JP4848843B2 - Polymer, radiation-sensitive resin composition, and resist pattern forming method - Google Patents

Description

  The present invention relates to a novel polymer, a radiation-sensitive resin composition, and a resist pattern forming method, and more particularly, radiation between a lens and a photoresist film via an immersion exposure liquid having a refractive index greater than that of air at a wavelength of 193 nm. The present invention relates to a radiation-sensitive resin composition applied to a resist pattern including immersion exposure. More specifically, the present invention relates to a radiation-sensitive resin composition for immersion exposure that has a good pattern shape, excellent depth of focus, and a small amount of eluate in water that has come into contact with the immersion exposure.

In the field of microfabrication represented by the manufacture of integrated circuit elements, in order to obtain a higher degree of integration, recently, a lithography technique capable of microfabrication at a level of 100 nm or less is required. However, in the conventional lithography process, near ultraviolet rays such as i rays are generally used as radiation, and it is said that fine processing at the subquarter micron level is extremely difficult with this near ultraviolet rays. Therefore, in order to enable microfabrication at a level of 200 nm or less, use of radiation having a shorter wavelength is being studied. Examples of such short-wavelength radiation include an emission line spectrum of a mercury lamp, far-ultraviolet rays typified by an excimer laser, an X-ray, an electron beam, and the like. Among these, a KrF excimer laser (wavelength 248 nm) is particularly preferable. ) Or ArF excimer laser (wavelength 193 nm) has attracted attention.
As a resist suitable for irradiation with such an excimer laser, a component having an acid-dissociable functional group and a component that generates acid upon irradiation with radiation (hereinafter referred to as “exposure”) (hereinafter referred to as “acid generator”). )) And a resist utilizing the chemical amplification effect (hereinafter referred to as “chemically amplified resist”) have been proposed. As the chemically amplified resist, for example, a resist containing a resin having a t-butyl ester group of carboxylic acid or a t-butyl carbonate group of phenol and an acid generator has been proposed. In this resist, a t-butyl ester group or t-butyl carbonate group present in the resin is dissociated by the action of an acid generated by exposure, and the resin has an acidic group composed of a carboxyl group or a phenolic hydroxyl group. As a result, the phenomenon that the exposed region of the resist film becomes readily soluble in an alkali developer is utilized.

  In such a lithography process, further fine pattern formation (for example, a fine resist pattern having a line width of about 90 nm) will be required in the future. In order to achieve such a pattern formation finer than 90 nm, it is conceivable to shorten the light source wavelength of the exposure apparatus and increase the numerical aperture (NA) of the lens as described above. However, a new expensive exposure apparatus is required to shorten the light source wavelength. Further, when the lens has a high NA, the resolution and the depth of focus are in a trade-off relationship. Therefore, there is a problem that the depth of focus decreases even if the resolution is increased.

  Recently, a liquid immersion lithography (liquid immersion lithography) method has been reported as a lithography technique that can solve such problems. In this method, at the time of exposure, a liquid refractive index medium (immersion liquid) such as pure water or a fluorine-based inert liquid having a predetermined thickness is interposed between at least the resist film between the lens and the resist film on the substrate. Is. In this method, a light source having the same exposure wavelength can be used by replacing the exposure optical path space, which has conventionally been an inert gas such as air or nitrogen, with a liquid having a higher refractive index (n), such as pure water. Similar to the case of using a light source with a shorter wavelength or the case of using a high NA lens, high resolution is achieved and there is no reduction in the depth of focus. By using such immersion exposure, it is possible to realize the formation of a resist pattern that is low in cost, excellent in high resolution, and excellent in depth of focus, using a lens mounted on an existing apparatus. It is attracting a lot of attention.

However, in the above-described immersion exposure process, when the refractive index of the high refractive index liquid (immersion liquid) is higher than the refractive index of the resist film, for example, it becomes difficult for light to enter the resist film from the immersion liquid by Snell's law, There is a possibility that basic performance such as sensitivity will deteriorate. If this difference in refractive index is large, the light will eventually be totally reflected at the interface between the immersion liquid and the resist film and will not be incident on the resist film at all, and sufficient sensitivity will not be obtained. There is a problem that the throughput is significantly reduced.
Therefore, a resin for resist or a resist film having a refractive index higher than that of the immersion liquid is used as the resin used in the immersion exposure apparatus particularly when an immersion liquid having a refractive index of 1.70 or more at 193 nm of a normal resist film is used. Therefore, materials such as those described in Non-Patent Document 1 and Non-Patent Document 2 have begun to be proposed.
However, these materials have a high refractive index at 193 nm, but do not have a function as a resist. Therefore, there is an urgent need to provide a material that has a refractive index higher than that of a normal resist material (1.70 at 193 nm) and can be patterned as a resist.

SPIE 2006 61530H SPIE 2006 61531L

  The present invention has been made to cope with such problems, and includes a novel polymer having a refractive index at 193 nm of not less than 1.72 and functioning as a chemically amplified resist resin, and the polymer. An object is to provide a radiation-sensitive resin composition for immersion exposure and a resist pattern forming method using the radiation-sensitive resin composition for immersion exposure.

式（１）において、Ｒ¹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、Ａは単結合または２価の連結基を表し、３つのＸはそれぞれ独立に酸素原子または硫黄原子を表し、少なくとも１つのＸが硫黄原子を表し、Ｒ²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、または炭素数４〜２０の脂環式炭化水素基を表す。

式（２）において、Ｒ³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Ｒ³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Ｒ³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Ｒ³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。 The polymer of the present invention contains a repeating unit represented by the following formula (1) and a repeating unit obtained from a monomer having a side chain represented by the following formula (2), and is obtained by gel permeation chromatography. polystyrene equivalent weight average molecular weight of Ri der 1,000 to 100,000, based on all repeating units, the content of the repeating unit is 10 to 90 mol% of the following formula (1), the following formula (2) the content of recurring units derived from monomers and wherein 10 to 90 mol% der Rukoto having a side chain represented in.

In Formula (1), R ¹ represents a hydrogen atom, a methyl group, or a trifluoromethyl group, A represents a single bond or a divalent linking group, and three Xs independently represent an oxygen atom or a sulfur atom. , At least one X represents a sulfur atom, and R ² represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alicyclic hydrocarbon group having 4 to 20 carbon atoms.

In the formula (2), R ³ each independently represents a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or a linear or branched alkyl group having 1 to 4 carbon atoms. And at least one of R ³ is the alicyclic hydrocarbon group or a derivative thereof, or any two R ³ are bonded to each other, and together with the carbon atom to which each is bonded, 4 to 20 carbon atoms. A divalent alicyclic hydrocarbon group or a derivative thereof, and the remaining R ³ is a linear or branched alkyl group having 1 to 4 carbon atoms, or a monovalent alicyclic ring having 4 to 20 carbon atoms. Represents a hydrocarbon group or a derivative thereof.

The radiation-sensitive resin composition of the present invention is a radiation-sensitive resin composition containing a resin (A) that becomes alkali-soluble by the action of an acid and a radiation-sensitive acid generator (B), and the resin (A) is the above polymer.
Moreover, the refractive index in wavelength 193nm of the resist film formed with the said radiation sensitive resin composition is 1.72 or more, It is characterized by the above-mentioned.

  The resist pattern forming method of the present invention is a resist pattern forming method including immersion exposure in which radiation is irradiated between a lens and a photoresist film through an immersion exposure liquid having a refractive index at a wavelength of 193 nm larger than that of air. The photoresist film is formed using the radiation-sensitive resin composition, and the liquid for immersion exposure is a liquid whose refractive index at 193 nm is higher than the refractive index at 193 nm of water. .

Since the novel polymer of the present invention contains a repeating unit having a specific skeleton represented by the formula (1), a photoresist film obtained from a radiation-sensitive resin composition for immersion exposure using this polymer Has a refractive index of 193 nm or more due to a specific skeleton.
For this reason, the radiation sensitive resin composition for immersion exposure containing this polymer can be applied when a high refractive index immersion liquid, which is a next generation immersion technique, is used.

式（１）において、Ａは単結合または２価の連結基を表す。２価の連結基は、好ましくは２価の炭化水素基であり、２価の炭化水素基の中でも好ましくは鎖状または環状の炭化水素基である。また、アルキレングリコール基、アルキレンエステル基であってもよい。 鎖状または環状の炭化水素基としては、メチレン基、エチレン基、１，３−プロピレン基もしくは１，２−プロピレン基などのプロピレン基、テトラメチレン基、ペンタメチレン基、ヘキサメチレン基、ヘプタメチレン基、オクタメチレン基、ノナメチレン基、デカメチレン基、ウンデカメチレン基、ドデカメチレン基、トリデカメチレン基、テトラデカメチレン基、ペンタデカメチレン基、ヘキサデカメチレン基、ヘプタデカメチレン基、オクタデカメチレン基、ノナデカメチレン基、インサレン基、１−メチル−１，３−プロピレン基、２−メチル１，３−プロピレン基、２−メチル−１，２−プロピレン基、１−メチル−１，４−ブチレン基、２−メチル−１，４−ブチレン基、メチリデン基、エチリデン基、プロピリデン基、または、２−プロピリデン基等の飽和鎖状炭化水素基、１，３−シクロブチレン基などのシクロブチレン基、１，３−シクロペンチレン基などのシクロペンチレン基、１，４−シクロヘキシレン基などのシクロヘキシレン基、１，５−シクロオクチレン基などのシクロオクチレン基等の炭素数３〜１０のシクロアルキレン基などの単環式炭化水素環基、１，４−ノルボルニレン基もしくは２，５−ノルボルニレン基などのノルボルニレン基、１，５−アダマンチレン基、２，６−アダマンチレン基などのアダマンチレン基等の２〜４環式炭素数４〜３０の炭化水素環基などの架橋環式炭化水素環基等が挙げられる。
鎖状または環状の炭化水素基の中で、好ましい基はメチレン基、エチレン基である。 Novel Polymer The novel polymer of the present invention is a resin (A) [hereinafter referred to as “resin (A)”) that becomes readily soluble in alkali by the action of an acid. ] Can be used. The novel polymer contains a repeating unit represented by the formula (1) (hereinafter referred to as “repeating unit (1)”) as an essential unit, and is alkali-insoluble or alkali-insoluble, which becomes readily soluble in alkali by the action of an acid. Resin. The term “alkali insoluble or alkali insoluble” as used herein refers to an alkali development condition employed when a resist pattern is formed from a resist film formed from a radiation sensitive resin composition containing the resin (A). When a film using only the resin (A) is developed in place of the resist film, it means that 50% or more of the initial film thickness of the film remains after development.

