JP2017222832A - Polymer, negative resist material, and pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer suitable as a base resin of negative resist materials, with small line edge roughness, at higher resolution than that of conventional negative resist materials, and negative resist materials containing the same, and a pattern forming method using the same.SOLUTION: A polymer contains a repeating unit represented by the formula (a), a repeating unit represented by the formula (b), and a repeating unit represented by the formula (c) and has a weight average molecular weight of 1,000-500,000.SELECTED DRAWING: None

Description

  The present invention relates to a polymer, a negative resist material, and a pattern forming method.

  With the high integration and high speed of LSI, pattern rule miniaturization is progressing rapidly. Mass production of 10 nm node logic devices and mass production of devices of 20 nm or less are imminent. These are formed by double patterning ArF lithography. Further, extreme ultraviolet (EUV) lithography having a wavelength of 13.5 nm is being studied.

  On the other hand, the flash memory has been shifted to a three-dimensional memory that increases the capacity by three-dimensional stacking after pulling down to 15 nm. In this case, an ultra-thick film processing technique exceeding 10 μm for processing a multi-layered laminated film is required.

  In ArF double patterning lithography, as the number of masks increases, it is necessary to improve the alignment accuracy of a plurality of masks and increase the accuracy of pattern dimensions. Even in the mask for EUV lithography, it is necessary to form a finer pattern than in the case of ArF lithography and to increase the accuracy of each pattern.

  In manufacturing a mask pattern, a resist pattern is formed by electron beam (EB) lithography. In order to improve the throughput of EB lithography, a chemically amplified resist is generally used. Examples of the chemically amplified resist include, as a base resin, a polymer obtained by substituting a part of the hydroxy group of polyhydroxystyrene with an acid labile group, and an acid generator, a quencher that controls acid diffusion, and a surfactant. And what mix | blended the organic solvent is mentioned. Chemically amplified resists have the advantage of higher sensitivity, but also have the disadvantage that resolution and pattern accuracy are reduced due to blurring of the image of acid diffusion.

  Along with the improvement of the resolution of the resist pattern by EB lithography, the aspect ratio of the resist pattern increases, and this causes a problem that the pattern collapses due to the stress at the time of rinse drying after development. In order to prevent this, the resist film has been made thinner. At the same time, it is necessary to improve the dry etching resistance. In order to improve the dry etching resistance of the resist film, polyhydroxystyrene substituted with an acid labile group, indene (Patent Document 1) and acenaphthylene (Patent Document 2) are used. Copolymerized polymer-based positive resists have been proposed. Copolymerization of indene and acenaphthylene not only improved dry etching resistance, but also had the advantage of controlling acid diffusion, contributing to improved resolution.

  Even in the case of a negative resist, not only a negative resist using a base polymer containing a crosslinking agent or a crosslinking unit, but also a negative resist whose hydrophilicity decreases due to a dehydration reaction with an acid, a repeating unit derived from indene or acenaphthylene. A polymer containing was used (Patent Document 4).

  In recent years, an oxide film type hard mask has been applied as a mask substrate, and it has become unnecessary to improve the resistance of the resist film to excessive dry etching. There is a growing demand for resists with higher resolution than improving dry etching resistance. In recent years, in addition to improving resolution, it has become important to reduce edge roughness (LER, LWR). It is coming.

JP 2004-115630 A JP 2006-169302 A JP 2004-61794 A JP 2013-164588 A

  The present invention has been made in view of the above circumstances, a polymer suitable as a base resin for a negative resist material having a higher resolution and a smaller edge roughness than a conventional negative resist material, a negative resist material using the polymer, In particular, an object of the present invention is to provide a negative resist material suitable for i-line, ArF excimer laser, EB, and EUV exposure, and a pattern forming method using the same.

  As a result of intensive investigations to obtain a negative resist material having high resolution and low edge roughness, which has been recently demanded, the present inventors have found that a polymer containing a specific repeating unit includes a negative resist material. It was found that it was extremely effective when used as a base resin, and the present invention was completed.

  A polymer containing a repeating unit derived from indene or acenaphthylene described in Patent Document 4 has excellent acid diffusion control and reduced edge roughness, but further improvement in performance is necessary. By copolymerizing indene and acenaphthylene, the main chain becomes stiff and the glass transition point of the polymer is increased, thereby shortening the acid diffusion distance. The copolymer has a higher acid diffusion control effect than the styrene copolymer. On the other hand, since indene and acenaphthylene are hydrophobic aromatic compounds, hydrophilic and hydrophobic parts are mixed in the polymer, so that the solubility of the alkaline developer becomes non-uniform and causes swelling, resulting in deterioration of edge roughness. It becomes a factor.

  The copolymer of hydroxystyrene partially substituted with an acid labile group described in Patent Document 3 and coumarin has a lower hydrophobicity than indene or acenaphthylene because of the presence of coumarin, and alkali development. Reduces edge roughness by suppressing swelling in the liquid. However, it is difficult to uniformly introduce the coumarin into the polymer due to the low polymerizability of coumarin, and this does not lead to the reduction of edge roughness as intended.

