JPWO2013141015A1 - Composition for forming resist underlayer film for EUV lithography - Google Patents

Abstract

The present invention provides a resist underlayer film forming composition for EUV that can improve resist sensitivity and roughness of a resist pattern. A composition for forming a resist underlayer film for lithography comprising a polymer having a structure represented by the following formula (1) at the end and an organic solvent. Wherein X is a phenyl group substituted with at least one selected from the group consisting of a halogen atom, a hydroxy group, and a linear or branched alkoxy group having 1 to 6 carbon atoms. Represents a naphthyl group or an anthracenyl group, and v represents 0 or 1.) [Selection] None

Description

INDUSTRIAL APPLICABILITY The present invention is useful for forming a resist underlayer film between a substrate and a resist film formed thereon in order to obtain a resist pattern having a desired shape in a lithography process in the process of manufacturing a semiconductor device. Relates to the composition. In particular, the present invention relates to a composition for forming a resist underlayer film suitable for a lithography process using exposure with extreme ultraviolet rays (hereinafter abbreviated as EUV) having a wavelength of 13 nm to 14 nm.

Currently, EUV lithography is strongly required to improve the output of an EUV exposure light source in an EUV exposure apparatus. When the output of the exposure light source is low, the exposure time for forming the target resist pattern increases, and the wafer processing time per unit time also increases, which may cause a reduction in production efficiency in the manufacturing process. For this reason, the resist is required to accurately form a desired resist pattern with a lower energy exposure amount.

In order to form a target resist pattern with a low exposure amount, it is necessary that a photochemical reaction generated by irradiating the resist with EUV light can be generated with lower energy. Thus, in order for the photochemical reaction of the resist to occur at a low exposure amount, it is necessary to have a high response to EUV light. Therefore, a resist material in EUV lithography is strongly required to improve the photoresponsiveness (sensitivity) of such a resist.

In addition, in the case of EUV lithography, the pattern line width to be formed is 32 nm or less, and in order to accurately transfer the resist pattern to the base substrate, Line Width Roughness, which is an index representing fluctuation of the resist pattern to be formed. The demand for (LWR) and Line Edge Roughness (LER), which is an index representing fluctuation of the side wall of the resist pattern, becomes more severe. When the formed resist pattern shape is a skirt shape or a shape where adjacent patterns are connected without being separated, or when the formed resist pattern fluctuates in a specific direction, when observed from above the pattern The values of LWR and LER increase, which adversely affects the dimensional control of the resist pattern to be formed. Therefore, a resist material used for EUV lithography is strongly required to reduce such fluctuation (roughness) of the resist pattern.

So far, a resist underlayer film forming composition with reduced outgas generation has been disclosed as a material for forming a resist underlayer film oriented to EUV lithography (Patent Document 1). Also, a resist underlayer film forming composition containing a reaction product of a diglycidyl ester compound and an acid dianhydride is disclosed, although it is not a material specified for EUV exposure (Patent Document 2). However, these resist underlayer film forming compositions do not exemplify resist underlayer film forming compositions obtained by capping the polymer ends, and do not describe the effects of improving the sensitivity and roughness of the resist.

International Publication No. 2010/061774 International Publication No. 2009/104685

As techniques for improving resist sensitivity and roughness in EUV lithography, attempts have been made to optimize the chemical structure or additive components of the resin contained in the resist material, and to optimize the exposure conditions and development conditions in the resist formation process. In addition, there is a method for controlling the chemical state of the interface between the resist and the resist underlayer film. That is, in a positive resist, when the chemical state at the interface between the resist and the resist underlayer film is a base state, the resulting resist pattern shape tends to be a trailing shape, and the roughness of the resist pattern tends to increase. Therefore, it can be said that the resist sensitivity deteriorates because it is necessary to irradiate a higher exposure amount in order to correct the tailing shape and form a resist pattern having a target dimension. On the other hand, when the chemical state of the interface between the resist and the resist underlayer film is in an acidic state, the resist pattern shape can be suppressed from becoming a trailing shape, and a resist pattern having a desired dimension can be formed with a lower exposure amount. It can be said that the resist sensitivity is improved.

Therefore, an object of the present invention is to provide a resist underlayer film forming composition in which the surface state of a resist underlayer film is modified to an acidic state by an EUV lithography process in order to effectively improve resist sensitivity and roughness. .

（式中、Ｘはハロゲン原子、ヒドロキシ基、及び炭素原子数１乃至６の直鎖状又は分岐鎖状のアルコキシ基からなる群から選ばれる少なくも１つで置換されたフェニル基、ナフチル基又はアントラセニル基を表し、ｖは０又は１を表す。）A first aspect of the present invention is a resist underlayer film forming composition for lithography containing a polymer having an end structure having a structure represented by the following formula (1) and an organic solvent.

