KR101920999B1 - Polymer, negative resist composition, and pattern forming process - Google Patents

Abstract

[PROBLEMS] To provide a polymer suitable as a base resin of a negative type resist material having a high resolution and a small line edge roughness over conventional negative resist materials, a negative type resist material containing the same, and a pattern forming method using the same.
A polymer comprising 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) and having a weight average molecular weight of 1,000 to 500,000.

Description

POLYMER, NEGATIVE RESIST COMPOSITION, AND PATTERN FORMING PROCESS [0002]

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

With the increasingly high integration and high speed of LSI, the pattern rule is becoming finer. We are seeing mass production of 10-nm node logic devices and mass production of devices under 20 nm for DRAM. These are formed by double patterned ArF lithography. In addition, extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm is being studied.

On the other hand, the flash memory has been shifted to a three-dimensional memory which pulls up the miniaturization up to 15 nm and then increases the capacity by three-dimensional lamination. In this case, it is necessary to fabricate a superfine film having a thickness of more than 10 mu m for processing a multi-layered laminated film.

In ArF double patterning lithography, it is necessary to improve the alignment accuracy of a plurality of masks and to increase the precision of pattern dimensions, in addition to the increase in the number of masks. Even in the case of the mask for EUV lithography, it is necessary to form finer patterns and to make each pattern more accurate than that for ArF lithography.

In the production of a mask pattern, a resist pattern is formed by electron beam (EB) lithography. In order to improve the throughput of EB lithography, chemically amplified resists are generally used. As the chemically amplified resist, for example, a polymer obtained by substituting a part of a hydroxyl group of a polyhydroxystyrene with an acid labile group is used as a base resin, and an acid generator, a quencher for controlling diffusion of acid, a surfactant and an organic solvent are blended ≪ / RTI > The chemically amplified resist has merits of high sensitivity, but also has the drawback that resolution of the resolution and pattern is degraded by blurring of the image of the acid diffusion.

There is a problem that the resist pattern resolution by EB lithography is improved and the aspect ratio of the resist pattern is increased and consequently the pattern is collapsed due to the stress at the time of rinsing drying after development. In order to prevent this, the resist film is being thinned. In addition, in order to improve dry etching resistance, a polyhydroxystyrene substituted with an acid labile group and indene (Patent Document 1) or acenaphthylene (Patent Document 2) are copolymerized in order to improve dry etching resistance of the resist film A polymer-based positive resist has been proposed. The copolymerization of indene and acenaphthylene not only improved the dry etching resistance but also contributed to the control of acid diffusion, thereby contributing to an improvement in the resolution.

Even in the case of a negative resist, not only a negative type resist using a base polymer including a crosslinking agent or a crosslinking unit but also a negative type resist having a hydrophilicity lowered by a dehydration reaction with an acid, A polymer containing repeating units has been used (Patent Document 4).

In recent years, an oxide-based hard mask has been applied as a mask substrate, and it is no longer necessary to improve the dry etching resistance of the resist film. A resist having an excellent resolution has been demanded rather than improving dry etching resistance. In addition to improvement in resolution, in recent years, reduction of edge roughness (LER, LWR) has become important.

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-115630 Patent Document 2: Japanese Unexamined Patent Application Publication No. 2006-169302 Patent Document 3: Japanese Patent Application Laid-Open No. 2004-61794 Patent Document 4: JP-A-2013-164588

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a polymer suitable as a base resin of a negative type resist material having a high resolution and a small edge roughness over a conventional negative resist material, i-line, ArF excimer laser, EB, EUV exposure, and a pattern forming method using the same.

The inventors of the present invention have conducted intensive investigations to obtain a negative resist material having a high resolution and a small edge roughness as recently desired. As a result, a polymer containing a specific repeating unit is used as a base resin of a negative resist composition The present inventors have completed the present invention.

The polymer containing repeating units 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 required. Copolymerization of indene or acenaphthylene causes the main chain to become rigid and the glass transition point of the polymer to be high, thereby shortening the acid diffusion distance. The copolymer has higher acid diffusion control effect than the styrene copolymer. On the other hand, since indene and acenaphthylene are hydrophobic aromatic compounds, the hydrophilic part and the hydrophobic part are mixed in the polymer, and the solubility of the alkaline developer becomes uneven, causing swelling and deteriorating the edge roughness.

