TWI666265B - Polysiloxane composition for forming photoresist underlayer film and pattern formation method - Google Patents

Abstract

An object of the present invention is to provide a polysiloxane composition for forming a photoresist underlayer film capable of suppressing defects in the photoresist layer under a multilayer photoresist process, and a composition using the same Method for forming pattern of objects.

The present invention is a polysiloxane composition for forming a photoresist underlayer film containing a polysiloxane and an acid generator, characterized in that the acid generator includes an onium cation and an acid anion, the onium cation includes an alicyclic structure, and an aliphatic A heterocyclic structure, an aromatic ring structure having a chain substituent, or a combination thereof. The onium cation preferably includes an alicyclic structure, an aliphatic heterocyclic structure, or a combination thereof. The sum of the atomic weights of the atoms constituting the acid anion is preferably 350 or less.

Description

Polysiloxane composition for forming photoresist underlayer film and pattern formation method

The present invention relates to a polysiloxane composition for forming a photoresist underlayer film and a pattern forming method using the same.

In recent years, with the miniaturization of semiconductor devices and the like, it is required to form finer photoresist patterns. For this requirement, various multilayer photoresist processes using photoresist underlayer films have been developed. Such a multilayer photoresist process is exemplified as follows. First, a photoresist underlayer film is formed on a substrate to be processed by using a composition for forming a photoresist underlayer film containing silicon atoms. Next, a photoresist composition is formed on the photoresist underlayer film. The photoresist film is an organic film having a different etching selection ratio from the above photoresist underlayer film. Subsequently, the photoresist film is exposed to develop with a developing solution to obtain a photoresist pattern. Then, the photoresist pattern is transferred onto the photoresist underlayer film and the substrate to be processed by dry etching to obtain a substrate provided with a desired pattern.

In the photoresist underlayer film forming composition, an acid generator is added in order to make a photoresist pattern formed on the photoresist underlayer film good (see Japanese Patent Application Laid-Open No. 2007-164148 and Japanese Patent Application Laid-Open No. 2010- 122297). However, these compositions for forming a photoresist underlayer film have defects in the photoresist underlayer film due to an acid generator, and they have the disadvantage that it is difficult to form a fine photoresist pattern.

[Prior technical literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2007-164148

[Patent Document 2] Japanese Patent Laid-Open No. 2010-122297

The present invention has been completed based on the above-mentioned problems, and an object thereof is to provide a polysiloxane composition for forming a photoresist underlayer film that can suppress defects in the photoresist underlayer film in a multilayer photoresist process and use the same Pattern formation method of polysiloxane composition for resist film formation.

In order to solve the above problems, the present invention is a polysiloxane composition for forming a photoresist underlayer film containing a polysiloxane and an acid generator, wherein the acid generator includes an onium cation and an acid anion, and the onium cation includes An alicyclic structure, an aliphatic heterocyclic structure, an aromatic ring structure having a chain substituent, or a combination thereof.

In addition, another invention for solving the above-mentioned problems is A pattern forming method includes the steps of: forming a photoresistive underlayer film on one side of a substrate; forming a photoresistive pattern on an opposite side of the photoresistive underlayer film from the substrate; and The photoresist pattern is used as a photomask to sequentially dry-etch the photoresist underlayer film and the substrate in sequence; and the photoresist underlayer film is formed by using the polysiloxane composition for photoresist underlayer film formation.

Here, the "acid anion" means an anion which becomes an acid by the addition of a proton.

According to the polysiloxane composition and pattern formation method for forming a photoresist underlayer film according to the present invention, defects in the photoresist underlayer film can be suppressed during a multilayer photoresist process. According to this, these patterns can be used for semiconductor device manufacturing and the like which are expected to be further refined in the future.

<Polysiloxane composition for forming photoresist underlayer film>

The composition for forming a photoresist underlayer film contains a polysiloxane and an acid generator. This acid generator includes an onium cation and an acid anion, and the onium cation includes an alicyclic structure, an aliphatic heterocyclic structure, an aromatic ring structure having a chain substituent, or a combination thereof. Thereby, defects caused by the acid generator in the photoresist underlayer film formed by the photoresist underlayer film-forming polysiloxane composition are reduced. The polysiloxane composition for forming a photoresist underlayer film has The reason why the above-mentioned structure exerts the above-mentioned effect is not clear, but it is presumed as follows, for example. That is, by providing the onium cation with a bulky structure, the cohesiveness of the acid generator itself is reduced, and the dispersibility of the acid generator in the photoresist underlayer film is improved. As a result, it is thought that it is possible to reduce defects such as local change in etching rate due to agglomeration of the acid generator, or local gelation caused by denaturation of the polysiloxane with the acid generator generated, and to suppress the photoresist lower layer. The occurrence of defects in the film. In addition, these results make the shape of the photoresist pattern formed on the photoresist underlayer film favorable.

