JP5237743B2 - Composition for forming a resist underlayer film - Google Patents

Description

  The present invention relates to a resist underlayer film forming composition used for forming a resist underlayer film that functions as an antireflection film when a resist pattern is formed on a substrate.

  Conventionally, in the manufacture of a semiconductor device, a lithography process has been used to form a pattern on a substrate. In recent years, along with the high integration of semiconductor elements on circuit boards, pattern formation has been miniaturized. However, as the pattern becomes finer, the influence of standing waves generated in the exposure process increases, and there is a problem that pattern transfer with accurate dimensions becomes difficult. Since a standing wave is generated by interference between incident light and reflected light from the substrate, one method for solving this problem is to provide an antireflection film (resist underlayer film) under the resist film. The resist underlayer film is etched using the resist film as a mask before pattern formation on the substrate.

  The resist underlayer film includes an organic type and an inorganic type. In the case of an organic resist underlayer film, since the resist film is also organic, the etching rate is equivalent. Therefore, when the resist underlayer film is etched, the resist film is similarly etched, and it is difficult to transfer an accurate pattern. On the other hand, it is conceivable that the resist film is thickened to obtain necessary etching resistance. However, with the recent miniaturization of patterns, a pattern formed from a thick resist film has a problem that pattern collapse tends to occur due to an increase in aspect ratio.

In recent years, therefore, an inorganic resist underlayer film has been studied. In the case of an inorganic resist underlayer film, a difference in etching rate with respect to an organic resist film becomes large, and high etching selectivity can be obtained. Therefore, a pattern can be accurately transferred to the resist underlayer film even with a thin resist film. Patent Documents 1 and 2 disclose a silicon material as an example of such an inorganic resist underlayer film.
JP 2004-310019 A Japanese Patent Laying-Open No. 2005-018054

  However, in the resist underlayer films described in Patent Documents 1 and 2, good matching has not been obtained at the interface between the resist film and the resist underlayer film. If the matching between the resist film and the resist underlayer film is poor, the formed resist pattern will be undercut and the pattern will collapse, or it may be difficult to transfer the exact dimensions to the substrate due to the trailing shape. To do.

  This invention is made | formed in view of the said subject, and it aims at providing the composition for resist underlayer film formation which can form the resist underlayer film which has a favorable matching characteristic with a resist film. .

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, it has been found that the above problem can be solved by using a siloxane polymer component having a specific repeating unit, and the present invention as described below has been completed.

  The resist underlayer film forming composition according to the present invention is characterized by containing a siloxane polymer component having a repeating unit represented by the following general formula (1).

（式（１）中、Ｒ^１は、水素原子又は１価の有機基であり、Ｒ^２は、電子吸引性基を有する１価の有機基である。繰返しにおける複数のＲ^１同士又はＲ^２同士は互いに異なっていてもよい。ａは、０又は１である。）

(In the formula (1), R ¹ is a hydrogen atom or a monovalent organic group, R ² is a monovalent organic group having an electron-withdrawing group. Multiple in repeated R ¹ s or R ² And may be different from each other, a is 0 or 1.)

  ADVANTAGE OF THE INVENTION According to this invention, the composition for resist underlayer film formation which can form the resist underlayer film which has a favorable matching characteristic with a resist film can be provided.

≪Composition for resist underlayer film formation≫
<Siloxane polymer component>
(Repeating unit represented by general formula (1))
The resist underlayer film forming composition according to the present invention is characterized by containing a siloxane polymer component having a repeating unit represented by the following general formula (1).

Thus, since the composition for forming a resist underlayer film according to the present invention has a repeating unit containing a monovalent organic group having an electron-attracting group in the siloxane polymer component, the resist underlayer film to be formed is a resist film. Good matching characteristics can be obtained. This is presumably because the resist underlayer film can weaken the influence of capturing the acid (H ⁺ ) generated in the resist film by exposure by having an electron-withdrawing group.

In the general formula (1), R ¹ is a hydrogen atom or a monovalent organic group. A plurality of R ¹ in the repetition may be different from each other.

Although it does not specifically limit as monovalent organic group, C1-C5 linear or branched alkyl group, C1-C5 hydroxyalkyl group, C1-C4 alkoxy group, etc. A sterically small substituent may be mentioned. When R ¹ contains a hydroxyl group, it is preferable that the ratio of the repeating unit in which R ¹ contains a hydroxyl group in the whole repeating unit represented by the general formula (1) is 40 mol% or less. Thereby, gelatinization of the composition for resist underlayer film formation can be prevented. For the same reason, the proportion of the repeating unit having a hydroxyl group is preferably 40 mol% or less with respect to the entire siloxane polymer component.
Examples of the monovalent organic group include crosslinkable organic groups such as an organic group having an epoxy group or an oxetanyl group. When having such a crosslinkable organic group, the curability of the resist underlayer film can be enhanced.

In the general formula (1), R ² is a monovalent organic group having an electron-withdrawing group. A plurality of R ² in the repetition may be different from each other.

Examples of the electron withdrawing group is not particularly limited, -SO 3 R _(wherein, R is a hydrogen atom or an alkyl group or hydroxyalkyl group having 1 to 10 carbon atoms.), A halogen group, and a carbon number 1 And at least one selected from the group consisting of ˜8 halogenated alkyl groups. Among these, a group represented by —SO ₃ R is preferable.

Although it does not specifically limit as a monovalent organic group, A C1-C20 alkyl group is mentioned.
Examples of the monovalent organic group also include organic groups having an aromatic ring such as an alkylaryl group having 6 to 20 carbon atoms and an arylalkyl group having 6 to 20 carbon atoms. Aryl groups include phenyl, naphthyl, anthryl, and phenanthryl groups. When R ² contains an aryl group, it is possible to form a resist underlayer film having an antireflection function and good etching resistance against oxygen-based plasma. In particular, when R ² contains a phenyl group, the light absorption with respect to the wavelength of 193 nm of the ArF laser can be improved. Further, when R ² contains a naphthyl group, an anthryl group, or a phenanthryl group, matching between the formed resist underlayer film and the resist film can be improved.