The copolymerized polymer of the hydroxystyrene and the coumarin partially substituted by the acid labile group described in Patent Document 3 has hydrophobicity lower than that of indene or acenaphthylene because coumarin has an ester group and suppresses swelling in an alkali developing solution, Thereby reducing the roughness. However, since the polymerizability of coumarin is low, it is difficult to uniformly introduce it into the polymer, which does not lead to reduction of edge roughness as desired.

The inventors of the present invention have conducted intensive investigations to further suppress acid diffusion and improve alkaline dissolution uniformity and reduce edge roughness. As a result, it has been found that a composition comprising a repeating unit derived from vinyl anthraquinone, a benzene ring bonded with a tertiary alkyl group containing a hydroxy group And a polymer containing a repeating unit derived from hydroxystyrene are used as a base resin of a negative type resist material, it is possible to obtain a high alkali dissolution rate contrast before and after exposure, a high effect of suppressing acid diffusion, It is possible to obtain a negative resist material which is excellent in pattern shape after exposure and good in edge roughness, particularly suitable for use in ultra LSI manufacture or as a material for forming fine patterns of a photomask.

Since vinyl anthraquinone is highly polymerizable similarly to styrene derivatives, it can be uniformly introduced into the polymer. Since it has two carbonyl groups and suitably has a hydrophilic property, the difference in hydrophilicity and hydrophobicity in the polymer is small, thereby making the alkali solubility uniform. The two carbonyl groups also have the property of controlling acid diffusion. By the above characteristics, a resist pattern with high resolution and small edge roughness can be obtained.

The negative resist material of the present invention is excellent in processability, and has a high dissolution contrast when used as a resist film, high effect of suppressing acid diffusion, high resolution, exposure margin, excellent process adaptability, The shape is good. Therefore, since they have excellent properties, they are very practical and are very effective as a material for forming a mask pattern for a resist material for a super LSI.

That is, the present invention provides the following polymer, negative type resist material and pattern forming method.

1. A polymer comprising 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) and having a weight average molecular weight of 1,000 to 500,000.

(Wherein, R ^A are each independently a hydrogen atom or a methyl group. R ¹ is a hydroxy group, a straight-chain or an alkoxy group, an acetoxy group having from 1 to 4 carbon atoms on the alkyl group, linear or branched having from 1 to 4 carbon atoms on the branch, or 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, Or a cyclic alkyl group, R ³ and R ⁴ may combine to form a ring with the carbon atoms 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 P and q are each independently 0 or 1. r is an integer of 0 to 4.)

2. A polymer comprising at least one member selected from the repeating units represented by the following formulas (f1) to (f3).

. (Wherein, R ^A are each, independently, a hydrogen atom or a methyl group, R ²¹ represents a single bond, phenylene group, -OR ³¹ -, or ^{-C (= O) -Z 1 -R} 31 - and, Z ¹ is -O- Or -NH-, and R ³¹ is an alkylene group having 1 to 6 carbon atoms, which is linear, branched or cyclic, a linear, branched or cyclic alkenylene group having 2 to 6 carbon atoms, or a phenylene group, Rf ¹ to Rf ⁴ are each independently a fluorine atom, a hydrogen atom or a trifluoromethyl group, but at least one of Rf ¹ to Rf ⁴ is a fluorine atom, R ²² to R ²⁹ each independently represents a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or a mercapto group, which may have a carbonyl group, an ester group or an ether group, It is a phenyl group. Y ¹ represents a single bond, or an ester group, an ether group or a lactone ring And optionally also a good linkage group having a carbon number of 1 ~ 12 Y ² is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenyl group, -OR ³² -. Or ^{-C (= O) -Z 2 -R} 32 - , and , Z ² is -O- or -NH-, 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 C2- An ether group or a hydroxyl group, and M ^- is a non-nucleophilic counter ion).

3. A negative type resist material comprising a base resin comprising 1 or 2 polymers.

4. A 2 or 3 negative type resist material which is a chemically amplified resist material further comprising an organic solvent and an acid generator.