The polysiloxane composition for forming a photoresist underlayer film may contain other components such as a solvent and a nitrogen-containing compound as long as the aforementioned effects are not impaired. Each component is explained below.

[Polysiloxane]

The polysiloxane is not particularly limited as long as it is a polymer having a siloxane bond, but it is preferably a hydrolyzed condensate of a silane compound represented by the following formula (i). The silane compounds used in the synthesis of polysiloxane may be used alone or in combination of two or more.

Here, the "hydrolyzed condensate" means a hydrolyzed condensate obtained by condensing a part of silanol groups in a hydrolyzed silane compound.

[Chem. 1] R ^A _a SiX _4-a (i)

In the formula (i), R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. X is a halogen atom or -OR ^B. R ^B is a monovalent organic group having 1 to 20 carbon atoms. a is an integer from 0 to 3. When R ^A is plural, the plural R ^A may be the same or different. When X is plural, plural X may be the same or different.

The "organic group" herein refers to a group containing at least one carbon atom.

The monovalent organic group having 1 to 20 carbon atoms represented by the above-mentioned R ^A or R ^B is a monovalent hydrocarbon group, a group containing a hetero atom-containing group between carbon and carbon of the hydrocarbon group, and a part or all of hydrogen atoms of these groups Substituted by a substituent and the like.

Examples of the monovalent hydrocarbon group include a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group.

Examples of the chain hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, and butyl; alkenyl groups such as vinyl, propenyl, and butenyl; alkynyl groups such as ethynyl, propynyl, and butynyl; .

Examples of the alicyclic hydrocarbon group include cycloalkyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, norbornyl, and adamantyl; cyclopropenyl, cyclopentenyl, cyclohexenyl, and norbornenyl Isocycloalkenyl and the like.

Examples of the aromatic hydrocarbon group include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthracenyl; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl.

The heteroatom-containing group refers to a group having a divalent or higher heteroatom in the structure. The heteroatom-containing group may have one heteroatom or may have There are more than two.

The heteroatom having a divalent or higher valence of the heteroatom-containing group is not particularly limited as long as it is a heteroatom having a divalent or higher valence, and examples thereof include an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, and boron. Atom, etc.

The above heteroatom-containing groups are listed as, for example: -SO-, -SO _2- , -SO ₂ O-, -SO ₃ -and the like formed only by heteroatoms; -CO-, -COO-, -COS-, -CONH-, -OCOO-, -OCOS-, -OCONH-, -SCONH-, -SCSNH-, -SCSS-, etc. are combined carbon and heteroatom groups.

Examples of the substituent include a halogen atom, a hydroxyl group, a carboxyl group, a nitro group, and a cyano group.

The a is preferably an integer of 0 to 2, more preferably 1 and 2.

Examples of the silane compound represented by the above formula (i) are, for example, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, methyl ginseng (dimethylamine Alkyltrialkoxysilanes such as silane; vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, etc. Trialkoxysilanes; aryltrialkoxysilanes such as phenyltrimethoxysilane; 4-methylphenyltrimethoxysilane and more than one hydrogen atom on the aromatic ring via alkyl, hydroxyl , Alkoxy, amine or alkylcarbonyloxy Aryltrialkoxysilanes; Aralkyltrialkoxysilanes; Tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-butoxy Tetraalkoxysilanes such as silane, tetra-second butoxysilane, and tetra-third-butoxysilane; tetraarylsilanes such as tetraphenoxysilane; oxetanyltrimethoxysilane, ethylene oxide Epoxy-containing silanes such as trimethoxysilane, epoxyethylmethyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane; 3- (trimethoxysilyl) propyl amber Acid anhydrides, 2- (trimethoxysilyl) ethylsuccinic anhydride, 3- (trimethoxysilyl) propylmaleic anhydride, 2- (trimethoxysilyl) ethylglutaric anhydride, etc. Silanes; Tetrahalosilanes, etc.