Among the above, R ² is preferably a monovalent organic group having an aromatic ring to which an electron-withdrawing group is bonded.

  In the general formula (1), a is 0 or 1, but is preferably 0. When a is 0, a ladder skeleton can be formed and the curability of the resist underlayer film can be improved. Furthermore, the Si content ratio of the siloxane polymer component can be maintained high, the inorganicity of the resist underlayer film can be increased, and the etching selectivity with respect to the organic film can be increased.

  The ratio of the repeating unit represented by the general formula (1) is preferably 0.5 to 40 mol%, more preferably 1 to 35 mol%, and more preferably 3 to 30 mol based on the entire siloxane polymer component. More preferably, it is mol%.

(Repeating unit represented by general formula (2))
The siloxane polymer component contained in the resist underlayer film forming composition according to the present invention preferably further has a repeating unit represented by the following general formula (2). In particular, when R ² does not contain an aryl group in the structural unit represented by the general formula (1), it preferably has a repeating unit represented by the general formula (2).

In the general formula (2), R ³ is a hydrogen atom or a monovalent organic group. A plurality of R ³ in the repetition may be different from each other. Examples of R ³ include the same groups as R ¹ in the repeating unit represented by the general formula (1).

  In the general formula (2), Ar is a phenyl group, a naphthyl group, an anthryl group, or a phenanthryl group. A plurality of Ars in the repetition may be different from each other. When the siloxane polymer component has a repeating unit containing a group represented by Ar, a resist underlayer film having an antireflection function and good etching resistance against oxygen-based plasma can be formed. In particular, when Ar is a phenyl group, light absorption with respect to a wavelength of 193 nm of an ArF laser can be improved. Further, when Ar is a naphthyl group, anthryl group, or phenanthryl group, matching between the formed resist underlayer film and the resist film can be improved.

  In the general formula (2), b is 0 or 1, but is preferably 0. When b is 0, a ladder skeleton can be formed and the curability of the resist underlayer film can be improved. Furthermore, the Si content ratio of the siloxane polymer component can be maintained high, the inorganicity of the resist underlayer film can be increased, and the etching selectivity with respect to the organic film can be increased.

  The proportion of the repeating unit represented by the general formula (2) is preferably 5 to 95 mol%, more preferably 20 to 70 mol%, based on the entire siloxane polymer component.

(Repeating unit represented by general formula (3))
The siloxane polymer component contained in the resist underlayer film forming composition according to the present invention may further have a repeating unit represented by the following general formula (3).

In the general formula (3), R ⁴ represents a hydrogen atom, an alkyl group, a hydroxyl group, a monovalent organic group capable of crosslinking, or a hydroxyl group, a polyether group, a carbonyl group, an ester group, a lactone group, an amide group, It is a monovalent organic group having at least one functional group selected from the group consisting of an ether group and a nitrile group. A plurality of R ⁴ in the repetition may be different from each other.

Although it does not specifically limit as an alkyl group, A C1-C5 linear or branched alkyl group is mentioned. When R ⁴ is a hydrogen atom, an alkyl group, or a hydroxyl group, it becomes easy to balance the synthesis between repeating units. Further, when R ⁴ is a monovalent organic group capable of crosslinking, the curability of the resist underlayer film can be improved. Examples of the monovalent organic group capable of crosslinking include an organic group having an epoxy group or an oxetanyl group.

R ⁴ is a monovalent organic group having at least one functional group selected from the group consisting of a hydroxyl group, a polyether group, a carbonyl group, an ester group, a lactone group, an amide group, an ether group, and a nitrile group. In some cases, the perpendicularity of the resist pattern shape can be improved. In particular, when R ⁴ contains a hydroxyl group, the proportion of the repeating unit in which R ⁴ contains a hydroxyl group in the whole repeating unit represented by the general formula (3) is preferably 40 mol% or less. Thereby, gelatinization of the composition for resist underlayer film formation can be prevented.

R ⁴ is preferably a hydrogen atom among the groups described above. This is because the Si content can be kept high. Further, the Si—H bond functions as a crosslinking site, and can improve the curability of the resist underlayer film.

In the general formula (3), ^{R 5} is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. A plurality of R ⁵ in the repetition may be different from each other. Among these, a methyl group is preferable. This is because the Si content can be kept high next to the hydrogen atoms. A polymer composed of Si—H has a property of being easily dissolved in an alkali developer, whereas a polymer composed of Si—Me bonds has a property of being hardly soluble in an alkali developer. For this reason, when the siloxane polymer component has a repeating unit represented by the general formula (3), the resistance to alkali developer of the resist underlayer film when the resist film is alkali-developed can be improved. By having sufficient alkali developer resistance, it is possible to prevent the resist underlayer film from being damaged during development of the resist film, and to make the pattern shape on the substrate obtained after etching good (rectangular).

  In the general formula (3), c is 0 or 1, but is preferably 0. When b is 0, a ladder skeleton can be formed and the curability of the resist underlayer film can be improved. Furthermore, the Si content ratio of the siloxane polymer component can be maintained high, the inorganicity of the resist underlayer film can be increased, and the etching selectivity with respect to the organic film can be increased.

  The ratio of the repeating unit represented by the general formula (3) is 5 to 40 mol% with respect to the entire siloxane polymer component in consideration of the above-mentioned Si content and alkali developer resistance. Is preferable, and it is more preferable that it is 10-30 mol%.

(Repeating unit represented by general formula (4))
The siloxane polymer component contained in the resist underlayer film forming composition according to the present invention may further have a repeating unit represented by the following general formula (4).

