JP2008050476A - Block copolymer and radiation-sensitive resin composition - Google Patents

Abstract

The present invention can be used for a chemically amplified resist having excellent sensitivity, resolution, and density dependency.
A partial component (A1) having a plurality of different partial components, wherein the plurality of different partial components include a repeating unit having a lactone skeleton in the side chain and a repeating unit having an acid dissociable group. And a partial structural component (A2) containing a repeating unit having a cyano group in the side chain, and a mass average molecular weight in terms of standard polystyrene measured by gel permeation chromatography is 1,000 or more and 200,000 or less.
[Selection figure] None

Description

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

In the field of microfabrication represented by the manufacture of integrated circuit elements, in order to obtain a higher degree of integration, recently, an ArF excimer laser (wavelength 193 nm), an F ₂ excimer laser (wavelength 157 nm) or the like has been used. Therefore, there is a need for a lithography technique that enables fine processing at the same level. As a radiation-sensitive resin composition suitable for irradiation with such an excimer laser, a chemical utilizing the chemical amplification effect by the component having an acid-dissociable functional group and the acid generator which is a component generating an acid by irradiation with radiation. Many amplified radiation-sensitive compositions have been proposed. For example, as a resin component, a polymer compound for a photoresist having a specific structure including a monomer unit having a norbornane ring derivative as a resin component is known (Patent Documents 1 and 2).
JP 2002-201232 A JP 2002-145955 A

On the other hand, living radical polymerization in which radical polymerization is controlled using a special chain transfer agent is known, and the chain transfer agent has also been proposed (Patent Documents 3 to 6, Non-Patent Document 1).
An acid-dissociable group-containing polymer using living radical polymerization is also known (Patent Document 7).
International Publication WO98 / 01478 International Publication No. WO99 / 05099 US Pat. No. 6,395,850 US Patent Publication No. 6,380,335 JP 2005-156725 A Macromolecules 1999, 32, 6977-6980

However, when a higher degree of integration is required in the semiconductor field, a radiation-sensitive resin composition that is a resist is required to have better resolution. One of the reasons why the resolution cannot be obtained is a pattern profile defect in which the resist pattern after development becomes thinner in the upper part and becomes thicker in the lower part.
At the same time, the demand for reducing the line edge roughness (hereinafter referred to as LER) of the pattern has become stronger as the miniaturization progresses. As the semiconductor industry advances in miniaturization, there is an urgent need to develop a radiation-sensitive resin composition that excels in resolution and pattern profile and satisfies the requirements for low LER.
Conventionally, resins used for radiation-sensitive resin compositions tend to have lower LER characteristics as the molecular weight increases, and heat resistance decreases and etching resistance tends to deteriorate as the molecular weight decreases. For this reason, in normal radical polymerization in which the width of the molecular weight distribution is large, there is a tendency to reduce the average molecular weight in order to improve the LER characteristics even at the sacrifice of etching resistance. Development of a resin that can reduce the width of the molecular weight distribution and optimize the average molecular weight is desired. On the other hand, an acid-dissociable group-containing polymer using living radical polymerization is also known, but sufficient LER characteristics to cope with a higher degree of integration have not been obtained.
In addition, as the resist pattern becomes more complicated, it is necessary to reduce the dependency on the density that the line width changes depending on the degree of integration of the resist pattern.

  The problem to be solved is applicable to chemically amplified resists that can be applied to short-wavelength radiation typified by far-ultraviolet rays that can cope with the progress of miniaturization in integrated circuit elements, and that are excellent in sensitivity, resolution, and density dependence. The radiation-sensitive resin composition that can be obtained is not obtained.

式（Ｘ−１）において、Ｒ^aは、置換または非置換の炭素数１〜２０の炭化水素基を表し、Ｚは置換基およびヘテロ原子を含んでいてもよい炭素数２〜１５の１価の有機基を表す。
また、上記Ｚは下記式（Ｘ−２)で表される置換基であることを特徴とする。

式（Ｘ−２)において、Ｒ^b、Ｒ^cおよびＲ^dは、相互に独立に水素原子、置換または非置換の炭素数１〜８の炭化水素基、置換または非置換のヘテロ原子を含む炭素数１〜８の炭化水素基、または、Ｒ^b、Ｒ^cおよびＲ^dのいずれか２つが相互に結合して形成される構成原子数が３〜２０の非水素原子を含む環を表す。
本発明の感放射線性樹脂組成物は、上記ブロック共重合体を樹脂成分とする酸解離性基含有重合体と、感放射線性酸発生剤とを含有することを特徴とする。 The block copolymer of the present invention has a plurality of different partial constituents, and the plurality of different partial constituents contain a repeating unit having a lactone skeleton in the side chain and a repeating unit having an acid-dissociable group. A component (A1) and a partial component (A2) containing a repeating unit having a cyano group in the side chain, and a mass average molecular weight (hereinafter abbreviated as Mw) in terms of standard polystyrene measured using gel permeation chromatography Is from 1,000 to 200,000.
In addition, the partial constituent component (A2) is at the block terminal of the block copolymer.
Further, the copolymerization of the partial constituent component (A1) and the partial constituent component (A2) is at least copolymerized by living radical polymerization using a chain transfer agent represented by the following formula (X-1). Features.

In Formula (X-1), R ^a represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, and Z represents a monovalent group having 2 to 15 carbon atoms that may contain a substituent and a hetero atom. Represents an organic group.
The above Z is a substituent represented by the following formula (X-2).

