JP2010210796A - Positive resist composition, resist pattern forming method, high molecular compound, and compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition capable of forming a resist pattern of a good shape with reduced LWR by superior sensitivity, a high molecular compound that can be used as a base material of the positive resist composition, a compound that can be used for synthesizing a structural unit of the high molecular compound, and a resist pattern forming method. <P>SOLUTION: The positive resist composition contains a base material component (A) of which solubility to alkali developing solution increases by the action of acid, and an acid generator component (B) that generates acid by exposure. The base material component (A) contains a high molecular compound (A1) having a structural unit (a0) including an acid dissociable dissolution inhibiting group, and the acid dissociable dissolution inhibiting group in the structural unit (a0) includes a group expressed by a formula (a0-0-1). In the formula (a0-0-1), R<SP>1</SP>' and R<SP>2</SP>' independently represent a hydrogen atom or a 1-5C alkyl group respectively, Y<SP>1</SP>represents a single bond or a divalent linking group, and R<SP>3</SP>represents a cyclic group including -SO<SB>2</SB>- in its cyclic skeleton. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a novel polymer compound that can be used as a base component of a positive resist composition, a positive resist composition containing the polymer compound, a compound that can be used to synthesize constituent units of the polymer compound, and The present invention relates to a resist pattern forming method using the positive resist composition.

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 light 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.
A resist material in which the exposed portion changes to a property that dissolves in the developer is referred to as a positive type, and a resist material that changes to a property in which the exposed portion does not dissolve in the developer is referred to as a negative type.
In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, pattern miniaturization has been rapidly progressing due to advances in lithography technology.
As a technique for miniaturization, the wavelength of an exposure light source is generally shortened. Specifically, conventionally, ultraviolet rays typified by g-line and i-line have been used, but now mass production of semiconductor elements using a KrF excimer laser or an ArF excimer laser has started. In addition, studies have been made on F ₂ excimer lasers, electron beams, EUV (extreme ultraviolet rays), X-rays, and the like having shorter wavelengths than these excimer lasers.

Resist materials are required to have lithography characteristics such as sensitivity to these exposure light sources and resolution capable of reproducing a pattern with fine dimensions.
As a resist material that satisfies such requirements, a chemically amplified resist composition containing a base material component 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. ing.
For example, as a positive chemically amplified resist composition, a composition containing a resin component (base resin) whose solubility in an alkaline developer is increased by the action of an acid and an acid generator component is generally used. Yes. When such a resist film formed using the resist composition is selectively exposed at the time of resist pattern formation, an acid is generated from the acid generator in the exposed portion, and the alkali developer of the resin component is generated by the action of the acid. As a result, the exposed area becomes soluble in an alkaline developer.
Currently, as a resist base resin used in ArF excimer laser lithography and the like, a resin (acrylic resin) having a structural unit derived from (meth) acrylic acid ester in its main chain because of its excellent transparency near 193 nm ) And the like are generally used (see, for example, Patent Document 1). 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.
At present, as a base resin for a chemically amplified resist, a resin containing a plurality of structural units is used in order to improve lithography properties and the like. For example, in the case of the positive type, it usually contains a structural unit having an acid dissociable, dissolution inhibiting group that is dissociated by the action of an acid generated from an acid generator, and further has a structural unit having a polar group such as a hydroxyl group, a lactone structure. The thing containing the structural unit which has is used. Among these, the structural unit having a lactone structure is generally considered to contribute to the improvement of lithography properties by improving the adhesion of the resist film to the substrate and the affinity with an alkali developer.

JP 2003-241385 A

In the future, there are demands for new materials that can be used for lithography applications, as further progress in lithography technology and expansion of application fields are expected. For example, as the pattern becomes finer, the resist material is required to improve various lithography characteristics. For example, when the rectangular shape of the cross-sectional shape of the resist pattern is low or the LWR (line width roughness) is large, the formation of fine semiconductor elements may be adversely affected. The LWR is a phenomenon in which when a resist pattern is formed using a resist composition, the pattern surface is roughened (roughness), and the line width of the line pattern becomes nonuniform.
Therefore, the improvement of the resist pattern shape and LWR becomes more important as the pattern becomes finer.
In addition, for example, when forming a fine pattern in lithography using an electron beam or EUV, it is very important to form a resist pattern having a good shape with high sensitivity.
The present invention has been made in view of the above circumstances, and is a positive resist composition capable of forming a resist pattern having a good shape, a low LWR, and a good shape, and a substrate for the positive resist composition. It is an object of the present invention to provide a polymer compound that can be used, a compound that can be used for the synthesis of a constituent unit of the polymer compound, and a method for forming a resist pattern.

In order to achieve the above object, the present invention employs the following configuration.
That is, the first aspect of the present invention is a positive type containing a base component (A) whose solubility in an alkaline developer is increased by the action of an acid, and an acid generator component (B) that generates an acid upon exposure. A resist composition, wherein the substrate component (A) includes a polymer compound (A1) having a structural unit (a0) containing an acid dissociable, dissolution inhibiting group, and acid dissociation in the structural unit (a0) The positive dissolution composition is characterized in that the soluble dissolution inhibiting group contains a group represented by the following general formula (a0-0-1).

［式（ａ０−０−１）中、Ｒ^１’およびＲ^２’はそれぞれ独立して水素原子または炭素数１〜５のアルキル基を表し、Ｙ^１は単結合または二価の連結基であり、Ｒ^３はその環骨格中に−ＳＯ_２−を含む環式基である。］

[In formula (a0-0-1), R ¹ ′ and R ² ′ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Y ¹ is a single bond or a divalent linking group. , R ³ is a cyclic group containing —SO ₂ — in the ring skeleton. ]

  According to a second aspect of the present invention, there is provided a step of forming a resist film on a support using the positive resist composition of the first aspect, a step of exposing the resist film, and an alkali development of the resist film. And a resist pattern forming method including a step of forming a resist pattern.

  In the third aspect of the present invention, the structural unit (a5) represented by the following general formula (a5-1) and at least a part of the hydrogen atoms in the hydroxyl group of the structural unit (a5) are represented by the following general formula (a0- And a structural unit (a0-5) substituted with a group represented by 0-1 ′).

［式（ａ５−１）中、Ｒ^１は水素原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基であり、Ｒ^２はハロゲン原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基であり；ｐは１〜３の整数であり、ｑは０〜４の整数である。ただし、ｐ＋ｑは１以上５以下である。］

[In Formula (a5-1), R ¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, and R ² is a halogen atom, an alkyl having 1 to 5 carbon atoms. A group or a halogenated alkyl group having 1 to 5 carbon atoms; p is an integer of 1 to 3, and q is an integer of 0 to 4. However, p + q is 1 or more and 5 or less. ]

［式（ａ０−０−１’）中、Ｒ^１’およびＲ^２’はそれぞれ独立して水素原子または炭素数１〜５のアルキル基を表し、Ｙ^１は単結合または二価の連結基であり、ａは０〜２の整数であり、Ｒ^６はアルキル基、アルコキシ基、ハロゲン化アルキル基、水酸基、−ＣＯＯＲ”、−ＯＣ（＝Ｏ）Ｒ”、ヒドロキシアルキル基またはシアノ基であり、Ｒ”は水素原子またはアルキル基であり、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。］

[In formula (a0-0-1 ′), R ¹ ′ and R ² ′ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Y ¹ represents a single bond or a divalent linking group. A is an integer of 0 to 2, R ⁶ is an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyl group, —COOR ″, —OC (═O) R ″, a hydroxyalkyl group or a cyano group, R ″ is a hydrogen atom or an alkyl group, and A ′ is an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, an oxygen atom or a sulfur atom.]

  A fourth aspect of the present invention is a compound represented by the following general formula (a0-0-01).

［式（ａ０−０−０１）中、Ｙ^１は単結合または二価の連結基であり、ａは０〜２の整数であり、Ｒ^６はアルキル基、アルコキシ基、ハロゲン化アルキル基、水酸基、−ＣＯＯＲ”、−ＯＣ（＝Ｏ）Ｒ”、ヒドロキシアルキル基またはシアノ基であり、Ｒ”は水素原子またはアルキル基であり、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。］

[In Formula (a0-0-01), Y ¹ is a single bond or a divalent linking group, a is an integer of 0 to 2, and R ⁶ is an alkyl group, an alkoxy group, a halogenated alkyl group, or a hydroxyl group. , —COOR ″, —OC (═O) R ″, a hydroxyalkyl group or a cyano group, R ″ is a hydrogen atom or an alkyl group, and A ′ is a carbon number that may contain an oxygen atom or a sulfur atom. 1 to 5 alkylene groups, oxygen atoms, or sulfur atoms.]

In the present specification and claims, “aliphatic” is a relative concept with respect to aromatics, and is defined to mean groups, compounds, etc. that do not have aromaticity.
Unless otherwise specified, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups.
Unless otherwise specified, the “alkylene group” includes linear, branched and cyclic divalent saturated hydrocarbon groups. The same applies to the alkyl group in the alkoxy group.
The “halogenated alkyl group” is a group in which part or all of the hydrogen atoms of the alkyl group are substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
“Fluorinated alkyl group” or “fluorinated alkylene group” refers to a group in which part or all of the hydrogen atoms of an alkyl group or alkylene group are substituted with fluorine atoms.
“Structural unit” means a monomer unit (monomer unit) constituting a polymer compound (resin, polymer, copolymer).
The “structural unit derived from an acrylate ester” means a structural unit constituted by cleavage of an ethylenic double bond of an acrylate ester.
“Acrylic acid esters” include those in which a hydrogen atom is bonded to the carbon atom at the α-position, and those in which a substituent (atom or group other than a hydrogen atom) is bonded to the carbon atom in the α-position. Include concepts. Examples of the substituent bonded to the α-position carbon atom include an alkyl group having 1 to 5 carbon atoms, a halogenated alkyl group having 1 to 5 carbon atoms, and a hydroxyalkyl group. The α-position carbon atom of the acrylate ester is a carbon atom to which a carbonyl group is bonded unless otherwise specified.
“Exposure” is a concept including general irradiation of radiation.

  ADVANTAGE OF THE INVENTION According to this invention, the positive resist composition which can form the resist pattern of the favorable shape with small sensitivity and LWR, the high molecular compound which can be utilized as a base material of this positive resist composition, this high molecular compound The compound which can be used for the synthesis | combination of these structural units, and the resist pattern formation method can be provided.

≪Positive resist composition≫
The positive resist composition of the present invention comprises a resin component (A) (hereinafter referred to as (A) component) whose solubility in an alkaline developer is increased by the action of an acid, and an acid generator component that generates an acid upon exposure. (B) (hereinafter referred to as component (B)).
In the positive resist composition of the present invention, the component (A) is insoluble in an alkali developer before exposure, and when an acid generated from the component (B) by exposure acts, an acid dissociable, dissolution inhibiting group. Dissociates, whereby the solubility of the entire component (A) in the alkali developer increases, and the alkali-insoluble is changed to alkali-soluble. Therefore, when a resist film obtained by using a positive resist composition is selectively exposed in the formation of a resist pattern, the exposed portion turns alkali-soluble, while the unexposed portion remains alkali-insoluble. Therefore, a resist pattern can be formed by alkali development.

Here, the “base material component” is an organic compound having a film forming ability. As the substrate component, 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.
“Organic compounds having a molecular weight of 500 or more” used as the base component are roughly classified into non-polymers and polymers.
As the non-polymer, those having a molecular weight of 500 or more and less than 4000 are usually used. Hereinafter, a nonpolymer having a molecular weight of 500 or more and less than 4000 is referred to as a low molecular compound.
As the polymer, those having a molecular weight of 2000 or more are usually used. Hereinafter, a polymer having a molecular weight of 2000 or more is referred to as a polymer compound. In the case of a polymer compound, the “molecular weight” is a polystyrene-reduced mass average molecular weight determined by GPC (gel permeation chromatography). Hereinafter, the polymer compound may be simply referred to as “resin”.

<(A) component>
[Polymer Compound (A1)]
In the positive resist composition of the present invention, the component (A) contains a polymer compound (A1) (hereinafter referred to as the component (A1)). The component (A1) has a structural unit (a0) containing an acid dissociable, dissolution inhibiting group, and the acid dissociable dissolution inhibiting group in the structural unit (a0) has the general formula (a0-0-1). The group represented by these is included.
As said (A1) component, 1 type may be used independently and 2 or more types may be used together.

  In addition to the component (A1), the component (A) may be a low molecular compound component (A2) (hereinafter referred to as “component (A2)”) whose solubility in an alkaline developer is increased by the action of an acid. ) May be contained.

In the positive resist composition of the present invention, in particular, the component (A1) contains a structural unit (a5) represented by the general formula (a5-1) described later and a hydrogen atom in the hydroxyl group of the structural unit (a5). It is preferable that at least a part of has a structural unit (a0-5) substituted with a group represented by the general formula (a0-0-1).
In addition to the structural unit (a0), the component (A1) may have a structural unit other than the structural unit (a5).

<Structural unit (a0)>
The structural unit (a0) is a structural unit in which the acid dissociable, dissolution inhibiting group in the structural unit (a0) includes a group represented by the general formula (a0-0-1).
In the general formula (a0-0-1), R ¹ ′ and R ² ′ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Y ¹ is a single bond or a divalent linkage. R ³ is a cyclic group containing —SO ₂ — in its ring skeleton.

Examples of the alkyl group having 1 to 5 carbon atoms of R ¹ ′ and R ² ′ include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, and an isopentyl group. And a linear or branched alkyl group such as a neopentyl group, 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.

As the divalent linking group for Y ¹ , an alkylene group having 2 to 15 carbon atoms, —C (═O) —, —C (═O) —O—, —NH—C (═O) —, or A combination of these, or a combination of —O—, a carbonate bond (—O—C (═O) —O—), and a linking group such as the above-described alkylene group can be given. In addition, —NH— (H may be substituted with a substituent such as an alkyl group or an acyl group), —S—, —S (═O) ₂ —, —S (═O) ₂ —O—. And so on. Among these, the divalent linking group for Y ¹ is preferably an alkylene group having 2 to 15 carbon atoms.

  Examples of the alkylene group having 2 to 15 carbon atoms include linear, branched or cyclic alkylene groups, linear or branched alkylene groups having 1 to 5 carbon atoms, and 4 to 12 carbon atoms. Cyclic alkylene group is preferable, and a linear or branched alkylene group having 1 to 5 carbon atoms is more preferable.

Specific examples of the alkylene group for Y ¹ 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: 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 — and the like Alkyltrimethylene group; tetramethylene 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 — and the like alkyltetramethylene groups; pentamethylene group [—CH ₂ CH _{2 CH 2 CH 2 CH 2 -]} , hexamethylene group _{[-CH 2 CH 2 CH 2 CH} 2 CH 2 CH 2 -], heptamethylene group _{[-CH 2 CH 2 CH 2 CH} 2 CH 2 CH 2 CH 2 -] , Octamethylene group [—CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ —], nonamethylene group [—CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ —], And a decamethylene group [—CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ —] and the like.

The alkylene group for Y ¹ may be a cyclic alkylene group (hereinafter referred to as “Rc”), or a combination of Rc and a chain alkylene group.
When Y ¹ is Rc or a combination of Rc and a chain alkylene group, Y ¹ preferably has 3 to 15 carbon atoms, more preferably 5 to 12 carbon atoms, and 6 to 10 carbon atoms. It is particularly preferred. Rc may be a monocyclic group or a polycyclic group.
In the case where Y ¹ is a combination of Rc and a chain alkylene group, a group in which the Rc is interposed between the terminal of the chain alkylene group or the carbon atom is exemplified.
Specific examples of Y ¹ include —Rc—, —CH ₂ —Rc—CH ₂ —, —CH ₂ —Rc—CH ₂ CH ₂ —, —CH ₂ CH ₂ —Rc—CH ₂ —, —CH. _{2 CH 2 -Rc-CH 2 CH} 2 -, - CH 2 -Rc-CH 2 CH 2 CH 2 CH 2 - and the like. Of these, —CH ₂ —Rc—CH ₂ — is preferable.
Rc is preferably a monocyclic group having 5 to 6 carbon atoms.