In the general formula (4), R ⁶ is a hydrogen atom, an alkyl group, a hydroxyl group, a monovalent organic group capable of crosslinking, or a hydroxyl group, a polyether group, a carbonyl group, an ester group, a lactone group, an amide group, It is a monovalent organic group having at least one functional group selected from the group consisting of an ether group and a nitrile group. A plurality of R ⁴ in the repetition may be different from each other. Examples of R ⁶ include the same groups as R ⁴ in the repeating unit represented by the general formula (3).

In the general formula (4), R ⁷ is a monovalent organic group having at least one functional group selected from the group consisting of an ester group and a polyether group. A plurality of R ⁷ in the repetition may be different from each other. When the siloxane polymer component has a repeating unit containing a group represented by R ⁷ , matching between the formed resist underlayer film and the resist film can be improved.

  Examples of the monovalent organic group having an ester group include groups represented by the following formulas (5) and (6).

  Examples of the monovalent organic group having a polyether group include a group represented by the following general formula (7).

  In the general formula (7), e represents an integer of 2 to 12, f represents an integer of 2 to 6, and g represents an integer of 2 to 200. R ′ represents a hydrogen atom or a monovalent organic group such as an alkyl group.

  In the general formula (4), d is 0 or 1, but is preferably 0. When d is 0, a ladder skeleton can be formed and the curability of the resist underlayer film can be improved. Furthermore, the Si content ratio of the siloxane polymer component can be maintained high, the inorganicity of the resist underlayer film can be increased, and the etching selectivity with respect to the organic film can be increased.

  The ratio of the repeating unit represented by the general formula (4) is preferably 5 to 20 mol% with respect to the entire siloxane polymer component in consideration of the above-described improvement in adhesion, and is 5 to 15 mol%. More preferably.

(Siloxane polymer)
The repeating units represented by the general formulas (1) to (4) may be contained in a single siloxane polymer, or may be contained in different siloxane polymers.
In addition, the mass average molecular weight of the siloxane polymer in the siloxane polymer component is preferably 300 to 400,000. By setting the mass average molecular weight of the siloxane polymer within this range, the film formability and coating property of the resist underlayer film forming composition can be improved. The mass average molecular weight of the siloxane polymer is more preferably 500 to 100,000.

<Solvent>
The composition for forming a resist underlayer film according to the present invention may contain a solvent. The kind of solvent is not specifically limited, A conventionally well-known solvent can be used. Specifically, monohydric alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, alcohols such as ethylene glycol, diethylene glycol, propylene glycol, glycerin, trimethylolpropane, hexanetriol, ethylene glycol monomethyl ether, ethylene Glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopro Alcohol monoethers such as ether, propylene glycol monobutyl ether, esters such as methyl acetate, ethyl acetate, butyl acetate and ethyl lactate (EL), ketones such as acetone, methyl ethyl ketone, cycloalkyl ketone, methyl isoamyl ketone, ethylene Alcohols such as glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether (PGDM), propylene glycol diethyl ether, propylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether All hydroxyl groups of Alcohol ethers obtained by ether reduction, glycol ether esters such as propylene glycol monomethyl ether acetate (PGMEA) and the like.

  The said solvent may be used independently and may be used in combination of 2 or more type. The content of the solvent is preferably 1 to 100 times the mass of the siloxane polymer component. By making content of a solvent into this range, the applicability | paintability of the composition for resist underlayer film formation can be improved. The content of the solvent is more preferably 2 to 20 times the mass of the siloxane polymer component.

<Crosslinking agent>
The composition for forming a resist underlayer film according to the present invention may contain a crosslinking agent. By including a crosslinking agent, the film formability of the resist underlayer film can be further improved. It does not specifically limit as a kind of crosslinking agent, A conventionally well-known crosslinking agent can be used. Specific examples include epoxy compounds such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, and cresol novolak type epoxy resin. Further, divinylbenzene, divinylsulfone, triacryl formal, glyoxal, polyhydric alcohol acrylic ester or methacrylic ester or the like can also be used. Furthermore, compounds having two or more reactive groups in which at least two amino groups of melamine, urea, benzoguanamine, and glycoluril are substituted with a methylol group or a lower alkoxymethyl group can be used.

  Compounds in which at least two amino groups of melamine are substituted with a methylol group or a lower alkoxymethyl group include hexamethylol melamine, hexamethoxymethyl melamine, a compound in which 1 to 6 of hexamethylol melamine are methoxymethylated, and a mixture thereof , Hexamethoxyethyl melamine, hexaacyloxymethyl melamine, compounds in which 1 to 5 methylol groups of hexamethylol melamine are acyloxymethylated, and mixtures thereof.

  Examples of the compound in which at least two of the urea amino groups are substituted with a methylol group or a lower alkoxymethyl group include tetramethylol urea, tetramethoxymethyl urea, tetramethoxyethyl urea, and tetramethylol urea having 1 to 4 methylol groups. Examples thereof include methylated compounds and mixtures thereof.

  Compounds in which at least two amino groups of benzoguanamine are substituted with a methylol group or a lower alkoxymethyl group include compounds in which 1 to 4 methylol groups of tetramethylolguanamine, tetramethoxymethylguanamine, and tetramethylolguanamine are methoxymethylated And mixtures thereof, tetramethoxyethylguanamine, tetraacyloxyguanamine, compounds in which 1 to 4 methylol groups of tetramethylolguanamine are acyloxymethylated, and mixtures thereof.

  Examples of the compound in which at least two of the amino groups of glycoluril are substituted with a methylol group or a lower alkoxymethyl group include tetramethylol glycoluril, tetramethoxyglycoluril, tetramethoxymethylglycoluril, and tetramethylolglycoluril methylol groups 1 to 1. Examples include compounds in which 4 are methylated and mixtures thereof, compounds in which 1 to 4 methylol groups of tetramethylol glycoluril are acyloxymethylated, and mixtures thereof.