(In the formula, X is a phenyl group, a naphthyl group substituted with at least one selected from the group consisting of a halogen atom, a hydroxy group, and a linear or branched alkoxy group having 1 to 6 carbon atoms, or Represents an anthracenyl group, and v represents 0 or 1.)

（式中、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４及びＲ_５は、それぞれ独立に、水素原子、ハロゲン原子、ヒドロキシ基、又は炭素原子数１乃至６の直鎖状若しくは分岐鎖状のアルコキシ基を表す。）X in the formula (1) represents, for example, a group represented by the following formula (2).

(Wherein R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, a halogen atom, a hydroxy group, or a linear or branched alkoxy having 1 to 6 carbon atoms) Represents a group.)

（式中、Ａ_１、Ａ_２、Ａ_３、Ａ_４、Ａ_５及びＡ_６は、それぞれ独立に、水素原子、メチル基又はエチル基を表し、Ｑ_１は二価の有機基を表し、ｍ_１及びｍ_２は０又は１を表す。）The polymer has at least one (for example, one or two) structural units represented by the following formula (3) in the main chain, in addition to having the structure represented by the formula (1) at the terminal. be able to.

(Wherein A ₁ , A ₂ , A ₃ , A ₄ , A ₅ and A ₆ each independently represents a hydrogen atom, a methyl group or an ethyl group, Q ₁ represents a divalent organic group, m ₁ and m ₂ represent 0 or 1)

（式中、Ｑ_２は炭素原子数１乃至１０のアルキレン基、炭素原子数２乃至６のアルケニレン基、炭素原子数３乃至１０の脂環式炭化水素環又は炭素原子数６乃至１４の芳香族炭化水素環を少なくとも１つ有する二価の有機基を表し、前記二価の有機基は、炭素原子数１乃至６のアルキル基、ハロゲン原子、ヒドロキシ基、炭素原子数１乃至６のアルコキシ基、炭素原子数２乃至６のアルコキシカルボニル基、ニトロ基、シアノ基及び炭素原子数１乃至６のアルキルチオ基からなる群から選ばれる少なくとも１つで置換されていてもよく、前記二価の有機基がアルキレン基、アルケニレン基、脂環式炭化水素環又は芳香族炭化水素環を２つ有する場合、該２つのアルキレン基、２つのアルケニレン基、２つの脂環式炭化水素環又は２つの芳香族炭化水素環は、スルホニル基、ジスルフィド基、スルフィド基、カルボニル基，−Ｃ（＝Ｏ）Ｏ−基、−Ｏ−基、−Ｃ（ＣＨ_３）_２−基及び−Ｃ（ＣＦ_３）_２−基からなる群から選ばれる連結基を介して結合していてもよく、ｎ_１及びｎ_２はそれぞれ独立に０又は１を表す。）In the formula (3), Q ₁ is represented by a divalent organic group represented by the following formula (4), for example.

(Wherein Q ₂ is an alkylene group having 1 to 10 carbon atoms, an alkenylene group having 2 to 6 carbon atoms, an alicyclic hydrocarbon ring having 3 to 10 carbon atoms, or an aromatic group having 6 to 14 carbon atoms. Represents a divalent organic group having at least one hydrocarbon ring, and the divalent organic group includes an alkyl group having 1 to 6 carbon atoms, a halogen atom, a hydroxy group, an alkoxy group having 1 to 6 carbon atoms, The divalent organic group may be substituted with at least one selected from the group consisting of an alkoxycarbonyl group having 2 to 6 carbon atoms, a nitro group, a cyano group, and an alkylthio group having 1 to 6 carbon atoms. When having two alkylene groups, alkenylene groups, alicyclic hydrocarbon rings or aromatic hydrocarbon rings, the two alkylene groups, two alkenylene groups, two alicyclic hydrocarbon rings or two aromatic groups The hydrocarbon ring is a sulfonyl group, disulfide group, sulfide group, carbonyl group, —C (═O) O— group, —O— group, —C (CH ₃ ) ₂ — group and —C (CF ₃ ) ₂ —. And may be bonded via a linking group selected from the group consisting of groups, and n ₁ and n ₂ each independently represents 0 or 1.)