The alkylene group for Y ¹ may have a substituent.
The term “having a substituent” for an alkylene group means that part or all of the hydrogen atoms in the alkylene group are substituted with atoms or groups other than hydrogen atoms.
Specific examples of the substituent for substituting part or all of the hydrogen atom include an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, an oxygen atom (═O), and a cyano group.
The alkoxy group is preferably an alkoxy group having 1 to 5 carbon atoms, preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, or a tert-butoxy group, and a methoxy group or an ethoxy group. Is most preferred.
As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned, A fluorine atom is preferable.
As the halogenated alkyl group, a part or all of hydrogen atoms of an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a tert-butyl group, etc. And a group substituted with a halogen atom.

In the general formula (a0-0-1), R ³ is a cyclic group containing —SO ₂ — in the ring skeleton.
The cyclic group in R ³ represents a cyclic group containing a ring containing —SO ₂ — in the ring skeleton, and the ring is counted as the first ring. When only the ring is present, a monocyclic group Further, when it has another ring structure, it is called a polycyclic group regardless of the structure. The cyclic group for R ³ may be a monocyclic group or a polycyclic group.
R ³ is particularly preferably a cyclic group containing —O—SO ₂ — in its ring skeleton.
The cyclic group for R ³ preferably has 3 to 30 carbon atoms, preferably 4 to 20 carbon atoms, more preferably 4 to 15 carbon atoms, and particularly preferably 4 to 12 carbon atoms. However, the carbon number is the number of carbon atoms constituting the ring skeleton, and does not include the carbon number in the substituent.
The cyclic group for R ³ may be an aliphatic cyclic group or an aromatic cyclic group. An aliphatic cyclic group is preferable.
The ring skeleton of the cyclic aliphatic hydrocarbon group for R ³ may be a polycyclic group or a monocyclic group. As the monocyclic group, a group in which one hydrogen atom is removed from a monocycloalkane having 3 to 6 carbon atoms is preferable, and examples of the monocycloalkane include cyclopentane and cyclohexane. As the polycyclic group, a group in which one hydrogen atom is removed from a polycycloalkane having 7 to 12 carbon atoms is preferable. Specific examples of the polycycloalkane include adamantane, norbornane, isobornane, tricyclodecane, tetra And cyclododecane.
As the aliphatic cyclic group for R ^3, a carbon atom constituting a ring skeleton of the cyclic aliphatic hydrocarbon group mentioned above is partially substituted with —SO ₂ — or —O—SO ₂ —. Is mentioned.
More specifically, for example, the monocyclic group includes a group obtained by removing one hydrogen atom from a monocycloalkane in which —CH ₂ — constituting the ring skeleton is substituted with —SO ₂ —, and the ring constituting a _-CH 2 -CH ₂ - is -O-SO ₂ - include groups which one hydrogen atom has been removed from mono cycloalkane substituted by an. The polycyclic group includes one hydrogen atom from a polycycloalkane (bicycloalkane, tricycloalkane, tetracycloalkane, etc.) in which —CH ₂ — constituting the ring skeleton is substituted with —SO ₂ —. And a group obtained by removing one hydrogen atom from a polycycloalkane in which —CH ₂ —CH ₂ — constituting the ring is substituted with —O—SO ₂ —.

The cyclic group for R ³ may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, an oxygen atom (═O), —COOR ″, —OC (═O) R ″, a hydroxyalkyl group, a cyano group, and the like. Is mentioned.
The alkyl group as the substituent is preferably an alkyl group having 1 to 6 carbon atoms. The alkyl group is preferably linear or branched. Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and a hexyl group. Among these, a methyl group or an ethyl group is preferable, and a methyl group is particularly preferable.
The alkoxy group as the substituent is preferably an alkoxy group having 1 to 6 carbon atoms. The alkoxy group is preferably linear or branched. Specifically, the group which the alkyl group quoted as the alkyl group as the said substituent couple | bonded with the oxygen atom (-O-) is mentioned.
Examples of the halogen atom as the substituent include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is preferable.
Examples of the halogenated alkyl group as the substituent include groups in which part or all of the hydrogen atoms of the alkyl group mentioned as the alkyl group as the substituent are substituted with the halogen atom. As the halogenated alkyl group, a fluorinated alkyl group is preferable, and a perfluoroalkyl group is particularly preferable.
R ″ in —COOR ″ and —OC (═O) R ″ is a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 15 carbon atoms.
When R ″ is a linear or branched alkyl group, it preferably has 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms, and particularly preferably a methyl group or an ethyl group. preferable.
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 a group in which one or more hydrogen atoms are removed from a polycycloalkane such as monocycloalkane, bicycloalkane, tricycloalkane, tetracycloalkane, which may or may not be substituted with a fluorinated alkyl group More specifically, one or more hydrogen atoms are removed from a monocycloalkane such as cyclopentane or cyclohexane, or a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Group and the like.
The hydroxyalkyl group as the substituent is preferably one having 1 to 6 carbon atoms. Specifically, at least one of the hydrogen atoms of the alkyl group mentioned as the alkyl group as the substituent is substituted with a hydroxyl group. Group.
More specific examples of R ³ include groups represented by the following general formulas (3-1) to (3-4).

［式中、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り、ａは０〜２の整数であり、Ｒ^６はアルキル基、アルコキシ基、ハロゲン化アルキル基、水酸基、−ＣＯＯＲ”、−ＯＣ（＝Ｏ）Ｒ”、ヒドロキシアルキル基またはシアノ基であり、Ｒ”は水素原子またはアルキル基である。］

[Wherein, A ′ is an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, an oxygen atom or a sulfur atom, a is an integer of 0 to 2, and R ⁶ is an alkyl group. An alkoxy group, a halogenated alkyl group, a hydroxyl group, —COOR ″, —OC (═O) R ″, a hydroxyalkyl group or a cyano group, and R ″ is a hydrogen atom or an alkyl group.]

In the general formulas (3-1) to (3-4), A ′ represents an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom (—O—) or a sulfur atom (—S—), An oxygen atom or a sulfur atom.
The alkylene group having 1 to 5 carbon atoms in A ′ is preferably a linear or branched alkylene group, and examples thereof include a methylene group, an ethylene group, an n-propylene group, and an isopropylene group.
When the alkylene group contains an oxygen atom or a sulfur atom, specific examples thereof include a group in which —O— or —S— is interposed between the terminal or carbon atoms of the alkylene group, for example, —O—CH _{2. -, - CH 2 -O-CH} 2 -, - S-CH 2 -, - CH 2 -S-CH 2 - , and the like.
A ′ is preferably an alkylene group having 1 to 5 carbon atoms or —O—, more preferably an alkylene group having 1 to 5 carbon atoms, and most preferably a methylene group.
a may be any of 0 to 2, and 0 is most preferable.
When a is 2, the plurality of R ⁶ may be the same or different.
The alkyl group in R ^6, an alkoxy group, a halogenated alkyl group, -COOR ", - OC (= O) R", The hydroxyalkyl groups, respectively, may have the cyclic group in ^{R 3} substituent Examples thereof include the same alkyl groups, alkoxy groups, halogenated alkyl groups, —COOR ″, —OC (═O) R ″, and hydroxyalkyl groups mentioned as groups.
Below, the specific cyclic group represented by the said general formula (3-1)-(3-4) is illustrated. In the formula, “Ac” represents an acetyl group.

Among these, R ³ is preferably a group represented by the general formula (3-1), and the chemical formulas (3-1-1), (3-1-18), (3-3-1) are preferable. It is more preferable to use at least one selected from the group consisting of the group represented by any one of (3-4-1) and the group represented by the chemical formula (3-1-1) is most preferable.

  In the structural unit (a0), the group represented by the general formula (a0-1-1) is preferably a group represented by the following general formula (a0-1-1 ').

［式（ａ０−０−１’）中、Ｒ^１’およびＲ^２’はそれぞれ独立して水素原子または炭素数１〜５のアルキル基を表し、Ｙ^１は単結合または二価の連結基であり、ａは０〜２の整数であり、Ｒ^６はアルキル基、アルコキシ基、ハロゲン化アルキル基、水酸基、−ＣＯＯＲ”、−ＯＣ（＝Ｏ）Ｒ”、ヒドロキシアルキル基またはシアノ基であり、Ｒ”は水素原子またはアルキル基であり、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。］

[In formula (a0-0-1 ′), R ¹ ′ and R ² ′ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Y ¹ represents a single bond or a divalent linking group. A is an integer of 0 to 2, R ⁶ is an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyl group, —COOR ″, —OC (═O) R ″, a hydroxyalkyl group or a cyano group, R ″ is a hydrogen atom or an alkyl group, and A ′ is an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, an oxygen atom or a sulfur atom.]

In the formula (a0-0-1 ′), R ¹ ′, R ² ′, Y ¹ , a, R ⁶ , and A ′ are R ¹ ′, R ² ′ in the general formula (a0-0-1), Y ^{1 is} the same as a, R ⁶ , and A ′ of General Formula (3-1).

  Preferred specific examples of the group represented by the formula (a0-0-1 ') are shown below.

In the structural unit (a0), the group represented by the general formula (a0-0-1) is a hydrogen atom in a phenolic hydroxyl group (—OH), a carboxy group (—COOH), or a thiol group (—SH). A substituent is preferred. Moreover, it is preferable that the group represented by the general formula (a0-0-1) is a hydrogen atom substituent in a sulfo group (—SO ₃ H).
When the group represented by the general formula (a0-0-1) is a substituent of a hydrogen atom in these groups, the group represented by the general formula (a0-0-1) acts as an acid. It becomes an acid dissociable group that dissociates by the above, and can function as an acid dissociable, dissolution inhibiting group for the structural unit (a0).

  In the present invention, the structural unit (a0) is particularly preferably a structural unit represented by the following general formula (a0-1).

［式（ａ０−１）中、Ｒは水素原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基であり；Ｙ^０１は、２価の芳香族基、；Ｙ^０２は、−Ｏ−、−Ｃ（＝Ｏ）Ｏ−、または−Ｓ−であり；Ｒ^１’およびＲ^２’はそれぞれ独立して水素原子または炭素数１〜５のアルキル基を表し、Ｙ^１は単結合または二価の連結基であり、ａは０〜２の整数であり、Ｒ^６はアルキル基、アルコキシ基、ハロゲン化アルキル基、水酸基、−ＣＯＯＲ”、−ＯＣ（＝Ｏ）Ｒ”、ヒドロキシアルキル基またはシアノ基であり、Ｒ”は水素原子またはアルキル基であり、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。］

[In the formula (a0-1), R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms; Y ⁰¹ is a divalent aromatic group; Y ⁰² Is —O—, —C (═O) O—, or —S—; R ¹ ′ and R ² ′ each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Y ¹ Is a single bond or a divalent linking group, a is an integer of 0 to 2, R ⁶ is an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyl group, —COOR ″, —OC (═O) R ″. , A hydroxyalkyl group or a cyano group, R ″ is a hydrogen atom or an alkyl group, and A ′ is an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, an oxygen atom or a sulfur atom. Is.]

In formula (a0-1), R ¹ ′, R ² ′, Y ¹ , R ⁶ , a, and A ′ are the same as described above.
A ′ is an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, an oxygen atom or a sulfur atom, and a methylene group, an oxygen atom (—O—) or a sulfur atom (—S—). It is preferable that

In formula (a0-1), R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms.
The alkyl group having 1 to 5 carbon atoms in R is preferably a linear or branched alkyl group having 1 to 5 carbon atoms. Specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, n -Butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like can be mentioned.
The halogenated alkyl group having 1 to 5 carbon atoms in R is a group in which part or all of the hydrogen atoms of the alkyl group having 1 to 5 carbon atoms are substituted with a halogen atom. 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 is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms, and is most preferably a hydrogen atom or a methyl group in terms of industrial availability.

In formula (a0-1), Y ⁰¹ represents a divalent aromatic group.
Specific examples of Y ⁰¹ include a group obtained by removing two hydrogen atoms from an aromatic hydrocarbon ring which may have a substituent.
The ring skeleton of the aromatic cyclic group for Y ⁰¹ preferably has 6 to 15 carbon atoms, and examples thereof include a benzene ring, a naphthalene ring, a phenanthrene ring, and an anthracene ring. Among these, a benzene ring or a naphthalene ring is particularly preferable.
In Y ⁰¹ , examples of the substituent that the aromatic cyclic group may have include a halogen atom, an alkyl group, an alkoxy group, a halogenated alkyl group having 1 to 5 carbon atoms, and an oxygen atom (═O). Can be mentioned. Examples of the halogen atom include a fluorine atom, a chlorine atom, an iodine atom, and a bromine atom. The aromatic cyclic substituent which may be have a Y ^01, is preferably a fluorine atom.
The aromatic cyclic group Y ^01, may be one having no substituent, may be those having a substituent is preferably one having no substituent.
In Y ⁰¹ , when the aromatic cyclic group has a substituent, the number of substituents may be one, two or more, and one or two. Is preferable, and one is more preferable.

In formula (a0-1), Y ⁰² represents —O—, —C (═O) O—, or —S—.
Among these, as Y ⁰² , —O— and —C (═O) O— are preferable, and —O— is more preferable.

As the structural unit (a0), one type may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a0) in the component (A1) is such that the sensitivity when forming a resist pattern using the positive resist composition containing the component (A1), the shape of the resist pattern formed, and the LWR Since it is excellent in (line width roughness), it is preferable that it is 5-60 mol% with respect to all the structural units which comprise (A1) component, 5-50 mol% is more preferable, and 10-40 mol% is further preferable.

The main chain in the structural unit (a0) is not particularly limited, and examples thereof include a structural unit derived from hydroxystyrene.
Here, in the present specification and claims, the “structural unit derived from hydroxystyrene” means a structural unit formed by cleavage of an ethylenic double bond of hydroxystyrene.

“Hydroxystyrene” means hydroxystyrene and a hydrogen atom in the α-position of hydroxystyrene substituted with another substituent such as an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms. As well as their derivatives. Note that the α-position (α-position carbon atom) of a structural unit derived from hydroxystyrene means a carbon atom to which a benzene ring is bonded, unless otherwise specified.
In hydroxystyrene, as an alkyl group having 1 to 5 carbon atoms as a substituent at the α-position, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, Examples thereof include linear or branched alkyl groups such as a pentyl group, isopentyl group, and neopentyl group.
In hydroxystyrene, as the halogenated alkyl group having 1 to 5 carbon atoms as the substituent at the α-position, specifically, the hydrogen atom of the above “alkyl group having 1 to 5 carbon atoms as the substituent at the α-position” Examples include a group in which a part or all of them are substituted with a halogen atom. 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 hydroxystyrene is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. It is more preferably an alkyl group having 1 to 5 carbon atoms or a fluorinated alkyl group having 1 to 5 carbon atoms, and most preferably a hydrogen atom or a methyl group in terms of industrial availability.

  Specifically as a suitable thing in a structural unit (a0), as a structural unit induced | guided | derived from hydroxystyrene, for example in the hydroxyl group of the structural unit (a5) represented by the following general formula (a5-1) And a structural unit (a0-5) in which at least a part of the hydrogen atoms is substituted with a group represented by the general formula (a0-0-1).

<Structural unit (a0-5)>
In the structural unit (a0-5), at least part of the hydrogen atoms in the hydroxyl group of the structural unit (a5) represented by the general formula (a5-1) described later is represented by the general formula (a0-0-1). That is, a structural unit represented by the following general formula (a0-5-1).