  The said crosslinking agent may be used independently and may be used in combination of 2 or more type. As content of a crosslinking agent, 0.1-50 mass parts is preferable with respect to 100 mass parts of siloxane polymer components, and 0.5-40 mass parts is more preferable.

<Acid generator>
The resist underlayer film forming composition according to the present invention may contain an acid generator. It does not specifically limit as a kind of acid generator, A conventionally well-known acid generator can be used. Specifically, onium salts, diazomethane derivatives, glyoxime derivatives, bissulfone derivatives, β-ketosulfone derivatives, disulfone derivatives, nitrobenzyl sulfonate derivatives, sulfonate ester derivatives, sulfonate ester derivatives of N-hydroxyimide compounds, etc. may be used. it can.

  Examples of onium salts include tetramethylammonium trifluoromethanesulfonate, tetramethylammonium nonafluorobutanesulfonate, tetra-n-butylammonium nonafluorobutanesulfonate, tetraphenylammonium nonafluorobutanesulfonate, and tetramethyl p-toluenesulfonate. Ammonium, trifluoromethanesulfonic acid diphenyliodonium, trifluoromethanesulfonic acid (p-tert-butoxyphenyl) phenyliodonium, p-toluenesulfonic acid diphenyliodonium, p-toluenesulfonic acid (p-tert-butoxyphenyl) phenyliodonium, trifluoromethane Triphenylsulfonium sulfonate, trifluoromethanesulfonic acid (p-tert-butoxyphenyl) Phenylsulfonium, trifluoromethanesulfonic acid bis (p-tert-butoxyphenyl) phenylsulfonium, trifluoromethanesulfonic acid tris (p-tert-butoxyphenyl) sulfonium, p-toluenesulfonic acid triphenylsulfonium, p-toluenesulfonic acid (p -Tert-butoxyphenyl) diphenylsulfonium, bis (p-tert-butoxyphenyl) phenylsulfonium p-toluenesulfonate, tris (p-tert-butoxyphenyl) sulfonium p-toluenesulfonate, triphenylsulfonium nonafluorobutanesulfonate , Triphenylsulfonium butanesulfonate, trimethylsulfonium trifluoromethanesulfonate, trimethylsulfone p-toluenesulfonate , Cyclohexylmethyl trifluoromethanesulfonate (2-oxocyclohexyl) sulfonium, cyclohexylmethyl p-toluenesulfonate (2-oxocyclohexyl) sulfonium, dimethylphenylsulfonium trifluoromethanesulfonate, dimethylphenylsulfonium p-toluenesulfonate, trifluoromethane Dicyclohexylphenylsulfonium sulfonate, dicyclohexylphenylsulfonium p-toluenesulfonate, trinaphthylsulfonium trifluoromethanesulfonate, cyclohexylmethyl (2-oxocyclohexyl) sulfonium trifluoromethanesulfonate, (2-norbornyl) methyl trifluoromethanesulfonate (2- Oxocyclohexyl) sulfonium, ethylenebis [Methyl (2-oxocyclopentyl) sulfonium trifluoromethanesulfonate], 1,2'-naphthylcarbonylmethyltetrahydrothiophenium triflate and the like.

  Diazomethane derivatives include bis (benzenesulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (xylenesulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (cyclopentylsulfonyl) diazomethane, bis (n-butylsulfonyl) diazomethane Bis (isobutylsulfonyl) diazomethane, bis (sec-butylsulfonyl) diazomethane, bis (n-propylsulfonyl) diazomethane, bis (isopropylsulfonyl) diazomethane, bis (tert-butylsulfonyl) diazomethane, bis (n-amylsulfonyl) diazomethane Bis (isoamylsulfonyl) diazomethane, bis (sec-amylsulfonyl) diazomethane, bis (tert-amylsulfur) Nyl) diazomethane, 1-cyclohexylsulfonyl-1- (tert-butylsulfonyl) diazomethane, 1-cyclohexylsulfonyl-1- (tert-amylsulfonyl) diazomethane, 1-tert-amylsulfonyl-1- (tert-butylsulfonyl) diazomethane Etc.

  Examples of glyoxime derivatives include bis-o- (p-toluenesulfonyl) -α-dimethylglyoxime, bis-o- (p-toluenesulfonyl) -α-diphenylglyoxime, bis-o- (p-toluenesulfonyl)- α-dicyclohexylglyoxime, bis-o- (p-toluenesulfonyl) -2,3-pentanedione glyoxime, bis-o- (p-toluenesulfonyl) -2-methyl-3,4-pentanedione glyoxime, Bis-o- (n-butanesulfonyl) -α-dimethylglyoxime, bis-o- (n-butanesulfonyl) -α-diphenylglyoxime, bis-o- (n-butanesulfonyl) -α-dicyclohexylglyoxime Bis-o- (n-butanesulfonyl) -2,3-pentanedione glyoxime, bis-o- ( -Butanesulfonyl) -2-methyl-3,4-pentanedione glyoxime, bis-o- (methanesulfonyl) -α-dimethylglyoxime, bis-o- (trifluoromethanesulfonyl) -α-dimethylglyoxime, bis -O- (1,1,1-trifluoroethanesulfonyl) -α-dimethylglyoxime, bis-o- (tert-butanesulfonyl) -α-dimethylglyoxime, bis-o- (perfluorooctanesulfonyl)- α-dimethylglyoxime, bis-o- (cyclohexanesulfonyl) -α-dimethylglyoxime, bis-o- (benzenesulfonyl) -α-dimethylglyoxime, bis-o- (p-fluorobenzenesulfonyl) -α- Dimethylglyoxime, bis-o- (p-tert-butylbenzenesulfonyl) α- dimethylglyoxime, bis-o-(xylene sulfonyl)-.alpha.-dimethylglyoxime, bis-o-(camphorsulfonyl)-.alpha.-dimethylglyoxime, and the like.

