JP2009180819A - Resist composition for liquid immersion lithography, resist pattern forming method and fluorine contained copolymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resist composition for liquid immersion lithography, a resist pattern forming method and a fluorine contained copolymer. <P>SOLUTION: The resist composition for liquid immersion lithography contains base material component (A), changing in solubility to an alkali developing liquid by action of acid, an acid generating agent component (B) generating acid by exposure, and fluorine contained copolymer (C) having a component unit (c1) having a benzene ring which may have a substitution group in a side chain and a component unit (c2) having a naphthalene ring which may have a substitution group in a side chain. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resist composition for liquid immersion lithography, a method for forming a resist pattern using the resist composition for liquid immersion exposure, and a fluorine-containing copolymer.

In lithography technology, for example, a resist film made of a resist material is formed on a substrate, and the resist film is selectively exposed to radiation such as light or an electron beam through a mask on which a predetermined pattern is formed. And a development process is performed to form a resist pattern having a predetermined shape on the resist film.
Along with the miniaturization of semiconductor elements, the wavelength of an exposure light source has been shortened and the projection lens has a high numerical aperture (high NA). Currently, an exposure of NA = 0.84 using an ArF excimer laser having a wavelength of 193 nm as a light source. A machine has been developed. Along with the shortening of the wavelength of the exposure light source, the resist material is required to be improved in lithography characteristics such as sensitivity to the exposure light source and resolution capable of reproducing a pattern with a fine dimension. As a resist material that satisfies such requirements, a chemically amplified resist containing a base resin whose solubility in an alkaline developer is changed by the action of an acid and an acid generator that generates an acid upon exposure is used.
Currently, as a base resin of a chemically amplified resist used in ArF excimer laser lithography and the like, a resin having a structural unit derived from (meth) acrylic acid ester in the main chain because of its excellent transparency near 193 nm ( Acrylic resin) is generally used.
Here, “(meth) acrylic acid” means one or both of acrylic acid having a hydrogen atom bonded to the α-position and methacrylic acid having a methyl group bonded to the α-position. “(Meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position. “(Meth) acrylate” means one or both of an acrylate having a hydrogen atom bonded to the α-position and a methacrylate having a methyl group bonded to the α-position.

As one of the techniques for further improving the resolution, exposure (immersion exposure) is performed by interposing a liquid (immersion medium) having a higher refractive index than air between the objective lens of the exposure machine and the sample. A so-called immersion lithography (hereinafter referred to as “immersion exposure”) is known (for example, see Non-Patent Document 1).
According to immersion exposure, even when a light source having the same exposure wavelength is used, the same high resolution as when using a light source with a shorter wavelength or using a high NA lens can be achieved, and the depth of focus can be reduced. It is said that there is no decline. Moreover, immersion exposure can be performed using an existing exposure apparatus. For this reason, immersion exposure is expected to be able to form resist patterns with low cost, high resolution, and excellent depth of focus. In particular, in terms of lithography characteristics such as resolution, the semiconductor industry is attracting a great deal of attention.
Immersion exposure is effective in the formation of all pattern shapes, and can be combined with super-resolution techniques such as the phase shift method and the modified illumination method that are currently being studied. Currently, as an immersion exposure technique, a technique mainly using an ArF excimer laser as a light source is being actively researched. Currently, water is mainly studied as an immersion medium.

In recent years, with respect to fluorine-containing compounds, attention has been paid to characteristics such as water repellency and transparency, and research and development in various fields has been actively conducted. For example, in the field of resist materials, acid instabilities such as methoxymethyl group, tert-butyl group, and tert-butyloxycarbonyl group are added to fluorine-containing polymer compounds for use as the base resin of positive chemically amplified resists. Introducing groups. However, when such a fluorine-based polymer compound is used as a base resin of a positive resist composition, there are disadvantages such as generation of a large amount of outgas after exposure and insufficient resistance to dry etching gas (etching resistance). is there.
Recently, a fluorine-containing polymer compound having an acid labile group containing a cyclic hydrocarbon group has been reported as a fluorine-containing polymer compound having excellent etching resistance (see, for example, Non-Patent Document 2).
Proceedings of SPIE, 5754, 119-128 (2005). Proceedings of SPIE, 4690, 76-83 (2002).

  In immersion exposure, in addition to normal lithography characteristics (sensitivity, resolution, etching resistance, etc.), a resist material having characteristics corresponding to the immersion exposure technique is required. For example, in immersion exposure, when the resist film and the immersion solvent come into contact with each other, elution of the substance in the resist film into the immersion solvent (substance elution) occurs. Substance elution causes phenomena such as alteration of the resist layer and change in the refractive index of the immersion solvent, thereby deteriorating the lithography properties. Since the amount of this substance elution is affected by the characteristics (for example, hydrophilicity / hydrophobicity) of the resist film surface, for example, the elution of the substance can be reduced by increasing the hydrophobicity of the resist film surface. In the case where the immersion medium is water, when immersion exposure is performed using a scanning immersion exposure machine as described in Non-Patent Document 1, the immersion medium follows the movement of the lens. Therefore, the water following ability to move is required. If the water followability is low, the exposure speed is lowered, and there is a concern that the productivity may be affected. This water followability is considered to be improved by increasing the hydrophobicity of the resist film.

Thus, it is considered that by increasing the hydrophobicity of the resist film surface, it is possible to solve problems peculiar to the immersion exposure technology, such as reduction of substance elution and improvement of water followability. However, even if the resist film is simply hydrophobized, there is an adverse effect on lithography characteristics and the like. For example, when the hydrophobicity of the resist film increases, there is a problem that a defect is likely to occur in the resist film after alkali development. In particular, in the case of a positive resist composition, defects are likely to occur in unexposed areas. Defects are general defects detected when a developed resist film is observed from directly above with, for example, a surface defect observation apparatus (trade name “KLA”) manufactured by KLA Tencor. Examples of the defects include scum, bubbles, dust, bridges (bridge structures between resist patterns), color unevenness, precipitates, and residues after development.
It is presumed that these problems can be solved if the material has characteristics that are hydrophobic during immersion exposure and hydrophilic during development. However, at present, materials with such characteristics are hardly known.
The present invention has been made in view of the above circumstances, and is a novel fluorine-containing copolymer useful as an additive for a resist composition for immersion exposure, and immersion exposure containing the fluorine-containing copolymer. An object of the present invention is to provide a resist composition for resist and a resist pattern forming method using the resist composition for immersion exposure.

In order to achieve the above object, the present invention employs the following configuration.
That is, the first aspect of the present invention includes a base material component (A) whose solubility in an alkaline developer is changed by the action of an acid, an acid generator component (B) that generates an acid upon exposure, and the following general formula: It contains a fluorine-containing copolymer (C) having a structural unit (c1) represented by (c1-1) and a structural unit (c2) represented by the following general formula (c2-1). A resist composition for immersion exposure.

［式中、Ｒ^１はそれぞれ独立して水素原子、低級アルキル基またはハロゲン化低級アルキル基であり；Ｑ^１はそれぞれ独立して単結合または２価の連結基であり；Ａ_Ｂは置換基を有していてもよいベンゼン環であり；Ａ_Ｎは置換基を有していてもよいナフタレン環であり；Ｑ^２はそれぞれ独立して１価の親水基から水素原子１つを除いた基であり；Ｒ^２はそれぞれ独立して塩基解離性基であり；ａはそれぞれ独立して１または２であり；式（ｃ１−１）中、Ａ_Ｎおよびａ個のＲ^２のうち少なくとも１つはフッ素原子を有し；式（ｃ２−１）中、Ａ_Ｂおよびａ個のＲ^２のうち少なくとも１つはフッ素原子を有する。］

[Wherein, R ¹ is each independently a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; Q ¹ is each independently a single bond or a divalent linking group; A _B is a substituent; A is an optionally substituted benzene ring; A _N is an optionally substituted naphthalene ring; Q ² is each independently a group obtained by removing one hydrogen atom from a monovalent hydrophilic group; Yes; each R ² is independently a base dissociable group; each a is independently 1 or 2; in Formula (c1-1), at least one of A _N and a R ² is It has a fluorine atom; wherein (c2-1), at least one of _{a B} and a number of ^{R 2} is a fluorine atom. ]

  The second aspect of the present invention includes a step of forming a resist film on a support using the positive resist composition for immersion exposure according to the first aspect, a step of immersion exposure of the resist film, and the resist This is a resist pattern forming method including a step of forming a resist pattern by alkali development of a film.

  The third aspect of the present invention is a fluorine-containing copolymer having a structural unit (c1) represented by the following general formula (c1-1) and a structural unit (c2) represented by the following general formula (c2-1). It is a coalescence.

［式中、Ｒ^１はそれぞれ独立して水素原子、低級アルキル基またはハロゲン化低級アルキル基であり；Ｑ^１はそれぞれ独立して単結合または２価の連結基であり；Ａ_Ｂは置換基を有していてもよいベンゼン環であり；Ａ_Ｎは置換基を有していてもよいナフタレン環であり；Ｑ^２はそれぞれ独立して１価の親水基から水素原子１つを除いた基であり；Ｒ^２はそれぞれ独立して塩基解離性基であり；ａはそれぞれ独立して１または２であり；式（ｃ１−１）中、Ａ_Ｎおよびａ個のＲ^２のうち少なくとも１つはフッ素原子を有し；式（ｃ２−１）中、Ａ_Ｂおよびａ個のＲ^２のうち少なくとも１つはフッ素原子を有する。］

[Wherein, R ¹ is each independently a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; Q ¹ is each independently a single bond or a divalent linking group; A _B is a substituent; A is an optionally substituted benzene ring; A _N is an optionally substituted naphthalene ring; Q ² is each independently a group obtained by removing one hydrogen atom from a monovalent hydrophilic group; Yes; each R ² is independently a base dissociable group; each a is independently 1 or 2; in Formula (c1-1), at least one of A _N and a R ² is It has a fluorine atom; wherein (c2-1), at least one of _{a B} and a number of ^{R 2} is a fluorine atom. ]

In the present specification and claims, the “structural unit” means a monomer unit (monomer unit) constituting a resin component (polymer, copolymer).
“Exposure” is a concept that includes radiation exposure in general.
Unless otherwise specified, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups.
“Lower alkyl group” means an alkyl group having 1 to 5 carbon atoms.

  According to the present invention, a novel fluorine-containing copolymer useful as an additive for a resist composition for immersion exposure, a resist composition for immersion exposure containing the fluorine-containing copolymer, and the immersion exposure It is possible to provide a resist pattern forming method using the resist composition.

≪Fluorine-containing copolymer≫
First, a fluorine-containing copolymer (hereinafter referred to as a fluorine-containing copolymer (C)) which is a third aspect of the present invention will be described. The fluorine-containing copolymer (C) is a copolymer that is a constituent component of the resist composition for immersion exposure according to the first aspect of the present invention, and is suitably used as an additive for the resist composition for immersion exposure. It is used.

・ Structural unit (c1)
The fluorine-containing copolymer (C) has a structural unit (c1) represented by the general formula (c1-1).
In the formula (c1-1), a is 1 or 2, and preferably 1.
In formula (c1-1), R ¹ represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group.
Specific examples of the lower alkyl group for R ¹ include lower groups such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, and neopentyl. Examples thereof include a linear or branched alkyl group.
Specific examples of the halogenated lower alkyl group for R ¹ include groups in which some or all of the hydrogen atoms of the lower alkyl group have been substituted with halogen atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable.
R ¹ is more preferably a hydrogen atom, a lower alkyl group or a fluorinated lower alkyl group, and further preferably a hydrogen atom or a methyl group.

In formula (c1-1), Q ¹ is a single bond or a divalent linking group.
Examples of the divalent linking group for Q ¹ include a hydrocarbon group and a group containing a hetero atom.
Examples of the hydrocarbon group include an alkylene group. The alkylene group may be linear or branched. 1-12 are preferable, as for carbon number of this alkylene group, 1-5 are more preferable, and 1-3 are especially preferable. Specific examples of the alkylene group include a methylene group [—CH ₂ —]; —CH (CH ₃ ) —, —CH (CH ₂ CH ₃ ) —, —C (CH ₃ ) ₂ —, —C ( _{CH 3) (CH 2 CH 3} ) -, - C (CH 3) (CH 2 CH 2 CH 3) -, - C (CH 2 CH 3) 2 - ; alkylethylene groups such as ethylene group _[-CH 2 CH _2— ]; —CH (CH ₃ ) CH ₂ —, —CH (CH ₃ ) CH (CH ₃ ) —, —C (CH ₃ ) ₂ CH ₂ —, —CH (CH ₂ CH ₃ ) CH ₂ —, Alkylethylene groups such as —CH (CH ₂ CH ₃ ) CH ₂ —; trimethylene group (n-propylene group) [—CH ₂ CH ₂ CH ₂ —]; —CH (CH ₃ ) CH ₂ CH ₂ —, —CH _{2 CH (CH 3) CH 2} - alkyl trimethylene group and the like; Toramechiren group _{[-CH 2 CH 2 CH 2 CH} 2 -]; - CH (CH 3) CH 2 CH 2 CH 2 -, - CH 2 CH (CH 3) CH 2 CH 2 - alkyl tetramethylene group and the like; penta And methylene group [—CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ —] and the like.
A hetero atom is an atom other than a carbon atom and a hydrogen atom, and examples thereof include an oxygen atom, a nitrogen atom, a sulfur atom, and a halogen atom. As the group containing a hetero atom, for example, —O—, —C (═O) —, —C (═O) —O—, —NH—, —NR ⁰⁴ (R ⁰⁴ is an alkyl group) —, —NH -C (= O)-, = N-, combinations of these groups with divalent hydrocarbon groups, and the like.
Q ¹ is preferably a single bond or —C (═O) —O—, and more preferably a single bond.

Wherein (c1-1), _{A B} is a benzene ring which may have a substituent. That is, it is a group obtained by removing two hydrogen atoms from a benzene ring which may have a substituent.
In A _B , examples of the substituent that the benzene ring may have include a halogen atom, an alkyl group, an alkoxy group, a halogenated lower alkyl group, and an oxygen atom (═O). Examples of the halogen atom include a fluorine atom, a chlorine atom, an iodine atom, and a bromine atom. Examples of the halogenated lower alkyl group include —CF ₃ , —C ₂ F ₅ , —C ₃ F _{7 and the} like. The benzene ring substituent which may have the A _B, is preferably a fluorine atom or -CF _3.
The benzene ring A _B, may be one having no substituent, but may have a substituent group, it is preferable that no substituent. When the benzene ring A _B has a substituent, the number of substituents may be one, may be two or more, preferably one or two, more preferably One.