5. The negative resist composition according to any one of 2 to 4, further comprising a basic compound.

6. A negative resist composition according to any one of claims 2 to 5, further comprising a surfactant.

7. A resist composition comprising: a step of applying a negative resist material of any one of items 2 to 6 onto a substrate to form a resist film by performing heat treatment; a step of exposing the resist film to high energy radiation; And a step of developing the film.

8. A method of forming a pattern in which the substrate is a photomask blank.

9. The pattern formation method of 7 or 8 wherein the high energy ray is ultraviolet ray having a wavelength of 180 to 400 nm.

10. The pattern formation method of claim 7, wherein the high energy beam is EB or EUV having a wavelength of 3 to 15 nm.

11. A photomask blank in which a negative resist material of any one of 3 to 6 is applied.

The negative resist material comprising the polymer of the present invention has a remarkably high alkaline dissolution rate contrast before and after exposure, has a high resolution, has a favorable pattern shape after exposure and good line edge roughness, can do. Therefore, it is particularly suitable as a material for forming fine patterns for ultra-LSI manufacture or photomask, pattern forming material for EB exposure, EUV exposure, and ArF excimer laser exposure. Further, the negative resist material of the present invention can be applied not only to lithography in the formation of a semiconductor circuit, but also to formation of a mask circuit pattern, formation of a micromachine, a thin film magnetic head circuit, and the like.

[Polymer]

The polymer of the present invention is a polymer comprising 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) (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 straight, branched or cyclic alkyl group of 1 to 6 carbon atoms, and R ³ and R ⁴ may bond to form a ring together with the carbon atoms 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; p and q are each independently 0 or 1; r is an integer of 0 to 4;

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

Monomers for obtaining the repeating unit b include, but are not limited to, those shown below. In the following formulas, R ^A is the same as the above.

Monomers for obtaining the repeating unit c include, but are not limited to, those shown below. In the following formulas, R ^A is the same as the above.

The polymer of the present invention may further contain a repeating unit d comprising a bonding group selected from a hydroxyl group, a lactone ring, an ether group, an ester group, a carbonyl group and a cyano group. Examples of the monomer giving the repeating unit d include, but are not limited to, the following. In the following formulas, R ^A is the same as the above.

In the case of a monomer containing a hydroxy group, the hydroxy group may be replaced with an acetal group which is easily deprotected by an acid such as an ethoxyethoxy group during the polymerization, deprotected by a weak acid and water after polymerization, And the alkali hydrolysis may be carried out after the polymerization by replacing the alkali by hydrolysis.

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 polymerizable olefins in which specific sulfonic acids are generated. Japanese Patent Laid-Open Publication No. 2006-178317 proposes a sulfonium salt in which a sulfonic acid is directly bonded to a main chain.

The preferable repeating unit f is preferably 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) (hereinafter referred to as repeating unit f3) represented by the following formula (f3). 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, -OR ³¹ - or -C (= O) -Z ¹ -R ³¹ -, Z ¹ is -O- or -NH-, and R ³¹ is a linear, An alkylene group having 1 to 6 carbon atoms which is cyclic, an alkenylene group having 2 to 6 carbon atoms, which is linear, branched or cyclic, or a phenylene group, and may contain a carbonyl group, an ester group, an ether group or a hydroxyl group. Rf ¹ to Rf ⁴ each independently represent a fluorine atom, a hydrogen atom or a trifluoromethyl group, but at least one of Rf ¹ to Rf ⁴ is a fluorine atom. R ²² to R ²⁹ each independently represents a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, which may contain a carbonyl group, an ester group or an ether group, , 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, -OR ³² - or -C (= O) -Z ² -R ³² -, Z ² is -O- or -NH- , 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 alkenylene group having 2 to 6 carbon atoms, and is a carbonyl group, an ester group, And may contain a hydroxy group. M ^- is an unconjugated counter ion.