  Examples of bissulfone derivatives include bisnaphthylsulfonylmethane, bistrifluoromethylsulfonylmethane, bismethylsulfonylmethane, bisethylsulfonylmethane, bispropylsulfonylmethane, bisisopropylsulfonylmethane, bis-p-toluenesulfonylmethane, and bisbenzenesulfonylmethane. Can be mentioned.

  Examples of the β-ketosulfone derivative include 2-cyclohexylcarbonyl-2- (p-toluenesulfonyl) propane and 2-isopropylcarbonyl-2- (p-toluenesulfonyl) propane.

  Examples of disulfone derivatives include disulfone derivatives such as diphenyl disulfone derivatives and dicyclohexyl disulfone derivatives.

  Examples of the nitrobenzyl sulfonate derivative include nitrobenzyl sulfonate derivatives such as p-toluenesulfonic acid 2,6-dinitrobenzyl and p-toluenesulfonic acid 2,4-dinitrobenzyl.

  Examples of sulfonic acid ester derivatives include 1,2,3-tris (methanesulfonyloxy) benzene, 1,2,3-tris (trifluoromethanesulfonyloxy) benzene, 1,2,3-tris (p-toluenesulfonyloxy). And sulfonic acid ester derivatives such as benzene.

  Examples of sulfonic acid ester derivatives of N-hydroxyimide compounds include N-hydroxysuccinimide methanesulfonic acid ester, N-hydroxysuccinimide trifluoromethanesulfonic acid ester, N-hydroxysuccinimide ethanesulfonic acid ester, N-hydroxysuccinimide 1-propanesulfonic acid. Ester, N-hydroxysuccinimide 2-propanesulfonic acid ester, N-hydroxysuccinimide 1-pentanesulfonic acid ester, N-hydroxysuccinimide 1-octanesulfonic acid ester, N-hydroxysuccinimide p-toluenesulfonic acid ester, N-hydroxysuccinimide p-methoxybenzenesulfonic acid ester, N-hydroxysuccinimide 2-chloroethanesulfonic acid ester N-hydroxysuccinimide benzenesulfonic acid ester, N-hydroxysuccinimide 2,4,6-trimethylbenzenesulfonic acid ester, N-hydroxysuccinimide 1-naphthalenesulfonic acid ester, N-hydroxysuccinimide 2-naphthalenesulfonic acid ester, N-hydroxy 2-Phenylsuccinimide methanesulfonate, N-hydroxymaleimide methanesulfonate, N-hydroxymaleimide ethanesulfonate, N-hydroxy-2-phenylmaleimide methanesulfonate, N-hydroxyglutarimide methanesulfonate N-hydroxyglutarimide benzene sulfonate, N-hydroxyphthalimide methane sulfonate, N-hydroxy Phthalimidobenzenesulfonic acid ester, N-hydroxyphthalimide trifluoromethanesulfonic acid ester, N-hydroxyphthalimide p-toluenesulfonic acid ester, N-hydroxynaphthalimide methanesulfonic acid ester, N-hydroxynaphthalimide benzenesulfonic acid ester, N-hydroxy -5-norbornene-2,3-dicarboximide methanesulfonate, N-hydroxy-5-norbornene-2,3-dicarboximide trifluoromethanesulfonate, N-hydroxy-5-norbornene-2,3- Dicarboximide p-toluenesulfonic acid ester etc. are mentioned.

  The said acid generator may be used independently and may be used in combination of 2 or more type. As content of an acid generator, 0.1-50 mass parts is preferable with respect to 100 mass parts of siloxane polymer components. By setting the content of the acid generator within this range, a resist pattern with good perpendicularity can be formed. As for content of an acid generator, 0.5-40 mass parts is more preferable with respect to 100 mass parts of siloxane polymer components.

<Quaternary ammonium compound>
The resist underlayer film forming composition according to the present invention may contain a quaternary ammonium compound. By containing the quaternary ammonium compound, the resist film formed on the resist underlayer film can be prevented from being reduced, and the shape of the formed resist pattern is also improved. Specifically, the quaternary ammonium compound is preferably a quaternary ammonium compound represented by the following general formula (8).

  In the general formula (8), Ra to Rd are each independently a hydrocarbon group. Examples of the hydrocarbon group include linear, branched, or cyclic saturated or unsaturated hydrocarbon groups. These may have a substituent.

Examples of linear and branched hydrocarbon groups include methyl, methylene, ethyl, ethylene, propyl, propylene, isopropyl, n-butyl, isobutyl, isopropylene and sec-butyl. Group, tertiary butyl group, amyl group, isoamyl group, tertiary amyl group, hexyl group, heptyl group, octyl group, isooctyl group, 2-ethylhexyl group, tertiary octyl group, nonyl group, isononyl group, decyl group, isodecyl Groups and the like.
Examples of the cyclic hydrocarbon group include a cyclic alkyl group and an aryl group. Examples of the cyclic alkyl group include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as cycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one hydrogen atom from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Examples of the aryl group include a phenyl group, a naphthyl group, a methylphenyl group, an ethylphenyl group, a tolyl group, a chlorophenyl group, a bromophenyl group, and a fluorophenyl group.
Moreover, as said substituent, a hydroxyl group, a C1-C3 alkoxy group, etc. are mentioned.

  Among these, those having a total carbon number of Ra to Rd of 10 or more are preferable. By setting the total number of carbon atoms to 10 or more, tailing of the resist pattern formed on the resist underlayer film can be reduced and the resist pattern shape can be improved. Moreover, it is preferable that at least one of Ra to Rd is a hydrocarbon group having 8 or more carbon atoms. Thereby, the tailing of the resist pattern formed on the resist underlayer film can be further reduced. Moreover, the total carbon number of Ra-Rd is preferably 25 or less. Thereby, skirting can be further reduced.