Among these, from the viewpoint of excellent dry etching resistance of the obtained photoresist underlayer film, tetramethoxysilane and tetraethoxysilane are preferred.

In addition, from the viewpoint of the reactivity of the silane compound and the ease of handling of the substance, phenyltrimethoxysilane, 4-methylphenyltrimethoxysilane, methyltrimethoxysilane, and methyltriethoxysilane are used. , Vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, and allyltriethoxysilane are preferred.

Furthermore, from the viewpoint of suppressing pattern collapse of the photoresist pattern, oxetanyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3- (trimethoxysilyl) propane Preferred are succinic anhydride and 4-hydroxyphenyltrimethoxysilane.

In the synthesis of the polysiloxane, a silane compound other than the silane compound represented by the formula (i) may be used. Examples of the silane compound include hexamethoxydisilanes, hexaethoxydisilanes, hexaphenoxydisilanes, 1,1,1,2,2-pentamethoxy-2-methyldisilanes, 1, 1,1,2,2-pentaethoxy-2-methyldisilanes, 1,1,2,2-tetramethoxy-1,2-dimethyldisilanes, 1,1,2,2 -Tetraethoxy-1,2-dimethyldisilanes, 1,1,2,2-tetraphenoxy-1,2-dimethyldisilanes, 1,1,2-trimethoxy-1 , 2,2-trimethyldisilazane, 1,1,2-triethoxy-1,2,2-trimethyldisilazane, 1,1,2-triphenoxy-1,2,2 -Trimethyldisilazane, 1,2-dimethoxy-1,1,2,2-tetramethyldisilazane, 1,2-diethoxy-1,1,2,2-tetramethyl Disilanes, 1,2-diphenoxy-1,1,2,2-tetramethyldisilanes, bis (trimethoxysilyl) methane, bis (triethoxysilyl) methane, 1,2 -Bis (trimethoxysilyl) ethane, 1,2-bis (triethoxysilyl) ethane, 1- (dimethoxymethylsilyl) -1- (trimethoxysilyl) Methane, 1- (diethoxymethylsilyl) -1- (triethoxysilyl) methane, bis (dimethoxymethylsilyl) methane, bis (diethoxymethylsilyl) ) Methane, 1,2-bis (dimethoxymethylsilane) ) Ethane, 1,2-bis (diethoxymethylsilyl) ethane, 1- (dimethoxymethylsilyl) -1- (trimethylsilyl) methane, 1- (di Disilanes such as ethoxymethylsilyl) -1- (trimethylsilyl) methane, bis (trimethoxysilyl) benzene, bis (triethoxysilyl) benzene; polydimethoxy Methyl carbosilane, polydiethoxy methyl carbosilane, etc. Polycarbosilanes and so on.

The lower limit of the content of the polysiloxane in the polysiloxane composition for forming a photoresist underlayer film is preferably 80% by mass relative to the total solid content in the polysiloxane composition for forming a photoresist layer under film. It is preferably 90% by mass, and more preferably 95% by mass. The polysiloxane composition for forming a photoresist underlayer film may contain only one kind of polysiloxane, or may contain two or more kinds. The "solid content" herein means, for example, the ratio of the residual content of the solution fired at 250 ° C for 30 minutes to the solution before firing.

The lower limit of the weight-average molecular weight (Mw) of polysiloxane in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 500, more preferably 800, more preferably 1,000, and most preferably 1,200. . On the other hand, the upper limit of the Mw is preferably 20,000, more preferably 15,000, still more preferably 10,000, and most preferably 5,000.

In addition, Mw in this specification is an analysis using GPC column (2 G2000HXL, 1 G3000HXL, 1 G4000HXL) manufactured by TOSOH company, flow rate: 1.0 ml / min, dissolution solvent: tetrahydrofuran, column temperature: 40 ° C. Conditions are based on monodisperse polystyrene as a standard, and values measured by a gel permeation chromatography (GPC).

As a method for hydrolyzing and condensing the silane compound represented by the above formula (i) and other silane compounds optionally used, a conventional method of hydrolysis and condensation can be used.