  As a result of intensive studies to further suppress acid diffusion and improve alkali dissolution uniformity and reduce edge roughness, the present inventors have found that a repeating unit derived from vinyl anthraquinone, a hydroxy group-containing tertiary alkyl group, By using a polymer containing a repeating unit containing a bonded benzene ring and a repeating unit derived from hydroxystyrene as the base resin of a negative resist material, the alkali dissolution rate contrast before and after exposure is high, and the effect of suppressing acid diffusion is high. The present inventors have found that a negative resist material having high resolution and good pattern shape and edge roughness after exposure, particularly suitable for ultra LSI manufacturing or as a fine pattern forming material for a photomask can be obtained.

  Since vinyl anthraquinone has high polymerizability like a styrene derivative, it can be uniformly introduced into the polymer. Since it has two carbonyl groups and is moderately hydrophilic, the difference between the hydrophilicity and the hydrophobicity in the polymer is small, thereby making the alkali solubility uniform. The two carbonyl groups also have the property of controlling acid diffusion. With the above characteristics, a resist pattern with high resolution and low edge roughness can be obtained.

  The negative resist material of the present invention has a particularly high dissolution contrast when used as a resist film, a high effect of suppressing acid diffusion, a high resolution, an exposure margin, and excellent process adaptability, The pattern shape after exposure is good. Therefore, since it has these excellent characteristics, it is extremely practical and is very effective as a resist material mask pattern forming material for VLSI.

（式中、Ｒ^Aは、それぞれ独立に、水素原子又はメチル基である。Ｒ¹は、ヒドロキシ基、直鎖状若しくは分岐状の炭素数１〜４のアルキル基、直鎖状若しくは分岐状の炭素数１〜４のアルコキシ基、アセトキシ基、又はハロゲン原子を表す。Ｒ²及びＲ⁵は、それぞれ独立に、直鎖状若しくは分岐状の炭素数１〜６のアルキル基、又はハロゲン原子である。Ｒ³及びＲ⁴は、それぞれ独立に、炭素数１〜６の直鎖状、分岐状又は環状のアルキル基であり、Ｒ³とＲ⁴とが結合して、これらが結合する炭素原子と共に環を形成していてもよい。Ｘ¹及びＸ²は、それぞれ独立に、単結合又はエステル基である。ｍは、１又は２である。ｐ及びｑは、それぞれ独立に、０又は１である。ｒは、０〜４の整数である。）
２．更に、下記式（ｆ１）〜（ｆ３）で表される繰り返し単位から選ばれる少なくとも１種を含む１のポリマー。

（式中、Ｒ^Aは、それぞれ独立に、水素原子又はメチル基である。Ｒ²¹は、単結合、フェニレン基、−Ｏ−Ｒ³¹−、又は−Ｃ(＝Ｏ)−Ｚ¹−Ｒ³¹−であり、Ｚ¹は、−Ｏ−又は−ＮＨ−であり、Ｒ³¹は、直鎖状、分岐状若しくは環状の炭素数１〜６のアルキレン基、直鎖状、分岐状若しくは環状の炭素数２〜６のアルケニレン基、又はフェニレン基であり、カルボニル基、エステル基、エーテル基又はヒドロキシ基を含んでいてもよい。Ｒｆ¹〜Ｒｆ⁴は、それぞれ独立に、フッ素原子、水素原子又はトリフルオロメチル基であるが、Ｒｆ¹〜Ｒｆ⁴のうち少なくとも１つはフッ素原子である。Ｒ²²〜Ｒ²⁹は、それぞれ独立に、カルボニル基、エステル基若しくはエーテル基を含んでいてもよい直鎖状、分岐状若しくは環状の炭素数１〜１２のアルキル基、炭素数６〜１２のアリール基、炭素数７〜２０のアラルキル基、又はメルカプトフェニル基である。Ｙ¹は、単結合、又はエステル基、エーテル基又若しくはラクトン環を含んでいてもよい炭素数１〜１２の連結基である。Ｙ²は、単結合、メチレン基、エチレン基、フェニレン基、フッ素化フェニレン基、−Ｏ−Ｒ³²−、又は−Ｃ(＝Ｏ)−Ｚ²−Ｒ³²−であり、Ｚ²は、−Ｏ−又は−ＮＨ−であり、Ｒ³²は、直鎖状、分岐状若しくは環状の炭素数１〜６のアルキレン基、フェニレン基、又は直鎖状、分岐状若しくは環状の炭素数２〜６のアルケニレン基であり、カルボニル基、エステル基、エーテル基又はヒドロキシ基を含んでいてもよい。Ｍ^-は、非求核性対向イオンである。）
３．１又は２のポリマーを含むベース樹脂を含むネガ型レジスト材料。
４．更に、有機溶剤及び酸発生剤を含む化学増幅レジスト材料である２又は３のネガ型レジスト材料。
５．更に、塩基性化合物を含む２〜４のいずれかのネガ型レジスト材料。
６．更に、界面活性剤を含む２〜５のいずれかのネガ型レジスト材料。
７．２〜６のいずれかのネガ型レジスト材料を基板上に塗布し、加熱処理をしてレジスト膜を形成する工程と、前記レジスト膜を高エネルギー線で露光する工程と、現像液を用いて露光したレジスト膜を現像する工程とを含むパターン形成方法。
８．前記基板が、フォトマスクブランクである７のパターン形成方法。
９．前記高エネルギー線が、波長１８０〜４００ｎｍの紫外線である７又は８のパターン形成方法。
１０．前記高エネルギー線が、ＥＢ又は波長３〜１５ｎｍのＥＵＶである７又は８のパターン形成方法。
１１．３〜６のいずれかのネガ型レジスト材料を塗布したフォトマスクブランク。 That is, the present invention provides the following polymer, negative resist material, and pattern formation method.
1. A repeating unit represented by the following formula (a), a repeating unit represented by the following formula (b), and a repeating unit represented by the following formula (c) have a weight average molecular weight of 1,000 to 500,000. Is a polymer.