In the formula (X-2), R ^b , R ^c and R ^d are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group having 1 to 8 carbon atoms, a carbon containing a substituted or unsubstituted heteroatom. This represents a hydrocarbon group having 1 to 8 or a ring containing a non-hydrogen atom having 3 to 20 constituent atoms formed by bonding any two of R ^b , R ^c and R ^d to each other.
The radiation sensitive resin composition of the present invention comprises an acid dissociable group-containing polymer containing the block copolymer as a resin component and a radiation sensitive acid generator.

  The block copolymer of the present invention contains a partial component (A2) containing a repeating unit having an average molecular weight controlled by living radical polymerization and having a cyano group in the side chain. Therefore, the radiation-sensitive resin composition comprising the block copolymer as a resin component is transparent to radiation as a chemically amplified resist sensitive to actinic radiation, particularly far ultraviolet rays represented by ArF excimer laser (wavelength 193 nm). High resolution, high resolution and excellent density dependency.

In the present invention, a block containing a repeating unit having a cyano group in the side chain is polymerized using a specific chain transfer agent as a partial component of the block copolymer. This is based on the knowledge that by using the obtained block copolymer, a radiation-sensitive resin composition having excellent basic physical properties as a resist, high resolution performance, and excellent density dependency can be obtained.
The chain transfer agent of the present invention may be a reversible addition-cleavage chain transfer agent. The reversible addition chain transfer agent here refers to what is generally called RAFT (Reversible Addition-Fragmentation Chain Transfer) Agent in the literature (see Non-Patent Document 1). Z in the reversible addition-cleavage chain transfer agent is preferably bonded to the> C═S group in the molecule represented by the formula (X-1) via a nitrogen atom, a sulfur atom, or an oxygen atom. In the case of a nitrogen atom, dithiocarbamate is formed, and in the case of a sulfur atom, dithiocarbonate is formed.
R ^a is preferably an organic group that can be cleaved as an R ^a radical in the chain transfer agent represented by the formula (X-1). As R ^a , specifically, —CH ₂ Ph, —CH (CH ₃ ) CO ₂ CH ₂ CH ₃ , —CH (CO ₂ CH ₂ CH ₃ ) ₂ , —C (CH ₃ ) ₂ CN, —CH (Ph) CN, —C (CH ₃ ) ₂ CO ₂ R ′ (R ′ represents an alkyl, aryl group, etc.), —C (CH ₃ ) ₂ Ph. Ph represents a phenyl group.

式（Ｘ−３）において、Ｒ^ｅ、Ｒ^ｆとＲ^ｇはそれぞれ独立で水素原子、置換または非置換の炭化水素基、置換または非置換の炭化水素基から選ばれる基である。 In the formula (X-2), the substituted or unsubstituted hydrocarbon group represented by R ^b , R ^c and R ^d is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or non-substituted group. Examples of the hydrocarbon group containing a substituted or unsubstituted hetero atom as the substituted alkenyl group include a substituted or unsubstituted acyl group, a substituted or unsubstituted aroyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted group And monovalent organic groups such as a heteroaryl group, a substituted or unsubstituted heterocyclo group, a substituted or unsubstituted alkylsulfonyl group, a substituted or unsubstituted alkylsulfinyl group, and a substituted or unsubstituted arylsulfinyl group.
In the formula (X-2), examples of the group in which any two of R ^b , R ^c and R ^d are bonded to each other and the ring has 3 to 50 atoms are substituted or unsubstituted Of the pyrazole ring structure. As an example, an example of a pyrazole ring represented by the formula (X-3) is shown.

In Formula (X-3), R ^e , R ^f and R ^g are each independently a group selected from a hydrogen atom, a substituted or unsubstituted hydrocarbon group, and a substituted or unsubstituted hydrocarbon group.

Specific examples of the chain transfer agent that can be used in the present invention are represented by the following formulas (CTA-1) to (CTA-4).

The chain transfer agent used in the present invention can be used in combination with a radical polymerization initiator.
Examples of the radical polymerization initiator that can be used in the present invention include a thermal polymerization initiator, a redox polymerization initiator, and a photopolymerization initiator. Examples thereof include polymerization initiators such as peroxides and azo compounds. Although not particularly limited, specific radical polymerization initiators include t-butyl hydroperoxide, t-butyl perbenzoate, benzoyl peroxide, 2,2′-azobis (2,4-dimethylvaleronitrile), 2, Examples include 2′-azobisisobutyronitrile (AIBN), 1,1′-azobis (cyclohexanecarbonitrile), dimethyl-2,2′-azobisisobutyrate (MAIB), and the like.

The block copolymer of the present invention contains a partial structural component (A1) containing a repeating unit having a lactone skeleton in the side chain and a repeating unit having an acid dissociable group, and a repeating unit having a cyano group in the side chain. A partial component (A2) is contained as a block. By containing the partial constituent component (A1), an alkali-insoluble or alkali-insoluble block copolymer that becomes readily alkali-soluble by the action of an acid is obtained.
The term “alkali-insoluble or alkali-insoluble” as used herein refers to alkali development conditions (preferably used when forming a resist pattern from a resist film formed from a radiation-sensitive resin composition containing a block copolymer). when developing a film using only a block copolymer in place of the resist film under an alkaline aqueous solution having a pH of 8 to 14, more preferably an alkaline aqueous solution having a pH of 9 to 14). It means that 50% or more of the initial film thickness of the film remains after development. “Alkali readily soluble” means the property that less than 50% of the initial film thickness is lost by dissolving the coating by the same treatment.