In formula (c1-1), in Q ² , the monovalent hydrophilic group may be any group having at least one hydrogen atom, such as a hydroxyl group (—OH), a carboxy group (—C (═O) OH, ), An amino group (—NH ₂ ) and the like.
Q ² is a group obtained by removing one hydrogen atom from a monovalent hydrophilic group as described above. For example, when the monovalent hydrophilic group is —OH, Q ² is —O—. When the monovalent hydrophilic group is —C (═O) OH, Q ² is —C (═O) O—. When the monovalent hydrophilic group is —NH ₂ , Q ² is —NH—.
Q ² is preferably —O— or —C (═O) O—, more preferably —O—.

In formula (c1-1), R ² is a base dissociable group.
In the present specification and claims, the “base dissociable group” is an organic group that can be dissociated by the action of a base. That is, the “base dissociable group” is dissociated by the action of an alkali developer (for example, a 2.38 mass% TMAH aqueous solution at 23 ° C.). Since the fluorine-containing copolymer (C) has a base dissociable group, the base dissociable group is dissociated by the action of an alkali developer, and a monovalent hydrophilic group (here, -A _B -Q ² H ) And the affinity for an alkaline developer is increased.
The base dissociable group is not particularly limited as long as it falls within the above definition. However, the fluorine-containing copolymer (C), in its structure, of the structural unit (c1), at least one of A _B and a number of R ² is a fluorine atom. Therefore, in the structural unit (c1), if the A _B has no fluorine atom, a base dissociable group having at least one R ² is a fluorine atom. If A _B has a fluorine atom, R ² may have a fluorine atom, or may not have.
Specific examples of the base dissociable group are preferably at least one selected from the groups represented by the following general formulas (II-1) to (II-3), and are excellent in the effects of the present invention. In view of easy synthesis, a group represented by the following general formula (II-1) is particularly preferred.

［式中、Ｒ^４はそれぞれ独立してフッ素原子を有していてもよい炭化水素基である。］

[Wherein, each R ⁴ is independently a hydrocarbon group optionally having a fluorine atom. ]

In formulas (II-1) to (II-3), R ⁴ is a hydrocarbon group which may have a fluorine atom.
The hydrocarbon group of R ⁴ may be an unsubstituted hydrocarbon group consisting only of carbon atoms and hydrogen atoms, and part or all of the hydrogen atoms of the unsubstituted hydrocarbon group are substituted with fluorine atoms. It may be a fluorine-substituted hydrocarbon group.
The hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group.
Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean groups, compounds, and the like that do not have aromaticity.
The aliphatic hydrocarbon group is a hydrocarbon group having no aromaticity. The aliphatic hydrocarbon group may be saturated or unsaturated, but is usually preferably saturated. That is, the aliphatic hydrocarbon group is preferably an unsubstituted alkyl group or a fluorine-substituted alkyl group.

The unsubstituted alkyl group may be linear, branched or cyclic, and may be a combination of a linear or branched alkyl group and a cyclic alkyl group.
As an unsubstituted linear alkyl group, C1-C10 is preferable and C1-C8 is more preferable. Specifically, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n- A decanyl group etc. are mentioned.
As an unsubstituted branched alkyl group, C3-C10 is preferable and C3-C8 is more preferable. As the branched alkyl group, a tertiary alkyl group is preferable, and a group represented by the following general formula (III-1) is particularly preferable.

［式中、Ｒ^７〜Ｒ^９は、それぞれ独立に、炭素数１〜５の直鎖状のアルキル基である。］

[In formula, R < ⁷ > -R < ⁹ > is a C1-C5 linear alkyl group each independently. ]

As the alkyl group for R ^{7 to} R ⁹ , an ethyl group or a methyl group is preferable, and a methyl group is particularly preferable.

Examples of the unsubstituted cyclic alkyl group include a group in which one hydrogen atom has been removed from a monocycloalkane or a polycycloalkane such as bicycloalkane, tricycloalkane, and tetracycloalkane. Specific examples include monocycloalkyl groups such as cyclopentyl group and cyclohexyl group; polycycloalkyl groups such as adamantyl group, norbornyl group, isobornyl group, tricyclodecanyl group, and tetracyclododecanyl group.
The combination of an unsubstituted linear or branched alkyl group and a cyclic alkyl group includes a group in which a cyclic alkyl group is bonded as a substituent to a linear or branched alkyl group, or a cyclic alkyl group And a group in which a linear or branched alkyl group is bonded as a substituent.

Examples of the fluorine-substituted alkyl group include groups in which some or all of the hydrogen atoms of the above-described unsubstituted alkyl group are substituted with fluorine atoms.
The fluorine-substituted alkyl group may be a group in which part of the hydrogen atoms of the unsubstituted alkyl group is substituted with fluorine atoms, or a group in which all of the hydrogen atoms of the unsubstituted alkyl group are substituted with fluorine atoms ( Perfluoroalkyl group).
In R ⁴ , the fluorine-substituted alkyl group is preferably a linear or branched fluorine-substituted alkyl group, particularly —R ⁴¹ —R ⁴² [wherein R ⁴¹ is an unsubstituted C 1-9 carbon atom. An alkylene group, and R ⁴² is a fluorine-substituted alkyl group having 1 to 9 carbon atoms. However, the total number of carbon atoms of R ⁴¹ and R ⁴² is 10 or less. ] Is preferable.
In the formula, R ⁴¹ is preferably a linear or branched alkylene group having 1 to 5 carbon atoms, particularly preferably a methylene group, an ethylene group or a propylene group.
R ⁴² is preferably a linear or branched fluorine-substituted alkyl group having 1 to 5 carbon atoms, particularly preferably a perfluoroalkyl group. Of these, a trifluoromethyl group and a tetrafluoroethyl group are preferable.

  The structural unit (c1) is preferably a structural unit represented by the following general formula (c1-1-1), a structural unit represented by (c1-1-2), or the like.

［式中、Ｒ^１、Ｒ^２、Ａ_Ｂおよびａはそれぞれ式（ｃ１−１）と同じである。］

_{^{Wherein, R 1, R 2, A}} B and a are the same as defined formula (c1-1). ]

The structural unit represented by the general formula (c1-1-1) is preferably a structural unit represented by the following general formula (c1-1-11) or (c1-1-12).
The structural unit represented by the general formula (c1-1-2) is preferably a structural unit represented by the following general formula (c1-1-21) or (c1-1-22).

［式中、Ｒ^５１は水素原子、低級アルキル基またはハロゲン化低級アルキル基であり；Ｒ^５２〜Ｒ^５５はそれぞれ独立に水素原子またはフッ素原子であり；Ｒ^２１は少なくとも１のフッ素原子を有する塩基解離性基である。Ｒ^５１’は水素原子、低級アルキル基またはハロゲン化低級アルキル基であり；Ｒ^５２’〜Ｒ^５５’はそれぞれ独立に水素原子またはフッ素原子であって、Ｒ^５２’〜Ｒ^５５’のうちの少なくとも１つはフッ素原子であり；Ｒ^２は塩基解離性基である。］

[Wherein R ⁵¹ represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; R ^{52 to} R ⁵⁵ each independently represents a hydrogen atom or a fluorine atom; R ²¹ represents a base having at least one fluorine atom. It is a dissociable group. R ⁵¹ ′ is a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; R ⁵² ′ to R ⁵⁵ ′ are each independently a hydrogen atom or a fluorine atom, and at least one of R ⁵² ′ to R ⁵⁵ ′ One is a fluorine atom; R ² is a base dissociable group. ]

Examples of R ⁵¹ include the same as R ¹ described above. R ⁵¹ is preferably a hydrogen atom, a lower alkyl group or a fluorinated lower alkyl group, more preferably a hydrogen atom or a methyl group.
R ²¹ is a base dissociable group having at least one fluorine atom. Examples of R ²¹ include the same groups as those having a fluorine atom among the base dissociable groups exemplified in R ² .
R ^{52 to} R ⁵⁵ are each independently a hydrogen atom or a fluorine atom. In formulas (c1-1-11) and (c1-1-21), in consideration of ease of production and the like, all of R ^{52 to} R ⁵⁵ are hydrogen atoms, or all of R ^{52 to} R ⁵⁵ Is preferably a fluorine atom.

Examples of R ⁵¹ ′ include the same as R ¹ described above. R ⁵¹ ′ is preferably a hydrogen atom, a lower alkyl group or a fluorinated lower alkyl group, more preferably a hydrogen atom or a methyl group.
R ² is the same as described above.
R ⁵² ′ to R ⁵⁵ ′ are each independently a hydrogen atom or a fluorine atom, and at least one of R ⁵² ′ to R ⁵⁵ ′ is a fluorine atom. In formulas (c1-1-12) and (c1-1-22), it is preferable that all of R ⁵² ′ to R ⁵⁵ ′ are fluorine atoms in view of ease of production and the like.

  As the fluorine-containing copolymer (C), the structural unit (c1) is represented by the following general formulas (c1-1-111), (c1-1-112), (c1-1-121), (c1-1- 122), (c1-1-211), (c1-1-212), (c1-1-221), and (c1-1-222) are preferable, and the following general formula (c1-1-111) (C1-1-112) is more preferable.

［式中、Ｒ^５１、Ｒ^５１’、Ｒ^７、Ｒ^８、Ｒ^９、Ｒ^４１およびＲ^４２はそれぞれ前記と同じである。Ｒ^７１、Ｒ^８１およびＲ^９１はそれぞれ独立に、炭素数１〜５の直鎖状のアルキル基であり、Ｒ^７１、Ｒ^８１およびＲ^９１の少なくとも１つはフッ素原子を有するアルキル基である。］

[Wherein, R ⁵¹ , R ⁵¹ ′, R ⁷ , R ⁸ , R ⁹ , R ⁴¹ and R ⁴² are the same as defined above. R ⁷¹ , R ⁸¹ and R ⁹¹ are each independently a linear alkyl group having 1 to 5 carbon atoms, and at least one of R ⁷¹ , R ⁸¹ and R ⁹¹ is an alkyl group having a fluorine atom. ]

As the alkyl group for R ⁷¹ , R ⁸¹ and R ⁹¹ , an ethyl group or a methyl group is preferable, and a methyl group is particularly preferable. Any one of the alkyl groups of R ⁷¹ , R ⁸¹ and R ⁹¹ may be a fluorine-substituted alkyl group, and all may be combined with a fluorine-substituted alkyl group.

In the fluorinated copolymer (C), as the structural unit (c1), one type may be used alone, or two or more types may be used in combination.
In the fluorine-containing copolymer (C), the proportion of the structural unit (c1) is preferably 1 mol% or more and less than 100 mol% with respect to the total of all the structural units constituting the fluorine-containing copolymer (C). -60 mol% is more preferable, 1-50 mol% is further more preferable, 1-40 mol% is especially preferable, and 10-30 mol% is the most preferable.

・ Structural unit (c2)
The fluorine-containing copolymer (C) has a structural unit (c2) represented by the general formula (c2-1) in addition to the structural unit (c1).
In formula (c2-1), R ¹ represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group. The lower alkyl group and a halogenated a lower alkyl group of R ^1, it is possible to include the same as R ¹ of formula (c1-1).
In formula (c2-1), Q ¹ is a single bond or a divalent linking group. Examples of the divalent linking group for Q ¹ include the same groups as those for Q ^{1 in} formula (c1-1). As the structural unit (c2), Q ¹ is preferably a single bond or an alkylene group, and more preferably a single bond.

Wherein (c2-1), _{A N} is the naphthalene ring that may have a substituent. That is, a group obtained by removing two hydrogen atoms from a naphthalene ring which may have a substituent.
In A _N, as the substituent that may be possessed by a naphthalene ring, it may be the same as those benzene ring A _B are given as the substituent which may have. The substituent which the naphthalene ring of A _N may have is preferably a fluorine atom.
The naphthalene ring of A _N, may be one having no substituent, but may have a substituent group, it is preferable that no substituent. When the naphthalene ring of A _N has a substituent, the number of substituents may be one or two or more, preferably one or two, more preferably One.
In formula (c2-1), Q ² is a monovalent hydrophilic group. As the monovalent hydrophilic group of Q ^2, the same monovalent hydrophilic group as Q ^{2 in} formula (c1-1) can be exemplified.

In Formula (c2-1), R ² is a base dissociable group. The R ^2, may be mentioned the same as ^{R 2} of formula (c1-1). However, in the structure of the fluorine-containing copolymer (C), at least one of A _N and a R ² in the structural unit (c2) has a fluorine atom. Therefore, in the structural unit (c2), if A _N is no fluorine atom, a base dissociable group having at least one R ² is a fluorine atom. When A _N has a fluorine atom, R ² may or may not have a fluorine atom.

  The structural unit (c2) is preferably a structural unit represented by the following general formula (c2-1-1), a structural unit represented by (c2-1-2), or the like.

［式中、Ｒ^１、Ｒ^２、Ａ_Ｎおよびａはそれぞれ式（ｃ２−１）と同じである。］

[Wherein, R ¹ , R ² , A _N and a are the same as in formula (c2-1). ]

The structural unit represented by the general formula (c2-1-1) is preferably a structural unit represented by the following general formula (c2-1-11) or (c2-1-12).
The structural unit represented by the general formula (c2-1-2) is preferably a structural unit represented by the following general formula (c2-1-21) or (c2-1-22).

［式中、Ｒ^６１は水素原子、低級アルキル基またはハロゲン化低級アルキル基であり；Ｒ^６２およびＲ^６３はそれぞれ独立に置換基であり；Ｒ^２１は少なくとも１のフッ素原子を有する塩基解離性基であり；ｂは１または２であり；ｃは０〜３の整数であり；ｄは０〜３の整数であり；ｂ＋ｄは１〜４の整数である。Ｒ^６１’は水素原子、低級アルキル基またはハロゲン化低級アルキル基であり；Ｒ^６２’およびＲ^６３’はそれぞれ独立に置換基であって、ｃ’個のＲ^６２’とｄ’個のＲ^６３’のうち、少なくとも１つはフッ素原子を有する置換基であり；Ｒ^２は塩基解離性基であり；ｂ’は１または２であり；ｃ’は０〜３の整数であり；ｄ’は０〜３の整数であり；ｂ’＋ｄ’は１〜４の整数である。

[Wherein, R ⁶¹ represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; R ⁶² and R ⁶³ each independently represent a substituent; R ²¹ represents a base-dissociable group having at least one fluorine atom. B is 1 or 2, c is an integer of 0-3; d is an integer of 0-3; b + d is an integer of 1-4. R ⁶¹ ′ is a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; R ⁶² ′ and R ⁶³ ′ are each independently a substituent, and are c ′ R ⁶² ′ and d ′ R ^63. At least one is a substituent having a fluorine atom; R ² is a base-dissociable group; b ′ is 1 or 2; c ′ is an integer from 0 to 3; An integer from 0 to 3; b ′ + d ′ is an integer from 1 to 4.