(In the formula, each R ^A is independently a hydrogen atom or a methyl group. R ¹ is a hydroxy group, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched group, and Represents an alkoxy group having 1 to 4 carbon atoms, an acetoxy group, or a halogen atom, and R ² and R ⁵ are each independently a linear or branched alkyl group having 1 to 6 carbon atoms or a halogen atom. R ³ and R ⁴ are each independently a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and R ³ and R ⁴ are bonded together with the carbon atom to which they are bonded. X ¹ and X ² are each independently a single bond or an ester group, m is 1 or 2, and p and q are each independently 0 or 1; R is an integer from 0 to 4)
2. Furthermore, 1 polymer containing at least 1 sort (s) chosen from the repeating unit represented by following formula (f1)-(f3).

(In the formula, each R ^A independently represents a hydrogen atom or a methyl group. R ²¹ represents a single bond, a phenylene group, —O—R ³¹ —, or —C (═O) —Z ¹ —R ^31. -, Z ¹ is -O- or -NH-, and R ³¹ is a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, linear, branched or cyclic carbon. It is an alkenylene group of 2 to 6 or a phenylene group, and may contain a carbonyl group, an ester group, an ether group or a hydroxy group, and Rf ^{1 to} Rf ⁴ each independently represents a fluorine atom, a hydrogen atom or a trimethyl group. Although it is a fluoromethyl group, at least one of Rf ^{1 to} Rf ⁴ is a fluorine atom, and each of R ^{22 to} R ²⁹ independently represents a straight chain which may contain a carbonyl group, an ester group or an ether group. , Branched or cyclic C 1-12 An alkyl group, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or a mercaptophenyl group, and Y ¹ may contain a single bond, an ester group, an ether group, or a lactone ring. A good linking group having 1 to 12 carbon atoms Y ² is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, —O—R ³² —, or —C (═O) —Z ^2. —R ³² —, Z ² is —O— or —NH—, and R ³² is a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, a phenylene group, or a linear group. A branched or cyclic alkenylene group having 2 to 6 carbon atoms, which may contain a carbonyl group, an ester group, an ether group or a hydroxy group, and M ⁻ is a non-nucleophilic counterion.)
3. A negative resist material containing a base resin containing the polymer 1 or 2.
4). Furthermore, the negative resist material of 2 or 3 which is a chemically amplified resist material containing an organic solvent and an acid generator.
5. Furthermore, the negative resist material in any one of 2-4 containing a basic compound.
6). Furthermore, the negative resist material in any one of 2-5 containing surfactant.
A step of applying a negative resist material according to any one of 7.2 to 6 on a substrate and performing a heat treatment to form a resist film; a step of exposing the resist film with a high energy beam; and a developer. And a step of developing the exposed resist film.
8). 7. The pattern forming method according to 7, wherein the substrate is a photomask blank.
9. The pattern forming method according to 7 or 8, wherein the high energy ray is an ultraviolet ray having a wavelength of 180 to 400 nm.
10. The pattern forming method according to 7 or 8, wherein the high energy ray is EB or EUV having a wavelength of 3 to 15 nm.
The photomask blank which apply | coated the negative resist material in any one of 11.3-6.

  The negative resist material containing the polymer of the present invention has a significantly high alkali dissolution rate contrast before and after exposure, high resolution, good pattern shape after exposure and line edge roughness, and in particular, acid resistance. The diffusion rate can be suppressed. Therefore, it is particularly suitable as a pattern forming material for ultra LSI manufacturing or photomask fine pattern forming material, EUV exposure, ArF excimer laser exposure. The negative resist material of the present invention can be applied not only to lithography in semiconductor circuit formation, but also to mask circuit pattern formation, micromachine, thin film magnetic head circuit formation, and the like.

[polymer]
The polymer of the present invention has a repeating unit represented by the following formula (a) (hereinafter referred to as repeating unit a), a repeating unit represented by the following formula (b) (hereinafter referred to as repeating unit b), and the following. It contains a repeating unit represented by the formula (c) (hereinafter referred to as repeating unit c) and has a weight average molecular weight (Mw) of 1,000 to 500,000.

In the formula, each R ^A is independently a hydrogen atom or a methyl group. R ¹ represents a hydroxy group, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, an acetoxy group, or a halogen atom. R ² and R ⁵ are each independently a linear or branched alkyl group having 1 to 6 carbon atoms, or a halogen atom. R ³ and R ⁴ are each independently a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and R ³ and R ⁴ are bonded to each other together with the carbon atom to which they are bonded. May be formed. X ¹ and X ² are each independently a single bond or an ester group. m is 1 or 2. p and q are each independently 0 or 1. r is an integer of 0-4.

Examples of the monomer for obtaining the repeating unit a include, but are not limited to, those shown below.

Examples of the monomer for obtaining the repeating unit b include, but are not limited to, those shown below. In the following formula, R ^A is the same as described above.

Examples of the monomer for obtaining the repeating unit c include, but are not limited to, those shown below. In the following formula, R ^A is the same as described above.