In the formula (1), A represents a single bond or a divalent linking group. The divalent linking group is preferably a divalent hydrocarbon group, and a divalent hydrocarbon group is preferably a chain or cyclic hydrocarbon group. Further, it may be an alkylene glycol group or an alkylene ester group. The chain or cyclic hydrocarbon group includes a methylene group, an ethylene group, a 1,3-propylene group or a 1,2-propylene group or other propylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, or a heptamethylene group. , Octamethylene group, nonamethylene group, decamethylene group, undecamethylene group, dodecamethylene group, tridecamethylene group, tetradecamethylene group, pentadecamethylene group, hexadecamethylene group, heptadecamethylene group, octadecamethylene group, Nonadecamethylene group, insalene group, 1-methyl-1,3-propylene group, 2-methyl-1,3-propylene group, 2-methyl-1,2-propylene group, 1-methyl-1,4-butylene group , 2-methyl-1,4-butylene group, methylidene group, ethylidene group, propylidene group, or Saturated chain hydrocarbon group such as 2-propylidene group, cyclobutylene group such as 1,3-cyclobutylene group, cyclopentylene group such as 1,3-cyclopentylene group, 1,4-cyclohexylene group, etc. A monocyclic hydrocarbon ring group such as a cycloalkylene group having 3 to 10 carbon atoms such as a cyclohexylene group, a cyclooctylene group such as a 1,5-cyclooctylene group, a 1,4-norbornylene group or a 2,5- Bridged cyclic carbonization such as a norbornylene group such as a norbornylene group, an adamantylene group such as a 1,5-adamantylene group, a 2,6-adamantylene group, or the like, or a hydrocarbon ring group having 4 to 30 carbon atoms. Examples include a hydrogen ring group.
Of the chain or cyclic hydrocarbon groups, preferred groups are a methylene group and an ethylene group.

In Formula (1), three X each independently represents an oxygen atom or a sulfur atom, and at least one X represents a sulfur atom. R ² represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alicyclic hydrocarbon group having 4 to 20 carbon atoms.
Examples of the linear or branched alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. Examples of the alicyclic hydrocarbon group having 4 to 20 carbon atoms include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, a norbornyl group, and an adamantyl group.

As a monomer which produces | generates a preferable repeating unit (1), following formula (1-1)-Formula (1-8) are mentioned. These monomers may be used alone or in combination of two or more.

式（２）において、Ｒ³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Ｒ³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Ｒ³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Ｒ³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。 The polymer of the present invention is preferably further copolymerized with a monomer having a side chain represented by the following formula (2). Hereinafter, a repeating unit obtained from a monomer having a side chain represented by the following formula (2) is referred to as “repeating unit (2)”.

In the formula (2), R ³ each independently represents a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or a linear or branched alkyl group having 1 to 4 carbon atoms. And at least one of R ³ is the alicyclic hydrocarbon group or a derivative thereof, or any two R ³ are bonded to each other, and together with the carbon atom to which each is bonded, 4 to 20 carbon atoms. A divalent alicyclic hydrocarbon group or a derivative thereof, and the remaining R ³ is a linear or branched alkyl group having 1 to 4 carbon atoms, or a monovalent alicyclic ring having 4 to 20 carbon atoms. Represents a hydrocarbon group or a derivative thereof.

In formula (2), R ³ monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms and divalent fat having 4 to 20 carbon atoms formed by bonding any two R ³ to each other. Examples of the cyclic hydrocarbon group include alicyclic rings derived from norbornane, tricyclodecane, tetracyclododecane, adamantane, cycloalkanes such as cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane. A group consisting of these alicyclic rings is, for example, a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t- Examples include a group substituted with one or more linear or branched or cyclic alkyl groups having 1 to 4 carbon atoms such as a butyl group. 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 ³ 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, an ethyl group, an n-propyl group, and an i-propyl group are preferable.

式（ａ）、式（ｂ）、式（ｃ）および式（ｄ）において、各Ｒ⁴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０〜４の整数である。
式（ａ）、式（ｂ）、式（ｃ）および式（ｄ）において、Ｒ⁴の炭素数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、ｎ−プロピル基、ｉ−プロピル基が好ましい。 As the skeleton contained in the preferred repeating unit (2), for example, a group represented by the following formula (a), formula (b), formula (c) or formula (d) is preferable.

In formula (a), formula (b), formula (c) and formula (d), each R ⁴ independently represents a linear or branched alkyl group having 1 to 4 carbon atoms, and m is 0. It is an integer of ~ 4.
In the formula (a), formula (b), formula (c) and formula (d), examples of the linear or branched alkyl group having 1 to ⁴ carbon atoms of R ⁴ include a methyl group, an ethyl group, Examples include n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group and the like. Of these alkyl groups, a methyl group, an ethyl group, an n-propyl group, and an i-propyl group are preferable.

As the group represented by the formula (a), a group in which two R ^{4 s} are both methyl groups is particularly preferable. In addition, the group represented by the formula (b) is particularly preferably a group in which R ⁴ is a methyl group, an ethyl group, an n-propyl group, or an i-propyl group. The group represented by the formula (c) is particularly a group in which m is 0 and R ⁴ is a methyl group, a group in which m is 0 and R ⁴ is an ethyl group, m is 1 and R ⁴ is methyl. A group which is a group and m is 1 and R4 is an ethyl group is preferable. As the group represented by the formula (d), a group in which two R ^{4 s} are both methyl groups is particularly preferable.

なお、繰り返し単位（２）の主鎖骨格は特に限定されるものではないが、好ましくは、メタクリル酸エステル、アクリル酸エステルあるいはαトリフルオロアクリル酸エステル構造を有する。また、明細書中、「（メタ）アクリル酸エステル」とはアクリル酸エステルおよびメタクリル酸エステルの双方を意味するものとする。 Examples of the skeleton contained in the repeating unit (2) other than the above include t-butoxycarbonyl group and groups represented by the following formulas (e-1) to (e-8).

The main chain skeleton of the repeating unit (2) is not particularly limited, but preferably has a methacrylic acid ester, acrylic acid ester or α-trifluoroacrylic acid ester structure. In the specification, “(meth) acrylic acid ester” means both acrylic acid ester and methacrylic acid ester.

Among the monomers giving the repeating unit (2), (meth) acrylic acid 2-methyladamantyl-2-yl ester and (meth) acrylic acid 2-methyl-3-hydroxyadamantyl-2-yl are preferable. Ester, (meth) acrylic acid 2-ethyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyl-3-hydroxyadamantyl-2-yl ester, (meth) acrylic acid 2-n-propyladamantyl-2-yl ester Yl ester, (meth) acrylic acid 2-isopropyladamantyl-2-yl ester, (meth) acrylic acid-2-methylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-2- Ethylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-8-methyltricyclo [5.2 1.0 ^2,6] decan-8-yl ester, (meth) ethyl-8-acrylic acid tricyclo [5.2.1.0 ^2,6] decan-8-yl ester, (meth) acrylic acid - 4-methyltetracyclo [6.2.1 ^3,6 . 0 ^2,7 ] dodecan-4-yl ester, (meth) acrylic acid-4-ethyltetracyclo [6.2.1 ^3,6 . 0 ^2,7 ] dodecan-4-yl ester, (meth) acrylic acid 1- (bicyclo [2.2.1] hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (tricyclo [5.2.1.0 ^2,6 ] decan-8-yl) -1-methylethyl ester, (meth) acrylic acid 1- (tetracyclo [6.2.1 ^3,6 .0 ^2,7 ] dodecane -4-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) acrylic acid 1- (3-hydroxyadamantan-1-yl) -1-methyl ethyl ester, (meth) acrylic acid 1,1-dicyclohexylethyl ester, (meth) acrylic acid 1,1-di (bicyclo [2.2.1] hept-2-yl) ethyl ester, (Meth) acrylic 1,1-di (tricyclo [5.2.1.0 ^2,6] decan-8-yl) ethyl ester, (meth) acrylic acid 1,1-di (tetracyclo [6.2.1 ^3,6. 0 ^2,7 ] dodecan-4-yl) ethyl ester, (meth) acrylic acid 1,1-di (adamantan-1-yl) ethyl ester, (meth) acrylic acid 1-methyl-1-cyclopentyl ester, (meth ) Acrylic acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, (meth) acrylic acid 1-ethyl-1-cyclohexyl ester, and the like.
Particularly suitable monomers include (meth) acrylic acid 2-methyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyladamantyl-2-yl ester, (meth) acrylic acid-2-methylbicyclo [ 2.2.1] Hept-2-yl ester, (meth) acrylic acid-2-ethylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid 1- (bicyclo [2.2 .1] Hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) acrylic acid 1-methyl-1-cyclopentyl ester (Meth) acrylic acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, (meth) acrylic acid 1- Chill-1-cyclohexyl ester.
Moreover, the polymer in this invention may contain 2 or more types of a repeating unit (2).

The polymer in the present invention may further contain one or more repeating units other than the repeating unit (1) and the repeating unit (2) (hereinafter referred to as “other repeating units”).
As other repeating units, repeating units having side chains represented by the following formulas (3-1) to (3-6) (hereinafter referred to as “other repeating units (3)”), formula (4) ) Represented by a repeating unit (hereinafter referred to as “other repeating unit (4)”), a repeating unit represented by formula (5) (hereinafter referred to as “other repeating unit (5)”), a formula It is preferable to contain at least one repeating unit selected from the repeating units represented by (6) (hereinafter referred to as “other repeating units (6)”).

式（３−１）〜式（３−６）の各式において、Ｒ⁵は水素原子または炭素数１〜４の置換基を有してもよいアルキル基を示し、Ｒ⁶は水素原子またはメトキシ基を表す。Ａ’は単結合またはメチレン基を表し、Ｂは酸素原子またはメチレン基を表す。ｌは１〜３の整数を示し、ｍ’は０または１である。
また、上記他の繰り返し単位（３）の主鎖骨格は特に限定されるものではないが、好ましくは、メタクリル酸エステル、アクリル酸エステルあるいはαトリフルオロアクリル酸エステル構造を有する。

In the formulas (3-1) to (3-6), R ⁵ represents a hydrogen atom or an alkyl group which may have a substituent having 1 to 4 carbon atoms, and R ⁶ represents a hydrogen atom or methoxy. Represents a group. A ′ represents a single bond or a methylene group, and B represents an oxygen atom or a methylene group. l represents an integer of 1 to 3, and m ′ is 0 or 1.
The main chain skeleton of the other repeating unit (3) is not particularly limited, but preferably has a methacrylic acid ester, acrylic acid ester or α-trifluoroacrylic acid ester structure.

