WO2012046543A1

WO2012046543A1 - Resist pattern formation method and radiation-sensitive resin composition

Info

Publication number: WO2012046543A1
Application number: PCT/JP2011/070770
Authority: WO
Inventors: 亘史伊藤; 宏和榊原; 雅史堀; 泰一古川
Original assignee: Jsr株式会社
Priority date: 2010-10-04
Filing date: 2011-09-12
Publication date: 2012-04-12
Also published as: TW201219972A

Abstract

The present invention provides a resist pattern formation method comprising: (1) a resist film formation step of applying a radiation-sensitive resin composition to a substrate; (2) an exposure step; and (3) a step of developing using a developing solution containing 80 mass% or more of an organic solvent; wherein the radiation-sensitive resin composition includes: [A] a base polymer having an acid-dissociable group; [B] a radiation-sensitive acid generator containing a cation and an anion, the anion having an alicyclic group and the ratio (F/C) of fluorine atoms and carbon atoms of the anion being 0.1 to 0.5; and [C] a fluorine-containing polymer in which the content ratio of fluorine atoms is higher than that of the polymer of [A].

Description

Resist pattern forming method and radiation-sensitive resin composition

The present invention relates to a resist pattern forming method and a radiation sensitive resin composition.

With the miniaturization of various electronic device structures such as semiconductor devices and liquid crystal devices, miniaturization of resist patterns in the lithography process is required. At present, it is possible to form a fine resist pattern having a line width of about 90 nm using, for example, an ArF excimer laser, but in the future, a demand for forming a finer resist pattern is expected.

On the other hand, according to the immersion exposure, it is said that even when a light source having the same exposure wavelength is used, the same high resolution as that when a light source having a shorter wavelength is used can be achieved. Therefore, immersion exposure is attracting attention as a technique for achieving high resolution while reducing an increase in cost in the manufacture of semiconductor elements that require a large capital investment.

However, in immersion exposure, the resist film changes in quality due to elution of substances contained in the resist into the immersion medium and the performance is degraded, and the refractive index of the immersion medium is locally affected by the eluted substances. There may be inconveniences that adversely affect the lithographic properties due to the change and contamination of the lens surface by the eluted substances (see WO 04/068242 pamphlet). As a solution to such inconvenience, it is conceivable to increase the resolving power by utilizing the characteristics of the chemically amplified resist material. As such a technique, for example, a double exposure technique or a double patterning technique is known. Among them, as a technique for increasing resolution without increasing the number of steps using an existing apparatus, a technique using an organic solvent having a polarity lower than that of an alkaline aqueous solution as a developer is disclosed (see Japanese Patent Application Laid-Open No. 2000-199953). This is because by using an organic solvent, the optical contrast can be increased, and as a result, a fine resist pattern can be formed. However, in the formation of a resist pattern using such an organic solvent, when a conventional resin composition is used for a resist film, an unresolved hole pattern, that is, a so-called missing contact hole occurs.

In the resist pattern formation using an organic solvent for the developer as described above, a combination of a resist pattern formation method and a radiation sensitive resin composition in which generation of a missing contact hole is suppressed has not been found to date.

International Publication No. 04/068242 Pamphlet JP 2000-199953 A

The present invention has been made on the basis of the above circumstances, and the object thereof is a method for forming a resist pattern that has less occurrence of missing contact holes when a developer containing an organic solvent is used and has excellent lithography properties, and It is to provide a radiation sensitive resin composition.

The invention made to solve the above problems is
(1) a resist film forming step of applying a radiation sensitive resin composition on a substrate;
(2) an exposure step, and (3) a resist pattern forming method including a step of developing using a developer containing 80% by mass or more of an organic solvent,
The radiation sensitive resin composition is
[A] Base polymer having an acid dissociable group (hereinafter sometimes referred to as “[A] polymer”)
[B] Generation of a radiation-sensitive acid containing a cation and an anion having an alicyclic group, wherein the ratio of the number of atoms (F / C) of fluorine and carbon in the anion is 0.1 or more and 0.5 or less (Hereinafter sometimes referred to as “[B] acid generator”), and [C] a polymer containing a fluorine atom and having a higher fluorine atom content than the [A] polymer (hereinafter referred to as “[C] heavy polymer”). May be referred to as “union”),
It is characterized by containing.

The [B] acid generator contained in the radiation sensitive resin composition has an alicyclic group, and the atomic ratio (F / C) of fluorine atom to carbon atom is 0.1 or more and 0.5. Contains anions that are: [B] Since the acid generator has the above specific structure, the acid-dissociable group of the [A] polymer is dissociated by the acid generated from the [B] acid generator at the time of exposure, so that the developer containing the organic solvent On the other hand, it becomes insoluble and a resist pattern can be formed. [B] The reason why the generation of the missing contact hole is suppressed by the acid generator having the above specific structure is not necessarily clear, but [B] the hydrophobicity of the acid generator is moderately determined with F / C in the above specific range. By making it within such a range, the [B] acid generator is prevented from being unevenly distributed on the resist film surface, and the [B] acid generator has an alicyclic group, whereby the phase with the [A] polymer is prevented. It is considered that the solubility is improved and the [B] acid generator is uniformly dispersed in the resist film. As a result, it is considered that the deprotection reaction of the polymer specifically on the outermost surface of the resist coating film is suppressed, and the occurrence of missing contact holes can be effectively prevented. Further, by using the [C] polymer having a higher fluorine atom content than the [A] polymer, the [C] polymer is unevenly distributed on the resist film surface at the time of applying the resist, thereby imparting water repellency to the resist and soaking the liquid. A resist film more suitable for exposure can be formed. Therefore, in the resist pattern forming method in which development is performed using a developer containing 80% by mass or more of an organic solvent, the occurrence of missing contact holes is suppressed and the lithography properties are excellent by combining the composition having the specific structure. Resist pattern formation is possible.

[A] The acid dissociable group of the polymer preferably has a monocyclic or polycyclic alicyclic hydrocarbon group. Thereby, it is excellent in acid dissociation property and sufficient sensitivity can be obtained.

[B] The anion of the acid generator is preferably represented by the following formula (1).

(In Formula (1), R ¹ is a monovalent organic group containing a monocyclic or polycyclic alicyclic group. N is 1 or 2. R ^f1 and R ^f2 are each independently. A hydrogen atom, a fluorine atom, or a fluorinated alkyl group having 1 to 4 carbon atoms, except when both R ^f1 and R ^f2 are hydrogen atoms, and each of R ^f1 and R ^f2 has a plurality of In this case, the plurality of R ^f1 and R ^f2 may be the same or different.)

[B] Since the anion of the acid generator has the above-mentioned specific structure, the [B] acid generator is more uniformly dispersed in the resist film, and effectively suppresses uneven generation of acid in the exposed area. Can do.

[B] The anion having an alicyclic group of the acid generator is preferably at least one anion selected from the group consisting of anions represented by the following formulas (2) to (5).

When the [B] acid generator contains the specific anion, the dispersibility of the [B] acid generator in the resist film is further improved, and the suppression of the occurrence of missing contact holes can be further enhanced.

The organic solvent contained in the developer is at least one solvent selected from the group consisting of alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and hydrocarbon solvents. Is preferred. Thus, by using a specific organic solvent, an appropriate combination with a predetermined resist composition can be realized, and a resist pattern with more excellent lithography characteristics can be obtained.