Examples of the non-nucleophilic counter ion represented by M ^- include halide ions such as chloride ion and bromide ion, fluoroalkyl sulfone such as triflate, 1,1,1-trifluoroethanesulfonate and nonafluorobutane sulfonate Alkylsulfonates such as methanesulfonate, butanesulfonate, and the like; arylsulfonates such as benzylsulfonate, naphthylsulfonate, benzylsulfonate, 4-fluorobenzenesulfonate and 1,2,3,4,5-pentafluorobenzenesulfonate; Imide such as bis (trifluoromethylsulfonyl) imide, bis (perfluoroethylsulfonyl) imide and bis (perfluorobutylsulfonyl) imide, and tris (trifluoromethylsulfonyl) Methide, and tris (perfluoroethylsulfonyl) methide.

As the non-nucleophilic counter ion, a sulfonic acid ion represented by the following formula (K-1) wherein the? -Position is fluoro-substituted, a sulfonic acid ion represented by the following formula (K-2) And the like.

In the formula (K-1), R ¹⁰¹ is a hydrogen atom, a linear, branched or cyclic C1-30 alkyl group, a linear, branched or cyclic C2-30 acyl group, Or an aryl group having 6 to 20 carbon atoms or an aryloxy group and is preferably an ether group, an ester group, a carbonyl group, a lactone ring, a lactam ring, a sultone ring, an amino group, a sulfone group, , A carbonate group, a hydroxy group, a thiol group, a carboxyl group, a carbamate group, an amide group, and an imide group.

In the formula (K-2), R ¹⁰² represents a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms, a straight chain, branched or cyclic C2-30 acyl group, Or an aryl group having 6 to 20 carbon atoms or an aryloxy group and is preferably an ether group, an ester group, a carbonyl group, a lactone ring, a lactam ring, a sultone ring, an amino group, a sulfone group, , A carbonate group, a hydroxy group, a thiol group, a carboxyl group, a carbamate group, an amide group, and an imide group. 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 bonding an acid generator to the polymer main chain, it is possible to reduce the acid diffusion and prevent degradation of resolution due to clouding of acid diffusion. Further, the acid generator is uniformly dispersed, thereby improving the edge roughness.

The ratio of the repeating units a to d and f in the polymer of the present invention is preferably 0 <a <1.0, 0 <b <1.0, 0 <c <1.0, 0≤d≤0.7, and 0≤f≤0.3 , 0.03? A? 0.5, 0.05? B? 0.6, 0.1? C? 0.9, 0? D? 0.6 and 0? F? 0.25 are more preferable and 0.05? A? 0.4, 0.1? B? 0.5, ? 0.8, 0? D? 0.5 and 0? F? 0.2 are more preferable. When the repeating unit f is at least one selected from the repeating units f1 to f3, f = f1 + f2 + f3. Further, a + b + c + d + f? 1. For example, a + b + c = 1 means that the total amount of the repeating units a, b, and c in the polymer containing the repeating units a, b, and c is 100 mol% + c < 1 means that the total amount of the repeating units a, b and c is less than 100 mol% of the total repeating units and contains other repeating units other than the repeating units a, b and c.

The polymer of the present invention has a Mw of 1,000 to 500,000, preferably 2,000 to 30,000. If the Mw is too small, the resist material tends to have poor heat resistance. If the Mw is excessively large, the alkali solubility tends to deteriorate, and the patterning after the pattern formation tends to occur. Mw is a polystyrene reduced value measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

Further, when the polymer of the present invention has a large molecular weight distribution (Mw / Mn), there is a polymer having a low molecular weight or a high molecular weight, so that foreign matter may be seen on the pattern or the pattern may be deteriorated after exposure . The molecular weight distribution of the polymer of the present invention is 1.0 to 2.0, particularly 1.0 to 1.5, in order to obtain a resist material suitably used for a fine pattern dimension, since the influence of Mw and the molecular weight distribution tends to increase as the pattern rule becomes finer. It is preferable that the dispersion is (dispersion).

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

Examples of the organic solvent used in the polymerization include toluene, benzene, tetrahydrofuran, diethyl ether, and dioxane. Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2-azobis Nate), benzoyl peroxide, and lauroyl peroxide. The temperature at the time of polymerization is preferably 50 to 80 占 폚. The reaction time is preferably 2 to 100 hours, more preferably 5 to 20 hours.

