 parts by mass, the sensitivity and developability of the photoresist composition tend to decrease. On the other hand, when the content of the [B] acid generator exceeds 20 parts by mass, the transparency to radiation is lowered, and it may be difficult to obtain a desired resist pattern.

<[C] acid diffusion controller>
The photoresist composition preferably contains a [C] acid diffusion controller. [C] The acid diffusion controller controls the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator upon exposure, and has the effect of suppressing undesirable chemical reactions in the non-exposed areas. When the photoresist composition further contains a [C] acid diffusion controller, a resist pattern that is more excellent in pattern developability, LWR performance, and MEEF performance can be formed.

[C] Examples of the acid diffusion controller include amine compounds, amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

Examples of the amine compound include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines or derivatives thereof; ethylenediamine, N, N, N ′, N′— Tetramethylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylamine, 2,2-bis ( 4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4- Aminophenyl) -2- (4-hydroxyphenyl) propane 1,4-bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, bis (2-dimethylamino) Ethyl) ether, bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxalinol, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ) Ethylenediamine, N, N, N ′, N ″ N ″ -pentamethyldiethylenetriamine and the like.

Examples of the amide group-containing compound include Nt-butoxycarbonyldi-n-octylamine, Nt-amyloxycarbonyldi-n-octylamine, Nt-butoxycarbonyldi-n-nonylamine, N- t-amyloxycarbonyldi-n-nonylamine, Nt-butoxycarbonyldi-n-decylamine, Nt-amyloxycarbonyldi-n-decylamine, Nt-butoxycarbonyldicyclohexylamine, Nt-amino Roxycarbonyldicyclohexylamine, Nt-butoxycarbonyl-1-adamantylamine, Nt-amyloxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-2-adamantylamine, Nt-amyloxycarbonyl- 2-adamantylamine, Nt-butoxy Carbonyl-N-methyl-1-adamantylamine, Nt-amyloxycarbonyl-N-methyl-1-adamantylamine, (S)-(−)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, (S)-(−)-1- (t-amyloxycarbonyl) -2-pyrrolidinemethanol, (R)-(+)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, (R)-( +)-1- (t-amyloxycarbonyl) -2-pyrrolidinemethanol, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine, Nt-butoxycarbonylpyrrolidine Nt-amyloxycarbonylpyrrolidine, N, N′-di-t-butoxycarbonylpiperazine, N, N′-di- -Amyloxycarbonylpiperazine, N, N-di-t-butoxycarbonyl-1-adamantylamine, N, N-di-t-amyloxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-4,4 ' -Diaminodiphenylmethane, Nt-amyloxycarbonyl-4,4'-diaminodiphenylmethane, N, N'-di-t-butoxycarbonylhexamethylenediamine, N, N'-di-t-amyloxycarbonylhexamethylenediamine N, N, N ′, N′-tetra-t-butoxycarbonylhexamethylenediamine, N, N, N ′, N′-tetra-t-amyloxycarbonylhexamethylenediamine, N, N′-di-t -Butoxycarbonyl-1,7-diaminoheptane, N, N'-di-t-amyloxycarbonyl-1, 7-diaminoheptane, N, N′-di-t-butoxycarbonyl-1,8-diaminooctane, N, N′-di-t-amyloxycarbonyl-1,8-diaminooctane, N, N′-di -T-butoxycarbonyl-1,9-diaminononane, N, N'-di-t-amyloxycarbonyl-1,9-diaminononane, N, N'-di-t-butoxycarbonyl-1,10-diaminodecane, N, N′-di-t-amyloxycarbonyl-1,10-diaminodecane, N, N′-di-t-butoxycarbonyl-1,12-diaminododecane, N, N′-di-t-amyloxy Carbonyl-1,12-diaminododecane, N, N′-di-t-butoxycarbonyl-4,4′-diaminodiphenylmethane, N, N′-di-t-amyloxycarbonyl-4,4′- Aminodiphenylmethane, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonylbenzimidazole, Nt-amyloxycarbonyl-2-methylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole, N- and Nt-butoxycarbonyl group-containing amino compounds such as t-amyloxycarbonyl-2-phenylbenzimidazole.

Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tri-n-butylthiourea. Etc.

Examples of the nitrogen-containing heterocyclic compound include imidazoles such as 2-phenylimidazole; pyridines; piperazines and the like.

Furthermore, as the [C] acid diffusion control agent, an onium salt compound that decomposes by exposure and loses basicity as acid diffusion controllability can be used. Examples of such an onium salt compound include a sulfonium salt compound represented by the following formula (4-1), an iodonium salt compound represented by the formula (4-2), and the like.

In the above formulas (4-1) and (4-2), R ¹⁶ to R ²⁰ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, or a halogen atom. Anb ⁻ is OH ⁻ , R ²¹ —COO ⁻ , R ²¹ —SO ₃ ⁻ , or an anion represented by the following formula (5). R ²¹ is each independently an alkyl group, an aryl group, or an alkanol group.

Examples of the sulfonium salt compound and the iodonium salt compound include triphenylsulfonium hydroxide, triphenylsulfonium acetate, triphenylsulfonium salicylate, diphenyl-4-hydroxyphenylsulfonium hydroxide, diphenyl-4-hydroxyphenylsulfonium acetate, and diphenyl. -4-hydroxyphenylsulfonium salicylate, bis (4-t-butylphenyl) iodonium hydroxide, bis (4-t-butylphenyl) iodonium acetate, bis (4-t-butylphenyl) iodonium hydroxide, bis ( 4-tert-butylphenyl) iodonium acetate, bis (4-tert-butylphenyl) iodonium salicylate, 4-tert-butyl Ruphenyl-4-hydroxyphenyliodonium hydroxide, 4-t-butylphenyl-4-hydroxyphenyliodonium acetate, 4-t-butylphenyl-4-hydroxyphenyliodonium salicylate, bis (4-t-butylphenyl) iodonium Examples thereof include 10-camphor sulfonate, diphenyliodonium 10-camphor sulfonate, triphenylsulfonium 10-camphor sulfonate, 4-t-butoxyphenyl diphenylsulfonium 10-camphor sulfonate, and the like.

Of these sulfonium salt compounds and iodonium salt compounds, triphenylsulfonium salicylate and triphenylsulfonium 10-camphorsulfonate are preferred.