The block copolymer has a polystyrene-equivalent Mw by gel permeation chromatography (GPC) of 1,000 to 200,000, preferably Mw of 2,000 to 4,000. The polydispersity (Mw / Mn) is 1.3 or less, preferably the polydispersity (Mw / Mn) is 1.2 or less. The lower limit value of the polydispersity is theoretically 1.0, but the closer to this, the better. Here, Mn represents a number average molecular weight.
When the Mw is less than 1000, the heat resistance when used as a resist is lowered and the etching resistance is deteriorated. On the other hand, when Mw exceeds 200000, LER decreases.
Mw and Mn can be measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard. Moreover, Mw can be controlled by increasing or decreasing the amount of the chain transfer agent in the polymerization reaction.

上式において、Ｒは水素原子またはメチル基を、Ｒ¹は、相互に独立に炭素数１〜４の直鎖状または分岐状のアルキル基をそれぞれ表す。
また、上式において、シクロアルカン由来の脂環族環は、置換基を有していてもよく、例えば、メチル基、エチル基、ｎ−プロピル基、ｉ−プロピル基、ｎ−ブチル基、２−メチルプロピル基、１−メチルプロピル基、ｔ−ブチル基等の炭素数１〜４の直鎖状、分岐状または環状のアルキル基の１種以上あるいは１個以上で置換した骨格等が挙げられる。 好ましい酸解離性基を含有する単量体としては、解像度を上げることができる式（ｍ−１）、式（ｍ−２）、または式（ｍ−３）であり、好ましいＲはメチル基、同Ｒ¹はメチル基またはエチル基である。 In the partial constituent component (A1) of the block copolymer, the repeating unit having an acid dissociable group is obtained by copolymerizing a monomer containing an acid dissociable group.
Examples of the monomer containing an acid dissociable group include monomers represented by the following formulas (m-1) to (m-7).

In the above formula, R represents a hydrogen atom or a methyl group, and R ¹ independently represents a linear or branched alkyl group having 1 to 4 carbon atoms.
In the above formula, the cycloalkane-derived alicyclic ring may have a substituent, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2 And a skeleton substituted with one or more of linear, branched or cyclic alkyl groups having 1 to 4 carbon atoms such as -methylpropyl group, 1-methylpropyl group and t-butyl group. . The monomer containing a preferred acid-dissociable group is the formula (m-1), the formula (m-2), or the formula (m-3) that can increase the resolution, and preferred R is a methyl group, R ¹ is a methyl group or an ethyl group.

上式において、Ｒは水素原子またはメチル基を表す。また、シクロアルカン由来の脂環族環は、置換基を有していてもよく、例えば、メチル基、エチル基、ｎ−プロピル基、ｉ−プロピル基、ｎ−ブチル基、２−メチルプロピル基、１−メチルプロピル基、ｔ−ブチル基等の炭素数１〜４の直鎖状、分岐状または環状のアルキル基の１種以上あるいは１個以上で置換した骨格等が挙げられる。 In the partial constituent component (A1) of the block copolymer, the repeating unit having a lactone skeleton in the side chain is preferably copolymerized with a monomer represented by the following formula (m-8). Moreover, the monomer represented by a following formula (m-9) is mentioned as a monomer which produces | generates another preferable repeating unit.

In the above formula, R represents a hydrogen atom or a methyl group. The cycloalkane-derived alicyclic ring may have a substituent, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group. , A skeleton substituted with one or more linear, branched or cyclic alkyl groups having 1 to 4 carbon atoms such as 1-methylpropyl group and t-butyl group.

  Examples of other monomers constituting the partial component (A1) include, for example, norbornyl (meth) acrylate, isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, and (meth) acrylic. Acid tetracyclodecanyl, (meth) acrylic acid adamantyl, (meth) acrylic acid-3-hydroxy-1-adamantyl, (meth) acrylic acid-3,5-dihydroxy-1-adamantyl, (meth) acrylic acid-3 (Meth) acrylic acid esters having a bridged hydrocarbon skeleton such as -oxo-1-adamantyl, adamantyl methyl (meth) acrylate;

Carboxyl-containing esters having a bridged hydrocarbon skeleton of unsaturated carboxylic acid such as carboxynorbornyl (meth) acrylate, carboxytricyclodecanyl (meth) acrylate, and carboxytetracyclodecanyl (meth) acrylate , (Meth) acrylic acid esters having no bridged hydrocarbon skeleton, α-hydroxymethylacrylic acid esters, unsaturated amide compounds, nitrogen-containing vinyl compounds, unsaturated carboxylic acid (anhydrides), unsaturated Carboxylic acid-containing esters having no bridged hydrocarbon skeleton, carboxylic acid-containing (meth) acryloyloxylactone compounds, α- (meth) acryloyloxy-γ-butyrolactone, β- (meth) Acryloyloxy-γ-butyrolactone, α- (meth) acryloyloxy-δ-valerolac , Monofunctional monomers such as (meth) acryloyloxylactone compounds having no acid dissociable groups such as β- (meth) acryloyloxy-δ-valerolactone, 1,2-adamantanediol di (meth) Multifunctional having bridged hydrocarbon skeleton such as acrylate, 1,3-adamantanediol di (meth) acrylate, 1,4-adamantanediol di (meth) acrylate, tricyclodecanyl dimethylol di (meth) acrylate Examples thereof include a polyfunctional monomer such as a monomer and a polyfunctional monomer having no bridged hydrocarbon skeleton.
In the block copolymer, other repeating units may be present alone or in combination of two or more.