Among the monomers that give the repeating unit (3), (meth) acrylic acid-5-oxo-4-oxatricyclo [4.2.1.0 ^3,7 ] noner-2-yl ester is preferable. (Meth) acrylic acid-9-methoxycarbonyl-5-oxo-4-oxatricyclo [4.2.1.0 ^3,7 ] noner 2-yl ester, (meth) acrylic acid-5-oxo-4-oxy Sertricyclo [5.2.1.0 ^3,8 ] deca-2-yl ester, (meth) acrylic acid-10-methoxycarbonyl-5-oxo-4-oxatricyclo [5.2.1.0 ^{3 , 8} ] Noner 2-yl ester, (meth) acrylic acid-6-oxo-7-oxabicyclo [3.2.1] oct-2-yl ester, (meth) acrylic acid-4-methoxycarbonyl-6-oxo- 7-Oxabivy B [3.2.1] oct-2-yl ester, (meth) acrylic acid-7-oxo-8-oxabicyclo [3.3.1] oct-2-yl ester, (meth) acrylic acid-4-methoxy Carbonyl-7-oxo-8-oxabicyclo [3.3.1] oct-2-yl ester, (meth) acrylic acid-2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-4-methyl-2 -Oxotetrahydropyran-4-yl ester, (meth) acrylic acid-4-ethyl-2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-4-propyl-2-oxotetrahydropyran-4-yl ester, (Meth) acrylic acid-5-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-2,2-dimethyl- 5-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-4,4-dimethyl-5-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-2-oxotetrahydrofuran-3-yl ester, (meth ) Acrylic acid-4,4-dimethyl-2-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-5,5-dimethyl-2-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-2-oxotetrahydrofura N-yl ester, (meth) acrylic acid-5-oxotetrahydrofuran-2-ylmethyl ester, (meth) acrylic acid-3,3-dimethyl-5-oxotetrahydrofuran-2-ylmethyl ester, (meth) acrylic acid -4,4-Dimethyl-5-oxotetrahydride Furan-2-yl methyl ester.

式（４）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、Ｚは炭素数７〜２０の多環型脂環式炭化水素基であり、この炭素数７〜２０の多環型脂環式炭化水素基は、炭素数１〜４のアルキル基、ヒドロキシル基、シアノ基、炭素数１〜１０のヒドロキシアルキル基で置換されていても、置換されていなくてもよい。
好ましいＺとしては、例えば、下記式に示すように、ビシクロ［２．２．１］ヘプタン（４ａ）、ビシクロ［２．２．２］オクタン（４ｂ）、トリシクロ［５．２．１．０^2,6］デカン（４ｃ）、テトラシクロ［６．２．１．１^3,6．０^2,7］ドデカン（４ｄ）、トリシクロ［３．３．１．１^3,7］デカン（４ｅ）等のシクロアルカン類に由来する脂環族環からなる炭化水素基が挙げられる。

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個以上で置換してもよい。また、これらの他の繰り返し単位（４）は１種または２種以上を含有することができる。 Another repeating unit (4) is represented by the following formula (4).

In the formula (4), R ⁷ represents a hydrogen atom, a methyl group, or a trifluoromethyl group, Z is a polycyclic alicyclic hydrocarbon group having 7 to 20 carbon atoms, and this 7 to 20 carbon atoms. The polycyclic alicyclic hydrocarbon group may or may not be substituted with an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, a cyano group, or a hydroxyalkyl group having 1 to 10 carbon atoms.
Preferred examples of Z include bicyclo [2.2.1] heptane (4a), bicyclo [2.2.2] octane (4b), and tricyclo [5.2.1.0 ² , as shown in the following formula. ^{, 6} ] decane (4c), tetracyclo [6.2.1.1 ^3,6 . Hydrocarbon groups composed of alicyclic rings derived from cycloalkanes such as 0 ^2,7 ] dodecane (4d) and tricyclo [3.3.1.1 ^3,7 ] decane (4e).

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. , 1-methylpropyl group, t-butyl group and the like, or a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms may be substituted with one or more. Moreover, these other repeating units (4) can contain 1 type (s) or 2 or more types.

Among the monomers giving other repeating units (4), (meth) acrylic acid-bicyclo [2.2.1] heptyl ester, (meth) acrylic acid-cyclohexyl ester, (meth) acrylic acid are preferred. -Bicyclo [4.4.0] decanyl ester, (meth) acrylic acid-bicyclo [2.2.2] octyl ester, (meth) acrylic acid-tricyclo [5.2.1.0 ^2,6 ] deca Nyl ester, (meth) acrylic acid-tetracyclo [6.2.1.1 ^3,6 . ^0,7 ] dodecanyl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] decanyl ester, and the like.

式（５）において、Ｒ⁸は水素原子、炭素数１〜４のアルキル基、トリフルオロメチル基、またはヒドロキシメチル基を表し、Ｒ⁹は、２価の有機基を表す。
Ｒ⁹としての２価の有機基は、好ましくは２価の炭化水素基であり、２価の炭化水素基の中でも好ましくは鎖状または環状の炭化水素基が好ましく、アルキレングリコール基、アルキレンエステル基であってもよい。
好ましいＲ⁹としては、メチレン基、エチレン基、１，３−プロピレン基もしくは１，２−プロピレン基などのプロピレン基、テトラメチレン基、ペンタメチレン基、ヘキサメチレン基、ヘプタメチレン基、オクタメチレン基、ノナメチレン基、デカメチレン基、ウンデカメチレン基、ドデカメチレン基、トリデカメチレン基、テトラデカメチレン基、ペンタデカメチレン基、ヘキサデカメチレン基、ヘプタデカメチレン基、オクタデカメチレン基、ノナデカメチレン基、インサレン基、１−メチル−１，３−プロピレン基、２−メチル１，３−プロピレン基、２−メチル−１，２−プロピレン基、１−メチル−１，４−ブチレン基、２−メチル−１，４−ブチレン基、メチリデン基、エチリデン基、プロピリデン基、または、２−プロピリデン基等の飽和鎖状炭化水素基、１，３−シクロブチレン基などのシクロブチレン基、１，３−シクロペンチレン基などのシクロペンチレン基、１，４−シクロヘキシレン基などのシクロヘキシレン基、１，５−シクロオクチレン基などのシクロオクチレン基等の炭素数３〜１０のシクロアルキレン基などの単環式炭化水素環基、１，４−ノルボルニレン基もしくは２，５−ノルボルニレン基などのノルボルニレン基、１，５−アダマンチレン基、２，６−アダマンチレン基などのアダマンチレン基等の２〜４環式炭素数４〜３０の炭化水素環基などの架橋環式炭化水素環基等が挙げられる。 Another repeating unit (5) is represented by the following formula (5).

In Formula (5), R ⁸ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a trifluoromethyl group, or a hydroxymethyl group, and R ⁹ represents a divalent organic group.
The divalent organic group as R ⁹ is preferably a divalent hydrocarbon group, and among the divalent hydrocarbon groups, a chain or cyclic hydrocarbon group is preferable, an alkylene glycol group, an alkylene ester group It may be.
Preferred R ⁹ is a methylene group, an ethylene group, a propylene group such as a 1,3-propylene group or a 1,2-propylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group, Nonamethylene group, Decamemethylene group, Undecamethylene group, Dodecamethylene group, Tridecamethylene group, Tetradecamethylene group, Pentadecamethylene group, Hexadecamethylene group, Heptadecamethylene group, Octadecamethylene group, Nonadecamethylene group, Insalen group, 1-methyl-1,3-propylene group, 2-methyl-1,3-propylene group, 2-methyl-1,2-propylene group, 1-methyl-1,4-butylene group, 2-methyl- 1,4-butylene group, methylidene group, ethylidene group, propylidene group, or 2-propylidene group Saturated chain hydrocarbon groups such as ethylene groups, cyclobutylene groups such as 1,3-cyclobutylene groups, cyclopentylene groups such as 1,3-cyclopentylene groups, and cyclohexylenes such as 1,4-cyclohexylene groups Group, monocyclic hydrocarbon ring group such as cycloalkylene group having 3 to 10 carbon atoms such as cyclooctylene group such as 1,5-cyclooctylene group, 1,4-norbornylene group or 2,5-norbornylene group Such as norbornylene group, 1,5-adamantylene group, adamantylene group such as 2,6-adamantylene group, etc., bridged cyclic hydrocarbon ring such as 2-4 cyclic hydrocarbon ring group having 4-30 carbon atoms Groups and the like.

Particularly when R ⁹ contains a divalent aliphatic cyclic hydrocarbon group, an alkylene group having 1 to 4 carbon atoms is inserted as a spacer between the bistrifluoromethyl-hydroxy-methyl group and the aliphatic cyclic hydrocarbon group. It is preferable to do.
R ⁹ is preferably a hydrocarbon group containing a 2,5-norbornylene group, a 1,2-ethylene group, or a propylene group.

Among the monomers giving other repeating units (5), (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-3-propyl) ester is preferable. , (Meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-butyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-tri Fluoromethyl-2-hydroxy-5-pentyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester, (meth) acrylic acid 2 -{[5- (1 ', 1', 1'-trifluoro-2'-trifluoromethyl-2'-hydroxy) propyl] bicyclo [2.2.1] heptyl} ester, (meth) a Acrylic acid 3 - {[8- (1 ', 1', 1'-trifluoro-2'-trifluoromethyl-2'-hydroxy) propyl] tetracyclo [6.2.1.1 ^{3, 6.} 0 ^2,7 ] dodecyl} ester and the like.

式（６）において、Ｒ¹⁰は水素原子またはメチル基を表し、Ｘ’は単結合または炭素数１〜３の２価の有機基を表し、Ｙは相互に独立に単結合または炭素数１〜３の２価の有機基を表す。Ｘ’およびＹで表される炭素数１〜３の２価の有機基としては、メチレン基、エチレン基、プロピレン基が挙げられる。Ｒ¹¹は相互に独立に水素原子、水酸基、シアノ基、またはＣＯＯＲ¹²基を表す。ただし、Ｒ¹²は水素原子あるいは炭素数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３〜２０の脂環式のアルキル基を表す。なお、３つのＲ¹¹のうち少なくとも１つは水素原子でなく、かつＸ’が単結合のときは、３つのＹのうち少なくとも１つは炭素数１〜３の２価の有機基であることが好ましい。
Ｒ¹²における、上記炭素数１〜４の直鎖状もしくは分岐状のアルキル基としては、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−ブチル基を例示できる。また、上記炭素数３〜２０の脂環式のアルキル基としては、−Ｃ_nＨ_2n-1（ｎは３〜２０の整数）で表されるシクロアルキル基、例えば、シクロプロピル基、シクロブチル基、シクロペンチル基、シクロヘキシル基、シクロヘプチル基、シクロオクチル基等が、また、多環型脂環式アルキル基、例えばビシクロ［２．２．１］ヘプチル基、トリシクロ［５．２．１．０^2,6］デシル基、テトラシクロ［６．２．１^3,6．０^2,7］ドデカニル基、アダマンチル基等、または、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個以上でシクロアルキル基または多環型脂環式アルキル基の一部を置換した基等が挙げられる。 Another repeating unit (6) is represented by the following formula (6).