（式中、Ｙは下記式（６）又は（７）で表される二価の基を表す。）

（式中、Ｒ_６及びＲ_７はそれぞれ独立に、水素原子、炭素原子数１乃至６のアルキル基、炭素原子数３乃至６のアルケニル基、ベンジル基又はフェニル基を表し、前記フェニル基は、炭素原子数１乃至６のアルキル基、ハロゲン原子、炭素原子数１乃至６のアルコキシ基、ニトロ基、シアノ基及び炭素原子数１乃至６のアルキルチオ基からなる群から選ばれる少なくとも１つで置換されていてもよく、又はＲ_６とＲ_７は互いに結合して、該Ｒ_６及びＲ_７と結合した炭素原子と共に炭素原子数３乃至６の環を形成していてもよい。）In the formula (3), Q ₁ is also represented by a divalent organic group represented by the following formula (5).

(In the formula, Y represents a divalent group represented by the following formula (6) or (7).)

(Wherein R ₆ and R ₇ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group or a phenyl group, Substituted with at least one selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, and an alkylthio group having 1 to 6 carbon atoms. R ₆ and R ₇ may be bonded to each other to form a ring having 3 to 6 carbon atoms together with the carbon atom bonded to R ₆ and R ₇ .

（式中、Ｒ_８は炭素原子数１乃至６のアルキル基、炭素原子数３乃至６のアルケニル基、ベンジル基またはフェニル基を表し、前記フェニル基は、炭素原子数１乃至６のアルキル基、ハロゲン原子、炭素原子数１乃至６のアルコキシ基、ニトロ基、シアノ基及び炭素原子数１乃至６のアルキルチオ基からなる群から選ばれる少なくとも１つで置換されていてもよい。）In the formula (3), Q ₁ is also represented by a divalent organic group represented by the following formula (8).

(Wherein R ₈ represents an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group or a phenyl group, and the phenyl group is an alkyl group having 1 to 6 carbon atoms, (It may be substituted with at least one selected from the group consisting of a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, and an alkylthio group having 1 to 6 carbon atoms.)

Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkoxy group include a methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, sec- Examples include butoxy group and tert-butoxy group. Of these halogen atoms, a fluorine atom and an iodine atom, and among these alkoxy groups, a methoxy group is preferable as a substituent because of its excellent EUV absorption ability. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, and a butylene group. As said alkenylene group, -CH = CH- group is mentioned, for example. As said alkenyl group, an allyl group is mentioned, for example. Examples of the alicyclic hydrocarbon ring include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, and an anthracene ring. When the divalent organic group has two alkylene groups, alkenylene groups, alicyclic hydrocarbon rings or aromatic hydrocarbon rings, the two alkylene groups, two alkenylene groups, two alicyclic hydrocarbon rings Or two aromatic hydrocarbon rings are a sulfonyl group, a disulfide group, a sulfide group, a carbonyl group, a —C (═O) O— group, a —O— group, a —C (CH ₃ ) ₂ — group, a —C ( CF ₃₎ 2 _- may be bonded via a linking group such as.

The resist underlayer film forming composition of the first aspect of the present invention may further contain a crosslinking agent and a crosslinking catalyst.

According to a second aspect of the present invention, a resist underlayer film forming composition according to the first aspect of the present invention is applied on a substrate having a film to be processed and baked to form a resist underlayer film. The substrate coated with the resist is irradiated with extreme ultraviolet light, then developed to form a resist pattern, and the resist pattern is used as a mask to transfer the pattern onto the substrate by the semiconductor element. It is a method of producing.

The resist underlayer film forming composition for lithography of the present invention comprises a polymer capped by having the structure represented by the formula (1) at the end. Applying such a resist underlayer film forming composition to an EUV lithography process is effective in reducing the sensitivity and roughness of the resist.

The resist underlayer film forming composition for lithography of the present invention contains a polymer having a structure represented by the formula (1) at the terminal. The weight average molecular weight of the polymer is, for example, 2000 to 50000.

Examples of the monomer that forms the terminal of the polymer include compounds represented by the following formulas (9-a) to (9-x).

The polymer is obtained, for example, by reacting a polymer having an epoxy group at a terminal with a monomer that reacts with the epoxy group. Examples of such monomers include compounds represented by the above formulas (9-a) to (9-x), that is, 4-fluorobenzoic acid, 4-chlorobenzoic acid, 4-bromobenzoic acid, 4-iodobenzoic acid. Acid, 1-chloro-4-fluorobenzoic acid, 2,4-dichlorobenzoic acid, 2,4,6-trichlorobenzoic acid, 2,3,4,5,6-pentafluorobenzoic acid, 4-chlorosalicylic acid, 3,5-dichlorosalicylic acid, 3,5-dibromosalicylic acid, 3,5-diiodosalicylic acid, tetrachlorobenzoic anhydride, tetrabromobenzoic anhydride, 4-fluorophenol, 2,4,6-tetraiodophenol, 4-hydroxybenzoic acid, 4-methoxybenzoic acid, 4-ethoxybenzoic acid, 4-methoxyphenol, salicylic acid, 3-hydroxy-4-methoxybenzoic acid, Examples include 3,5-dimethoxybenzoic acid and 3,4,5-trimethoxybenzoic acid, but are not limited to these examples. Among these compounds, 4-fluorobenzoic acid, 3,5-diiodosalicylic acid, and 4-methoxybenzoic acid are preferable.