［式（ａ０−５−１）中、Ｒ^１’、Ｒ^２’、Ｙ^１、およびＲ^３は式（ａ０−０−１）におけるＲ^１’、Ｒ^２’、Ｙ^１、およびＲ^３と同じであり；Ｒ^１は水素原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基であり、Ｒ^２はハロゲン原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基であり；ｐは１〜３の整数であり、ｑは０〜４の整数である。ただし、ｐ＋ｑは１以上５以下である。］

Wherein ^{(a0-5-1), R 1 ',} R 2', Y 1, and ^{R 3} is ^{R 1} in formula ^{(a0-0-1) ', R 2'} , and ^{Y 1,} and ^{R 3} R ¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, and R ² is a halogen atom, an alkyl group having 1 to 5 carbon atoms or 1 carbon atom. A halogenated alkyl group of ˜5; p is an integer of 1 to 3, and q is an integer of 0 to 4. However, p + q is 1 or more and 5 or less. ]

In the formula (a0-5-1), R ¹ represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms.
Examples of the alkyl group for R ¹ include the same alkyl groups having 1 to 5 carbon atoms that may be bonded to the α-position of the hydroxystyrene.
Examples of the halogenated alkyl group for R ¹ include groups in which some or all of the hydrogen atoms in the aforementioned “alkyl group having 1 to 5 carbon atoms which may be bonded to the α-position of hydroxystyrene” are substituted with halogen atoms. It is done. 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 said formula (a0-5-1), R < ² > is a halogen atom, a C1-C5 alkyl group, or a C1-C5 halogenated alkyl group.
Examples of the halogen atom for R ² include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable.
Examples of the alkyl group having 1 to 5 carbon atoms of R ² include the same alkyl groups having 1 to 5 carbon atoms that may be bonded to the α-position of the hydroxystyrene.
Halogenated alkyl group having 1 to 5 carbon atoms for R ^2, the part or all of the hydrogen atoms of the alkyl group having 1 to 5 carbon atoms for R ² can be mentioned groups substituted with a halogen atom, a carbon number 1 A fluorinated alkyl group of ˜5 is preferred.

In the formula (a0-5-1), p is an integer of 1 to 3, and preferably 1.
The bonding position of the hydroxyl group may be any of the o-position, m-position and p-position of the phenyl group. When p is 1, the p-position is preferred because it is readily available and inexpensive. When p is 2 or 3, arbitrary substitution positions can be combined.

In the formula (a0-5-1), q is an integer of 0 to 4, preferably an integer of 0 to 2, preferably 0 or 1, and particularly industrially 0. preferable.
When q is 1, the substitution position of R ² may be any of the o-position, m-position, and p-position. When q is 2, arbitrary substitution positions can be combined. The plurality of R ² may be the same or different.
However, p + q is 1 or more and 5 or less.

  As the structural unit (a0-5) represented by the formula (a0-5-1), those represented by the following general formula (a0-5-1 ') are particularly preferable.

［式（ａ０−５−１’）中、Ｒ^１’、Ｒ^２’、Ｙ^１、ａ、Ｒ^６、およびＡ’は、式（ａ０−０−１’）におけるＲ^１’、Ｒ^２’、Ｙ^１、ａ、Ｒ^６、およびＡ’と同じであり；Ｒ^１は水素原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基であり、Ｒ^２はハロゲン原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基であり；ｐは１〜３の整数であり、ｑは０〜４の整数である。ただし、ｐ＋ｑは１以上５以下である。］

[In formula (a0-5-1 ′), R ¹ ′, R ² ′, Y ¹ , a, R ⁶ , and A ′ represent R ¹ ′ and R ² ′ in formula (a0-0-1 ′). , Y ¹ , a, R ⁶ and A ′; R ¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, and R ² is a halogen atom. , An alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms; p is an integer of 1 to 3, and q is an integer of 0 to 4. However, p + q is 1 or more and 5 or less. ]

In the formula ^{(a0-5-1 '), R 1,} R 2, p, and q are the same as ^{R 1, R} 2, p, and q in the general formula (a0-5-1).
In the formula (a0-5-1 ′), R ¹ ′, R ² ′, Y ¹ , a, R ⁶ , and A ′ represent R ¹ ′ and R ² in the formula (a0-0-1 ′). Same as ', Y ¹ , a, R ⁶ , and A'.

<Structural unit (a5)>
The structural unit (a5) is a structural unit represented by the following general formula (a5-1).
When the component (A1) has the structural unit (a5), in addition to the effects of the present invention, dry etching resistance is improved. Furthermore, the structural unit (a5) also has the advantage that the raw material hydroxystyrene is readily available and is inexpensive.

［式（ａ５−１）中、Ｒ^１は水素原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基であり、Ｒ^２はハロゲン原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基であり；ｐは１〜３の整数であり、ｑは０〜４の整数である。ただし、ｐ＋ｑは１以上５以下である。］

[In Formula (a5-1), R ¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, and R ² is a halogen atom, an alkyl having 1 to 5 carbon atoms. A group or a halogenated alkyl group having 1 to 5 carbon atoms; p is an integer of 1 to 3, and q is an integer of 0 to 4. However, p + q is 1 or more and 5 or less. ]

In the formula (a5-1), R ¹ , R ² , p and q are the same as R ¹ , R ² , p and q in the formula (a0-5-1), respectively.

In the component (A1), as the structural unit (a5), one type of structural unit may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a5) in the component (A1) is preferably 45 to 90 mol%, more preferably 50 to 85 mol%, based on the total of all structural units constituting the component (A1). Preferably, 55 to 80 mol% is more preferable. By setting it to be equal to or higher than the lower limit of the above range, moderate alkali solubility can be obtained. Moreover, the effect by containing a structural unit (a5) is fully acquired. By setting it to be equal to or less than the upper limit value of the range, it is possible to balance with other structural units.

<Other structural units>
The component (A1) may contain other structural units other than the structural unit (a0) and the structural unit (a5) as long as the effects of the present invention are not impaired.
The other structural units are not particularly limited as long as they are other structural units that are not classified into the structural unit (a0) and the structural unit (a5) described above, and for resists such as for ArF excimer laser and KrF excimer laser. Many things conventionally known as what is used for resin can be used.
Examples of other structural units include a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group (excluding the structural unit (a0-1)), and a lactone-containing cyclic group. A structural unit derived from an acrylate ester containing (a2), a structural unit derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group (a3), an acid non-dissociable aliphatic polycyclic group A constitutional unit (a4) derived from an acrylate ester, a constitutional unit (a6) derived from styrene, and a constitution in which at least a part of hydrogen atoms in the hydroxyl group of the constitutional unit derived from hydroxystyrene is protected by a substituent A unit (a7) (excluding the structural unit (a0-5)), and the like.

<Structural unit (a1)>
The structural unit (a1) is a structural unit derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group, which does not correspond to the structural unit (a0-1).
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. It increases the solubility of the entire component in an alkaline developer, and those proposed so far 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.

Here, the term “aliphatic branched” in the claims and the specification 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), and 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 an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxygen atom (= O), and the like. Is mentioned.
The basic ring structure excluding the substituent of “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), and 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, tricyclos, which may or may not be substituted with an alkyl group having 1 to 5 carbon atoms, a fluorine atom or a fluorinated alkyl group. Examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as an alkane or tetracycloalkane. More specifically, 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- A 2-adamantyl group, a 2-ethyl-2-adamantyl group, and the like can be given. 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、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基を示し；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。］

In the formula, R represents a hydrogen atom, a halogenated alkyl group of 1 to 5 alkyl group or a C1-5 carbon; R ^15, R ¹⁶ is an alkyl group (straight, any branched Well, preferably 1 to 5 carbon atoms). ]

  In the general formulas (a1 ″ -1) to (a1 ″ -6), the alkyl group having 1 to 5 carbon atoms or the halogenated alkyl group having 1 to 5 carbon atoms of R is bonded to the α-position of the acrylate ester. And the same as the alkyl group having 1 to 5 carbon atoms or the halogenated alkyl group having 1 to 5 carbon atoms.

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, the 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’はそれぞれ上記と同じである。ｎは０〜３の整数を表し、Ｙは炭素数１〜５のアルキル基または脂肪族環式基を表す。］

[Wherein R ¹ ′ and R ² ′ are the same as above. n represents an integer of 0 to 3, and Y represents an alkyl group having 1 to 5 carbon atoms 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 alkyl group having 1 to 5 carbon atoms of R ¹ ′ and R ² ′ include those similar to the alkyl group having 1 to 5 carbon atoms of R, preferably a methyl group or an ethyl group, and most preferably a methyl group. 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 and Y are the same as described above. ]

In the above formula, examples of the alkyl group having 1 to 5 carbon atoms of Y include the same as the alkyl group having 1 to 5 carbon atoms of R.
The aliphatic cyclic group for Y can be appropriately selected from monocyclic or polycyclic aliphatic cyclic groups conventionally proposed in a number of ArF resists and the like. 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また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, tetracycloalkane, which may or may not be substituted with a fluorine atom or a fluorinated alkyl group. And the like, in which a hydrogen atom is removed. 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. Of these, a group in which one or more hydrogen atoms have been removed 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 R ¹⁷ The terminal may be bonded.
In this case, the R ^17, R ^19, the oxygen atom to which R ¹⁹ is bonded, the cyclic group is formed by the carbon atom having 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、炭素数１〜５のアルキル基または炭素数１〜５のハロゲンアルキル基を示し；Ｘ^１は酸解離性溶解抑制基を示す。］

[Wherein, R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogen alkyl group having 1 to 5 carbon atoms; X ¹ represents an acid dissociable, dissolution inhibiting group. ]

［式中、Ｒは水素原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲンアルキル基を示し；Ｘ^２は酸解離性溶解抑制基を示し；Ｙ^２は２価の連結基を示す。］

[Wherein, R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogen alkyl group having 1 to 5 carbon atoms; X ² represents an acid dissociable, dissolution inhibiting group; Y ² represents a divalent linking group. Indicates. ]

In the general formula (a1-0-1), the alkyl group having 1 to 5 carbon atoms or the halogenated alkyl group having 1 to 5 carbon atoms of R may be bonded to the α-position of the acrylate ester. It is the same as the alkyl group having ˜5 or the halogenated alkyl group having 1 to 5 carbon atoms.
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).

Examples of the divalent linking group for Y ² include an alkylene group, a divalent aliphatic cyclic group, and a divalent linking group containing a hetero atom.
As the aliphatic cyclic group, those similar to the explanation of the “aliphatic cyclic group” can be used except that a group in which two or more hydrogen atoms are removed is used.
When Y ² is an alkylene group, it is preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms, and 1 to 3 carbon atoms. Most preferably it is.
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. .
When Y ² is a divalent linking group containing a hetero atom, examples of the divalent linking group containing a hetero atom include —O—, —C (═O) —O—, —C (═O) —, —O—C (═O) —O—, —C (═O) —NH—, —NH— (H may be substituted with a substituent such as an alkyl group or an acyl group), —S—. , —S (═O) ₂ —, —S (═O) ₂ —O—, a group represented by the formula —A—O—B—, a formula — [A—C (═O) —O] _m —. Examples thereof include a group represented by B-. Here, A and B are each independently a divalent hydrocarbon group which may have a substituent, and m is an integer of 0 to 3.

When Y ² is —NH—, the substituent (alkyl group, acyl group, etc.) preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and more preferably 1 to 5 carbon atoms. It is particularly preferred that
When Y ² is the formula -A-O-B- or the formula-[A-C (= O) -O] _m -B-, A and B each independently have a substituent. It is also a good divalent hydrocarbon group.
The hydrocarbon group having “substituent” means that part or all of the hydrogen atoms in the hydrocarbon group are substituted with groups or atoms other than hydrogen atoms.

  The hydrocarbon group in A may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. An aliphatic hydrocarbon group means a hydrocarbon group having no aromaticity.

The aliphatic hydrocarbon group for A may be saturated or unsaturated, and is usually preferably saturated.
Specific examples of the aliphatic hydrocarbon group for A include a linear or branched aliphatic hydrocarbon group, and an aliphatic hydrocarbon group containing a ring in the structure.

The linear or branched aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, still more preferably 1 to 5, and most preferably 1 or 2.
As the linear aliphatic hydrocarbon group, a linear alkylene group is preferable, and specifically, a methylene group, an ethylene group [— (CH ₂ ) ₂ —], a trimethylene group [— (CH ₂ ) ₃ -], tetramethylene group _{[- (CH 2) 4 -} ], a pentamethylene group _{[- (CH 2) 5 -} ] , and the like.
As the branched aliphatic hydrocarbon group, a branched alkylene group is preferred, and specifically, —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 - Alkylethylene groups such as CH (CH ₃ ) CH ₂ —, —CH (CH ₃ ) CH (CH ₃ ) —, —C (CH ₃ ) ₂ CH ₂ —, —CH (CH ₂ CH ₃ ) CH ₂ —; Alkyl trimethylene groups such as —CH (CH ₃ ) CH ₂ CH ₂ —, —CH ₂ CH (CH ₃ ) CH ₂ —; —CH (CH ₃ ) CH ₂ CH ₂ CH ₂ —, —CH ₂ CH (CH _{3) CH} 2 CH ₂ - alkyl, such as alkyl tetramethylene group such as Such as an alkylene group, and the like. The alkyl group in the alkyl alkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.
The chain-like aliphatic hydrocarbon group may or may not have a substituent. Examples of the substituent include a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, and an oxygen atom (= O).

Examples of the aliphatic hydrocarbon group containing a ring include a cyclic aliphatic hydrocarbon group (a group obtained by removing two hydrogen atoms from an aliphatic hydrocarbon ring), and the cyclic aliphatic hydrocarbon group described above as a chain-like aliphatic group. Examples include a group bonded to the terminal of an aromatic hydrocarbon group or interposed in the middle of a chain aliphatic hydrocarbon group.
The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably 3 to 12 carbon atoms.
The cyclic aliphatic hydrocarbon group may be a polycyclic group or a monocyclic group. As the monocyclic group, a group in which two hydrogen atoms have been removed from a monocycloalkane having 3 to 6 carbon atoms is preferable, and examples of the monocycloalkane include cyclopentane and cyclohexane.
As the polycyclic group, a group in which two hydrogen atoms are removed from a polycycloalkane having 7 to 12 carbon atoms is preferable. Specific examples of the polycycloalkane include adamantane, norbornane, isobornane, tricyclodecane, tetra And cyclododecane.
The cyclic aliphatic hydrocarbon group may or may not have a substituent. Examples of the substituent include an alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, and an oxygen atom (= O).

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

Examples of the hydrocarbon group for B include the same divalent hydrocarbon groups as those described above for A.
B is preferably a linear or branched aliphatic hydrocarbon group, particularly preferably a methylene group or an alkylmethylene group.
The alkyl group in the alkylmethylene group is preferably a linear alkyl group having 1 to 5 carbon atoms, more preferably a linear alkyl group having 1 to 3 carbon atoms, and most preferably a methyl group.
In the group represented by the formula — [A—C (═O) —O] _m —B—, m is an integer of 0 to 3, preferably an integer of 0 to 2, and 0 or 1 Is more preferable and 1 is most preferable.
Y ² is preferably the alkylene group, divalent aliphatic cyclic group or divalent linking group containing a hetero atom. Among these, a divalent linking group containing a hetero atom is preferable, and a linear group having an oxygen atom as a hetero atom, for example, a group containing an ester bond is particularly preferable.
Among them, a group represented by the above-described —A—O—B— or —A—C (═O) —O—B— is preferable, and in particular, — (CH ₂ ) _x —C (═O) —O— ( CH _{2) y} - group represented by are preferred.
x is an integer of 1 to 5, preferably 1 or 2, and most preferably 1.
y is an integer of 1 to 5, preferably 1 or 2, and most preferably 1.