[C] Two or more kinds of acid diffusion control agents may be used in combination. [C] The content of the acid diffusion controller is preferably 0.1 parts by mass or more and 10 parts by mass or less, and more preferably 0.1 parts by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the polymer [A]. preferable. [C] By making content of an acid diffusion control agent into the above-mentioned specific range, pattern developability, LWR performance, and MEEF performance improve more.

<[D] Fluorine atom-containing polymer>
[D] The fluorine atom-containing polymer is a polymer containing a fluorine atom, and is a polymer having a higher fluorine atom content ratio than the [A] polymer. The photoresist composition contains the [D] fluorine atom-containing polymer, so that the hydrophobicity of the resist film is further improved. When immersion exposure is performed, the acid generator and the acid diffusion control in the resist film are controlled. The elution of the agent and the like into the immersion medium can be suppressed.

[D] Examples of the fluorine atom-containing polymer include a structure in which a fluorinated alkyl group is bonded to the main chain; a structure in which a fluorinated alkyl group is bonded to the side chain; and a fluorinated alkyl group in the main chain and the side chain. Examples include a bonded structure.

Monomers that give a structure in which a fluorinated alkyl group is bonded to the main chain include, for example, α-trifluoromethyl acrylate compounds, β-trifluoromethyl acrylate compounds, α, β-trifluoromethyl acrylate compounds, one or more types Examples thereof include compounds in which the hydrogen at the vinyl moiety is substituted with a fluorinated alkyl group such as a trifluoromethyl group.

As a monomer that gives a structure in which a fluorinated alkyl group is bonded to a side chain, for example, a compound in which a side chain of an alicyclic olefin compound such as norbornene has a fluorinated alkyl group, a side chain of (meth) acrylic acid is fluorine. A compound having a fluorinated alkyl group, a compound in which a side chain of one or more olefins (site not containing a double bond) has a fluorinated alkyl group, and the like.

Monomers that give a structure in which a fluorinated alkyl group is bonded to the main chain and side chain include, for example, α-trifluoromethylacrylic acid, β-trifluoromethylacrylic acid, α, β-trifluoromethylacrylic acid, etc. And a compound having a fluorinated alkyl group bonded to the main chain and side chain of a compound having a vinyl group as the main chain structure.

[D] The fluorine atom-containing polymer has a structural unit (IV) represented by the following formula (6), a structural unit (V) represented by the following formula (7), and a structure represented by the following formula (8). It is preferable to have at least one structural unit selected from the group consisting of units (VI). [D] The fluorine atom-containing polymer may have other structural units other than the structural unit (IV), the structural unit (V), and the structural unit (VI). In addition, the [D] fluorine atom containing polymer may have 2 or more types of each structural unit. Hereinafter, each structural unit will be described in detail.

[Structural unit (IV)]
The structural unit (IV) is a structural unit represented by the following formula (6).

In the above formula (6), R ²² is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ²³ is a linear or branched alkyl group having 1 to 6 carbon atoms having a fluorine atom or a monovalent alicyclic group having 4 to 20 carbon atoms having a fluorine atom. However, one part or all part of the hydrogen atom which the said alkyl group and alicyclic group have may be substituted.

Among the linear or branched alkyl group having 1 to 6 carbon atoms having a fluorine atom represented by R ^23, a linear or branched alkyl group having 1 to 6 carbon atoms, such as methyl , Ethyl group, propyl group, butyl group and the like.

Among the monovalent alicyclic group having 4 to 20 carbon atoms having a fluorine atom represented by R ²³ , examples of the monovalent alicyclic group having 4 to 20 carbon atoms include a cyclopentyl group and a cyclopentylpropyl group. Cyclohexyl group, cyclohexylmethyl group, cycloheptyl group, cyclooctyl group, cyclooctylmethyl group and the like.

Examples of the monomer that gives the structural unit (IV) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, perfluoroethyl (meth) acrylate, perfluoro n-propyl ( (Meth) acrylate, perfluoro i-propyl (meth) acrylate, perfluoro n-butyl (meth) acrylate, perfluoro i-butyl (meth) acrylate, perfluoro t-butyl (meth) acrylate, perfluorocyclohexyl (meth) Acrylate, 2- (1,1,1,3,3,3-hexafluoro) propyl (meth) acrylate, 1- (2,2,3,3,4,4,5,5-octafluoro) pentyl ( (Meth) acrylate, 1- (2,2,3,3,4,4,5,5-octafluoro) he Sil (meth) acrylate, perfluorocyclohexylmethyl (meth) acrylate, 1- (2,2,3,3,3-pentafluoro) propyl (meth) acrylate, 1- (2,2,3,3,4, 4,4-Heptafluoro) penta (meth) acrylate, 1- (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10- Heptadecafluoro) decyl (meth) acrylate, 1- (5-trifluoromethyl-3,3,4,4,5,6,6,6-octafluoro) hexyl (meth) acrylate and the like. Of these, 2,2,2-trifluoroethyl (meth) acrylate is preferred.

[D] The content ratio of the structural unit (IV) in the fluorine atom-containing polymer is preferably 5 mol% to 50 mol% with respect to the total structural units constituting the [D] fluorine atom containing polymer, and preferably 5 mol%. More preferred is ˜40 mol%.

[Structural unit (V)]
The structural unit (V) is a structural unit represented by the following formula (7).

In the above formula (7), R ²⁴ is a hydrogen atom, a methyl group or a trifluoromethyl group. m is an integer of 1 to 3. R ²⁵ is a (m + 1) -valent linking group. X is a divalent linking group having a fluorine atom. R ²⁶ represents a hydrogen atom or a monovalent organic group. However, when m is 2 or 3, the plurality of X and R ²⁶ may be the same or different.

Examples of the (m + 1) -valent linking group represented by R ²⁶ include linear or branched hydrocarbon groups having 1 to 30 carbon atoms, alicyclic groups having 3 to 30 carbon atoms, and 6 to 6 carbon atoms. 30 aromatic groups, or a group in which these groups are combined with one or more groups selected from the group consisting of an oxygen atom, a sulfur atom, an ether group, an ester group, a carbonyl group, an imino group, and an amide group. It is done. The (m + 1) -valent linking group may have a substituent.

Examples of the linear or branched hydrocarbon group having 1 to 30 carbon atoms include hydrocarbon groups such as methane, ethane, propane, butane, pentane, hexane, heptane, decane, icosane and triacontane (m + 1). And a group excluding individual hydrogen atoms.