すなわち、１，４−テレフタル酸ジグリシジル、２，６−ナフタレンジカルボン酸ジグリシジル、１，６−ジヒドロキシナフタレンジグリシジル、１，２−シクロヘキサンジカルボン酸ジグリシジル、２，２−ビス（４−ヒドロキシフェニル）プロパンジグリシジル、２，２−ビス（４−ヒドロキシシクロヘキサン）プロパンジグリシジル、１，４−ブタンジオールジグリシジル、モノアリルイソシアヌル酸ジグリシジル、モノメチルイソシアヌル酸ジグリシジル、５，５−ジエチルバルビツール酸ジグリシジル、５，５−ジメチルヒダントインジグリシジルが挙げられるが、これらの例に限定されるわけではない。Examples of the monomer that forms the structural unit represented by the formula (3) and in which m ₁ and m ₂ represent 1 include, for example, epoxy groups represented by the following formulas (10-a) to (10-k). A compound having two,

Namely, diglycidyl 1,4-terephthalate, diglycidyl 2,6-naphthalenedicarboxylate, 1,6-dihydroxynaphthalenediglycidyl, diglycidyl 1,2-cyclohexanedicarboxylate, 2,2-bis (4-hydroxyphenyl) propanedi Glycidyl, 2,2-bis (4-hydroxycyclohexane) propane diglycidyl, 1,4-butanediol diglycidyl, monoallyl isocyanurate diglycidyl, monomethyl isocyanurate diglycidyl, 5,5-diethylbarbiturate diglycidyl, 5,5 -Dimethylhydantoin diglycidyl, but is not limited to these examples.

すなわち、イソフタル酸、５−ヒドロキシイソフタル酸、２，４−ジヒドロキシ安息香酸、２，２−ビス（４−ヒドロキシフェニル）スルホン、コハク酸、フマル酸、酒石酸、３，３’−ジチオジプロピオン酸、１，４−シクロヘキサンジカルボン酸、シクロブタン酸二無水物、シクロペンタン酸二無水物、モノアリルイソシアヌル酸、５，５−ジエチルバルビツール酸、ジグリコール酸、アセトンジカルボン酸、２，２’−チオジグリコール酸、４−ヒドロキシ安息香酸−４−ヒドロキシフェニル、２，２−ビス（４−ヒドロキシフェニル）プロパン、２，２−ビス（４−ヒドロキシフェニル）ヘキサフルオロプロパンが挙げられるが、これらの例に限定されるわけではない。Examples of the monomer that forms the structural unit represented by the formula (3) and in which m ₁ and m ₂ are 0 are represented by the following formulas (11-a) to (11-s), A compound having two carboxyl groups, hydroxyphenyl groups or imide groups, and an acid dianhydride,

That is, isophthalic acid, 5-hydroxyisophthalic acid, 2,4-dihydroxybenzoic acid, 2,2-bis (4-hydroxyphenyl) sulfone, succinic acid, fumaric acid, tartaric acid, 3,3′-dithiodipropionic acid, 1,4-cyclohexanedicarboxylic acid, cyclobutanoic acid dianhydride, cyclopentanoic acid dianhydride, monoallyl isocyanuric acid, 5,5-diethylbarbituric acid, diglycolic acid, acetone dicarboxylic acid, 2,2'-thiodi Examples include glycolic acid, 4-hydroxyphenyl-4-hydroxyphenyl, 2,2-bis (4-hydroxyphenyl) propane, and 2,2-bis (4-hydroxyphenyl) hexafluoropropane. It is not limited.

The number of repeating structural units represented by the formula (3) is, for example, in the range of 10 or more and 10,000 or less.

Examples of the polymer having at least one type of structural unit represented by the formula (3) and having the structure represented by the formula (1) at the terminal include the following formulas (12-a) to (12-d). ), But is not limited to these examples.

The polymer having the structural unit represented by the above formula (12-a) and the terminal includes a compound represented by the formula (9-1), a compound represented by the formula (10-h), a formula (11- The compound represented by j) is used as a raw material and polymerized. The polymer having a structural unit represented by formula (12-d) and a terminal includes a compound represented by formula (9-r), a compound represented by formula (10-h), and a formula (11-j). And the compound represented by the above formula) is used as a raw material and polymerized.