^Examples of R ⁶¹ include those similar to R ⁵¹ described above. R ⁶¹ is preferably a hydrogen atom, a lower alkyl group or a fluorinated lower alkyl group, more preferably a hydrogen atom or a methyl group.
R ²¹ is a base dissociable group having at least one fluorine atom. Examples of R ²¹ include the same groups as those having a fluorine atom among the base dissociable groups exemplified in R ² .
The substituent of R ⁶² and R ^63, wherein in A _N, although naphthalene ring include the same as those cited as the substituent which may have, is preferably a fluorine atom. In formulas (c2-1-11) and (c2-1-21), considering ease of production, c is 0 and d is 0, or c is 3, and d is 4-b, and R ⁶² and R ⁶³ are more preferably a fluorine atom.

Examples of R ⁶¹ ′ include the same as R ⁵¹ described above. R ⁶¹ ′ is preferably a hydrogen atom, a lower alkyl group or a fluorinated lower alkyl group, more preferably a hydrogen atom or a methyl group.
R ² is the same as described above.
R ⁶² ′ and R ⁶³ ′ are each independently a substituent, and at least one of c ′ R ⁶² ′ and d ′ R ⁶³ ′ is a substituent having a fluorine atom. The substituent of R ^{62 'and} R ^63', wherein in A _N, include the same ones as mentioned as the substituent which may be possessed by the naphthalene ring is preferably a fluorine atom. In formulas (c2-1-12) and (c2-1-22), in consideration of ease of production, c ′ R ⁶² ′ and d ′ R ⁶³ ′ are all fluorine atoms. Is preferred.

  As the fluorine-containing copolymer (C), the structural unit (c2) is represented by the following general formulas (c2-1-111) to (c2-1-114), (c2-1-121), (c2-1-1- 122), (c2-11-211) to (c2-1-214), (c2-1-221), and (c2-1-222), preferably represented by the following general formula (c2-1-111) (C2-1-112) is more preferable.

［式中、Ｒ^６１、Ｒ^６１’、Ｒ^４１、Ｒ^４２、Ｒ^７、Ｒ^８、Ｒ^９、Ｒ^７１、Ｒ^８１およびＲ^９１はそれぞれ前記と同じである。］

[Wherein, R ⁶¹ , R ⁶¹ ′, R ⁴¹ , R ⁴² , R ⁷ , R ⁸ , R ⁹ , R ⁷¹ , R ⁸¹ and R ⁹¹ are the same as defined above. ]

As the alkyl group for R ⁷¹ , R ⁸¹ and R ⁹¹ , an ethyl group or a methyl group is preferable, and a methyl group is particularly preferable. Any one of the alkyl groups of R ⁷¹ , R ⁸¹ and R ⁹¹ may be a fluorine-substituted alkyl group, and all may be combined with a fluorine-substituted alkyl group.

In the fluorine-containing copolymer (C), as the structural unit (c2), one type may be used alone, or two or more types may be used in combination.
In the fluorinated copolymer (C), the proportion of the structural unit (c2) is preferably 40 mol% or more and less than 100 mol%, based on the total of all the structural units constituting the fluorinated copolymer (C). More preferably, it is more than mol% and less than 100 mol%, more preferably more than 60 mol% and less than 100 mol%, particularly preferably 60 to 99 mol%.

・ Structural unit (c3)
The fluorine-containing copolymer (C) may have a structural unit (c3) other than the structural units (c1) and (c2) as long as the effects of the present invention are not impaired. Such a structural unit is not particularly limited, but is preferably a structural unit represented by the following general formula (c0-1). In addition, for example, in the resist composition for immersion exposure described later, the structural units (a1) to (a4) listed as the resin component (A1) may have, structural units derived from hydroxystyrene, Examples include structural units derived from styrene.

［式（ｃ０−１）中、Ｒ^１、Ｑ^１、Ｑ^２およびａはそれぞれ前記と同じであり、Ａは置換基を有していても良いナフタレン環またはベンゼン環である。］

[In formula (c0-1), R ¹ , Q ¹ , Q ² and a are the same as defined above, and A represents a naphthalene ring or a benzene ring which may have a substituent. ]

The mass average molecular weight (Mw) (polystyrene conversion standard by gel permeation chromatography) of the fluorinated copolymer (C) is not particularly limited, but preferably 2000 to 50000, more preferably 3000 to 30000, 5000 to 20000 is most preferred. When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist. When it is larger than the lower limit of this range, dry etching resistance and resist pattern cross-sectional shape are good.
Further, the dispersity (Mw / Mn) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5. In addition, Mn shows a number average molecular weight.

<Method for producing fluorine-containing copolymer (C)>
The fluorine-containing copolymer (C) is a monomer derived from each structural unit, for example, azobisisobutyronitrile (AIBN), dimethyl-2,2′-azobis (2-methylpropionate (V-601). It can be obtained by polymerization by a known radical polymerization using a radical polymerization initiator such as)).
Here, examples of the monomer for deriving the structural unit (c1) or (c2) include a monomer represented by the following general formula (c0-1) (hereinafter referred to as a fluorine-containing compound (C0)).

［式（ｃ０−１）中、Ｒ^１、Ｑ^１、Ａ、Ｑ^２、Ｒ^２およびａはそれぞれ前記と同じである。］

[In Formula (c0-1), R ¹ , Q ¹ , A, Q ² , R ² and a are the same as defined above. ]

The fluorine-containing compound (C0) is, for example, a base-dissociable group on the hydrophilic group -Q ² H of a monomer represented by the following general formula (c0-1-0) (hereinafter referred to as monomer (V-1)). ^-R 2 ^{[R 2} is is as defined above. ] Can be produced. Introduction of the group represented by —R ² can be carried out using a conventionally known method. For example, the fluorine-containing compound (C0) can be produced by reacting the monomer (V-1) with the compound (V-2) represented by the following general formula (V-2).

［式中、Ｒ^１、Ｑ^１、Ａ、Ｑ^２、Ｒ^２およびａはそれぞれ前記と同じである。また、Ｘ^ｈはハロゲン原子または水酸基である。］

[Wherein, R ¹ , Q ¹ , A, Q ² , R ² and a are the same as defined above. X ^h is a halogen atom or a hydroxyl group. ]

Examples of the halogen atom for X ^h, a bromine atom, a chlorine atom, an iodine atom and a fluorine atom. X ^h is preferably a bromine atom or a chlorine atom because of excellent reactivity, and a chlorine atom is particularly preferred.
The method for reacting the monomer (V-1) and the compound (V-2) is not particularly limited. For example, the monomer (V-1) and the compound (V-2) are reacted in the reaction solvent in the presence of a base. ). The method if X ^h is a halogen atom, for example, the presence of a base, to a solution monomer (V-1) is dissolved in a reaction solvent can be carried out by adding the compound (V-2). When ^Xh is a hydroxyl group, for example, the monomer (V-1) is added to a solution in which the compound (V-2) is dissolved in the reaction solvent in the presence of a base and a condensing agent. V-1) and compound (V-2) can be reacted (condensation reaction). When ^Xh is a hydroxyl group, for example, the monomer (V-1) is added by adding the monomer (V-1) to a solution in which the compound (V-2) is dissolved in the reaction solvent in the presence of an acid. ) And the compound (V-2) can be reacted (condensation reaction).
As a monomer (V-1) and a compound (V-2), a commercially available thing may be used and you may synthesize | combine.
Any reaction solvent may be used as long as it can dissolve the raw material monomer (V-1) and compound (V-2). Specifically, tetrahydrofuran (THF), acetone, dimethylformamide (DMF), dimethylacetamide , Dimethyl sulfoxide (DMSO), acetonitrile and the like.
Examples of the base include organic bases such as triethylamine, 4-dimethylaminopyridine (DMAP) and pyridine; inorganic bases such as sodium hydride, K ₂ CO ₃ and Cs ₂ CO ₃ .
As the acid, those usually used in dehydration condensation can be used. Specifically, inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, p-toluene. Examples include organic acids such as sulfonic acid. These may be used alone or in combination of two or more.
Examples of the condensing agent include carbodiimide reagents such as ethyldiisopropylaminocarbodiimide hydrochloride (EDCI), dicyclohexylcarboimide (DCC), diisopropylcarbodiimide, carbodiimidazole, tetraethylpyrophosphate, benzotriazole-N-hydroxytrisdimethylaminophosphonium hexa Fluorophosphide salt (Bop reagent) and the like.
About 1-3 equivalent is preferable with respect to monomer (V-1), and, as for the addition amount of a compound (V-2), 1-2 equivalent is more preferable.
The reaction temperature is preferably -20 to 40 ° C, more preferably 0 to 30 ° C.
The reaction time varies depending on the reactivity of the monomer (V-1) and compound (V-2), the reaction temperature, and the like, but is usually preferably 30 to 240 minutes, more preferably 60 to 180 minutes.

In addition, in the fluorine-containing copolymer (C), -Q ² H [Q ² is the same as described above. As described above, the above-mentioned general formulas (II-1) to (II-) are added to the hydrophilic group of the copolymer having a hydrophilic group represented by formula (hydroxystyrene resin such as polyhydroxystyrene, acrylic resin, etc.). —R ² such as the group represented by 3) [R ² is the same as defined above. ] Can also be produced.

The fluorine-containing copolymer (C) of the present invention described above is a novel one that has not been known so far.
The fluorine-containing copolymer (C) can be suitably used as an additive for the resist composition, and the resist composition to which the fluorine-containing copolymer (C) is added is useful for immersion exposure.
The resist composition to which the fluorinated copolymer (C) is added is not particularly limited as long as it is used for immersion exposure. A chemically amplified resist composition containing a material component and an acid generator component that generates an acid upon irradiation with radiation is suitable.
The fluorine-containing copolymer (C) is particularly suitable for the resist composition for immersion exposure of the present invention described below.

≪Resist composition for immersion exposure≫
Next, the resist composition for immersion exposure, which is the first aspect of the present invention, will be described.
The resist composition for immersion exposure of the present invention comprises a base component (A) whose solubility in an alkaline developer is changed by the action of an acid (hereinafter referred to as component (A)), and an acid that generates an acid upon exposure. Generator component (B) (hereinafter referred to as component (B)) and fluorine-containing copolymer (C) having a structural unit (c1) represented by the following general formula (c1-1) (hereinafter referred to as (C ) Component)).

<(A) component>
As the component (A), organic compounds that are usually used as base components for chemically amplified resists can be used alone or in combination of two or more.
Here, the “base material component” is an organic compound having a film forming ability, and an organic compound having a molecular weight of 500 or more is preferably used. When the molecular weight of the organic compound is 500 or more, the film-forming ability is improved and a nano-level resist pattern is easily formed.
The organic compound having a molecular weight of 500 or more used as the substrate component is a low molecular weight organic compound (low molecular material) having a molecular weight of 500 or more and less than 2000 and a high molecular weight organic compound (polymer material) having a molecular weight of 2000 or more. It is divided roughly. As the low molecular weight material, a non-polymer is usually used. Resin (polymer, copolymer) is used as the polymer material, and the “molecular weight” is a polystyrene-reduced mass average molecular weight measured by GPC (gel permeation chromatography). Hereinafter, the term “resin” refers to a resin having a molecular weight of 2000 or more.
As the component (A), a resin whose alkali solubility is changed by the action of an acid can be used, and a low molecular weight material whose alkali solubility is changed by the action of an acid can also be used.

When the resist composition for immersion exposure of the present invention is a negative resist composition, as the component (A), a base material component that is soluble in an alkali developer is used, and a crosslinking agent is further added to the negative resist composition. Blended.
In such a negative resist composition, when an acid is generated from the component (B) by exposure, the acid acts to cause cross-linking between the base component and the cross-linking agent, resulting in poor solubility in an alkali developer. To do. Therefore, in the formation of the resist pattern, when the resist film obtained by coating the negative resist composition on the substrate is selectively exposed, the exposed portion turns into poorly soluble in an alkaline developer, while unexposed. Since the portion remains soluble in the alkali developer and does not change, a resist pattern can be formed by alkali development.
As the component (A) of the negative resist composition, a resin that is soluble in an alkali developer (hereinafter referred to as an alkali-soluble resin) is usually used.
As the alkali-soluble resin, a resin having a unit derived from at least one selected from α- (hydroxyalkyl) acrylic acid or a lower alkyl ester of α- (hydroxyalkyl) acrylic acid is a good resist with little swelling. A pattern can be formed, which is preferable. Note that α- (hydroxyalkyl) acrylic acid includes acrylic acid in which a hydrogen atom is bonded to the α-position carbon atom to which the carboxy group is bonded, and a hydroxyalkyl group (preferably having 1 carbon atom) in the α-position carbon atom. One or both of [alpha] -hydroxyalkylacrylic acids to which (5) hydroxyalkyl groups) are attached.
As the crosslinking agent, for example, it is usually preferable to use an amino crosslinking agent such as glycoluril having a methylol group or an alkoxymethyl group because a good resist pattern with less swelling can be formed. It is preferable that the compounding quantity of a crosslinking agent is 1-50 mass parts with respect to 100 mass parts of alkali-soluble resin.

  When the resist composition for immersion exposure according to the present invention is a positive resist composition, as the component (A), a base material component whose solubility in an alkaline developer is increased by the action of an acid is used. The component (A) is hardly soluble in an alkali developer before exposure. When an acid is generated from the component (B) by exposure, the solubility in the alkali developer is increased by the action of the acid. Therefore, in the formation of the resist pattern, when the resist film obtained by applying the positive resist composition on the substrate is selectively exposed, the exposed portion changes from poorly soluble to soluble in an alkaline developer. On the other hand, since the unexposed portion remains hardly soluble in alkali and does not change, a resist pattern can be formed by alkali development.

In the resist composition of the present invention, the component (A) is preferably a base material component whose solubility in an alkaline developer is increased by the action of an acid. That is, the resist composition of the present invention is preferably a positive resist composition.
The component (A) may be a resin component (A1) (hereinafter also referred to as component (A1)) whose solubility in an alkaline developer is increased by the action of an acid. It may be a low molecular weight material (A2) (hereinafter, also referred to as component (A2)) whose solubility in a liquid is increased, or a mixture thereof.

[(A1) component]
As the component (A1), resin components (base resins) that are usually used as base components for chemically amplified resists can be used alone or in combination of two or more.
In the present invention, the component (A1) preferably contains a structural unit derived from an acrylate ester.
Here, in the present specification and claims, the “structural unit derived from an acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of an acrylate ester.
“Acrylic acid esters” include not only acrylic acid esters in which a hydrogen atom is bonded to the α-position carbon atom, but also those in which a substituent (an atom or group other than a hydrogen atom) is bonded to the α-position carbon atom. Include concepts. Examples of the substituent include a lower alkyl group and a halogenated lower alkyl group.
Note that the α position (α-position carbon atom) of a structural unit derived from an acrylate ester means a carbon atom to which a carbonyl group is bonded unless otherwise specified.
In the acrylate ester, as the lower alkyl group as a substituent at the α-position, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, Examples include lower linear or branched alkyl groups such as isopentyl group and neopentyl group.
Specific examples of the halogenated lower alkyl group include groups in which part or all of the hydrogen atoms in the above-mentioned “lower alkyl group as a substituent at the α-position” are substituted with halogen atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable.
In the present invention, the α-position of the acrylate ester is preferably a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, and is a hydrogen atom, a lower alkyl group or a fluorinated lower alkyl group. In view of industrial availability, a hydrogen atom or a methyl group is most preferable.