The polymer of the present invention may further contain a repeating unit d containing an adhesive group selected from a hydroxy group, a lactone ring, an ether group, an ester group, a carbonyl group and a cyano group. Monomers that give the repeating unit d include, but are not limited to, those shown below. In the following formula, R ^A is the same as described above.

  In the case of a monomer containing a hydroxy group, the hydroxy group may be replaced with an acetal group that can be easily deprotected with an acid such as an ethoxyethoxy group at the time of polymerization, and then deprotected with a weak acid and water after the polymerization, or an acetyl group, Substitution with a formyl group, pivaloyl group or the like, and alkali hydrolysis may be performed after polymerization.

  The polymer of the present invention may contain a repeating unit f derived from an onium salt containing a polymerizable olefin. JP-A-4-230645, JP-A-2005-84365, and JP-A-2006-045311 propose sulfonium salts and iodonium salts having a polymerizable olefin that generates a specific sulfonic acid. Japanese Patent Application Laid-Open No. 2006-178317 proposes a sulfonium salt in which a sulfonic acid is directly bonded to the main chain.

As preferred repeating unit f, a repeating unit represented by the following formula (f1) (hereinafter referred to as repeating unit f1), a repeating unit represented by the following formula (f2) (hereinafter referred to as repeating unit f2), and And a repeating unit represented by the following formula (f3) (hereinafter referred to as a repeating unit f3). Note that the repeating units f1 to f3 may be used singly or in combination of two or more.

In the formula, each R ^A is independently a hydrogen atom or a methyl group. R ²¹ is a single bond, a phenylene group, —O—R ³¹ —, or —C (═O) —Z ¹ —R ³¹ —, Z ¹ is —O— or —NH—, and R ³¹ Is a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, a linear, branched or cyclic alkenylene group having 2 to 6 carbon atoms, or a phenylene group, a carbonyl group, an ester group, An ether group or a hydroxy group may be contained. Rf ^{1 to} Rf ⁴ are each independently a fluorine atom, a hydrogen atom, or a trifluoromethyl group, and at least one of Rf ^{1 to} Rf ⁴ is a fluorine atom. R ^{22 to} R ²⁹ are each independently a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms and aryl having 6 to 12 carbon atoms, which may contain a carbonyl group, an ester group or an ether group. Group, an aralkyl group having 7 to 20 carbon atoms, or a mercaptophenyl group. Y ¹ is a single bond or a linking group having 1 to 12 carbon atoms which may contain an ester group, an ether group or a lactone ring. Y ² is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, —O—R ³² —, or —C (═O) —Z ² —R ³² —, and Z ² is — O— or —NH—, and R ³² is a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, a phenylene group, or a linear, branched or cyclic group having 2 to 6 carbon atoms. It is an alkenylene group and may contain a carbonyl group, an ester group, an ether group or a hydroxy group. M ⁻ is a non-nucleophilic counter ion.

Non-nucleophilic counter ions represented by M ⁻ include halide ions such as chloride ions and bromide ions, fluoroalkyl sulfonates such as triflate, 1,1,1-trifluoroethanesulfonate, and nonafluorobutanesulfonate. Aryl sulfonates such as tosylate, benzene sulfonate, 4-fluorobenzene sulfonate, 1,2,3,4,5-pentafluorobenzene sulfonate, alkyl sulfonates such as mesylate and butane sulfonate, bis (trifluoromethylsulfonyl) imide, bis ( Examples thereof include imide acids such as perfluoroethylsulfonyl) imide and bis (perfluorobutylsulfonyl) imide, and methide acids such as tris (trifluoromethylsulfonyl) methide and tris (perfluoroethylsulfonyl) methide.

The non-nucleophilic counter ion further includes a sulfonate ion in which the α-position represented by the following formula (K-1) is fluoro-substituted, and the α and β-positions represented by the following formula (K-2) are fluoro. Examples include substituted sulfonate ions.

In formula (K-1), R ¹⁰¹ represents a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms, a linear, branched or cyclic acyl group having 2 to 30 carbon atoms. A linear, branched or cyclic alkenyl group having 2 to 20 carbon atoms, aryl group having 6 to 20 carbon atoms, or aryloxy group, ether group, ester group, carbonyl group, lactone ring, lactam ring, sultone A ring, amino group, sulfone group, sulfonate group, carbonate group, hydroxy group, thiol group, carboxyl group, carbamate group, amide group, and imide group may be contained.

In formula (K-2), ^R102 represents a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms, a linear, branched or cyclic acyl group having 2 to 30 carbon atoms. A linear, branched or cyclic alkenyl group having 2 to 20 carbon atoms, aryl group having 6 to 20 carbon atoms, or aryloxy group, ether group, ester group, carbonyl group, lactone ring, lactam ring, sultone A ring, amino group, sulfone group, sulfonate group, carbonate group, hydroxy group, thiol group, carboxyl group, carbamate group, amide group, and imide group may be contained. R ¹⁰³ is a hydrogen atom, a methyl group, an ethyl group or a trifluoromethyl group.

  The repeating unit f functions as an acid generator. By binding an acid generator to the polymer main chain, acid diffusion can be reduced, and degradation of resolution due to blurring of acid diffusion can be prevented. Further, the edge roughness is improved by uniformly dispersing the acid generator.

