JP2007231202A - Copolymer and radiation sensitive resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation sensitive resin composition excellent in solubility in alkaline developing liquid and excellent in etching resistance, and a copolymer capable of being used for the radiation sensitive resin composition. <P>SOLUTION: This copolymer is provided by containing a recurring unit expressed by formula (1) and a recurring unit having an acid dissociative group, and becoming an easily alkaline soluble by the action of an acid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an acrylic polymer and a radiation-sensitive resin composition, and in particular, various radiations such as deep ultraviolet rays such as KrF excimer laser or ArF excimer laser, X-rays such as synchrotron radiation, and charged particle beams such as electron beams. The present invention relates to a radiation-sensitive resin composition that can be suitably used as a chemically amplified resist useful for microfabrication using the above and a copolymer that can be used in the composition.

In the field of microfabrication typified by the manufacture of integrated circuit elements, in order to obtain a higher degree of integration, recently, an ArF excimer laser (wavelength 193 nm), an F ₂ excimer laser (wavelength 157 nm) or the like is used. There is a need for a lithography technique capable of microfabrication at the same level. As a radiation-sensitive resin composition suitable for irradiation with such an excimer laser, a chemistry utilizing the chemical amplification effect of a component having an acid dissociable functional group and an acid generator that is a component that generates an acid upon irradiation with radiation. Many amplified radiation-sensitive compositions have been proposed. For example, as a resin component, a polymer compound for a photoresist having a specific structure including a monomer unit having a norbornane ring derivative as a resin component is known (Patent Documents 1 and 2).
In addition, a resist composition using a (meth) acrylic acid copolymer having an ester of narrowly dispersible (meth) acrylic acid and a specific monocyclohexane or bicycloheptanecarbolactone as a repeating unit is known ( Patent Document 3).
In addition, a repeating unit having a lactone ring in the side chain, a repeating unit having a polycyclic alicyclic hydrocarbon group containing only carbon and hydrogen not containing a polar group in the side chain, and an acid dissociable group in the side chain Pattern line edge roughness after development as a chemically amplified resist sensitive to far ultraviolet rays represented by an ArF excimer laser (wavelength 193 nm) using a radiation-sensitive resin composition containing an acrylic polymer containing repeating units It is known that the heat treatment dependency after irradiation can be reduced (Patent Document 4).
JP 2002-201232 A JP 2002-145955 A JP 2003-84436 A JP-A-2005-68418

  However, in the semiconductor field, when a higher degree of integration is required, the radiation-sensitive resin composition that is a resist is required to have a higher resolution. At the same time, as miniaturization progresses, many cases have been seen in which minute defects generated during development become fatal defects in device design. In order to cope with such a situation, there is an urgent need to achieve both the excellent etching resistance as a resist and the property of being excellent in solubility in a developer after exposure. Further, along with miniaturization, excellent etching resistance is required.

  The present invention has been made in order to address the above-described problems. By using a copolymer having a specific structure and this copolymer, the transparency to radiation is high, and sensitivity, resolution, dry etching resistance, pattern Radiation-sensitive resin composition excellent in basic physical properties as a resist such as shape, in particular, excellent solubility in an alkaline developer and etching resistance, and a copolymer that can be used for this radiation-sensitive resin composition The purpose is to provide.

（Ｒ¹は水素原子、炭素数が１〜４のアルキル基またはトリフルオロメチル基、Ｘは単結合または２価の有機基を表し、Ｙは水素原子または下記式（２）で表される基を表し、少なくとも１つのＹは式（２）で表され、

Ｒ²は２価の有機基を表し、Ｒ³は炭素数１〜６の直鎖状もしくは分岐状のアルキル基、炭素数３〜６の脂環式炭化水素基、またはフェニル基を表す。） The copolymer of the present invention contains the repeating unit (i) represented by the formula (1) and the repeating unit (ii) having an acid dissociable group, and is insoluble in alkali or hardly soluble in alkali, A polystyrene-reduced weight average molecular weight by gel permeation chromatography that becomes readily soluble in alkali by action is 1,000 to 200,000.

(R ¹ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a trifluoromethyl group, X represents a single bond or a divalent organic group, Y represents a hydrogen atom or a group represented by the following formula (2) Wherein at least one Y is represented by formula (2),

R ² represents a divalent organic group, and R ³ represents a linear or branched alkyl group having 1 to 6 carbon atoms, an alicyclic hydrocarbon group having 3 to 6 carbon atoms, or a phenyl group. )

（Ｒ⁴は水素原子、炭素数が１〜４のアルキル基またはトリフルオロメチル基を表し、Ｒ⁵は相互に独立に炭素数４〜２０の１価の脂環式炭化水素基もしくはその誘導体または炭素数１〜４の直鎖状もしくは分岐状のアルキル基を表し、かつＲ⁵の少なくとも１つが該脂環式炭化水素基もしくはその誘導体であるか、あるいは何れか２つのＲ⁵が相互に結合して、それぞれが結合している炭素原子とともに炭素数４〜２０の２価の脂環式炭化水素基もしくはその誘導体を形成し、残りのＲ⁵が炭素数１〜４の直鎖状もしくは分岐状のアルキル基または炭素数４〜２０の１価の脂環式炭化水素基もしくはその誘導体を表す。）
本発明の感放射線性樹脂組成物は、アルカリ不溶性またはアルカリ難溶性であって、酸の作用によりアルカリ易溶性になる上記共重合体を樹脂成分とし、感放射線性酸発生剤を含有することを特徴とする。 The repeating unit (ii) having an acid dissociable group constituting the copolymer is represented by the following formula (3).

(R ⁴ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a trifluoromethyl group, and R ⁵ is independently a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or Represents a linear or branched alkyl group having 1 to 4 carbon atoms, and at least one of R ⁵ is the alicyclic hydrocarbon group or a derivative thereof, or any two R ⁵ are bonded to each other Then, a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof is formed together with the carbon atoms to which each is bonded, and the remaining R ⁵ is linear or branched having 1 to 4 carbon atoms. An alkyl group in the form of a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof.
The radiation-sensitive resin composition of the present invention contains a radiation-sensitive acid generator containing, as a resin component, the above copolymer that is insoluble in alkali or hardly soluble in alkali and easily soluble in alkali by the action of an acid. Features.

  Since the copolymer of the present invention contains the repeating unit (i) represented by the formula (1), it has an adamantane skeleton in the side chain and an ester structure at a site away from the main chain. Therefore, the radiation-sensitive resin composition containing the copolymer of the present invention as a resin component has etching resistance based on an adamantane skeleton and is excellent in solubility in a developer after exposure based on an ester structure.

Hereinafter, embodiments of the present invention will be described in detail.
Examples of the alkyl group having 1 to 4 carbon atoms represented by R ¹ in the formula (1) include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, and an n-butyl group. Preferred R ¹ is a hydrogen atom or a methyl group.
Examples of the divalent organic group represented by X include an alkylene group having 1 to 6 carbon atoms, an oxyalkylene group, and a partially or completely fluorinated alkylene group. Preferred X is a single bond or an oxyalkylene group. Further preferred X is a single bond or an oxyethylene group.
Y represents a hydrogen atom or a group represented by formula (2), and at least one Y is represented by formula (2).
The divalent organic group represented by R ² in the formula (2) may be linear or branched, and examples thereof include an alkylene group having 1 to 6 carbon atoms, partially or completely Examples include fluorinated alkylene groups. Preferred R ² is a single bond or a methylene group, an ethylene group or a methylethylene group.
Examples of the linear or branched alkyl group having 1 to 6 carbon atoms represented by R ³ in the formula (2) include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, Examples include t-butyl group, n-pentyl group, n-hexyl group and the like. Moreover, as a C3-C6 alicyclic hydrocarbon group, a cyclopentyl group and a cyclohexyl group are mentioned. Preferred R ³ is a methyl group or an ethyl group.

式（１ａ）において、Ｒ¹、ＸおよびＹは式（１）のそれと同一である。
本発明において好ましい繰り返し単位（ｉ）を生成する式（１ａ）で表される単量体を以下に挙げる。
３−［２−メトキシ−２−オキソエトキシ］アダマンチル （メタ）アクリレート、３−［２−エトキシ−２−オキソエトキシ］アダマンチル （メタ）アクリレート、３−［２−プロポキシ−２−オキソエトキシ］アダマンチル （メタ）アクリレート、３−［２−メトキシ−１−メチル−２−オキソエトキシ］アダマンチル （メタ）アクリレート、３−［２−エトキシ−１−メチル−２−オキソエトキシ］アダマンチル （メタ）アクリレート、３−［２−プロポキシ−１−メチル−２−オキソエトキシ］アダマンチル （メタ）アクリレート、３−［２−メトキシ−１−エチル−２−オキソエトキシ］アダマンチル （メタ）アクリレート、３−［２−エトキシ−１−エチル−２−オキソエトキシ］アダマンチル （メタ）アクリレート、３−［２−プロポキシ−１−エチル−２−オキソエトキシ］アダマンチル （メタ）アクリレート、３−［３−メトキシ−３−オキソプロポキシ］アダマンチル （メタ）アクリレート、３−［３−エトキシ−３−オキソプロポキシ］アダマンチル （メタ）アクリレート、３−［４−メトキシ−４−オキソブトキシ］アダマンチル （メタ）アクリレート、３−［４−エトキシ−４−オキソブトキシ］アダマンチル （メタ）アクリレート、３−［２−シクロヘキシルオキシ−２−オキソエトキシ］アダマンチル （メタ）アクリレート、３−［２−シクロヘキシルオキシ−１−メチル−２−オキソエトキシ］アダマンチル （メタ）アクリレート、３，５−ビス［２−メトキシ−２−オキソエトキシ］アダマンチル （メタ）アクリレート、３，５−ビス［２−エトキシ−２−オキソエトキシ］アダマンチル （メタ）アクリレートを例示できる。 The repeating unit (i) represented by the formula (1) can be obtained by polymerizing a monomer represented by the following formula (1a).