Examples of the alicyclic group having 3 to 30 carbon atoms include monocyclic saturated hydrocarbons such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, methylcyclohexane, and ethylcyclohexane;
Monocyclic unsaturated hydrocarbons such as cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, cyclopentadiene, cyclohexadiene, cyclooctadiene, cyclodecadiene;
Bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane, tricyclo [5.2.1.0 ^2,6 ] decane, tricyclo [3.3.1.1 ^3,7 ] decane, Tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] polycyclic saturated hydrocarbons such as dodecane and adamantane;
Bicyclo [2.2.1] heptene, bicyclo [2.2.2] octene, tricyclo [5.2.1.0 ^2,6 ] decene, tricyclo [3.3.1.1 ^3,7 ] decene, Tetracyclo [6.2.1.1 ^3,6 . And a group obtained by removing (m + 1) hydrogen atoms from a polycyclic hydrocarbon such as 0 ^2,7 ] dodecene.

Examples of the aromatic group having 6 to 30 carbon atoms include (m + 1) aromatic hydrocarbons such as benzene, naphthalene, phenanthrene, anthracene, tetracene, pentacene, pyrene, picene, toluene, xylene, ethylbenzene, mesitylene, cumene and the like. And a group in which a hydrogen atom is removed.

Examples of the divalent linking group having a fluorine atom represented by X include, for example, a divalent linear hydrocarbon group having 1 to 20 carbon atoms having a fluorine atom, and a carbon number having 1 fluorine atom having a carbonyl group. And a divalent linear hydrocarbon group of ˜20. Examples of the divalent linear hydrocarbon group having 1 to 20 carbon atoms having a fluorine atom include groups represented by the following formulas (X-1) to (X-7).

X is preferably a group represented by the above formula (X-7).

Examples of the monovalent organic group represented by R ²⁶ include linear or branched hydrocarbon groups having 1 to 30 carbon atoms, alicyclic groups having 3 to 30 carbon atoms, and 6 to 30 carbon atoms. Examples thereof include an aromatic group, or a group obtained by combining these groups with one or more groups selected from the group consisting of an oxygen atom, a sulfur atom, an ether group, an ester group, a carbonyl group, an imino group, and an amide group.

Examples of monomers that give structural unit (V) include (meth) acrylic acid 2- (1-ethoxycarbonyl-1,1-difluoro) butyl ester, (meth) acrylic acid (1,1,1-trifluoro). -2-trifluoromethyl-2-hydroxy-3-propyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-butyl) ester, (meth ) Acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-5-pentyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-) 2-hydroxy-4-pentyl) ester, (meth) acrylic acid 2-{[5- (1 ′, 1 ′, 1′-trifluoro-2′-trifluoromethyl-2′-hy Proxy) propyl] bicyclo [2.2.1] heptyl} ester. Of these, (meth) acrylic acid 2- (1-ethoxycarbonyl-1,1-difluoro) butyl ester is preferred.

[D] The content ratio of the structural unit (V) in the fluorine atom-containing polymer is preferably 5 mol% to 90 mol% with respect to all the structural units constituting the [D] fluorine atom containing polymer. More preferred is ˜80 mol%.

[Structural unit (VI)]
The structural unit (VI) is a structural unit represented by the following formula (8).

In the formula (8), R ²⁷ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ²⁸ is a divalent hydrocarbon group having 1 to 30 carbon atoms. R ²⁹ is a hydrocarbon group having 1 to 10 carbon atoms having a fluorine atom. However, one part or all part of the hydrogen atom which the said bivalent hydrocarbon group and the said hydrocarbon group which has a fluorine atom have may be substituted.

Examples of the divalent hydrocarbon group having 1 to 30 carbon atoms represented by R ²⁸ include chain hydrocarbon groups such as methanediyl group and ethanediyl group; cyclopentanediyl group, norbornanediyl group, adamantanediyl group and the like. Alicyclic hydrocarbon groups; aromatic hydrocarbon groups such as phenylene groups and naphthylene groups.

Examples of the hydrocarbon group having 1 to 10 carbon atoms having a fluorine atom represented by R ²⁹ include a chain hydrocarbon group having a fluorine atom such as a trifluoromethyl group and a pentafluoroethyl group; a difluorocyclopentyl group, a tetra Examples include alicyclic hydrocarbon groups having a fluorine atom such as a fluorocyclohexyl group; aromatic hydrocarbon groups having a fluorine atom such as a fluorophenyl group and a trifluorophenyl group.

As the monomer giving the structural unit (VI), 3-trifluoromethylcarbonyloxy-1-adamantyl (meth) acrylate is preferable.

[D] The content ratio of the structural unit (VI) in the fluorine atom-containing polymer is preferably 10 mol% to 90 mol%, and preferably 20 mol%, based on all structural units constituting the [D] fluorine atom-containing polymer. More preferred is ˜80 mol%.

[Other structural units]
[D] The fluorine atom-containing polymer may have, as other structural units, the structural unit (II) for enhancing etching resistance, the structural unit (III) for enhancing solubility in a developer, and the like. Good. In addition, the [D] fluorine atom containing polymer may have 2 or more types of other structural units.

[D] The content of other structural units in the fluorine atom-containing polymer is usually 90 mol% or less with respect to all the structural units constituting the [D] fluorine atom-containing polymer, and is 5 mol% to 80 mol. % Is preferable, and 5 mol% to 75 mol% is more preferable.

[D] The content of the fluorine atom-containing polymer is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the [A] polymer. If the content of the [D] fluorine atom-containing polymer is less than 0.1 parts by mass, the effect of containing the [D] fluorine atom-containing polymer may not be sufficient. On the other hand, when the content of the [D] fluorine atom-containing polymer exceeds 20 parts by mass, the water repellency of the resist surface becomes too high, and development failure may occur.

[D] The fluorine atom content in the fluorine atom-containing polymer is usually 5% by mass or more, preferably 5% by mass to 50% by mass, with the total amount of the [D] fluorine atom-containing polymer being 100% by mass, 5 mass% to 45 mass% is more preferable. The fluorine atom content can be measured by ¹³ C-NMR. [D] The fluorine atom content in the fluorine atom-containing polymer is higher than that of the [A] polymer, so that the [D] fluorine atom-containing polymer and the photoresist composition containing the [A] polymer are formed. The water repellency of the resist film surface can be increased. As a result, it is not necessary to separately form an upper layer film during immersion exposure. In order to sufficiently exhibit the above effects, the difference between the fluorine atom content in the [A] polymer and the fluorine atom content in the [D] fluorine atom-containing polymer is 1% by mass or more. Is preferable, and it is more preferable that it is 3 mass% or more.