In Formula (6), R ¹⁰ represents a hydrogen atom or a methyl group, X ′ represents a single bond or a divalent organic group having 1 to 3 carbon atoms, and Y is independently a single bond or 1 to 1 carbon atoms. 3 represents a divalent organic group. Examples of the divalent organic group having 1 to 3 carbon atoms represented by X ′ and Y include a methylene group, an ethylene group, and a propylene group. R ¹¹ independently represents a hydrogen atom, a hydroxyl group, a cyano group, or a COOR ¹² group. R ¹² represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alicyclic alkyl group having 3 to 20 carbon atoms. When at least one of the three R ¹¹ is not a hydrogen atom and X ′ is a single bond, at least one of the three Y is a divalent organic group having 1 to 3 carbon atoms. Is preferred.
Examples of the linear or branched alkyl group having 1 to 4 carbon atoms in R ¹² include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, Examples thereof include a 1-methylpropyl group and a t-butyl group. Examples of the alicyclic alkyl groups of said 3 to 20 carbon atoms, -C _n H _2n-1 cycloalkyl group (n is an integer of 3 to 20) represented by, for example, cyclopropyl group, cyclobutyl group , A cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, etc., and a polycyclic alicyclic alkyl group such as a bicyclo [2.2.1] heptyl group, a tricyclo [5.2.1.0 ^{2]. , 6} ] decyl group, tetracyclo [6.2.1 ^3,6 . 0 ^2,7 ] a dodecanyl group, an adamantyl group or the like, or one or more linear, branched or cyclic alkyl groups and a part of a cycloalkyl group or a polycyclic alicyclic alkyl group. Examples include substituted groups.

  Among the monomers giving the repeating unit (6), preferred monomers are (meth) acrylic acid 3-hydroxyadamantan-1-ylmethyl ester, (meth) acrylic acid 3,5-dihydroxyadamantane-1- Ylmethyl ester, (meth) acrylic acid 3-hydroxy-5-methyladamantan-1-yl ester, (meth) acrylic acid 3,5-dihydroxy-7-methyladamantan-1-yl ester, (meth) acrylic acid 3 -Hydroxy-5,7-dimethyladamantan-1-yl ester, (meth) acrylic acid 3-hydroxy-5,7-dimethyladamantan-1-ylmethyl ester, and the like.

  As repeating units other than the above formulas (1) to (6), for example, (meth) acrylic acid esters having a bridged hydrocarbon skeleton such as dicyclopentenyl (meth) acrylate and adamantylmethyl (meth) acrylate Carboxyl group having a bridged hydrocarbon skeleton of unsaturated carboxylic acid such as carboxynorbornyl (meth) acrylate, carboxytricyclodecanyl (meth) acrylate, carboxytetracycloundecanyl (meth) acrylate Containing esters;

Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, 2-methylpropyl (meth) acrylate, 1-methyl (meth) acrylate Propyl, t-butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, cyclopropyl (meth) acrylate, ( (Meth) acrylic acid cyclopentyl, (meth) acrylic acid cyclohexyl, (meth) acrylic acid 4-methoxycyclohexyl, (meth) acrylic acid 2-cyclopentyloxycarbonylethyl, (meth) acrylic acid 2-cyclohexyloxycarbonylethyl, (meth) 2- (4-Methoxycyclohexyl) acrylic acid No bridged hydrocarbon skeleton such as aryloxycarbonyl ethyl (meth) acrylate;

α-hydroxymethyl acrylate esters such as methyl α-hydroxymethyl acrylate, ethyl α-hydroxymethyl acrylate, n-propyl α-hydroxymethyl acrylate, n-butyl α-hydroxymethyl acrylate; (meth) acrylonitrile , Α-chloroacrylonitrile, crotonnitrile, maleinonitrile, fumaronitrile, mesaconitrile, citraconitrile, itaconnitrile, and other unsaturated nitrile compounds; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, crotonamide, maleinamide , Fumaramide, mesaconamide, citraconic amide, itaconic amide, etc .; N- (meth) acryloylmorpholine, N-vinyl-ε-caprolactam, N-vinylpyrrolidone, vinyl Other nitrogen-containing vinyl compounds such as lysine and vinylimidazole; (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, etc. Unsaturated carboxylic acids (anhydrides); 2-carboxyethyl (meth) acrylate, 2-carboxypropyl (meth) acrylate, 3-carboxypropyl (meth) acrylate, 4-carboxybutyl (meth) acrylate, Carboxyl group-containing esters having no bridged hydrocarbon skeleton of unsaturated carboxylic acid such as (meth) acrylic acid 4-carboxycyclohexyl;

1,2-adamantanediol di (meth) acrylate, 1,3-adamantanediol di (meth) acrylate, 1,4-adamantanediol di (meth) acrylate, tricyclodecanyl dimethylol di (meth) acrylate, etc. A polyfunctional monomer having a bridged hydrocarbon skeleton;

Methylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 2,5-dimethyl-2,5-hexanediol di ( (Meth) acrylate, 1,8-octanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,4-bis (2-hydroxypropyl) benzenedi (meth) acrylate, 1,3-bis List units in which a polymerizable unsaturated bond of a polyfunctional monomer such as a polyfunctional monomer having no bridged hydrocarbon skeleton such as (2-hydroxypropyl) benzenedi (meth) acrylate is cleaved Can do.
Among these repeating units other than the above formulas (1) to (6), a unit in which a polymerizable unsaturated bond of (meth) acrylic acid ester having a bridged hydrocarbon skeleton is cleaved is preferable.

  In the polymer of the present invention, the content of the repeating unit (1) is usually 10 to 90 mol%, preferably 10 to 80 mol%, more preferably 20 to 80 mol%, based on all repeating units. . In this case, if the content of the repeating unit (1) is less than 10 mol%, a sufficient refractive index cannot be provided at 193 nm, while if it exceeds 90 mol%, the resolution as a resist may deteriorate. is there.

  Moreover, the content rate of a repeating unit (2) is 10-90 mol% normally with respect to all the repeating units, Preferably it is 10-80 mol%, More preferably, it is 20-70 mol%. In this case, if the content of the repeating unit (2) is less than 10 mol%, the resolution as a resist may be deteriorated. On the other hand, if it exceeds 90 mol%, the developability of the resist may be deteriorated.

  Moreover, the content rate of a repeating unit (3) is 10-70 mol% normally with respect to all the repeating units, Preferably it is 15-65 mol%, More preferably, it is 20-60 mol%. In this case, if the content of the repeating unit (3) is less than 10 mol%, the resist may have poor solubility in an alkaline developer, which may contribute to development defects or deteriorate the exposure margin. is there. The exposure margin indicates a change in line width with respect to a change in exposure amount. On the other hand, if it exceeds 70 mol%, the solubility of the resist in the solvent is lowered, and the resolution may be lowered.

  Moreover, the content rate of a repeating unit (4) is 30 mol% or less normally with respect to all the repeating units, Preferably it is 25 mol% or less. In this case, if the content of the repeating unit (4) exceeds 30 mol%, the resulting resist film may be easily swollen by the alkali developer or the solubility in the alkali developer may be reduced.

  Moreover, the content rate of a repeating unit (5) is 30 mol% or less normally with respect to all the repeating units, Preferably it is 25 mol% or less. In this case, if the content of the repeating unit (5) exceeds 30 mol%, the top loss of the resist pattern may occur and the pattern shape may be deteriorated.

  Moreover, the content rate of a repeating unit (6) is 30 mol% or less normally with respect to all the repeating units, Preferably it is 25 mol% or less. In this case, if the content of the repeating unit (6) exceeds 30 mol%, the resulting resist film may be easily swollen by the alkali developer or the solubility in the alkali developer may be reduced.

  Furthermore, the content of other repeating units is usually 50 mol% or less, preferably 40 mol% or less, based on all repeating units.

  The polymer of the present invention, for example, a polymerizable unsaturated monomer corresponding to each repeating unit is used with 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 alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cyclohexane, cycloheptane, cyclooctane, decalin, Cycloalkanes such as norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene; halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene; ethyl acetate Saturated carboxylic acid esters such as n-butyl acetate, i-butyl acetate and methyl propionate; ketones such as acetone, 2-butanone, 4-methyl-2-pentanone and 2-heptanone; tetrahydrofuran, dimethoxyethanes, Ethers such as diethoxyethanes It can be mentioned. These solvents can be used alone or in admixture of two or more. Moreover, the reaction temperature in the said superposition | polymerization is 40-150 degreeC normally, Preferably it is 50-120 degreeC, and reaction time is 1-48 hours normally, Preferably it is 1-24 hours.

  The polystyrene-reduced mass average molecular weight (hereinafter referred to as “Mw”) of the polymer in the present invention by gel permeation chromatography (GPC) is not particularly limited, but is preferably 1,000 to 100,000, more preferably 1, 000 to 30,000, more preferably 1,000 to 20,000. In this case, if the Mw of the polymer is less than 1,000, the heat resistance when used as a resist tends to decrease, while if it exceeds 100,000, the developability when used as a resist tends to decrease. The ratio (Mw / Mn) of the polymer Mw to the polystyrene-reduced number average molecular weight (hereinafter referred to as “Mn”) by gel permeation chromatography (GPC) is usually 1 to 5, preferably 1 to 3. It is.

The polymer of the present invention is such that the content of the low molecular weight component derived from the monomer used when preparing the resin (A) from the polymer is 100% by mass in terms of solid content. It is preferable that it is 0.1 mass% or less, More preferably, it is 0.07 mass% or less, More preferably, it is 0.05 mass% or less. When this content is 0.1% by mass or less, it is possible to reduce the amount of the eluate in water that is in contact with the immersion exposure. Furthermore, foreign matters are not generated in the resist during resist storage, and coating unevenness does not occur during resist application, and the occurrence of defects during resist pattern formation can be sufficiently suppressed.
Examples of the low molecular weight component derived from the monomer include a monomer, a dimer, a trimer, and an oligomer, and can be a component having an Mw of 500 or less. The components having an Mw of 500 or less can be removed by, for example, chemical purification methods such as washing with water and liquid-liquid extraction, or a combination of these chemical purification methods and physical purification methods such as ultrafiltration and centrifugation. it can. Moreover, it can analyze by the high performance liquid chromatography (HPLC) of resin.
The resin (A) is preferably as less as possible for impurities such as halogen and metal, whereby sensitivity, resolution, process stability, pattern shape and the like can be further improved. Examples of the purification method of the resin (A) include chemical purification methods such as washing with water and liquid-liquid extraction, and combinations of these chemical purification methods with physical purification methods such as ultrafiltration and centrifugation, etc. Can be mentioned. In this invention, resin (A) can be used individually or in mixture of 2 or more types.