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

［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２価の連結基を表し；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のアルキル基を表す。］

[Wherein, X ′ represents a tertiary alkyl ester-type acid dissociable, dissolution inhibiting group, Y represents an alkyl group having 1 to 5 carbon atoms, or an aliphatic cyclic group; n represents an integer of 0 to 3; Y ² represents a divalent linking group; R is the same as defined above; R ¹ ′ and R ² ′ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. ]

In the formula, X 'include 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.
Y ² include the same as ^{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.
In the following formula, R ^α represents a hydrogen atom, a methyl group or a trifluoromethyl group.

As the structural unit (a1), one type may be used alone, or two or more types may be used in combination.
Among these, the structural unit represented by general formula (a1-1) or (a1-3) is preferable, and specifically, (a1-1-1) to (a1-1-4) and formula (a1-1) -16) to (a1-1-17), (a1-1-20) to (a1-1-23) and (a1-3-25) to (a1-3-28). More preferably, at least one kind is used.
Furthermore, as the structural unit (a1), those represented by the following general formula (a1-1-01) including particularly the structural units of the formula (a1-1-1) to the formula (a1-1-3), In the following general formula (a1-1-02) including the structural units of formulas (a1-1-16) to (a1-1-17) and formulas (a1-1-20) to (a1-1-23) Those represented are also preferred.

（式中、Ｒは水素原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基を示し、Ｒ^１１は炭素数１〜５のアルキル基を示す。Ｒ^１２は炭素数１〜５のアルキル基を示し、ｈは１〜６の整数を表す。）

(In the formula, R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, R ¹¹ represents an alkyl group having 1 to 5 carbon atoms, and R ¹² represents the number of carbon atoms. 1 to 5 alkyl groups are shown, and h represents an integer of 1 to 6.)

In general formula (a1-1-01), R is the same as defined above.
Alkyl group of 1 to 5 carbon atoms for R ¹¹ is the same as the alkyl group having 1 to 5 carbon atoms for R, a methyl group or an ethyl group is preferred.

In general formula (a1-1-02), R is the same as defined above.
The alkyl group having 1 to 5 carbon atoms of R ¹² is the same as the alkyl group having 1 to 5 carbon atoms in 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.

  In the component (A1), the proportion of the structural unit (a1) is preferably 10 to 80 mol%, more preferably 20 to 70 mol%, with respect to the total of all structural units constituting the component (A1). More preferred is mol%. By setting it to the lower limit value or more of the range, a pattern can be easily obtained when the resist composition is used, and by setting the upper limit value or less of the range, 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.
The “lactone-containing cyclic group” as used herein refers to a cyclic group containing one ring (lactone ring) containing a —O—C (O) — structure. The lactone ring is counted as the first ring. When only the lactone ring is present, it is called a monocyclic group. When it has another ring structure, it is called a polycyclic group regardless of the structure.
When the component (A1) is used for forming a resist film, the lactone cyclic group of the structural unit (a2) increases the adhesion of the resist film to the substrate or has an affinity for a developer containing water. It is effective in raising.

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、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基であり、Ｒ’は水素原子、炭素数１〜５のアルキル基、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, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms, and R ′ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or 1 to 1 carbon atoms. 5 is an alkoxy group or —COOR ″, wherein 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, A ″ is an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, 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 alkyl group having 1 to 5 carbon atoms of R ′ is the same as the alkyl group having 1 to 5 carbon atoms of 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 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 a fluorinated alkyl group Specific examples include groups in which one or more hydrogen atoms have been removed from a monocycloalkane such as cyclopentane or cyclohexane, or a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Etc.
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 which 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.
Specific examples of the structural units represented by the general formulas (a2-1) to (a2-5) are shown below.
In the following formula, R ^α represents a hydrogen atom, a methyl group or a trifluoromethyl group.

In the component (A1), as the structural unit (a2), one type of structural unit may be used, or two or more types may be used in combination.
Among the above, the structural unit (a2) is preferably at least one selected from the group consisting of structural units represented by the general formulas (a2-1) to (a2-5). -1) to (a2-3), at least one selected from the group consisting of structural units represented by (a2-3) is more preferable. Among them, structural units represented by chemical formulas (a2-1-1), (a2-2-1), (a2-2-7), (a2-3-1) and (a2-3-5) It is preferable to use at least one selected from the group consisting of

  The proportion of the structural unit (a2) in the component (A1) is preferably 5 to 60 mol%, more preferably 10 to 50 mol%, with respect to the total of all structural units constituting the component (A1). 50 mol% is more preferable. By setting it to the lower limit value of the range or more, the effect of having the structural unit (a2) can be sufficiently obtained, and by setting it to the upper limit value or less of the range, 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 (A) 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 cyclic aliphatic hydrocarbon group (cyclic group). The cyclic group may be a monocyclic group or a polycyclic group. For example, a resin for a resist composition for an ArF excimer laser can be appropriately selected from those proposed. The cyclic group is preferably a polycyclic group, and 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, the structural unit represented by the following formula (a3-1), the structural unit represented by the following formula (a3-2), and the following formula The structural unit represented by (a3-3) is preferable.

［式中、Ｒは前記と同じであり、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. In these, a 2-norbornyl group or a 3-norbornyl group is preferably 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%, based on the total of all structural units constituting the component (A1). 5 to 25 mol% is more preferable. The effect by having a structural unit (a3) as it is more than the lower limit of the said range is high, and the balance with another structural unit is favorable as it is below the upper limit of the said range.

<Structural unit (a4)>
The structural unit (a4) is a structural unit derived from an acrylate ester containing a non-acid-dissociable aliphatic polycyclic group.
Examples of the polycyclic group include those similar to those exemplified in the case of the structural unit (a1), for ArF excimer laser, for 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. ]

As the structural unit (a4), one type may be used alone, or two or more types may be used in combination.
When the component (A1) has the structural unit (a4), the proportion of the structural unit (a4) in the component (A1) is 1 to 30 mol% with respect to the total of all the structural units constituting the component (A1). Preferably, 10 to 20 mol% is more preferable.

<Structural unit (a6)>
The structural unit (a6) is a structural unit derived from styrene.
In the present invention, the structural unit (a6) is not essential, but when it is contained, the solubility in an alkali developer can be adjusted. Moreover, since dry etching tolerance improves, it is preferable.
In this specification, “styrene” is a concept including styrene and those in which the α-position hydrogen atom of styrene is substituted with another substituent such as an alkyl group.
“Structural unit derived from styrene” means a structural unit formed by cleavage of an ethylenic double bond of styrene. In styrene, the hydrogen atom of the phenyl group may be substituted with a substituent such as an alkyl group having 1 to 5 carbon atoms.
Preferred examples of the structural unit (a6) include structural units represented by general formula (a6-1) shown below.

［式（ａ６−１）中、Ｒ^１は前記と同じであり；Ｒ^７はハロゲン原子、炭素数１〜５のアルキル基又は炭素数１〜５のハロゲン化アルキル基であり；ｒは０〜３の整数である。］

[In formula (a6-1), R ¹ is as defined above; R ⁷ is a halogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms; It is an integer of 3. ]

In the general formula (a6-1), R ¹ is the same as R ¹ in the above formula (a5-1).
R ⁷ is the same as R ² in the above formula (a5-1).
r is an integer of 0 to 3, preferably 0 or 1, and industrially particularly preferably 0.
When r is 1, the substitution position of R ⁷ may be any of the o-position, m-position and p-position of the phenyl group.
When r is 2 or 3, arbitrary substitution positions can be combined. The plurality of R ⁷ may be the same or different.

As the structural unit (a6), one type may be used alone, or two or more types may be used in combination.
When the component (A1) has the structural unit (a6), the proportion of the structural unit (a6) in the component (A1) is 1 to 20 mol% with respect to the total of all the structural units constituting the component (A1). Preferably, 3-15 mol% is more preferable, and 5-15 mol% is further more preferable. The effect by having a structural unit (a6) as it is more than the lower limit of the said range is high, and the balance with another structural unit is favorable as it is below the upper limit of the said range.

<Structural unit (a7)>
The structural unit (a7) is a structural unit in which at least a part of hydrogen atoms in the hydroxyl group of the structural unit derived from hydroxystyrene is protected by a substituent.
In the structural unit (a7), examples of the substituent include a tertiary alkyl group-containing group, an alkoxyalkyl group, and an acid dissociable, dissolution inhibiting group (provided that the group is represented by the formula (a0-0-1)). And an organic group containing an acid dissociable, dissolution inhibiting group.

<Regarding the tertiary alkyl group-containing group>
In the present specification, the “tertiary alkyl group” refers to an alkyl group having a tertiary carbon atom. As described above, the “alkyl group” represents a monovalent saturated hydrocarbon group, and includes a chain (straight chain or branched chain) alkyl group and an alkyl group having a cyclic structure.
The “tertiary alkyl group-containing group” refers to a group containing a tertiary alkyl group in its structure. The tertiary alkyl group-containing group may be composed only of a tertiary alkyl group, or may be composed of a tertiary alkyl group and another atom or group other than the tertiary alkyl group. .
Examples of the “atom or group other than the tertiary alkyl group” that constitutes the tertiary alkyl group-containing group together with the tertiary alkyl group include a carbonyloxy group, a carbonyl group, an alkylene group, an oxygen atom, and the like. .

In the structural unit (a7), examples of the tertiary alkyl group-containing group include a tertiary alkyl group-containing group having no cyclic structure, a tertiary alkyl group-containing group having a cyclic structure, and the like.
The tertiary alkyl group-containing group having no cyclic structure is a group containing a branched tertiary alkyl group as the tertiary alkyl group and having no cyclic structure in the structure.
Examples of the branched tertiary alkyl group include groups represented by the following general formula (I).

In formula (I), R ^{21 to} R ²³ are each independently a linear or branched alkyl group. 1-5 are preferable and, as for carbon number of this alkyl group, 1-3 are more preferable.
Moreover, it is preferable that the total carbon number of group represented by general formula (I) is 4-7, it is more preferable that it is 4-6, and it is most preferable that it is 4-5.
Preferred examples of the group represented by the general formula (I) include a tert-butyl group and a tert-pentyl group, and a tert-butyl group is more preferable.

Examples of the tertiary alkyl group-containing group that does not have a cyclic structure include the above-described branched tertiary alkyl group; the above-described branched tertiary alkyl group is a linear or branched alkylene group A tertiary alkyl group-containing chain alkyl group bonded to the above; a tertiary alkyloxycarbonyl group having the branched tertiary alkyl group described above as the tertiary alkyl group; And tertiary alkyloxycarbonylalkyl groups having a branched tertiary alkyl group.
The alkylene group in the tertiary alkyl group-containing chain alkyl group is preferably an alkylene group having 1 to 5 carbon atoms, more preferably an alkylene group having 1 to 4 carbon atoms, and still more preferably an alkylene group having 2 to 2 carbon atoms.
Examples of the chain-like tertiary alkyloxycarbonyl group include a group represented by the following general formula (II). ^R 21 ^{to R 23} in the formula (II) is the same as ^R 21 ^{to R 23} in general formula (I). The chain-like tertiary alkyloxycarbonyl group is preferably a tert-butyloxycarbonyl group (t-boc) or a tert-pentyloxycarbonyl group.

Examples of the chain-like tertiary alkyloxycarbonylalkyl group include a group represented by the following general formula (III). ^R 21 ^{to R 23} in the formula (III) are the same as ^R 21 ^{to R 23} in general formula (I). f is an integer of 1 to 3, and 1 or 2 is preferable. As the chain-like tertiary alkyloxycarbonylalkyl group, a tert-butyloxycarbonylmethyl group and a tert-butyloxycarbonylethyl group are preferable.
Of these, the tertiary alkyl group-containing group having no cyclic structure is preferably a tertiary alkyloxycarbonyl group or a tertiary alkyloxycarbonylalkyl group, more preferably a tertiary alkyloxycarbonyl group. A tert-butyloxycarbonyl group (t-boc) is most preferred.

The tertiary alkyl group-containing group having a cyclic structure is a group having a tertiary carbon atom and a cyclic structure in the structure.
In the tertiary alkyl group-containing group having a cyclic structure, the cyclic structure preferably has 4 to 12 carbon atoms, more preferably 5 to 10 carbon atoms, and more preferably 6 to 10 carbon atoms constituting the ring. Most preferred. Examples of the cyclic structure include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane. Preferable 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 tertiary alkyl group-containing group having a cyclic structure include a group having the following group (1) or (2) as a tertiary alkyl group.
(1) A group in which a linear or branched alkyl group is bonded to a carbon atom constituting a ring of a cyclic alkyl group (cycloalkyl group), and the carbon atom is a tertiary carbon atom.
(2) A group in which an alkylene group having a tertiary carbon atom (branched alkylene group) is bonded to the carbon atom constituting the ring of the cycloalkyl group.

The linear or branched alkyl group in the group (1) preferably has 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms. .
Examples of the group (1) include a 2-methyl-2-adamantyl group, a 2-ethyl-2-adamantyl group, a 1-methyl-1-cycloalkyl group, and a 1-ethyl-1-cycloalkyl group.
That is, in terms of the general formula, the tertiary alkyl group-containing group having the cyclic structure according to (1) is preferably a group represented by the following formula (p0), represented by the following formula (p0-1). What is represented is more preferable, and what is represented by a following formula (p0-1-1) is still more preferable.

［式中、Ｙ^２は単結合、または上記式（ａ１−０−２）におけるＹ^２と同様の２価の連結基であり、Ｒ^１４は炭素数１〜５のアルキル基であり、Ｒ^ｃは当該Ｒ^ｃが結合している炭素原子と共に脂肪族環式基を形成する基である。］

[Wherein Y ² is a single bond or a divalent linking group similar to Y ² in formula (a1-0-2), R ¹⁴ is an alkyl group having 1 to 5 carbon atoms, and R ^c Is a group which forms an aliphatic cyclic group together with the carbon atom to which R ^c is bonded. ]

Examples of R ^c include the same as the above aliphatic cyclic group, and a polycyclic aliphatic cyclic group is preferable.

［式中、Ｒ^１３は水素原子またはメチル基であり、Ｒ^１４は炭素数１〜５のアルキル基であり、Ｒ^ｃは当該Ｒ^ｃが結合している炭素原子と共に脂肪族環式基を形成する基である。］

[Wherein R ¹³ is a hydrogen atom or a methyl group, R ¹⁴ is an alkyl group having 1 to 5 carbon atoms, and R ^c forms an aliphatic cyclic group together with the carbon atom to which R ^c is bonded. It is a group to do. ]

［式中、Ｒ^１３は水素原子またはメチル基であり、Ｒ^１４は炭素数１〜５のアルキル基である。］

[Wherein, R ¹³ represents a hydrogen atom or a methyl group, and R ¹⁴ represents an alkyl group having 1 to 5 carbon atoms. ]

In the above (2), the cycloalkyl group to which the branched alkylene group is bonded may have a substituent. Examples of the substituent include a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, and an oxygen atom (= O).
Examples of the group (2) include groups represented by the following chemical formula (IV).

In the formula (IV), R ²⁴ is a cycloalkyl group which may or may not have a substituent. Examples of the substituent that the cycloalkyl group may have include a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, and an oxygen atom (═O).
R ²⁵ and R ²⁶ are each independently a linear or branched alkyl group.
Examples of the alkyl group include the same alkyl groups as R ^{21 to} R ²³ in the formula (I).

<Alkoxyalkyl group>
In the structural unit (a7), examples of the alkoxyalkyl group include groups represented by general formula (V) shown below.

In formula (V), R ⁵¹ is a linear, branched or cyclic alkyl group.
When R ⁵¹ 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 ⁵¹ 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. For example, one or more hydrogen atoms from a polycycloalkane such as monocycloalkane, bicycloalkane, tricycloalkane, tetracycloalkane, which may or may not be substituted with a fluorine atom or a fluorinated alkyl group And the like except for. 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. . Among them, a group obtained by removing one or more hydrogen atoms from adamantane is preferable.
R ⁵² is a linear or branched alkylene group. The alkylene group preferably has 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms, and still more preferably 1 to 2 carbon atoms.
Among the above, the alkoxyalkyl group is particularly preferably a group represented by the following general formula (VI).