The unit structure represented by a, the unit structure represented by b, and the unit represented by c in formula (12-a), formula (12-b), formula (12-c), and formula (12-d) The molar ratio of the structure satisfies the relationship of a: (b + (c / 2)) = 1: 1.

In the molar ratio a: (b + (c / 2)) = 1: 1 for the formula (12-a), formula (12-b), formula (12-c) and formula (12-d), b and c The molar ratio can be expressed as b: (c / 2) = (1−x): x. However, the molar ratio x is 0.01 to 0.8, preferably 0.1 to 0.3.

Examples of the organic solvent contained in the resist underlayer film forming composition of the present invention include propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether, propylene glycol monopropyl ether, methyl ethyl ketone, Examples thereof include ethyl lactate, cyclohexanone, γ-butyrolactone, N-methylpyrrolidone, and a mixture of two or more selected from these organic solvents. And the ratio of the organic solvent with respect to the resist underlayer film forming composition of this invention is 50 to 99.9 mass%, for example.

The polymer contained in the resist underlayer film forming composition of the present invention is, for example, 0.1% by mass to 50% by mass with respect to the resist underlayer film forming composition.

In addition to the polymer and the organic solvent, the resist underlayer film forming composition of the present invention may contain a crosslinking agent and a crosslinking catalyst that is a compound that promotes a crosslinking reaction. When the component obtained by removing the organic solvent from the resist underlayer film forming composition of the present invention is defined as a solid content, the solid content includes an additive such as a polymer and a crosslinking agent and a crosslinking catalyst added as necessary. The ratio of the additive is, for example, 0.1% by mass to 50% by mass, preferably 1% by mass to 30% by mass with respect to the solid content of the resist underlayer film forming composition of the present invention.

Examples of the crosslinking agent contained as an optional component in the resist underlayer film forming composition of the present invention include hexamethoxymethyl melamine, tetramethoxymethyl benzoguanamine, 1,3,4,6-tetrakis (methoxymethyl) glycoluril (POWDERLINK [ 1174), 1,3,4,6-tetrakis (butoxymethyl) glycoluril, 1,3,4,6-tetrakis (hydroxymethyl) glycoluril, 1,3-bis (hydroxymethyl) urea, 1,1,3,3-tetrakis (butoxymethyl) urea and 1,1,3,3-tetrakis (methoxymethyl) urea. When the cross-linking agent is used, the content of the cross-linking agent is, for example, 1% by mass to 50% by mass, and preferably 5% by mass to 30% by mass with respect to the polymer.

Examples of the crosslinking catalyst contained as an optional component in the resist underlayer film forming composition of the present invention include p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium-p-toluenesulfonate, salicylic acid, camphorsulfonic acid, and 5-sulfosalicylic acid. , Sulfonic acid compounds such as 4-chlorobenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, citric acid, benzoic acid, hydroxybenzoic acid, and carboxylic acid compounds. When the crosslinking catalyst is used, the content of the crosslinking catalyst is, for example, 0.1% by mass to 50% by mass, and preferably 1% by mass to 30% by mass with respect to the crosslinking agent.

The substrate used in the method for manufacturing a semiconductor device according to the second aspect of the present invention is typically a silicon wafer, but is an SOI (Silicon on Insulator) substrate, gallium arsenide (GaAs), indium phosphide ( A compound semiconductor wafer such as InP) or gallium phosphide (GaP) may be used. An insulating film such as a silicon oxide film, a nitrogen-containing silicon oxide film (SiON film), a carbon-containing silicon oxide film (SiOC film), or a fluorine-containing silicon oxide film (SiOF film) is formed on the substrate as a film to be processed. Is formed. In this case, the resist underlayer film is formed on the film to be processed.

In the method for producing a semiconductor device of the present invention, the resist solution used to coat the resist on the resist underlayer film may be either a positive type or a negative type, and a chemically amplified resist sensitive to EUV can be used. . As a developer used for development performed after the EUV irradiation, for example, an alkaline developer such as an aqueous solution of tetramethylammonium hydroxide (TMAH) can be used.

Hereinafter, the present invention will be specifically described with reference to synthesis examples and examples. However, the present invention is not limited to the description of the following synthesis examples and examples.