In addition, the radiation sensitive resin composition of the present invention,
[A] a base polymer having an acid dissociable group,
[B] Generation of a radiation-sensitive acid containing a cation and an anion having an alicyclic group, wherein the ratio of the number of atoms (F / C) of fluorine and carbon in the anion is 0.1 or more and 0.5 or less And [C] a fluorine atom, and a polymer having a fluorine atom content higher than that of the polymer [A]. According to the said radiation sensitive resin composition, generation | occurrence | production of a missing contact hole can be effectively suppressed in the resist pattern formation method using the developing solution containing an organic solvent.

The present invention is suitable for immersion exposure, and provides a resist pattern forming method and a radiation-sensitive resin composition that are excellent in lithography characteristics with less occurrence of missing contact holes when a developer containing an organic solvent is used. can do.

<Resist pattern formation method>
In the present invention, (1) a resist film forming step of applying a radiation-sensitive resin composition on a substrate, (2) an exposure step, and (3) development using a developer containing 80% by mass or more of an organic solvent. A resist pattern forming method including a step, wherein the radiation sensitive resin composition includes [A] a base polymer having an acid dissociable group, [B] a cation and an anion having an alicyclic group, A radiation-sensitive acid generator having an atomic number ratio (F / C) of an anion fluorine atom to carbon atom of 0.1 to 0.5, and [C] a fluorine atom, and a [A] polymer It is characterized by containing a polymer having a higher fluorine atom content. Hereinafter, each process is explained in full detail.

[Step (1)]
In this step, the composition used in the present invention 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 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 thickness of the resist film to be formed is usually 0.01 μm to 1 μm, preferably 0.01 μm to 0.5 μm.

After applying the composition, if necessary, the solvent in the coating film may be volatilized by pre-baking (PB). The heating conditions for PB are appropriately selected depending on the composition of the composition, but are usually about 30 to 200 ° C, preferably 50 to 150 ° C.

In order to prevent the influence of basic impurities contained in the ambient atmosphere, a protective film disclosed in, for example, Japanese Patent Laid-Open No. 5-188598 can be provided on the resist layer. Further, in order to prevent the acid generator and the like from flowing out of the resist layer, an immersion protective film disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-352384 can be provided on the resist layer. These techniques can be used in combination.

[Step (2)]
In this step, exposure is performed by reducing and projecting onto a desired region of the resist film formed in step (1) through a mask having a specific pattern and, if necessary, an immersion liquid. For example, the hole pattern can be obtained by performing reduction projection exposure on a substrate coated with a resist through a desired dot pattern mask and developing. For example, the trench pattern can be formed by performing reduced projection exposure on a desired region through an isoline pattern mask. The exposure may be performed twice or more depending on a desired pattern and a mask pattern. 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. In this way, a circular contact hole pattern can be formed in the unexposed part surrounded by the exposed part by making the first exposed part and the second exposed part orthogonal to each other. 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. In the case of excimer laser light (wavelength 193 nm), it is preferable to use water from the viewpoints of availability and easy handling in addition to the above-described viewpoints. 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 and KrF excimer laser (wavelength 248 nm) are preferable, and ArF excimer laser is more preferable. The exposure conditions such as the exposure amount are appropriately selected according to the composition of the composition, the type of additive, and the like. In the resist pattern forming method of the present invention, the exposure process may have a plurality of times, and the plurality of exposures may use the same light source or different light sources, but the ArF excimer laser is used for the first exposure. It is preferable to use light.

Moreover, it is preferable to perform post-exposure baking (PEB) after exposure. By performing PEB, the dissociation reaction of the acid dissociable group in the composition can proceed smoothly. The heating conditions for PEB are usually 30 ° C. to 200 ° C., preferably 50 ° C. to 170 ° C.

[Step (3)]
In this step, after the exposure in the step (2), development is performed using a negative developer containing 80% by mass or more of an organic solvent to form a resist pattern. The negative developer is a developer that selectively dissolves and removes the low-exposed portion and the unexposed portion. The organic solvent used as the negative developer is at least one selected from the group consisting of alcohol solvents, ether solvents, ketone organic solvents, amide solvents, ester organic solvents, and hydrocarbon solvents. Is preferred.

Examples of the alcohol solvent 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 -Monoalcohol solvents such as heptadecyl 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 alcohol solvents 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 solvents such as dipropylene glycol monopropyl ether.

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

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

Examples of amide solvents include N, N′-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, Examples thereof include N-methylpropionamide and N-methylpyrrolidone.

Examples of ester solvents include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, iso-propyl acetate, acetic acid-butyl, isopropyl acetate, amyl acetate, iso acetate -Butyl, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, n-acetate -Nonyl, methyl acetoacetate, ethyl acetoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl acetate Ether ether, diethylene glycol 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, lactic acid Examples thereof include n-amyl, diethyl malonate, dimethyl phthalate, and diethyl phthalate.

Examples of hydrocarbon solvents include n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane , Aliphatic hydrocarbon solvents 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 hydrocarbon solvents and the like.

Of these, methyl amyl ketone, butyl acetate, isopropyl acetate and amyl acetate are preferred. These organic solvents may be used alone or in combination of two or more.

The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 85% by mass or more, and still more preferably 90% by mass or more. By setting the organic solvent contained in the developer within the above range, the unexposed portion can be effectively dissolved and removed, and a resist pattern having excellent development characteristics and lithography characteristics can be formed. Examples of components other than the organic solvent include water and silicone oil.

An appropriate amount of a surfactant can be added to the developer as necessary. As the surfactant, for example, an ionic or nonionic fluorine-based and / or silicon-based surfactant can be used.

As a developing method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is left stationary for a certain time (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.

In the resist pattern forming method, the resist film may be washed with a rinse solution after the development in the step (3). Moreover, an organic solvent can be used also as the rinse liquid in the rinse process, and the generated scum can be efficiently washed. As the rinsing liquid, hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents and the like are preferable. Of these, alcohol solvents and ester solvents are preferable, and monovalent alcohol solvents having 6 to 8 carbon atoms are more preferable. Examples of the monohydric alcohol having 6 to 8 carbon atoms include linear, branched or cyclic monohydric alcohols such as 1-hexanol, 1-heptanol, 1-octanol, and 4-methyl-2-pen. Examples include butanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, and benzyl alcohol. Of these, 1-hexanol, 2-hexanol, 2-heptanol, and 4-methyl-2-pentanol are preferable.

Each component of the rinse liquid may be used alone or in combination of two or more. The water content in the rinse liquid is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less. By setting the water content to 10% by mass or less, good development characteristics can be obtained. In addition, the surfactant mentioned later can be added to the rinse liquid.

As a cleaning method, for example, a method of continuously applying a rinse liquid onto a substrate rotating at a constant speed (rotary coating method), a method of immersing the substrate in a tank filled with the rinse liquid for a predetermined time (dip method) ), A method (spray method) of spraying a rinse liquid on the substrate surface, and the like.

<Radiation sensitive resin composition>
The radiation sensitive resin composition used in the present invention contains a [A] polymer, a [B] acid generator, and a [C] polymer. The polymer [A] has an acid dissociable group, and the polarity of the polymer [A] is increased by the dissociation of the acid dissociable group by the action of the acid generated from the [B] acid generator. [B] The acid generator includes a cation and an anion having an alicyclic group, and the atomic number ratio (F / C) of the fluorine atom to the carbon atom of the anion is 0.1 or more and 0.5 or less. Therefore, it is uniformly dispersed without being unevenly distributed on the resist film surface and has an alicyclic group, so that the compatibility with the [A] polymer is good. The [C] polymer contains fluorine atoms, has a higher fluorine atom content than the [A] polymer, and is unevenly distributed on the resist film surface, so that it can impart water repellency and is suitable for immersion exposure. Contributes to film formation. Moreover, the said composition may contain arbitrary components in the range which does not impair the effect of this invention. Hereinafter, each component will be described in detail.