In formula (VI), R ⁵¹ is the same as defined above, and R ⁵³ and R ⁵⁴ each independently represent a linear or branched alkyl group or a hydrogen atom.
In R ⁵³ and R ⁵⁴ , 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 ⁵³ and R ⁵⁴ is a hydrogen atom and the other is a methyl group.

<About acid dissociable, dissolution inhibiting group>
In the structural unit (a7), the acid dissociable, dissolution inhibiting group is not particularly limited as long as it is other than the group represented by the formula (a0-0-1). For example, for KrF excimer laser, ArF excimer laser, etc. Among the resins for resist compositions, a number of proposed resins can be appropriately selected and used. Specific examples include those exemplified in the following acid dissociable, dissolution inhibiting group (VII).

  Examples of the acid dissociable, dissolution inhibiting group (VII) include a group represented by the following general formula (VII-a) and a group represented by the following general formula (VII-b).

［式（ＶＩＩ−ａ）中、Ｒ^２７は直鎖状又は分岐鎖状のアルキレン基を表し；Ｘ^０は脂肪族環式基、芳香族環式炭化水素基又は炭素数１〜５のアルキル基を表す。式（ＶＩＩ−ｂ）中、Ｘ^０は前記式（ＶＩＩ−ａ）におけるＸ^０と同じであり；Ｒ^４は水素原子若しくは炭素数１〜５のアルキル基を表し、又は、Ｘ^０およびＲ^４がそれぞれ独立に炭素数１〜５のアルキレン基であって、Ｘ^０の末端とＲ^４の末端とが結合していてもよく；Ｒ^５は水素原子又は炭素数１〜５のアルキル基を表す。］

[In the formula (VII-a), R ²⁷ represents a linear or branched alkylene group; X ⁰ is an aliphatic cyclic group, an aromatic cyclic hydrocarbon group or an alkyl group having 1 to 5 carbon atoms. Represents. In Formula (VII-b), X ⁰ is the same as X ⁰ in Formula (VII-a); R ⁴ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, or X ⁰ and R ⁴ Each independently represents an alkylene group having 1 to 5 carbon atoms, and the end of X ⁰ may be bonded to the end of R ⁴ ; R ⁵ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. . ]

In the general formula (VII-a), R ²⁷ represents a linear or branched alkylene group.
The alkylene group preferably has 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms, and still more preferably 1 to 2 carbon atoms.

In the formulas (VII-a) and (VII-b), X ⁰ each independently represents an aliphatic cyclic group, an aromatic cyclic hydrocarbon group, or an alkyl group having 1 to 5 carbon atoms.
The aliphatic cyclic group for X ⁰ is a monovalent aliphatic cyclic group. The aliphatic cyclic group can be appropriately selected from, for example, those proposed in a number of conventional ArF resists. Specific examples of the aliphatic cyclic group include an aliphatic monocyclic group having 5 to 7 carbon atoms and an aliphatic polycyclic group having 10 to 16 carbon atoms.
Examples of the aliphatic monocyclic group having 5 to 7 carbon atoms include groups in which one hydrogen atom has been removed from a monocycloalkane, specifically, one hydrogen atom has been removed from cyclopentane, cyclohexane and the like. Group.
Examples of the aliphatic polycyclic group having 10 to 16 carbon atoms include groups in which one hydrogen atom has been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like. Specific examples include groups in which one hydrogen atom has been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among these, an adamantyl group, norbornyl group, and tetracyclododecanyl group are industrially preferable, and an adamantyl group is particularly preferable.
Examples of the aromatic cyclic hydrocarbon group for X ⁰ include aromatic polycyclic groups having 10 to 16 carbon atoms. Specific examples include groups in which one hydrogen atom has been removed from naphthalene, anthracene, phenanthrene, pyrene, and the like. Specific examples include 1-naphthyl group, 2-naphthyl group, 1-anthryl group, 2-anthryl group, 1-phenanthryl group, 2-phenanthryl group, 3-phenanthryl group, 1-pyrenyl group, and the like. A naphthyl group is particularly preferred industrially.
Examples of the alkyl group having 1 to 5 carbon atoms of X ⁰ include the same as the alkyl group having 1 to 5 carbon atoms which may be bonded to the α-position of the hydroxystyrene, and a methyl group or an ethyl group is more preferable. The ethyl group is most preferred.

In the formula (VII-b), the alkyl group of 1 to 5 carbon atoms for ^{R 4,} the same alkyl group of 1 to 5 carbon atoms in the ^{X 0} and the like. Industrially, a methyl group or an ethyl group is preferable, and a methyl group is particularly preferable.
R ⁵ represents an alkyl group having 1 to 5 carbon atoms or a hydrogen atom. The alkyl group of 1 to 5 carbon atoms for R ^5, the same as the alkyl group having 1 to 5 carbon atoms for ^{R 4.} R ⁵ is preferably industrially a hydrogen atom.
In particular, it is preferable that either one of R ⁴ and R ⁵ is a hydrogen atom and the other is a methyl group.

In the general formula (VII-b), X ⁰ and R ⁴ are each independently an alkylene group having 1 to 5 carbon atoms, and the end of X ^{0 and} the end of R ⁴ are bonded to each other. Also good.
In this case, in the general formula (VII-b), a cyclic group is formed by R ⁴ , X ⁰ , the oxygen atom to which X ⁰ is bonded, and the carbon atom to which the oxygen atom and R ⁴ are bonded. ing.
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 acid dissociable, dissolution inhibiting group (VII), it is preferable that R ⁵ is a hydrogen atom and R ⁴ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms because of excellent resist pattern shape and the like. .
Specific examples of the acid dissociable, dissolution inhibiting group (VII) include, for example, a group in which X ⁰ is an alkyl group having 1 to 5 carbon atoms, that is, a 1-alkoxyalkyl group includes a 1-methoxyethyl group, 1-ethoxyethyl group. Group, 1-iso-propoxyethyl group, 1-n-butoxyethyl group, 1-tert-butoxyethyl group, methoxymethyl group, ethoxymethyl group, iso-propoxymethyl group, n-butoxymethyl group, tert-butoxymethyl Groups and the like.
In addition, examples of the group in which X ⁰ is an aliphatic cyclic group include a 1-cyclohexyloxyethyl group, a 1- (2-adamantyl) oxymethyl group, and 1- (represented by the following formula (VII-a-1). 1-adamantyl) oxyethyl group and the like.
Examples of the group in which X ⁰ is an aromatic cyclic hydrocarbon group include a 1- (2-naphthyl) oxyethyl group represented by the following formula (VII-b-1).
Of these, a 1-ethoxyethyl group is particularly preferable.

<Organic group containing acid dissociable, dissolution inhibiting group>
In this specification, “an organic group containing an acid dissociable, dissolution inhibiting group” means an acid dissociable, dissolution inhibiting group, a group or an atom that is not dissociated by an acid (that is, an acid dissociable, dissolution inhibiting group that is not dissociated by an acid, Means a group composed of (A1) a group or atom that remains bonded to the component even after dissociation.

  The organic group containing an acid dissociable, dissolution inhibiting group is not particularly limited. For example, a resin for resist compositions such as for KrF excimer laser and ArF excimer laser is appropriately selected and used. be able to. Specific examples include organic groups having the acid dissociable, dissolution inhibiting groups listed above. Examples include organic groups having the following acid dissociable, dissolution inhibiting groups as organic groups having acid dissociable, dissolution inhibiting groups (VII). (VIII).

Examples of the organic group (VIII) having an acid dissociable, dissolution inhibiting group include groups represented by the following general formula (VIII).
In the organic group (VIII) having such a structure, when an acid is generated from the component (B) by exposure, the acid causes an oxygen atom bonded to Q and a carbon atom to which R ⁴ and R ⁵ are bonded. The bond is broken and —C (R ⁴ ) (R ⁵ ) —OX ⁰ is dissociated.

［式（ＶＩＩＩ）中、Ｘ^０は脂肪族環式基、芳香族環式炭化水素基または炭素数１〜５のアルキル基を表し；Ｒ^４は水素原子若しくは炭素数１〜５のアルキル基を表し、又は、Ｘ^０およびＲ^４がそれぞれ独立に炭素数１〜５のアルキレン基であって、Ｘ^０の末端とＲ^４の末端とが結合していてもよく；Ｒ^５は炭素数１〜５のアルキル基または水素原子を表し；Ｑは２価の脂肪族環式基を表す。］

[In the formula (VIII), X ⁰ represents an aliphatic cyclic group, an aromatic cyclic hydrocarbon group or an alkyl group having 1 to 5 carbon atoms; R ⁴ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; It represents or an alkylene group having 1 to 5 carbon atoms ^{X 0} and ^{R 4} each independently may be bonded to the distal end and ^{R 4} of ^{X 0; R 5} is 1 to carbon atoms 5 represents an alkyl group or a hydrogen atom; Q represents a divalent aliphatic cyclic group. ]

In the general formula ^(VIII), as the ^{X 0, R 4, R 5} , respectively the same as ^{X 0, R 4,} R ⁵ in the general formula (VII-b).
Examples of the divalent aliphatic cyclic group for Q, include further groups in which one hydrogen atom has been removed from an aliphatic cyclic group for the X ^0.

  Among these, the hydrogen atom in the hydroxyl group of the structural unit (a7) is preferably protected by substitution with a tertiary alkyl group-containing group, and is represented by the general formula (II) or (p0). It is more preferred that the group is protected by substitution with a group.

  Among the structural units (a7), preferred are structural units represented by general formula (a7-1) shown below.

［式（ａ７−１）中、Ｒ^１、Ｒ^２およびｑは上記と同じであり、ｐ’は１〜３の整数である。ただし、ｐ’＋ｑは１以上５以下である。Ｚは第３級アルキル基含有基、アルコキシアルキル基、酸解離性溶解抑制基（ただし、前記式（ａ０−０−１）で表される基を除く。）又は酸解離性溶解抑制基を含む有機基である。］

[In formula (a7-1), R ¹ , R ² and q are the same as above, and p ′ is an integer of 1 to 3. However, p ′ + q is 1 or more and 5 or less. Z includes a tertiary alkyl group-containing group, an alkoxyalkyl group, an acid dissociable, dissolution inhibiting group (excluding the group represented by the formula (a0-0-1)) or an acid dissociable, dissolution inhibiting group. Organic group. ]

In the formula (a7-1), R ¹ , R ² and q are the same as R ¹ , R ² and q in the formula (a5-1), respectively.
p ′ is an integer of 1 to 3, preferably 1.
The bonding position of —OZ may be any of the o-position, m-position, and p-position of the phenyl group. When p is 1, the p-position is preferred because it is readily available and inexpensive. When p is 2 or 3, arbitrary substitution positions can be combined.
However, p ′ + q is 1 or more and 5 or less.
Z represents a tertiary alkyl group-containing group, an alkoxyalkyl group, an acid dissociable, dissolution inhibiting group (excluding the group represented by the formula (a0-0-1)) or an acid dissociable, dissolution inhibiting group. Examples of the organic group include the same as those described above. Among them, a tertiary alkyl group-containing group is preferable, a group represented by the general formula (II) is more preferable, and a tert-butyloxycarbonyl group (t-boc) is particularly preferable.

As the structural unit (a7), one type of structural unit may be used alone, or two or more types of structural units may be used in combination.
When the component (A1) has the structural unit (a7), the proportion of the structural unit (a7) in the component (A1) is 1 to 40 mol% with respect to the total of all the structural units constituting the component (A1). Preferably, it is 5 to 40 mol%, more preferably 15 to 40 mol%, still more preferably 20 to 40 mol%. By setting it as more than the lower limit of the said range, the solubility to an organic solvent improves, and when it is below the upper limit of the said range, the balance with another structural unit is favorable.

  In the present invention, the component (A1) is a polymer having a structural unit (a0). Examples of such a polymer include a polymer having a structural unit (a0-5) and a structural unit (a0-1). And a copolymer having a structural unit (a0-5) and a structural unit (a0-1).

  Specific examples of the polymer having the structural unit (a0-5) include a copolymer having the structural unit (a0-5) and the structural unit (a5), a structural unit (a0-5), and a structural unit ( a5) a copolymer having a structural unit (a1), a structural unit (a0-5), a structural unit (a5), a copolymer having a structural unit (a1) and a structural unit (a6), a structural unit ( a0-5), a copolymer having a structural unit (a5) and a structural unit (a7), a copolymer having a structural unit (a0-5), a structural unit (a5), and a structural unit (a6), And a copolymer having the unit (a0-5), the structural unit (a5), the structural unit (a7), and the structural unit (a6).

  Specifically, as the polymer having the structural unit (a0-1), for example, a copolymer having the structural unit (a0-1) and the structural unit (a1), the structural unit (a0-1) and the structural unit ( a copolymer having a structural unit (a0-1) and a structural unit (a3), a structural unit (a0-1), a structural unit (a2), and a structural unit (a3). Copolymer having structural unit (a0-1), structural unit (a1) and structural unit (a2), structural unit (a0-1), structural unit (a1) and structural unit (a3) A copolymer having a structural unit (a0-1), a structural unit (a1), a structural unit (a2), and a structural unit (a3), a structural unit (a0-1) and a structural unit ( a5), a structural unit (a0-1), a structural unit (a5) and a structural unit ( 6), a copolymer having the structural unit (a0-1), the structural unit (a5), and the structural unit (a1), the structural unit (a0-1), the structural unit (a5), and the structural unit. Examples thereof include a copolymer having a unit (a1) and a structural unit (a6).

  Specific examples of the copolymer having the structural unit (a0-5) and the structural unit (a0-1) include, for example, the structural unit (a0-5), the structural unit (a0-1), and the structural unit (a6). And a copolymer having a structural unit (a0-5), a structural unit (a0-1), a structural unit (a7), and a structural unit (a6).

In the component (A), as the component (A1), one type may be used alone, or two or more types may be used in combination.
Among these, the component (A1) preferably has the structural unit (a5) and the structural unit (a0-5) because the effects of the present invention are particularly good. A copolymer having the unit (a0-5) is particularly preferred, and a copolymer comprising the structural unit (a5) and the structural unit (a0-5) is most preferred.
In the present invention, the component (A1) preferably includes the following combination of structural units.

［式（Ａ１−１１）中、Ｒ^１’は水素原子又は炭素数１〜５のアルキル基を表し、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。Ｒ^１は前記と同じである。］

[In formula (A1-11), R ¹ ′ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and A ′ represents an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, An oxygen atom or a sulfur atom. R ¹ is the same as described above. ]

In said formula (A1-11), R < ¹ '> represents a hydrogen atom or a C1-C5 alkyl group, and a hydrogen atom or a methyl group is preferable.
A ′ is an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, an oxygen atom or a sulfur atom, preferably an oxygen atom or an alkylene group having 1 to 5 carbon atoms, A C 1-3 alkylene group is more preferred, and an oxygen atom or a methylene group is more preferred.
R ¹ is the same as described above, and is preferably a hydrogen atom or a methyl group. Several R < ¹ > may mutually be the same and may differ.

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 into which a hydroxyalkyl group in which a part of hydrogen atoms in an alkyl group is substituted with a fluorine atom is introduced has a LWR (line width roughness: a phenomenon in which the line width of a line pattern becomes nonuniform). Effective for reduction. Further, it is effective for reducing development defects and LER (line edge roughness: uneven unevenness of line side walls).
In addition, when the component (A1) has a structural unit derived from hydroxystyrene, it can be obtained, for example, by reacting polyhydroxystyrene with a vinyl ether compound containing a “—Y ¹ -R ³ ” structure. it can.

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

  In the component (A), as the component (A2), one type may be used alone, or two or more types may be used in combination.