  In the polymer of the present invention, the ratio of the repeating units a to f is 0 <a <1.0, 0 <b <1.0, 0 <c <1.0, 0 ≦ d ≦ 0.7, 0, respectively. ≦ e ≦ 0.7 and 0 ≦ f ≦ 0.3 are preferred, 0.03 ≦ a ≦ 0.5, 0.05 ≦ b ≦ 0.6, 0.1 ≦ c ≦ 0.9, 0 ≦ d ≦ 0.6, 0 ≦ e ≦ 0.6, and 0 ≦ f ≦ 0.25, more preferably 0.05 ≦ a ≦ 0.4, 0.1 ≦ b ≦ 0.5, 0.2 ≦ c ≦ More preferred are 0.8, 0 ≦ d ≦ 0.5, 0 ≦ e ≦ 0.5, and 0 ≦ f ≦ 0.2. When the repeating unit f is at least one selected from repeating units f1 to f3, f = f1 + f2 + f3. Further, a + b + c + d + e + f ≦ 1. For example, a + b + c = 1 means that in a polymer containing repeating units a, b and c, the total amount of repeating units a, b and c is 100 mol% in all repeating units, and a + b + c <1 Indicates that the total amount of the repeating units a, b and c is less than 100 mol% in all repeating units and contains other repeating units in addition to the repeating units a, b and c.

  The polymer of the present invention has an Mw of 1,000 to 500,000, preferably 2,000 to 30,000. If Mw is too small, the resist material is inferior in heat resistance, and if it is too large, the alkali solubility is lowered, and the trailing phenomenon tends to occur after pattern formation. In addition, Mw is a polystyrene conversion measured value by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

  Further, when the molecular weight distribution (Mw / Mn) is wide in the polymer of the present invention, there are low molecular weight and high molecular weight polymers, so that foreign matter is seen on the pattern after exposure or the shape of the pattern deteriorates. There is a risk of Since the influence of Mw and molecular weight distribution tends to increase as the pattern rule becomes finer, the molecular weight distribution of the polymer of the present invention is 1.0 to 1.0 in order to obtain a resist material suitably used for fine pattern dimensions. It is preferably a narrow dispersion of 2.0, particularly 1.0 to 1.5.

  In order to synthesize the polymer of the present invention, for example, a desired monomer among the monomers giving the repeating units a to f may be heated and polymerized by adding a radical polymerization initiator in an organic solvent.

  Examples of the organic solvent used at the time of polymerization include toluene, benzene, tetrahydrofuran, diethyl ether, dioxane and the like. As polymerization initiators, 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2-azobis (2-methylpropionate) ), Benzoyl peroxide, lauroyl peroxide, and the like. The temperature during the polymerization is preferably 50 to 80 ° C. The reaction time is preferably 2 to 100 hours, more preferably 5 to 20 hours.

  When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene is used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy group is deprotected by alkali hydrolysis to hydroxystyrene or hydroxyvinyl. Naphthalene may be used.

  Ammonia water, triethylamine, etc. can be used as the base during the alkali hydrolysis. Moreover, reaction temperature becomes like this. Preferably it is -20-100 degreeC, More preferably, it is 0-60 degreeC. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

  The polymer of the present invention is suitable as a base resin for a negative resist material.

[Negative resist material]
The negative resist material of the present invention contains a base resin containing the aforementioned polymer. When the polymer is used as a base resin for a negative resist material, the base resin may be a blend of two or more polymers having different composition ratios, molecular weight distributions, and molecular weights.

  It is preferable that the negative resist material of the present invention further contains an organic solvent, an acid generator, a dissolution controller, a basic compound, a surfactant, and the like in appropriate combination according to the purpose. By constructing the negative resist material in this manner, the dissolution rate of the polymer in the developing solution is accelerated by a catalytic reaction in the exposed portion, so that an extremely sensitive negative resist material can be obtained. Therefore, the resist film has high dissolution contrast and resolution, exposure margin, excellent process adaptability, good pattern shape after exposure, and better etching resistance, especially suppressing acid diffusion Therefore, the difference in density between the layers is small, and from these, the practicality is high and the resist material for VLSI can be made very effective. In particular, a chemically amplified negative resist material containing an acid generator and utilizing an acid-catalyzed reaction can be made more highly sensitive and more excellent in properties and extremely useful. .

  Examples of the organic solvent include ketones such as cyclohexanone and methyl-2-n-amylketone described in paragraphs [0144] to [0145] of JP-A-2008-111103, 3-methoxybutanol, 3-methyl- Alcohols such as 3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether , Ethers such as diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, pyrubin Esters such as ethyl, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol mono tert-butyl ether acetate, lactones such as γ-butyrolactone, And a mixed solvent thereof. The blending amount of the organic solvent is preferably 50 to 10,000 parts by mass and more preferably 100 to 5,000 parts by mass with respect to 100 parts by mass of the base resin.

  The negative resist material of the present invention may contain an acid generator in order to make the chemically amplified negative resist material function. Examples of the acid generator include compounds that generate an acid in response to actinic rays or radiation (photoacid generator). The component of the photoacid generator may be any compound that generates an acid upon irradiation with high energy rays. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, and the like. These can be used alone or in combination of two or more. Specific examples of the acid generator include those described in paragraphs [0122] to [0142] of JP-A-2008-111103. 0.01-100 mass parts is preferable with respect to 100 mass parts of base resins, and, as for the compounding quantity of an acid generator, 0.1-80 mass parts is more preferable.