<[D] Method for Synthesizing Fluorine Atom-Containing Polymer>
[D] The fluorine atom-containing polymer can be synthesized, for example, by polymerizing a monomer giving each predetermined structural unit in a suitable solvent using a radical polymerization initiator.

Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane and n-decane;
Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane;
Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene;
Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene;
Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate and methyl propionate;
Ketones such as acetone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Examples thereof include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. In addition, these solvents may use 2 or more types together.

The reaction temperature in the above polymerization is usually 40 ° C to 150 ° C, preferably 50 ° C to 120 ° C. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

[D] The Mw of the fluorine atom-containing polymer is preferably 2,000 to 10,000, and more preferably 2,500 to 7,000. [D] When the Mw of the fluorine atom-containing polymer is less than 2,000, a sufficient receding contact angle cannot be obtained. On the other hand, if the Mw of the [D] fluorine atom-containing polymer exceeds 10,000, the developability when used as a resist tends to be lowered.

[D] The ratio (Mw / Mn) between the Mw of the fluorine atom-containing polymer and the polystyrene-equivalent number average molecular weight (Mn) by the GPC method is preferably 1.1 to 1.7.

<Other optional components>
The said photoresist composition may contain other arbitrary components, such as an uneven distribution promoter, surfactant, and a sensitizer, in the range which does not impair the effect of this invention. In addition, the said photoresist composition may contain 2 or more types of said other arbitrary components.

[Uneven distribution promoter]
The uneven distribution accelerator has the effect of segregating the [D] fluorine atom-containing polymer more efficiently on the resist film surface. The photoresist composition contains this uneven distribution accelerator, whereby the addition amount of the [D] fluorine atom-containing polymer can be reduced as compared with the conventional case. As a result, elution of components from the resist film to the immersion liquid can be further suppressed, or immersion exposure can be performed at higher speed without impairing basic resist characteristics such as LWR performance, development defects, and pattern collapse resistance. be able to. As such an uneven distribution promoter, a low molecular compound having a relative dielectric constant of 30 or more and 200 or less and a boiling point at 1 atm of 100 ° C. or more is used. For example, a lactone compound, a carbonate compound, a nitrile compound, a polyhydric alcohol, etc. Is mentioned.

Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, norbornane lactone, and the like.

Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate and the like.

Examples of the nitrile compound include succinonitrile.

Examples of the polyhydric alcohol include glycerin.

Of these uneven distribution promoters, γ-butyrolactone is preferred.

Two or more kinds of uneven distribution promoters may be used in combination. The content of the uneven distribution promoter is preferably 10 parts by mass or more and 500 parts by mass or less, and more preferably 20 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the [A] polymer.

[Surfactant]
Surfactants have the effect of improving coatability, striation, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. Nonionic surfactants such as stearate are listed. Examples of commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, manufactured by Tochem Products), MegaFac F171, F173 (above, manufactured by Dainippon Ink & Chemicals), Fluorad FC430, FC431 ( As above, manufactured by Sumitomo 3M, Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Industry) Manufactured) and the like.

[Sensitizer]
The sensitizer exhibits the effect of increasing the amount of [B] acid generators produced, and has the effect of improving the “apparent sensitivity” of the photoresist composition. Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like.

<Method for preparing photoresist composition>
The photoresist composition includes, for example, an [A] polymer, a [B] acid generator, a [C] acid diffusion controller, a [D] fluorine atom-containing polymer, and other optional components as necessary in an organic solvent. Is mixed at a predetermined ratio. Moreover, it is preferable to filter the obtained liquid mixture with a filter with a pore diameter of about 0.20 μm. The photoresist composition is preferably used in a state dissolved or dispersed in a suitable organic solvent.

Any organic solvent can be used as long as it can uniformly dissolve or disperse each component. Examples of the organic solvent include alcohols, ethers, ketones, amides, esters and the like. In addition, these organic solvents can use 2 or more types together.

Examples of alcohols include methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec -Pentanol, tert-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-he Monoalcohols such as butadecyl alcohol, furfuryl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 Polyhydric alcohols such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether and dipropylene glycol monopropyl ether, and the like.

Examples of ethers include diethyl ether, dipropyl ether, dibutyl ether, diphenyl ether, methoxybenzene and the like.

Examples of ketones include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, and methyl-n-hexyl. Examples include ketones such as ketone, di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, and acetophenone.

Examples of amides include N, N′-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N -Methylpropionamide, N-methylpyrrolidone and the like.

Examples of esters include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-acetate Butyl, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, methyl acetoacetate , Ethyl acetoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol acetate Mono-n-butyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, glycol diacetate Methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, Examples include diethyl malonate, dimethyl phthalate, and diethyl phthalate.

Examples of the hydrocarbons include n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane, Aliphatic hydrocarbons such as methylcyclohexane;
Fragrances such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene, n-amylnaphthalene Group hydrocarbons and the like.

Of these, cyclohexanone, propylene glycol monomethyl ether acetate, and ethyl lactate are preferable.

<Method for forming resist pattern>
The resist pattern forming method of the present invention includes (1) a step of forming a resist film on a substrate using the photoresist composition (hereinafter also referred to as “step (1)”), and (2) via a photomask. A step of exposing the resist film by radiation irradiation (hereinafter also referred to as “step (2)”), and (3) a step of developing the exposed resist film (hereinafter also referred to as “step (3)”). Have When this resist pattern forming method is used, a fine resist pattern having a small MEEF and LWR can be formed. Hereinafter, each process is explained in full detail.

[Step (1)]
In this step, the photoresist composition is applied onto a substrate to form a resist film. As the substrate, for example, a conventionally known substrate such as a silicon wafer or a wafer coated with aluminum can be used. Further, for example, an organic or inorganic lower antireflection film disclosed in Japanese Patent Publication No. 6-12452 and Japanese Patent Application Laid-Open No. 59-93448 may be formed on the substrate.

Examples of the application method include spin coating, spin coating, roll coating, and the like. The film thickness of the resist film to be formed is usually 10 nm to 100 nm, preferably 10 nm to 80 nm.

After applying the photoresist composition, if necessary, the solvent in the coating film may be volatilized by soft baking (SB). The temperature of SB is appropriately selected depending on the composition of the photoresist composition, but is usually about 30 ° C. to 200 ° C., preferably 50 ° C. to 150 ° C. The SB time is usually 5 to 600 seconds, and preferably 10 to 300 seconds.