The weight average molecular weights of the polymers shown in the following Synthesis Examples 1 to 5 in this specification are measurement results by gel permeation chromatography (hereinafter abbreviated as GPC). The measurement conditions etc. are as follows using the Tosoh Co., Ltd. product GPC apparatus for a measurement.
GPC column: Shodex (registered trademark) and Asahipak (registered trademark) (Showa Denko KK)
Column temperature: 40 ° C
Solvent: N, N-dimethylformamide (DMF)
Flow rate: 0.6 ml / min Standard sample: Polystyrene (Tosoh Corporation)

<Synthesis Example 1>
Monomethyldiglycidyl isocyanuric acid (Product name: Me-DGIC, Shikoku Chemicals Co., Ltd.) 12.32 g, 1,2,3,4-cyclobutanetetracarboxylic dianhydride 7.86 g, 3,5-diiodosalicylic acid 5.51 g, benzyltriethylammonium chloride 0.54 g and propylene glycol monomethyl ether 104.89 g were mixed and heated to reflux for 4 hours with stirring. To the resulting polymer solution, 26 g of a cation exchange resin (product name: Dowex [registered trademark] 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite [registered trademark] 15 JWET, Organo Corporation )) 26 g was added, and ion exchange treatment was performed at room temperature for 4 hours. As a result of GPC analysis, the obtained polymer solution had a weight average molecular weight of 3100 in terms of standard polystyrene.

<Synthesis Example 2>
Monoallyl diglycidyl isocyanuric acid (product name: MA-DGIC, Shikoku Chemicals Co., Ltd.) 4.50 g, 1,2,3,4-cyclobutanetetracarboxylic dianhydride 2.71 g, 3,5-diiodo 1.90 g of salicylic acid, 0.19 g of benzyltriethylammonium chloride and 37.18 g of propylene glycol monomethyl ether were mixed and heated to reflux with stirring for 4 hours. To the obtained polymer solution, cation exchange resin (product name: Dowex [registered trademark] 550A, Muromachi Technos Co., Ltd.) 9 g and anion exchange resin (product name: Amberlite [registered trademark] 15 JWET, Organo Corporation )) 9 g was added and ion exchange treatment was performed for 4 hours at room temperature. As a result of GPC analysis, the obtained polymer solution had a weight average molecular weight of 3100 in terms of standard polystyrene.

<Synthesis Example 3>
Monomethyldiglycidyl isocyanuric acid (product name: Me-DGIC, Shikoku Kasei Kogyo Co., Ltd.) 4.93 g, 1,2,3,4-cyclobutanetetracarboxylic dianhydride 3.33 g, 4-fluorobenzoic acid 0. 53 g, benzyltriethylammonium chloride 0.21 g and propylene glycol monomethyl ether 35.99 g were mixed and heated to reflux with stirring for 4 hours. To the resulting polymer solution, 26 g of a cation exchange resin (product name: Dowex (registered trademark) 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite (registered trademark) 10 JWET, Organo Co., Ltd.) )) 10 g was added, and ion exchange treatment was performed at room temperature for 4 hours. As a result of GPC analysis, the obtained polymer solution had a weight average molecular weight of 4500 in terms of standard polystyrene.

<Synthesis Example 4>
Monoallyl diglycidyl isocyanuric acid (product name: MA-DGIC, Shikoku Kasei Kogyo Co., Ltd.) 5.50 g, 1,2,3,4-cyclobutanetetracarboxylic dianhydride 3.31 g, 4-methoxybenzoic acid 0 .91 g, benzyltriethylammonium chloride 0.23 g and propylene glycol monomethyl ether 39.77 g were mixed and heated to reflux for 4 hours with stirring. To the obtained polymer solution, 10 g of a cation exchange resin (product name: Dowex [registered trademark] 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite [registered trademark] 15 JWET, Organo Corporation )) 10 g was added, and ion exchange treatment was performed at room temperature for 4 hours. As a result of GPC analysis, the obtained polymer solution had a weight average molecular weight of 5700 in terms of standard polystyrene.

<Synthesis Example 5>
Monoallyl diglycidyl isocyanuric acid (product name: MA-DGIC, Shikoku Kasei Kogyo Co., Ltd.) 13.00 g, 5,5-diethylbarbituric acid 8.65 g, benzyltriethylammonium chloride 0.53 g and propylene glycol monomethyl ether 88 .72 g was mixed and heated to reflux with stirring for 4 hours. To the obtained polymer solution, cation exchange resin (product name: Dowex [registered trademark] 550A, Muromachi Technos Co., Ltd.) 22 g and anion exchange resin (product name: Amberlite [registered trademark] 15JWET, Organo Corporation )) 22 g was added, and ion exchange treatment was performed at room temperature for 4 hours. As a result of GPC analysis, the obtained polymer solution had a weight average molecular weight of 8,000 in terms of standard polystyrene.