  The negative resist material of the present invention may contain a dissolution control agent. By blending the dissolution control agent, the difference in dissolution rate between the exposed area and the unexposed area can be further increased, and the resolution can be further improved. Specific examples of the dissolution control agent include those described in paragraphs [0155] to [0178] of JP-A-2008-122932. 0-50 mass parts is preferable with respect to 100 mass parts of base resins, and, as for the compounding quantity of a dissolution control agent, 0-40 mass parts is more preferable.

  The negative resist material of the present invention may contain a basic compound. By blending the basic compound, for example, the acid diffusion rate in the resist film can be suppressed and the resolution can be further improved. Examples of basic compounds include primary, secondary or tertiary amine compounds described in paragraphs [0146] to [0164] of JP-A-2008-111103, particularly hydroxy groups, ether groups, ester groups, and lactones. Examples thereof include amine compounds having a ring, a cyano group, and a sulfonic acid ester group, and compounds having a carbamate group described in Japanese Patent No. 3790649. Examples of the basic compound also include a polymer-type quencher described in JP-A-2008-239918. This can enhance the rectangularity of the patterned resist by orienting it on the coated resist surface. The polymer quencher also has an effect of preventing pattern film loss and pattern top rounding when a protective film for immersion exposure is applied. 0-100 mass parts is preferable with respect to 100 mass parts of base resins, and, as for the compounding quantity of a basic compound, 0.001-50 mass parts is more preferable.

The negative resist material of the present invention may contain a surfactant. By blending the surfactant, the coating property of the resist material can be further improved or controlled.
Specific examples of the surfactant include those described in paragraphs [0165] to [0166] of JP-A-2008-111103. 0-10 mass parts is preferable with respect to 100 mass parts of base resins, and, as for the compounding quantity of surfactant, 0.0001-5 mass parts is more preferable.

The resist material of the present invention can further contain acetylene alcohols.
Examples of acetylene alcohols include those described in paragraphs [0179] to [0182] of JP-A-2008-122932. As for the compounding quantity of acetylene alcohol, 0-5 mass parts is preferable with respect to 100 mass parts of base resins.

[Pattern formation method]
When the negative resist material of the present invention is used for manufacturing various integrated circuits, a known lithography technique can be applied.

For example, the negative resist material of the present invention is applied to an integrated circuit manufacturing substrate (Si, SiO ₂ , SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflection film, etc.) or a mask circuit manufacturing substrate (Cr , CrO, CrON, MoSi ₂ , SiO _2, etc.) by a suitable coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc., so that the coating film thickness becomes 0.01-2 μm. Apply to. This is preferably pre-baked on a hot plate at 60 to 150 ° C. for 10 seconds to 30 minutes, more preferably at 80 to 120 ° C. for 30 seconds to 20 minutes. Next, the target pattern is exposed through a predetermined mask or directly with high energy rays such as ultraviolet rays, far ultraviolet rays, EB, EUV, X-rays, soft X-rays, excimer laser, γ rays, synchrotron radiation and the like. The exposure dose, 1 to 200 mJ / cm ² or so, in particular 10 to 100 mJ / cm ² or so, or 0.1~100μC / cm ² or so, be exposed to particularly a 0.5~50μC / cm ² of about preferable. Next, post exposure baking (PEB) is preferably performed on a hot plate at 60 to 150 ° C. for 10 seconds to 30 minutes, more preferably at 80 to 120 ° C. for 30 seconds to 20 minutes.

  A polythiophene or polyaniline-based antistatic film may be provided on the resist film, or another topcoat film may be formed.

  Further, preferably 0.1 to 5% by mass, more preferably 2 to 10% by mass of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium. Conventional methods such as dip method, paddle method, spray method, etc., using a developer of an aqueous alkaline solution such as hydroxide (TBAH) for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes. As a result of the development, an intended negative pattern is formed on the substrate, in which the portion irradiated with light is not dissolved in the developer and the portion not exposed is dissolved. The resist material of the present invention is particularly suitable for fine patterning by EB, EUV, soft X-ray, X-ray, γ-ray, and synchrotron radiation among high energy rays.

  TEAH, TPAH, and TBAH, which have a longer alkyl chain than the TMAH aqueous solution that is widely used in general, have the effect of reducing swelling during development and preventing pattern collapse. As the TMAH developer, a 2.38% by mass aqueous solution is most widely used. This corresponds to 0.26N, and it is preferable that the TEAH, TPAH or TBAH aqueous solution has the same normality. The concentrations of TEAH, TPAH and TBAH to be 0.26N are 3.84% by mass, 5.31% by mass and 6.78% by mass, respectively.

  In a pattern of 32 nm or less that is resolved by EB or EUV, a phenomenon occurs in which the lines are twisted, the lines are stuck together, or the stuck lines are tilted. This is thought to be because the lines swollen and swollen in the developer are stuck together. Since the swollen line is soft like a sponge containing a developer, it tends to collapse due to the stress of rinsing. A developer containing TEAH, TPAH and TBAH having a long alkyl chain has an effect of preventing swelling and preventing pattern collapse.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. The weight average molecular weight (Mw) is a measured value in terms of polystyrene by GPC using THF as a solvent. In addition, monomers 1 to 3 and PAG monomers 1 to 4 used in the following examples are as follows.