<[A] polymer>
[A] The polymer is a base polymer containing a structural unit having an acid-dissociable group and increasing in polarity when the acid-dissociable group is dissociated by the action of an acid. The base polymer refers to a polymer that is a main component among the polymers constituting the resist pattern formed from the radiation-sensitive resin composition, and preferably the total polymer constituting the resist pattern. A polymer occupying 50% by mass or more. The “acid-dissociable group” is a group that substitutes a hydrogen atom in a polar functional group such as a carboxyl group, and means a group that is dissociated by the action of an acid generated from an acid generator [B] upon exposure. To do. [A] Specific acid dissociable groups possessed by the polymer include groups represented by the following general formula (7).

[Structural unit (I)]
[A] Examples of the structural unit having an acid dissociable group of the polymer include the structural unit (I) represented by the following formula (6).

(In the formula (6), R ² is a hydrogen atom, a methyl group or a trifluoromethyl group .R ^p represents an acid dissociable group.)

The acid dissociable group represented by R ^p is preferably a group represented by the following formula (7).

(In the formula (7), R ^p1 , R ^p2 and R ^p3 are each an alkyl group having 1 to 4 carbon atoms, a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or a monovalent group having 4 to 20 carbon atoms. R ^p2 and R ^p3 may be bonded to each other to form a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atom to which they are bonded.)

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and 2-methylpropyl. Group, 1-methylpropyl group, t-butyl group and the like.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include polycyclic alicyclic rings having a bridged skeleton such as an adamantane skeleton and a norbornane skeleton. A formula group;
And monocyclic alicyclic groups having a cycloalkane skeleton such as cyclopentane and cyclohexane. These groups may be substituted with one or more of linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, for example.

Examples of the monovalent heterocyclic group having 4 to 20 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include groups represented by the following formulae. In the following formulae, n represents an integer of 0 to 3, and X represents an oxygen atom or a methylene group.

In the above formula (7), R ^p1 is an alkyl group having 1 to 4 carbon atoms, R ^p2 and R ^p3 are bonded to each other and have an adamantane skeleton or a cycloalkane skeleton together with the carbon atoms to which they are bonded. It is preferable to form a divalent group.

Examples of the structural unit (I) include structural units represented by the following formulas (6-1) to (6-4).

(In the formula (6-1) ~ (6-4), R 2 is ^.R ^{p1, R p2} and ^{R p3} as defined in the above formula (6) has the same meaning as the above formula (7) .n _p is (It is an integer from 1 to 4.)

Examples of the structural unit represented by the above formula (6) or (6-1) to (6-4) include a structural unit represented by the following formula.

(Wherein R ² has the same meaning as in the above formula (6))

In the [A] polymer, the content of the structural unit (I) is preferably such that the total amount of the structural unit (I) with respect to all the structural units constituting the [A] polymer exceeds 10 mol%, More preferably, it is 60 mol%. In addition, the [A] polymer may have 1 type, or 2 or more types of structural units (I).

[Structural unit (II)]
[A] The polymer preferably has a structural unit (II) having a lactone structure and / or a cyclic carbonate structure. By having such a structural unit (II), the adhesion of the resist film to the substrate can be improved. Here, the lactone structure represents a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The lactone ring is counted as the first ring, and when it is only the lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.

As structural unit (II) which has a lactone structure, the structural unit represented by a following formula is mentioned, for example.

(In the formula, R ^L1 represents a hydrogen atom, a methyl group or a trifluoromethyl group.)

Examples of the monomer that generates the structural unit (II) containing a lactone structure include compounds represented by the following formula (L-1).

(In the formula (L-1), R ^L1 is a hydrogen atom, a methyl group or a trifluoromethyl group. R ^L2 is a single bond or a divalent linking group. R ^L3 is a monovalent organic compound having a lactone structure. Group.)

Examples of the divalent linking group represented by R ^L2 include a divalent linear or branched hydrocarbon group having 1 to 20 carbon atoms.

Examples of the monovalent organic group having a lactone structure represented by R ^L3 include groups represented by the following formulas (L3-1) to (L3-6).

(In the formulas (L3-1) to (L3-6), R ^Lc1 is an oxygen atom or a methylene group. R ^Lc2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. N _Lc1 is 0 or 1. N _Lc2 is an integer of 0 to 3. * represents a bond that binds to R ^L2 in the above formula (L-1), and is represented by formulas (L3-1) to (L3-6). The group to be substituted may have a substituent.)

Examples of a preferable monomer that gives the structural unit (II) having the lactone structure include monomers described in paragraph [0043] of International Publication No. 2007/116664.

Moreover, as structural unit (II) which has a cyclic carbonate structure, the structural unit represented by a following formula is mentioned, for example. In the above formula, R ^C1 is a hydrogen atom or a methyl group.

In the [A] polymer, the content of the structural unit (II) is preferably such that the total amount of the structural unit (II) with respect to all the structural units constituting the [A] polymer exceeds 10 mol%, More preferably, it is 60 mol%. [A] The polymer may have one or more structural units (II).

[A] The polymer may contain other structural units other than the above structural units (I) and / or (II).

[Other structural units]
Examples of the structural unit other than the structural unit (I) and / or (II) include, for example, adamantane-1-yl (meth) acrylate, 3-methyladamantan-1-yl (meth) acrylate, and (meth) acrylic. 3-ethyladamantan-1-yl (meth) acrylate, 3-hydroxyadamantan-1-yl (meth) acrylate, 3,5-dihydroxyadamantan-1-yl (meth) acrylate, 3-cyanoadamantane (meth) acrylate 1-yl, 3-carboxyadamantan-1-yl (meth) acrylate, 3,5-dicarboxyadamantan-1-yl (meth) acrylate, 3-carboxy-5-hydroxyadamantane-1 (meth) acrylate -Due to monomers such as yl, 3-methoxycarbonyl-5-hydroxyadamantan-1-yl (meth) acrylate Structural units which can be mentioned.

As content of [A] polymer contained in solid content (component except a solvent) of the radiation sensitive resin composition used for this invention, 50 mass% or more is preferable, 80 mass% or more is more preferable, 85 mass% or more is still more preferable. [A] By making the content of the polymer in the above range, the resist pattern formability can be further improved.

<[A] Polymer Synthesis Method>
[A] The polymer can be produced, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable solvent using a radical polymerization initiator. As such a synthesis method, for example, a solution containing a monomer and a radical initiator is dropped into a reaction solvent or a solution containing the monomer to cause a polymerization reaction, and a solution containing the monomer and In addition, there may be mentioned a method in which a solution containing a radical initiator is dropped into a solution containing a reaction solvent or a monomer separately to cause a polymerization reaction.

Examples of the radical initiator used in the polymerization include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2 -Cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile) and the like. These initiators may be used alone or in combination of two or more.

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. These solvents may be used alone or in combination of two or more.

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

[A] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 1,000 to 100,000, more preferably 1,000 to 50,000, and 1,000. ˜30,000 is particularly preferred. [A] By making Mw of a polymer into the said range, it has the solubility to a resist solvent sufficient to use as a resist, and dry etching resistance and a resist pattern cross-sectional shape become favorable.

[A] The ratio (Mw / Mn) of the Mw of the polymer to the number average molecular weight (Mn) in terms of polystyrene by GPC method is usually 1 to 3, preferably 1 to 2.