上式において、Ｒは水素原子またはメチル基を表す。また、Ｘは、単結合または２価の連結基を表す。２価の連結基としては、置換または非置換の直鎖状、分岐状もしくは環式アルキレン基、置換または非置換のアリーレン基、置換または非置換の直鎖状、分岐状もしくは環式アルキレンカルボニル基、置換または非置換のアリーレンカルボニル基が挙げられる。
好ましいＸは連結基のない単結合であり、好ましい具体例としては、アクリロニトリル、メタクリロニトリルが挙げられる。
また、部分構成成分（Ａ２）には、他の繰り返し単位を含むことができる。他の繰り返し単位としては、ラクトン構造をもつ（メタ）アクリレートおよび酸解離性保護基をもつ（メタ）アクリレート等が挙げられる。 The partial component (A2) constituting the block copolymer is obtained by copolymerizing a monomer represented by the following formula (m-10).

In the above formula, R represents a hydrogen atom or a methyl group. X represents a single bond or a divalent linking group. The divalent linking group includes a substituted or unsubstituted linear, branched or cyclic alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted linear, branched or cyclic alkylenecarbonyl group. A substituted or unsubstituted arylenecarbonyl group.
Preferred X is a single bond having no linking group, and preferred specific examples include acrylonitrile and methacrylonitrile.
Further, the partial component (A2) can contain other repeating units. Examples of other repeating units include (meth) acrylate having a lactone structure and (meth) acrylate having an acid dissociable protecting group.

  In the block copolymer, the proportion of the partial constituent component (A1) is 60 to 99.5 mol%, preferably 70 to 95 mol%, based on all repeating units in the polymer constituting the copolymer. . Moreover, the ratio of a partial structural component (A2) is 0.5-10 mol% with respect to all the repeating units in the polymer which comprises a copolymer, Preferably it is 1-5 mol%. If the proportion of the partial constituent component (A2) is less than 0.5 mol%, the effect of the present invention tends not to be obtained, and if it exceeds 10 mol%, the sensitivity of the resist decreases.

In the partial component (A1), the proportion of the repeating unit having an acid dissociable group in the side chain is 20 to 80 mol%, preferably with respect to all repeating units in the polymer constituting the partial component (A1). Is 30-70 mol%. Moreover, the repeating unit which has a lactone skeleton in a side chain is 20-80 mol% with respect to all the repeating units in the polymer which comprises a partial structural component (A1), Preferably it is 30-70 mol%.
If the ratio of the repeating unit having an acid dissociable group in the side chain is less than 20 mol%, contrast during development of the resist cannot be obtained, resolution tends to deteriorate, and development defects tend to be caused. Above the mol%, the contrast to the developer is improved, but the decrease in developability tends to deteriorate significantly. Further, if the ratio of the repeating unit having a lactone skeleton in the side chain is less than 20 mol%, the adhesion to the substrate tends to be insufficient, while if it exceeds 80 mol%, the resolution tends to deteriorate.
In addition, the ratio of another repeating unit is 30 mol% or less with respect to all the repeating units in the polymer which comprises a partial structural component (A1), Preferably it is 20 mol% or less.

  In the partial component (A2), the proportion of the repeating unit having a cyano group in the side chain is 30 mol% or more, preferably 50 mol, based on all repeating units in the polymer constituting the partial component (A2). % Or more. If it is less than 30 mol%, the density dependency of the resist pattern tends to deteriorate.

In the block copolymer of the present invention, the partial constituent component (A1) and the partial constituent component (A2) were each polymerized by living polymerization in order, and the active constituent was left at the terminal of the partial constituent component (A1). A method of polymerizing the monomer constituting the partial constituent component (A2) later, a method in which the partial constituent component (A1) and the partial constituent component (A2) are each made into a polymer and then bonded to each other. Can do.
In the block copolymer of the present invention, it is preferable that the partial constituent component (A2) is at the end of the block copolymer because the effect of reducing the dependence on density is high.

As a manufacturing method of the block copolymer of this invention, it is preferable to make it copolymer by living radical polymerization using the chain transfer agent represented by Formula (X-1) in addition to a radical polymerization initiator.
In order to achieve a sufficient polymerization rate, it is necessary to add a sufficiently high concentration of radical polymerization initiator. However, if the ratio between the radical polymerization initiator amount and the chain transfer agent amount is too high, a radical-radical coupling reaction occurs and an undesirable non-living radical polymer is formed, so that the obtained polymer has a molecular weight and molecular weight distribution. The part which has the characteristic which is not controlled in polymer characteristics, such as is included. The molar ratio between the radical polymerization initiator amount and the chain transfer agent amount is (1: 1) to (0.005: 1), preferably (1: 1) to (1:10).
Moreover, in order to make Mw 1000 or more and 200000 or less and polydispersity 1.3 or less, radical polymerization initiator amount is 1-15 mass% with respect to monomer whole quantity, Preferably 2-10 mass%, The amount of chain transfer agent is 2 to 20% by mass, preferably 3 to 10% by mass.