[1] Synthesis of Polymer [Example 1-1] Synthesis of Polymer 1 To a 2 L flask was added 3.5 g of 2-vinylanthraquinone, 4.1 g of monomer 1, 7.2 g of 4-hydroxystyrene, and 20 g of THF as a solvent. . The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After raising the temperature to room temperature, 1.2 g of azobisisobutyronitrile (AIBN) was added as a polymerization initiator, and the temperature was raised to 60 ° C., followed by reaction for 15 hours. When this reaction solution was concentrated to 1/2 and added to a mixed solvent of 1 L of methanol and 0.1 L of water, a white solid precipitated. The obtained white solid was filtered off and dried under reduced pressure at 60 ° C. to obtain polymer 1. The composition of Polymer 1 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn were confirmed by GPC.

[Example 1-2] Synthesis of polymer 2 To a 2 L flask, 3.5 g of 2-vinylanthraquinone, 4.1 g of monomer 2, 7.8 g of 4-hydroxystyrene, and 40 g of THF as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After raising the temperature to room temperature, 1.2 g of AIBN was added as a polymerization initiator, and the temperature was raised to 60 ° C. and reacted for 15 hours. When this reaction solution was concentrated to 1/2 and added to a mixed solvent of 1 L of methanol and 0.1 L of water, a white solid precipitated. The obtained white solid was filtered off and dried under reduced pressure at 60 ° C. to obtain polymer 2. The composition of Polymer 2 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn were confirmed by GPC.

[Example 1-3] Synthesis of polymer 3 In a 2 L flask, 3.5 g of 2-vinylanthraquinone, 5.1 g of monomer 3, 4.2 g of 4-hydroxystyrene, 3.6 g of methacrylic acid-4-hydrophenyl, and a solvent As a solution, 40 g of THF was added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After raising the temperature to room temperature, 1.2 g of AIBN was added as a polymerization initiator, and the temperature was raised to 60 ° C. and reacted for 15 hours. When this reaction solution was concentrated to 1/2 and added to a mixed solvent of 1 L of methanol and 0.1 L of water, a white solid precipitated. The obtained white solid was filtered off and dried under reduced pressure at 60 ° C. to obtain polymer 3. The composition of Polymer 3 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn were confirmed by GPC.

[Example 1-4] Synthesis of polymer 4 To a 2 L flask was added 3.5 g of 2-vinylanthraquinone, 4.9 g of monomer 1, 4.8 g of 4-hydroxystyrene, 6.8 g of PAG monomer 1, and 40 g of THF as a solvent. did. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After raising the temperature to room temperature, 1.2 g of AIBN was added as a polymerization initiator, and the temperature was raised to 60 ° C. and reacted for 15 hours. When this reaction solution was concentrated to 1/2 and added to a mixed solvent of 1 L of methanol and 0.1 L of water, a white solid precipitated. The obtained white solid was filtered off and dried under reduced pressure at 60 ° C. to obtain polymer 4. The composition of polymer 4 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn were confirmed by GPC.

[Example 1-5] Synthesis of polymer 5 To a 2 L flask was added 4.5 g of 2-vinylanthraquinone, 4.9 g of monomer 1, 4.8 g of 4-hydroxystyrene, 5.9 g of PAG monomer 2, and 40 g of THF as a solvent. did. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After raising the temperature to room temperature, 1.2 g of AIBN was added as a polymerization initiator, and the temperature was raised to 60 ° C. and reacted for 15 hours. When this reaction solution was concentrated to 1/2 and added to a mixed solvent of 1 L of methanol and 0.1 L of water, a white solid precipitated. The obtained white solid was filtered off and dried under reduced pressure at 60 ° C. to obtain polymer 5. The composition of polymer 5 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn were confirmed by GPC.

[Example 1-6] Synthesis of polymer 6 In a 2 L flask, 4.5 g of 2-vinylanthraquinone, 4.9 g of monomer 1, 5.3 g of methacrylic acid-4-hydroxyphenyl, 3-oxo-2,7-methacrylic acid. Dioxatricyclo [4.2.1.0 ^4,8 ] nonan-9-yl 2.2 g, PAG monomer 3 7.4 g, and THF 40 g as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After raising the temperature to room temperature, 1.2 g of AIBN was added as a polymerization initiator, and the temperature was raised to 60 ° C. and reacted for 15 hours. When this reaction solution was concentrated to 1/2 and added to a mixed solvent of 1 L of methanol and 0.1 L of water, a white solid precipitated. The obtained white solid was filtered off and dried under reduced pressure at 60 ° C. to obtain polymer 6. The composition of polymer 6 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn were confirmed by GPC.

[Example 1-7] Synthesis of polymer 7 In a 2 L flask, 2.3 g of 2-vinylanthraquinone, 4.9 g of monomer 1, 5.3 g of methacrylic acid-4-hydroxyphenyl, 2.0 g of α-methylene-γ-butyrolactone. 7.4 g of PAG monomer 4 and 40 g of THF as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After raising the temperature to room temperature, 1.2 g of AIBN was added as a polymerization initiator, and the temperature was raised to 60 ° C. and reacted for 15 hours. When this reaction solution was concentrated to 1/2 and added to a mixed solvent of 1 L of methanol and 0.1 L of water, a white solid precipitated. The obtained white solid was filtered off and dried under reduced pressure at 60 ° C. to obtain polymer 7. The composition of polymer 7 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn were confirmed by GPC.

Comparative Example 1-1 Synthesis of Comparative Polymer 1 Comparative polymer 1 was obtained by synthesis in the same manner as in Example 1-1 except that 2.3 g of acenaphthylene was used instead of 2-vinylanthraquinone. The composition of Comparative Polymer 1 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn were confirmed by GPC.