In the formula (1a), R ¹ , X and Y are the same as those in the formula (1).
Examples of the monomer represented by the formula (1a) that generates the preferred repeating unit (i) in the present invention are listed below.
3- [2-methoxy-2-oxoethoxy] adamantyl (meth) acrylate, 3- [2-ethoxy-2-oxoethoxy] adamantyl (meth) acrylate, 3- [2-propoxy-2-oxoethoxy] adamantyl ( (Meth) acrylate, 3- [2-methoxy-1-methyl-2-oxoethoxy] adamantyl (meth) acrylate, 3- [2-ethoxy-1-methyl-2-oxoethoxy] adamantyl (meth) acrylate, 3- [2-propoxy-1-methyl-2-oxoethoxy] adamantyl (meth) acrylate, 3- [2-methoxy-1-ethyl-2-oxoethoxy] adamantyl (meth) acrylate, 3- [2-ethoxy-1 -Ethyl-2-oxoethoxy] adamantyl (meth) acrylate, 3- 2-propoxy-1-ethyl-2-oxoethoxy] adamantyl (meth) acrylate, 3- [3-methoxy-3-oxopropoxy] adamantyl (meth) acrylate, 3- [3-ethoxy-3-oxopropoxy] adamantyl (Meth) acrylate, 3- [4-methoxy-4-oxobutoxy] adamantyl (meth) acrylate, 3- [4-ethoxy-4-oxobutoxy] adamantyl (meth) acrylate, 3- [2-cyclohexyloxy-2 -Oxoethoxy] adamantyl (meth) acrylate, 3- [2-cyclohexyloxy-1-methyl-2-oxoethoxy] adamantyl (meth) acrylate, 3,5-bis [2-methoxy-2-oxoethoxy] adamantyl ( (Meth) acrylate, 3,5-bis 2-ethoxy-2-oxo-ethoxy] adamantyl (meth) acrylate can be exemplified.

Ｒ⁴は水素原子、炭素数が１〜４のアルキル基またはトリフルオロメチル基を表し、Ｒ⁵は相互に独立に炭素数４〜２０の１価の脂環式炭化水素基もしくはその誘導体または炭素数１〜４の直鎖状もしくは分岐状のアルキル基を表し、かつＲ⁵の少なくとも１つが該脂環式炭化水素基もしくはその誘導体であるか、あるいは何れか２つのＲ⁵が相互に結合して、それぞれが結合している炭素原子とともに炭素数４〜２０の２価の脂環式炭化水素基もしくはその誘導体を形成し、残りのＲ⁵が炭素数１〜４の直鎖状もしくは分岐状のアルキル基または炭素数４〜２０の１価の脂環式炭化水素基もしくはその誘導体を表す。
Ｒ⁴における炭素数が１〜４のアルキル基としては、Ｒ¹で例示した炭素数が１〜４のアルキル基を挙げることができる。 The repeating unit (ii) having an acid dissociable group in the copolymer is a repeating unit obtained by polymerizing a monomer represented by the following formula (3a).

R ⁴ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a trifluoromethyl group, and R ⁵ is independently a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or carbon. Represents a linear or branched alkyl group of formulas 1 to 4, and at least one of R ⁵ is the alicyclic hydrocarbon group or a derivative thereof, or any two of R ⁵ are bonded to each other. A divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof together with the carbon atoms to which each is bonded, and the remaining R ⁵ is linear or branched having 1 to 4 carbon atoms. Or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof.
Examples of the alkyl group having 1 to 4 carbon atoms in R ⁴ include the alkyl groups having 1 to 4 carbon atoms exemplified in R ¹ .

A monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms of R ^{5 and} a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms formed by bonding any two R ⁵ to each other; Is, for example, a group consisting of an alicyclic ring derived from norbornane, tricyclodecane, tetracyclododecane, adamantane, cycloalkanes such as cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, etc .; these alicyclic rings A group consisting of an aromatic ring, for example, a carbon number such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, a 1-methylpropyl group, or a t-butyl group; Examples thereof include a group substituted with one or more of 1 to 4 linear, branched or cyclic alkyl groups. Of these alicyclic hydrocarbon groups, the groups consisting of alicyclic rings derived from norbornane, tricyclodecane, tetracyclododecane, adamantane, cyclopentane or cyclohexane, and groups consisting of these alicyclic rings are described above. A group substituted with an alkyl group is preferred.

  Examples of the alicyclic hydrocarbon group derivative include hydroxyl group; carboxyl group; oxo group (that is, ═O group); hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1- Hydroxypropyl groups having 1 to 4 carbon atoms such as hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group An alkoxyl group having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, a 2-methylpropoxy group, a 1-methylpropoxy group and a t-butoxy group; Group: C2-C5 such as cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, etc. A substituent such as Anoarukiru group can include one or more or one or more having groups. Of these substituents, a hydroxyl group, a carboxyl group, a hydroxymethyl group, a cyano group, a cyanomethyl group and the like are preferable.

Examples of the linear or branched alkyl group having 1 to 4 carbon atoms of R ⁵ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and 2-methylpropyl. Group, 1-methylpropyl group, t-butyl group and the like. Of these alkyl groups, a methyl group and an ethyl group are preferable.

上記各式において、各Ｒ⁶は相互に独立に炭素数１〜４の直鎖状もしくは分岐状のアルキル基を表し、ｍ'は０〜６である。炭素数１〜４の直鎖状もしくは分岐状のアルキル基としては、例えば、メチル基、エチル基、ｎ−プロピル基、ｉ−プロピル基、ｎ−ブチル基、２−メチルプロピル基、１−メチルプロピル基、ｔ−ブチル基等を挙げることができる。これらのアルキル基のうち、メチル基、エチル基が好ましい。
本発明において好ましい−Ｃ（Ｒ⁵）₃部分の骨格としては、１−アルキルシクロアルカン類であり、Ｒ⁶はメチル基またはエチル基である。 The -COOC (R ⁵⁾ -C in ₃ portions (R ⁵⁾ ₃ portion of the backbone of formula (3) or formula (3a), for example, the following formulas (3a-1), formula (3a-2), wherein And groups represented by (3a-3), formula (3a-4), formula (3a-5), or formula (3a-6).

In the above formulas, each R ⁶ independently represents a linear or branched alkyl group having 1 to 4 carbon atoms, and m ′ is 0 to 6. Examples of the linear or branched alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, and a 1-methyl group. A propyl group, a t-butyl group, etc. can be mentioned. Of these alkyl groups, a methyl group and an ethyl group are preferable.
In the present invention, preferred —C (R ⁵ ) ₃ moiety skeletons are 1-alkylcycloalkanes, and R ⁶ is a methyl group or an ethyl group.

In the formula (3) or the formula (3a), the —COOC (R ⁵ ) ₃ moiety is dissociated by the action of an acid to form a carboxyl group to be a readily alkali-soluble site. The “alkali-soluble site” is a group that becomes an anion by the action of an alkali (easily soluble in alkali). The “acid-dissociable group” refers to a group in which an alkali-soluble site is protected with a protective group, and a group that is not “alkali-soluble” until the protective group is removed with an acid. Say. By containing the repeating unit represented by the formula (3), the copolymer of the present invention becomes an alkali-soluble resin by the action of an acid from an alkali-insoluble or hardly-alkali-soluble resin. "Alkali insoluble or alkali poorly soluble" means that under the alkali development conditions employed when a resist pattern is formed from a resist film formed from a radiation-sensitive resin composition containing the copolymer of the present invention. When a film using only the copolymer of the present invention is developed instead of the resist film, it means the property that 50% or more of the initial film thickness of the film remains after development. “Alkali-soluble” means a property that a film is dissolved by the same treatment and 50% or more of the initial film thickness is lost.

式（４）または式（５）において、Ｒ⁷は水素原子、メチル基、またはトリフルオロメチル基を表し、Ｒ⁸は水素原子、炭素数１〜４の直鎖状もしくは分岐状のアルキル基、炭素数１〜４の直鎖状もしくは分岐状のアルコキシ基、または、炭素数１〜４の直鎖状もしくは分岐状のフッ素化アルキル基を表し、Ｚは炭素数７〜２０の炭素原子および水素原子のみからなる多環型脂環式炭化水素基を表す。 The copolymer of the present invention comprises a repeating unit (iii) represented by the following formula (4) together with a repeating unit (ii) represented by the formula (1) and a repeating unit (ii) represented by the formula (3). ) And / or a repeating unit (iv) represented by the following formula (5).