The polymerization operation can be synthesized by a usual method such as batch polymerization or dropping polymerization. For example, an acid dissociable group-containing polymer can be obtained by dissolving a necessary monomer amount in an organic solvent and polymerizing in the presence of a radical polymerization initiator and a chain transfer agent.
As the polymerization solvent, an organic solvent capable of dissolving the monomer, the radical polymerization initiator, and the chain transfer agent is used. Examples of the organic solvent include ketone solvents, ether solvents, aprotic polar solvents, ester solvents, aromatic solvents, and linear or cyclic aliphatic solvents. Examples of the ketone solvent include methyl ethyl ketone and acetone. Examples of ether solvents include alkoxyalkyl ethers such as methoxymethyl ether, ethyl ether, tetrahydrofuran, and 1,4-dioxane. Examples of the aprotic polar solvent include dimethylformamide and dimethyl sulfoxide. Examples of ester solvents include alkyl acetates such as ethyl acetate and methyl acetate. Aromatic solvents include alkylaryl solvents such as toluene, xylene, and halogenated aromatic solvents such as chlorobenzene. Examples of the aliphatic solvent include hexane and cyclohexane.
The polymerization temperature is 20 to 120 ° C, preferably 50 to 110 ° C, more preferably 60 to 100 ° C. Although polymerization may be performed even in a normal air atmosphere, polymerization in an inert gas atmosphere such as nitrogen or argon is preferable. The molecular weight of the polymer can be adjusted by controlling the ratio between the monomer amount and the chain transfer agent amount.
The polymerization time is generally 0.5 to 144 hours, preferably 1 to 72 hours, more preferably 2 to 24 hours.

また、上記チオカルボニルチオ誘導体基を除去して使用することができる。連鎖移動剤由来の残基は、例えば下記（２）式で示すように、過剰なラジカル重合開始剤を利用して除去できる。

以下その処理方法について説明する。 The block copolymer obtained by the above living radical polymerization method has a residue derived from a chain transfer agent at the end of the molecular chain as shown by the following formula (1). In the present invention, a polymer having a thiocarbonylthio derivative group as a residue can be used as a block copolymer.

Further, it can be used after removing the thiocarbonylthio derivative group. The residue derived from the chain transfer agent can be removed by using an excess radical polymerization initiator, as shown, for example, by the following formula (2).

The processing method will be described below.

The end treatment is performed with a resin solution. As the solvent that can be used, those mentioned in the above polymerization operation can be used.
Usable radical polymerization initiators can be used as long as radicals can be generated under the conditions of polymer end group treatment. Radical generation conditions include high energy radiation such as heat, light, gamma rays or electron beams.
Specific examples of the radical polymerization initiator include initiators such as peroxides and azo compounds. Although not particularly limited, specific radical polymerization initiators include t-butyl hydroperoxide, t-butyl perbenzoate, benzoyl peroxide, 2,2′-azobis (2,4-dimethylvaleronitrile), 2, 2′-azobisisobutyronitrile (AIBN), 1,1′-azobis (cyclohexanecarbonitrile), dimethyl-2,2′-azobisisobutyrate (MAIB), dimethyl 2,2′-azobis (2 -Methyl propionate), benzoin ether, benzophenone and the like.
The polymer end treatment can be performed on the end product of the polymerization reaction after completion of the living radical polymerization reaction, or the polymer end treatment can be performed after the once produced polymer is purified.
In the terminal treatment reaction, the radical polymerization initiator can be added to the reaction vessel all at once or gradually. When adding gradually, you may divide and add in multiple times, or may add continuously.

When a thermal radical polymerization initiator is used, the temperature of the resin end group treatment reaction is about 20 to 200 ° C, preferably 40 to 150 ° C, more preferably 50 to 100 ° C. The reaction atmosphere is an inert atmosphere such as nitrogen or argon, or an air atmosphere. The pressure of the reaction can be normal pressure or increased pressure. The amount of the radical polymerization initiator is 1 to 800% mol, preferably 50 to 400% mol of the total number of moles of residues present in the polymer to be end-treated as the amount of radical generated by the radical polymerization initiator. Preferably, it can introduce | transduce so that it may become 100-300% mol, More preferably, it is 200-300% mol. If a more complete removal of the residue from the chain transfer agent is desired, an excess amount of radical polymerization initiator is used.
The reaction time for the terminal treatment is 0.5 to 72 hours, preferably 1 to 24 hours, more preferably 2 to 12 hours. Removal of residues such as thiogroups from the polymer ends is at least 50%, preferably at least 75%, more preferably 85%, even more preferably 95%. The end-treated polymer is replaced at the end with new radical species, such as radical initiator fragments derived from the radical initiator used in the end-treatment reaction. The resulting polymer has a new group at the end and can be used according to the application.
In addition, the polymer terminal treatment can remove a residue derived from a chain transfer agent by a method described in International Publication WO02 / 090397.