[Acid generator]

The acid generator includes an onium cation and an acid anion. Above Onium The proton includes at least one of an alicyclic structure, an aliphatic heterocyclic structure, and an aromatic ring structure having a chain substituent. The acid generator generates an acid by exposure or heating. This acid causes a cross-linking reaction between molecular chains such as polysiloxane. Thereby, the shape of the photoresist pattern formed on the photoresist underlayer film is improved. In addition, since the onium cation of the acid generator has the specific structure described above, it is considered to be a better dispersion state in the photoresist underlayer film as described above. As a result, defects in the photoresist underlayer film due to the acid generator are suppressed. It happened.

Examples of the alicyclic structure include a monocyclic naphthenic structure such as a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, and a cyclohexane structure; a polycyclic naphthenic structure such as a norbornane structure and an adamantane structure.

Examples of the aliphatic heterocyclic structure include monocyclic structures such as an ethylene oxide structure, an oxetane structure, an oxetane structure, a thietane structure, and a thiane structure; Polycyclic structures such as oxa norbornane structure, azanorbornene structure, thionorbornene structure, norbornane lactone structure, oxa norbornane lactone structure, norbornane sultone structure, etc.

Examples of the aromatic ring structure having a chain substituent include those in which a part or all of hydrogen atoms in the aromatic ring structure are substituted with a chain hydrocarbon.

Examples of the aromatic ring structure include a benzene structure, a naphthalene structure, an anthracene structure, and a phenanthrene structure.

Examples of the chain hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, and butyl; Alkenyl groups such as vinyl, propenyl, and butenyl; alkynyl groups such as ethynyl, propynyl, butynyl, and the like.

The onium cation is preferably a cation represented by the following formulae (1-1) and (1-2).

In the formula (1-1), R ^1a , R ^1b and R ^{1c are} each independently a monovalent organic group having 1 to 20 carbon atoms. However, at least one of R ^1a , R ^1b and R ^1c has an alicyclic structure. m1, m2, and m3 are each independently an integer of 0 to 3. However, not all m1, m2, and m3 are zero. n1, n2, and n3 are each independently an integer of 0 ~ 2. When m1 is 2 or more, a plurality of R ^1a may be the same or different. When m2 is 2 or more, a plurality of R ^1b may be the same or different. When m3 is 2 or more, a plurality of R ^1c may be the same or different.

In the formula (1-2), R ² is a monovalent organic group having 1 to 20 carbon atoms. p, q, and r are each independently an integer of 0 to 2. When p is 2 or more, a plurality of R ² may be the same or different.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by the aforementioned R ^1a , R ^1b and R ^1c are the same as those exemplified by the above-mentioned R ^A or R ^B. Among these, R ^1a , R ^1b and R ^1c are preferably an alicyclic hydrocarbon group, more preferably a cycloalkyl group, and still more preferably a cyclohexyl group.

The above m1, m2 and m3 are preferably 0 and 1. In addition, it is preferable that only one of m1, m2, and m3 is 1, and the other two are 0. The aforementioned n1, n2, and n3 are preferably 0 and 1, and more preferably 0.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by the aforementioned R ² include the same groups as those exemplified by the above-mentioned R ^A or R ^B. Among these, R ² is preferably a chain hydrocarbon group having a hetero atom, more preferably an alkyl group having an oxygen atom, and still more preferably a butyl group having an oxygen atom.

The above-mentioned p, q and r are preferably 0 and 1, more preferably 1.

Examples of the acid anion include an oxyacid anion, a sulfofluorenimidine anion, and the like. Examples of the oxyacid anion include a sulfonate anion, a carboxylate anion, and a phosphonate anion. Among these, from the viewpoint of the strength of the acid generated, a sulfonate anion is preferred.

The sulfonate anion is preferably an anion represented by the following formula (2-a).

[Chemical Formula 3] _{^{R 3 -SO 3 - (2-}} a)

In the formula (2-a), R ³ is a monovalent organic group having 1 to 20 carbon atoms.

The monovalent organic group having 1 to 20 carbon atoms represented by the aforementioned R ³ is exemplified by the same groups as those exemplified by the aforementioned R ^A or R ^B. R ^{3 is} preferably a hydrocarbon group having a halogen atom, more preferably a hydrocarbon group having a fluorine atom, more preferably a hydrocarbon group having 1 to 6 carbon atoms having a fluorine atom, and most preferably 4 to 4 carbon atoms having a fluorine atom. Hydrocarbon group of 6;

The sulfofluorenimidine anion is preferably an anion represented by the following formula (2-b).