In Formula (4) or Formula (5), R ⁷ represents a hydrogen atom, a methyl group, or a trifluoromethyl group, R ⁸ represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, Represents a linear or branched alkoxy group having 1 to 4 carbon atoms or a linear or branched fluorinated alkyl group having 1 to 4 carbon atoms, Z is a carbon atom having 7 to 20 carbon atoms and hydrogen A polycyclic alicyclic hydrocarbon group consisting only of atoms is represented.

The repeating unit (iii) represented by the formula (4) has an alicyclic hydrocarbon group derived from 5-oxo-4-oxatricyclo [4.2.1.0 ^3,7 ] nonane as a lactone skeleton. Part of the side chain. The lactone skeleton may be substituted with a linear or branched alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a fluorinated alkyl group.
Examples of the linear or branched alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, and a 1-methyl group. Examples thereof include a propyl group and a t-butyl group. Examples of the linear or branched alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, and an n-butoxy group. , 2-methylpropoxy group, 1-methylpropoxy group, t-butoxy group and the like. Examples of the linear or branched fluorinated alkyl group having 1 to 4 carbon atoms include groups in which part or all of the hydrogen atoms in the alkyl group have been replaced with fluorine atoms.
Among the repeating units represented by the formula (4), a preferable repeating unit is an alicyclic hydrocarbon group derived from 5-oxo-4-oxatricyclo [4.2.1.0 ^3,7 ] nonane. Has in side chain.

これらのシクロアルカン由来の脂環族環は、置換基を有していてもよく、例えば、メチル基、エチル基、ｎ−プロピル基、ｉ−プロピル基、ｎ−ブチル基、２−メチルプロピル基、１−メチルプロピル基、ｔ−ブチル基等の炭素数１〜４の直鎖状、分岐状または環状のアルキル基の１種以上あるいは１個以上で置換した骨格等が挙げられる。 The repeating unit (iv) represented by the formula (5) has, as Z, a polycyclic alicyclic hydrocarbon group consisting of only a carbon atom having 7 to 20 carbon atoms and a hydrogen atom in a part of the side chain. Preferably, it has a polycyclic alicyclic hydrocarbon group consisting only of carbon atoms and hydrogen atoms not containing a polar group having 7 to 20 carbon atoms in a part of the side chain. Examples of such polycyclic alicyclic hydrocarbon groups include bicyclo [2.2.1] heptane (5a), bicyclo [2.2.2] octane (5b), as shown in the following formula: Tricyclo [5.2.1.0 ^2,6 ] decane (5c), tetracyclo [6.2.1.1 ^3,6 . And hydrocarbon groups composed of alicyclic rings derived from cycloalkanes such as 0 ^2,7 ] dodecane (5d) and tricyclo [3.3.1.1 ^3,7 ] decane (5e).

These cycloalkane-derived alicyclic rings may have a substituent, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group. , A skeleton substituted with one or more linear, branched or cyclic alkyl groups having 1 to 4 carbon atoms such as 1-methylpropyl group and t-butyl group.

The copolymer of the present invention preferably contains the repeating unit (i), the repeating unit (ii) and the repeating unit (iii). This copolymer is excellent in etching resistance and solubility in a developer after exposure. Moreover, when improving etching tolerance more, it is preferable that it is a copolymer containing a repeating unit (iv) in addition to these three repeating units.
As a monomer which produces each said repeating unit, corresponding (meth) acrylic acid derivative ester is mentioned, respectively. In addition, the description with (meth) acrylic acid represents acrylic acid or methacrylic acid.

  The proportion of each repeating unit in the copolymer of the present invention is such that the repeating unit (i) is 5 to 60 mol%, preferably 10 to 40 mol%, based on all repeating units constituting the copolymer; ii) is 10 to 70 mol%, preferably 30 to 60 mol%; repeating unit (iii) is 20 to 60 mol%, preferably 30 to 50 mol%; the content of repeating unit (i) is 5 mol% If it is less than 60%, the dry etching resistance tends to decrease, and if it exceeds 60 mol%, the resolution as a resist tends to decrease. If the content of the repeating unit (ii) is less than 10 mol%, the resolution tends to be lowered, and if it exceeds 70 mol%, the developability tends to be lowered. When the content of the repeating unit (iii) is less than 20 mol%, the developability tends to be lowered, and when it exceeds 60 mol%, the resolution is lowered and the solubility in the developer tends to be lowered.

The copolymer of the present invention uses, for example, a mixture of monomers corresponding to each repeating unit using a radical polymerization initiator such as hydroperoxides, dialkyl peroxides, diacyl peroxides, azo compounds, If necessary, it can be produced by polymerization in an appropriate solvent in the presence of a chain transfer agent.
Examples of the solvent used for the polymerization include cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane; ethyl acetate, n-butyl acetate, i-butyl acetate, methyl propionate, propylene glycol monomethyl ether. Saturated carboxylic acid esters such as acetate; alkyl lactones such as γ-butyrolactone; alkyl ketones such as 2-butanone, 2-heptanone and methyl isobutyl ketone; cycloalkyl ketones such as cyclohexanone; 2-propanol, propylene glycol monomethyl Examples include alcohols such as ether.
These solvents can be used alone or in admixture of two or more.
Moreover, the reaction temperature in the said superposition | polymerization is 40-120 degreeC normally, Preferably it is 50-100 degreeC, and reaction time is 1-48 hours normally, Preferably it is 1-24 hours.

The copolymer of the present invention is naturally low in impurities such as halogen and metal, and the residual monomer and oligomer components are preferably not more than predetermined values, for example, 0.1 wt% by HPLC, Thereby, not only can the sensitivity, resolution, process stability, pattern shape, and the like as a resist be further improved, but also a radiation-sensitive composition that can be used as a resist that does not change with time such as foreign matter in liquid or sensitivity.
Examples of the method for purifying the copolymer include the following methods. As a method of removing impurities such as metals, the metal is chelated and removed by adsorbing the metal in the resin solution using a zeta potential filter or by washing the resin solution with an acidic aqueous solution such as oxalic acid or sulfonic acid. And the like. In addition, as a method of removing residual monomer and oligomer components below the specified value, liquid-liquid extraction method that removes residual monomer and oligomer components by combining water washing and an appropriate solvent, those with a specific molecular weight or less Refining method in the state of solution such as ultrafiltration that only extracts and removes residual monomers by coagulating the polymer in the poor solvent by dropping the copolymer solution into the poor solvent There are solid state purification methods such as precipitation and washing the filtered polymer slurry with a poor solvent. Moreover, these methods can also be combined. The poor solvent used in the reprecipitation method depends on the physical properties of the copolymer to be purified and cannot be generally exemplified. As appropriate, the poor solvent is selected.

The polystyrene-reduced weight average molecular weight (hereinafter abbreviated as “Mw”) by gel permeation chromatography (GPC) of the copolymer is usually 1,000 to 200,000, preferably 2,000 to 50,000, Preferably it is 3,000-30,000. In this case, when the Mw of the copolymer is less than 1,000, the heat resistance as a resist tends to decrease, and when it exceeds 200,000, the developability as a resist tends to decrease.
The ratio (Mw / Mn) of the copolymer Mw to the polystyrene-equivalent number average molecular weight (hereinafter abbreviated as “Mn”) by gel permeation chromatography (GPC) is usually 1-7.
In addition, Mw and Mn are Tosoh Co., Ltd. high-speed GPC apparatus (model "HLC-8120"), Tosoh Co., Ltd. GPC column (brand name "G2000H _XL "; two, "G3000H _XL "; one , “G4000H _XL ”: 1), measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under the analysis conditions of a flow rate of 1.0 ml / min, elution solvent tetrahydrofuran, and column temperature of 40 ° C. did.

In this invention, a copolymer can be used individually or in mixture of 2 or more types.
The copolymer is insoluble in alkali or hardly soluble in alkali, but becomes easily soluble in alkali by the action of an acid. Therefore, it is suitable as an acid-dissociable group-containing resin used for the radiation-sensitive resin composition.