When hydroxystyrene or hydroxyvinylnaphthalene is copolymerized, acetoxystyrene or acetoxyvinylnaphthalene is used instead of hydroxystyrene or hydroxyvinylnaphthalene. After the polymerization, the acetoxy group is deprotected by alkaline hydrolysis And hydroxystyrene or hydroxyvinylnaphthalene may be used.

As the base upon alkali hydrolysis, ammonia water, triethylamine and the like can be used. The reaction temperature is preferably -20 to 100 占 폚, more preferably 0 to 60 占 폚. 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 of a negative type resist material.

[Negative Resist Material]

The negative resist material of the present invention includes a base resin containing the above-mentioned polymer. When the polymer is used as a base resin of a negative resist composition, the base resin may be a blend of two or more polymers having different composition ratios, molecular weight distributions and molecular weights.

The negative resist material of the present invention preferably contains an organic solvent, an acid generator, a dissolving agent, a basic compound, a surfactant, and the like in appropriate combination depending on the purpose. By constituting the negative resist material in this manner, the dissolution rate of the polymer in the developing solution by the catalytic reaction is lowered in the exposure section, and therefore, a negative resist material with extremely high sensitivity can be obtained. Therefore, the resist film has high dissolution contrast and resolution, exposure latitude, excellent process adaptability, good pattern shape after exposure, excellent etching resistance, particularly, acid diffusion can be suppressed, It is very effective as a resist material for a super LSI. In particular, when a chemically amplified negative resist material containing an acid generator is incorporated and subjected to an acid catalysis reaction, the sensitivity can be made higher, and furthermore all properties are further improved, which is very useful.

Examples of the organic solvent include ketones such as cyclohexanone and methyl-2-n-amyl ketone described in paragraphs [0144] to [0145] of JP-A No. 2008-111103, 3-methoxybutanol, 3- Methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and other alcohols, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol mono Propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, 3- Esters such as ethyl ethoxypropionate, tert-butyl acetate, tert-butyl propionate and propylene glycol mono-tert-butyl ether acetate, lactones such as gamma -butyrolactone, There may be mentioned a mixed solvent. The blending amount of the organic solvent is preferably 50 to 10,000 parts by mass, 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 function as a chemically amplified negative resist material. Examples of the acid generator include a compound (photo-acid generator) that generates an acid in response to an actinic ray or radiation. The component of the photoacid generator may be any compound that generates an acid by irradiation with high energy radiation. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate acid generators, and the like. These may be used singly or in combination of two or more. Specific examples of the acid generator include those described in paragraphs [0122] to [0142] of Japanese Patent Application Laid-Open No. 2008-111103. The blending amount of the acid generator is preferably 0.01 to 100 parts by mass, more preferably 0.1 to 80 parts by mass, per 100 parts by mass of the base resin.

The negative resist material of the present invention may contain a solubilizer agent. By mixing the dissolving agent, the difference in dissolution rate between the exposed portion and the unexposed portion can be further increased, and the resolution can be further improved. Specific examples of the dissolving agent yesterday include those described in paragraphs [0155] to [0178] of JP-A No. 2008-122932. The blending amount of the dissolving agent is preferably 0 to 50 parts by mass, more preferably 0 to 40 parts by mass with respect to 100 parts by mass of the base resin.

The negative resist material of the present invention may contain a basic compound. By mixing a basic compound, for example, the diffusion rate of the acid in the resist film can be suppressed to further improve the resolution. Examples of the basic compound include primary, secondary or tertiary amine compounds described in paragraphs [0146] to [0164] of Japanese Patent Laid-Open Publication No. 2008-111103, especially hydroxyl group, ether group, ester group, lactone ring, cyano group , An amine compound having a sulfonic acid ester group, and a compound having a carbamate group described in Japanese Patent No. 3790649. As a basic compound, a polymer type quencher described in JP-A-2008-239918 is also exemplified. This can increase the squareness of the resist after the pattern by orienting it on the surface of the resist after coating. The polymer-type retainer also has an effect of preventing film thickness reduction and rounding of the pattern top when a protective film for liquid immersion exposure is applied. The blending amount of the basic compound is preferably from 0 to 100 parts by mass, more preferably from 0.001 to 50 parts by mass, per 100 parts by mass of the base resin.