<[B] Acid generator>
[B] The acid generator generates an acid upon exposure, and the acid dissociable groups present in the [A] polymer are dissociated by the acid. As a result, the polymer [A] becomes hardly soluble in a developer containing an organic solvent. The content of the [B] acid generator in the composition is a compound as described below (hereinafter sometimes referred to as “[B] acid generator” as appropriate), and the anion or cation is a polymer. It may be in the form incorporated as part or a mixture of both forms.

The [B] acid generator used in the present invention contains a cation and an anion having an alicyclic group, and the atomic ratio (F / C) of fluorine atom to carbon atom of this anion is 0.1 or more and 0.00. 5 or less. [B] Since the anion of the acid generator has an alicyclic group, the [B] acid generator is excellent in compatibility with the resin and suitability as a composition. Moreover, when the atomic ratio (F / C) of fluorine atoms and carbon atoms contained in the anion is 0.1 or more and 0.5 or less, the [B] acid generator is unevenly distributed in the vicinity of the resist film surface. Evenly distributed without any problems. In this way, the [B] acid generator is uniformly dispersed in the resist film, so that excessive generation of acid on the resist film surface is suppressed, and the polymer deprotects specifically on the outermost surface of the resist coating film. As a result, the occurrence of missing contact holes can be prevented.

[B] Examples of the cation contained in the acid generator include a sulfonium cation, a thiophenium cation, an ammonium cation, a phosphonium cation, an iodonium cation, and a pyridinium cation. Of these cations, a sulfonium cation and a thiophenium cation are preferable, a cation represented by the following formula (B-pc) is more preferable, and a triphenylsulfonium cation is particularly preferable.

(In the formula (B-pc), R ^pc1 represents a hydrogen atom, a fluorine atom, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, or an alkoxycarbonyl group having 2 to 11 carbon atoms. R ^pc2 is an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, or an alkanesulfonyl group having 1 to 10 carbon atoms, and R ^pc3 is independently an alkyl group having 1 to 10 carbon atoms, phenyl The two R ^pc3 may be bonded to each other to form a divalent group having 2 to 10 carbon atoms, t represents an integer of 0 to 2, and r is Represents an integer of 0 to 10.)

[B] The anion contained in the acid generator has an alicyclic group, and the atomic ratio (F / C) between the fluorine atom and the carbon atom contained in the anion is 0.1 or more and 0.5 or less, Among these, (F / C) is preferably 0.1 or more and 0.4 or less, and more preferably 0.1 or more and 0.3 or less.

(In formula (1), R ¹ is a monovalent organic group containing a monocyclic or polycyclic alicyclic group. N is 1 or 2. R ^f1 and R ^f2 are each independently a hydrogen atom. , A fluorine atom or a fluorinated alkyl group having 1 to 4 carbon atoms, except when both R ^f1 and R ^f2 are hydrogen atoms, and when there are a plurality of R ^f1 and R ^f2 , a plurality of R ^f1 and R ^f2 may be the same or different.)

In the above formula (1), the monovalent organic group containing an alicyclic group represented by R ¹ is, for example, a monovalent containing a monocyclic alicyclic group having a cycloalkane skeleton such as cyclopentane or cyclohexane. Hydrocarbon groups of
And monovalent hydrocarbon groups including polycyclic alicyclic groups having a bridged skeleton such as an adamantane skeleton and a norbornane skeleton.

Examples of the monovalent hydrocarbon group include a chain hydrocarbon group having 1 to 10 carbon atoms such as methyl group, ethyl group, propyl group, i-propyl group, butyl group, pentyl group, hexyl group, and octyl group. A group in which at least one hydrogen atom is substituted with the alicyclic group can be exemplified.

In addition, 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.

In the above formula (1), examples of the fluorinated alkyl group having 1 to 4 carbon atoms include fluorinated methyl group, fluorinated ethyl group, fluorinated n-propyl group, fluorinated i-propyl group, and fluorinated n-butyl. Group, fluorinated t-butyl group and the like.

Examples of such anions include norbornane derivatives, adamantane derivatives, deoxycholic acid esters, lithocholic acid esters and the like in which the above (F / C) is 0.1 or more and 0.5 or less. It is done.

Among them, examples of the anion of the above [B] acid generator include those represented by the following formulas (2) to (5) and (8) to (25). Among these, the following formula (2) ) To (5) are more preferred. In the formula, “Me” represents a methyl group.

[B] The atomic ratio (F / C) of fluorine atom and carbon atom contained in the anion of the acid generator can be determined by measuring ¹³ C-NMR, ¹ H-NMR, and IR spectrum.

In addition, it is preferable that the anion does not contain an aromatic group. By not containing an aromatic group in the anion, the ArF laser transmittance in the resist coating is improved, and the ArF laser is uniformly irradiated from the resist film surface to the vicinity of the resist substrate, thereby improving the rectangularity of the resist pattern. To do.

[B] Specific examples of the acid generator include
Examples of the sulfonium salt include triphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1]. Hept-2-yl-1,1-difluoroethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4- Methanesulfonylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) -hexane-1-sulfonate and Etc. triphenylsulfonium 2-adamantyl-1,1-difluoroethane sulfonates. Of these, triphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept -2-yl-1,1-difluoroethanesulfonate, triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) -hexane-1-sulfonate and triphenylsulfonium 2-adamantyl- 1,1-difluoroethanesulfonate is preferred.

Examples of tetrahydrothiophenium salts include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2- Tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethane Sulfonate and 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate Can be mentioned.

Examples of iodonium salts include diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate and bis (4-tert-butylphenyl) iodonium 2-bicyclo [ 2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate and the like.

These [B] acid generators may be used alone or in combination of two or more. In addition, known sulfonimide compounds, halogen-containing compounds, diazoketone compounds and the like can be used in combination as other acid generators.

The content of the [B] acid generator contained in the solid content (component excluding the solvent) of the radiation-sensitive resin composition used in the present invention is preferably 5% by mass or more and 10% by mass or less, and more preferably 8% by mass or more. 9 mass% or less is more preferable. [B] By setting the content of the acid generator within the above range, sufficient acid can be generated during exposure. In particular, the amount used when [B] the acid generator is an acid generator is usually from 0 to 100 parts by mass of the [A] polymer from the viewpoint of ensuring the sensitivity and developability as a resist. 1 to 15 parts by mass is preferable, 3 to 15 parts by mass is more preferable, and 5 to 12 parts by mass is further preferable. In this case, if the amount of the [B] acid generator used is less than 0.1 parts by mass, the sensitivity and developability tend to be reduced. On the other hand, if it exceeds 15 parts by mass, the transparency to radiation is reduced and desired. It tends to be difficult to obtain a resist pattern.

<[C] polymer>
The [C] polymer is a polymer having a higher fluorine atom content than the [A] polymer. The radiation-sensitive resin composition used in the resist pattern forming method contains the [C] polymer, so that when the resist film is formed, the water-repellent characteristics of the [C] polymer in the film The distribution tends to be unevenly distributed near the resist film surface. For this reason, it is preferable that an acid generator, an acid diffusion controller, and the like are prevented from being eluted into the immersion medium during immersion exposure. Further, due to the water-repellent characteristics of the [C] polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Further, the receding contact angle between the resist film and the immersion medium is increased, and no water droplets remain, and high-speed scanning exposure is possible. Here, the [C] polymer is not particularly limited as long as it has the above properties, but preferably has a fluorinated alkyl group. When the polymer [C] has a fluorinated alkyl group in the structure, the above characteristics are further improved.