[Step (2)]
In this step, a desired region of the resist film formed in step (1) is exposed through a mask. Further, in this step, exposure may be performed by reducing and projecting through an immersion liquid as necessary. For example, an isotrench pattern can be formed by performing reduced projection exposure on a desired region through an isoline pattern mask. Moreover, you may perform exposure twice or more. When performing exposure twice or more, it is preferable to perform exposure continuously. In the case of performing multiple exposures, for example, a first reduced projection exposure is performed on a desired area via a line and space pattern mask, and then the second is so that the line intersects the exposed portion where the first exposure has been performed. Reduced projection exposure is performed. The first exposure part and the second exposure part are preferably orthogonal. By being orthogonal, it becomes easy to form a perfect circular contact hole pattern in the unexposed area surrounded by the exposed area.

Examples of the immersion liquid used for exposure include water and a fluorine-based inert liquid. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient that is as small as possible so as to minimize distortion of the optical image projected onto the film. When the exposure light source is ArF excimer laser light (wavelength 193 nm), water is preferable from the viewpoints of availability and ease of handling in addition to the above-described viewpoints. When water is used, an additive that decreases the surface tension of water and increases the surface activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist layer on the wafer and can ignore the influence on the optical coating on the lower surface of the lens. The water used is preferably distilled water.

The radiation used for exposure is appropriately selected according to the type of [B] acid generator, and examples thereof include ultraviolet rays, far ultraviolet rays, X-rays, and charged particle beams. Among these, far ultraviolet rays represented by ArF excimer laser light and KrF excimer laser light (wavelength 248 nm) are preferable, and ArF excimer laser light is more preferable. The exposure conditions such as the exposure amount are appropriately selected according to the composition of the photoresist composition and the type of additive. In the resist pattern forming method of the present invention, the exposure process may be performed a plurality of times, and the plurality of exposures may be performed using the same light source or different light sources, but ArF excimer laser is used for the first exposure. It is preferable to use light.

It is preferable to perform post-exposure baking (PEB) after the exposure. By performing PEB, the dissociation reaction of the acid dissociable group in the photoresist composition can proceed smoothly. The heating conditions for PEB are usually 30 ° C. or higher and lower than 200 ° C., preferably 50 ° C. or higher and lower than 150 ° C. At a temperature lower than 30 ° C., the dissociation reaction may not proceed smoothly. On the other hand, at a temperature of 200 ° C. or higher, the acid generated from the [B] acid generator diffuses widely to the unexposed area and is good. There is a possibility that a pattern cannot be obtained. The PEB time is usually 5 to 600 seconds, preferably 10 to 300 seconds.

[Step (3)]
In this step, the resist film heated after exposure is developed with a developer. After development, it is common to wash with water and dry. Examples of the developer include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyl Dimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4.3 0.0] -5-Nonene, an alkaline aqueous solution in which at least one alkaline compound is dissolved is preferable.

As a developing method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is allowed to stand for a certain time (a paddle method) ), A method of spraying the developer on the substrate surface (spray method), a method of continuously applying the developer while scanning the developer coating nozzle on the substrate rotating at a constant speed (dynamic dispensing method) Etc.

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to the examples. The measuring method of various physical property values is shown below.

[ ¹ H-NMR analysis and ¹³ C-NMR analysis]
For ¹ H-NMR analysis of the compound and ¹³ C-NMR analysis of the polymer, a nuclear magnetic resonance apparatus (JNM-EX400, manufactured by JEOL Ltd.) was used, and deuterated chloroform was used as a measurement solvent.

<Synthesis of monomer>
[Synthesis Example 1] Synthesis of Compound (M-9) To a 1 L three-necked reactor dried with a dropping funnel and a condenser, 13.1 g (200 mmol) of zinc powder (Aldrich particle size of 150 μm or less) was added, and argon was added. After making the atmosphere, 240 mL of tetrahydrofuran (THF) was added, and 1.9 mL (15 mmol) of chlorotrimethylsilane was added while stirring with a magnetic stirrer, and the mixture was stirred at 20 ° C. to 25 ° C. for 30 minutes. A solution prepared by dissolving 20.0 g (200 mmol) of 2-methyltetrahydrofuran-3-one in 40 mL of THF was added thereto. Next, a solution of 34.8 g (180 mmol) of ethyl (2-bromomethyl) acrylate in 50 mL of THF was added dropwise. After dropping, the mixture was stirred at room temperature for 2 hours. After confirming the completion of the reaction by gas chromatography, an aqueous ammonium chloride solution and ethyl acetate were added to separate the layers. The obtained organic layer was washed successively with water and saturated brine. Thereafter, the organic layer was dried and concentrated under reduced pressure. Thereafter, distillation under reduced pressure was performed, and the compound (6-methyl-3-methylene-1,7-dioxaspiro [4.4] nonan-2-one) represented by the following formula (M-9) as a transparent oily substance20. 4 g (yield 67%, purity 99%) was obtained.

[Synthesis Example 2] Synthesis of Compound (M-10) First, 1,004 g (8.64 mol) of 1,4-cyclohexanediol was added to a 20 L reactor, and 4,320 mL of THF was added thereto. Stir with a stirrer. To the reactor was added 21.71 g (86.39 mmol) of pyridinium p-toluenesulfonate, followed by 726.73 g (8.64 mol) of 3,4-dihydro-2H-pyran and allowed to react at room temperature for 12 hours. Thereafter, 17.28 g (170.77 mmol) of triethylamine was added to stop the reaction, and the mixture was concentrated. The concentrated solution was partitioned between hexane and water, and NaCl was added to the obtained aqueous layer until saturation, followed by extraction with methylene chloride. The obtained organic layer was dried over magnesium sulfate and concentrated under reduced pressure to obtain 737 g (3.68 mol, 43% yield) of a compound (M-10-A) represented by the following formula (M-10-A). )Obtained.