A radiation-sensitive resin composition is obtained by using the copolymer as an acid-dissociable group-containing resin and combining with an acid generator that is a component that generates an acid upon irradiation with radiation.
Examples of the acid generator include onium salts such as sulfonium salts and iodonium salts, organic halogen compounds, and sulfone compounds such as disulfones and diazomethane sulfones.
Preferred examples of the acid generator include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1]. ] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 2- (3-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecanyl) -1 , 1-difluoroethanesulfonate, triphenylsulfonium N, N′-bis (nonafluoro-n-butanesulfonyl) imidate, triphenylsulfonium salt compounds such as triphenylsulfonium camphorsulfonate;

4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2. 2.1] Hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2- (3-tetracyclo [4.4.0.1 ^2,5 .1 ^{7, 10} ] dodecanyl) -1,1-difluoroethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium N, N′-bis (nonafluoro-n-butanesulfonyl) imidate, 4-cyclo 4-cyclohexylphenyldiphenylsulfonium salt compounds such as hexylphenyldiphenylsulfonium camphorsulfonate;

4-t-butylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-t-butylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-t-butylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-t-butylphenyl Diphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-t-butylphenyldiphenylsulfonium 2- (3-tetracyclo [4.4. 0.1 ^2,5 .1 ^7,10 ] dodecanyl) -1,1-difluoroethanesulfonate, 4-t-butylphenyldiphenylsulfonium N, N′-bis (nonafluoro-n-butanesulfonyl) imidate, 4-t- Butylphenyl diphenyls 4-t-butylphenyldiphenylsulfonium salt compounds such as rufonium camphorsulfonate;

Tri (4-t-butylphenyl) sulfonium trifluoromethanesulfonate, tri (4-t-butylphenyl) sulfonium nonafluoro-n-butanesulfonate, tri (4-t-butylphenyl) sulfonium perfluoro-n-octanesulfonate, Tri (4-t-butylphenyl) sulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, tri (4-t-butylphenyl) sulfonium 2 - (3-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecanyl) -1,1-difluoroethanesulfonate, tri (4-t- butylphenyl) sulfonium N, N'-bis (nonafluoro -N-butanesulfonyl) imidate, tri (4-t-butylphenyl) sulfonium can Tri (4-t-butylphenyl) sulfonium salt compounds such as fursulfonate;

Diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2, 2-tetrafluoroethane sulfonate, diphenyliodonium 2- (3-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecanyl) -1,1-difluoroethanesulfonate, diphenyliodonium N, N'-bis Diphenyliodonium salt compounds such as (nonafluoro-n-butanesulfonyl) imidate, diphenyliodonium camphorsulfonate;

Bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, Bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t-butylphenyl) iodonium 2 - (3-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecanyl) -1,1-difluoroethanesulfonate, bis (4-t- butylphenyl) iodonium N, N'-bis (nonafluoro -N-butanesulfonyl) imidate, bis (4-t-butylphenyl) iodonium can Bis (4-tert-butylphenyl) iodonium salt compounds such as fursulfonate;

1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, (4-n-Butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium 2-bicyclo [2.2. 1] Hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium 2- (3-tetracyclo [4.4. 0.1 ^2,5 .1 ^7,10] dodecanyl) -1,1-difluoroethanesulfonate, 1- (4- -Butoxynaphthalen-1-yl) tetrahydrothiophenium N, N′-bis (nonafluoro-n-butanesulfonyl) imidate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphorsulfonate, etc. 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium salt compound;

1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, (3,5-Dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2. 1] Hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium 2- (3-tetracyclo [4.4. 0.1 ^2,5 .1 ^7,10] dodecanyl) -1,1-difluoroethanesulfinate 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium N, N′-bis (nonafluoro-n-butanesulfonyl) imidate, 1- (3,5-dimethyl-4-hydroxyphenyl) 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium salt compounds such as tetrahydrothiophenium camphorsulfonate;

N- (trifluoromethanesulfonyloxy) succinimide, N- (nonafluoro-n-butanesulfonyloxy) succinimide, N- (perfluoro-n-octanesulfonyloxy) succinimide, N- (2-bicyclo [2.2.1] Hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) succinimide, N- (2- (3-tetracyclo [4.4.0.1 ^2,5 .1, ^7,10 ] dodecanyl) Succinimide compounds such as -1,1-difluoroethanesulfonyloxy) succinimide and N- (camphorsulfonyloxy) succinimide;

N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy) bicyclo [2.2.1] hept -5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- ( 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboxy imide, N- (2- (3- tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecanyl) -1,1-difluoroethane-sulfonyloxy) bicyclo [2.2.1] hept -5 -En Bicyclo [2.2.1] hept-5, such as 2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide Examples include ene-2,3-dicarboximide compounds.

  In this invention, an acid generator can be used individually or in mixture of 2 or more types. The amount of the acid generator used is usually 0.1 to 30 parts by weight, preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the copolymer, from the viewpoint of ensuring sensitivity and developability as a resist. It is. In this case, if the amount of the acid generator used is less than 0.1 parts by weight, the sensitivity and developability tend to decrease. On the other hand, if it exceeds 30 parts by weight, the transparency to the radiation decreases, and a rectangular resist pattern. Tends to be difficult to obtain.

In the radiation sensitive resin composition of the present invention, an acid diffusion controller, an alicyclic additive having an acid dissociable group, an alicyclic additive not having an acid dissociable group, and a surfactant are included as necessary. Various additives such as a sensitizer can be blended.
The acid diffusion controller is a component having an action of controlling a diffusion phenomenon of an acid generated from an acid generator upon irradiation in a resist film and suppressing an undesirable chemical reaction in a non-irradiated region.
By blending such an acid diffusion control agent, the storage stability of the resulting radiation-sensitive resin composition is improved, the resolution as a resist is further improved, and the holding time from irradiation to development processing ( The change in the line width of the resist pattern due to the variation in PED) can be suppressed, and a composition having excellent process stability can be obtained.
The acid diffusion controller is preferably a nitrogen-containing organic compound whose basicity does not change by irradiation or heat treatment during the resist pattern formation step.

Examples of such nitrogen-containing organic compounds include “tertiary amine compounds”, “amide group-containing compounds”, “quaternary ammonium hydroxide compounds”, “nitrogen-containing heterocyclic compounds”, and the like.
Examples of the “tertiary amine compound” include triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n. -Tri (cyclo) alkylamines such as octylamine, tri-n-nonylamine, tri-n-decylamine, cyclohexyldimethylamine, dicyclohexylmethylamine, tricyclohexylamine; aniline, N-methylaniline, N, N-dimethylaniline Aromatic amines such as 2-methylaniline, 3-methylaniline, 4-methylaniline, 4-nitroaniline, 2,6-dimethylaniline, 2,6-diisopropylaniline, diphenylamine, triphenylamine, naphthylamine; Ethanolamine, Alkanolamines such as ethanolaniline; N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, 1,3-bis [1- ( 4-aminophenyl) -1-methylethyl] benzenetetramethylenediamine, 2,2-bis (4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4-aminophenyl) -2- (4-hydroxyphenyl) propane, 1,4-bis [1- (4-aminophenyl) -1-methylethyl] benzene, 1,3-bis [1- (4-aminophenyl) -1-methylethyl] benzene, bis (2-dimethylamino) Chill) ether, bis (2-diethylaminoethyl) ether.

  Examples of the “amide group-containing compound” include Nt-butoxycarbonyldi-n-octylamine, Nt-butoxycarbonyldi-n-nonylamine, Nt-butoxycarbonyldi-n-decylamine, N- t-butoxycarbonyldicyclohexylamine, Nt-butoxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-N-methyl-1-adamantylamine, N, N-di-t-butoxycarbonyl-1-adamantylamine N, N-di-t-butoxycarbonyl-N-methyl-1-adamantylamine, Nt-butoxycarbonyl-4,4′-diaminodiphenylmethane, N, N′-di-t-butoxycarbonylhexamethylenediamine N, N, N ′, N′-tetra-t-butoxycarbonylhexamethylene Diamine, N, N′-di-t-butoxycarbonyl-1,7-diaminoheptane, N, N′-di-t-butoxycarbonyl-1,8-diaminooctane, N, N′-di-t-butoxy Carbonyl-1,9-diaminononane, N, N′-di-t-butoxycarbonyl-1,10-diaminodecane, N, N′-di-t-butoxycarbonyl-1,12-diaminododecane, N, N ′ -Di-t-butoxycarbonyl-4,4'-diaminodiphenylmethane, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-methylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole Nt-butoxycarbonyl-pyrrolidine, Nt-butoxycarbonyl-piperidine, Nt-butoxycarbonyl- In addition to Nt-butoxycarbonyl group-containing amino compounds such as 4-hydroxy-piperidine, Nt-butoxycarbonyl-morpholine, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone and the like.

Examples of the “quaternary ammonium hydroxide compound” include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-n-butylammonium hydroxide, and the like.
Examples of the “nitrogen-containing heterocyclic compound” include imidazoles such as imidazole, 4-methylimidazole, 1-benzyl-2-methylimidazole, 4-methyl-2-phenylimidazole, benzimidazole, 2-phenylbenzimidazole; Pyridine, 2-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 4-ethylpyridine, 2-phenylpyridine, 4-phenylpyridine, 2-methyl-4-phenylpyridine, nicotine, nicotinic acid, nicotinamide, In addition to pyridines such as quinoline, 4-hydroxyquinoline, 8-oxyquinoline and acridine; piperazines such as piperazine and 1- (2-hydroxyethyl) piperazine, pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, 3 Piperidino-1,2-propanediol, morpholine, 4-methylmorpholine, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] octane.

  Of the nitrogen-containing heterocyclic compounds, tertiary amine compounds, amide group-containing compounds, and nitrogen-containing heterocyclic compounds are preferable. Among the tertiary amine compounds, alkanolamines are preferable, and among the amide group-containing compounds, N A t-butoxycarbonyl group-containing amino compound is preferred, and imidazoles are preferred among the nitrogen-containing heterocyclic compounds.