The negative resist material of the present invention may contain a surfactant. By adding the surfactant, the applicability 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 No. 2008-111103. The blending amount of the surfactant is preferably 0 to 10 parts by mass, more preferably 0.0001 to 5 parts by mass, per 100 parts by mass of the base resin.

The resist material of the present invention may further contain acetylene alcohols. Examples of the acetylene alcohols include those described in paragraphs [0179] to [0182] of JP-A-2008-122932. The blending amount of acetylene alcohols is preferably 0 to 5 parts by mass based on 100 parts by mass of the base resin.

[Pattern formation method]

When the negative resist material of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied.

For example, the negative resist material of the present invention can be used as a substrate for producing integrated circuits (Si, SiO ₂ , SiN, SiON, TiN, WSi, BPSG, SOG, organic anti- Such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coat, etc., on the surface of the substrate (e.g., CrON, MoSi ₂ or SiO ₂ ) This is prebaked on a hot plate, preferably at 60 to 150 ° C for 10 seconds to 30 minutes, more preferably at 80 to 120 ° C for 30 seconds to 20 minutes. Subsequently, a desired pattern is exposed to high-energy radiation such as ultraviolet rays, far ultraviolet rays, EB, EUV, X-rays, soft X-rays, excimer lasers,? -Rays or synchrotron radiation through a predetermined mask or directly. The exposure dose is preferably about 1 to 200 mJ / cm 2, particularly about 10 to 100 mJ / cm 2, or about 0.1 to 100 μC / cm 2, particularly about 0.5 to 50 μC / cm 2. Then, post-exposure baking (PEB) is performed on a hot plate, preferably at 60 to 150 ° C for 10 seconds to 30 minutes, more preferably at 80 to 120 ° C for 30 seconds to 20 minutes.

An antistatic film based on polythiophene or polyaniline may be provided on the resist film, or a top coat film other than the antistatic film may be formed.

(TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetraethylammonium hydroxide (TPAH), and the like are further added, preferably in an amount of 0.1 to 10 mass%, more preferably 2 to 5 mass% A dip method, a puddle method, a spraying method (spraying method), or the like using a developer of an aqueous alkaline solution such as tetrabutylammonium hydroxide (TBAH) or tetrabutylammonium hydroxide (TBAH) for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes spraying) method, a target negative pattern is formed on the substrate, in which the light-irradiated portion is not dissolved in the developer and the unexposed portion is dissolved. Further, the resist material of the present invention is particularly suitable for fine patterning by EB, EUV, soft X-ray, X-ray,? -Ray and synchrotron radiation even in a high energy beam.

In general, TEAH, TPAH and TBAH having longer alkyl chains than the widely used TMAH aqueous solution have an effect of reducing the swelling in the development and preventing the collapse of the pattern. As the TMAH developing solution, an aqueous solution of 2.38% by mass is most widely used. This corresponds to 0.26 N, and it is preferable that the aqueous solution of TEAH, TPAH or TBAH is also the same. The concentrations of TEAH, TPAH, and TBAH, which are 0.26 N, are 3.84 mass%, 5.31 mass%, and 6.78 mass%, respectively.

In a pattern of 32 nm or less resolved by EB or EUV, a phenomenon occurs in which lines become twisted, lines stick together, or lines sticking together collapse. This is thought to be caused by the swelling of the swelled lines in the developing solution. The swelled line contains developer and is so soft as a sponge that it is easy to fall due to the stress of the rinse. Developing solutions containing long alkyl chains of TEAH, TPAH and TBAH have the effect of preventing swelling and preventing pattern collapse.

[Example]

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. Here, the weight average molecular weight (Mw) is measured by GPC using polystyrene conversion using THF as a solvent. The 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

3.5 g of 2-vinyl anthraquinone, 4.1 g of monomer 1, 7.2 g of 4-hydroxystyrene, and 20 g of THF as a solvent were added to a 2 L flask. The reaction vessel was cooled to -70 占 폚 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) as a polymerization initiator was added, the temperature was raised to 60 ° C, and the reaction was carried out for 15 hours. The reaction solution was concentrated to ½ and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The resulting white solid was separated by filtration and dried under reduced pressure at 60 DEG C to obtain polymer 1. The composition of the polymer 1 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn by GPC.