The [C] polymer in the present invention is formed by polymerizing one or more monomers containing fluorine in the structure. Examples of the monomer containing fluorine in the structure include those containing a fluorine atom in the main chain, those containing a fluorine atom in the side chain, and those containing a fluorine atom in the main chain and the side chain.

Examples of monomers containing fluorine atoms in the main chain include α-fluoroacrylate compounds, α-trifluoromethyl acrylate compounds, β-fluoroacrylate compounds, β-trifluoromethyl acrylate compounds, α, β-fluoroacrylate compounds. , Α, β-trifluoromethyl acrylate compounds, compounds in which one or more kinds of vinyl moiety hydrogen are substituted with fluorine or a trifluoromethyl group, and the like.

Examples of the monomer containing a fluorine atom in the side chain include those in which the side chain of an alicyclic olefin compound such as norbornene is fluorine or a fluoroalkyl group or a derivative thereof, or a fluoroalkyl of acrylic acid or methacrylic acid. And an ester compound of a group or a derivative thereof, and one or more olefin side chains (parts not including a double bond) are fluorine or a fluoroalkyl group or a derivative thereof.

Furthermore, examples of the monomer containing a fluorine atom in the main chain and the side chain include α-fluoroacrylic acid, β-fluoroacrylic acid, α, β-fluoroacrylic acid, α-trifluoromethylacrylic acid, β- An ester compound of a fluoroalkyl group such as trifluoromethylacrylic acid or α, β-trifluoromethylacrylic acid or a derivative thereof, or a compound in which one or more types of vinyl moiety hydrogen is substituted with fluorine or a trifluoromethyl group The chain is substituted with a fluorine or fluoroalkyl group or a derivative thereof, the hydrogen bonded to the double bond of one or more alicyclic olefin compounds is substituted with a fluorine atom or a trifluoromethyl group, and the side chain In which is a fluoroalkyl group or a derivative thereof. In addition, the alicyclic olefin compound here represents a compound in which a part of the ring is a double bond.

In the present invention, the structural unit for imparting fluorine to the [C] polymer is not particularly limited as described above, but is a structural unit represented by the following formula (21) (hereinafter referred to as “structural unit (1)”). Is preferably used.

In the above formula (21), R ³ represents hydrogen, a methyl group or a trifluoromethyl group. A represents a linking group, R ⁴ represents a linear or branched alkyl group having 1 to 6 carbon atoms and a monovalent alicyclic carbon atom having 4 to 20 carbon atoms, containing at least one fluorine atom. A hydrogen group or a derivative group thereof;

A in the formula (21) represents a linking group, and examples thereof include a single bond, an oxygen atom, a sulfur atom, a carbonyloxy group, an oxycarbonyl group, an amide group, a sulfonylamide group, and a urethane group.

Preferred monomers that give the structural unit (1) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, and perfluoroethyl (meth) acrylate. Perfluoro n-propyl (meth) acrylate, perfluoro i-propyl (meth) acrylate, perfluoro n-butyl (meth) acrylate, perfluoro i-butyl (meth) acrylate, perfluoro Fluoro t-butyl (meth) acrylic acid ester, 2- (1,1,1,3,3,3-hexafluoropropyl) (meth) acrylic acid ester, 1- (2,2,3,3,4, 4,5,5-octafluoropentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) Acrylic acid ester, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, 1- (3,3,4,4,5,5,6,6,7,7 , 8,8,9,9,10,10,10-heptadecafluorodecyl) (meth) acrylic acid ester, 1- (5-trifluoromethyl-3,3,4,4,5,6,6, 6-octafluorohexyl) (meth) acrylic acid ester, 2-trifluoromethyl-2-hydroxy-1,1,1-trifluoro-4-pentyl (meth) acrylic acid ester and the like.

The above [C] polymer may contain only one type of the structural unit (1), or may contain two or more types. The content of the structural unit (1) is usually 5 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more when the total structural unit in the [C] polymer is 100 mol%. is there. If the content of the structural unit (1) is less than 5 mol%, a receding contact angle of 70 degrees or more may not be achieved, and elution of an acid generator or the like from the resist film may not be suppressed.

[C] In addition to the above-mentioned structural unit containing fluorine in the structure, the polymer includes, for example, a structural unit having an acid-dissociable group for controlling the dissolution rate in a developer, a lactone skeleton, a hydroxyl group, and a carboxyl. One or more “other structural units” such as a structural unit having a group, a structural unit having an alicyclic compound, or a structural unit derived from an aromatic compound for suppressing light scattering due to reflection from a substrate are contained. be able to.

Among the other structural units, those having an acid-dissociable group can be the same as the structural unit (I) of the polymer [A] (hereinafter referred to as “structural unit (2)”). ).

Examples of such structural unit (2) include (meth) acrylic acid 2-methyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyladamantyl-2-yl ester, and (meth) acrylic acid-2. -Methylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-2-ethylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid 1- (bicyclo [2.2.1] Hept-2-yl) -1-methyl ethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methyl ethyl ester, (meth) acrylic acid 1-methyl- 1-cyclopentyl ester, 1-ethyl-1-cyclopentyl ester of (meth) acrylic acid, 1-methyl-1-cyclohexyl ester of (meth) acrylic acid, (meth ) Acrylic acid 1-ethyl-1-cyclohexyl ester, and the like are preferable.

As the compound containing a lactone skeleton, for example, the same unit as the structural unit (II) of the polymer [A] can be used (hereinafter referred to as “structural unit (3)”).

As what contains an alicyclic compound, the structural unit represented by following formula (22) etc. can be mentioned, for example (henceforth "structural unit (4)").

In the above formula (22), R ⁵ represents a hydrogen atom, a methyl group, or a trifluoromethyl group, and Y is an alicyclic hydrocarbon group having 4 to 20 carbon atoms.

Examples of the alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by Y in the above formula (22) include cyclobutane, cyclopentane, cyclohexane, bicyclo [2.2.1] heptane, and bicyclo [2.2. .2] octane, tricyclo [5.2.1.02,6] decane, tetracyclo [6.2.13,6.02,7] dodecane, tricyclo [3.3.1.13,7] decane And hydrocarbon groups composed of alicyclic rings derived from cycloalkanes such as These cycloalkane-derived alicyclic rings may have a substituent, and examples of the substituent include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, 2- The alkyl group may be substituted with one or more linear, branched or cyclic alkyl groups having 1 to 4 carbon atoms such as a methylpropyl group, 1-methylpropyl group, and t-butyl group. These are not limited to those substituted with these alkyl groups, but may be those substituted with a hydroxyl group, a cyano group, a hydroxyalkyl group having 1 to 10 carbon atoms, a carboxyl group, or oxygen.

Preferred monomers giving the structural unit (4) include (meth) acrylic acid-bicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-bicyclo [2.2.2] octa -2-yl ester, (meth) acrylic acid-tricyclo [5.2.1.02,6] dec-7-yl ester, (meth) acrylic acid-tetracyclo [6.2.1.13, 6.02 , 7] dodeca-9-yl ester, (meth) acrylic acid-tricyclo [3.3.1.13,7] dec-1-yl ester, (meth) acrylic acid-tricyclo [3.3.1.13. , 7] Dec-2-yl ester and the like.