In the positive resist composition of the present invention, as the component (A), one type may be used alone, or two or more types may be used in combination.
In the positive 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>
The component (B) is not particularly limited, and those that have been proposed as acid generators for chemically amplified resists 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, and poly (bissulfonyl) diazomethanes. 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.

［式中、Ｒ^１”〜Ｒ^３”，Ｒ^５”〜Ｒ^６”は、それぞれ独立に、アリール基またはアルキル基を表し；式（ｂ−１）におけるＲ^１”〜Ｒ^３”のうち、いずれか２つが相互に結合して式中のイオウ原子と共に環を形成してもよく；Ｒ^４”は、置換基を有していてもよいアルキル基、ハロゲン化アルキル基、アリール基、またはアルケニル基を表し；Ｒ^１”〜Ｒ^３”のうち少なくとも１つはアリール基を表し、Ｒ^５”〜Ｒ^６”のうち少なくとも１つはアリール基を表す。］

[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 may be bonded to each other to form a ring together with the sulfur atom in the formula; R ⁴ ″ may be an optionally substituted alkyl group, halogenated alkyl group, aryl group, or alkenyl group; Represents at least one of R ¹ ″ to 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 of 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 or alkoxy. 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, ethyl group, propyl group, n-butyl group, or 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, A tert-butoxy group is particularly preferable, and a methoxy group and an ethoxy group are most preferable.
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 each preferably a phenyl group or a naphthyl group.

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 are the same as the aryl groups of R ¹ ″ to R ³ ″.

Preferable examples of the cation moiety of the compound represented by the formula (b-1) include cation moieties represented by the following formulas (I-1-1) to (I-1-10). Among these, those having a triphenylmethane skeleton such as a cation moiety represented by formulas (I-1-1) to (I-1-8) are preferable.
In the following formulas (I-1-9) to (I-1-10), R ⁹ and R ¹⁰ are each independently a phenyl group, naphthyl group or carbon number 1 to 5 which may have a substituent. An alkyl group, an alkoxy group, and a hydroxyl group.
d is an integer of 1 to 3, and 1 or 2 is most preferable.

R ⁴ ″ represents an alkyl group, a halogenated alkyl group, an aryl group, or an alkenyl group which may have a substituent.

The alkyl group for R ⁴ ″ may be linear, branched or cyclic.
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.

Examples of the halogenated alkyl group for R ⁴ ″ include groups in which part or all of the hydrogen atoms of the linear, branched, or cyclic alkyl group have been substituted with halogen atoms. A fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned, A fluorine atom is preferable.
For example, when R ⁴ ″ is a fluorinated alkyl group, the number of carbon atoms is preferably 1 to 10, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
In the halogenated alkyl group represented by R ⁴ ″, the ratio of the number of halogen atoms to the total number of halogen atoms and hydrogen atoms contained in the halogenated alkyl group (halogenation rate (%)) is 10 to 100%. The higher the halogenation rate, the higher the strength of the acid, and the more preferable it is.
For example, when R ⁴ ″ is a fluorinated alkyl group, the fluorination rate (ratio of fluorine atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%, and particularly all the hydrogen atoms A fluorinated alkyl group (perfluoroalkyl group) substituted with a fluorine atom is preferable because the strength of the acid is increased.

The aryl group for R ⁴ ″ is preferably an aryl group having 6 to 20 carbon atoms.
The alkenyl group in R ⁴ ″ is preferably an alkenyl group having 2 to 10 carbon atoms.

In the above R ⁴ ″, “optionally substituted” means one of hydrogen atoms in the linear, branched or cyclic alkyl group, halogenated alkyl group, aryl group, or alkenyl group. It means that part or all may be substituted with a substituent (an atom or group other than a hydrogen atom).
The number of substituents in R ⁴ ″ may be one or two or more.

Examples of the substituent include a halogen atom, a hetero atom, an alkyl group, a formula: X ⁵ -Q ^1- [where Q ¹ is a divalent linking group containing an oxygen atom, and X ⁵ represents a substituent. It is a C3-C30 hydrocarbon group which may have. ] Etc. which are represented by these.
Examples of the halogen atom and alkyl group include the same groups as those described as the halogen atom and alkyl group in the halogenated alkyl group in R ⁴ ″.
Examples of the hetero atom include an oxygen atom, a nitrogen atom, and a sulfur atom.

In the group represented by X ⁵ -Q ^1- , Q ¹ is a divalent linking group containing an oxygen atom.
Q ¹ may contain an atom other than an oxygen atom. Examples of atoms other than oxygen atoms include carbon atoms, hydrogen atoms, oxygen atoms, sulfur atoms, and nitrogen atoms.
Examples of the divalent linking group containing an oxygen atom include an oxygen atom (ether bond; —O—), an ester bond (—C (═O) —O—), and an amide bond (—C (═O) —NH. -), A carbonyl group (-C (= O)-), a non-hydrocarbon oxygen atom-containing linking group such as a carbonate bond (-O-C (= O) -O-); the non-hydrocarbon oxygen atom Examples include a combination of a containing linking group and an alkylene group.
Examples of the combination include —R ⁹¹ —O—, —R ⁹² —O—C (═O) —, —C (═O) —O—R ⁹³ —O—C (═O) — , R ^{91 to} R ⁹³ are each independently an alkylene group.) And the like.
The alkylene group for R ^{91 to} R ⁹³ is preferably a linear or branched alkylene group, and the alkylene group preferably has 1 to 12 carbon atoms, more preferably 1 to 5 carbon atoms, and particularly preferably 1 to 3 carbon atoms. 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 — and the like. Alkylethylene groups; trimethylene groups (n-propylene groups) [—CH ₂ CH ₂ CH ₂ —]; alkyls such as —CH (CH ₃ ) CH ₂ CH ₂ — and —CH ₂ CH (CH ₃ ) CH ₂ — trimethylene; tetramethylene group _[-CH 2 _CH 2 C _{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; pentamethylene group _[-CH 2 _CH 2 CH ₂ CH ₂ CH ₂ —] and the like.
Q ¹ is preferably a divalent linking group containing an ester bond or an ether bond, and in particular, —R ⁹¹ —O—, —R ⁹² —O—C (═O) — or —C (═O) — O—R ⁹³ —O—C (═O) — is preferred.

In the group represented by X ⁵ -Q ^1- , the hydrocarbon group for X ⁵ may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group.

The aromatic hydrocarbon group for X ⁵ is a hydrocarbon group having an aromatic ring. The aromatic hydrocarbon group preferably has 3 to 30 carbon atoms, more preferably 5 to 30, more preferably 5 to 20, particularly preferably 6 to 15, and most preferably 6 to 12. However, the carbon number does not include the carbon number in the substituent.
Specific examples of the aromatic hydrocarbon group include a hydrogen atom from an aromatic hydrocarbon ring such as a phenyl group, a biphenyl group, a fluorenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. Examples include aryl groups such as aryl group, benzyl group, phenethyl group, 1-naphthylmethyl group, 2-naphthylmethyl group, 1-naphthylethyl group, 2-naphthylethyl group, etc., from which one is removed. The number of carbon atoms of the alkyl chain in the arylalkyl group is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1.

The aromatic hydrocarbon group may have a substituent. For example, a part of carbon atoms constituting the aromatic ring of the aromatic hydrocarbon group may be substituted with a hetero atom, and the hydrogen atom bonded to the aromatic ring of the aromatic hydrocarbon group is substituted with the substituent. May be.
Examples of the former include heteroaryl groups in which some of the carbon atoms constituting the ring of the aryl group are substituted with heteroatoms such as oxygen atoms, sulfur atoms and nitrogen atoms, and aromatic hydrocarbons in the arylalkyl groups Examples include heteroarylalkyl groups in which some of the carbon atoms constituting the ring are substituted with the above heteroatoms.
Examples of the substituent of the aromatic hydrocarbon group in the latter example include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, and an oxygen atom (═O).
The alkyl group as a substituent of the aromatic hydrocarbon group is preferably an alkyl group having 1 to 5 carbon atoms, and most preferably a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group. preferable.
The alkoxy group as a substituent of the aromatic hydrocarbon group is preferably an alkoxy group having 1 to 5 carbon atoms, and is a methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, tert- A butoxy group is preferable, and a methoxy group and an ethoxy group are most preferable.
Examples of the halogen atom as a substituent for the aromatic hydrocarbon group include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is preferable.
Examples of the halogenated alkyl group as the substituent of the aromatic hydrocarbon group include groups in which part or all of the hydrogen atoms of the alkyl group have been substituted with the halogen atoms.

The aliphatic hydrocarbon group for X ⁵ may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be linear, branched or cyclic.
In X ⁵ , the aliphatic hydrocarbon group may be a group in which a part of carbon atoms constituting the aliphatic hydrocarbon group may be substituted with a substituent containing a hetero atom, and hydrogen constituting the aliphatic hydrocarbon group A part or all of the atoms may be substituted with a substituent containing a hetero atom.
The “heteroatom” in X ⁵ is not particularly limited as long as it is an atom other than a carbon atom and a hydrogen atom, and examples thereof include a halogen atom, an oxygen atom, a sulfur atom, and a nitrogen atom.
Examples of the halogen atom include a fluorine atom, a chlorine atom, an iodine atom, and a bromine atom.
The substituent containing a hetero atom may be composed only of the hetero atom, or may be a group containing a group or atom other than the hetero atom.
Specific examples of the substituent for substituting a part of carbon atoms include, for example, —O—, —C (═O) —O—, —C (═O) —, —O—C (═O) —O. -, - C (= O) -NH -, - NH- (H is an alkyl group, may be substituted with a substituent such as an acyl group), - S -, - S (= O) 2 -, - S (= O) ₂ —O— and the like can be mentioned. When the aliphatic hydrocarbon group is cyclic, these substituents may be included in the ring structure.
Specific examples of the substituent that substitutes part or all of the hydrogen atoms include an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, an oxygen atom (═O), and a cyano group.
The alkoxy group is preferably an alkoxy group having 1 to 5 carbon atoms, preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, or a tert-butoxy group, and a methoxy group or an ethoxy group. Is most preferred.
As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned, A fluorine atom is preferable.
As the halogenated alkyl group, a part or all of hydrogen atoms of an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a tert-butyl group, etc. And a group substituted with a halogen atom.

Examples of the aliphatic hydrocarbon group include a linear or branched saturated hydrocarbon group, a linear or branched monovalent unsaturated hydrocarbon group, or a cyclic aliphatic hydrocarbon group (aliphatic ring). Formula group) is preferred.
The linear saturated hydrocarbon group (alkyl group) preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and most preferably 1 to 10 carbon atoms. Specifically, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decanyl group, undecyl group, dodecyl group, tridecyl group, isotridecyl group, tetradecyl group Group, pentadecyl group, hexadecyl group, isohexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group and the like.
The branched saturated hydrocarbon group (alkyl group) preferably has 3 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and most preferably 3 to 10 carbon atoms. Specifically, for example, 1-methylethyl group, 1-methylpropyl group, 2-methylpropyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylbutyl group, 2-ethylbutyl group, Examples include 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group and the like.

As an unsaturated hydrocarbon group, it is preferable that carbon number is 2-10, 2-5 are preferable, 2-4 are preferable, and 3 is especially preferable. Examples of the linear monovalent unsaturated hydrocarbon group include a vinyl group, a propenyl group (allyl group), and a butynyl group. Examples of the branched monovalent unsaturated hydrocarbon group include a 1-methylpropenyl group and a 2-methylpropenyl group.
Among the above, the unsaturated hydrocarbon group is particularly preferably a propenyl group.

The aliphatic cyclic group may be a monocyclic group or a polycyclic group. The number of carbon atoms is preferably 3 to 30, more preferably 5 to 30, further preferably 5 to 20, particularly preferably 6 to 15, and most preferably 6 to 12.
Specifically, for example, a group in which one or more hydrogen atoms have been removed from a monocycloalkane; a group in which one or more hydrogen atoms have been removed from a polycycloalkane such as bicycloalkane, tricycloalkane, tetracycloalkane, etc. Can be mentioned. More specifically, a group in which one or more hydrogen atoms have been removed from a monocycloalkane such as cyclopentane or cyclohexane; one or more polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Examples include a group excluding a hydrogen atom.
When the aliphatic cyclic group does not contain a substituent containing a hetero atom in the ring structure, the aliphatic cyclic group is preferably a polycyclic group, and one or more hydrogen atoms from the polycycloalkane are substituted. Excluded groups are preferred, and groups obtained by removing one or more hydrogen atoms from adamantane are most preferred.
When the aliphatic cyclic group includes a substituent containing a hetero atom in the ring structure, examples of the substituent containing a hetero atom include —O—, —C (═O) —O—, —S—. , —S (═O) ₂ — and —S (═O) ₂ —O— are preferable. Specific examples of the aliphatic cyclic group include the following formulas (L1) to (L5), (S1) to (S4), and the like.
In these aliphatic cyclic groups, a part of hydrogen atoms bonded to carbon atoms constituting the ring structure may be substituted with a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, and an oxygen atom (═O).
The alkyl group is preferably an alkyl group having 1 to 5 carbon atoms, particularly preferably a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group.
Examples of the alkoxy group and the halogen atom are the same as those exemplified as the substituent for substituting part or all of the hydrogen atoms.

［式中、Ｑ”は炭素数１〜５のアルキレン基、−Ｏ−、−Ｓ−、−Ｏ−Ｒ^９４−または−Ｓ−Ｒ^９５−であり、Ｒ^９４およびＲ^９５はそれぞれ独立に炭素数１〜５のアルキレン基であり、ｍは０または１の整数である。］

[Wherein, Q ″ is an alkylene group having 1 to 5 carbon atoms, —O—, —S—, —O—R ⁹⁴ — or —S—R ⁹⁵ —, wherein R ⁹⁴ and R ⁹⁵ are each independently carbon. An alkylene group of 1 to 5 and m is an integer of 0 or 1.]

In the formula, each of the alkylene groups for Q ″, R ⁹⁴ and R ⁹⁵ is preferably a linear or branched alkylene group, and the alkylene group preferably has 1 to 12 carbon atoms, preferably 1 to 5 carbon atoms. More preferably, 1 to 3 is particularly 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 — and the like. Alkylethylene groups; trimethylene groups (n-propylene groups) [—CH ₂ CH ₂ CH ₂ —]; alkyls such as —CH (CH ₃ ) CH ₂ CH ₂ — and —CH ₂ CH (CH ₃ ) CH ₂ — trimethylene; tetramethylene group _[-CH 2 _CH 2 C _{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; pentamethylene group _[-CH 2 _CH 2 CH ₂ CH ₂ CH ₂ —] and the like.

Among the above, X ⁵ is preferably a cyclic group which may have a substituent. The cyclic group may be an aromatic hydrocarbon group which may have a substituent, an aliphatic cyclic group which may have a substituent, or a substituent. It is preferably an aliphatic cyclic group that may be used.
The aromatic hydrocarbon group is preferably a naphthyl group which may have a substituent or a phenyl group which may have a substituent.
As the aliphatic cyclic group which may have a substituent, a polycyclic aliphatic cyclic group which may have a substituent is preferable. The polycyclic aliphatic cyclic group is a group obtained by removing one or more hydrogen atoms from the polycycloalkane, and is represented by the formulas (L2) to (L5) and (S3) to (S4). Groups and the like are preferred.