In the formula (2-b), L is an alkylene group having 2 to 6 carbon atoms (hereinafter, also referred to as "fluorinated alkylene group") in which at least one hydrogen atom is replaced by a fluorine atom.

The carbon number of the fluorinated alkylene group is preferably 3, 4, and 5, and more preferably 3. By setting the carbon number to the above-mentioned value, it is possible to reduce the elution of water from the polysiloxane composition for forming a photoresist underlayer film.

In addition, the lower limit of the fluorination ratio, which is the proportion of the hydrogen atoms in the fluorinated alkylene group substituted with fluorine atoms, is preferably 70%, more preferably 90%. On the other hand, the upper limit of the fluorination ratio is preferably 100%. By making the fluorination ratio into the above range, the intensity of the acid generated by the acid generator is appropriately adjusted.

The fluorinated alkylene group is preferably a perfluoroalkylene group in which all hydrogen atoms of the alkylene group are replaced with fluorine atoms.

Examples of the fluorinated alkylene group include tetrafluoroethylene, 1,2-hexafluoropropyl, 1,3-hexafluoropropyl, 1,2-octafluorobutyl, and 1,3-octafluoro Fluorobutyl, 1,4-octafluorobutyl, 2-trifluoromethyl-1,3-pentafluoropropyl, 1,5-perfluoropentyl, 1,6-perfluorohexyl, 1,7-perfluoroheptyl, 1,8-perfluorooctyl, etc.

The anion represented by the formula (2-b) is preferably represented by the following formulae (2-b-1) to (2-b-3).

The atomic weight and lower limit of the atoms constituting the acid anion are preferably 150, more preferably 180, and even more preferably 190. On the other hand, the upper limit of the atomic weight sum is preferably 350, more preferably 320, and even more preferably 300. When the atomic weight and the lower limit are not reached, the diffusion length of the acid generated from the acid generator may be too large, and the shape of the photoresist pattern may be deteriorated. On the contrary, when the sum of the atomic weights exceeds the upper limit, the dispersibility of the acid generator in the film formed from the polysiloxane composition for forming a photoresist underlayer film may decrease.

Examples of the acid generator include compounds (3-1) to (3-8) represented by the following formulae (3-1) to (3-8). Among these, the compound (3-1), the compound (3-2), the compound (3-7), and the compound (3-8) are preferable.

The lower limit of the content of the acid generator relative to 100 parts by mass of the polysiloxane is preferably 3 parts by mass, more preferably 5 parts by mass. On the other hand, the upper limit of the content is preferably 20 parts by mass, and more preferably 10 parts by mass. The acid generator may be used alone or in combination of two or more.

[Other ingredients]

Other components that may be contained in the photoresist underlayer film-forming polysiloxane composition are, for example, solvents, nitrogen-containing compounds, β-diketones, colloidal silica, colloidal alumina, organic polymers, and surfactants. , Alkali generator and so on.

(Solvent)

The solvent can be used without particular limitation as long as it can dissolve or disperse the polysiloxane and other optional components. Examples of the solvent include organic solvents such as alcohol-based solvents, ether-based solvents, ketone-based solvents, amidine-based solvents, ester-based solvents, and hydrocarbon-based solvents.

Examples of the alcohol-based solvent include: aliphatic monoalcohol solvents having 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol; cycloaliphatic monoalcohol solvents having 3 to 18 carbon atoms such as cyclohexanol. Solvents; polyhydric alcohol solvents with 3 to 18 carbons such as 1,2-propanediol; polyether alcohol solvents with 3 to 19 carbons such as propylene glycol monoethyl ether.

The above ether-based solvents are listed as, for example: Dilipid anti-ether ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; aromatic ring ether solvents such as anisole and diphenyl ether; cyclic ether solvents such as tetrahydrofuran and dioxane Wait.

Examples of the ketone-based solvent include acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, and ethyl acetate. Chain ketone solvents such as methyl n-butyl ketone, methyl n-hexyl ketone, diisobutyl ketone, trimethyl nonanone, and acetophenone; cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, Cyclic ketone solvents such as methylcyclohexanone; diketone solvents such as 2,4-pentanedione and acetoacetone.

Examples of the amidoamine-based solvents include N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, and N-methylacetamide. , N, N-dimethylacetamide, N-methylpropylamine, and other chain-like amine solvents; N-methylpyrrolidone, N, N'-dimethylimidazolidone and other rings Amidamine-based solvents and the like.