<Example 1>
2.50 g of the polymer solution obtained in Synthesis Example 1 above, tetramethoxymethylglycoluril (product name: POWDERLINK [registered trademark] 1174, manufactured by Nippon Cytec Industries Co., Ltd.), p-toluenesulfonic acid monohydrate A resist underlayer film forming composition was prepared by mixing 0.01 g, propylene glycol monomethyl ether 19.33 g and propylene glycol monomethyl ether acetate 45.11 g.

<Example 2>
2.50 g of the polymer solution obtained in Synthesis Example 2 above, tetramethoxymethylglycoluril (product name: POWDERLINK [registered trademark] 1174, manufactured by Nippon Cytec Industries Co., Ltd.), p-toluenesulfonic acid monohydrate A resist underlayer film forming composition was prepared by mixing 0.01 g, propylene glycol monomethyl ether 18.74 g and propylene glycol monomethyl ether acetate 43.74 g.

<Example 3>
2.50 g of the polymer solution obtained in Synthesis Example 3 above, tetramethoxymethylglycoluril (product name: POWDERLINK [registered trademark] 1174, manufactured by Nippon Cytec Industries Co., Ltd.), paratoluenesulfonic acid monohydrate A resist underlayer film forming composition was prepared by mixing 0.01 g, propylene glycol monomethyl ether 20.57 g and propylene glycol monomethyl ether acetate 48.00 g.

<Example 4>
2.50 g of the polymer solution obtained in Synthesis Example 4 above, tetramethoxymethylglycoluril (product name: POWDERLINK [registered trademark] 1174, manufactured by Nippon Cytec Industries Co., Ltd.), paratoluenesulfonic acid monohydrate A resist underlayer film forming composition was prepared by mixing 0.01 g, propylene glycol monomethyl ether 20.47 g and propylene glycol monomethyl ether acetate 47.76 g.

<Comparative Example 1>
2.50 g of the polymer solution obtained in Synthesis Example 5 above, tetramethoxymethylglycoluril (product name: POWDERLINK [registered trademark] 1174, manufactured by Nippon Cytec Industries Co., Ltd.), 0.11 g, 5-sulfosalicylic acid 0.01 g, A resist underlayer film forming composition was prepared by mixing 35.70 g of propylene glycol monomethyl ether and 16.19 g of propylene glycol monomethyl ether acetate.

(Formation and evaluation of resist pattern)
Each resist underlayer film forming composition prepared in Examples 1 to 4 and Comparative Example 1 of this specification is spin-coated on a silicon wafer so as to have a film thickness of 5 nm and heated at 205 ° C. for 60 seconds. As a result, a resist underlayer film was formed. On the resist underlayer film, a positive resist solution (methacrylate resin solution) for EUV is spin-coated and heated, and an EUV exposure apparatus (manufactured by EXITETECH, EUV Micro Exposure Lithography Tool, MS-13) is used. = 0.35, Quadropole illumination, σ = 0.36 / 0.68. After the exposure, PEB was performed, cooled to room temperature on a cooling plate, developed and rinsed, and a resist pattern was formed. The evaluation was judged from the optimum exposure dose (Eop) when a line and space of 26 nm was formed and the LWR value of the pattern by observation from the upper surface of the pattern.

Evaluation of Eop was performed using a critical dimension scanning electron microscope (CD-SEM), and an exposure amount when a line and space of 26 nm was formed at the time of optimum focus was defined as an Eop value. Note that the smaller the Eop value, the higher the resist sensitivity, because the desired resist pattern can be formed with less exposure energy.

For measurement of LWR, a CD-SEM was used to detect a pattern position two-dimensionally from the top, and the variation in the position was quantified as LWR. Specifically, a line width of a portion of 70% of the height from the bottom of the pattern to the top surface of the resist pattern formed in Eop where the 26 nm line and space is formed using a CD-SEM. The length was measured, and 3σ of those values was taken as the LWR value. Here, σ represents a standard deviation. Note that the smaller the LWR value, the smaller the roughness of the resist to be formed, and the higher the pattern transfer accuracy to the underlying substrate in the manufacturing process.