The component (A1) particularly preferably has a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group.
In addition to the structural unit (a1), the component (A1) preferably further has a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.
The component (A1) is a structural unit derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group in addition to the structural unit (a1) or in addition to the structural units (a1) and (a2). It is preferable to have (a3).

・ Structural unit (a1)
The acid dissociable, dissolution inhibiting group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire component (A1) difficult to dissolve in an alkali developer before dissociation, and dissociates with an acid. This increases the solubility of the entire component in an alkaline developer, and those that have been proposed as acid dissociable, dissolution inhibiting groups for base resins for chemically amplified resists can be used. In general, a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group in (meth) acrylic acid or the like; an acetal-type acid dissociable, dissolution inhibiting group such as an alkoxyalkyl group is widely known. .

Here, the “tertiary alkyl ester” is an ester formed by replacing a hydrogen atom of a carboxy group with a chain or cyclic alkyl group, and the carbonyloxy group (—C (O)). A structure in which the tertiary carbon atom of the chain or cyclic alkyl group is bonded to the terminal oxygen atom of -O-). In this tertiary alkyl ester, when an acid acts, a bond is cut between an oxygen atom and a tertiary carbon atom.
The chain or cyclic alkyl group may have a substituent.
Hereinafter, a group that is acid dissociable by constituting a carboxy group and a tertiary alkyl ester is referred to as a “tertiary alkyl ester type acid dissociable, dissolution inhibiting group” for convenience.
Examples of the tertiary alkyl ester type acid dissociable, dissolution inhibiting group include an aliphatic branched acid dissociable, dissolution inhibiting group and an acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group.

“Aliphatic branched” means having a branched structure having no aromaticity. The structure of the “aliphatic branched acid dissociable, dissolution inhibiting group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated.
As the aliphatic branched acid dissociable, dissolution inhibiting group, a tertiary alkyl group having 4 to 8 carbon atoms is preferable, and specific examples include a tert-butyl group, a tert-pentyl group, and a tert-heptyl group. .

The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
The “aliphatic cyclic group” in the structural unit (a1) may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, a lower alkoxy group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxygen atom (= O), and the like.
The basic ring structure excluding the substituent of the “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated. The “aliphatic cyclic group” is preferably a polycyclic group.
Examples of the aliphatic cyclic group include monocycloalkanes, bicycloalkanes, tricycloalkanes, tetracycloalkanes which may or may not be substituted with a lower alkyl group, a fluorine atom or a fluorinated alkyl group. And groups obtained by removing one or more hydrogen atoms from a polycycloalkane. More specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. .

  Examples of the acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group include a group having a tertiary carbon atom on the ring skeleton of a cyclic alkyl group. Specifically, 2-methyl-2 -Adamantyl group, 2-ethyl-2-adamantyl group, etc. are mentioned. Alternatively, in the structural units represented by the following general formulas (a1 ″ -1) to (a1 ″ -6), an adamantyl group such as a group bonded to an oxygen atom of a carbonyloxy group (—C (O) —O—) An aliphatic cyclic group such as a cyclohexyl group, a cyclopentyl group, a norbornyl group, a tricyclodecanyl group, or a tetracyclododecanyl group, and a branched alkylene group having a tertiary carbon atom bonded thereto. Groups.

［式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基を示し；Ｒ^１５、Ｒ^１６はアルキル基（直鎖状、分岐鎖状のいずれでもよく、好ましくは炭素数１〜５である）を示す。］

[Wherein, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; R ¹⁵ and R ¹⁶ may be alkyl groups (both linear and branched, preferably 1 to 5 carbon atoms). Is). ]

  In the general formulas (a1 ″ -1) to (a1 ″ -6), the lower alkyl group or halogenated lower alkyl group of R is a lower alkyl group or halogenated lower alkyl which may be bonded to the α-position of the acrylate ester. It is the same as the alkyl group.

The “acetal-type acid dissociable, dissolution inhibiting group” is generally bonded to an oxygen atom by substituting a hydrogen atom at the terminal of an alkali-soluble group such as a carboxy group or a hydroxyl group. When an acid is generated by exposure, this acid acts to break the bond between the acetal acid dissociable, dissolution inhibiting group and the oxygen atom to which the acetal acid dissociable, dissolution inhibiting group is bonded.
Examples of the acetal type acid dissociable, dissolution inhibiting group include a group represented by the following general formula (p1).

［式中、Ｒ^１’，Ｒ^２’はそれぞれ独立して水素原子または低級アルキル基を表し、ｎは０〜３の整数を表し、Ｙは低級アルキル基または脂肪族環式基を表す。］

[Wherein, R ¹ ′ and R ² ′ each independently represents a hydrogen atom or a lower alkyl group, n represents an integer of 0 to 3, and Y represents a lower alkyl group or an aliphatic cyclic group. ]

In the above formula, n is preferably an integer of 0 to 2, more preferably 0 or 1, and most preferably 0.
Examples of the lower alkyl group for R ¹ ′ and R ² ′ include the same lower alkyl groups as those described above for R. A methyl group or an ethyl group is preferable, and a methyl group is most preferable.
In the present invention, it is preferable that at least one of R ¹ ′ and R ² ′ is a hydrogen atom. That is, the acid dissociable, dissolution inhibiting group (p1) is preferably a group represented by the following general formula (p1-1).

［式中、Ｒ^１’、ｎ、Ｙは上記と同様である。］

Wherein, ^{R 1} ', n, Y are as defined above. ]

Examples of the lower alkyl group for Y include the same lower alkyl groups as those described above for R.
The aliphatic cyclic group for Y can be appropriately selected from monocyclic or polycyclic aliphatic cyclic groups that have been proposed in a number of conventional ArF resists. For example, the above “aliphatic ring” Examples thereof are the same as those in the formula group.

  Examples of the acetal type acid dissociable, dissolution inhibiting group also include a group represented by the following general formula (p2).

［式中、Ｒ^１７、Ｒ^１８はそれぞれ独立して直鎖状もしくは分岐鎖状のアルキル基または水素原子であり、Ｒ^１９は直鎖状、分岐鎖状または環状のアルキル基である。または、Ｒ^１７およびＲ^１９がそれぞれ独立に直鎖状または分岐鎖状のアルキレン基であって、Ｒ^１７の末端とＲ^１９の末端とが結合して環を形成していてもよい。］

[Wherein, R ¹⁷ and R ¹⁸ each independently represent a linear or branched alkyl group or a hydrogen atom, and R ¹⁹ represents a linear, branched or cyclic alkyl group. Alternatively, R ¹⁷ and R ¹⁹ may be each independently a linear or branched alkylene group, and the end of R ^{17 and} the end of R ¹⁹ may be bonded to form a ring. ]

In R ¹⁷ and R ¹⁸ , the alkyl group preferably has 1 to 15 carbon atoms, may be linear or branched, and is preferably an ethyl group or a methyl group, and most preferably a methyl group.
In particular, it is preferable that one of R ¹⁷ and R ¹⁸ is a hydrogen atom and the other is a methyl group.
R ¹⁹ is a linear, branched or cyclic alkyl group, preferably having 1 to 15 carbon atoms, and may be any of linear, branched or cyclic.
When R ¹⁹ is linear or branched, it preferably has 1 to 5 carbon atoms, more preferably an ethyl group or a methyl group, and most preferably an ethyl group.
When R ¹⁹ is cyclic, it preferably has 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, one or more polycycloalkanes such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane, which may or may not be substituted with a fluorine atom or a fluorinated alkyl group, are included. Examples include groups excluding hydrogen atoms. Specific examples thereof include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among them, a group obtained by removing one or more hydrogen atoms from adamantane is preferable.
In the above formula, R ¹⁷ and R ¹⁹ are each independently a linear or branched alkylene group (preferably an alkylene group having 1 to 5 carbon atoms), and the end of R ^{19 and} the end of R ¹⁷ And may be combined.
In this case, a cyclic group is formed by R ¹⁷ , R ¹⁹ , the oxygen atom to which R ¹⁹ is bonded, and the carbon atom to which the oxygen atom and R ¹⁷ are bonded. The cyclic group is preferably a 4-7 membered ring, and more preferably a 4-6 membered ring. Specific examples of the cyclic group include a tetrahydropyranyl group and a tetrahydrofuranyl group.

  As the structural unit (a1), one or more selected from the group consisting of structural units represented by the following general formula (a1-0-1) and structural units represented by the following general formula (a1-0-2): Is preferably used.

［式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基を示し；Ｘ^１は酸解離性溶解抑制基を示す。］

[Wherein, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; and X ¹ represents an acid dissociable, dissolution inhibiting group. ]

［式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基を示し；Ｘ^２は酸解離性溶解抑制基を示し；Ｙ^２はアルキレン基または脂肪族環式基を示す。］

[Wherein, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; X ² represents an acid dissociable, dissolution inhibiting group; Y ² represents an alkylene group or an aliphatic cyclic group. ]

In general formula (a1-0-1), the lower alkyl group or halogenated lower alkyl group for R is the same as the lower alkyl group or halogenated lower alkyl group that may be bonded to the α-position of the acrylate ester. .
X ¹ is not particularly limited as long as it is an acid dissociable, dissolution inhibiting group, and examples thereof include the above-described tertiary alkyl ester type acid dissociable, dissolution inhibiting group and acetal type acid dissociable, dissolution inhibiting group. And tertiary alkyl ester type acid dissociable, dissolution inhibiting groups are preferred.

In general formula (a1-0-2), R is the same as defined above.
X ² is the same as X ¹ in formula (a1-0-1).
Y ² is preferably an alkylene group having 1 to 10 carbon atoms or a divalent aliphatic cyclic group, and a group in which two or more hydrogen atoms are removed is used as the aliphatic cyclic group. Except for the above, the same “aliphatic cyclic group” as described above can be used.
When Y ² is an alkylene group having 1 to 10 carbon atoms, it is more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms. .
When Y ² is a divalent aliphatic cyclic group, a group in which two or more hydrogen atoms have been removed from cyclopentane, cyclohexane, norbornane, isobornane, adamantane, tricyclodecane, or tetracyclododecane is particularly preferable. .

  More specifically, examples of the structural unit (a1) include structural units represented by the following general formulas (a1-1) to (a1-4).

［上記式中、Ｘ’は第３級アルキルエステル型酸解離性溶解抑制基を表し、Ｙは炭素数１〜５の低級アルキル基、または脂肪族環式基を表し；ｎは０〜３の整数を表し；Ｙ^２はアルキレン基または脂肪族環式基を表し；Ｒは前記と同じであり、Ｒ^１’、Ｒ^２’はそれぞれ独立して水素原子または炭素数１〜５の低級アルキル基を表す。］

[In the above formula, X ′ represents a tertiary alkyl ester type acid dissociable, dissolution inhibiting group, Y represents a lower alkyl group having 1 to 5 carbon atoms, or an aliphatic cyclic group; Y ² represents an alkylene group or an aliphatic cyclic group; R is the same as defined above; and R ¹ ′ and R ² ′ each independently represent a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms. Represents. ]

Wherein, X 'include those of the same tertiary alkyl ester-type acid dissociable, dissolution inhibiting groups as those described above for X ^{1.
R 1 ', R 2',} n, as the Y, respectively, ^{R 1} in the general formula listed in the description of "acetal-type acid dissociable, dissolution inhibiting group" described above ^{(p1) ', R 2'} , n, Y The same thing is mentioned.
The Y ^2, the same groups as those described above for ^{Y 2} in the general formula (a1-0-2).

  Specific examples of the structural units represented by the general formulas (a1-1) to (a1-4) are shown below.

Among the above, the structural unit represented by the general formula (a1-1) is preferable, and specifically, (a1-1-1) to (a1-1-6) and (a1-1-35) to (a1). It is more preferable to use at least one selected from the group -1-41).
Furthermore, as the structural unit (a1), in particular, those represented by the following general formula (a1-1-01) including the structural units of the formula (a1-1-1) to the formula (a1-1-4) The following general formula (a1-1-02) including the structural units of formulas (a1-1-35) to (a1-1-41) is also preferable.

［式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基を示し、Ｒ^１１は低級アルキル基を示す。］

[Wherein, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, and R ¹¹ represents a lower alkyl group. ]

［式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基を示し、Ｒ^１２は低級アルキル基を示す。ｈは１〜３の整数を表す。］

[Wherein, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, and R ¹² represents a lower alkyl group. h represents an integer of 1 to 3. ]

In general formula (a1-1-01), R is the same as defined above.
The lower alkyl group for R ^{11 is the same as} the lower alkyl group for R, and is preferably a methyl group or an ethyl group.
In general formula (a1-1-02), R is the same as defined above.
The lower alkyl group for R ^{12 is the same as} the lower alkyl group for R, preferably a methyl group or an ethyl group, and most preferably an ethyl group. h is preferably 1 or 2, and most preferably 2.

As the structural unit (a1), one type may be used alone, or two or more types may be used in combination.
In the component (A1), the proportion of the structural unit (a1) is preferably 10 to 80 mol%, more preferably 20 to 70 mol%, and more preferably 25 to 50 mol% with respect to all the structural units constituting the component (A1). Is more preferable. By setting it to the lower limit value or more, a pattern can be easily obtained when the resist composition is used, and by setting it to the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a2)
The structural unit (a2) is a structural unit derived from an acrylate ester containing a lactone-containing cyclic group.
Here, the lactone-containing cyclic group refers to 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.
The lactone cyclic group of the structural unit (a2) has an affinity for a developer containing water, which increases the adhesion of the resist film to the substrate when the copolymer (A1) is used for forming a resist film. It is effective in improving the sex.

As the structural unit (a2), any unit can be used without any particular limitation.
Specifically, examples of the lactone-containing monocyclic group include groups in which one hydrogen atom has been removed from γ-butyrolactone. Examples of the lactone-containing polycyclic group include groups in which one hydrogen atom has been removed from a bicycloalkane, tricycloalkane, or tetracycloalkane having a lactone ring.

  More specifically, examples of the structural unit (a2) include structural units represented by general formulas (a2-1) to (a2-5) shown below.

［式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基であり、Ｒ’は水素原子、低級アルキル基、炭素数１〜５のアルコキシ基または−ＣＯＯＲ”であり、前記Ｒ”は水素原子、または炭素数１〜１５の直鎖状、分岐鎖状もしくは環状のアルキル基であり、ｍは０または１の整数であり、Ａ”は酸素原子もしくは硫黄原子を含んでいてもよい炭素数１〜５のアルキレン基、酸素原子または硫黄原子である。］

[Wherein, R is a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, R ′ is a hydrogen atom, a lower alkyl group, an alkoxy group having 1 to 5 carbon atoms, or —COOR ″, and the above R ″ is A hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 15 carbon atoms, m is an integer of 0 or 1, and A ″ is a carbon which may contain an oxygen atom or a sulfur atom. It is an alkylene group of formula 1 to 5, an oxygen atom or a sulfur atom.