Radiation sensitive acid generator (B)
The photoacid generator used in the present embodiment comprises a radiation sensitive acid generator (hereinafter simply referred to as “acid generator”) that generates an acid upon exposure. The acid generator dissociates the acid dissociable group in the repeating unit present in the copolymer by the action of the acid generated by exposure (eliminates the protecting group), and as a result, the exposed portion of the resist film becomes alkaline. It becomes readily soluble in a developer and has a function of forming a positive resist pattern. As an acid generator in this embodiment, what contains the compound (henceforth "the acid generator 1") represented by following formula (7) is preferable.

式（７）において、Ｒ¹³は水素原子、フッ素原子、水酸基、炭素原子数１〜１０の直鎖状もしくは分岐状のアルキル基、炭素原子数１〜１０の直鎖状もしくは分岐状のアルコキシル基、炭素原子数２〜１１の直鎖状もしくは分岐状のアルコキシカルボニル基を示し、Ｒ¹⁴は炭素原子数１〜１０の直鎖状もしくは分岐状のアルキル基、アルコキシル基もしくは炭素原子数１〜１０の直鎖状、分岐状、環状のアルカンスルホニル基を示し、Ｒ¹⁵は独立に炭素原子数１〜１０の直鎖状もしくは分岐状のアルキル基、置換されていてもよいフェニル基または置換基されていてもよいナフチル基を示すか、あるいは２個のＲ¹⁵が互いに結合して炭素原子数２〜１０の２価の基を形成しており、該２価の基は置換されていてもよく、ｋは０〜２の整数であり、Ｘ^-は式：Ｒ¹⁶Ｃ_nＦ_2nＳＯ^3-（式中、Ｒ¹⁶は、フッ素原子または置換されていてもよい炭素原子数１〜１２の炭化水素基を示し、ｎは１〜１０の整数である）で表されるアニオン、Ｒ¹⁶ＳＯ^3-で表されるアニオン、または下記式（８−１）、式（８−２）で表されるアニオンを表し、ｒは０〜１０の整数である。）

式（８−１）および式（８−２）において、Ｒ¹⁷は独立に炭素原子数１〜１０の直鎖状もしくは分岐状のフッ素原子を含有するアルキル基を表すか、あるいは２個のＲ¹⁷が互いに結合して炭素原子数２〜１０の２価のフッ素原子を含有する基を形成しており、該２価の基は置換されていてもよい。

In the formula (7), R ¹³ is a hydrogen atom, a fluorine atom, a hydroxyl group, a linear or branched alkyl group having 1 to 10 carbon atoms, or a linear or branched alkoxyl group having 1 to 10 carbon atoms. Represents a linear or branched alkoxycarbonyl group having 2 to 11 carbon atoms, and R ¹⁴ is a linear or branched alkyl group having 1 to 10 carbon atoms, an alkoxyl group, or an alkyl group having 1 to 10 carbon atoms. R ¹⁵ is independently a linear or branched alkyl group having 1 to 10 carbon atoms, an optionally substituted phenyl group or a substituted group. An naphthyl group which may be substituted, or two R ¹⁵ 's bonded to each other to form a divalent group having 2 to 10 carbon atoms, and the divalent group may be substituted. , K is an integer from 0 to 2 , X ^- is the formula: in _{^{R 16 C n F 2n SO 3-}} ( wherein, R ¹⁶ represents a fluorine atom or an optionally substituted hydrocarbon group having 1 to 12 carbon atoms, n represents 1 to 10 An anion represented by R ¹⁶ SO ^3- , or an anion represented by the following formula (8-1) or formula (8-2), and r is 0-10. Is an integer. )

In the formula (8-1) and the formula (8-2), R ¹⁷ independently represents an alkyl group containing a linear or branched fluorine atom having 1 to 10 carbon atoms, or two R ¹⁷ are bonded to each other to form a group containing a divalent fluorine atom having 2 to 10 carbon atoms, and the divalent group may be substituted.

In the formula (7), examples of the linear or branched alkyl group having 1 to 10 carbon atoms represented by R ¹³ , R ¹⁴ and R ¹⁵ include a methyl group, an ethyl group, an n-propyl group, and i-propyl. Group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group, n-pentyl group, neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl Group, n-nonyl group, n-decyl group and the like. Of these alkyl groups, a methyl group, an ethyl group, an n-butyl group, a t-butyl group, and the like are preferable.

Examples of the linear or branched alkoxyl group having 1 to 10 carbon atoms of R ¹³ and R ¹⁴ include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, 2-methylpropoxy group, 1-methylpropoxy group, t-butoxy group, n-pentyloxy group, neopentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, 2-ethylhexyloxy Group, n-nonyloxy group, n-decyloxy group and the like. Of these alkoxyl groups, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, and the like are preferable.

Examples of the linear or branched alkoxycarbonyl group having 2 to 11 carbon atoms represented by R ¹³ include, for example, a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an i-propoxycarbonyl group, and n-butoxy. Carbonyl group, 2-methylpropoxycarbonyl group, 1-methylpropoxycarbonyl group, t-butoxycarbonyl group, n-pentyloxycarbonyl group, neopentyloxycarbonyl group, n-hexyloxycarbonyl group, n-heptyloxycarbonyl group, An n-octyloxycarbonyl group, a 2-ethylhexyloxycarbonyl group, an n-nonyloxycarbonyl group, an n-decyloxycarbonyl group, and the like can be given. Of these alkoxycarbonyl groups, a methoxycarbonyl group, an ethoxycarbonyl group, an n-butoxycarbonyl group, and the like are preferable.

Examples of the linear, branched or cyclic alkanesulfonyl group having 1 to 10 carbon atoms of R ¹⁴ include a methanesulfonyl group, ethanesulfonyl group, n-propanesulfonyl group, n-butanesulfonyl group, tert. -Butanesulfonyl group, n-pentanesulfonyl group, neopentanesulfonyl group, n-hexanesulfonyl group, n-heptanesulfonyl group, n-octanesulfonyl group, 2-ethylhexanesulfonyl group n-nonanesulfonyl group, n-decanesulfonyl Group, cyclopentanesulfonyl group, cyclohexanesulfonyl group and the like. Of these alkanesulfonyl groups, a methanesulfonyl group, an ethanesulfonyl group, an n-propanesulfonyl group, an n-butanesulfonyl group, a cyclopentanesulfonyl group, a cyclohexanesulfonyl group, and the like are preferable.
Moreover, as r, 0-2 are preferable.

In the formula (7), examples of the optionally substituted phenyl group for R ¹⁵ include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 2,3-dimethylphenyl group, 2, 4-dimethylphenyl group, 2,5-dimethylphenyl group, 2,6-dimethylphenyl group, 3,4-dimethylphenyl group, 3,5-dimethylphenyl group, 2,4,6-trimethylphenyl group, 4- Substituted with phenyl groups such as ethylphenyl group, 4-t-butylphenyl group, 4-cyclohexylphenyl group, 4-fluorophenyl group or linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms Phenyl group; these phenyl group or alkyl-substituted phenyl group can be substituted with hydroxyl group, carboxyl group, cyano group, nitro group, alkoxyl group, alkoxyalkyl group. , It may be mentioned alkoxycarbonyl group, group obtained by substituting at least one group of one or more such alkoxycarbonyloxy group.

Among the substituents for the phenyl group and the alkyl-substituted phenyl group, examples of the alkoxyl group include methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, 2-methylpropoxy group, 1- Examples thereof include a linear, branched or cyclic alkoxyl group having 1 to 20 carbon atoms such as a methylpropoxy group, a t-butoxy group, a cyclopentyloxy group and a cyclohexyloxy group.
Examples of the alkoxyalkyl group include 2 to 21 carbon atoms such as a methoxymethyl group, an ethoxymethyl group, a 1-methoxyethyl group, a 2-methoxyethyl group, a 1-ethoxyethyl group, and a 2-ethoxyethyl group. And linear, branched or cyclic alkoxyalkyl groups. Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an i-propoxycarbonyl group, an n-butoxycarbonyl group, a 2-methylpropoxycarbonyl group, and a 1-methylpropoxycarbonyl group. , T-butoxycarbonyl group, cyclopentyloxycarbonyl group, cyclohexyloxycarbonyl and the like, which are linear, branched or cyclic alkoxycarbonyl groups having 2 to 21 carbon atoms.

Examples of the alkoxycarbonyloxy group include methoxycarbonyloxy group, ethoxycarbonyloxy group, n-propoxycarbonyloxy group, i-propoxycarbonyloxy group, n-butoxycarbonyloxy group, t-butoxycarbonyloxy group, Examples thereof include linear, branched or cyclic alkoxycarbonyloxy groups having 2 to 21 carbon atoms such as cyclopentyloxycarbonyl group and cyclohexyloxycarbonyl.
Examples of the optionally substituted phenyl group represented by R ¹⁵ in the formula (7) include a phenyl group, a 4-cyclohexylphenyl group, a 4-t-butylphenyl group, a 4-methoxyphenyl group, and a 4-t-butoxyphenyl group. Is preferred.

Examples of the optionally substituted naphthyl group for R ¹⁵ include 1-naphthyl group, 2-methyl-1-naphthyl group, 3-methyl-1-naphthyl group, 4-methyl-1-naphthyl group, 4-methyl-1-naphthyl group, 5-methyl-1-naphthyl group, 6-methyl-1-naphthyl group, 7-methyl-1-naphthyl group, 8-methyl-1-naphthyl group, 2,3-dimethyl -1-naphthyl group, 2,4-dimethyl-1-naphthyl group, 2,5-dimethyl-1-naphthyl group, 2,6-dimethyl-1-naphthyl group, 2,7-dimethyl-1-naphthyl group, 2,8-dimethyl-1-naphthyl group, 3,4-dimethyl-1-naphthyl group, 3,5-dimethyl-1-naphthyl group, 3,6-dimethyl-1-naphthyl group, 3,7-dimethyl- 1-naphthyl group, 3,8-dimethyl-1-naphth Group, 4,5-dimethyl-1-naphthyl group, 5,8-dimethyl-1-naphthyl group, 4-ethyl-1-naphthyl group, 2-naphthyl group, 1-methyl-2-naphthyl group, 3-methyl A naphthyl group substituted with a naphthyl group such as a 2-naphthyl group or 4-methyl-2-naphthyl group or a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms; these naphthyl group or alkyl Examples include a group in which a substituted naphthyl group is substituted with at least one group such as a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an alkoxyl group, an alkoxyalkyl group, an alkoxycarbonyl group, and an alkoxycarbonyloxy group. Can do.