  The acid diffusion control agents can be used alone or in admixture of two or more. The compounding amount of the acid diffusion controller is usually 15 parts by weight or less, preferably 10 parts by weight or less, more preferably 5 parts by weight or less with respect to 100 parts by weight of the copolymer. In this case, when the compounding amount of the acid diffusion controller exceeds 15 parts by weight, the sensitivity as a resist and the developability of the radiation irradiated part tend to be lowered. If the amount of the acid diffusion controller is less than 0.001 part by weight, the pattern shape and dimensional fidelity as a resist may be lowered depending on the process conditions.

In addition, an alicyclic additive having an acid dissociable group or an alicyclic additive having no acid dissociable group is a component that further improves dry etching resistance, pattern shape, adhesion to a substrate, and the like. It is.
Examples of such alicyclic additives include 1-adamantanecarboxylic acid t-butyl, 1-adamantanecarboxylic acid t-butoxycarbonylmethyl, 1-adamantanecarboxylic acid α-butyrolactone ester, 1,3-adamantane dicarboxylic acid diester. -T-butyl, 1-adamantane acetate t-butyl, 1-adamantane acetate t-butoxycarbonylmethyl, 1,3-adamantanediacetate di-t-butyl, 2,5-dimethyl-2,5-di (adamantylcarbonyl) Adamantane derivatives such as oxy) hexane; deoxycholate t-butyl, deoxycholate t-butoxycarbonylmethyl, deoxycholate 2-ethoxyethyl, deoxycholate 2-cyclohexyloxyethyl, deoxycholate 3-oxocyclohexyl, Deoxychol Deoxycholic acid esters such as tetrahydropyranyl, deoxycholic acid mevalonolactone ester; lithocholic acid t-butyl, lithocholic acid t-butoxycarbonylmethyl, lithocholic acid 2-ethoxyethyl, lithocholic acid 2-cyclohexyloxyethyl, lithocholic acid Lithocholic acid esters such as 3-oxocyclohexyl, lithocholic acid tetrahydropyranyl, lithocholic acid mevalonolactone ester; dimethyl adipate, diethyl adipate, dipropyl adipate, di-n-butyl adipate, di-t-butyl adipate, etc. And alkyl carboxylic acid esters.
These alicyclic additives can be used alone or in admixture of two or more. The compounding quantity of an alicyclic additive is 50 parts weight or less normally with respect to 100 weight part of copolymers, Preferably it is 30 parts weight or less. In this case, when the blending amount of the alicyclic additive exceeds 50 parts by weight, the heat resistance as a resist tends to decrease.

Further, the surfactant as an additive is a component having an effect of improving coating property, striation, developability and the like.
Examples of such surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, and polyethylene glycol dilaurate. In addition to nonionic surfactants such as polyethylene glycol distearate, KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (manufactured by Kyoeisha Chemical Co., Ltd.), Ftop EF301, EF303, EF352 (manufactured by Tochem Products), Megafax F171, F173 (manufactured by Dainippon Ink and Chemicals), Fluorad FC430, FC431 (manufactured by Sumitomo 3M Limited), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 ( Asahi Glass Co., Ltd.).
These surfactants can be used alone or in admixture of two or more. The compounding amount of the surfactant is usually 2 parts by weight or less with respect to 100 parts by weight of the copolymer.

Further, the sensitizer as an additive has an action of absorbing radiation energy and transmitting the energy to the acid generator, thereby increasing the amount of acid generated. The radiation-sensitive resin composition It has the effect of improving the apparent sensitivity.
Examples of such sensitizers include carbazoles, benzophenones, rose bengals, anthracenes, phenols and the like.
These sensitizers can be used alone or in admixture of two or more. The blending amount of the sensitizer is preferably 50 parts by weight or less with respect to 100 parts by weight of the copolymer.
Furthermore, examples of additives other than those mentioned above include antihalation agents, adhesion assistants, storage stabilizers, antifoaming agents, and the like.

The radiation-sensitive resin composition of the present invention is usually dissolved in a solvent so that the total solid content is usually 3 to 50% by weight, preferably 5 to 25% by weight. A composition solution is prepared by filtering through a filter having a pore size of about 0.2 μm.
Examples of the solvent used in the preparation of the composition solution include linear or branched ketones such as 2-pentanone, 2-hexanone, 2-heptanone, and 2-octanone; cyclopentanone, cyclohexanone, and the like. Cyclic ketones; propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate; 2-hydroxypropionate alkyls such as methyl 2-hydroxypropionate and ethyl 2-hydroxypropionate; In addition to alkyl 3-alkoxypropionates such as methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate and ethyl 3-ethoxypropionate,

  Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, n-butyl acetate, methyl pyruvate , Ethyl pyruvate, N-methylpyrrolidone, γ-butyrolactone and the like.

  These solvents may be used alone or in admixture of two or more, but propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, 2-heptanone, cyclohexanone, γ-butyrolactone, ethyl 2-hydroxypropionate, 3-ethoxy It is preferable to contain at least one selected from ethyl propionate.

The radiation sensitive resin composition of the present invention is particularly useful as a chemically amplified resist. In particular, it is useful as a positive resist having etching resistance and excellent solubility in a developer after exposure.
In a chemically amplified resist, the acid-dissociable group in the resin is dissociated by the action of the acid generated from the acid generator by radiation irradiation to generate a carboxyl group. The solubility becomes high, and the irradiated portion is dissolved and removed by an alkali developer, and a positive resist pattern is obtained.
When forming a resist pattern from the radiation-sensitive resin composition of the present invention, the composition solution is coated with, for example, a silicon wafer or aluminum by an appropriate application means such as spin coating, cast coating or roll coating. A resist film is formed by coating on a substrate such as a wafer, and in some cases, a heat treatment (hereinafter referred to as “PB”) is performed in advance, and then a predetermined resist pattern is formed on the resist film. Irradiate. Examples of radiation used at this time include ultraviolet rays, KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), F ₂ excimer laser (wavelength 157 nm), EUV (extreme ultraviolet light, wavelength 13 nm, etc.), etc. Far ultraviolet rays, charged particle beams such as electron beams, and X-rays such as synchrotron radiation can be appropriately selected and used. Of these, far ultraviolet rays and electron beams are preferred. Moreover, irradiation conditions, such as irradiation amount, are suitably selected according to the compounding composition of a radiation sensitive resin composition, the kind of each additive, etc.
In the present invention, PEB is preferably performed in order to stably form a high-precision fine pattern. By this PEB, the dissociation reaction of the acid dissociable organic group in the copolymer proceeds smoothly. The heating condition of PEB varies depending on the composition of the radiation sensitive resin composition, but is usually 30 to 200 ° C, preferably 50 to 170 ° C.

In the present invention, in order to maximize the potential of the radiation-sensitive resin composition, for example, as disclosed in Japanese Patent Publication No. 6-12458, an organic or inorganic substrate is used. An antireflection film can also be formed, and in order to prevent the influence of basic impurities contained in the environmental atmosphere, as disclosed in, for example, JP-A-5-188598, A protective film can be provided on the substrate, or these techniques can be used in combination.
Next, the irradiated resist film is developed using an alkali developer to form a predetermined resist pattern.
As the alkaline developer, for example, an alkaline aqueous solution in which tetramethylammonium hydroxide is dissolved is preferable.
The concentration of the alkaline aqueous solution is usually 10% by weight or less. In this case, if the concentration of the alkaline aqueous solution exceeds 10% by weight, the non-irradiated part may be dissolved in the developer, which is not preferable.
In addition, an appropriate amount of a surfactant or the like can be added to the alkaline aqueous solution. In addition, after developing with an alkali developing solution, it is generally washed with water and dried.

単量体（Ｍ−１）３３．４９ｇ（４０モル％）、単量体（Ｍ−６）１５．４６ｇ（１０モル％）、単量体（Ｍ−７）５１．０５ｇ（５０モル％）を２−ブタノン２００ｇに溶解し、さらにジメチル２，２'−アゾビス（２−メチルプロピオネート）７．４１ｇを投入した単量体溶液を準備し、１００ｇの２−ブタノンを投入した１０００ｍｌの三口フラスコを３０分窒素パージする。窒素パージの後、反応釜を攪拌しながら８０℃に加熱し、事前に準備した上記単量体溶液を滴下漏斗を用いて３時間かけて滴下した。滴下開始を重合開始時間とし、重合反応を６時間実施した。重合終了後、重合溶液は水冷することにより３０℃以下に冷却し、２０００ｇのメタノールへ投入し、析出した白色粉末をろ別する。ろ別された白色粉末を２度４００ｇのメタノールにてスラリー上で洗浄した後、ろ別し、５０℃にて１７時間乾燥し、白色粉末の共重合体を得た（７３ｇ、収率７３％）。この共重合体はＭｗが５，５００、Ｍｗ／Ｍｎが１．６１であり、¹³Ｃ-ＮＭＲ分析の結果、単量体（Ｍ−１）由来の繰り返し単位：単量体（Ｍ−６）由来の繰り返し単位：単量体（Ｍ−７）由来の繰り返し単位の含有率が４０：９：５１（モル％）の共重合体であった。この共重合体を樹脂（Ａ−１）とする。 Example 1

Monomer (M-1) 33.49 g (40 mol%), monomer (M-6) 15.46 g (10 mol%), monomer (M-7) 51.05 g (50 mol%) Was dissolved in 200 g of 2-butanone, and a monomer solution into which 7.41 g of dimethyl 2,2′-azobis (2-methylpropionate) was further added was prepared, and 1000 ml of three necks charged with 100 g of 2-butanone was prepared. The flask is purged with nitrogen for 30 minutes. After purging with nitrogen, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise using a dropping funnel over 3 hours. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution is cooled with water to 30 ° C. or less, put into 2000 g of methanol, and the precipitated white powder is filtered off. The filtered white powder was washed twice with 400 g of methanol on the slurry, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder copolymer (73 g, 73% yield). ). This copolymer has Mw of 5,500 and Mw / Mn of 1.61, and as a result of ¹³ C-NMR analysis, the repeating unit derived from monomer (M-1): monomer (M-6) Derived repeating unit: It was a copolymer having a content of repeating units derived from the monomer (M-7) of 40: 9: 51 (mol%). This copolymer is referred to as “resin (A-1)”.