Further, examples of a preferable monomer that generates an aromatic compound (hereinafter referred to as “structural unit (5)”) include, for example, styrene, α-methylstyrene, 2-methylstyrene, and 3-methylstyrene. 4-methylstyrene, 2-methoxystyrene, 3-methoxystyrene, 4-methoxystyrene, 4- (2-t-butoxycarbonylethyloxy) styrene 2-hydroxystyrene, 3-hydroxystyrene, 4-hydroxystyrene, 2 -Hydroxy-α-methylstyrene, 3-hydroxy-α-methylstyrene, 4-hydroxy-α-methylstyrene, 2-methyl-3-hydroxystyrene, 4-methyl-3-hydroxystyrene, 5-methyl-3- Hydroxystyrene, 2-methyl-4-hydroxystyrene, 3-methyl-4-hydride Xylstyrene, 3,4-dihydroxystyrene, 2,4,6-trihydroxystyrene, 4-t-butoxystyrene, 4-t-butoxy-α-methylstyrene, 4- (2-ethyl-2-propoxy) styrene, 4- (2-ethyl-2-propoxy) -α-methylstyrene, 4- (1-ethoxyethoxy) styrene, 4- (1-ethoxyethoxy) -α-methylstyrene, phenyl (meth) acrylate, (meta ) Benzyl acrylate, acenaphthylene, 5-hydroxyacenaphthylene, 1-vinylnaphthalene, 2-vinylnaphthalene, 2-hydroxy-6-vinylnaphthalene, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, 1 -Naphthylmethyl (meth) acrylate, 1-anthryl (meth) acrylate, 2-an Examples include tolyl (meth) acrylate, 9-anthryl (meth) acrylate, 9-anthrylmethyl (meth) acrylate, and 1-vinylpyrene.

In the [C] polymer in the present invention, only one type of “other structural units” represented by the structural unit (2), the structural unit (3), the structural unit (4), and the structural unit (5) is contained. Or two or more of them may be contained. The content of these other structural units is usually 80 mol% or less, preferably 75 mol% or less, more preferably 70 mol% or less, assuming that all the structural units in the [C] polymer are 100 mol%. .

[C] The polymer may contain structural units other than the structural units (1) to (5) as long as the effects of the present invention are not impaired.

The fluorine content (% by mass) of the [A] polymer and [C] polymer can be determined by measuring ¹³ C-NMR, ¹ H-NMR, and IR spectrum.

As content of [C] polymer contained in solid content (component except a solvent) of the radiation sensitive resin composition used for this invention, 1 to 10 mass% is preferable, and 1.5 mass% The content is more preferably 8% by mass or less and further preferably 2% by mass or more and 3% by mass or less. [C] By setting the content of the polymer in the above range, the resist pattern formability in immersion exposure can be further improved.

<[C] Polymer Synthesis Method>
[C] The polymer can be produced, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable solvent using a radical polymerization initiator.

Examples of the radical initiator and solvent used in the polymerization include the same radical initiator and solvent as those mentioned in the method for synthesizing [A] polymer.

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

The Mw of the [C] polymer is preferably 1,000 to 50,000, more preferably 1,000 to 30,000, and particularly preferably 1,000 to 10,000. [C] When the Mw of the polymer is less than 1,000, a sufficient advancing contact angle cannot be obtained. On the other hand, when Mw exceeds 50,000, the developability of the resist tends to decrease.

[C] The ratio of Mw to Mn (Mw / Mn) of the polymer is usually 1 to 3, and preferably 1 to 2.

<Optional component>
In addition to the [A] polymer, [B] acid generator, and [C] polymer, the composition can contain other optional components as long as the effects of the present invention are not impaired. Examples of other optional components include an acid diffusion controller, a solvent, an acid generator other than the [B] acid generator, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer.

[Acid diffusion controller]
The acid diffusion controller controls the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator by exposure, has the effect of suppressing undesirable chemical reactions in the non-exposed areas, and the resulting radiation sensitive resin composition The storage stability of the product is further improved, the resolution as a resist is further improved, and the line width of the resist pattern due to fluctuations in the holding time from exposure to development processing can be suppressed, and the process stability is extremely excellent. A composition is obtained. The inclusion form of the acid diffusion controller in the composition may be in the form of a free compound, incorporated as part of the polymer, or both forms.

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, , 4-bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, bis (2-dimethylaminoethyl) ) Ether, bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxalinol, N, N, N ′, N′-tetrakis (2-hydroxypropyl) And ethylenediamine, N, N, N ′, N ″ N ″ -pentamethyldiethylenetriamine and the like.

Examples of the amide group-containing compound include Nt-butoxycarbonyl group-containing amino compounds such as Nt-butoxycarbonyl-4-hydroxypiperidine, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N -Methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, N-acetyl-1-adamantylamine, isocyanuric acid tris (2-hydroxyethyl) and the like.

Examples of urea compounds include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tri-n-butylthiourea, etc. Is mentioned.

Examples of the nitrogen-containing heterocyclic compound include imidazoles; pyridines; piperazines; pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, Nt-butoxycarbonylpyrrolidine, piperidine, piperidineethanol, 3-piperidino-1, 2-propanediol, morpholine, 4-methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine, 3- (N-morpholino) -1,2-propanediol, N-cyclohexylcarbonyloxyethylmorpholine, 1 , 4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] octane, and the like.

Further, as the acid diffusion controlling agent, a photodegradable base that generates a weak acid by exposure can also be used. As an example of the photodegradable base, there is an onium salt compound that is decomposed by exposure and loses acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (23) and an iodonium salt compound represented by the following formula (24). Of these, triphenylsulfonium salicylate is preferable.

(In Formula (23) and Formula (24), R ⁶ to R ¹⁰ are each independently a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, or a halogen atom. Also, Formula (23) and Formula (24 Z ⁻ is OH ⁻ , R ¹¹ —COO ⁻ , R ¹¹ —SO ₃ ^— or an anion represented by the following formula (25), provided that R ¹¹ is an alkyl group, an aryl group, or an alkaryl group. is there.)

(In the formula (25), R ¹² represents a linear or branched alkyl group having 1 to 12 carbon atoms, in which some or all of hydrogen atoms may be substituted with fluorine atoms, or a group having 1 to 12 carbon atoms. A straight or branched alkoxyl group, u is an integer of 0 to 2)

These acid diffusion control agents may be used alone or in combination of two or more. As content of an acid diffusion control agent, less than 5 mass parts is preferable with respect to 100 mass parts of [A] polymers. When the total amount used exceeds 5 parts by mass, the sensitivity as a resist tends to decrease.

[solvent]
The composition usually contains a solvent. The solvent is not particularly limited as long as it can dissolve at least the above-mentioned [A] polymer, [B] acid generator, [C] polymer and optional components added as necessary. Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and mixed solvents thereof.

Specific examples of the solvent include the same organic solvents listed above. Of these, propylene glycol monomethyl ether acetate and cyclohexanone are preferred. These solvents may be used alone or in combination of two or more.

[[B] Acid generator other than acid generator]
The composition may contain an acid generator other than the [B] acid generator as long as the effects of the present invention are not impaired. Examples of such an acid generator include onium salt compounds other than [B] acid generators, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, and the like.

Examples of the onium salt compounds include sulfonium salts (including tetrahydrothiophenium salts), iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like.

Examples of the sulfonium salt include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium camphorsulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate. 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium camphorsulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate , 4-methanesulfonyl-phenyl diphenyl sulfonium nonafluoro -n- butane sulfonate, 4-methanesulfonyl-phenyl diphenyl sulfonium perfluoro -n- octane sulfonate, and 4-methanesulfonyl-phenyl camphorsulfonate and the like.

Examples of the tetrahydrothiophenium salt include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate and 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium. Nonafluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothio Phenium camphorsulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n- Butanesulfone 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium camphorsulfonate, -(3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- ( 3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium camphorsulfonate, and the like.