[Example 1-2] Synthesis of polymer 2

3.5 g of 2-vinyl anthraquinone, 4.1 g of monomer 2, 7.8 g of 4-hydroxystyrene and 40 g of THF as a solvent were added to a 2 L flask. The reaction vessel was cooled to -70 占 폚 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 DEG C, and the reaction was carried out for 15 hours. The reaction solution was concentrated to ½ and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The obtained white solid was separated by filtration 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 by GPC.

[Example 1-3] Synthesis of polymer 3

3.5 g of 2-vinyl anthraquinone, 5.1 g of monomer 3, 4.2 g of 4-hydroxystyrene, 3.6 g of methacrylic acid-4-hydrophenyl and 40 g of THF as a solvent were added to a 2 L flask. The reaction vessel was cooled to -70 占 폚 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 DEG C, and the reaction was carried out for 15 hours. The reaction solution was concentrated to ½ and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The obtained white solid was separated by filtration and dried under reduced pressure at 60 캜 to obtain polymer 3. The composition of polymer 3 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn by GPC.

[Example 1-4] Synthesis of polymer 4

3.5 g of 2-vinyl anthraquinone, 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 were added to a 2 L flask. The reaction vessel was cooled to -70 占 폚 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 DEG C, and the reaction was carried out for 15 hours. The reaction solution was concentrated to ½ and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The resulting white solid was separated by filtration and dried under reduced pressure at 60 캜 to obtain polymer 4. The composition of polymer 4 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn by GPC.

[Example 1-5] Synthesis of polymer 5

4.5 g of 2-vinyl anthraquinone, 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 were added to a 2 L flask. The reaction vessel was cooled to -70 占 폚 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 DEG C, and the reaction was carried out for 15 hours. The reaction solution was concentrated to ½ and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The obtained white solid was separated by filtration and dried under reduced pressure at 60 占 폚 to obtain polymer 5. The composition of polymer 5 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn by GPC.

[Example 1-6] Synthesis of polymer 6

2 L flask, 2-vinyl-anthraquinone 4.5 g, 1 4.9 g monomer, methacrylic acid-4-hydroxyphenyl 5.3 g, methacrylic acid 3-oxo-2,7-dioxa-tricyclo [4.2.1.0 ^{4 , 8} ] nonan-9-yl, 7.4 g of PAG monomer 3 and 40 g of THF as a solvent. The reaction vessel was cooled to -70 占 폚 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 DEG C, and the reaction was carried out for 15 hours. The reaction solution was concentrated to ½ and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The obtained white solid was separated by filtration and dried under reduced pressure at 60 DEG 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 by GPC.

[Example 1-7] Synthesis of polymer 7

2.3 g of 2-vinyl anthraquinone, 4.9 g of monomer 1, 5.3 g of methacrylic acid-4-hydroxyphenyl, 2.0 g of? -Methylene-? -Butyrolactone, 7.4 g of PAG monomer 4, 40 g of THF were added. The reaction vessel was cooled to -70 占 폚 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 DEG C, and the reaction was carried out for 15 hours. The reaction solution was concentrated to ½ and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The resulting white solid was separated by filtration and dried under reduced pressure at 60 캜 to obtain polymer 7. The composition of the polymer 7 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn by GPC.

[Comparative Example 1-1] Synthesis of comparative polymer 1

Synthesis was conducted in the same manner as in Example 1-1 except that acenaphthylene (2.3 g) was used instead of 2-vinyl anthraquinone to obtain Comparative Polymer 1. The composition of comparative polymer 1 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw / Mn by GPC.

[2] Preparation of Negative Resist Material

[Examples 2-1 to 2-9, Comparative Example 2-1]

A solution obtained by dissolving each component in the composition shown in Table 1 was filtered with a filter having a size of 0.2 mu m by using a solvent in which 100 ppm of surfactant FC-4430 manufactured by 3M Co., Ltd. was dissolved as a surfactant, and a negative type resist material was prepared.

The components in Table 1 are as follows.