In the present invention, R ⁴ ″ preferably has X ⁵ -Q ^1- as a substituent. In this case, R ⁴ ″ is X ⁵ -Q ¹ -Y ^3- [wherein Q ¹ and X ^{1 5} is the same as above, and Y ³ is an optionally substituted alkylene group having 1 to 4 carbon atoms or an optionally substituted fluorinated alkylene group having 1 to 4 carbon atoms. . ] Is preferable.
In the group represented by X ⁵ -Q ¹ -Y ^3- , the alkylene group for Y ³ includes the same alkylene groups as those described above for Q ¹ having 1 to 4 carbon atoms.
Examples of the fluorinated alkylene group for Y ³ include groups in which some or all of the hydrogen atoms of the alkylene group have been substituted with fluorine atoms.
As Y ^3, _{specifically, -CF 2 -, - CF 2} CF 2 -, - CF 2 CF 2 CF 2 -, - CF (CF 3) CF 2 -, - CF (CF 2 CF 3) -, _{-C (CF 3) 2 -,} - CF 2 CF 2 CF 2 CF 2 -, - CF (CF 3) CF 2 CF 2 -, - CF 2 CF (CF 3) CF 2 -, - CF (CF 3) CF (CF ₃ ) —, —C (CF ₃ ) ₂ CF ₂ —, —CF (CF ₂ CF ₃ ) CF ₂ —, —CF (CF ₂ CF ₂ CF ₃ ) —, —C (CF ₃ ) (CF _{2 CF 3) -; - CHF} -, - CH 2 CF 2 -, - CH 2 CH 2 CF 2 -, - CH 2 CF 2 CF 2 -, - CH (CF 3) CH 2 -, - CH (CF 2 _{CF 3) -, - C (} CH 3) (CF 3) -, - CH 2 CH 2 CH 2 CF 2 -, - C H ₂ CH ₂ CF ₂ CF ₂ —, —CH (CF ₃ ) CH ₂ CH ₂ —, —CH ₂ CH (CF ₃ ) CH ₂ —, —CH (CF ₃ ) CH (CF ₃ ) —, —C ( _{CF 3) 2 CH 2 -;} - CH 2 -, - CH 2 CH 2 -, - CH 2 CH 2 CH 2 -, - CH (CH 3) CH 2 -, - CH (CH 2 CH 3) -, - _{C (CH 3) 2 -,} - CH 2 CH 2 CH 2 CH 2 -, - CH (CH 3) CH 2 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 -, - CH (CH 2 CH 2 CH 3) -, - C (CH 3) (CH 2 CH ₃ ) — and the like.

Y ³ is preferably a fluorinated alkylene group, and particularly preferably a fluorinated alkylene group in which the carbon atom bonded to the adjacent sulfur atom is fluorinated. Examples of such fluorinated alkylene _{group, -CF 2 -, - CF 2} CF 2 -, - CF 2 CF 2 CF 2 -, - CF (CF 3) CF 2 -, - CF 2 CF 2 CF 2 CF 2 _{-, - CF (CF 3)} CF 2 CF 2 -, - CF 2 CF (CF 3) CF 2 -, - CF (CF 3) CF (CF 3) -, - C (CF 3) 2 CF 2 -, _{-CF (CF 2 CF 3) CF} 2 -; - CH 2 CF 2 -, - CH 2 CH 2 CF 2 -, - CH 2 CF 2 CF 2 -; - CH 2 CH 2 CH 2 CF 2 -, - CH ₂ CH ₂ CF ₂ CF ₂ —, —CH ₂ CF ₂ CF ₂ CF ₂ — and the like can be mentioned.
Of _{these, -CF 2 -, - CF 2} CF 2 -, - CF 2 CF 2 CF 2 -, or _CH 2 _CF 2 CF ₂ - is _{preferable, -CF 2 -, - CF 2} CF 2 - or -CF ₂ CF ₂ CF ₂ - is more preferable, -CF ₂ - is particularly preferred.

The alkylene group or fluorinated alkylene group may have a substituent. An alkylene group or a fluorinated alkylene group has a “substituent” means that part or all of the hydrogen atom or fluorine atom in the alkylene group or fluorinated alkylene group is substituted with an atom or group other than a hydrogen atom and a fluorine atom. Means that
Examples of the substituent that the alkylene group or fluorinated alkylene group may have include an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a hydroxyl 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. It is preferable that all of R ⁵ ″ to R ⁶ ″ are 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, R 5 ^{"~R 6"} is most preferably all phenyl groups.
"The, ^{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. Trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate, tri (4-methylphenyl) sulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or the same 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) phenylsulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate; 1-phenyltetrahydrothiophenium trifluoromethane sulfonate, its heptafluoropropane sulfonate 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.

  Moreover, the onium salt which replaced the anion part of these onium salts by the anion represented by either of following formula (b1)-(b8) can also be used.

［式中、ｙは１〜３の整数であり、ｑ１〜ｑ２はそれぞれ独立に１〜５の整数であり、ｑ３は１〜１２の整数であり、ｔ３は１〜３の整数であり、ｒ１〜ｒ２はそれぞれ独立に０〜３の整数であり、ｉは１〜２０の整数であり、Ｒ^６’は置換基であり、ｍ１〜ｍ５はそれぞれ独立に０または１であり、ｖ１〜ｖ６はそれぞれ独立に０〜３の整数であり、ｗ１〜ｗ５はそれぞれ独立に０〜３の整数であり、Ｑ”は前記と同じである。］

[Wherein y is an integer of 1 to 3, q1 and q2 are each independently an integer of 1 to 5, q3 is an integer of 1 to 12, t3 is an integer of 1 to 3, and r1 -R2 is each independently an integer of 0-3, i is an integer of 1-20, R6 ^' is a substituent, m1 to m5 are each independently 0 or 1, and v1 to v6 are Each independently represents an integer of 0 to 3, w1 to w5 each independently represents an integer of 0 to 3, and Q ″ is the same as above.]

Examples of the substituent for R ^{6 ′} are the same as those described above as the substituent that the aliphatic hydrocarbon group may have and the substituent that the aromatic hydrocarbon group may have in X ⁵ . Things.
When the code | symbol (r1-r2, w1-w5) attached | subjected to R6 ^' is an integer greater than or equal to 2, several R6 ^' in the said compound may be the same respectively, and may differ.

  Moreover, the onium salt type acid generator which replaced the anion part by the anion represented by the following general formula (b-3) or (b-4) in the said general formula (b-1) or (b-2). (The cation moiety is the same as the cation moiety in (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 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 This is preferable because the transparency to the surface is improved.
The proportion 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 hydrogen atoms are substituted with fluorine atoms. A perfluoroalkylene group or a perfluoroalkyl group.

  Moreover, the sulfonium salt which has the cation represented by the following general formula (b-5) or (b-6) in a cation part 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 represented by the formula (b-5) or (b-6) in the cation part is not particularly limited, and the anion part of the onium salt acid generators proposed so far It may be similar.
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 represented by the above general formula (b-3) or (b-4), etc. Among them, a fluorinated alkyl sulfonate ion is preferable, and a fluorinated alkyl sulfonate ion having 1 to 4 carbon atoms. Are 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-. A 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 having no substituent or a fluorinated alkyl group having 1 to 4 carbon atoms.

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), alkyl or halogenated alkyl group having no substituent group for R ³³ preferably has 1 to 10 carbon atoms, 1 to 8 carbon atoms, more preferably, carbon 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 heteroaryl groups in which some of the carbon atoms constituting the ring of these groups are substituted with heteroatoms such as oxygen, sulfur and nitrogen atoms. 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 having no substituent as R ³⁵ described above.
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.
Further, an oxime sulfonate-based acid generator disclosed in JP-A-9-208554 (paragraphs [0012] to [0014] [chemical formula 18] to [chemical formula 19]), pamphlet of International Publication No. 04/074242, An oxime sulfonate-based acid generator disclosed in Examples 1 to 40) on pages 65 to 85 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, it is particularly preferable to use an onium salt having a fluorinated alkyl sulfonate ion as an anion as the component (B).
0.5-60 mass parts is preferable with respect to 100 mass parts of (A) component, and, as for content of (B) component in the positive resist composition of this invention, 1-40 mass parts is more preferable. 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.

<(D) component>
The positive resist composition of the present invention preferably further contains a nitrogen-containing organic compound component (D) (hereinafter referred to as “component (D)”) as an optional component.
The component (D) is not particularly limited as long as it acts as an acid diffusion control agent, that is, a quencher that traps the acid generated from the component (B) by exposure, and a wide variety of components have already been proposed. Therefore, any known ones may be used, and cyclic amines and aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are preferred. 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-pentylamine, tri-n-hexylamine , 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 more preferable, and tri-n-octylamine 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.
In the present invention, it is preferable to use a trialkylamine having 5 to 10 carbon atoms as the component (D).
In the positive resist composition of the present invention, the component (D) is preferably used in the range of usually 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the component (A). By setting the content in the above range, the resist pattern shape, the stability over time, and the like are improved.

<Optional component>
[(E) component]
The positive resist composition of the present invention includes, as optional components, organic carboxylic acids, phosphorus oxoacids and derivatives thereof for the purpose of preventing sensitivity deterioration, improving the resist pattern shape, retention stability over time, etc. At least one compound (E) selected from the group consisting of (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 include phosphoric acid, phosphonic acid, and phosphinic acid. 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.
In the positive resist composition of the present invention, the component (E) is preferably used at a ratio of 0.01 to 5.0 parts by mass per 100 parts by mass of the component (A).

  The positive resist composition of 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, dissolution inhibitors, Plasticizers, stabilizers, colorants, antihalation agents, dyes, and the like can be added and contained as appropriate.

[(S) component]
The positive resist composition of the present invention can be produced by dissolving a material in an organic solvent (hereinafter 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; Monohydric alcohols; compounds having an ester bond, such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, dipropylene glycol monoacetate, monomethyl ether, monoethyl of the polyhydric alcohols or compound having the 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.
Of 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 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 1 -20% by mass, preferably 1.5-15% by mass.

By using the positive resist composition of the present invention, there is an effect that a resist pattern having a good shape and a small LWR can be formed with excellent sensitivity. The reason why such an effect can be obtained is assumed as follows.
In the present invention, the resin component (A1) has a structural unit (a0) containing a group represented by the general formula (a0-0-1). The group represented by the general formula (a0-0-1) is a so-called acetal type acid dissociable, dissolution inhibiting group. The structural unit (a0) is dissociated by the action of an acid generated from the component (B) because the group contains “—C (R ^{1 ′} ) (R ^{2 ′} ) —O—Y ¹ —R ³ ”. Therefore, the dissociation efficiency of the acid dissociable, dissolution inhibiting group is improved. Thereby, it is considered that the difference in solubility (dissolution contrast) between the unexposed area and the exposed area in the alkaline developer is larger than that of the conventional positive resist composition. It is also considered that high sensitivity is easily obtained.
Furthermore, the group represented by the general formula (a0-0-1) includes “—Y ¹ -R ³ ”, thereby having a bulky and bulky structure as compared with a conventional acetal type acid dissociable, dissolution inhibiting group. Therefore, it is considered that pattern collapse, film reduction, and the like are suppressed, and a resist pattern having a favorable shape is easily formed. As one of the factors for obtaining a good pattern shape, the structural unit (a0) has a cyclic group containing —SO ₂ —, which is a polar group, at the end of a relatively long side chain. Since the affinity with the developer is improved, it is presumed that the lithography properties such as LWR are improved.
Therefore, the positive resist composition of the present invention is suitable as an EB or EUV resist. It is also highly useful for KrF.

Moreover, in the positive resist composition of the present invention, an effect that generation of outgas can be suppressed is also obtained. Thereby, contamination of the exposure apparatus is also reduced. The reason why such an effect is obtained is that the group represented by the general formula (a0-0-1) contains “—Y ¹ -R ³ ”, so that it can be compared with a conventional acetal type acid dissociable, dissolution inhibiting group. And a bulky and bulky structure, it is considered that the acid dissociable, dissolution inhibiting group is difficult to vaporize after dissociation.

≪Resist pattern formation method≫
The resist pattern forming method according to the second aspect of the present invention includes a step of forming a resist film on a support using the positive resist composition of the present invention, a step of exposing the resist film, and the resist A step of alkali-developing the film to form a resist pattern.
The resist pattern forming method of the present invention can be performed, for example, as follows.
That is, first, the positive resist composition is applied onto a support with a spinner or the like, and pre-baked (post-apply bake (PAB)) for 40 to 120 seconds, preferably 60 to 90, under a temperature condition of 80 to 150 ° C. This is applied for 2 seconds, and then an electron beam (EB) is selectively drawn (exposed) through a desired mask pattern by an electron beam drawing machine or the like, and then subjected to PEB (post-exposure heating) at a temperature of 80 to 150 ° C. ) For 40 to 120 seconds, preferably 60 to 90 seconds. Subsequently, this is alkali-development-processed using alkaline developing solution, for example, 0.1-10 mass% tetramethylammonium hydroxide (TMAH) aqueous solution, Preferably, water rinse is carried out using a pure water, and it dries. In some cases, a baking treatment (post-baking) may be performed after the alkali development treatment. In this way, a resist pattern faithful to the mask pattern can be obtained.

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 an organic antireflection film (organic BARC).

The wavelength used for the exposure is not particularly limited, and ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray, etc. Can be done using radiation.
The positive resist composition of the present invention is more effective for KrF excimer laser, ArF excimer laser, EB or EUV, and particularly effective for EB or EUV.

The exposure of the resist film may be normal exposure (dry exposure) performed in an inert gas such as air or nitrogen, or may be immersion exposure.
In immersion exposure, at the time of exposure, a solvent (having a refractive index larger than the refractive index of air) is formed between a lens and a resist film on the wafer, which is conventionally filled with an inert gas such as air or nitrogen. Exposure is performed in a state filled with the immersion medium.
More specifically, the immersion exposure is a solvent (immersion medium) having a refractive index larger than the refractive index of air between the resist film obtained as described above and the lowermost lens of the exposure apparatus. And in that state, exposure can be performed through a desired mask pattern (immersion exposure).
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 exposed by the immersion exposure 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.).

≪Polymer compound≫
In the polymer compound according to the third aspect of the present invention, the structural unit (a5) represented by the general formula (a5-1) and at least a part of the hydrogen atoms in the hydroxyl group of the structural unit (a5) are And a structural unit (a0-5) substituted with a group represented by the general formula (a0-0-1 ′).

The structural unit (a5) and the structural unit (a0-5) are the structural unit (a5) and the structural unit (a0-5) in the description of the positive resist composition according to the first aspect of the present invention. The same.
The proportion of the structural unit (a5) in the polymer compound of the present invention is preferably 45 to 90 mol%, more preferably 50 to 85 mol%, based on the total of all structural units constituting the polymer compound. More preferably, it is 55-80 mol%. By setting it to be equal to or higher than the lower limit of the above range, moderate alkali solubility can be obtained when used in a resist composition. Moreover, sufficient dry etching resistance can be obtained. By setting it to be equal to or less than the upper limit value of the range, it is possible to balance with other structural units.
The proportion of the structural unit (a0) in the polymer compound of the present invention is preferably in the range of 5 to 60 mol%, and preferably 10 to 55 mol% with respect to the total of all the structural units constituting the polymer compound. Is more preferable, and 15-50 mol% is further more preferable. By setting it to be equal to or more than the lower limit of the above range, higher resolution can be obtained when used in a resist composition. In addition, a resist pattern having a better shape is formed. By setting it to be equal to or less than the upper limit value of the range, it is possible to balance with other structural units.

  The polymer compound of the present invention has a structural unit (a5) and a structural unit (a0-5) among the components (A1) in the description of the positive resist composition according to the first aspect of the present invention. The same thing as a copolymer is mentioned.

The polymer compound of the present invention can be synthesized, for example, by reacting polyhydroxystyrene with a vinyl ether compound containing a “—Y ¹ -R ³ ” structure by a known method in the presence of an acid catalyst.
The structure of the obtained polymer compound is as follows: ¹ H-nuclear magnetic resonance (NMR) spectrum method, ¹³ C-NMR spectrum method, ¹⁹ F-NMR spectrum method, infrared absorption (IR) spectrum method, mass spectrometry (MS) method. It can be confirmed by general organic analysis methods such as elemental analysis and X-ray crystal diffraction.