Examples of the alkoxyl group, alkoxyalkyl group, alkoxycarbonyl group, and alkoxycarbonyloxy group that are the substituents include the groups exemplified for the phenyl group and the alkyl-substituted phenyl group. Examples of the optionally substituted naphthyl group of R ¹⁵ in the formula (7) include 1-naphthyl group, 1- (4-methoxynaphthyl) group, 1- (4-ethoxynaphthyl) group, 1- (4-n -Propoxynaphthyl) group, 1- (4-n-butoxynaphthyl) group, 2- (7-methoxynaphthyl) group, 2- (7-ethoxynaphthyl) group, 2- (7-n-propoxynaphthyl) group, A 2- (7-n-butoxynaphthyl) group and the like are preferable.

In addition, the divalent group having 2 to 10 carbon atoms formed by bonding two R ¹⁵ to each other is preferably a 5- or 6-membered ring, particularly preferably a 5-membered ring, together with the sulfur atom in the formula (7). A group that forms a ring (that is, a tetrahydrothiophene ring) is desirable. Examples of the substituent for the divalent group include a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an alkoxyl group, an alkoxyalkyl group, an alkoxy group exemplified as the substituent for the phenyl group and the alkyl-substituted phenyl group. Examples thereof include a carbonyl group and an alkoxycarbonyloxy group.
As R ¹⁵ in the formula (7), a methyl group, an ethyl group, a phenyl group, a 4-methoxyphenyl group, a 1-naphthyl group, and two R ¹⁵ are bonded to each other to form a tetrahydrothiophene ring structure together with a sulfur atom. A divalent group or the like is preferable.

  Preferred cation sites of formula (7) include triphenylsulfonium cation, tri-1-naphthylsulfonium cation, tri-tert-butylphenylsulfonium cation, 4-fluorophenyl-diphenylsulfonium cation, di-4-fluorophenyl-phenyl. Sulfonium cation, tri-4-fluorophenylsulfonium cation, 4-cyclohexylphenyl-diphenylsulfonium cation, 4-methanesulfonylphenyl-diphenylsulfonium cation, 4-cyclohexanesulfonyl-diphenylsulfonium cation, 1-naphthyldimethylsulfonium cation, 1-naphthyl Diethylsulfonium cation, 1- (4-hydroxynaphthyl) dimethylsulfonium cation, 1- (4-methyl) Naphthyl) dimethylsulfonium cation, 1- (4-methylnaphthyl) diethylsulfonium cation, 1- (4-cyanonaphthyl) dimethylsulfonium cation, 1- (4-cyanonaphthyl) diethylsulfonium cation, 1- (3,5-dimethyl -4-hydroxyphenyl) tetrahydrothiophenium cation, 1- (4-methoxynaphthyl) tetrahydrothiophenium cation, 1- (4-ethoxynaphthyl) tetrahydrothiophenium cation, 1- (4-n-propoxynaphthyl) Tetrahydrothiophenium cation, 1- (4-n-butoxynaphthyl) tetrahydrothiophenium cation, 2- (7-methoxynaphthyl) tetrahydrothiophenium cation, 2- (7-ethoxynaphthyl) tetrahydrothi Fe cation, 2- (7-n- propoxy-naphthyl) tetrahydrothiophenium cation, 2- (7-n- butoxynaphthyl) tetrahydrothiophenium cation, and the like.

C _n F _2n with R ¹⁶ in C _n F _2n SO ^3- anions represented in - ^- X of formula (7) group is a perfluoroalkylene group having a carbon number n, said group linear Or it can be branched. Here, n is preferably 1, 2, 4 or 8. Examples of the optionally substituted hydrocarbon group having 1 to 12 carbon atoms for R ¹⁶ in R ¹⁶ C _n F _2n SO ^3- and R ¹⁶ SO ³ -anions include an alkyl group having 1 to 12 carbon atoms, cyclo An alkyl group and a bridged alicyclic hydrocarbon group are preferred. Specifically, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group, n-pentyl group, neopentyl group N-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, norbornyl group, norbornylmethyl group, hydroxynorbornyl group, adamantyl group Etc.

The alkyl group containing a linear or branched fluorine atom having 1 to 10 carbon atoms independently represented by R ¹⁷ in formula (8-1) and formula (8-2) is a trifluoromethyl group or pentafluoroethyl. Group, heptafluoropropyl group, nonafluorobutyl group, dodecafluoropentyl group, perfluorooctyl group and the like.
Examples of the group containing two R ¹⁷ bonded to each other and containing a divalent fluorine atom having 2 to 10 carbon atoms include a tetrafluoroethylene group, a hexafluoropropylene group, an octafluorobutylene group, a decafluoropentylene group, An undecafluorohexylene group and the like can be mentioned.

Preferred anion sites of formula (7) include trifluoromethanesulfonate anion, perfluoro-n-butanesulfonate anion, perfluoro-n-octanesulfonate anion, 2-bicyclo [2.2.1] hept-2-yl- 1,1,2,2-tetrafluoroethanesulfonate anion, 2-bicyclo [2.2.1] hept-2-yl-1,1-difluoroethanesulfonate anion, 1-adamantylsulfonate anion and the following formula (9-1) ) To (9-7) and the like.

  The acid generator (B) is given by a combination of the cation and the anion exemplified above, but the combination is not particularly limited. In the present invention, the acid generator (B) may be used alone or in combination. Two or more types can be mixed and used.

Moreover, as a radiation sensitive acid generator (henceforth "other acid generator") other than the said acid generator (B) which can be used as a radiation sensitive acid generator in this invention, it is, for example. Onium salt compounds, halogen-containing compounds, diazoketone compounds, sulfone compounds, sulfonic acid compounds, and the like. Examples of these other acid generators include the following.
Onium salt compounds:
Examples of the onium salt compound include iodonium salts, sulfonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like.
Specific examples of the onium salt compound include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hepta-2. -Yl-1,1,2,2-tetrafluoroethanesulfonate, 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- Te La tetrafluoroethane sulfonate, cyclohexyl 2-oxo-cyclohexyl methyl trifluoromethanesulfonate, dicyclohexyl-2-oxo-cyclohexyl trifluoromethane sulfonate, and 2-oxo-cyclohexyl dimethyl sulfonium trifluoromethanesulfonate, and the like.

Halogen-containing compounds:
Examples of the halogen-containing compound include a haloalkyl group-containing hydrocarbon compound and a haloalkyl group-containing heterocyclic compound.
Specific examples of halogen-containing compounds include (trichloromethyl such as phenylbis (trichloromethyl) -s-triazine, 4-methoxyphenylbis (trichloromethyl) -s-triazine, 1-naphthylbis (trichloromethyl) -s-triazine. ) -S-triazine derivatives and 1,1-bis (4-chlorophenyl) -2,2,2-trichloroethane.
Diazo ketone compounds:
Examples of the diazo ketone compound include a 1,3-diketo-2-diazo compound, a diazobenzoquinone compound, a diazonaphthoquinone compound, and the like.
Specific examples of the diazo ketone include 1,2-naphthoquinonediazide-4-sulfonyl chloride, 1,2-naphthoquinonediazide-5-sulfonyl chloride, 1,2, naphthoquinonediazide of 2,3,4,4′-tetrahydroxybenzophenone. -4-sulfonic acid ester or 1,2-naphthoquinonediazide-5-sulfonic acid ester, 1,1,1-naphthoquinonediazide-4-sulfonic acid ester of 1,1,1-tris (4-hydroxyphenyl) ethane Examples include 2-naphthoquinonediazide-5-sulfonic acid ester.
Sulfone compounds:
Examples of the sulfone compound include β-ketosulfone, β-sulfonylsulfone, and α-diazo compounds of these compounds.
Specific examples of the sulfone compound include 4-trisphenacylsulfone, mesitylphenacylsulfone, bis (phenylsulfonyl) methane, and the like.
Sulfonic acid compounds:
Examples of the sulfonic acid compounds include alkyl sulfonic acid esters, alkyl sulfonic acid imides, haloalkyl sulfonic acid esters, aryl sulfonic acid esters, and imino sulfonates.
Specific examples of the sulfonic acid compound include benzoin tosylate, pyrogallol tris (trifluoromethanesulfonate), nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate, trifluoromethanesulfonylbicyclo [2.2.1] hept- 5-ene-2,3-dicarbodiimide, nonafluoro-n-butanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, perfluoro-n-octanesulfonylbicyclo [2.2 .1] Hept-5-ene-2,3-dicarbodiimide, 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonylbicyclo [2.2. 1] Hept-5-ene-2,3-dicarbodiimide, N- (trifluoromethanesulfonyl Xyl) 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, 1,8-naphthalenedicarboxylic imide trifluoromethanesulfonate, 1,8-naphthalenedicarboxylic imidononafluoro-n-butanesulfonate, 1,8-naphthalenedicarboxylic Examples include acid imido perfluoro-n-octane sulfonate.

  Among these other acid generators, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hepta- 2-yl-1,1,2,2-tetrafluoroethanesulfonate, 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 -Tetraph Oroethanesulfonate, cyclohexyl, 2-oxocyclohexyl, methylsulfonium trifluoromethanesulfonate, dicyclohexyl, 2-oxocyclohexylsulfonium trifluoromethanesulfonate, 2-oxocyclohexyldimethylsulfonium trifluoromethanesulfonate, trifluoromethanesulfonylbicyclo [2.2.1] hept -5-ene-2,3-dicarbodiimide, nonafluoro-n-butanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, perfluoro-n-octanesulfonylbicyclo [2. 2.1] Hept-5-ene-2,3-dicarbodiimide, 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyl Cyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, 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, 1,8-naphthalenedicarboxylic acid Imidotrifluoromethanesulfonate and the like are preferable. These other acid generators can be used alone or in admixture of two or more.

  In the present invention, the total amount of the acid generator (B) and the other acid generator used is usually 0.1 to 20 with respect to 100 parts by mass of the resin from the viewpoint of ensuring sensitivity and developability as a resist. Part by mass, preferably 0.5 to 10 parts by mass. In this case, if the total amount used is less than 0.1 parts by mass, the sensitivity and developability tend to decrease. On the other hand, if it exceeds 20 parts by mass, the transparency to radiation decreases and a rectangular resist pattern is obtained. There is a tendency to become difficult to get. Moreover, the usage-amount of another acid generator is 80 mass% or less normally with respect to the sum total of an acid generator (B) and another acid generator, Preferably it is 60 mass% or less.