Polymers 1 to 7: The polymers obtained in Examples 1-1 to 1-7

Comparative polymer 1: The polymer obtained in Comparative Example 1

· Organic solvents: PGMEA (propylene glycol monomethyl ether acetate)

CyH (cyclohexanone)

· Acid generator: PAG1 (see the following structural formula)

· Basic compound: Kureta 1 (see the following formula)

[3] EB lithography evaluation

Each of the negative resist materials prepared in Examples 2-1 to 2-9 and Comparative Example 2-1 was spin-coated on a Si substrate having a diameter of 6 inches by using Clean Track Mark 5 (manufactured by Tokyo Electron Co., Ltd.) Coated and baked on a hot plate at 110 DEG C for 60 seconds to prepare a 100 nm resist film. To this, HL-800D (manufactured by Hitachi, Ltd.) was used, and the film was drawn in a vacuum chamber at an HV voltage of 50 kV.

Immediately after drawing, PEB was immediately performed on a hot plate at a temperature shown in Table 1 for 60 seconds using a clean track Mark 5 (manufactured by Tokyo Electron Co., Ltd.), and puddle development was performed for 30 seconds with a 2.38 mass% aqueous TMAH solution, Pattern.

The obtained resist pattern was evaluated as follows.

The line edge roughness (LER) of 100 nmLS was measured by SEM with the minimum dimension as the resolution at the exposure amount for resolving the line and space of 100 nm at 1: 1.

The results are 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 had sufficient resolution and sensitivity, and the LER was reduced.

Claims (11)

A polymer comprising 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) and having a weight average molecular weight of 1,000 to 500,000.

(Wherein, R ^A are each independently a hydrogen atom or a methyl group. R ¹ is a hydroxy group, a straight-chain or an alkoxy group, an acetoxy group having from 1 to 4 carbon atoms on the alkyl group, linear or branched having from 1 to 4 carbon atoms on the branch, or 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, Or a cyclic alkyl group, R ³ and R ⁴ may combine to form a ring with the carbon atoms 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 P and q are each independently 0 or 1. r is an integer of 0 to 4.) The polymer according to claim 1, further comprising at least one member selected from the repeating units represented by the following formulas (f1) to (f3).

. (Wherein, R ^A are each, independently, a hydrogen atom or a methyl group, R ²¹ represents a single bond, phenylene group, -OR ³¹ -, or ^{-C (= O) -Z 1 -R} 31 - and, Z ¹ is -O- Or -NH-, and R ³¹ is an alkylene group having 1 to 6 carbon atoms, which is linear, branched or cyclic, a linear, branched or cyclic alkenylene group having 2 to 6 carbon atoms, or a phenylene group, Rf ¹ to Rf ⁴ are each independently a fluorine atom, a hydrogen atom or a trifluoromethyl group, but at least one of Rf ¹ to Rf ⁴ is a fluorine atom, R ²² to R ²⁹ each independently represents a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or a mercapto group, which may have a carbonyl group, an ester group or an ether group, Y ¹ is a single bond, or 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 phenylene group, a fluorinated phenylene group, -OR ³² -, or -C (= O) -Z ² -R ³² - , Z ² is -O- or -NH-, 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 C2- An ether group or a hydroxyl group, and M ^- is a non-nucleophilic counter ion). A negative resist composition comprising a base resin containing the polymer according to claim 1. 4. The negative resist composition according to claim 3, which further comprises a chemical amplification resist material comprising an organic solvent and an acid generator. The negative resist composition according to claim 3, further comprising a basic compound. The negative resist composition according to claim 3, further comprising a surfactant. A method for forming a resist film, comprising the steps of applying the negative resist composition described in claim 3 onto a substrate to form a resist film by performing a heat treatment, and a step of forming a resist film by exposing the substrate to ultraviolet light, deep ultraviolet light, electron beam (EB) , A step of exposing the resist film to a high energy line selected from an excimer laser,? -Ray or synchrotron radiation, and a step of developing the resist film exposed using a developer. 8. The method of claim 7, wherein the substrate is a photomask blank. The pattern forming method according to claim 7, wherein the high energy ray is an ultraviolet ray having a wavelength of 180 to 400 nm. The pattern forming method according to claim 7, wherein the high energy ray is an electron beam or an extreme ultraviolet ray having a wavelength of 3 to 15 nm. A photomask blank coated with the negative resist material according to claim 3.