The ¹ H-NMR data of the obtained (M-10-A) is shown below.
¹ H-NMR (measurement solvent: deuterated chloroform, reference material: tetramethylsilane) δ: 1.24-1.1.9 (m, 13H), 1.94-2.05 (m, 2H), 3.45- 3.53 (m, 1H), 3.59-3.70 (m, 1H), 3.71-3.78 (m, 1H), 3.87-3.95 (m, 1H), 4. 67-4.71 (m, 1H)

Next, 300 g (1.5 mol) of (M-10-A) obtained above was added to a 5 L three-necked reactor, and 1200 mL of methylene chloride and 0.228 g of 2-azaadamantane-N-oxyl ( 1.5 mmol), 17.85 g (150 mmol) of potassium bromide, and 450 mL of a saturated aqueous sodium hydrogen carbonate solution were sequentially added, and the mixture was stirred with a mechanical stirrer. The reactor was cooled to 0 ° C., and a solution prepared by mixing 1,913 g of a 7% sodium hypochlorite aqueous solution and 450 mL of a saturated sodium hydrogen carbonate aqueous solution was added dropwise over 3 hours. After completion of dropping, the mixture was stirred at 0 ° C. for 30 minutes, and then 100 mL of a saturated aqueous sodium thiosulfate solution was added to stop the reaction and liquid separation was performed. The obtained organic layer was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure to give 214 g (1) of a compound (M-10-B) represented by the following formula (M-10-B). .07 mol, yield 71%).

The ¹ H-NMR data of the obtained (M-10-B) is shown below.
¹ H-NMR (measurement solvent: deuterated chloroform, reference material: tetramethylsilane) δ: 1.51-2.16 (m, 10H), 2.22-2.35 (m, 2H), 2.50- 2.69 (m, 2H), 3.49-3.56 (m, 1H), 3.88-3.95 (m, 1H), 4.05-4.11 (m, 1H), 4. 74-4.78 (m, 1H)

Subsequently, 94.1 g (1.44 mol) of zinc powder (Wako Pure Chemicals, Wako Special Grade) was added to a 3 L three-necked reactor equipped with a dropping funnel and a condenser, and after making the atmosphere nitrogen, tetrahydrofuran (THF ) While adding 1.3 L and stirring with a magnetic stirrer, 6.3 mL (50 mmol) of chlorotrimethylsilane was added and stirred at 20 to 25 ° C. for 10 minutes. Thereto was added a solution obtained by dissolving 199.3 g (1.0 mol) of (M-10-B) obtained above in 100 mL of THF. Next, a solution of 231.7 g (1.2 mol) of ethyl (2-bromomethyl) acrylate in 100 mL of THF was added to the dropping funnel at 25 ° C., and dropping was started. After dropping for 3 minutes, the temperature of the reaction solution rose to 40 ° C., so the reactor was cooled with a water bath. Subsequently, dropwise addition was performed so that the reaction temperature was kept in the range of 30 ° C. to 40 ° C. It took 2 hours to complete the dropping. Thereafter, the mixture was stirred for 30 minutes. After confirming the completion of the reaction by gas chromatography, the reaction solution was cooled to 25 ° C. Subsequently, 1 L of a saturated aqueous ammonium chloride solution was added and mixed, and the reaction was stopped by stirring for 1 hour. The generated salt and excess zinc that was not used in the reaction were removed by celite filtration, and the resulting solution was concentrated using an evaporator. When ethyl acetate and a saturated aqueous solution of sodium hydrogen carbonate were added to the concentrate with stirring, a white precipitate was formed. Therefore, the white precipitate was removed by filtration, and then the organic layer was separated using a separatory funnel. The obtained organic layer was dried and concentrated under reduced pressure. This solid was recrystallized using ethyl acetate as a solvent to obtain 254 g (yield 95.4%, purity 98%) of a compound represented by the following formula (M-10-C) as a transparent liquid.

¹ H-NMR data is shown below.
¹ H-NMR (measurement solvent: deuterated chloroform, reference material: tetramethylsilane) δ: 1.51-2.17 (m, 14H), 2.72 (dt, J = 8.8, 2.8 Hz, 2H ), 3.52-3.47 (m, 1H), 3.67-3.75 (m, 1H), 3.85-3.95 (m, 1H), 4.65 (t, J = 3) .6 Hz, 0.5 H), 4.73 (t, J = 3.6 Hz, 0.5 H), 5.60-5.64 (m, 1 H), 6.22-6.26 (m, 1 H)

Thereafter, 200 g (751 mol) of the compound (M-10-C) obtained above was added to a 1 L reactor, and 1.0 g of concentrated hydrochloric acid diluted with 200 ml of methanol was stirred with a magnetic stirrer. Methanol solution was added and stirred at 20-25 ° C. for 30 minutes. After confirming the disappearance of the raw material by gas chromatography, sodium hydrogen carbonate powder was gradually added to neutralize the solution to pH 7. After filtering the salt that has been deposited with neutralization, 500 ml of ethyl acetate is added, the organic solvent is removed with an evaporator, and the product is concentrated. This concentration operation was repeated twice and then purified by column chromatography to obtain 117 g (yield: 85.5%, purity: 99%) of a compound represented by the following formula (M-10).

¹ H-NMR data is shown below.
¹ H-NMR (measurement solvent: deuterated chloroform, reference material: tetramethylsilane) δ: 1.51-2.09 (m, 8H), 2.72 (t, J = 2.8 Hz, 1H), 2. 76 (t, J = 2.8 Hz, 1H), 3.67-3.77 (m, 0.5H), 3.96-4.04 (m, 0.5H), 5.62-5.68 (M, 1H), 6.22-6.28 (m, 1H)

<Synthesis of polymer>
Each monomer used for the synthesis of [A] polymer and [D] fluorine atom-containing polymer is shown below.

The compounds (M-9), (M-10) and (M-11) have the structural unit (I) and the compounds (M-1), (M-2), (M-3) and (M- 4) is structural unit (II), compound (M-5) is structural unit (III), compound (M-6) is structural unit (IV), and compound (M-7) is structural unit (V). And compound (M-8) gives structural unit (VI), respectively.

<[A] Synthesis of polymer>
[Synthesis Example 3]
7.3 g (20 mol%) of the above compound (M-9), 18.2 g (50 mol%) of compound (M-1) and 14.5 g (30 mol%) of compound (M-5) were added to 80 g of 2- A monomer solution was prepared by dissolving in butanone and adding 3.56 g of AIBN (10 mol% with respect to the total number of moles of monomers) as a radical initiator. Subsequently, a 200 mL three-necked flask containing 40 g of 2-butanone was purged with nitrogen for 30 minutes and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. The cooled polymerization solution was put into 800 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 160 g of methanol, then filtered and dried at 50 ° C. for 17 hours to synthesize a white powdery polymer (A-1). Mw of the polymer (A-1) was 4,500, and Mw / Mn was 1.4. As a result of ¹³ C-NMR analysis, the content of each structural unit derived from (M-9), (M-1), and (M-5) was 18 mol%, 48 mol%, and 34 mol%, respectively. .