R in the general formulas (a2-1) to (a2-5) is the same as R in the structural unit (a1).
The lower alkyl group for R ′ is the same as the lower alkyl group for R in the structural unit (a1).
When R ″ is a linear or branched alkyl group, it preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms.
When R ″ is a cyclic alkyl group, it preferably has 3 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, a fluorine atom or fluorine atom A group obtained by removing one or more hydrogen atoms from a polycycloalkane such as monocycloalkane, bicycloalkane, tricycloalkane, tetracycloalkane, etc., which may or may not be substituted with an alkyl group. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Can be mentioned.
In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.
Specific examples of the alkylene group having 1 to 5 carbon atoms that may contain an oxygen atom or sulfur atom of A ″ include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, —O—CH ₂ —. _{, -CH 2 -O-CH 2 -} , - S-CH 2 -, - CH 2 -S-CH 2 - , and the like.
Below, the specific structural unit of the said general formula (a2-1)-(a2-5) is illustrated.

  As the structural unit (a2), at least one selected from the group consisting of structural units represented by the general formulas (a2-1) to (a2-5) is preferable, and the general formulas (a2-1) to (a2) -3) At least 1 sort (s) selected from the group which consists of a structural unit represented by 3) is more preferable. Among them, chemical formulas (a2-1-1), (a2-1-2), (a2-2-1), (a2-2-2), (a2-2-9), (a2-2-10) ), (A2-3-1), (a2-3-2), (a2-3-9) and (a2-3-10) at least one selected from the group consisting of structural units It is preferable to use it.

As the structural unit (a2), one type may be used alone, or two or more types may be used in combination.
In the component (A1), the proportion of the structural unit (a2) is preferably 5 to 60 mol%, more preferably 10 to 50 mol%, based on the total of all the structural units constituting the component (A1). 50 mol% is more preferable. By setting it to the lower limit value or more, the effect of containing the structural unit (a2) can be sufficiently obtained, and by setting the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a3)
The structural unit (a3) is a structural unit derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group.
When the component (A1) has the structural unit (a3), the hydrophilicity of the component (A1) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved. Contributes to improvement.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom. A hydroxyl group is particularly preferable.
Examples of the aliphatic hydrocarbon group include a linear or branched hydrocarbon group having 1 to 10 carbon atoms (preferably an alkylene group) and a polycyclic aliphatic hydrocarbon group (polycyclic group). It is done. As the polycyclic group, for example, a resin for a resist composition for ArF excimer laser can be appropriately selected from among many proposed ones. The polycyclic group preferably has 7 to 30 carbon atoms.
Among them, a structural unit derived from an acrylate ester containing an aliphatic polycyclic group containing a hydroxyalkyl group in which a part of hydrogen atoms of a hydroxyl group, a cyano group, a carboxy group, or an alkyl group is substituted with a fluorine atom Is more preferable. Examples of the polycyclic group include groups in which two or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like. Specific examples include groups in which two or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among these polycyclic groups, there are groups in which two or more hydrogen atoms have been removed from adamantane, groups in which two or more hydrogen atoms have been removed from norbornane, and groups in which two or more hydrogen atoms have been removed from tetracyclododecane. Industrially preferable.

  The structural unit (a3) is derived from a hydroxyethyl ester of acrylic acid when the hydrocarbon group in the polar group-containing aliphatic hydrocarbon group is a linear or branched hydrocarbon group having 1 to 10 carbon atoms. When the hydrocarbon group is a polycyclic group, a structural unit represented by the following formula (a3-1), a structural unit represented by (a3-2), (a3-3) ) Is preferable.

[式中、Ｒは前記に同じであり、ｊは１〜３の整数であり、ｋは１〜３の整数であり、ｔ’は１〜３の整数であり、ｌは１〜５の整数であり、ｓは１〜３の整数である。]

[Wherein, R is the same as defined above, j is an integer of 1 to 3, k is an integer of 1 to 3, t ′ is an integer of 1 to 3, and l is an integer of 1 to 5] And s is an integer of 1 to 3. ]

In formula (a3-1), j is preferably 1 or 2, and more preferably 1. When j is 2, it is preferable that the hydroxyl group is bonded to the 3rd and 5th positions of the adamantyl group. When j is 1, it is preferable that the hydroxyl group is bonded to the 3-position of the adamantyl group.
j is preferably 1, and a hydroxyl group bonded to the 3-position of the adamantyl group is particularly preferred.
In formula (a3-2), k is preferably 1. The cyano group is preferably bonded to the 5th or 6th position of the norbornyl group.
In formula (a3-3), t ′ is preferably 1. l is preferably 1. s is preferably 1. These preferably have a 2-norbornyl group or a 3-norbornyl group bonded to the terminal of the carboxy group of acrylic acid. The fluorinated alkyl alcohol is preferably bonded to the 5th or 6th position of the norbornyl group.

As the structural unit (a3), one type may be used alone, or two or more types may be used in combination.
In the component (A1), the proportion of the structural unit (a3) is preferably 5 to 50 mol%, more preferably 5 to 40 mol%, and more preferably 5 to 25 mol% with respect to all the structural units constituting the component (A1). Is more preferable. By setting it to the lower limit value or more, the effect of containing the structural unit (a3) is sufficiently obtained, and by setting the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a4)
The component (A1) may contain other structural units (a4) other than the structural units (a1) to (a3) as long as the effects of the present invention are not impaired.
The structural unit (a4) is not particularly limited as long as it is another structural unit not classified into the above structural units (a1) to (a3), and for ArF excimer laser, for KrF excimer laser (preferably ArF excimer) A number of hitherto known materials can be used for resist resins such as lasers.
As the structural unit (a4), for example, a structural unit derived from an acrylate ester containing a non-acid-dissociable aliphatic polycyclic group is preferable. Examples of the polycyclic group include those exemplified in the case of the structural unit (a1), and for ArF excimer laser and KrF excimer laser (preferably for ArF excimer laser). A number of hitherto known materials can be used as the resin component of the resist composition.
In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, an isobornyl group, and a norbornyl group is preferable in terms of industrial availability. These polycyclic groups may have a linear or branched alkyl group having 1 to 5 carbon atoms as a substituent.
Specific examples of the structural unit (a4) include those represented by the following general formulas (a4-1) to (a4-5).

［式中、Ｒは前記と同じである。］

[Wherein, R is the same as defined above. ]

  When the structural unit (a4) is contained in the component (A1), the proportion of the structural unit (a4) in the component (A1) is 1 to 30 with respect to the total of all the structural units constituting the component (A1). Mol% is preferable and 10 to 20 mol% is more preferable.

In the component (A), as the copolymer (A1), one type may be used alone, or two or more types may be used in combination.
In the present invention, as the copolymer (A1), those containing the following combinations of structural units are particularly preferable.

［式中、Ｒは前記と同じであり、複数のＲはそれぞれ同じであっても異なっていてもよい。Ｒ^１０は低級アルキル基である。］

[Wherein, R is the same as defined above, and a plurality of R may be the same or different. R ¹⁰ is a lower alkyl group. ]

［式中、Ｒ、Ａ”は前記と同じであり、複数のＲはそれぞれ同じであっても異なっていてもよい。Ｒ^２０は低級アルキル基である。］

[Wherein, R and A ″ are the same as defined above, and the plurality of R may be the same or different. R ²⁰ is a lower alkyl group.]

In formula (A1-11), the lower alkyl group for R ^{10 is the same as} the lower alkyl group for R, preferably a methyl group or an ethyl group, and most preferably a methyl group.
In formula (A1-21), the lower alkyl group for R ^{20 is the same as} the lower alkyl group for R, preferably a methyl group or an ethyl group, and most preferably a methyl group.
In formula (A1-21), A ″ is the same as A ″ in formula (a2-2), and is preferably an oxygen atom, a methylene group, or an ethylene group.

  In the present invention, the component (A1) preferably contains a copolymer having the structural units (a1), (a2) and (a3). Examples of the copolymer include copolymers composed of the structural units (a1), (a2) and (a3), copolymers composed of the structural units (a1), (a2), (a3) and (a4). Can be mentioned.

The component (A1) can be obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN).
Further, for the component (A1), in the polymerization, a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH is used in combination, so that the terminal A —C (CF ₃ ) ₂ —OH group may be introduced into the. As described above, a copolymer introduced with a hydroxyalkyl group in which a part of hydrogen atoms of the alkyl group is substituted with a fluorine atom reduces development defects and LER (line edge roughness: uneven unevenness of line side walls). It is effective in reducing

The mass average molecular weight (Mw) (polystyrene conversion standard by gel permeation chromatography) of the component (A1) is not particularly limited, but is preferably 2000 to 50000, more preferably 3000 to 30000, and 5000 to 20000. Most preferred. When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist. When it is larger than the lower limit of this range, dry etching resistance and resist pattern cross-sectional shape are good.
Further, the dispersity (Mw / Mn) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5. In addition, Mn shows a number average molecular weight.

[(A2) component]
As the component (A2), a low molecular compound having a molecular weight of 500 or more and less than 2000 and having an acid dissociable, dissolution inhibiting group and a hydrophilic group as exemplified in the description of the component (A1) above is preferable. Specifically, a compound in which a part of hydrogen atoms of a hydroxyl group of a compound having a plurality of phenol skeletons is substituted with the acid dissociable, dissolution inhibiting group can be mentioned.
The component (A2) is, for example, a part of the hydrogen atom of the hydroxyl group of a low molecular weight phenol compound known as a sensitizer in a non-chemically amplified g-line or i-line resist or a heat resistance improver. Those substituted with a soluble dissolution inhibiting group are preferred and can be arbitrarily used.
Examples of such low molecular weight phenol compounds include bis (4-hydroxyphenyl) methane, bis (2,3,4-trihydroxyphenyl) methane, 2- (4-hydroxyphenyl) -2- (4′-hydroxyphenyl). ) Propane, 2- (2,3,4-trihydroxyphenyl) -2- (2 ′, 3 ′, 4′-trihydroxyphenyl) propane, tris (4-hydroxyphenyl) methane, bis (4-hydroxy-) 3,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-3,5-dimethylphenyl) -3, 4-dihydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -3,4-dihydroxyph Phenylmethane, bis (4-hydroxy-3-methylphenyl) -3,4-dihydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -4-hydroxyphenylmethane, bis (3-cyclohexyl- 4-hydroxy-6-methylphenyl) -3,4-dihydroxyphenylmethane, 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene, Examples include 2, 3, 4 nuclei of formalin condensates of phenols such as phenol, m-cresol, p-cresol or xylenol. Of course, it is not limited to these.
The acid dissociable, dissolution inhibiting group is not particularly limited, and examples thereof include those described above.

As the component (A), one type may be used alone, or two or more types may be used in combination.
In the resist composition of the present invention, the content of the component (A) may be adjusted according to the resist film thickness to be formed.

<(B) component>
(B) It does not specifically limit as a component, What has been proposed as an acid generator for chemical amplification type resists until now can be used. Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, poly (bissulfonyl) diazomethanes, and the like. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

  As the onium salt acid generator, for example, a compound represented by the following general formula (b-1) or (b-2) can be used.

[Wherein, R ¹ ″ to R ³ ″ and R ⁵ ″ to R ⁶ ″ each independently represents an aryl group or an alkyl group; among R ¹ ″ to R ³ ″ in formula (b-1), any two but may form a ring with the sulfur atom bonded to each other; R 4 ^"represents a linear, branched or cyclic alkyl group or fluorinated alkyl group; R ¹ At least one of “˜R ³ ” represents an aryl group, and at least one of R ⁵ ”to R ⁶ ” represents an aryl group.]

In formula (b-1), R ¹ ″ to R ³ ″ each independently represents an aryl group or an alkyl group. In addition, any two of R ¹ ″ to R ³ ″ in formula (b-1) may be bonded to each other to form a ring together with the sulfur atom in the formula.
Further, at least one of R ¹ ″ to R ³ ″ represents an aryl group. Of R ¹ ″ to R ³ ″, two or more are preferably aryl groups, and most preferably all R ¹ ″ to R ³ ″ are aryl groups.
The aryl group for R ¹ ″ to R ³ ″ is not particularly limited, and is, for example, an aryl group having 6 to 20 carbon atoms, in which part or all of the hydrogen atoms are alkyl groups, alkoxy groups It may or may not be substituted with a group, a halogen atom, a hydroxyl group or the like. The aryl group is preferably an aryl group having 6 to 10 carbon atoms because it can be synthesized at a low cost. Specific examples include a phenyl group and a naphthyl group.
The alkyl group that may be substituted for the hydrogen atom of the aryl group is preferably an alkyl group having 1 to 5 carbon atoms, and is a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group. Is most preferred.
As the alkoxy group that may be substituted for the hydrogen atom of the aryl group, an alkoxy group having 1 to 5 carbon atoms is preferable, and a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, Most preferred is a tert-butoxy group.
The alkoxy group that may be substituted for the hydrogen atom of the aryl group is preferably an alkoxy group having 1 to 5 carbon atoms, and most preferably a methoxy group or an ethoxy group.
The halogen atom that may substitute the hydrogen atom of the aryl group is preferably a fluorine atom.
The alkyl group for R 1 ^{"~R 3",} is not particularly limited, for example, linear C1-10, branched or cyclic alkyl group, and the like. It is preferable that it is C1-C5 from the point which is excellent in resolution. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a nonyl group, and a decanyl group. A methyl group is preferable because it is excellent in resolution and can be synthesized at low cost.
Among these, R ¹ ″ to R ³ ″ are most preferably a phenyl group or a naphthyl group, respectively.

When any two of R ¹ ″ to R ³ ″ in formula (b-1) are bonded to each other to form a ring together with the sulfur atom in the formula, a 3 to 10 membered ring including the sulfur atom is formed. It is preferable that a 5- to 7-membered ring is formed.
When any two of R ¹ ″ to R ³ ″ in formula (b-1) are bonded to each other to form a ring together with the sulfur atom in the formula, the remaining one may be an aryl group preferable. Examples of the aryl group include the same aryl groups as those described above for R ¹ ″ to R ³ ″.

R ⁴ ″ represents a linear, branched or cyclic alkyl group or a fluorinated alkyl group.
The linear or branched alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The cyclic alkyl group is a cyclic group as indicated by R ¹ ″ and preferably has 4 to 15 carbon atoms, more preferably 4 to 10 carbon atoms, and more preferably 6 carbon atoms. Most preferably, it is -10.
The fluorinated alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms. The fluorination rate of the fluorinated alkyl group (ratio of fluorine atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%. Particularly, all the hydrogen atoms are substituted with fluorine atoms. A fluorinated alkyl group (perfluoroalkyl group) is preferable because the strength of the acid is increased.
R ⁴ ″ is most preferably a linear or cyclic alkyl group or a fluorinated alkyl group.