単量体（Ｍ−１）２４．６７ｇ（３０モル％）、単量体（Ｍ−６）１５．１８ｇ（１０モル％）、単量体（Ｍ−７）６０．１６ｇ（６０モル％）を２−ブタノン２００ｇに溶解し、さらにジメチル２，２'−アゾビス（２−メチルプロピオネート）７．２７ｇを投入した単量体溶液を準備し、１００ｇの２−ブタノンを投入した１０００ｍｌの三口フラスコを３０分窒素パージする。窒素パージの後、反応釜を攪拌しながら８０℃に加熱し、事前に準備した上記単量体溶液を滴下漏斗を用いて３時間かけて滴下した。滴下開始を重合開始時間とし、重合反応を６時間実施した。重合終了後、重合溶液は水冷することにより３０℃以下に冷却し、２０００ｇのメタノールへ投入し、析出した白色粉末をろ別する。ろ別された白色粉末を２度４００ｇのメタノールにてスラリー上で洗浄した後、ろ別し、５０℃にて１７時間乾燥し、白色粉末の共重合体を得た（７１ｇ、収率７１％）。この共重合体はＭｗが５，３００、Ｍｗ／Ｍｎが１．５６であり、¹³Ｃ-ＮＭＲ分析の結果、単量体（Ｍ−１）由来の繰り返し単位：単量体（Ｍ−６）由来の繰り返し単位：単量体（Ｍ−７）由来の繰り返し単位の含有率が３０：９：６１（モル％）の共重合体であった。この共重合体を樹脂（Ａ−２）とする。 Example 2

Monomer (M-1) 24.67 g (30 mol%), Monomer (M-6) 15.18 g (10 mol%), Monomer (M-7) 60.16 g (60 mol%) Was dissolved in 200 g of 2-butanone, and a monomer solution into which 7.27 g of dimethyl 2,2′-azobis (2-methylpropionate) was further added was prepared, and 1000 ml of three necks charged with 100 g of 2-butanone was prepared. The flask is purged with nitrogen for 30 minutes. After purging with nitrogen, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise using a dropping funnel over 3 hours. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution is cooled with water to 30 ° C. or less, put into 2000 g of methanol, and the precipitated white powder is filtered off. The filtered white powder was washed twice with 400 g of methanol on the slurry, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder copolymer (71 g, yield 71%). ). This copolymer has Mw of 5,300 and Mw / Mn of 1.56. As a result of ¹³ C-NMR analysis, the repeating unit derived from the monomer (M-1): monomer (M-6) Derived repeating unit: It was a copolymer having a content of repeating units derived from the monomer (M-7) of 30: 9: 61 (mol%). This copolymer is referred to as “resin (A-2)”.

単量体（Ｍ−２）３５．１７ｇ（４０モル％）、単量体（Ｍ−６）１５．０７ｇ（１０モル％）、単量体（Ｍ−７）４９．１１ｇ（５０モル％）を２−ブタノン２００ｇに溶解し、さらにジメチル２，２'−アゾビス（２−メチルプロピオネート）５．５８ｇを投入した単量体溶液を準備し、１００ｇの２−ブタノンを投入した１０００ｍｌの三口フラスコを３０分窒素パージする。窒素パージの後、反応釜を攪拌しながら８０℃に加熱し、事前に準備した上記単量体溶液を滴下漏斗を用いて３時間かけて滴下した。滴下開始を重合開始時間とし、重合反応を６時間実施した。重合終了後、重合溶液は水冷することにより３０℃以下に冷却し、２０００ｇのメタノールへ投入し、析出した白色粉末をろ別する。ろ別された白色粉末を２度４００ｇのメタノールにてスラリー上で洗浄した後、ろ別し、５０℃にて１７時間乾燥し、白色粉末の共重合体を得た（７３ｇ、収率７３％）。この共重合体はＭｗが５，４００、Ｍｗ／Ｍｎが１．６３であり、¹³Ｃ-ＮＭＲ分析の結果、単量体（Ｍ−２）由来の繰り返し単位：単量体（Ｍ−６）由来の繰り返し単位：単量体（Ｍ−７）由来の繰り返し単位の含有率が４１：９：５０（モル％）の共重合体であった。この共重合体を樹脂（Ａ−３）とする。 Example 3

Monomer (M-2) 35.17 g (40 mol%), monomer (M-6) 15.07 g (10 mol%), monomer (M-7) 49.11 g (50 mol%) Was dissolved in 200 g of 2-butanone, and a monomer solution containing 5.58 g of dimethyl 2,2′-azobis (2-methylpropionate) was prepared, and 1000 ml of three necks charged with 100 g of 2-butanone was prepared. The flask is purged with nitrogen for 30 minutes. After purging with nitrogen, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise using a dropping funnel over 3 hours. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution is cooled with water to 30 ° C. or less, put into 2000 g of methanol, and the precipitated white powder is filtered off. The filtered white powder was washed twice with 400 g of methanol on the slurry, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder copolymer (73 g, 73% yield). ). This copolymer has Mw of 5,400 and Mw / Mn of 1.63. As a result of ¹³ C-NMR analysis, the repeating unit derived from the monomer (M-2): monomer (M-6) Derived repeating unit: It was a copolymer having a content of repeating units derived from the monomer (M-7) of 41: 9: 50 (mol%). This copolymer is referred to as “resin (A-3)”.

単量体（Ｍ−３）３３．６７ｇ（３５モル％）、単量体（Ｍ−６）２０．７２ｇ（１５モル％）、単量体（Ｍ−７）４５．６２ｇ（５０モル％）を２−ブタノン２００ｇに溶解し、さらにジメチル２，２'−アゾビス（２−メチルプロピオネート）６．６２ｇを投入した単量体溶液を準備し、１００ｇの２−ブタノンを投入した１０００ｍｌの三口フラスコを３０分窒素パージする。窒素パージの後、反応釜を攪拌しながら８０℃に加熱し、事前に準備した上記単量体溶液を滴下漏斗を用いて３時間かけて滴下した。滴下開始を重合開始時間とし、重合反応を６時間実施した。重合終了後、重合溶液は水冷することにより３０℃以下に冷却し、２０００ｇのメタノールへ投入し、析出した白色粉末をろ別する。ろ別された白色粉末を２度４００ｇのメタノールにてスラリー上で洗浄した後、ろ別し、５０℃にて１７時間乾燥し、白色粉末の共重合体を得た（７８ｇ、収率７８％）。この共重合体はＭｗが５，７００、Ｍｗ／Ｍｎが１．６０であり、¹³Ｃ-ＮＭＲ分析の結果、単量体（Ｍ−３）由来の繰り返し単位：単量体（Ｍ−６）由来の繰り返し単位：単量体（Ｍ−７）由来の繰り返し単位の含有率が３２：１４：５４（モル％）の共重合体であった。この共重合体を樹脂（Ａ−４）とする。 Example 4

Monomer (M-3) 33.67 g (35 mol%), monomer (M-6) 20.72 g (15 mol%), monomer (M-7) 45.62 g (50 mol%) Was dissolved in 200 g of 2-butanone, and a monomer solution into which 6.62 g of dimethyl 2,2′-azobis (2-methylpropionate) was further added was prepared, and 1000 ml of three necks charged with 100 g of 2-butanone was prepared. The flask is purged with nitrogen for 30 minutes. After purging with nitrogen, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise using a dropping funnel over 3 hours. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution is cooled with water to 30 ° C. or less, put into 2000 g of methanol, and the precipitated white powder is filtered off. The filtered white powder was washed twice with 400 g of methanol on the slurry, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder copolymer (78 g, yield 78%). ). This copolymer has Mw of 5,700 and Mw / Mn of 1.60. As a result of ¹³ C-NMR analysis, the repeating unit derived from the monomer (M-3): monomer (M-6) Derived repeating unit: It was a copolymer having a content of repeating units derived from the monomer (M-7) of 32:14:54 (mol%). This copolymer is referred to as “resin (A-4)”.