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

A radiation-sensitive resin composition is obtained by using the block copolymer as an acid-dissociable group-containing resin and combining with an acid generator that is a component that generates an acid upon irradiation with radiation.
The acid generator dissociates the acid dissociable groups present in the block copolymer by the action of the acid generated by exposure, and as a result, the exposed portion of the resist film becomes readily soluble in an alkali developer, and a positive resist. It has the effect | action which forms a pattern.
Examples of the acid generator in the present invention include onium salts such as sulfonium salts and iodonium salts, organic halogen compounds, and sulfone compounds such as disulfones and diazomethane sulfones.
Preferred examples of the acid generator include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1]. ] Triphenylsulfonium salt compounds such as hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate and triphenylsulfonium camphorsulfonate;

  4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2. 2.1] 4-cyclohexylphenyldiphenylsulfonium salt compounds such as hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate and 4-cyclohexylphenyldiphenylsulfonium camphorsulfonate;

  4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium 2- 4-methanesulfonylphenyl diphenylsulfonium salt compounds such as bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate and 4-methanesulfonylphenyldiphenylsulfonium camphorsulfonate;

  Diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2, Diphenyliodonium salt compounds such as 2-tetrafluoroethanesulfonate and diphenyliodonium camphorsulfonate;

  Bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, Bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t-butylphenyl) iodonium camphor Bis (4-tert-butylphenyl) iodonium salt compounds such as sulfonate;

  1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, (4-n-Butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium 2-bicyclo [2.2. 1] 1- (4-n-) such as hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphorsulfonate Butoxynaphthalen-1-yl) tetrahydrothiophenium salt compound;

  1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, (6-n-Butoxynaphthalen-2-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2. 1] 1- (6-n-) such as hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium camphorsulfonate Butoxynaphthalen-2-yl) tetrahydrothiophenium salt compound;

  1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, (3,5-Dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2. 1] 1- (3,5- such as hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium camphorsulfonate Dimethyl-4-hydroxyphenyl) tetrahydrothiol Salt compound;

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

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

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

Examples of such nitrogen-containing organic compounds include “tertiary amine compounds”, “amide group-containing compounds”, “quaternary ammonium hydroxide compounds”, “nitrogen-containing heterocyclic compounds”, and the like.
Examples of the “tertiary amine compound” include triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n. -Tri (cyclo) alkylamines such as octylamine, cyclohexyldimethylamine, tricyclohexylamine; alkanolamines such as triethanolamine, diethanolaniline; N, N, N ', N'-tetramethylethylenediamine, N, N , N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, 1,3-bis [1- (4-aminophenyl) -1-methylethyl] benzenetetramethylenediamine, 2,2-bis (4-amino) Phenyl) propane, 2- (3-aminophenyl) -2- (4-amino) Nophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4-aminophenyl) -2- (4-hydroxyphenyl) propane, 1,4-bis [1- (4-aminophenyl) -1-methylethyl] benzene, 1,3-bis [1- (4-aminophenyl) -1-methylethyl] benzene, bis (2-dimethylaminoethyl) ether, bis (2- Diethylaminoethyl) ether and the like.

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

Examples of the “quaternary ammonium hydroxide compound” include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-n-butylammonium hydroxide, and the like.
Examples of the “nitrogen-containing heterocyclic compound” include imidazoles such as imidazole, 4-methylimidazole, 1-benzyl-2-methylimidazole, 4-methyl-2-phenylimidazole, benzimidazole, 2-phenylbenzimidazole; In addition to piperazines such as piperazine and 1- (2-hydroxyethyl) piperazine, pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, 3-piperidino-1,2-propanediol, morpholine, 4-methylmorpholine, Examples include 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] octane.

  Of the above nitrogen-containing heterocyclic compounds, tertiary amine compounds, amide group-containing compounds, and nitrogen-containing heterocyclic compounds are preferable, and among the amide group-containing compounds, Nt-butoxycarbonyl group-containing amino compounds are preferable, including Among the nitrogen heterocyclic compounds, imidazoles are preferable.

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

In addition, an alicyclic additive having an acid dissociable group or an alicyclic additive not having an acid dissociable group is a component that further improves dry etching resistance, pattern shape, adhesion to a substrate, and the like. It is.
Examples of such alicyclic additives include 1-adamantanecarboxylic acid t-butyl, 1-adamantanecarboxylic acid t-butoxycarbonylmethyl, 1-adamantanecarboxylic acid α-butyrolactone ester, 1,3-adamantane dicarboxylic acid diester. -T-butyl, 1-adamantane acetate t-butyl, 1-adamantane acetate t-butoxycarbonylmethyl, 1,3-adamantanediacetate di-t-butyl, 2,5-dimethyl-2,5-di (adamantylcarbonyl) Adamantane derivatives such as oxy) hexane; deoxycholate t-butyl, deoxycholate t-butoxycarbonylmethyl, deoxycholate 2-ethoxyethyl, deoxycholate 2-cyclohexyloxyethyl, deoxycholate 3-oxocyclohexyl, Deoxychol Deoxycholic acid esters such as tetrahydropyranyl and deoxycholic acid mevalonolactone ester; lithocholic acid t-butyl, lithocholic acid t-butoxycarbonylmethyl, lithocholic acid 2-ethoxyethyl, lithocholic acid 2-cyclohexyloxyethyl, lithocholic acid Lithocholic acid esters such as 3-oxocyclohexyl, lithocholic acid tetrahydropyranyl, lithocholic acid mevalonolactone ester; dimethyl adipate, diethyl adipate, dipropyl adipate, di-n-butyl adipate, di-t-butyl adipate, etc. And alkyl carboxylic acid esters.
These alicyclic additives can be used alone or in admixture of two or more. The compounding quantity of an alicyclic additive is 50 mass parts or less normally with respect to 100 mass parts of block copolymers, Preferably it is 30 mass parts or less. In this case, when the blending amount of the alicyclic additive exceeds 50 parts by mass, the heat resistance as a resist tends to decrease.