In formula (b-2), R ⁵ ″ to R ⁶ ″ each independently represents an aryl group or an alkyl group. At least one of R ⁵ ″ to R ⁶ ″ represents an aryl group. All of R ⁵ ″ to R ⁶ ″ are preferably aryl groups.
As the aryl group for R ⁵ ″ to R ⁶ ″, the same as the aryl groups for R ¹ ″ to R ³ ″ can be used.
Examples of the alkyl group for R ⁵ ″ to R ⁶ ″ include the same as the alkyl group for R ¹ ″ to R ³ ″.
Among these, it is most preferable that all of R ⁵ ″ to R ⁶ ″ are phenyl groups.
"As ^{R 4} in the formula (b-1)" ^{R 4} in the In the formula (b-2) include the same as.

Specific examples of the onium salt acid generators represented by the formulas (b-1) and (b-2) include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium. Trifluoromethane sulfonate or nonafluorobutane sulfonate, triphenylsulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, tri (4-methylphenyl) sulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its Nonafluorobutanesulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethanesulfonate, its heptaful Lopropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of monophenyldimethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate; trifluoromethanesulfonate of diphenylmonomethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, (4-methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate , Trifluoromethanesulfonate of tri (4-tert-butyl) phenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of diphenyl (1- (4-methoxy) naphthyl) sulfonium, its heptafluoropropane Sulfonate or its nonafluorobutane sulfonate, di (1-naphthyl) phenyl sulphonium trifluoromethane sulphonate, its heptafluoropropane sulphonate or its nonafluorobutane sulphonate; 1-phenyltetrahydrothiophenium trifluoromethane sulphonate, its heptafluoropropane sulphonate Or nonafluorobutanesulfonate thereof; 1- (4-methylphenyl) ) Tetrahydrothiophenium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate; 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, its heptafluoropropane sulfonate 1- (4-methoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate; 1- (4-ethoxynaphthalene-1- Yl) tetrahydrothiophenium trifluoromethanesulfonate, its heptafluoropropanesulfonate or its nonaflu 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate; 1-phenyltetrahydrothiopyranium trifluoromethanesulfonate , Its heptafluoropropane sulfonate or its nonafluorobutane sulfonate; 1- (4-hydroxyphenyl) tetrahydrothiopyranium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate; 1- (3,5-dimethyl -4-Hydroxyphenyl) tetrahydrothiopyranium trifluoromethanesulfonate, its heptafluoropropanes Honeto or nonafluorobutanesulfonate; 1- (4-methylphenyl) trifluoromethanesulfonate tetrahydrothiophenium Pila chloride, heptafluoropropane sulfonate or its nonafluorobutane sulfonate, and the like.
In addition, onium salts in which the anion portion of these onium salts is replaced with methanesulfonate, n-propanesulfonate, n-butanesulfonate, or n-octanesulfonate can also be used.

  In addition, in the general formula (b-1) or (b-2), an onium salt-based acid generator in which the anion moiety is replaced with an anion moiety represented by the following general formula (b-3) or (b-4). Can also be used (the cation moiety is the same as (b-1) or (b-2)).

［式中、Ｘ”は、少なくとも１つの水素原子がフッ素原子で置換された炭素数２〜６のアルキレン基を表し；Ｙ”、Ｚ”は、それぞれ独立に、少なくとも１つの水素原子がフッ素原子で置換された炭素数１〜１０のアルキル基を表す。］

[Wherein X ″ represents an alkylene group having 2 to 6 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom; Y ″ and Z ″ each independently represent at least one hydrogen atom as a fluorine atom; Represents an alkyl group having 1 to 10 carbon atoms and substituted with

X ″ is a linear or branched alkylene group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkylene group has 2 to 6 carbon atoms, preferably 3 to 5 carbon atoms, Most preferably, it has 3 carbon atoms.
Y ″ and Z ″ are each independently a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkyl group has 1 to 10 carbon atoms, Has 1 to 7 carbon atoms, more preferably 1 to 3 carbon atoms.
The carbon number of the alkylene group of X ″ or the carbon number of the alkyl group of Y ″ and Z ″ is preferably as small as possible because the solubility in the resist solvent is good within the above carbon number range.
In addition, in the alkylene group of X ″ or the alkyl group of Y ″ and Z ″, the strength of the acid increases as the number of hydrogen atoms substituted with fluorine atoms increases, and high-energy light or electron beam of 200 nm or less The ratio of fluorine atoms in the alkylene group or alkyl group, that is, the fluorination rate is preferably 70 to 100%, more preferably 90 to 100%, and most preferably all. Are a perfluoroalkylene group or a perfluoroalkyl group in which a hydrogen atom is substituted with a fluorine atom.

  Moreover, the sulfonium salt which has a cation part represented by the following general formula (b-5) or (b-6) can also be used as an onium salt type | system | group acid generator.

［式中、Ｒ^４１〜Ｒ^４６はそれぞれ独立してアルキル基、アセチル基、アルコキシ基、カルボキシ基、水酸基またはヒドロキシアルキル基であり；ｎ_１〜ｎ_５はそれぞれ独立して０〜３の整数であり、ｎ_６は０〜２の整数である。］

[Wherein R ^{41 to} R ⁴⁶ are each independently an alkyl group, acetyl group, alkoxy group, carboxy group, hydroxyl group or hydroxyalkyl group; n _{1 to} n ₅ are each independently an integer of 0 to 3; There, _{n 6} is an integer of 0-2. ]

In R ^{41 to} R ⁴⁶ , the alkyl group is preferably an alkyl group having 1 to 5 carbon atoms, more preferably a linear or branched alkyl group, and a methyl group, an ethyl group, a propyl group, an isopropyl group, n A butyl group or a tert-butyl group is particularly preferable.
The alkoxy group is preferably an alkoxy group having 1 to 5 carbon atoms, more preferably a linear or branched alkoxy group, and particularly preferably a methoxy group or an ethoxy group.
The hydroxyalkyl group is preferably a group in which one or more hydrogen atoms in the alkyl group are substituted with a hydroxy group, and examples thereof include a hydroxymethyl group, a hydroxyethyl group, and a hydroxypropyl group.
When the symbols n _{1 to} n ₆ attached to R ^{41 to} R ⁴⁶ are integers of 2 or more, the plurality of R ^{41 to} R ⁴⁶ may be the same or different.
n ₁ is preferably 0 to 2, more preferably 0 or 1, and still more preferably 0.
n ₂ and n ₃ are preferably each independently 0 or 1, more preferably 0.
n ₄ is preferably 0 to 2, more preferably 0 or 1.
n ₅ is preferably 0 or 1, more preferably 0.
n ₆ is preferably 0 or 1, more preferably 1.

The anion part of the sulfonium salt having a cation part represented by the formula (b-5) or (b-6) is not particularly limited, and is the same as the anion part of the onium salt acid generators proposed so far. It may be a thing. Examples of the anion moiety include fluorinated alkyl sulfonate ions such as the anion moiety (R ^{4 ″} SO ₃ ⁻ ) of the onium salt acid generator represented by the general formula (b-1) or (b-2). An anion moiety represented by the general formula (b-3) or (b-4), etc. Among them, a fluorinated alkyl sulfonate ion is preferable, and a fluorinated alkyl sulfonic acid having 1 to 4 carbon atoms. Ion is more preferable, and linear perfluoroalkylsulfonic acid ions having 1 to 4 carbon atoms are particularly preferable, and specific examples thereof include trifluoromethylsulfonic acid ions, heptafluoro-n-propylsulfonic acid ions, and nonafluoro-n. -Butyl sulfonate ion etc. are mentioned.

  In this specification, the oxime sulfonate acid generator is a compound having at least one group represented by the following general formula (B-1), and has a property of generating an acid upon irradiation with radiation. is there. Such oxime sulfonate-based acid generators are frequently used for chemically amplified resist compositions, and can be arbitrarily selected and used.

［式（Ｂ−１）中、Ｒ^３１、Ｒ^３２はそれぞれ独立に有機基を表す。］

[In formula (B-1), R ³¹ and R ³² each independently represents an organic group. ]

The organic groups of R ³¹ and R ³² are groups containing carbon atoms, and atoms other than carbon atoms (for example, hydrogen atoms, oxygen atoms, nitrogen atoms, sulfur atoms, halogen atoms (fluorine atoms, chlorine atoms, etc.), etc.) You may have.
As the organic group for R ^31, a linear, branched, or cyclic alkyl group or aryl group is preferable. These alkyl groups and aryl groups may have a substituent. There is no restriction | limiting in particular as this substituent, For example, a fluorine atom, a C1-C6 linear, branched or cyclic alkyl group etc. are mentioned. Here, “having a substituent” means that part or all of the hydrogen atoms of the alkyl group or aryl group are substituted with a substituent.
As an alkyl group, C1-C20 is preferable, C1-C10 is more preferable, C1-C8 is more preferable, C1-C6 is especially preferable, and C1-C4 is the most preferable. As the alkyl group, a partially or completely halogenated alkyl group (hereinafter sometimes referred to as a halogenated alkyl group) is particularly preferable. The partially halogenated alkyl group means an alkyl group in which a part of hydrogen atoms is substituted with a halogen atom, and the fully halogenated alkyl group means that all of the hydrogen atoms are halogen atoms. Means an alkyl group substituted with Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable. That is, the halogenated alkyl group is preferably a fluorinated alkyl group.
The aryl group preferably has 4 to 20 carbon atoms, more preferably 4 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms. As the aryl group, a partially or completely halogenated aryl group is particularly preferable. The partially halogenated aryl group means an aryl group in which a part of hydrogen atoms is substituted with a halogen atom, and the fully halogenated aryl group means that all of the hydrogen atoms are halogen atoms. Means an aryl group substituted with.
R ³¹ is particularly preferably an alkyl group having 1 to 4 carbon atoms or a fluorinated alkyl group having 1 to 4 carbon atoms which has no substituent.

As the organic group for R ^32, a linear, branched, or cyclic alkyl group, aryl group, or cyano group is preferable. As the alkyl group and aryl group for R ^32, the same alkyl groups and aryl groups as those described above for R ³¹ can be used.
R ³² is particularly preferably a cyano group, an alkyl group having 1 to 8 carbon atoms having no substituent, or a fluorinated alkyl group having 1 to 8 carbon atoms.

  More preferable examples of the oxime sulfonate-based acid generator include compounds represented by the following general formula (B-2) or (B-3).

［式（Ｂ−２）中、Ｒ^３３は、シアノ基、置換基を有さないアルキル基またはハロゲン化アルキル基である。Ｒ^３４はアリール基である。Ｒ^３５は置換基を有さないアルキル基またはハロゲン化アルキル基である。］

[In Formula (B-2), R ³³ represents a cyano group, an alkyl group having no substituent, or a halogenated alkyl group. R ³⁴ is an aryl group. R ³⁵ represents an alkyl group having no substituent or a halogenated alkyl group. ]

［式（Ｂ−３）中、Ｒ^３６はシアノ基、置換基を有さないアルキル基またはハロゲン化アルキル基である。Ｒ^３７は２または３価の芳香族炭化水素基である。Ｒ^３８は置換基を有さないアルキル基またはハロゲン化アルキル基である。ｐ”は２または３である。］

[In Formula (B-3), R ³⁶ represents a cyano group, an alkyl group having no substituent, or a halogenated alkyl group. R ³⁷ is a divalent or trivalent aromatic hydrocarbon group. ^R38 is an alkyl group having no substituent or a halogenated alkyl group. p ″ is 2 or 3.]

In the general formula (B-2), the alkyl group or halogenated alkyl group having no substituent of R ³³ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and carbon atoms. Numbers 1 to 6 are most preferable.
R ³³ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group.
The fluorinated alkyl group for R ³³ is preferably such that the hydrogen atom of the alkyl group is 50% or more fluorinated, more preferably 70% or more fluorinated, and 90% or more fluorinated. Particularly preferred.

As the aryl group of R ³⁴ , one hydrogen atom is removed from an aromatic hydrocarbon ring such as a phenyl group, a biphenyl group, a fluorenyl group, a naphthyl group, an anthryl group, or a phenanthryl group. And a heteroaryl group in which a part of carbon atoms constituting the ring of these groups is substituted with a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. Among these, a fluorenyl group is preferable.
The aryl group of R ³⁴ may have a substituent such as an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, or an alkoxy group. The alkyl group or halogenated alkyl group in the substituent preferably has 1 to 8 carbon atoms, and more preferably 1 to 4 carbon atoms. The halogenated alkyl group is preferably a fluorinated alkyl group.

The alkyl group or halogenated alkyl group having no substituent for R ³⁵ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 6 carbon atoms.
R ³⁵ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group.
The fluorinated alkyl group for R ³⁵ is preferably such that the hydrogen atom of the alkyl group is 50% or more fluorinated, more preferably 70% or more fluorinated, and 90% or more fluorinated. Particularly preferred is the strength of the acid generated. Most preferably, it is a fully fluorinated alkyl group in which a hydrogen atom is 100% fluorine-substituted.

In the general formula (B-3), the alkyl group or halogenated alkyl group having no substituent for R ³⁶ is the same as the alkyl group or halogenated alkyl group having no substituent for R ^33. Is mentioned.
Examples of the divalent or trivalent aromatic hydrocarbon group for R ³⁷ include groups obtained by further removing one or two hydrogen atoms from the aryl group for R ³⁴ .
Examples of the alkyl group or halogenated alkyl group having no substituent of R ³⁸ include the same alkyl groups or halogenated alkyl groups as those having no substituent of R ³⁵ .
p ″ is preferably 2.

Specific examples of the oxime sulfonate acid generator include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4-nitrobenzenesulfonyloxy). Imino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzylcyanide, α- (benzenesulfonyl) Oxyimino) -2,4-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzyl cyanide, α- ( 2-Chlorobenzenesulfonyloxyimino) 4-methoxybenzylcyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzylcyanide, α-[(p-toluenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1-cyclo Pentenyl acetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctene Acetonitrile, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propyl Sulfonyloxyimino) -propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- ( Ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclope N-tenyl acetonitrile, α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile , Α- (n-butylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoro Methylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p- Butoxy phenylacetonitrile, alpha-(propylsulfonyl oxyimino)-p-methylphenyl acetonitrile, alpha-like (methylsulfonyloxyimino)-p-bromophenyl acetonitrile.
Also, an oxime sulfonate-based acid generator disclosed in JP-A-9-208554 (paragraphs [0012] to [0014] [chemical formula 18] to [chemical formula 19]), WO 2004 / 074242A2 (pages 65 to 85). The oxime sulfonate acid generators disclosed in Examples 1 to 40) of No. 1 can also be suitably used.
Moreover, the following can be illustrated as a suitable thing.