Examples of the iodonium salt include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium camphorsulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate. Bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium camphorsulfonate, etc. Is mentioned.

Examples of the sulfonimide compound include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy) bicyclo [ 2.2.1] Hept-5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3- Dicarboximide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene -2,3-dicarboximide, N- (2- (3-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dodecanyl) -1,1-difluoroethanesulfonyl Oxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-di Carboximide etc. can be mentioned. One or more of these other acid generators can be used in combination.

[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 In addition to nonionic surfactants such as distearate, KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, EF352 (above, Tochem Products), MegaFuck F171, F173 (above, Dainippon Ink and Chemicals), Florard FC430, FC431 ( Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Industry) Company). These surfactants may be used alone or in combination of two or more.

[Alicyclic skeleton-containing compound]
The alicyclic skeleton-containing compound has the effect of improving dry etching resistance, resist pattern shape, adhesion to the substrate, and the like.

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholic acid, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as tert-butyl lithocholic acid, tert-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like. These alicyclic skeleton containing compounds may be used independently and may use 2 or more types together.

[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 composition.

Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines, and the like. These sensitizers may be used alone or in combination of two or more.

<Preparation of radiation-sensitive resin composition>
The composition can be prepared, for example, by mixing [A] polymer, [B] acid generator, [C] polymer and other optional components in a predetermined ratio in an organic solvent. In addition, the composition can be prepared and used in a state dissolved or dispersed in a suitable organic solvent.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified.

The weight average molecular weight (Mw) and the number average molecular weight (Mn) were determined by gel permeation chromatography (GPC) under the following conditions using GPC columns (Tosoh Corporation, 2 G2000HXL, 1 G3000HXL, 1 G4000HXL). Monodispersed polystyrene was measured as a standard substance.
Column temperature: 40 ° C
Elution solvent: Tetrahydrofuran (Wako Pure Chemical Industries, Ltd.)
Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer

¹ H-NMR analysis and ¹³ C-NMR analysis were measured using a nuclear magnetic resonance apparatus (JEOL Ltd., JNM-EX270).

The [A] polymer, [B] acid generator, [C] polymer, acid diffusion controller and solvent used in the preparation of the composition are as follows.

The monomers used for the synthesis of the following [A] polymer and the later-described [C] polymer are shown below.

<[A] Synthesis of polymer>
[A] As the polymer, the following polymers (A-1) to (A-8) were used.

[Synthesis Example 1]
<Polymer (A-1)>
12.93 g (50 mol%) of monomer (M-1) represented by the above formula and 17.07 g (50 mol%) of monomer (M-8) were dissolved in 60 g of 2-butanone, and further azobis A solution charged with 0.50 g of isobutyronitrile was prepared. Next, a 200 mL three-necked flask charged with 30 g of 2-butanone was purged with nitrogen for 30 minutes, and then the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added using a dropping funnel. The solution was added dropwise over 3 hours. The polymerization reaction was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution was cooled with water, cooled to 30 ° C. or lower, poured into 600 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 150 g of methanol in the form of a slurry, then filtered again and dried at 50 ° C. for 17 hours to obtain a white powder polymer (A-1) (Mw = 13,000, Mw / Mn = 1.5, yield = 85%). The proportion of structural units derived from (M-1) / (M-8) in the polymer (A-1) was 50/50 (mol%).

[Synthesis Example 2]
<Polymer (A-2)>
As shown in Table 1 below, Synthesis Example 1 was used except that monomer (M-2), monomer (M-3) and monomer (M-8) were used as shown in Table 1 below. In the same manner as above, a polymer (A-2) was obtained (Mw = 7,000, Mw / Mn = 1.4, yield = 83%). The proportion of structural units derived from (M-2) / (M-3) / (M-8) in the polymer (A-2) was 15/35/50 (mol%).

[Synthesis Example 3]
<Polymer (A-3)>
As shown in Table 1 below, the synthesis examples described above except that the monomer (M-3), the monomer (M-6) and the monomer (M-8) were used as monomers. 1 was obtained in the same manner as in Example 1 to obtain a polymer (A-3) (Mw = 6,000, Mw / Mn = 1.4, yield = 87%). The ratio of structural units derived from (M-3) / (M-6) / (M-8) in the polymer (A-3) was 60/20/20 (mol%).

[Synthesis Example 4]
<Polymer (A-4)>
As shown in Table 1 below, the above synthesis examples except that the above monomer (M-3), monomer (M-7) and monomer (M-12) were used as monomers. 1 to give a polymer (A-4) (Mw = 7,000, Mw / Mn = 1.4, yield = 85%). The ratio of structural units derived from (M-3) / (M-7) / (M-12) in the polymer (A-4) was 40/30/30 (mol%).

[Synthesis Example 5]
<Polymer (A-5)>
As shown in Table 1 below, the above synthesis examples except that the above monomer (M-2), monomer (M-7) and monomer (M-10) were used as monomers. The same operation as in Example 1 was performed to obtain a polymer (A-5) (Mw = 7,800, Mw / Mn = 1.6, yield = 80%). The proportion of structural units derived from (M-2) / (M-7) / (M-10) in the polymer (A-5) was 40/10/50 (mol%).

[Synthesis Example 6]
<Polymer (A-6)>
As shown in Table 1 below, the above synthesis examples except that the above monomer (M-3), monomer (M-7) and monomer (M-11) were used as monomers. The same operation as in Example 1 was performed to obtain a polymer (A-6) (Mw = 8,200, Mw / Mn = 1.6, yield = 81%). The proportion of structural units derived from (M-3) / (M-7) / (M-11) in the polymer (A-6) was 40/30/30 (mol%).

[Synthesis Example 7]
<Polymer (A-7)>
As shown in Table 1 below, the above synthesis examples except that the above monomer (M-4), monomer (M-7) and monomer (M-9) were used as monomers. 1 to give a polymer (A-7) (Mw = 7,900, Mw / Mn = 1.5, yield = 80%). The ratio of structural units derived from (M-4) / (M-7) / (M-9) in the polymer (A-7) was 30/25/45 (mol%).

[Synthesis Example 8]
<Polymer (A-8)>
As shown in Table 1 below, the above synthesis examples except that the above monomer (M-5), monomer (M-7) and monomer (M-12) were used as monomers. 1 to give a polymer (A-8) (Mw = 7,300, Mw / Mn = 1.5, yield = 78%). The proportion of structural units derived from (M-5) / (M-7) / (M-12) in the polymer (A-8) was 30/25/45 (mol%).

<[B] Acid generator>
[B] The following (B-1) to (B-7) were used as acid generators.

(B-1): Triphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate represented by the following formula

(B-2): Triphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1-difluoroethanesulfonate represented by the following formula

(B-3): Triphenylsulfonium 2-adamantyl-1,1-difluoroethanesulfonate represented by the following formula

(B-4): Triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) -hexane-1-sulfonate represented by the following formula

(B-5): Triphenylsulfonium 1,1,2,2,3,3,4,4,4-nonafluorobutanesulfonate represented by the following formula

(B-6): Triphenylsulfonium 2-cyclohexylmethyloxycarbonyl-1,1,1,3,3,3-hexafluoropropane-2-sulfonate represented by the following formula

(B-7): Triphenylsulfonium camphorsulfonate represented by the following formula

<Synthesis of [C] polymer>
As the [C] polymer, the following polymer (C-1) and polymer (C-2) were used.