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

Further, the sensitizer as an additive has an action of absorbing radiation energy and transmitting the energy to the acid generator, thereby increasing the amount of acid generated. The radiation-sensitive resin composition It has the effect of improving the apparent sensitivity.
Examples of such sensitizers include carbazoles, benzophenones, rose bengals, anthracenes, phenols and the like.
These sensitizers can be used alone or in admixture of two or more. The blending amount of the sensitizer is preferably 50 parts by mass or less with respect to 100 parts by mass of the block copolymer.
Furthermore, examples of additives other than those mentioned above include antihalation agents, adhesion assistants, storage stabilizers, antifoaming agents, and the like.
The radiation-sensitive resin composition of the present invention is usually dissolved in a solvent so that the total solid content concentration is usually 3 to 50% by mass, preferably 5 to 25% by mass. A composition solution is prepared by filtering through a filter having a pore size of about 0.2 μm.
Examples of the solvent used in the preparation of the composition solution include linear or branched ketones such as 2-pentanone, 2-hexanone, 2-heptanone, and 2-octanone; cyclopentanone, cyclohexanone, and the like. Cyclic ketones; propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate; 2-hydroxypropionate alkyls such as methyl 2-hydroxypropionate and ethyl 2-hydroxypropionate; In addition to alkyl 3-alkoxypropionates such as methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate and ethyl 3-ethoxypropionate,
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, n-butyl acetate, methyl pyruvate , Ethyl pyruvate, N-methylpyrrolidone, γ-butyrolactone and the like.

  These solvents may be used alone or in admixture of two or more, but propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, 2-heptanone, cyclohexanone, γ-butyrolactone, ethyl 2-hydroxypropionate, 3-ethoxy It is preferable to contain at least one selected from ethyl propionate. However, cyclohexanone is an effective solvent from the viewpoint of solubility, but it is preferable to avoid its use as much as possible because of its toxicity.

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

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

Hereinafter, the embodiments 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.
Each measurement and evaluation in Examples and Comparative Examples was performed as follows.
¹³ C-NMR:
“JNM-EX270” manufactured by JEOL Ltd. was used, and CDCL ₃ was used as a measurement solvent.
Mw and Mn:
Using a GPC column (2 G2000HXL, 1 G3000HXL, 1 G4000HXL) manufactured by Tosoh Corporation, monodisperse polystyrene was used as the standard under the analysis conditions of a flow rate of 1.0 ml / min, elution solvent tetrahydrofuran, and column temperature of 40 ° C. Measured by gel permeation chromatography (GPC).

sensitivity:
Regarding the examples and comparative examples, a substrate having a 77 nm ARC29A (Nissan Chemical) film formed on the wafer surface was used, and the composition was applied onto the substrate by spin coating, and the temperature was 110 ° C. and the time on the hot plate. A resist film having a thickness of 200 nm formed by PB under the conditions of 1 minute was exposed through a mask pattern using a full-field reduced projection exposure apparatus S306C (numerical aperture 0.75) manufactured by Nikon. After that, PEB was performed under conditions of a temperature of 110 ° C. and a time of 1 minute, then developed with a 2.38 mass% TMAH aqueous solution at 25 ° C. for 60 seconds, washed with water, and dried to form a positive resist pattern. did. At this time, an exposure amount formed in a one-to-one line-and-space with a line width of 100 nm is defined as an optimum exposure amount, and the optimum exposure amount is set as a line width formed through a one-to-one line-and-space mask having a dimension of 100 nm. “Sensitivity”.
resolution:
The dimension of the smallest resist pattern that can be resolved at the optimum exposure amount is defined as the resolution.
Density dependency:
The difference between the line width of the 100 nm line and space pattern and the line width of the 100 nm 1L10S pattern at the optimum exposure amount was defined as the density dependency.

The monomers used in each example and comparative example are shown below.

Example 1
Monomer solution (1) prepared by dissolving 26.56 g (50 mol%) of compound (M-1) and 22.67 g (45 mol%) of compound (M-2) in 30 g of 2-butanone, dimethyl 2,2 ′ A solution (2) obtained by dissolving 0.76 g of azobis (2-methylpropionate) in 14.40 g of 2-butanone, 0.76 g (5 mol%) of compound (M-3) and dimethyl 2,2′-azobis A monomer solution (3) in which 0.05 g of (2-methylpropionate) is dissolved in 5.0 g of 2-butanone is prepared.
Further, a 500 ml three-necked flask charged with 1.32 g of the chain transfer agent (CTA-3) and 7.23 g of 2-butanone is purged with nitrogen by a vacuum replacement method.
After purging with nitrogen, the contents in the three-necked flask were heated to 80 ° C. with stirring, and after 15 minutes, the monomer solution (1) and the monomer solution (2) were added over 3 hours using a feed pump. And dripped. Thereafter, the monomer solution (3) was added dropwise over 30 minutes, and the mixture was further stirred for 4 hours.
After completion of the polymerization, the polymerization solution was allowed to cool and then cooled to 30 ° C. or lower. Thereafter, 3.13 g of dimethyl 2,2′-azobis (2-methylpropionate) was added to the polymerization solution, heated to 80 ° C. and stirred for 3 hours. After completion of the reaction, the solution is allowed to cool, cooled to 30 ° C. or lower, poured into 400 g of isopropyl alcohol, and the precipitated white powder is filtered off.
The filtered white powder was washed twice with 200 g of isopropyl alcohol as a slurry, then filtered and dried at 60 ° C. for 17 hours to obtain a white powder polymer (35 g, yield 70%). ).
This polymer has Mw of 7600 and Mw / Mn of 1.3. As a result of ¹³ C-NMR analysis, the polymer is represented by compound (M-1), compound (M-2), and compound (M-3). The content ratio of each monomer-derived repeating unit was a copolymer of 52.9: 44.2: 2.9 (mol%). This polymer is referred to as a block copolymer (A-1).