In the general formula (11), X ⁻ is a counter anion. As the counter anion, OH ⁻ , Cl ⁻ , Br ⁻ , F ⁻ , an alkyl carboxylate anion, an aryl carboxylate anion, an aralkyl carboxylate anion and the like are preferable.

  As content of the said quaternary ammonium compound, 0.01-10 mass parts is preferable with respect to 100 mass parts of siloxane polymer components. By setting the content of the quaternary ammonium compound within this range, it is possible to prevent the resist film formed on the resist underlayer film from being reduced, and the shape of the resist pattern to be formed is improved. As for content of a quaternary ammonium compound, 0.1-5 mass parts is more preferable with respect to 100 mass parts of siloxane polymer components, and 0.1-3 mass parts is further more preferable.

<Organic acid>
The composition for forming a resist underlayer film according to the present invention may contain an organic acid. By containing an organic acid, it is possible to prevent the deterioration of the resist underlayer film forming composition over time due to the addition of the quaternary ammonium compound.
Examples of organic acids include organic carboxylic acids, organic phosphonic acids, and organic sulfonic acids. Examples of organic carboxylic acids include aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, lauric acid, palmitic acid and stearic acid; unsaturated aliphatic monocarboxylic acids such as oleic acid and linoleic acid; oxalic acid and malon Aliphatic dicarboxylic acids such as acid, succinic acid, adipic acid and maleic acid; oxycarboxylic acids such as lactic acid, gluconic acid, malic acid, tartaric acid and citric acid; aromatic carboxylic acids such as benzoic acid, mandelic acid, salicylic acid and phthalic acid Examples include acids. Among these, malonic acid is particularly preferable.

  As for content of the said organic acid, 0.01-10 mass parts is preferable with respect to 100 mass parts of siloxane polymer components. By making the content 0.01 parts by mass or more, the temporal stability of the resist underlayer film forming composition can be further improved. Moreover, the inhibition with respect to the said quaternary ammonium compound can be suppressed by making content into 10 mass parts or less.

  The mass ratio of the organic acid to the quaternary ammonium compound is preferably in the range of 100: 20 to 100: 60, and more preferably in the range of 100: 30 to 100: 50. By being within this range, the tailing of the resist pattern formed on the resist underlayer film is reduced, the resist pattern shape is improved, and the temporal stability of the composition for forming the resist underlayer film is further improved. Can do.

<Preparation of composition for forming resist underlayer film>
The composition for forming a resist underlayer film according to the present invention can be obtained by mixing the siloxane polymer component with the above-described solvent, crosslinking agent, acid generator, quaternary ammonium compound, organic acid, and the like as necessary. The obtained resist underlayer film forming composition is preferably filtered with a filter or the like.

≪Resist underlayer film≫
After applying the resist underlayer film forming composition according to the present invention on a workpiece such as a substrate (preferably, on an organic bottom layer formed on the substrate) using a spin coater, a slit nozzle coater or the like. The resist underlayer film can be obtained by heating and drying. For heating, a one-step heating method or a multi-step heating method is adopted. As a multistage heating method, for example, it is preferable to heat at 100 to 120 ° C. for 60 to 120 seconds and then to heat at 200 to 250 ° C. for 60 to 120 seconds. The thickness of the resist underlayer film thus formed is preferably 15 to 200 nm.

  This resist underlayer film is preferably used as an intermediate layer of a multilayer resist process such as a three-layer resist process. An example of a pattern forming method using such a resist underlayer film will be described below with reference to the drawings.

  First, as shown in FIG. 1A, a conventionally known organic bottom layer forming composition is applied onto the substrate 20 by spin coating or the like, and baked at a predetermined temperature to form an organic bottom layer 26. To do. Next, a resist underlayer film forming composition according to the present invention is applied onto the organic bottom layer 26 by a spin coat method or the like, and baked at a predetermined temperature to form a resist underlayer film 22. Next, a conventionally known resist composition is applied by spin coating or the like in the same manner as described above, and pre-baked at a predetermined temperature (preferably at 150 to 300 ° C. for 30 to 300 seconds), and a resist film 24 (preferably , The film thickness is 100 to 300 nm).

  Next, as shown in FIG. 1B, the resist underlayer film 22 is etched using the resist film 24 on which a predetermined pattern is formed by exposure as a mask, and the resist pattern is transferred to the resist underlayer film 22.

  Further, as shown in FIG. 1C, the organic bottom layer 26 is etched using the resist film 24 and the resist underlayer film 22 as a mask, and the resist pattern is transferred to the organic bottom layer 26. In the etching, the resist film 24 may be removed at the same time.

  Finally, as shown in FIG. 1D, etching is performed in the same manner as described above to form a predetermined pattern on the substrate 20.

  Since the organic bottom layer 26 functions as a mask when the substrate 20 is etched, it is desirable that the organic bottom layer 26 has high etching resistance. Further, since it is required not to mix with the upper resist lower layer film 22, it is desirable to crosslink with heat or acid after coating by spin coating or the like. Specifically, it is preferable to use a resin such as cresol novolak, naphthol novolak, catol dicyclopentadiene novolak, amorphous carbon, polyhydroxystyrene, (meth) acrylate, polyimide, polysulfone.

  Moreover, as a resist composition used for formation of the resist film 24, a conventionally well-known thing like the mixture of base resin, an organic solvent, and an acid generator can be used, for example. Base resins include polyhydroxystyrene and derivatives thereof, polyacrylic acid and derivatives thereof, polymethacrylic acid and derivatives thereof, copolymers selected from hydroxystyrene, acrylic acid, methacrylic acid and derivatives thereof, cycloolefin and derivatives thereof. Examples thereof include at least one polymer selected from the group consisting of a derivative, maleimide, acrylic acid and three or more copolymers selected from acrylic acid and derivatives thereof, polynorbornene, and a metathesis ring-opening polymer. The derivatives referred to here are those in which the main skeleton remains after induction so that acrylic acid derivatives include acrylic acid esters, methacrylic acid derivatives include methacrylic acid esters, etc., and hydroxystyrene derivatives include alkoxystyrene. Means what

  Further, as a resist composition for KrF excimer laser, co-polymerization of any one of polyhydroxystyrene, hydroxystyrene, and styrene with any one of acrylic acid ester, methacrylic acid ester, and maleimide N carboxylic acid ester Coalescence is mentioned. Also, as resist compositions for ArF excimer laser, acrylic ester, methacrylic ester, alternating copolymer of norbornene and maleic anhydride, alternating copolymer of tetracyclododecene and maleic anhydride, Examples thereof include polynorbornene and metathesis polymerization by ring-opening polymerization, but are not limited to these polymerization polymers.

  Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.

（ただし、
シロキサンポリマーＡ１［Ｒ＝ｉ−プロピル］・・・（ａ１）：（ａ２）：（ａ３）＝２０：７３：７（モル比）、質量平均分子量：１７０００
シロキサンポリマーＡ２［Ｒ＝ｉ−プロピル］・・・（ａ１）：（ａ２）：（ａ３）＝２２：７５：３（モル比）、質量平均分子量：３３４００
シロキサンポリマーＡ３［Ｒ＝ｉ−プロピル］・・・（ａ１）：（ａ２）：（ａ３）＝１６：７０：１４（モル比）、質量平均分子量：８６００
シロキサンポリマーＡ４［Ｒ＝メチル］・・・（ａ１）：（ａ２）：（ａ３）＝２０：７３：７（モル比）、質量平均分子量：１７０００
シロキサンポリマーＡ５［Ｒ＝ｔｅｒｔ−ブチル］・・・（ａ１）：（ａ２）：（ａ３）＝２０：７３：７（モル比）、質量平均分子量：２３８００） (Siloxane polymers A1 to A5)

(However,
Siloxane polymer A1 [R = i-propyl] (a1) :( a2) :( a3) = 20: 73: 7 (molar ratio), mass average molecular weight: 17000
Siloxane polymer A2 [R = i-propyl] (a1) :( a2) :( a3) = 22: 75: 3 (molar ratio), mass average molecular weight: 33400
Siloxane polymer A3 [R = i-propyl] (a1) :( a2) :( a3) = 16: 70: 14 (molar ratio), mass average molecular weight: 8600
Siloxane polymer A4 [R = methyl] (a1) :( a2) :( a3) = 20: 73: 7 (molar ratio), mass average molecular weight: 17000
Siloxane polymer A5 [R = tert-butyl] (a1) :( a2) :( a3) = 20: 73: 7 (molar ratio), mass average molecular weight: 23800)

（ただし、（ａ１）：（ａ２）：（ａ４）＝２０：７３：７（モル比）、質量平均分子量：２００００） (Siloxane polymer A6)

(However, (a1) :( a2) :( a4) = 20: 73: 7 (molar ratio), mass average molecular weight: 20000)

  These siloxane polymers A1 to A6 were obtained by conventional general production methods. That is, according to the proportion of each structural unit of (a1), (a2), (a3), and (a4), an appropriate amount of monoorganotrichlorosilane or a partial hydrolysis condensate thereof is dissolved in an organic solvent, Was added to hydrolyze to form a partially condensed silicon compound. Furthermore, triorganochlorosilane was added and reacted to terminate the polymerization, and then the solvent was separated by distillation or the like.

[Preparation of resist underlayer film forming composition]
Example 1
Propylene glycol monomethyl ether acetate (PGMEA) as a solvent was added to the siloxane polymer A1 so that the solid content concentration of the siloxane polymer was 2.5% by mass to prepare a resist underlayer film forming composition.

(Examples 2 to 5, Comparative Example 1)
A composition for forming a resist underlayer film was prepared in the same manner as in Example 1 except that the siloxane polymers A2 to A6 were used. Moreover, while calculating Si concentration in solid content in the composition for resist underlayer film formation, k value and n value in 193 nm of the resist underlayer film were measured.

  The Si concentration in the solid content calculated from the resist underlayer film forming compositions of Examples 1 to 5 and Comparative Example 1 is shown in Table 1 below (calculated as the mass ratio of atoms in the siloxane polymer). This value can be regarded as equivalent to the Si concentration in the resist underlayer film to be formed. Table 1 below shows the extinction coefficient (k value) and refractive index (n value) at 193 nm of the resist underlayer film formed using this resist underlayer film forming composition. The k and n values are calculated according to J.H. A. The measurement was performed using “Wbase32” manufactured by WOOLLAM.

[Preparation of composition for forming organic bottom layer]
Copolymer represented by the following formula: 100 parts by mass, glycoluril-based cross-linking agent (product name: Nicalak MX270, manufactured by Sanwa Chemical Co., Ltd.) 20 parts by mass, surfactant (product name: XR104, manufactured by Dainippon Ink and Chemicals, Inc.) ) 0.05 parts by mass and additives (Product name: Catalyst 602, manufactured by Nippon Cytec Co., Ltd.) 1.0 part by mass was mixed, and propylene glycol monomethyl ether acetate (PGMEA) / ethyl lactate (EL) = 3 as a solvent. / 2 (mass ratio) was added so that the solid content concentration was 12% by mass to prepare an organic bottom layer forming composition.

（ただし、（ｄ１）：（ｄ２）＝７５：２５（モル比）、質量平均分子量：６０００）

(However, (d1) :( d2) = 75: 25 (molar ratio), mass average molecular weight: 6000)

[Preparation of resist composition]
The following components are mixed, and propylene glycol monomethyl ether acetate (PGMEA) / ethyl lactate (EL) = 3/2 (mass ratio) is added as a solvent so that the solid content concentration is 6.3% by mass, and the resist composition A product was prepared.