[Synthesis Examples 4 to 11]
Each polymer was synthesized in the same manner as in Synthesis Example 3 except that the monomers and radical initiators of the types and amounts shown in Table 1 below were used. The total mass of the monomers used was 40 g. Table 1 shows Mw and Mw / Mn of each polymer synthesized. “-” Indicates that the corresponding monomer was not used.

<[D] Synthesis of fluorine atom-containing polymer>
[Synthesis Example 12]
A monomer solution was prepared by dissolving 43 g (70 mol%) of the compound (M-2) and 17 g (30 mol%) of the compound (M-6) in 60 g of 2-butanone and adding 3.87 g of AIBN. A 300 mL three-necked flask charged with 30 g of 2-butanone was purged with nitrogen for 30 minutes, and then the reactor was heated to 80 ° C. with stirring, and the monomer solution prepared as described above was added to the flask using a dropping funnel. It was added dropwise over time. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization reaction, the polymerization solution was cooled with water to 30 ° C. or less, and poured into a 600 g methanol: water = 8: 2 solution to precipitate the resin. After removing the supernatant solution, 120 g of methanol was added to the precipitated resin to wash the resin. After removing the supernatant, it was dried at 50 ° C. for 17 hours to synthesize a polymer (D-1). The polymer (D-1) had an Mw of 4,800, an Mw / Mn of 1.4, and a fluorine atom content ratio of 4% by mass. The fluorine atom content was measured by ¹³ C-NMR analysis. The content ratios of the structural unit (II) and the structural unit (IV) were 68.5 mol% and 31.5 mol%, respectively.

[Synthesis Example 13]
A monomer solution prepared by dissolving 14.3 g (30 mol%) of the above compound (M-2) and 45.7 g (70 mol%) of the compound (M-7) in 60 g of 2-butanone and charging 3 g of AIBN was prepared. did. A 300 mL three-necked flask charged with 30 g of 2-butanone was purged with nitrogen for 30 minutes, and then the reactor was heated to 80 ° C. with stirring, and the monomer solution prepared as described above was added to the flask using a dropping funnel. It was added dropwise over time. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization reaction, the polymerization solution was cooled with water to 30 ° C. or less, and poured into a 600 g methanol: water = 8: 2 solution to precipitate the resin. After removing the supernatant solution, 120 g of methanol was added to the precipitated resin to wash the resin. After removing the supernatant, it was dried at 50 ° C. for 17 hours to synthesize a polymer (D-2). The polymer (D-2) had an Mw of 4,200, an Mw / Mn of 1.3, and a fluorine atom content ratio of 5% by mass. The content rates of the structural unit (II) and the structural unit (V) were 32 mol% and 68 mol%, respectively.

[Synthesis Example 14]
Monomer solution in which 11.4 g (30 mol%) of the compound (M-4) and 48.6 g (70 mol%) of the compound (M-8) were dissolved in 60 g of 2-butanone and 2.4 g of AIBN was added. Prepared. A 300 mL three-necked flask charged with 30 g of 2-butanone was purged with nitrogen for 30 minutes, and then the reactor was heated to 80 ° C. with stirring, and the monomer solution prepared as described above was added to the flask using a dropping funnel. It was added dropwise over time. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization reaction, the polymerization solution was cooled with water to 30 ° C. or less, and poured into a 600 g methanol: water = 8: 2 solution to precipitate the resin. After removing the supernatant solution, 120 g of methanol was added to the precipitated resin to wash the resin. After removing the supernatant, it was dried at 50 ° C. for 17 hours to synthesize a polymer (D-3). The polymer (D-3) had an Mw of 4,500, an Mw / Mn of 1.4, and a fluorine atom content ratio of 5% by mass. The content rates of the structural unit (II) and the structural unit (VI) were 29 mol% and 71 mol%, respectively.

Table 2 shows the types and amounts of monomers used in Synthesis Examples 12 to 14, the content ratio of the structural units of the obtained [D] fluorine atom-containing polymer, Mw, and Mw / Mn.

<Preparation of photoresist composition>
Each component used for preparation of each photoresist composition is shown below.

[[B] acid generator]
Each structural formula and the van der Waals volume of the generated acid are shown below.
B-1: Compound represented by the following formula (B-1) (Van der Waals volume: 3.34 × 10 ⁻²⁸ m ³ )
B-2: Compound represented by the following formula (B-2) (Van der Waals volume: 3.93 × 10 ⁻²⁸ m ³ )
B-3: Compound represented by the following formula (B-3) (Van der Waals volume: 2.94 × 10 ⁻²⁸ m ³ )
b-1: Compound represented by the following formula (b-1) (Van der Waals volume: 1.65 × 10 ⁻²⁸ m ³ )
b-2: Compound represented by the following formula (b-2) (Van der Waals volume: 2.02 × 10 ⁻²⁸ m ³ )
b-3: Compound represented by the following formula (b-3) (Van der Waals volume: 1.65 × 10 ⁻²⁸ m ³ )

[[C] acid diffusion controller]
C-1: Compound represented by the following formula (C-1) C-2: Compound represented by the following formula (C-2) C-3: Compound C- represented by the following formula (C-3) 4: Compound represented by the following formula (C-4)

[[E] organic solvent]
E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone

[[F] uneven distribution promoter]
F-1: γ-butyrolactone

[Example 1]
[A] 100 parts by mass of (A-1) as a polymer, [B] 11 parts by mass of (B-1) as an acid generator, [C] 5 parts by mass of (C-3) as an acid diffusion controller [D] 3 parts by mass of (D-1) as a fluorine atom-containing polymer and 30 parts by mass of (F-1) as an uneven distribution promoter were mixed, and the resulting mixture was mixed with a pore size of 0.20 μm. A photoresist composition was prepared by filtration through a filter.

[Examples 2 to 6 and Comparative Examples 1 to 7]
Each photoresist composition was prepared in the same manner as in Example 1 except that the components of the types and contents shown in Table 3 were mixed.