Examples of the ester-based solvent include monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; lactone-based solvents such as γ-butyrolactone and valerolactone; and polyols such as propylene glycol monomethyl ether acetate Partial ether carboxylic acid ester solvents; polycarboxylic acid diester solvents such as diethyl oxalate; Carbonate solvents such as dimethyl carbonate and diethyl carbonate.

Examples of the hydrocarbon-based solvent include n-pentane, isopentane, n-hexane, isohexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, isooctane, Aliphatic hydrocarbon solvents such as cyclohexane and methylcyclohexane; benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, isopropyl Aromatic hydrocarbon solvents such as diphenylbenzene, diethylbenzene, isobutylbenzene, triethylbenzene, diisopropylbenzene, n-pentylnaphthalene; dichloromethane, chloroform, fluorocarbon, chlorobenzene, dichlorobenzene And other halogen-containing solvents.

As the solvent, among these, an alcohol-based solvent and an ester-based solvent are preferred, a polyol partial ether-based solvent and a polyol monoalkyl ether acetate-based solvent are more preferable, and propylene glycol monoethyl ether and Propylene glycol monomethyl ether acetate. The solvents may be used alone or in combination of two or more.

(water)

The polysiloxane composition for forming a photoresist underlayer film may contain water. When water is contained, polysiloxane is hydrated, which improves storage stability. In addition, when it contains water, it can promote the hardening of the photoresist underlayer film to form a dense film.

When the polysiloxane composition for forming a photoresist underlayer film contains water, the lower limit of the water content rate is preferably 0.1% by mass, more preferably 0.2% by mass. On the other hand, the upper limit of the content ratio is preferably 30% by mass, more preferably 20% by mass, and even more preferably 15% by mass. Water content exceeds the upper limit In some cases, the storage stability of the polysiloxane composition for forming a photoresist underlayer film may decrease, and the uniformity of the coating film may decrease.

(Nitrogen compounds)

The nitrogen-containing compound is a compound having a basic amine group or a compound having a group that becomes a basic amine group by the action of an acid. The nitrogen-containing compound has an effect of improving characteristics such as ashing resistance of the photoresist underlayer film obtained from the photoresist underlayer film-forming polysiloxane composition. This effect is considered to be caused by the presence of a nitrogen-containing compound in the photoresist underlayer film, thereby promoting the crosslinking reaction in the photoresist underlayer film.

Examples of the nitrogen-containing compound include an amine compound, a sulfonylamine-containing compound, a urea compound, and a nitrogen-containing heterocyclic compound.

The above amine compounds are exemplified by mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines or derivatives thereof; ethylenediamine, N, N, N ', N'-tetramethylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diamine Diphenyl ether, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylamine, 2,2-bis (4-aminophenyl) propane, 2- (3 -Aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4-aminophenyl) ) -2- (4-hydroxyphenyl) propane, 1,4-bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4- Aminophenyl) -1-methylethyl) benzene, bis (2-dimethylaminoethyl) ether, bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxaline alcohol, N, N, N ', N'-((2-hydroxypropyl) ethylenediamine, N, N, N ', N ", N" -penta Methyldiethylenetriamine and the like.

Examples of the amidino group-containing compound include, for example, an amine compound containing an N-third butoxycarbonyl group, an amine compound containing an N-third pentoxyoxy group, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propylamine, benzamidine, pyrrolidone, N-methylpyrrolidone , N-ethylamido-1-adamantylamine, isocyanurate (2-hydroxyethyl) ester, and the like.

Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, and 1,3-diphenyl. Urea, tri-n-butylthiourea, etc.

Examples of the nitrogen-containing heterocyclic compound include imidazoles; pyridines; piperazines; pyrazines; pyrazoles, pyridines, quinazolines, purines, pyrrolidines, piperidines, piperidine ethanol, 3-piperidine-1 , 2-propanediol, morpholine, 4-methylmorpholine, 1- (4-morpholinyl) ethanol, 4-ethylamidomorpholine, 3- (N-morpholinyl) -1,2-propanediol, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] octane, etc.

As the nitrogen-containing heterocyclic compound, a sulfonylamine-containing compound is preferred among these, more preferably an amine-containing compound containing N-third butoxycarbonyl group and an amine-containing group containing N-third pentoxycarbonyl group. Compound.