単量体（Ｍ−３）３９．３０ｇ（４０モル％）、単量体（Ｍ−６）１４．１１ｇ（１０モル％）、単量体（Ｍ−７）４６．５９ｇ（５０モル％）を２−ブタノン２００ｇに溶解し、さらにアゾビスイソブチロニトリル５．６４ｇを投入した単量体溶液を準備し、１００ｇの２−ブタノンを投入した１０００ｍｌの三口フラスコを３０分窒素パージする。窒素パージの後、反応釜を攪拌しながら８０℃に加熱し、事前に準備した上記単量体溶液を滴下漏斗を用いて３時間かけて滴下した。滴下開始を重合開始時間とし、重合反応を６時間実施した。重合終了後、重合溶液は水冷することにより３０℃以下に冷却し、２０００ｇのメタノールへ投入し、析出した白色粉末をろ別する。ろ別された白色粉末を２度４００ｇのメタノールにてスラリー上で洗浄した後、ろ別し、５０℃にて１７時間乾燥し、白色粉末の共重合体を得た（７６ｇ、収率７６％）。この共重合体はＭｗが５，５００、Ｍｗ／Ｍｎが１．５８であり、¹³Ｃ-ＮＭＲ分析の結果、単量体（Ｍ−３）由来の繰り返し単位：単量体（Ｍ−６）由来の繰り返し単位：単量体（Ｍ−７）由来の繰り返し単位の含有率が３７：９：５４（モル％）の共重合体であった。この共重合体を共重合体（Ａ−５）とする。 Example 5

Monomer (M-3) 39.30 g (40 mol%), monomer (M-6) 14.11 g (10 mol%), monomer (M-7) 46.59 g (50 mol%) Is dissolved in 200 g of 2-butanone, and a monomer solution charged with 5.64 g of azobisisobutyronitrile is prepared. A 1000 ml three-necked flask charged with 100 g of 2-butanone is purged with nitrogen for 30 minutes. After purging with nitrogen, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise using a dropping funnel over 3 hours. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution is cooled with water to 30 ° C. or less, put into 2000 g of methanol, and the precipitated white powder is filtered off. The filtered white powder was washed twice with 400 g of methanol on the slurry, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder copolymer (76 g, yield 76%). ). This copolymer has Mw of 5,500 and Mw / Mn of 1.58. As a result of ¹³ C-NMR analysis, the repeating unit derived from the monomer (M-3): monomer (M-6) Derived repeating unit: It was a copolymer having a content of repeating units derived from the monomer (M-7) of 37: 9: 54 (mol%). This copolymer is referred to as “copolymer (A-5)”.

単量体（Ｍ−２）３５．２０ｇ（４０モル％）、単量体（Ｍ−４）９．８８ｇ（１０モル％）、単量体（Ｍ−６）１５．１８ｇ（１０モル％）、単量体（Ｍ−７）３９．８５ｇ（４０モル％）を２−ブタノン２００ｇに溶解し、さらにジメチル２，２'−アゾビス（２−メチルプロピオネート）７．２３ｇを投入した単量体溶液を準備し、１００ｇの２−ブタノンを投入した１０００ｍｌの三口フラスコを３０分窒素パージする。窒素パージの後、反応釜を攪拌しながら８０℃に加熱し、事前に準備した上記単量体溶液を滴下漏斗を用いて３時間かけて滴下した。滴下開始を重合開始時間とし、重合反応を６時間実施した。重合終了後、重合溶液は水冷することにより３０℃以下に冷却し、２０００ｇのメタノールへ投入し、析出した白色粉末をろ別する。ろ別された白色粉末を２度４００ｇのメタノールにてスラリー上で洗浄した後、ろ別し、５０℃にて１７時間乾燥し、白色粉末の共重合体を得た（６９ｇ、収率６９％）。この共重合体はＭｗが５，３００、Ｍｗ／Ｍｎが１．６２であり、¹³Ｃ-ＮＭＲ分析の結果、単量体（Ｍ−２）由来の繰り返し単位：単量体（Ｍ−４）由来の繰り返し単位：単量体（Ｍ−６）由来の繰り返し単位：単量体（Ｍ−７）由来の繰り返し単位の含有率が４２：９：９：５０（モル％）の共重合体であった。この共重合体を樹脂（Ａ−６）とする。 Example 6

Monomer (M-2) 35.20 g (40 mol%), monomer (M-4) 9.88 g (10 mol%), monomer (M-6) 15.18 g (10 mol%) Monomer (M-7) 39.85 g (40 mol%) dissolved in 2-butanone 200 g and dimethyl 2,2′-azobis (2-methylpropionate) 7.23 g A body solution is prepared and a 1000 ml three-necked flask charged with 100 g of 2-butanone is purged with nitrogen for 30 minutes. After purging with nitrogen, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise using a dropping funnel over 3 hours. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution is cooled with water to 30 ° C. or less, put into 2000 g of methanol, and the precipitated white powder is filtered off. The filtered white powder was washed twice with 400 g of methanol on the slurry, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder copolymer (69 g, yield 69%). ). This copolymer has Mw of 5,300 and Mw / Mn of 1.62, and as a result of ¹³ C-NMR analysis, the repeating unit derived from monomer (M-2): monomer (M-4) A repeating unit derived from: a copolymer having a repeating unit derived from the monomer (M-6): a repeating unit derived from the monomer (M-7) having a content of 42: 9: 9: 50 (mol%). there were. This copolymer is referred to as “resin (A-6)”.

単量体（Ｍ−８）３３．４９ｇ（４０モル％）、単量体（Ｍ−６）１５．４６ｇ（１０モル％）、単量体（Ｍ−７）５１．０５ｇ（５０モル％）を２−ブタノン２００ｇに溶解し、さらにジメチル２，２'−アゾビス（２−メチルプロピオネート）７．４１ｇを投入した単量体溶液を準備し、１００ｇの２−ブタノンを投入した１０００ｍｌの三口フラスコを３０分窒素パージする。窒素パージの後、反応釜を攪拌しながら８０℃に加熱し、事前に準備した上記単量体溶液を滴下漏斗を用いて３時間かけて滴下した。滴下開始を重合開始時間とし、重合反応を６時間実施した。重合終了後、重合溶液は水冷することにより３０℃以下に冷却し、２０００ｇのメタノールへ投入し、析出した白色粉末をろ別する。ろ別された白色粉末を２度４００ｇのメタノールにてスラリー上で洗浄した後、ろ別し、５０℃にて１７時間乾燥し、白色粉末の共重合体を得た（６７ｇ、収率６７％）。この共重合体はＭｗが５，０００、Ｍｗ／Ｍｎが１．５９であり、¹³Ｃ-ＮＭＲ分析の結果、単量体（Ｍ−８）由来の繰り返し単位：単量体（Ｍ−６）由来の繰り返し単位：単量体（Ｍ−７）由来の繰り返し単位の含有率が３９：９：５２（モル％）の共重合体であった。この共重合体を樹脂（Ａ−７）とする。 Example 7

Monomer (M-8) 33.49 g (40 mol%), monomer (M-6) 15.46 g (10 mol%), monomer (M-7) 51.05 g (50 mol%) Was dissolved in 200 g of 2-butanone, and a monomer solution into which 7.41 g of dimethyl 2,2′-azobis (2-methylpropionate) was further added was prepared, and 1000 ml of three necks charged with 100 g of 2-butanone was prepared. The flask is purged with nitrogen for 30 minutes. After purging with nitrogen, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise using a dropping funnel over 3 hours. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution is cooled with water to 30 ° C. or less, put into 2000 g of methanol, and the precipitated white powder is filtered off. The filtered white powder was washed twice with 400 g of methanol on the slurry, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder copolymer (67 g, 67% yield). ). This copolymer has Mw of 5,000 and Mw / Mn of 1.59. As a result of ¹³ C-NMR analysis, the repeating unit derived from the monomer (M-8): monomer (M-6) Originated repeating unit: It was a copolymer having a content of repeating units derived from the monomer (M-7) of 39: 9: 52 (mol%). This copolymer is referred to as “resin (A-7)”.