The measurement results of Eop and LWR of the resist pattern in the line and space of 26 nm are shown in Table 1 below. The Eop and LWR are preferably as small as possible.
[Table 1]

From Table 1, when forming a resist underlayer film using the resist underlayer film forming composition of Examples 1 to 4, compared to forming a resist underlayer film using the resist underlayer film forming composition of Comparative Example 1 Since Eop becomes small, the resist underlayer film forming composition can increase the sensitivity of the resist. Further, when the resist underlayer film is formed using the resist underlayer film forming composition of Example 1 to Example 4, the LWR is higher than when the resist underlayer film is formed using the resist underlayer film forming composition of Comparative Example 1. Therefore, the resist underlayer film forming composition can reduce the roughness of the resist pattern to be formed. That is, it was confirmed that the resist underlayer film forming compositions of Examples 1 to 4 showed useful effects for improving resist sensitivity and roughness in the formation of resist patterns.

Although the embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope described in the above embodiments. Various modifications or improvements can be added to the above embodiment.

Claims (8)

A resist underlayer film forming composition for lithography comprising a polymer having a structure represented by the following formula (1) at the end and an organic solvent.

(In the formula, X is a phenyl group, a naphthyl group substituted with at least one selected from the group consisting of a halogen atom, a hydroxy group, and a linear or branched alkoxy group having 1 to 6 carbon atoms, or Represents an anthracenyl group, and v represents 0 or 1.) The resist underlayer film forming composition for lithography according to claim 1, wherein X in the formula (1) represents a group represented by the following formula (2).

(Wherein R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, a halogen atom, a hydroxy group, or a linear or branched alkoxy having 1 to 6 carbon atoms) Represents a group.) The resist underlayer film forming composition for lithography according to claim 1, wherein the polymer has at least one structural unit represented by the following formula (3) in the main chain.

(Wherein A ₁ , A ₂ , A ₃ , A ₄ , A ₅ and A ₆ each independently represents a hydrogen atom, a methyl group or an ethyl group, Q ₁ represents a divalent organic group, m ₁ and m ₂ each independently represents 0 or 1.) 4. The resist underlayer film forming composition for lithography according to claim 3, wherein in Formula (3), Q ₁ represents a divalent organic group represented by Formula (4) below.

(Wherein Q ₂ is an alkylene group having 1 to 10 carbon atoms, an alkenylene group having 2 to 6 carbon atoms, an alicyclic hydrocarbon ring having 3 to 10 carbon atoms, or an aromatic group having 6 to 14 carbon atoms. Represents a divalent organic group having at least one hydrocarbon ring, and the divalent organic group includes an alkyl group having 1 to 6 carbon atoms, a halogen atom, a hydroxy group, an alkoxy group having 1 to 6 carbon atoms, The divalent organic group may be substituted with at least one selected from the group consisting of an alkoxycarbonyl group having 2 to 6 carbon atoms, a nitro group, a cyano group, and an alkylthio group having 1 to 6 carbon atoms. When having two alkylene groups, alkenylene groups, alicyclic hydrocarbon rings or aromatic hydrocarbon rings, the two alkylene groups, two alkenylene groups, two alicyclic hydrocarbon rings or two aromatic groups The hydrocarbon ring is a sulfonyl group, disulfide group, sulfide group, carbonyl group, —C (═O) O— group, —O— group, —C (CH ₃ ) ₂ — group and —C (CF ₃ ) ₂ —. And may be bonded via a linking group selected from the group consisting of groups, and n ₁ and n ₂ each independently represents 0 or 1.) 4. The resist underlayer film forming composition for lithography according to claim 3, wherein Q ₁ in the formula (3) represents a divalent organic group represented by the following formula (5).

(In the formula, Y represents a divalent group represented by the following formula (6) or formula (7).)

(Wherein R ₆ and R ₇ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group or a phenyl group, Substituted with at least one selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, and an alkylthio group having 1 to 6 carbon atoms. R ₆ and R ₇ may be bonded to each other to form a ring having 3 to 6 carbon atoms together with the carbon atom bonded to R ₆ and R ₇ . In the formula (3), Q ₁ is resist underlayer film forming composition according to claim 3 representing a divalent organic group represented by the following formula (8).

(Wherein R ₈ represents an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group or a phenyl group, and the phenyl group is an alkyl group having 1 to 6 carbon atoms, (It may be substituted with at least one selected from the group consisting of a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, and an alkylthio group having 1 to 6 carbon atoms.) Furthermore, the resist underlayer film forming composition for lithography as described in any one of Claims 1 thru | or 6 containing a crosslinking agent and a crosslinking catalyst. A resist underlayer film forming composition according to any one of claims 1 to 7 is applied on a substrate having a film to be processed and baked to form a resist underlayer film, and a resist underlayer is formed on the resist underlayer film. The substrate coated with the resist is irradiated with extreme ultraviolet light, then developed to form a resist pattern, and the pattern is transferred onto the substrate by dry etching using the resist pattern as a mask to produce a semiconductor element how to.