Comparative Example 1
Monomer solution (1) prepared by dissolving 26.56 g (50 mol%) of compound (M-1) and 22.67 g (45 mol%) of compound (M-2) in 30 g of 2-butanone, dimethyl 2,2 ′ A solution (2) obtained by dissolving 0.76 g of azobis (2-methylpropionate) in 14.40 g of 2-butanone, 0.76 g (5 mol%) of compound (M-3) and dimethyl 2,2′-azobis A monomer solution (3) in which 0.05 g of (2-methylpropionate) is dissolved in 5.0 g of 2-butanone is prepared.
Further, a 500 ml three-necked flask charged with 1.32 g of the chain transfer agent (CTA-3) and 7.23 g of 2-butanone is purged with nitrogen by a vacuum replacement method.
After purging with nitrogen, the contents in the three-necked flask were heated to 80 ° C. with stirring. After 15 minutes, the monomer solution (1), the monomer solution (2) and the monomer solution (3) were simultaneously added. It dripped over 3 hours using the liquid feeding pump. Thereafter, the mixture was further stirred for 4 hours.
After completion of the polymerization, the polymerization solution was allowed to cool and then cooled to 30 ° C. or lower. Thereafter, 3.13 g of dimethyl 2,2′-azobis (2-methylpropionate) was added to the polymerization solution, heated to 80 ° C. and stirred for 3 hours. After completion of the reaction, the solution is allowed to cool, cooled to 30 ° C. or lower, poured into 400 g of isopropyl alcohol, and the precipitated white powder is filtered off.
The filtered white powder was washed twice with 200 g of isopropyl alcohol as a slurry, then filtered and dried at 60 ° C. for 17 hours to obtain a white powder polymer (34 g, yield 68%). ).
This polymer has Mw of 7700 and Mw / Mn of 1.3. As a result of ¹³ C-NMR analysis, the polymer is represented by compound (M-1), compound (M-2), and compound (M-3). The content ratio of each monomer-derived repeating unit was a copolymer having a ratio of 53.1: 44.1: 2.7 (mol%). This polymer is referred to as a random copolymer (R-1).

Example 2, Example 3 and Comparative Example 2
Using the copolymers obtained in Example 1 and Comparative Example 1, radiation-sensitive resin compositions were prepared with the formulations shown in Table 1. Various evaluation of the obtained radiation sensitive resin composition was performed. The evaluation results are shown in Table 1. In Table 1, the components used in addition to the resin component are as follows.
Acid generator (B)
B-1: 1- (4-n-butoxynaphthyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate B-2: Triphenylsulfonium nonafluoro-n-butanesulfonate acid diffusion controller (D)
D-1: Nt-butoxycarbonyl-4-hydroxypiperidine solvent (C)
C-1: Propylene glycol monomethyl ether acetate

  The radiation-sensitive resin composition of the present invention is useful as a chemically amplified resist that is sensitive to actinic rays, for example, far ultraviolet rays represented by KrF excimer laser (wavelength 248 nm) or ArF excimer laser (wavelength 193 nm). Since the resolution is high and the dependency on the density is excellent, it can be used extremely favorably in the manufacture of integrated circuit elements that are expected to be further miniaturized in the future.

Claims (5)

A block copolymer having a plurality of different partial constituents,
The plurality of different partial components contain a repeating unit having a lactone skeleton in the side chain and a partial component (A1) containing a repeating unit having an acid dissociable group, and a repeating unit having a cyano group in the side chain. A block copolymer, which is a partial component (A2), and has a mass average molecular weight in terms of standard polystyrene measured by gel permeation chromatography of 1,000 or more and 200,000 or less.   2. The block copolymer according to claim 1, wherein the partial constituent component (A2) is present at a block terminal of the block copolymer. The partial component (A1) and the partial component (A2) are copolymerized by living radical polymerization using a chain transfer agent represented by the following formula (X-1). The block copolymer according to claim 1 or 2.

(In the formula (X-1), R ^a represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, and Z represents 1 to 2 carbon atoms which may contain a substituent and a hetero atom. Represents a valent organic group.) The block copolymer according to claim 3, wherein Z is a substituent represented by the following formula (X-2).

(In the formula (X-2), R ^b , R ^c and R ^d each independently contain a hydrogen atom, a substituted or unsubstituted hydrocarbon group having 1 to 8 carbon atoms, or a substituted or unsubstituted heteroatom. This represents a hydrocarbon group having 1 to 8 carbon atoms or a ring containing a non-hydrogen atom having 3 to 20 constituent atoms formed by bonding any two of R ^b , R ^c and R ^d to each other. ) A radiation sensitive resin composition comprising an acid dissociable group-containing polymer and a radiation sensitive acid generator,
The radiation-sensitive resin composition, wherein the acid-dissociable group-containing polymer is the block copolymer according to claim 1 or 2.