The compound according to the fourth aspect of the present invention is represented by the general formula (a0-0-01).
The description of the compound of the present invention is the same as the description of the component (A1) of the positive resist composition of the present invention.

The compound of the present invention can be prepared, for example, by reacting an alcohol compound “R ³ —Y ¹ —OH” containing a “R ³ —Y ¹ —” structure with 1-bromo-2-chloroethane under a strong base, followed by potassium butoxide. It can synthesize | combine by the method of making it react.
The structure of the obtained polymer compound is as follows: ¹ H-nuclear magnetic resonance (NMR) spectrum method, ¹³ C-NMR spectrum method, ¹⁹ F-NMR spectrum method, infrared absorption (IR) spectrum method, mass spectrometry (MS) method. It can be confirmed by general organic analysis methods such as elemental analysis and X-ray crystal diffraction.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.
In this example, the unit represented by the chemical formula (1) is referred to as “compound 1”, and the same applies to compounds represented by other formulas.

[Reference Synthesis Example 1: Synthesis of Resin (A3-1)]
Under a nitrogen atmosphere, PGMEA was placed in a flask equipped with a nitrogen inlet, a stirrer, a condenser and a thermometer, and the temperature of the hot water bath was raised to 80 ° C. while stirring. Next, a monomer PGMEA solution charged with 2,2′-azobisisobutyronitrile (AIBN) and monomer (1) / monomer (2) = 2/1 (molar ratio) as a polymerization initiator was prepared. Using a dropping device, the solution was dropped into the flask at a constant rate over 6 hours, and then kept at 80 ° C. for 1 hour. Thereafter, the reaction solution was returned to room temperature. Subsequently, the obtained reaction solution was added dropwise to about 30 times amount of methanol with stirring to obtain a colorless precipitate. The resulting precipitate was filtered off, and the precipitate was washed in about 30 times the amount of methanol used for the monomer used for the polymerization. Then, this precipitate was filtered off and dissolved in THF, and then an 80% by mass hydrazine aqueous solution was added dropwise to the solution, followed by stirring at 25 ° C. for 1 hour. After completion of the reaction, the mixture was dropped into a large amount of water to obtain a precipitate. The precipitate was separated by filtration, washed, and dried under reduced pressure at 50 ° C. for about 40 hours to obtain a resin (A3-1).

The structure of the resin (A3-1) is shown below.
For the resin (A3-1), the standard polystyrene equivalent weight average molecular weight (Mw) determined by gel permeation chromatography (GPC) measurement was 10,000, and the dispersity (Mw / Mn) was 1.8. It was.
The composition ratio was calculated by carbon NMR. In the chemical formula, the symbol attached to the lower right of the structural unit indicates the ratio (mol%) of each structural unit in the copolymer.

[Reference Synthesis Example 2: Synthesis of Resin (A3-2)]
Resin (A3-2) was obtained by reacting poly (p-hydroxystyrene) and adamantyl vinyl ether in the presence of an acid catalyst by a known method.
The structure of resin (A3-2) is shown below.
As for the acetal introduction rate of this resin (A3-2), as a result of analysis by ¹ H-NMR, the acetal type acid dissociation represented by the above formula (VII-a-1) with respect to the number of hydroxyl groups of p-hydroxystyrene The ratio of the number of soluble dissolution inhibiting groups was 30%. From this, it was recognized that the acetal introduction ratio (hydroxyl protection ratio) was 30 mol%.
Moreover, about the resin (A3-2), the mass mean molecular weight (Mw) of standard polystyrene conversion calculated | required by GPC measurement was 10000, and dispersion degree (Mw / Mn) was 1.3.
In the following chemical formula, the symbol attached to the lower right of the structural unit indicates the ratio (mol%) of each structural unit in the copolymer.

[Synthesis Example 1: Synthesis of Compound 2]
Under a nitrogen atmosphere, Compound A (50.00 g) and dehydrated THF (50.00 g) were added to a three-necked flask and cooled to 5 ° C. or lower. NaH (6.38 g) was added thereto, and the mixture was stirred at 5 ° C. or lower for 5 minutes, and then 1-bromo-2-chloroethane (37.77 g) was fed. Thereafter, the mixture was stirred at 5 ° C. or lower for 10 minutes, gradually warmed up, and stirred at room temperature for 18 hours. The reaction solution was washed with 37 g of pure water three times. Subsequently, the reaction solution was concentrated and dried, and purified by column chromatography (silica gel) to obtain 14.32 g of Compound B.

The obtained compound B was analyzed by NMR, and the result was as follows.
¹ H-NMR (DMSO-d6, 400 MHz): δ (ppm) = 4.34-4.56 (m, OCH ₂ , 2H), 3.59-3.81 (m, sultone + CH ₂ Cl, 3H), 3.44-3.47 (m, sultone, 1H), 2.37-2.38 (m, sultone, 1H), 2.11-2.21 (m, sultone, 2H), 1.86-1 .91 (m, sultone, 1H), 1.74-1.77 (m, sultone, 1H)
From the above results, it was confirmed that the obtained compound had a structure represented by the following chemical formula (Compound B).

  Under a nitrogen atmosphere, Compound B (14.00 g) and dehydrated diethyl ether (140.00 g) were added to a three-necked flask and cooled to 5 ° C. or lower. Potassium-t-butoxide (6.16 g) was added thereto in small portions at 5 ° C. or less over 1 hour. After stirring the reaction mixture for 30 minutes, the solid was filtered off. The filtrate was concentrated and dried, and purified by column chromatography (silica gel) to obtain 3.51 g of Compound 2.

The obtained compound 2 was analyzed by NMR and the results were as follows.
¹ H-NMR (DMSO-d6, 400 MHz): δ (ppm) = 6.42 (dd, vinyl, 1H), 4.55-4.59 (m, sultone, 2H), 4.24 (dd, vinyl) , 1H), 4.10 (dd, vinyl, 1H), 3.41-3.73 (m, sultone, 2H), 3.41-3.58 (m, sultone, 1H), 2.31-2 .41 (m, sultone, 1H), 2.01-2.13 (m, sultone, 1H), 1.74-1.89 (m, sultone, 1H), 1.61-1.64 (m, sultone, 1H).
From the above results, it was confirmed that the obtained compound had a structure represented by the following chemical formula (Compound 2).

Example 1
[Synthesis Example 1: Synthesis of Resin (A1-11-1)]
In a nitrogen atmosphere, Compound 1 (10.00 g) and 1,3-dioxolane (40.00 g) were added and dissolved in a three-necked flask. The solution was cooled to 15 ° C., 35 mass% hydrochloric acid (0.12 g) was added thereto, and then a 25 mass% dioxolane solution of compound 2 (6.38 g) was slowly added dropwise. Then, after reacting for 5 hours at 30 _℃, 1% NH 3 to (0.70 g) was added and stirred for 10 minutes at room temperature. The reaction solution was added dropwise to pure water (850 g), the obtained powder (polymer wet powder) was filtered, and then vacuum dried to obtain the target resin (A1-11-1) as 10. 12 g was obtained.
About the acetal introduction | transduction rate of this resin (A1-11-1), it calculated by the integral ratio of the methine proton of an acetal part, and an aromatic proton by analysis of < ¹ > H-NMR. As a result, the acetal introduction rate was 30.2 mol%.
Moreover, about the resin (A1-11-1), the mass average molecular weight (Mw) of standard polystyrene conversion calculated | required by GPC measurement was 10800, and dispersion degree (Mw / Mn) was 1.08.

The obtained resin (A1-11-1) was analyzed by NMR. The results were as follows.
¹ H-NMR (Acetone-d6, 400 MHz): δ (ppm) = 7.98 (br peak, OH), 6.65 (Br peak, ArH), 5.53 (br peak, acetal-methine), 3 90 (br peak, sultone), 3.60 (br peak, sultone), 3.43 (br peak, sultone), 1.11-2.47 (br peak sultone).
From the above results, it was confirmed that the obtained resin had a structure represented by the following chemical formula [resin (A1-11-1)].
In addition, the code | symbol attached | subjected to the lower right of the structural unit in chemical formula shows the ratio (mol%) of each structural unit in a copolymer.

[Example 1, Comparative Examples 1-3]
Each component shown in Table 1 was mixed and dissolved to prepare a positive resist composition.

In Table 1, the numerical values in [] indicate the blending amount (parts by mass). Moreover, the symbol in Table 1 shows the following, respectively.
(A) -1: the resin (A1-11-1).
(A) -2: the resin (A3-1).
(A) -3: the resin (A3-2).
(B) -1: a compound represented by the following chemical formula (B) -1.
(B) -2: A compound represented by the following chemical formula (B) -2.
(D) -1: tri-n-octylamine.
(S) -1: PGMEA / PGME = 6/4 (mass ratio) mixed solvent.

The following evaluation was performed using the obtained resist composition.
<Evaluation of lithography characteristics-1>
Using the obtained positive resist composition, sensitivity, resist pattern shape, and LWR were evaluated.
[Resist pattern formation]
The positive resist composition of each example was applied to a coater (“Clean Track ACT-8”, manufactured by Tokyo Electron Ltd.) on an 8-inch silicon substrate subjected to hexamethyldisilazane (HMDS) treatment at 90 ° C. for 30 seconds. ) Was used to uniformly coat each of the films, and a baking process (PAB) was performed for 60 seconds at the temperatures shown in Table 2 to form a resist film (film thickness 60 nm).
The resist film is drawn (exposed) at an acceleration voltage of 70 keV using an electron beam lithography machine HL-800D (VSB) (manufactured by Hitachi), and baked at a temperature shown in Table 2 for 60 seconds (PEB). And developed for 60 seconds at 23 ° C. using a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH) (trade name: NMD-3, manufactured by Tokyo Ohka Kogyo Co., Ltd.). Thereafter, rinsing was performed with pure water for 15 seconds to form a line and space (L / S) pattern.

[Evaluation of sensitivity]
In the resist pattern formation, the optimum exposure dose Eop (μC / cm ² ) for forming an L / S pattern having a line width of 100 nm and a pitch of 200 nm was determined.
The results are shown in Table 2.

[Evaluation of resist pattern shape]
The L / S pattern having a line width of 100 nm and a pitch of 200 nm formed in the above Eop was observed using a scanning electron microscope (SEM), and the cross-sectional shape and the shape viewed from directly above were determined according to the following criteria. It was evaluated with.
The results are shown in Table 2.

(Criteria)
(Double-circle): It is a favorable shape without skirting and the rectangularity of the cross-sectional shape of a resist pattern is also high.
○: Good shape without skirting, but rectangularity is slightly low.
(Triangle | delta): The top part of the cross-sectional shape of a resist pattern is tinged, skirting is also seen, and rectangularity is low.

[Evaluation of LWR]
The line width of each L / S pattern formed by the resist pattern formation was measured at five locations in the longitudinal direction of the line with a length measurement SEM (scanning electron microscope, trade name: S-9220, manufactured by Hitachi, Ltd.) From the results, a triple value (3 s) of the standard deviation (s) was calculated as a scale (nm) indicating LWR.
The smaller the value of 3s, the smaller the roughness of the line width, which means that a more uniform width L / S pattern was obtained.
The results are shown in Table 2.

  As shown in Table 2, it can be confirmed that the resist composition of Example 1 according to the present invention is superior in sensitivity, LWR, and resist pattern shape as compared with the resist compositions of Comparative Examples 1 to 3. It was.

Claims (11)

A positive resist composition comprising a base component (A) whose solubility in an alkaline developer is increased by the action of an acid, and an acid generator component (B) that generates an acid upon exposure,
The base material component (A) includes a polymer compound (A1) having a structural unit (a0) containing an acid dissociable dissolution inhibiting group, and the acid dissociable dissolution inhibiting group in the structural unit (a0) is A positive resist composition comprising a group represented by general formula (a0-0-1).

[In formula (a0-0-1), R ¹ ′ and R ² ′ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Y ¹ is a single bond or a divalent linking group. , R ³ is a cyclic group containing —SO ₂ — in the ring skeleton. ] The positive resist composition according to claim 1, wherein R ³ in the formula (a0-0-1) is a cyclic group containing —O—SO ₂ — in the ring skeleton. The positive resist composition according to claim 2, wherein R ³ is represented by the following general formula (3-1).

[In Formula (3-1), a is an integer of 0 to 2, R ⁶ is an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyl group, —COOR ″, —OC (═O) R ″, hydroxyalkyl. A group or a cyano group, R ″ is a hydrogen atom or an alkyl group, and A ′ is an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, an oxygen atom or a sulfur atom. ]   The formula (a0-0-1) is a substituent of a hydrogen atom in a phenolic hydroxyl group (-OH), a carboxy group (-COOH), or a thiol group (-SH). 4. The positive resist composition according to any one of 3 above. The positive resist composition according to claim 1, wherein the structural unit (a0) is a structural unit (a0) represented by the following general formula (a0-1). .

[In the formula (a0-1), R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms; Y ⁰¹ is a divalent aromatic group; Y ⁰² Is —O—, —C (═O) O—, or —S—; R ¹ ′ and R ² ′ each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Y ¹ Is a single bond or a divalent linking group, a is an integer of 0 to 2, R ⁶ is an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyl group, —COOR ″, —OC (═O) R ″. , A hydroxyalkyl group or a cyano group, R ″ is a hydrogen atom or an alkyl group, and A ′ is an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, an oxygen atom or a sulfur atom. Is.]   The proportion of the structural unit (a0) in the resin component (A1) is in the range of 5 to 60 mol% with respect to the total of all the structural units constituting the resin component (A1). The positive resist composition as described in any one of the above. When the resin component (A1) is a structural unit (a5) represented by the following general formula (a5-1) and at least part of hydrogen atoms in the hydroxyl group of the structural unit (a5), the general formula (a0-0) The positive resist composition as described in any one of Claims 1-6 which has a structural unit (a0-5) substituted by group represented by -1).

[In Formula (a5-1), R ¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, and R ² is a halogen atom, an alkyl having 1 to 5 carbon atoms. A group or a halogenated alkyl group having 1 to 5 carbon atoms; p is an integer of 1 to 3, and q is an integer of 0 to 4. However, p + q is 1 or more and 5 or less. ]   Furthermore, the positive resist composition as described in any one of Claims 1-7 containing a nitrogen-containing organic compound component (D).   A step of forming a resist film on the support using the positive resist composition according to any one of claims 1 to 8, a step of exposing the resist film, and an alkali development of the resist film A resist pattern forming method including a step of forming a resist pattern. The structural unit (a5) represented by the following general formula (a5-1) and at least part of the hydrogen atoms in the hydroxyl group of the structural unit (a5) are represented by the following general formula (a0-0-1 ′). A polymer compound having a structural unit (a0-5) substituted with a group.

[In Formula (a5-1), R ¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, and R ² is a halogen atom, an alkyl having 1 to 5 carbon atoms. A group or a halogenated alkyl group having 1 to 5 carbon atoms; p is an integer of 1 to 3, and q is an integer of 0 to 4. However, p + q is 1 or more and 5 or less. ]

[In formula (a0-0-1 ′), R ¹ ′ and R ² ′ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Y ¹ represents a single bond or a divalent linking group. A is an integer of 0 to 2, R ⁶ is an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyl group, —COOR ″, —OC (═O) R ″, a hydroxyalkyl group or a cyano group, R ″ is a hydrogen atom or an alkyl group, and A ′ is an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, an oxygen atom or a sulfur atom.] The compound represented by the following general formula (a0-0-01).

[In Formula (a0-0-01), Y ¹ is a single bond or a divalent linking group, a is an integer of 0 to 2, and R ⁶ is an alkyl group, an alkoxy group, a halogenated alkyl group, or a hydroxyl group. , —COOR ″, —OC (═O) R ″, a hydroxyalkyl group or a cyano group, R ″ is a hydrogen atom or an alkyl group, and A ′ is a carbon number that may contain an oxygen atom or a sulfur atom. 1 to 5 alkylene groups, oxygen atoms, or sulfur atoms.]