The upper limit of the content of the nitrogen-containing compound is based on the viewpoint of making the pattern shape good, and is preferably 30 parts by mass, more preferably 10 parts by mass, with respect to 100 parts by mass of the polysiloxane composition for forming a photoresist underlayer film. It is more preferably 1 part by mass. One or two nitrogen-containing compounds can be used.

<Method for preparing polysiloxane composition for forming photoresist underlayer film>

The polysiloxane composition for forming a photoresist underlayer film is obtained by, for example, mixing a polysiloxane, an acid generator, and any other components, and dissolving or dispersing it in a solvent. The lower limit of the solid content concentration of the photoresist underlayer film-forming polysiloxane composition is preferably 0.5% by mass, more preferably 1% by mass. On the other hand, the upper limit of the solid content concentration is preferably 20% by mass, and more preferably 10% by mass.

<Pattern formation method>

The pattern forming method of the present invention includes the following steps: a step of forming a photoresist underlayer film on one side of a substrate (hereinafter also referred to as a "photoresist underlayer film forming step"), in which the photoresist underlayer film is opposite to the substrate A step of forming a photoresist pattern on the front side (hereinafter also referred to as a "photoresist pattern forming step"), and a step of sequentially dry-etching the photoresist underlayer film and substrate using the photoresist pattern as a photomask (Hereinafter also referred to as "dry etching step"). Each step will be described below.

[Photoresist underlayer film forming step]

The photoresist underlayer film formation step is to coat the photoresist underlayer film-forming polysiloxane composition on one side of a substrate to be processed, and then heat-crosslink the polysiloxane to form a photoresist underlayer film.

The substrate to be processed may be a conventionally known substrate such as a silicon wafer or a wafer covered with aluminum.

Examples of the coating method of the photoresist underlayer film-forming polysiloxane composition include spin coating, cast coating, and roll coating. And The lower limit of the average thickness of the resulting photoresist lower layer film is preferably 0.01 μm. On the other hand, the upper limit of the average thickness is preferably 1 μm, and more preferably 0.5 μm.

After coating the polysiloxane composition for forming a photoresist underlayer film, the solvent in the coating film can also be volatilized by pre-baking (PB) as needed. The temperature of PB is appropriately selected according to the blending composition of the polysiloxane composition for forming a photoresist underlayer film, but it is preferably 30 ° C or higher and 200 ° C or lower. The PB time is preferably 5 seconds to 600 seconds.

The heating temperature after the coating of the photoresist underlayer film-forming polysiloxane composition is not particularly limited, but the lower limit thereof is preferably 100 ° C, more preferably 120 ° C, still more preferably 150 ° C, and most preferably 200 ℃. On the other hand, the upper limit of the heating temperature is preferably 450 ° C, more preferably 400 ° C, still more preferably 300 ° C, and most preferably 240 ° C.

The lower limit of the heating time is preferably 10 seconds, more preferably 15 seconds, still more preferably 20 seconds, and most preferably 40 seconds. On the other hand, the upper limit of the heating time is preferably 1 hour, more preferably 10 minutes, still more preferably 150 seconds, and most preferably 80 seconds.

By setting the heating temperature and time when the photoresist underlayer film is formed to the above-mentioned range, the photoresist underlayer film can be easily and reliably formed. In addition, the atmosphere during the heating is not particularly limited, and may be an air atmosphere or an inert gas atmosphere such as nitrogen.

In addition, before the photoresist underlayer film forming step, an organic underlayer film may be formed on the substrate to be processed, and in the photoresist underlayer film forming step, a photoresist underlayer film may be formed on the organic underlayer film. In the multilayer photoresist process, the organic substrate is placed between the substrate to be processed and the photoresist underlayer film. The layer film can further exert the effect of the present invention. This organic underlayer film can be formed by applying the composition for forming an organic underlayer film and drying it.

Furthermore, an organic anti-reflection film can be formed on the substrate to be processed, and a photoresist underlayer film or the like can be formed thereon. As this organic antireflection film, those described in, for example, Japanese Patent Publication No. 6-12452, Japanese Patent Application Publication No. 59-93448, and the like can be used.