It is preferable that the radiation sensitive resin composition of this invention contains a nitrogen-containing compound (C) with resin (A) and an acid generator (B). Other additives can be blended.
Nitrogen-containing compound (C)
The nitrogen-containing compound (C) used in the present invention acts as an acid diffusion control agent that controls the diffusion phenomenon in the resist film of the acid generated from the acid generator by exposure and suppresses undesired chemical reactions in non-exposed areas. To do. By blending such an acid diffusion controller, the storage stability of the resulting radiation-sensitive resin composition is improved, the resolution as a resist is further improved, and the process from exposure to heat treatment after exposure is improved. A change in the line width of the resist pattern due to fluctuations in the placement time (PED) can be suppressed, and a composition having extremely excellent process stability can be obtained.
Examples of the acid diffusion controller include “tertiary amine compound”, “amide group-containing compound”, “quaternary ammonium hydroxide compound”, “other nitrogen-containing heterocyclic compound” 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, cyclohexyldimethylamine, dicyclohexylmethylamine, tricyclohexylamine; aniline, N-methylaniline, N, N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4 -Aromatic amines such as methylaniline, 4-nitroaniline, 2,6-dimethylaniline, 2,6-diisopropylaniline; alkanolamines such as triethanolamine, N, N-di (hydroxyethyl) aniline; N , N, N ', N'-Tetramethylethylene Amine, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, 1,3-bis [1- (4-aminophenyl) -1-methylethyl] benzenetetramethylenediamine, bis (2- Examples thereof include dimethylaminoethyl) ether and bis (2-diethylaminoethyl) ether.

  Examples of the “amide group-containing compound” include Nt-butoxycarbonyldi-n-octylamine, Nt-butoxycarbonyldi-n-nonylamine, Nt-butoxycarbonyldi-n-decylamine, Nt- Butoxycarbonyldicyclohexylamine, Nt-butoxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-2-adamantylamine, Nt-butoxycarbonyl-N-methyl-1-adamantylamine, (S)-( -)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, (R)-(+)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, Nt-butoxycarbonyl-4-hydroxypiperidine Nt-butoxycarbonylpyrrolidine, Nt-butoxycarbonylpipe Gin, 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-butoxycarbonylhexamethylenediamine, N, N′-di-t-butoxycarbonyl-1 , 7-diaminoheptane, N, N′-di-t-butoxycarbonyl-1,8-diaminooctane, N, N′-di-t-butoxycarbonyl-1,9-diaminononane, N, N′-di- t-butoxycarbonyl-1,10-diaminodecane, N, N′-di-t-butoxycarbonyl-1,12-diaminododecane, N, N′-di-t-butoxy Nt- such as carbonyl-4,4′-diaminodiphenylmethane, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-methylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole, etc. Examples include a butoxycarbonyl group-containing amino compound.

Examples of the “quaternary ammonium hydroxide compound” include tetra-n-propylammonium hydroxide and tetra-n-butylammonium hydroxide.
Examples of the “nitrogen-containing heterocyclic compound” include: pyridine, 2-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 4-ethylpyridine, 2-phenylpyridine, 4-phenylpyridine, 2-methyl-4 -Pyridines such as phenylpyridine, nicotine, nicotinic acid, nicotinamide, quinoline, 4-hydroxyquinoline, 8-oxyquinoline, acridine; piperazines such as piperazine, 1- (2-hydroxyethyl) piperazine, and pyrazines , Pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, 3-piperidino-1,2-propanediol, morpholine, 4-methylmorpholine, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] Octane, imidazole, 4-methylimidazole 1-benzyl-2-methylimidazole, 4-methyl-2-phenylimidazole, benzimidazole, 2-phenylbenzimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-methylbenzimidazole, Examples thereof include Nt-butoxycarbonyl-2-phenylbenzimidazole.
The said nitrogen-containing compound (C) can be used individually or in mixture of 2 or more types.

  In the present invention, the total amount of the nitrogen-containing compound (C) used is usually less than 10 parts by mass, preferably less than 5 parts by mass with respect to 100 parts by mass of the resin, from the viewpoint of ensuring high sensitivity as a resist. . In this case, when the total usage exceeds 10 parts by mass, the sensitivity as a resist tends to be remarkably lowered. If the amount of nitrogen-containing compound used is less than 0.001 part by mass, the pattern shape and dimensional fidelity as a resist may be reduced depending on the process conditions.

Other additives The radiation-sensitive resin composition of the present invention may contain various additives such as an alicyclic additive having an acid-dissociable group, a surfactant, and a sensitizer as necessary. Can do.
The alicyclic additive having an acid-dissociable group is a component having an effect of further improving dry etching resistance, pattern shape, adhesion to a substrate, and the like.
Examples of such alicyclic additives include 1-adamantanecarboxylic acid, 2-adamantanone, 1-adamantanecarboxylic acid t-butyl, 1-adamantanecarboxylic acid t-butoxycarbonylmethyl, 1-adamantanecarboxylic acid α. -Butyrolactone ester, 1,3-adamantane dicarboxylic acid di-t-butyl, 1-adamantane acetate t-butyl, 1-adamantane acetate t-butoxycarbonylmethyl, 1,3-adamantane diacetate di-t-butyl, 2, Adamantane derivatives such as 5-dimethyl-2,5-di (adamantylcarbonyloxy) hexane; t-butyl deoxycholic acid, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid, 2-deoxycholic acid 2- Cyclohexyloxyethyl, deoxy Deoxycholic acid esters such as 3-oxocyclohexyl cholic acid, tetrahydropyranyl deoxycholic acid, mevalonolactone ester of deoxycholic acid; t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid, Lithocholic acid esters such as 2-cyclohexyloxyethyl lithocholic acid, 3-oxocyclohexyl lithocholic acid, tetrahydropyranyl lithocholic acid, mevalonolactone ester of lithocholic acid; dimethyl adipate, diethyl adipate, dipropyl adipate, din adipate -Alkyl carboxylic acid esters such as butyl and di-t-butyl adipate, and 3- [2-hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane and the like. These alicyclic additives can be used alone or in admixture of two or more.

A surfactant is a component that exhibits an effect of improving coating properties, 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.), F-top EF301, EF303, EF352 (manufactured by Tochem Products Co., Ltd.), Megafax F171, F173 (manufactured by Dainippon Ink & Chemicals, Inc.), Florard FC430, FC431 ( Sumitomo 3M Limited), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-105, SC-106 (Asahi Glass Co., Ltd.) And the like. These surfactants can be used alone or in admixture of two or more.
The sensitizer absorbs radiation energy and transmits the energy to the acid generator (B), thereby increasing the amount of acid produced. It has the effect of improving the apparent sensitivity.
Examples of such sensitizers include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines, and the like. These sensitizers can be used alone or in admixture of two or more.
In addition, by blending a dye or pigment, the latent image of the exposed area can be visualized, and the influence of halation during exposure can be alleviated, and by blending an adhesion aid, adhesion to the substrate can be improved. it can. Furthermore, examples of additives other than the above include alkali-soluble resins, low-molecular alkali solubility control agents having an acid-dissociable protecting group, antihalation agents, storage stabilizers, antifoaming agents, and the like.

Preparation of Composition Solution The radiation-sensitive resin composition of the present invention is usually used in a solvent so that the total solid content is usually 1 to 50% by mass, preferably 1 to 25% by mass, when used. After dissolution, the composition solution is prepared by, for example, filtering with a filter having a pore size of about 200 nm.
Examples of the solvent used for the preparation of the composition solution include 2-butanone, 2-pentanone, 3-methyl-2-butanone, 2-hexanone, 4-methyl-2-pentanone, and 3-methyl-2- Linear or branched ketones such as pentanone, 3,3-dimethyl-2-butanone, 2-heptanone, 2-octanone; cyclopentanone, 3-methylcyclopentanone, cyclohexanone, 2-methylcyclohexanone, 2 Cyclic ketones such as 1,6-dimethylcyclohexanone and isophorone; propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate, propylene glycol mono-i-propyl ether acetate, propylene glycol Propylene glycol monoalkyl ether acetates such as propylene glycol mono-i-butyl ether acetate, propylene glycol mono-sec-butyl ether acetate, propylene glycol mono-t-butyl ether acetate; methyl 2-hydroxypropionate; 2-hydroxypropionic acid ethyl, 2-hydroxypropionic acid n-propyl, 2-hydroxypropionic acid i-propyl, 2-hydroxypropionic acid n-butyl, 2-hydroxypropionic acid i-butyl, 2-hydroxypropionic acid sec- Alkyl 2-hydroxypropionates such as butyl and t-butyl 2-hydroxypropionate; methyl 3-methoxypropionate, 3-methoxypropioate In addition to alkyl 3-alkoxypropionates such as ethyl acetate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, t-butyl alcohol, cyclohexanol , Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di-n-butyl ether , Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethyl Glycol mono-n-propyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, toluene, xylene, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxy acetate, hydroxy Ethyl acetate, methyl 2-hydroxy-3-methylbutyrate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutylpropionate, 3-methyl-3-methoxybutylbutyrate Rate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl acetoacetate, ethyl acetoacetate, methyl pyruvate, ethyl pyruvate, N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethyl Ruacetamide, benzyl ethyl ether, di-n-hexyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, caproic acid, caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyl oxalate , Diethyl maleate, γ-butyrolactone, ethylene carbonate, propylene carbonate and the like.

Among these, linear or branched ketones, cyclic ketones, propylene glycol monoalkyl ether acetates, alkyl 2-hydroxypropionate, alkyl 3-alkoxypropionate, γ-butyrolactone and the like are preferable. .
These solvents can be used alone or in admixture of two or more.

Method for Forming Resist Pattern The radiation-sensitive resin composition of the present invention is particularly useful as a chemically amplified resist. In the above chemically amplified resist, the acid-dissociable group in the resin (A) is dissociated by the action of the acid generated from the acid generator by exposure to generate a carboxyl group. The solubility in the developer is increased, and the exposed portion is dissolved and removed by the 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 a heat treatment (hereinafter referred to as “PB”) is performed in advance in some cases.

In the case of immersion exposure, an upper layer film can be formed on the photoresist film using the upper layer film forming composition. By forming the upper layer film, it is possible to protect the photoresist film and to prevent contamination of the lens of the projection exposure apparatus caused by elution of components contained in the resist from the photoresist film to the liquid.
The photoresist film and the upper layer film are irradiated with radiation through a mask having a predetermined pattern through an immersion medium such as water, and then developed to form a resist pattern. The pH of water filled between the photoresist film and the upper film can be adjusted. In particular, pure water is preferred. In addition to pure water, it is preferable that the liquid has a refractive index at 193 nm that is greater than or equal to the refractive index of water at 193 nm.
Moreover, it is preferable that the refractive index in wavelength 193nm of the resist film formed with the radiation sensitive resin composition of this invention is 1.72 or more. By using a resin containing a repeating unit represented by the formula (1), the refractive index at a wavelength of 193 nm can be 1.72 or more because a specific skeleton promotes a red shift of the UV spectrum.