[2] Preparation of negative resist material [Examples 2-1 to 2-9, Comparative Example 2-1]
A negative resist material obtained by filtering a solution in which each component of the composition shown in Table 1 is dissolved in a solvent in which 100 ppm of surfactant FC-4430 manufactured by 3M as a surfactant is dissolved, through a 0.2 μm size filter. Was prepared.
Each component in Table 1 is as follows.
Polymers 1-7: Polymers obtained in Examples 1-1 to 1-7 Comparative polymer 1: Polymer obtained in Comparative Example 1 Organic solvent: PGMEA (propylene glycol monomethyl ether acetate)
CyH (cyclohexanone)
・ Acid generator: PAG1 (see the following structural formula)
・ Basic compound: Quencher 1 (see the following structural formula)

[3] EB Lithography Evaluation Each negative resist material prepared in Examples 2-1 to 2-9 and Comparative Example 2-1 was placed on a Si substrate having a diameter of 6 inches φ on a clean track Mark 5 (Tokyo Electron Limited). ), And pre-baked on a hot plate at 110 ° C. for 60 seconds to prepare a 100 nm resist film. For this, drawing in a vacuum chamber was performed at an HV voltage of 50 kV using HL-800D manufactured by Hitachi, Ltd.
Immediately after drawing, PEB is performed for 60 seconds at a temperature shown in Table 1 on a hot plate using a clean truck Mark 5 (manufactured by Tokyo Electron Ltd.), and paddle development is performed for 30 seconds with a 2.38 mass% TMAH aqueous solution. A negative pattern was obtained.
The obtained resist pattern was evaluated as follows.
The minimum dimension at the exposure amount for resolving 100 nm line and space at 1: 1 was taken as the resolving power, and the line edge roughness (LER) of 100 nm LS was measured by SEM.
The results are also shown in Table 1.

  From the results shown in Table 1, it was found that the resist material using the polymer of the present invention has sufficient resolution and sensitivity, and LER is reduced.

Claims (11)

A repeating unit represented by the following formula (a), a repeating unit represented by the following formula (b), and a repeating unit represented by the following formula (c) have a weight average molecular weight of 1,000 to 500,000. Is a polymer.

(In the formula, each R ^A is independently a hydrogen atom or a methyl group. R ¹ is a hydroxy group, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched group, and Represents an alkoxy group having 1 to 4 carbon atoms, an acetoxy group, or a halogen atom, and R ² and R ⁵ are each independently a linear or branched alkyl group having 1 to 6 carbon atoms or a halogen atom. R ³ and R ⁴ are each independently a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and R ³ and R ⁴ are bonded together with the carbon atom to which they are bonded. X ¹ and X ² are each independently a single bond or an ester group, m is 1 or 2, and p and q are each independently 0 or 1; R is an integer from 0 to 4) Furthermore, the polymer of Claim 1 containing at least 1 sort (s) chosen from the repeating unit represented by following formula (f1)-(f3).

(In the formula, each R ^A independently represents a hydrogen atom or a methyl group. R ²¹ represents a single bond, a phenylene group, —O—R ³¹ —, or —C (═O) —Z ¹ —R ^31. -, Z ¹ is -O- or -NH-, and R ³¹ is a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, linear, branched or cyclic carbon. It is an alkenylene group of 2 to 6 or a phenylene group, and may contain a carbonyl group, an ester group, an ether group or a hydroxy group, and Rf ^{1 to} Rf ⁴ each independently represents a fluorine atom, a hydrogen atom or a trimethyl group. Although it is a fluoromethyl group, at least one of Rf ^{1 to} Rf ⁴ is a fluorine atom, and each of R ^{22 to} R ²⁹ independently represents a straight chain which may contain a carbonyl group, an ester group or an ether group. , Branched or cyclic C 1-12 An alkyl group, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or a mercaptophenyl group, and Y ¹ may contain a single bond, an ester group, an ether group, or a lactone ring. A good linking group having 1 to 12 carbon atoms Y ² is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, —O—R ³² —, or —C (═O) —Z ^2. —R ³² —, Z ² is —O— or —NH—, and R ³² is a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, a phenylene group, or a linear group. A branched or cyclic alkenylene group having 2 to 6 carbon atoms, which may contain a carbonyl group, an ester group, an ether group or a hydroxy group, and M ⁻ is a non-nucleophilic counterion.)   A negative resist material comprising a base resin comprising the polymer according to claim 1.   4. The negative resist material according to claim 2, which is a chemically amplified resist material further comprising an organic solvent and an acid generator.   Furthermore, the negative resist material of any one of Claims 2-4 containing a basic compound.   Furthermore, the negative resist material of any one of Claims 2-5 containing surfactant.   Applying the negative resist material according to any one of claims 2 to 6 on a substrate and performing a heat treatment to form a resist film, exposing the resist film with a high energy beam, and developing And a step of developing a resist film exposed using a liquid.   The pattern forming method according to claim 7, wherein the substrate is a photomask blank.   The pattern forming method according to claim 7, wherein the high energy ray is ultraviolet light having a wavelength of 180 to 400 nm.   The pattern forming method according to claim 7 or 8, wherein the high energy beam is an electron beam or extreme ultraviolet rays having a wavelength of 3 to 15 nm.   The photomask blank which apply | coated the negative resist material of any one of Claims 3-6.