Among diazomethane acid generators, specific examples of bisalkyl or bisarylsulfonyldiazomethanes include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, Examples include bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenylsulfonyl) diazomethane, and the like.
Further, diazomethane acid generators disclosed in JP-A-11-035551, JP-A-11-035552, and JP-A-11-035573 can also be suitably used.
Examples of poly (bissulfonyl) diazomethanes include 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane and 1,4-bis (phenylsulfonyldiazo) disclosed in JP-A-11-322707. Methylsulfonyl) butane, 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane, 1,10-bis (phenylsulfonyldiazomethylsulfonyl) decane, 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane, 1,3 -Bis (cyclohexylsulfonyldiazomethylsulfonyl) propane, 1,6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane, 1,10-bis (cyclohexylsulfonyldiazomethylsulfonyl) decane, etc. Door can be.

(B) As a component, these acid generators may be used individually by 1 type, and may be used in combination of 2 or more type.
In the present invention, as the component (B), it is preferable to use an onium salt acid generator having an anion of a fluorinated alkyl sulfonate ion which may have a substituent.
The content of the component (B) in the resist composition for immersion exposure according to the present invention is preferably 0.5 to 50 parts by mass and more preferably 1 to 30 parts by mass with respect to 100 parts by mass of the component (A). By setting it within the above range, pattern formation is sufficiently performed. Moreover, since a uniform solution is obtained and storage stability becomes favorable, it is preferable.

<(C) component>
Component (C) is the fluorine-containing copolymer (C) of the present invention described above.
As the component (C), one type may be used alone, or two or more types may be used in combination.
The content of the component (C) in the resist composition for immersion exposure according to the present invention is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass with respect to 100 parts by mass of the component (A). 1 to 15 parts by mass is more preferable. When it is at least the lower limit of the above range, the hydrophobicity of the resist film formed using the resist composition for immersion exposure is improved, and the hydrophobicity suitable for immersion exposure is obtained. If so, the lithography properties are improved.

<Optional component>
In the resist composition for immersion exposure according to the present invention, a nitrogen-containing organic compound (D) (hereinafter referred to as the (D) component) is further added as an optional component in order to improve the resist pattern shape, the stability over time. .) Can be blended.
Since a wide variety of components (D) have already been proposed, any known one may be used. Among them, aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are used. preferable. Here, the aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon atoms.
Examples of the aliphatic amine include an amine (alkyl amine or alkyl alcohol amine) or a cyclic amine in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms.
Specific examples of alkylamines and alkyl alcohol amines include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di- -Dialkylamines such as n-heptylamine, di-n-octylamine, dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine , Tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n-dodecylamine, etc .; diethanolamine, triethanolamine, diisopropanolamine Triisopropanolamine, di -n- octanol amines, alkyl alcohol amines tri -n- octanol amine. Among these, a trialkylamine having 5 to 10 carbon atoms is preferable, and tri-n-pentylamine is most preferable.
Examples of the cyclic amine include heterocyclic compounds containing a nitrogen atom as a hetero atom. The heterocyclic compound may be monocyclic (aliphatic monocyclic amine) or polycyclic (aliphatic polycyclic amine).
Specific examples of the aliphatic monocyclic amine include piperidine and piperazine.
As the aliphatic polycyclic amine, those having 6 to 10 carbon atoms are preferable. Specifically, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5. 4.0] -7-undecene, hexamethylenetetramine, 1,4-diazabicyclo [2.2.2] octane, and the like.
These may be used alone or in combination of two or more.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

In the resist composition for immersion exposure according to the present invention, an organic carboxylic acid, a phosphorus oxoacid, and a phosphorus oxoacid and At least one compound (E) selected from the group consisting of derivatives thereof (hereinafter referred to as component (E)) can be contained.
As the organic carboxylic acid, for example, acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Examples of phosphorus oxo acids and derivatives thereof include phosphoric acid, phosphonic acid, phosphinic acid and the like, and among these, phosphonic acid is particularly preferable.
Examples of the oxo acid derivative of phosphorus include esters in which the hydrogen atom of the oxo acid is substituted with a hydrocarbon group, and the hydrocarbon group includes an alkyl group having 1 to 5 carbon atoms and 6 to 6 carbon atoms. 15 aryl groups and the like.
Examples of phosphoric acid derivatives include phosphoric acid esters such as di-n-butyl phosphate and diphenyl phosphate.
Examples of phosphonic acid derivatives include phosphonic acid esters such as phosphonic acid dimethyl ester, phosphonic acid-di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, and phosphonic acid dibenzyl ester.
Examples of phosphinic acid derivatives include phosphinic acid esters such as phenylphosphinic acid.
(E) A component may be used individually by 1 type and may use 2 or more types together.
(E) A component is used in 0.01-5.0 mass parts normally with respect to 100 mass parts of (A) component.

  The resist composition for immersion exposure according to the present invention further contains miscible additives as desired, for example, additional resins for improving the performance of the resist film, surfactants for improving coating properties, and dissolution inhibition. An agent, a plasticizer, a stabilizer, a colorant, an antihalation agent, a dye, and the like can be appropriately added and contained.

<Organic solvent (S)>
The resist composition for immersion exposure according to the present invention can be produced by dissolving a material in an organic solvent (hereinafter sometimes referred to as (S) component).
As the component (S), any component can be used as long as it can dissolve each component to be used to form a uniform solution. Conventionally, any one of known solvents for chemically amplified resists can be used. Two or more types can be appropriately selected and used.
For example, lactones such as γ-butyrolactone; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone, methyl isopentyl ketone, and 2-heptanone; many such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol Monohydric alcohols: compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate or dipropylene glycol monoacetate, monomethyl ether, monoethyl of the polyhydric alcohols or the compound having an ester bond Ether alkyl such as ether, monopropyl ether, monobutyl ether or monophenyl ether Derivatives of polyhydric alcohols such as compounds having a propylene glycol monomethyl ether acetate (PGMEA) or propylene glycol monomethyl ether (PGME) among these]; cyclic ethers such as dioxane, methyl lactate, Esters such as ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate; anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, Aromatic organics such as dibenzyl ether, phenetol, butyl phenyl ether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, mesitylene A solvent etc. can be mentioned.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
Among these, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and EL are preferable.
Moreover, the mixed solvent which mixed PGMEA and the polar solvent is also preferable. The blending ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. Moreover, when mix | blending PGME as a polar solvent, the mass ratio of PGMEA: PGME becomes like this. Preferably it is 1: 9-9: 1, More preferably, it is 2: 8-8: 2, More preferably, it is 3: 7-7: 3.
In addition, as the component (S), a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.
The amount of the component (S) used is not particularly limited, but is a concentration that can be applied to a substrate or the like, and is appropriately set according to the coating film thickness. In general, the solid content concentration of the resist composition is 2 -20% by mass, preferably 5-15% by mass.

  The dissolution of the material in the component (S) can be carried out, for example, by simply mixing and stirring the above-mentioned components by a usual method, and if necessary, a disperser such as a dissolver, a homogenizer, or a three roll mill. You may use and disperse and mix. Moreover, after mixing, you may further filter using a mesh, a membrane filter, etc.

The resist composition for immersion exposure according to the present invention has good lithography characteristics, which are characteristics required for a resist composition used for immersion exposure, and characteristics (hydrophobic hydrophobicity) suitable for immersion exposure. For this reason, it is preferably used for immersion exposure.
That is, the resist film formed by using the resist composition for immersion exposure according to the present invention is the above-mentioned (C) which is the fluorine-containing copolymer (C) according to the present invention having the structural units (c1) and (c2). Contains ingredients.
As described above, the structural unit (c1) and (c2) are each comprises a fluorine atom, and a base dissociable group ^-Q 2 -R ² bonded to hydrophilic groups. Thus, (C) component, which has a high hydrophobicity because it has a fluorine atom, by having -Q ² -R ^2, have the property of hydrophilicity is increased under basic conditions. This is because —R ² is dissociated by the action of a base (alkaline developer) to produce a hydrophilic group (—Q ² H).
Therefore, the resist film formed using the resist composition for immersion exposure according to the present invention in which the component (C) is blended with the component (A) and the component (B) is contacted with an alkali developer (for example, While having a high hydrophobicity during immersion exposure, the hydrophilicity is increased by contact with an alkaline developer.
Thus, since the hydrophobicity at the time of immersion exposure is high, the resist film formed using the resist composition for immersion exposure according to the present invention is a scan type liquid as described in Non-Patent Document 1. It is very excellent in water followability required for immersion exposure using an immersion exposure machine.
Moreover, since hydrophilicity increases at the time of alkali development, according to the resist composition for immersion exposure of the present invention, defects in immersion exposure can be effectively reduced. That is, in the immersion exposure, when immersion exposure is performed on the resist film, the solubility of the exposed portion in the alkaline developer changes. For example, in the case of the positive type, the solubility of the exposed portion in the alkaline developer increases, and in the case of the negative type, the solubility of the exposed portion in the alkaline developer decreases. Then, by performing alkali development, in the case of the positive type, the exposed portion is removed, and in the case of the negative type, the unexposed portion is removed to form a resist pattern.
At this time, on the surface of the resist film where the radiation is not irradiated by immersion exposure (for example, the unexposed portion in the case of a positive type), after development, a defect due to the influence of an immersion medium such as water (watermark defect etc.) However, the resist film formed using the resist composition for immersion exposure according to the present invention has increased hydrophilicity during development, so that the occurrence of defects can be reduced.
In the resist composition for immersion exposure according to the present invention, as the component (C), by including both the structural units (c1) and (c2), the hydrophilicity at the time of alkali development is greater than the case where each of them is included alone. The defect in the immersion exposure can be more effectively reduced.

Moreover, by using the resist composition for immersion exposure of the present invention, substance elution from the resist film during immersion exposure can be suppressed.
That is, as described above, the immersion exposure is performed by exposing the portion between the lens and the resist film on the wafer, which is conventionally filled with an inert gas such as air or nitrogen, at a time higher than the refractive index of air. This is a method including a step of performing exposure (immersion exposure) in a state filled with a solvent (immersion medium) having a large refractive index. In immersion exposure, when the resist film and the immersion solvent come into contact with each other, elution (substance elution) of substances ((B) component, (D) component, etc.) in the resist film into the immersion solvent occurs. Substance elution causes phenomena such as alteration of the resist layer and change in the refractive index of the immersion solvent, thereby deteriorating lithography characteristics.
The amount of this substance elution is affected by the characteristics of the resist film surface (for example, hydrophilicity / hydrophobicity). Therefore, for example, it is presumed that elution of the substance is reduced by increasing the hydrophobicity of the resist film surface.
Since the resist film formed using the resist composition for immersion exposure of the present invention contains a component (C) having a fluorine atom, exposure and development can be performed as compared with the case where the component (C) is not included. High hydrophobicity before performing. Therefore, according to the resist composition for immersion exposure of the present invention, substance elution during immersion exposure can be suppressed.
Since elution of the substance can be suppressed, the use of the resist composition for immersion exposure according to the present invention can suppress the alteration of the resist film and the change in the refractive index of the immersion solvent in the immersion exposure. A resist pattern having a good shape and the like can be formed by suppressing fluctuations in the refractive index of the immersion solvent. Further, the contamination of the lens of the exposure apparatus can be reduced, and therefore, it is not necessary to take protective measures against these, and it is possible to contribute to the simplification of the process and the exposure apparatus.
In addition, since the resist film formed from the resist composition for immersion exposure according to the present invention hardly swells with water, a fine resist pattern can be formed with high accuracy.
Furthermore, the resist composition for immersion exposure of the present invention has good lithography properties such as sensitivity, resolution and etching resistance, and forms a resist pattern without any practical problems when used as a resist in immersion exposure. it can. For example, by using the resist composition for immersion exposure according to the present invention, a fine resist pattern having a dimension of 120 nm or less can be formed.

The hydrophobicity of the resist film includes the contact angle with water, for example, the static contact angle (the angle between the surface of the water droplet on the resist film in the horizontal state and the resist film surface), and the dynamic contact angle (the tilted resist film). The contact angle when the water droplet starts to fall (fall angle), the contact angle at the front end point in the water drop direction (advance angle), the contact angle at the rear end point in the fall direction (retreat angle).) It can evaluate by measuring etc. For example, the higher the hydrophobicity of the resist film, the larger the static contact angle, the advancing angle, and the receding angle, while the smaller the falling angle.
Here, as shown in FIG. 1, when the plane 2 on which the droplet 1 is placed is gradually tilted, the advancing angle starts to move (drop) on the plane 2 when the plane 1 is gradually inclined. Is the angle θ ₁ formed by the surface of the droplet at the lower end 1 a of the droplet 1 and the plane 2. At this time (when the droplet 1 starts to move (drop) on the plane 2), an angle θ2 formed by the droplet surface at the upper end 1b of the droplet 1 and the plane ₂ is a receding angle, The inclination angle θ _{3 of the} plane 2 is the falling angle.
In this specification, the advancing angle, the receding angle, and the falling angle are measured as follows.
First, a resist composition solution is spin-coated on a silicon substrate, and then heated at 110 ° C. for 60 seconds to form a resist film.
Next, with respect to the resist film, DROP MASTER-700 (product name, manufactured by Kyowa Interface Science Co., Ltd.), AUTO SLIDING ANGLE: SA-30DM (product name, manufactured by Kyowa Interface Science Co., Ltd.), AUTO DISPENSER: AD-31 ( It can be measured using a commercially available measuring device such as a product name (manufactured by Kyowa Interface Science Co., Ltd.).

In the resist composition for immersion exposure according to the present invention, the measured value of the receding angle before exposure and development in a resist film obtained using the resist composition is preferably 50 degrees or more, and 50 to 150 degrees. More preferably, it is 50 to 130 degrees, particularly preferably 53 to 100 degrees. When the receding angle is at least the lower limit degree, the substance elution suppressing effect during immersion exposure is improved. The reason for this is not clear, but one of the main factors may be related to the hydrophobicity of the resist film. In other words, since the aqueous immersion medium is an aqueous medium such as water, it is highly hydrophobic, so that the immersion medium is quickly removed from the resist film surface when the immersion medium is removed after immersion exposure. It is presumed that the fact that it can be removed is affected. Further, when the receding angle is not more than the upper limit value, the lithography characteristics and the like are good.
For the same reason, the resist composition for immersion exposure of the present invention has a measured value of a static contact angle of 60 degrees or more before performing exposure and development in a resist film obtained using the resist composition. Is preferable, it is more preferable that it is 63-95 degree | times, and it is especially preferable that it is 65-95 degree | times.
Moreover, the resist composition for immersion exposure according to the present invention preferably has a measured value of a falling angle of 36 degrees or less before performing exposure and development in a resist film obtained using the resist composition. It is more preferably 36 degrees, particularly preferably 7 to 30 degrees, and most preferably 14 to 27 degrees. When the falling angle is less than or equal to the upper limit value, the substance elution suppression effect during immersion exposure is improved. Further, when the sliding angle is at least the lower limit value, the lithography properties and the like are good.
The above-mentioned various angles (dynamic contact angle (advance angle, receding angle, sliding angle, etc.), static contact angle) are determined depending on the composition of the resist composition for immersion exposure, for example, the type and composition of component (C). The amount can be adjusted by adjusting the type of component (A). For example, as the content of the component (C) increases, the hydrophobicity of the resulting resist composition increases, the advancing angle, the receding angle, and the static contact angle increase, and the sliding angle decreases.