  The radiation used when exposing the photoresist film is appropriately selected from visible rays, ultraviolet rays, far ultraviolet rays, X-rays, charged particle beams, etc., depending on the type of acid generator used. However, a deep ultraviolet ray represented by an ArF excimer laser (wavelength 193 nm) or a KrF excimer laser (wavelength 248 nm) is preferable, and an ArF excimer laser (wavelength 193 nm) is particularly preferable. Moreover, exposure conditions, such as exposure amount, are suitably selected according to the compounding composition of a radiation sensitive resin composition, the kind of additive, etc., and immersion exposure may be sufficient as it. In the present invention, it is preferable to perform heat treatment (PEB) after exposure. By this PEB, the dissociation reaction of the acid dissociable group in the resin (A) 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 be formed, and in order to prevent the influence of basic impurities and the like 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 exposed resist film is developed to form a predetermined resist pattern. Examples of the developer used for development include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, and di-n-propylamine. , Triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4.3.0] An alkaline aqueous solution in which at least one of alkaline compounds such as 5-nonene is dissolved is preferable. The concentration of the alkaline aqueous solution is usually 10% by mass or less. In this case, if the concentration of the alkaline aqueous solution exceeds 10% by mass, the unexposed area may be dissolved in the developer, which is not preferable.

  Further, for example, an organic solvent can be added to the developer composed of the alkaline aqueous solution. Examples of organic solvents include ketones such as acetone, methyl ethyl ketone, methyl i-butyl ketone, cyclopentanone, cyclohexanone, 3-methylcyclopentanone, and 2,6-dimethylcyclohexanone; methyl alcohol, ethyl alcohol, n-propyl alcohol Alcohols such as i-propyl alcohol, n-butyl alcohol, t-butyl alcohol, cyclopentanol, cyclohexanol, 1,4-hexanediol and 1,4-hexanedimethylol; ethers such as tetrahydrofuran and dioxane; Examples thereof include esters such as ethyl acetate, n-butyl acetate and i-amyl acetate; aromatic hydrocarbons such as toluene and xylene; phenol, acetonylacetone and dimethylformamide. These organic solvents can be used alone or in admixture of two or more. The amount of the organic solvent used is preferably 100% by volume or less with respect to the alkaline aqueous solution. In this case, if the amount of the organic solvent used exceeds 100% by volume, the developability is lowered, and there is a possibility that the remaining development in the exposed area increases. In addition, an appropriate amount of a surfactant or the like can be added to the developer composed of an alkaline aqueous solution. In addition, after developing with the developing solution which consists of alkaline aqueous solution, generally it wash | cleans with water and dries.

上記化合物（Ｍ−１）１３．６２ｇ（５０モル％）、化合物（Ｍ−２）１１．３８ｇ（５０モル％）を２−ブタノン５０ｇ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）２．０６ｇを投入した単量体溶液を準備し、２５ｇの２−ブタノンを投入した５００ｍｌの三口フラスコを３０分窒素パージした。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、５００ｇのメタノールへ投入し、析出した白色粉末をろ別した。ろ別された白色粉末を２度１００ｇ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、白色粉末の重合体を得た（１４ｇ、収率５６％）。この重合体はＭｗが８，２００、Ｍｗ／Ｍｎが２．１５、¹³Ｃ-ＮＭＲ分析の結果、化合物（Ｍ−１）、化合物（Ｍ−２）に由来する各繰り返し単位の含有率が５０．７：４９．３（モル％）の共重合体であった。この重合体を樹脂（Ａ−１）とする。 Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Here, the part is based on mass unless otherwise specified.
Example 1
[Synthesis of polymer]

13.62 g (50 mol%) of the compound (M-1) and 11.38 g (50 mol%) of the compound (M-2) were dissolved in 50 g of 2-butanone, and further dimethyl 2,2′-azobis (2- A monomer solution charged with 2.06 g of methyl propionate) was prepared, and a 500 ml three-necked flask charged with 25 g of 2-butanone was 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 was cooled with water to 30 ° C. or less, poured into 500 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 100 g of methanol on the slurry, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder polymer (14 g, yield 56%). . This polymer has an Mw of 8,200, an Mw / Mn of 2.15, and as a result of ¹³ C-NMR analysis, the content of each repeating unit derived from the compound (M-1) and the compound (M-2) is 50. 7: 49.3 (mol%) copolymer. This polymer is referred to as “resin (A-1)”.

Each measurement / evaluation of the obtained polymer was performed in the following manner.
(1) Mw and Mn
Gel permeation based on monodisperse polystyrene using GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL) manufactured by Tosoh Corporation under the analysis conditions of a flow rate of 1.0 ml / min, elution solvent tetrahydrofuran, and column temperature of 40 ° C. It was measured by an association chromatography (GPC). Further, the degree of dispersion Mw / Mn was calculated from the measurement results.
(2) ¹³ C-NMR analysis of ¹³ C-NMR analysis the polymer, using a Nippon Denshi Co. "JNM-EX270", was performed using CDCL ₃ as measurement solvent. The NMR chart is shown in FIG.

Example 2
[Preparation of radiation-sensitive resin composition]
With respect to 100 parts by mass of the resin (A-1), 3.0 parts by mass of triphenylsulfonium nonafluoro-n-butanesulfonate as the radiation-sensitive acid generator (B) and Nt-butoxy as the acid diffusion inhibitor 0.27 parts by mass of carbonylpyrrolidine, 960 parts by mass of cyclohexanone as a main solvent, and 410 parts by mass of propylene glycol monomethyl ether acetate as an auxiliary solvent were added, and the respective components were mixed to obtain a homogeneous solution. Then, the coating liquid which consists of a radiation sensitive resin composition was prepared by filtering using a membrane filter with the hole diameter of 200 nm (total solid content concentration of about 7 mass%).

Each measurement / evaluation of the obtained radiation sensitive resin composition was performed in the following manner.
(1) Refractive Index Measurement A radiation sensitive resin composition is spin-coated on a silicon substrate with CLEAN TRACK ACT8 “manufactured by Tokyo Electron”, and subjected to PB at 80 ° C. for 60 seconds, whereby a resist film having a film thickness of 150 nm Formed. The refractive index of the resist film was measured using a spectroscopic ellipsometer (“VUV-VASE”, manufactured by JA Woollam). As a result of the measurement, the refractive index at 193 nm of the resist film was 1.75.
(2) Characteristic curve measurement:
A radiation sensitive resin composition was spin-coated on a silicon substrate by CLEAN TRACK ACT8 “manufactured by Tokyo Electron” and PB was performed at 80 ° C. for 60 seconds to form a resist film having a thickness of 150 nm. This resist film was exposed through quartz having no pattern by an ArF excimer laser exposure apparatus (“NSR S306C”, manufactured by Nikon, illumination condition: NA 0.75 sigma 0.85). Thereafter, PEB was performed at 130 ° C. for 60 seconds, and then developed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 30 seconds, washed with water, and dried to prepare a wafer for measuring characteristic curves. . Next, the film thickness at each exposure amount was measured with an automatic film thickness measurement device (“VM-2010”, manufactured by Dainippon Screen) to confirm the correlation between the exposure amount and the film thickness. The result is shown in FIG.

  As is apparent from the measurement of the characteristic curve in FIG. 2, the radiation-sensitive resin composition for immersion exposure according to the present invention has a refractive index of 193 nm, which is higher than usual, of 1.75, and depending on the exposure amount. Since the amount of the remaining film changes and finally all the films are dissolved in the developer and sufficient contrast is obtained, it is expected to function as a resist material. As a next generation of immersion exposure with water (refractive index at 193 nm is 1.44) which is currently mass-produced in the future, this radiation sensitive resin composition is 1 even when an immersion liquid of 1.71 or more is used. Since it has a refractive index of .72 or more, exposure light can sufficiently enter the resist film, and high sensitivity can be maintained.

  Since the radiation sensitive resin composition for immersion exposure using the novel polymer of the present invention has a refractive index of 193 nm of 1.72 or more, a high refractive index immersion liquid, which is a next generation immersion technique, was used. It can be applied in some cases.

2 is an NMR chart of Example 1. 6 is a correlation diagram between an exposure amount and a film thickness in Example 2. FIG.

Claims (6)

It contains a repeating unit represented by the following formula (1) and a repeating unit obtained from a monomer having a side chain represented by the following formula (2), and has a polystyrene-reduced mass average molecular weight of 1 by gel permeation chromatography. , 000～100,000 der is, based on all repeating units, the content of the repeating unit is 10 to 90 mol% of the following formula (1), a side chain represented by the following formula (2) polymer content of recurring units derived from monomers and wherein 10 to 90 mol% der Rukoto with.

(In Formula (1), R ¹ represents a hydrogen atom, a methyl group, or a trifluoromethyl group, A represents a single bond or a divalent linking group, and three X's independently represent an oxygen atom or a sulfur atom. And at least one X represents a sulfur atom, and R ² represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alicyclic hydrocarbon group having 4 to 20 carbon atoms. )

(In Formula (2), R ³ independently represents a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or a linear or branched alkyl group having 1 to 4 carbon atoms. And at least one of R ³ is the alicyclic hydrocarbon group or a derivative thereof, or any two R ³ are bonded to each other, and together with the carbon atom to which each is bonded, 20 divalent alicyclic hydrocarbon groups or derivatives thereof, and the remaining R ³ is a linear or branched alkyl group having 1 to 4 carbon atoms, or a monovalent fat having 4 to 20 carbon atoms Represents a cyclic hydrocarbon group or a derivative thereof.) The formula (1) is a repeating unit derived from at least one monomer selected from the following formula (1-2), formula (1-3), formula (1-6), and formula (1-7). The polymer according to claim 1, wherein the polymer is present.

(In Formula (1-2), Formula (1-3), Formula (1-6), and Formula (1-7), R ¹ represents a hydrogen atom, a methyl group, or a trifluoromethyl group.)   The monomer having a side chain represented by the formula (2) is (meth) acrylic acid 2-methyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyladamantyl-2-yl ester, (meth) Acrylic acid-2-methylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-2-ethylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid 1- (bicyclo [2.2.1] hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) acrylic acid 1-methyl-1-cyclopentyl ester, (meth) acrylic acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, or (Meth) polymer of claim 1 or claim 2, wherein the acrylic acid 1-ethyl-1-cyclohexyl ester. A radiation-sensitive resin composition comprising a resin (A) that becomes alkali-soluble by the action of an acid and a radiation-sensitive acid generator (B),
The radiation sensitive resin composition, wherein the resin (A) is the polymer according to claim 1 , claim 2 or claim 3 . The radiation-sensitive resin composition according to claim 4, wherein the resist film formed of the radiation-sensitive resin composition has a refractive index of 1.72 or more at a wavelength of 193 nm. A resist pattern forming method including immersion exposure in which radiation is irradiated between a lens and a photoresist film through an immersion exposure liquid having a refractive index at a wavelength of 193 nm larger than that of air,
The photoresist film is formed using the radiation-sensitive resin composition according to claim 4 or claim 5 ,
The method for forming a resist pattern, wherein the immersion exposure liquid is a liquid having a refractive index at 193 nm equal to or higher than that of water at 193 nm.

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