<Formation of resist pattern>
A lower antireflection film having a thickness of 105 nm was formed on the surface of a 12-inch silicon wafer by using a lower antireflection film forming composition (ARC66, manufactured by Nissan Chemical Industries). After applying each photoresist composition on the lower antireflection film, soft baking (SB) was performed for 60 seconds at the temperature shown in Table 3 to form a resist film having a thickness of 75 nm. Next, this resist film was exposed through a mask pattern using an ArF excimer laser immersion exposure apparatus (NSR S610C, manufactured by NIKON) under the conditions of NA = 1.3, ratio = 0.800, and Annular. After exposure, post-exposure baking (PEB) was performed for 60 seconds at the PEB temperatures shown in Table 3 below. Then, it developed with 2.38 mass% TMAH aqueous solution, wash | cleaned and dried with water, and formed the positive resist pattern. This positive resist pattern is a 1: 1 line and space with a line width of 50 nm formed through a mask for forming a 50 nm line and 100 nm pitch with a target dimension. A scanning electron microscope (CG-4000, manufactured by Hitachi High-Technologies) was used for measuring the resist pattern. When forming the pattern, the line width formed through a one-to-one line-and-space mask with a dimension of 50 nm optimizes the exposure amount (mJ / cm ² ) formed in a one-to-one line-and-space with a line width of 50 nm. The exposure amount was used.

<Evaluation>
The following evaluation was implemented about the formed resist pattern. The results are shown in Table 3.

[sensitivity]
The optimum exposure amount was evaluated as sensitivity (mJ / cm ² ). When the sensitivity is 50 (mJ / cm ² ) or less, it can be determined that the sensitivity is good.

[LWR]
The resist pattern was observed from above the pattern using a scanning electron microscope (CG4000, manufactured by Hitachi High-Technologies). A total of 50 line widths were measured at arbitrary points, and a 3-sigma value was obtained from the distribution of the measured values, which was defined as LWR (nm). When the value of LWR is 5.5 (nm) or less, it can be determined that the shape of the formed resist pattern is good. A scanning electron microscope (CG4000, manufactured by Hitachi High-Technologies) was also used for measuring the line width.

[MEEF]
Five types of mask sizes (48.0 nmL / 100 nmP, 49.0 nmL / 100 nmP, 50.0 nmL / 100 nmP, 51.0 nmL / 100 nmP, 52.0 nmL / 100 nmP) with the above-mentioned scanning electron microscope and the above-mentioned optimum exposure dose The dimension of the pattern resolved in (1) was measured. The measurement results were plotted with the mask size on the horizontal axis and the line width formed with each mask size on the vertical axis, and the slope of the graph was determined by the least square method, and this slope was defined as MEEF. MEEF indicates that the closer the value is to 1, the better the mask reproducibility. When the MEEF value is 3.5 or less, it can be determined that the MEEF value is good.

From the results in Table 3, it was shown that the photoresist composition of the present invention was superior in MEEF performance and LWR performance as compared with the photoresist composition of the comparative example.

The present invention can provide a photoresist composition excellent in MEEF performance and LWR performance, and a method for forming a resist pattern. Therefore, the photoresist composition can be suitably used in a lithography process that requires further miniaturization.

Claims (9)

1. [A] a polymer having a structural unit (I) represented by the following formula (1), and [B] an acid generator,
   [B] A photoresist composition in which the van der Waals volume of the acid generated from the acid generator is 2.1 × 10 ⁻²⁸ m ³ or more.
   

   

   (In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² and R ³ are each independently a hydrogen atom, a fluorine atom, a hydroxy group or a carbon number. Represents a monovalent organic group having 1 to 20 or a ring structure having 3 to 20 carbon atoms constituted by carbon atoms to which R ² and R ³ are combined and bonded to each other, provided that R ² and R 3 ^It is not the case where both are hydroxy groups ^3. R ⁴ and R ⁵ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, or R ⁴ and R ⁵ are combined with each other. And represents a ring structure having 3 to 20 carbon atoms and a carbon atom to which they are bonded, n is an integer of 1 to 4. When n is 2 or more, a plurality of R ² and R ³ are the same. But it may be different.)
2. [B] The photoresist composition according to claim 1, wherein the acid generated from the acid generator has an alicyclic structure having 6 to 15 carbon atoms.
3. [B] The photoresist composition according to claim 1, wherein the acid generator includes a cation and an anion, and the anion is represented by the following formula (3).
   

   

   (In Formula (3), R ¹⁰ is a monovalent group having an alicyclic structure having 6 to 15 carbon atoms. Y ¹ and Y ² are each independently a single bond, an oxygen atom, or a nitrogen atom. R ¹¹ is a divalent hydrocarbon group having 1 to 20 carbon atoms, and R ¹² is a (q + 1) valent group having 1 to 20 carbon atoms. In addition, when q is 1, R ¹² may be a single bond, and R ^f1 and R ^f2 each independently represent a hydrogen atom, a fluorine atom, or an alkyl having 1 to 30 carbon atoms. Or a fluorinated alkyl group having 1 to 30 carbon atoms, p is an integer of 0 to 2, q is an integer of 1 to 3, and r is an integer of 0 to 5, provided that When there are a plurality of R ¹⁰ , Y ¹ , Y ² , R ¹¹ , R ^f1 and R ^f2 , a plurality of R ¹⁰ , Y ¹ , Y ² , R ¹¹ , R ^f1 and R ^f2 may be the same or different.)
4. 4. The photoresist composition according to claim 3, wherein the anion has at least one structure selected from the group consisting of an adamantane structure and a norbornane structure.
5. In the above formula (1), at least one of R ² , R ³ , R ⁴ and R ^{5 is} a monovalent organic group having 1 to 20 carbon atoms, and the monovalent organic group includes a hetero atom and a halogen atom. The photoresist composition of claim 1 comprising at least one atom selected from the group consisting of:
6. The photoresist composition according to claim 1, wherein R ⁴ and R ⁵ in the formula (1) represent a ring structure having 3 to 20 carbon atoms that is configured together with the carbon atoms to which they are bonded.
7. The photoresist composition according to claim 6, wherein the ring structure has a polar group.
8. [A] The photoresist composition according to claim 1, wherein the polymer further has a structural unit (II) represented by the following formula (2).
   

   

   (In the formula (2), R ⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁷ is an alkyl group having 1 to 4 carbon atoms or an alicyclic group having 4 to 20 carbon atoms. R ⁸ and R ⁹ are each independently an alkyl group having 1 to 4 carbon atoms or an alicyclic group having 4 to 20 carbon atoms, or R ⁸ and R ⁹ are combined with each other Represents a divalent alicyclic group constituted with carbon atoms to be bonded.)
9. (1) A step of forming a resist film on a substrate using the photoresist composition according to claim 1;
   (2) A resist pattern forming method including a step of exposing the resist film by radiation irradiation through a photomask, and (3) a step of developing the exposed resist film.