  As described above, the resist composition for immersion exposure according to the present invention is suitably used for immersion exposure because it sufficiently has various characteristics required for resist materials in immersion exposure.

≪Resist pattern formation method≫
The resist pattern forming method of the present invention includes a step of forming a resist film on a support using the resist composition for immersion exposure according to the present invention, a step of immersing the resist film, and an alkali treatment of the resist film. And developing to form a resist pattern.

A preferred example of the method for forming a resist pattern of the present invention is shown below.
First, after applying the resist composition for immersion exposure of the present invention on a support with a spinner or the like, a resist film is formed by performing pre-baking (post-apply baking (PAB) treatment).

The support is not particularly limited, and a conventionally known one can be used, and examples thereof include a substrate for electronic components and a substrate on which a predetermined wiring pattern is formed. More specifically, a silicon substrate, a metal substrate such as copper, chromium, iron, and aluminum, a glass substrate, and the like can be given. As a material for the wiring pattern, for example, copper, aluminum, nickel, gold or the like can be used.
Further, the support may be a substrate in which an inorganic and / or organic film is provided on the above-described substrate. An inorganic antireflection film (inorganic BARC) is an example of the inorganic film. Examples of the organic film include organic films such as an organic antireflection film (organic BARC) and a lower organic film in a multilayer resist method.
Here, the multilayer resist method is a method in which at least one organic film (lower organic film) and at least one resist film (upper resist film) are provided on a substrate, and the resist pattern formed on the upper resist film is used as a mask. This is a method of patterning a lower organic film, and it is said that a pattern with a high aspect ratio can be formed. That is, according to the multilayer resist method, the required thickness can be secured by the lower organic film, so that the resist film can be thinned and a fine pattern with a high aspect ratio can be formed.
In the multilayer resist method, basically, a method of forming a two-layer structure of an upper resist film and a lower organic film (two-layer resist method), and one or more intermediate layers between the upper resist film and the lower organic film And a method of forming a multilayer structure of three or more layers (metal thin film etc.) (three-layer resist method).

  After the resist film is formed, an organic antireflection film may be further provided on the resist film to form a three-layer laminate including a support, a resist film, and an antireflection film. The antireflection film provided on the resist film is preferably soluble in an alkali developer.

  The steps so far can be performed using a known method. The operating conditions and the like are preferably set as appropriate according to the composition and characteristics of the resist composition for immersion exposure to be used.

Next, liquid immersion lithography is selectively performed on the resist film obtained above through a desired mask pattern. At this time, the space between the resist film and the lens at the lowest position of the exposure apparatus is previously filled with a solvent (immersion medium) having a refractive index larger than that of air, and exposure (immersion exposure) is performed in this state.
The wavelength used for the exposure is not particularly limited, and can be performed using radiation such as an ArF excimer laser, a KrF excimer laser, or an F ₂ laser. The resist composition according to the present invention is effective for a KrF or ArF excimer laser, particularly an ArF excimer laser.

As the immersion medium, a solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film formed using the resist composition for immersion exposure of the present invention is preferable. The refractive index of such a solvent is not particularly limited as long as it is within the above range.
Examples of the solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film include water, a fluorine-based inert liquid, a silicon-based solvent, and a hydrocarbon-based solvent.
Specific examples of the fluorinated inert liquid include fluorinated compounds such as C ₃ HCl ₂ F ₅ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , and C ₅ H ₃ F ₇ as main components. Examples thereof include liquids, and those having a boiling point of 70 to 180 ° C are preferable, and those having a boiling point of 80 to 160 ° C are more preferable. It is preferable that the fluorine-based inert liquid has a boiling point in the above range since the medium used for immersion can be removed by a simple method after the exposure is completed.
As the fluorine-based inert liquid, a perfluoroalkyl compound in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms is particularly preferable. Specific examples of the perfluoroalkyl compound include a perfluoroalkyl ether compound and a perfluoroalkylamine compound.
More specifically, examples of the perfluoroalkyl ether compound include perfluoro (2-butyl-tetrahydrofuran) (boiling point 102 ° C.). Examples of the perfluoroalkylamine compound include perfluorotributylamine ( Boiling point of 174 ° C.).
The resist composition for immersion exposure according to the present invention is not particularly adversely affected by water, and is excellent in lithography properties such as sensitivity and resist pattern shape. Therefore, in the present invention, water is preferably used as the immersion medium. . Water is also preferable from the viewpoints of cost, safety, environmental problems, and versatility.

  Next, after the immersion exposure step is completed, post-exposure heating (post-exposure baking (PEB)) is performed, and subsequently, development processing is performed using an alkaline developer composed of an alkaline aqueous solution. And preferably, water rinsing is performed using pure water. The water rinse is performed, for example, by dropping or spraying water on the surface of the support while rotating the support to wash away the developer on the support and the resist composition for immersion exposure dissolved by the developer. Can be implemented. Then, drying is performed to obtain a resist pattern in which the resist film (the coating film of the resist composition for immersion exposure) is patterned into a shape corresponding to the mask pattern.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.
In the following examples, the mass average molecular weight (hereinafter abbreviated as molecular weight) is the standard polystyrene equivalent mass average molecular weight determined by GPC measurement, and the polymer composition is the ratio (molar ratio) of each structural unit in the structural formula. ).

(Reference Example 1)
4.76 g (29.41 mmol) of [Compound 1] and 20.00 g (117.65 mmol) of [Compound 2] were dissolved in 37.14 g of ethyl lactate. To this solution, 7.34 mmol of polymerization initiator V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) was added and dissolved. This solution was subjected to a polymerization reaction at 80 ° C. for 6 hours in a nitrogen atmosphere. After completion of the reaction, the reaction solution was cooled to room temperature. Thereafter, an aqueous hydrazine solution was added to hydrolyze the acetoxy group, and then dropped into a large amount of water, washed and neutralized, and the resulting precipitate was filtered. Next, the operation of washing the filtrate with a large amount of water / methanol solution was repeated twice, and the resulting wet powder was collected and dried under reduced pressure to obtain 13 g of the desired [Polymer Compound 1]. Obtained. The polymer composition ratio determined from 600 MHz 13C-NMR was 1 / m = 20/80 (molar ratio).

[Example 1]
Under a nitrogen atmosphere at 0 ° C., 1.2 g (9.5 mmol) of 3,3,3-trifluoropropionic acid, 1.8 g (9.5 mmol) of ethyldiisopropylaminocarbodiimide (EDCI) hydrochloride, dimethylaminopyridine (DMAP) 1.0 g (corresponding to 6.3 mmol) of [Polymer Compound 1] was added to 15 ml of 0.04 g (0.3 mmol) in tetrahydrofuran (THF), and the mixture was returned to room temperature and stirred for 3 hours. The reaction solution was cooled to 0 ° C., and water was added to stop the reaction. The obtained organic layer was washed with water three times, and the solvent was distilled off under reduced pressure. 1.2 g of the desired [fluorinated copolymer 1] was obtained as a colorless solid by a reprecipitation operation in which a THF solution of the obtained crude product was dropped into heptane (yield 71%). About this [fluorinated copolymer 1], the introduction of —CO—CH ₂ —CF ₃ was confirmed by ¹³ C-NMR, and the introduction rate was> 99%. Moreover, the molecular weight of [fluorinated copolymer 1] was 8,700, and the degree of dispersion was 1.34.

[Example 2 and Comparative Example 1]
Each component shown in the following Table 1 was mixed and dissolved to prepare a resist composition.

Each abbreviation in Table 1 indicates the following.
(A) -1: a copolymer represented by the following chemical formula (A) -1 (molecular weight: 7,000, dispersity 1.8). In the formula, the numerical value on the lower right of () indicates the ratio (mol%) of each structural unit.
(B) -1: (4-methylphenyl) diphenylsulfonium nonafluoro-n-butanesulfonate.
(C) -1: [fluorinated copolymer 1] synthesized in Example 1.
(D) -1: tri-n-pentylamine.
(S) -1: PGMEA / PGME = 6/4 (mass ratio) mixed solvent.

Next, each of the resist compositions of Example 2 and Comparative Example 1 was applied onto an 8-inch silicon wafer using a spinner, pre-baked on a hot plate at 110 ° C. for 60 seconds, and dried. A 120 nm resist film was formed.
Water was dropped on the surface of the resist film (resist film before exposure), and the contact angle (static contact angle) was measured using DROP MASTER-700 (product name, manufactured by Kyowa Interface Science Co., Ltd.). (Measurement of contact angle: 2 μL of water). This measured value was defined as “contact angle after coating (°)”.
The wafer after contact angle measurement was developed with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution at 23 ° C. for 30 seconds or 60 seconds, and then rinsed with pure water for 15 seconds. Thereafter, the contact angle was measured in the same manner as described above. These measured values were defined as “30 s contact angle after development (°)” and “60 s contact angle after development (°)”, respectively. These results are shown in Table 2.

As shown in the above results, the resist film formed using the resist composition of Example 2 blended with [fluorinated copolymer 1] has a contact angle after development rather than a contact angle before development. It was low. That is, these resist films have higher hydrophilicity after development than before development.
That is, the resist composition of Example 2 was hydrophobic during immersion exposure and hydrophilic during development. This is presumably because —CO—CH ₂ —CF _{3 in} [fluorinated copolymer 1] was dissociated by the action of the alkali developer to produce —OH, and the solubility in the alkali developer was increased. .
In addition, the resist composition of Example 2 has a higher contact angle before development than a resist film formed using the resist composition of Comparative Example 1 in which [Fluoropolymer 1] is not blended, The contact angle after development was low. From this result, by adding [Fluoropolymer 1] to the resist composition, it is preferable for the resist composition for immersion exposure to have high hydrophobicity during immersion exposure and hydrophilicity during alkali development. It is clear that can be given.

[Resist pattern formation]
Next, an organic antireflection film composition “ARC29A” (trade name, manufactured by Brewer Science Co., Ltd.) was applied onto a 12-inch silicon wafer using a spinner, and baked on a hot plate at 205 ° C. for 60 seconds. By drying, an organic antireflection film having a film thickness of 89 nm was formed. Then, each of the resist compositions is applied onto the antireflection film using a spinner, prebaked (PAB) on a hot plate at 110 ° C. for 60 seconds, and dried to obtain a film thickness. A 100 nm resist film was formed.
Next, an ArF excimer laser (193 nm) is applied to the resist film through a mask pattern using an ArF immersion exposure apparatus NSR-S609B (manufactured by Nikon; NA (numerical aperture) = 1.07, σ0.97). ) Was selectively irradiated. Then, PEB processing is performed at 110 ° C. for 60 seconds, and further development processing is performed for 30 seconds with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution at 23 ° C., and then pure water is used for 30 seconds. Rinse with water and shake off to dry.
As a result, in each example, a line and space pattern having a line width of 55 nm and a pitch of 110 nm was formed on the resist film.

  From the above results, it was confirmed that the resist composition for immersion exposure according to the present invention is useful as a resist composition.

It is a figure explaining advancing angle ((theta) ₁ ), receding angle ((theta) ₂ ), and falling angle ((theta) ₃ ).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Droplet, 1a ... Lower end, 1b ... Upper end, 2 ... Plane, [theta] ₁ ... Advance angle, [theta] ₂ ... Receding angle, [theta] ₃ ... Falling angle

Claims (12)

A base component (A) whose solubility in an alkaline developer is changed by the action of an acid, an acid generator component (B) that generates an acid upon exposure, and a structural unit represented by the following general formula (c1-1) A resist composition for immersion exposure comprising (c1) and a fluorine-containing copolymer (C) having a structural unit (c2) represented by the following general formula (c2-1).

[Wherein, R ¹ is each independently a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; Q ¹ is each independently a single bond or a divalent linking group; A _B is a substituent; A is an optionally substituted benzene ring; A _N is an optionally substituted naphthalene ring; Q ² is each independently a group obtained by removing one hydrogen atom from a monovalent hydrophilic group; Yes; each R ² is independently a base dissociable group; each a is independently 1 or 2; in Formula (c1-1), at least one of A _N and a R ² is It has a fluorine atom; wherein (c2-1), at least one of _{a B} and a number of ^{R 2} is a fluorine atom. ]   The proportion of the structural unit (c1) in the fluorine-containing copolymer (C) is 1 to 40 mol% with respect to the total of all the structural units constituting the fluorine-containing copolymer (C). 2. The resist composition for immersion exposure according to 1. The resist composition for immersion exposure according to claim 1, wherein R ² is at least one selected from the groups represented by the following general formulas (II-1) to (II-3).

[Wherein, each R ⁴ is independently a hydrocarbon group optionally having a fluorine atom. ]   The resist composition for immersion exposure according to any one of claims 1 to 3, wherein the substrate component (A) is a substrate component whose solubility in an alkaline developer is increased by the action of an acid.   The base material component (A) contains a resin component (A1) whose solubility in an alkaline developer is increased by the action of an acid, and the resin component (A1) contains an acid dissociable, dissolution inhibiting group. The resist composition for immersion exposure according to claim 4, which has a structural unit (a1) derived from   The resist composition for immersion exposure according to claim 5, wherein the resin component (A1) further has a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.   The resist composition for immersion exposure according to claim 5 or 6, wherein the resin component (A1) further comprises a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group.   The resist composition for immersion exposure according to any one of claims 1 to 7, comprising a nitrogen-containing organic compound (D).   A step of forming a resist film on the support using the resist composition for immersion exposure according to any one of claims 1 to 8, a step of performing immersion exposure of the resist film, and an alkali of the resist film A resist pattern forming method including a step of developing and forming a resist pattern. A fluorine-containing copolymer having a structural unit (c1) represented by the following general formula (c1-1) and a structural unit (c2) represented by the following general formula (c2-1).

[Wherein, R ¹ is each independently a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; Q ¹ is each independently a single bond or a divalent linking group; A _B is a substituent; A is an optionally substituted benzene ring; A _N is an optionally substituted naphthalene ring; Q ² is each independently a group obtained by removing one hydrogen atom from a monovalent hydrophilic group; Yes; each R ² is independently a base dissociable group; each a is independently 1 or 2; in Formula (c1-1), at least one of A _N and a R ² is It has a fluorine atom; wherein (c2-1), at least one of _{a B} and a number of ^{R 2} is a fluorine atom. ]   The proportion of the structural unit (c1) in the fluorine-containing copolymer (C) is 1 to 40 mol% with respect to the total of all the structural units constituting the fluorine-containing copolymer (C). 10. The fluorine-containing copolymer according to 10. The fluorine-containing copolymer according to claim 10 or 11, wherein R ² is at least one selected from groups represented by the following general formulas (II-1) to (II-3).

[Wherein, each R ⁴ is independently a hydrocarbon group optionally having a fluorine atom. ]

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