酸発生剤：下記式の化合物・・・１３質量部

酸失活剤：トリ−ｎ−ペンチルアミン・・・０．５４質量部
添加剤：γ−ブチロラクトン・・・１０質量部
サリチル酸・・・１．３２質量部
界面活性剤（製品名：ＸＲ１０４、大日本インキ化学社製）・・・０．１０質量部 Resin: Resin represented by the following formula ((e1) :( e2) :( e3) = 30: 50: 20 (molar ratio), mass average molecular weight: 10,000)... 100 parts by mass

Acid generator: Compound of the following formula: 13 parts by mass

Acid quencher: tri-n-pentylamine 0.54 parts by mass Additive: γ-butyrolactone 10 parts by weight
Salicylic acid: 1.32 parts by mass Surfactant (Product name: XR104, manufactured by Dainippon Ink & Chemicals): 0.10 parts by mass

[Resist pattern formation (1)]
A composition for forming an organic bottom layer was applied onto a silicon wafer using a conventional resist coater, and a heat treatment was performed at 250 ° C. for 90 seconds to form an organic bottom layer having a thickness of 300 nm. Next, on this organic bottom layer, the resist underlayer film forming compositions of Examples 1 to 5 and Comparative Example 1 were applied and subjected to a heat treatment at 250 ° C. for 90 seconds, whereby a resist underlayer having a thickness of 50 nm was obtained. A film was formed. Further, a resist composition is formed on the resist underlayer film to form a resist film, and exposure and development with an ArF excimer laser are performed, whereby a line and space pattern (hereinafter referred to as an L / S pattern) having a line size of 120 nm and a pitch of 240 nm. Formed).

[Resist pattern formation (2)]
In the same manner as the resist pattern formation (1), an L / S pattern having a line size of 50 nm and a pitch of 100 nm was formed.

[Resist pattern evaluation]
The resist pattern shape formed in the resist pattern formation (1) and (2) was evaluated. Evaluation was performed by magnifying and observing the state of the resist pattern using an SEM (scanning electron microscope). In addition, the reference | standard (comparison object) of evaluation was made into the resist pattern (the same dimension) at the time of forming on an organic type bottom layer. That is, if the shape is equal to or greater than the shape of the resist pattern on the organic bottom layer, it can be said that the matching between the inorganic resist underlayer film forming composition and the organic resist composition is good.

  As a result, any of the resist patterns formed on the resist underlayer films of Examples 1 to 5 is a rectangular pattern having high perpendicularity to the resist underlayer film. The shape was not observed, and was a good shape similar to the resist pattern formed on the organic bottom layer. On the other hand, the resist pattern formed on the resist underlayer film of Comparative Example 1 showed tailing, and the rectangularity was inferior to Examples 1-5. From the above, it was confirmed that the composition for forming a resist underlayer film according to the present invention has good matching characteristics with an organic resist film while having an inorganic property with a silicon content of 30% or more.

[Pattern formation and etching evaluation]
The resist pattern (L / S = 90 nm / 90 nm, pattern height 120 nm) obtained in the same manner as in the resist pattern formation (1) was etched as follows to obtain a pattern. As the apparatus, Telius (manufactured by Tokyo Electron) was used. That is, the resist underlayer film is etched (mixed gas of CF ₄ / Ar) using the patterned resist film as a mask, and then the organic bottom layer is etched (O 2 using the resist film and the resist underlayer film as a mask). ₂ / N ₂ mixed gas). At this time, the resist film remaining as a mask was also removed. Subsequently, SiO ₂ was etched using the resist underlayer film and the organic bottom layer as a mask, and the resist underlayer film remaining as a mask was also removed at the same time. Each etching condition is shown in Table 2 below.

  As a result, when any of the resist underlayer film forming compositions of Examples 1 to 5 is used, the L / S resist pattern can be transferred to the substrate, and the resist underlayer films of Examples 1 to 5 can be transferred. It was confirmed that the forming composition had sufficient etching selectivity.

It is a figure for demonstrating pattern formation using the composition for resist lower layer film formation which concerns on this invention.

Explanation of symbols

20 Substrate 22 Resist underlayer film 24 Resist film 26 Organic bottom layer

Claims (5)

A resist underlayer film forming composition comprising a siloxane polymer component having a repeating unit represented by the following general formula (1).

(In the general formula (1), ^{R 1} is a hydrogen atom or a monovalent organic group, ^{R 2} is Ri monovalent organic group der having a group represented by -SO ₃ R, R is hydrogen An atom, an alkyl group having 1 to 10 carbon atoms, or a hydroxyalkyl group, and a plurality of R ¹ or R ² in the repetition may be different from each other, and a is 0 or 1.   2. The resist underlayer film forming composition according to claim 1, wherein the ratio of the repeating unit represented by the general formula (1) in the siloxane polymer component is 0.5 to 40 mol%. Wherein R ^2, the -SO 3 resist underlayer film forming composition of claim 1 or 2, wherein the group represented by _R is a monovalent organic group having an aromatic ring bonded. The composition for forming a resist underlayer film according to any one of claims 1 to 3, wherein the siloxane polymer component further has a repeating unit represented by the following general formula (2).

(In the general formula (2), R ³ is a hydrogen atom or a monovalent organic group, Ar is a phenyl group, a naphthyl group, an anthryl group, or a phenanthryl group. Multiple in repeated R ³ s or Ar And may be different from each other, b is 0 or 1.) The composition for forming a resist underlayer film according to any one of claims 1 to 4 , wherein the siloxane polymer component further has a repeating unit represented by the following general formula (3).

(In general formula (3), R ⁴ represents a hydrogen atom, an alkyl group, a hydroxyl group, a monovalent organic group capable of crosslinking, or a hydroxyl group, a polyether group, a carbonyl group, an ester group, a lactone group, an amide group. , An ether group, and a monovalent organic group having at least one functional group selected from the group consisting of nitrile groups, and R ⁵ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. R ^{4 s} or R ^{5 s} may be different from each other, and c is 0 or 1.)

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