[Synthesis Example 9]
<Polymer (C-1)>
21.50 g (70 mol%) of the monomer (M-2) represented by the above formula and 8.50 g (30 mol%) of the monomer (M-13) were dissolved in 60 g of 2-butanone, and A solution charged with 1.38 g of 2′-azobis (isobutyronitrile) was prepared. Next, a 200 mL three-necked flask charged with 30 g of 2-butanone was purged with nitrogen for 30 minutes, and then the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added 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, the solution was cooled with water, cooled to 30 ° C. or lower, poured into 600 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 150 g of methanol in the form of a slurry, then filtered again and dried at 50 ° C. for 12 hours to obtain a white powder polymer (C-1) (Mw = 7,500, Mw / Mn = 1.4, yield = 89%). The ratio of structural units derived from (M-2) / (M-13) in the polymer (C-1) was 70/30 (mol%).

[Synthesis Example 10]
<Polymer (C-2)>
As shown in Table 2 below, the above synthesis examples except that the above monomer (M-2), monomer (M-14) and monomer (M-15) were used as monomers. The same operation as in No. 9 was performed to obtain a polymer (C-2) (Mw = 6,500, Mw / Mn = 1.5, yield = 82%). The proportion of structural units derived from (M-2) / (M-14) / (M-15) in the polymer (C-2) was 50/40/10 (mol%).

<Acid diffusion control agent>
Examples of the acid diffusion controller include (D-1) Nt-butoxycarbonyl-4-hydroxypiperidine, (D-2) triphenylsulfonium salicylate, and (D-3) N-cyclohexylcarbonyloxyethylmorpholine. Was used.

<Solvent>
The following (E-1) and (E-2) were used as the solvent.
E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone

[Example 1]
<Preparation of radiation-sensitive resin composition>
Polymer (A-1) 100 parts by mass, (B-1) 9.5 parts by mass, Polymer (C-1) 3 parts by mass, (D-1) 0.94 parts by mass, (E-1) 2 010 parts by mass and (E-2) 860 parts by mass were mixed to obtain a uniform solution. Then, the radiation sensitive resin composition (henceforth, composition 1) was prepared by filtering using a membrane filter with a hole diameter of 200 nm. The total solid content was 5% by mass.

[Examples 2 to 19]
[A] A radiation-sensitive resin composition (hereinafter, referred to as “Example 1”) except that the types and blending amounts of the polymer, [B] acid generator, and acid diffusion controller were changed to Table 3 below. Compositions 2 to 19) were prepared.

[Comparative Examples 1 to 6]
[A] A radiation-sensitive resin composition (hereinafter, referred to as “Example 1”) except that the types and blending amounts of the polymer, [B] acid generator, and acid diffusion controller were changed to Table 3 below. Compositions 20-25) were prepared.

[Example 20]
<Resist pattern formation>
An antireflection film forming agent (Burewer Science, trade name “ARC66”) was spin-coated on a 12-inch silicon wafer using “CLEAN TRACK Lithius Pro i” (Tokyo Electron), and then at 205 ° C. Pre-baking (PB) was performed for 60 seconds to form a lower antireflection film having a thickness of 105 nm. The composition 1 obtained above was spin-coated on this substrate using “CLEAN TRACK Lithius Pro i” (manufactured by Tokyo Electron Ltd.), pre-baked (PB) at 90 ° C. for 60 seconds, and then at 30 ° C. for 30 seconds. A resist layer having a thickness of 100 nm was formed by cooling for 2 seconds. Next, using an ArF immersion exposure apparatus (trade name “NSR-S610C”, manufactured by Nikon Seiki Co., Ltd.), exposure was performed under the best focus condition with NA = 1.3 and quadropole optical conditions. Post exposure bake (PEB) at 105 ° C. for 60 seconds on a hot plate of the product name “CLEAN TRACK Lithius Pro i”, cooled at 23 ° C. for 30 seconds, and then paddle developed for 30 seconds with methyl amyl ketone as developer. And rinsed with 4-methyl-2-pentanol for 7 seconds. A resist pattern having a 48 nm hole / 96 nm pitch was formed by spin-drying at 2000 rpm for 15 seconds.

[Examples 21 to 38, Comparative Examples 7 to 12]
A resist pattern was formed in the same manner as in Example 20 except that the type of coating liquid, PB temperature, and PEB temperature were changed to the following Table 4. The evaluation results of the obtained resist pattern are also shown in Table 4.

<Evaluation>
[Sensitivity (mJ / cm ² )]
In the resist pattern formation, the exposure amount (mJ / cm ² ) was changed by 1 (mJ / cm ² ) from 10 to 40, and the size of the contact hole was measured. The exposure amount at which the target size was 48 nm was defined as sensitivity.

[Number of missing contact holes]
Evaluation was performed using each of the resist patterns obtained above. For the evaluation, a length measuring SEM “CG-4000” manufactured by Hitachi High Technologies was used. The missing contact hole was evaluated by setting the observation magnification to 50K and counting the number of missing contact holes observed in one field of view. The smaller the number of missing contact holes, the better.

As can be seen from the evaluation results in Table 4, the composition used in the resist pattern formation method of the present invention is excellent in sensitivity, and according to the resist pattern formation method using the composition of the present invention, the occurrence of missing contact holes It was found that a hole pattern with a good shape can be formed.

INDUSTRIAL APPLICABILITY The present invention can provide a resist pattern forming method and a radiation-sensitive resin composition that have excellent sensitivity and are less likely to cause missing contact holes when a developer containing an organic solvent is used, that is, have excellent lithography properties. .

Claims

(1) a resist film forming step of applying a radiation sensitive resin composition on a substrate;
(2) an exposure step, and (3) a resist pattern forming method including a step of developing using a developer containing 80% by mass or more of an organic solvent,
The radiation sensitive resin composition is
[A] a base polymer having an acid dissociable group,
[B] Generation of a radiation-sensitive acid containing a cation and an anion having an alicyclic group, wherein the ratio of the number of atoms (F / C) of fluorine and carbon in the anion is 0.1 or more and 0.5 or less And [C] a resist pattern forming method characterized by containing a polymer containing a fluorine atom and having a fluorine atom content higher than that of the polymer [A].
[A] The resist pattern forming method according to claim 1, wherein the acid dissociable group of the polymer has a monocyclic or polycyclic alicyclic hydrocarbon group.
[B] The resist pattern forming method according to claim 1, wherein the anion of the radiation-sensitive acid generator is represented by the following formula (1).

(In Formula (1), R 1 is a monovalent organic group containing a monocyclic or polycyclic alicyclic group. N is 1 or 2. R f1 and R f2 are each independently. A hydrogen atom, a fluorine atom, or a fluorinated alkyl group having 1 to 4 carbon atoms, except when both R f1 and R f2 are hydrogen atoms, and each of R f1 and R f2 has a plurality of In this case, the plurality of R f1 and R f2 may be the same or different.)
[B] The anion having an alicyclic group of the radiation-sensitive acid generator is at least one anion selected from the group consisting of anions represented by the following formulas (2) to (5): The resist pattern formation method as described in 2.
2. The resist according to claim 1, wherein the organic solvent is at least one solvent selected from the group consisting of alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and hydrocarbon solvents. Pattern forming method.
A radiation-sensitive resin composition for organic solvent development,
[A] a base polymer having an acid dissociable group,
[B] Generation of a radiation-sensitive acid containing a cation and an anion having an alicyclic group, wherein the ratio of the number of atoms (F / C) of fluorine and carbon in the anion is 0.1 or more and 0.5 or less And [C] a radiation-sensitive resin composition containing a fluorine atom and a polymer having a higher fluorine atom content than the polymer [A].