単量体（Ｍ−２）３５．６２ｇ（４０モル％）、単量体（Ｍ−９）１３．９８ｇ（１０モル％）、単量体（Ｍ−７）５０．４１ｇ（５０モル％）を２−ブタノン２００ｇに溶解し、さらにジメチル２，２'−アゾビス（２−メチルプロピオネート）７．３１ｇを投入した単量体溶液を準備し、１００ｇの２−ブタノンを投入した１０００ｍｌの三口フラスコを３０分窒素パージする。窒素パージの後、反応釜を攪拌しながら８０℃に加熱し、事前に準備した上記単量体溶液を滴下漏斗を用いて３時間かけて滴下した。滴下開始を重合開始時間とし、重合反応を６時間実施した。重合終了後、重合溶液は水冷することにより３０℃以下に冷却し、２０００ｇのメタノールへ投入し、析出した白色粉末をろ別する。ろ別された白色粉末を２度４００ｇのメタノールにてスラリー上で洗浄した後、ろ別し、５０℃にて１７時間乾燥し、白色粉末の共重合体を得た（７２ｇ、収率７２％）。この共重合体はＭｗが５，５００、Ｍｗ／Ｍｎが１．６４であり、¹³Ｃ-ＮＭＲ分析の結果、単量体（Ｍ−２）由来の繰り返し単位：単量体（Ｍ−９）由来の繰り返し単位：単量体（Ｍ−７）由来の繰り返し単位の含有率が３９：１０：５１（モル％）の共重合体であった。この共重合体を樹脂（Ａ−８）とする。 Example 8

Monomer (M-2) 35.62 g (40 mol%), monomer (M-9) 13.98 g (10 mol%), monomer (M-7) 50.41 g (50 mol%) Was dissolved in 200 g of 2-butanone, and then a monomer solution into which 7.31 g of dimethyl 2,2′-azobis (2-methylpropionate) was added was prepared, and 1000 ml of three necks charged with 100 g of 2-butanone was prepared. The flask is purged with nitrogen for 30 minutes. After purging with nitrogen, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise using a dropping funnel over 3 hours. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution is cooled with water to 30 ° C. or less, put into 2000 g of methanol, and the precipitated white powder is filtered off. The filtered white powder was washed twice with 400 g of methanol on the slurry, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder copolymer (72 g, yield 72%). ). This copolymer has Mw of 5,500 and Mw / Mn of 1.64. As a result of ¹³ C-NMR analysis, the repeating unit derived from the monomer (M-2): monomer (M-9) Derived repeating unit: It was a copolymer having a content of repeating units derived from the monomer (M-7) of 39:10:51 (mol%). This copolymer is referred to as “resin (A-8)”.

単量体（Ｍ−２）２７．１０ｇ（３０モル％）、単量体（Ｍ−５）２１．７５ｇ（２０モル％）と単量体（Ｍ−７）５１．１４ｇ（５０モル％）を２−ブタノン２００ｇに溶解し、更にジメチル２，２'−アゾビス（２−メチルプロピオネート）５．３０ｇを投入したモノマー溶液を準備し、１００ｇの２−ブタノンを投入した１０００ｍｌの三口フラスコを３０分窒素パージする。窒素パージの後、反応釜を攪拌しながら８０℃に加熱し、事前に準備した上記単量体溶液を滴下漏斗を用いて３時間かけて滴下した。滴下開始を重合開始時間とし、重合反応を６時間実施した。重合終了後、重合溶液は水冷することにより３０℃以下に冷却し、２０００ｇのメタノールへ投入し、析出した白色粉末をろ別する。ろ別された白色粉末を２度４００ｇのメタノールにてスラリー上で洗浄した後、ろ別し、５０℃にて１７時間乾燥し、白色粉末の共重合体を得た（７７ｇ、収率７７％）。この共重合体はＭｗが８，９００、Ｍｗ／Ｍｎが１．８０であり、¹³Ｃ-ＮＭＲ分析の結果、単量体（Ｍ−２）由来の繰り返し単位：単量体（Ｍ−５）由来の繰り返し単位：単量体（Ｍ−７）由来の繰り返し単位の含有率が２９：１９：５２（モル％）の共重合体であった。この共重合体を樹脂（Ｒ−１）とする。 Comparative Example 1

Monomer (M-2) 27.10 g (30 mol%), monomer (M-5) 21.75 g (20 mol%) and monomer (M-7) 51.14 g (50 mol%) Was dissolved in 200 g of 2-butanone, and a monomer solution containing 5.30 g of dimethyl 2,2′-azobis (2-methylpropionate) was prepared, and a 1000 ml three-necked flask containing 100 g of 2-butanone was prepared. Purge with nitrogen for 30 minutes. After purging with nitrogen, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise using a dropping funnel over 3 hours. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution is cooled with water to 30 ° C. or less, put into 2000 g of methanol, and the precipitated white powder is filtered off. The filtered white powder was washed twice with 400 g of methanol on the slurry, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder copolymer (77 g, yield 77%). ). This copolymer has Mw of 8,900 and Mw / Mn of 1.80. As a result of ¹³ C-NMR analysis, the repeating unit derived from the monomer (M-2): monomer (M-5) The repeating unit derived from: a copolymer having a content of repeating unit derived from the monomer (M-7) of 29:19:52 (mol%). This copolymer is referred to as “resin (R-1)”.

Examples 9 to 18 and Comparative Example 2
Each radiation-sensitive resin composition was prepared by blending each resin obtained in Examples 1 to 8 and Comparative Example 1, the acid generator shown below, and other components in the proportions shown in Table 1. Obtained. Various evaluation was performed using the obtained radiation sensitive resin composition. The evaluation results are shown in Table 2. Here, the part is based on weight unless otherwise specified.
Acid generator (B)
(B-1): Triphenylsulfonium nonafluoro-n-butanesulfonate (B-2): 4-n-butoxy-1-naphthyltetrahydrothiophenium nonafluoro-n-butanesulfonate (B-3): 4- Cyclohexylphenyldiphenylsulfonium / nonafluoro-n-butanesulfonate acid diffusion controller (C)
(C-1): Phenylbenzimidazole (C-2): Triethanolamine solvent (D)
(D-1): Propylene glycol monomethyl ether acetate

Evaluation Method (1) Sensitivity When exposure is performed with an ArF light source, a silicon wafer (ARC29) having an ARC29 (manufactured by Brewer Science) film with a film thickness of 77 nm formed on the wafer surface is used. A Nikon ArF excimer laser exposure device (numerical aperture of 0.75) is applied to a 200 nm-thick resist film formed by spin coating on a hot plate and performing PB on a hot plate at 120 ° C. for 1 minute. Used and exposed through a mask pattern. Thereafter, PEB is performed at 120 ° C. for 1 minute, and then developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution at 25 ° C. for 60 seconds, washed with water and dried to form a positive resist pattern. Formed. At this time, the exposure amount for forming a line-and-space pattern (1L1S) having a line width of 100 nm with a one-to-one line width was defined as the optimum exposure amount, and this optimum exposure amount was defined as the sensitivity.
(2) Resolution The minimum line-and-space pattern dimension that can be resolved with the optimum exposure dose is taken as the resolution.
(3) Radiation transmittance The composition solution was applied to quartz glass by spin coating, and PB was performed at 120 ° C. for 1 minute on a hot plate maintained at the temperature conditions shown in Table 3 for a film thickness of 300 nm. For the resist film, the radiation transmittance was calculated from the absorbance at a wavelength of 193 nm and used as a measure of transparency in the far ultraviolet region.
(4) Line edge roughness (LER)
When observing the 100nm 1L / 1S pattern resolved at the optimal exposure dose, the line width is observed at an arbitrary point when observing from the top of the pattern with Hitachi SEM: S9260, and the measurement variation is expressed in 3 sigma. When the value was 10 nm or more, the case where the value was less than 10 nm was expressed as good.
(5) Etching resistance The resist film formed as described above is subjected to an oxygen ashing process at 300 W for 30 seconds using a barrel-type oxygen plasma ashing apparatus “PR-501” (manufactured by Yamato Kagaku Co., Ltd.). The case where the etching amount per 30 seconds calculated from the difference between the film thickness of the resist film and the film thickness of the resist film after the treatment was smaller than 150 nm was expressed as ◯, and the case where the etching amount was larger was expressed as x.

  Since the radiation-sensitive resin composition of the present invention is excellent in etching resistance and solubility in an alkaline developer, it is extremely useful as a chemically amplified resist for semiconductor device production, which is expected to be further refined from now on. is there.

Claims (3)

Containing the repeating unit (i) represented by the formula (1) and the repeating unit (ii) having an acid dissociable group, being insoluble in alkali or hardly soluble in alkali, and easily soluble in alkali by the action of an acid; A copolymer having a polystyrene-reduced weight average molecular weight of 1,000 to 200,000 by gel permeation chromatography.

(R ¹ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a trifluoromethyl group, X represents a single bond or a divalent organic group, Y represents a hydrogen atom or a group represented by the following formula (2) Wherein at least one Y is represented by formula (2),

R ² represents a divalent organic group, and R ³ represents a linear or branched alkyl group having 1 to 6 carbon atoms, an alicyclic hydrocarbon group having 3 to 6 carbon atoms, or a phenyl group. ) The copolymer according to claim 1, wherein the repeating unit (ii) having the acid dissociable group is represented by the following formula (3).

(R ⁴ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a trifluoromethyl group, and R ⁵ is independently a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or Represents a linear or branched alkyl group having 1 to 4 carbon atoms, and at least one of R ⁵ is the alicyclic hydrocarbon group or a derivative thereof, or any two R ⁵ are bonded to each other Then, a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof is formed together with the carbon atoms to which each is bonded, and the remaining R ⁵ is linear or branched having 1 to 4 carbon atoms. An alkyl group in the form of a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof. A radiation-sensitive resin composition comprising a resin that is insoluble in alkali or hardly soluble in alkali and easily soluble in alkali by the action of an acid, and a radiation-sensitive acid generator,
A radiation-sensitive resin composition, wherein the resin is at least one copolymer selected from the copolymers according to claim 1 and claim 2.