[Photoresist Pattern Forming Step]

The photoresist pattern forming step includes, for example, a step of forming a photoresist film on the opposite side of the photoresist underlayer film from the substrate using a radiation-sensitive linear resin composition (hereinafter also referred to as a “photoresist film formation step”), A step of exposing the photoresist film (hereinafter also referred to as "exposure step"), and a step of developing the exposed photoresist film using an organic solvent (hereinafter also referred to as "developing step").

(Photoresist film formation step)

This step is to form a photoresist film by coating a radiation-sensitive linear resin composition on the opposite side of the photoresist underlayer film from the substrate.

(Radiation-sensitive resin composition)

The radiation-sensitive linear resin composition is, for example, a base polymer containing an acid dissociable group, an acid generator, and a solvent. In addition, the radiation-sensitive linear resin composition may contain other components such as a fluoropolymer and an acid diffusion control agent.

The base polymer has an acid-dissociable group. Acid dissociation The radical is a radical dissociated by an acid generated from an acid generator or the like. By dissociating the dissociable group, a carboxyl group or the like is generated in the base polymer, and a difference in solubility between the exposed portion and the unexposed portion in the developing solution occurs.

As the base polymer having the above-mentioned acid-dissociable group, a polymer contained in a generally radiation-sensitive linear resin composition can be used, and it is preferably a polymer having a structure derived from 1-alkyl-1-cycloalkyl (meth) acrylate Polymers, polymers having a structure derived from 2-cycloalkylpropane-2-yl (meth) acrylate, polymers having a structure derived from 2-alkyl-2-adamantyl (meth) acrylate A polymer having a structure derived from 2- (adamantane-1-yl) propane-2-yl (meth) acrylate.

The base polymer may have a structure such as a lactone structure, a cyclic carbonate structure, or a sultone structure. By having such a structure, the solubility of the photoresist film to the developing solution can be further improved.

The lower limit of the content of the base polymer is in the total solid content of the radiation-sensitive linear resin composition, and is preferably 70% by mass, more preferably 75% by mass, and even more preferably 80% by mass.

The contained form of the acid generator is a form of a low-molecular compound, a form in which the above-mentioned low-molecular compound is incorporated in a part of the polymer, and a form of both of them. The low-molecular compound is, for example, the same compound as the acid generator exemplified in the polysiloxane composition for forming a photoresist underlayer film. Among these, an onium salt compound is preferable, and a sulfonium salt and a tetrahydrothienium salt are more preferable.

When the acid generator is the low-molecular-weight compound, the content of the acid generator is preferably less than the lower limit of 100 parts by mass of the base polymer. 0.5 part by mass, more preferably 1 part by mass, and most preferably 3 part by mass. On the other hand, the upper limit of the content is preferably 30 parts by mass, more preferably 20 parts by mass, and even more preferably 15 parts by mass. By making the content of the acid generator into the above range, the sensitivity and developability of the radiation-sensitive resin composition can be improved. The acid generator may be used singly or in combination of two or more kinds.

Examples of the solvent include the same solvents as those exemplified in the polysiloxane composition for forming a photoresist underlayer film. Among these, ester-based solvents and ketone-based solvents are preferred, and propylene glycol monomethyl ether acetate and cyclohexanone are more preferred. These solvents can be used alone or in combination of two or more.

Examples of the acid diffusion controlling agent are the same as the nitrogen-containing compounds exemplified in the polysiloxane composition for forming a photoresist underlayer film, and a photodisintegrable base.

The photo-disintegrable base is a compound that generates a weak acid by exposure, functions as a quencher that exerts an acid-capturing function by an anion in an unexposed portion, and captures an acid that diffuses from the exposed portion. On the other hand, an acid is generated in the exposed portion and the anion is eliminated, so that it has an acid trapping function. That is, it functions only as a quencher in the unexposed portion, so the contrast of the dissociation reaction of the acid dissociable group is improved. The photo-disruptive base is, for example, an onium salt compound that is decomposed by exposure and loses control of acid diffusion. Examples of the onium salt compound include a sulfonium salt compound and a sulfonium salt compound.

The acid-diffusion controlling agent is preferably a photo-disintegrable base, more preferably triphenylphosphonium salicylate and triphenylphosphonium camphorsulfonate.

When the above-mentioned radiation-sensitive linear resin composition contains an acid diffusion controller, when the acid diffusion controller is an acid diffusion controller, The lower limit of the content with respect to 100 parts by mass of the base polymer is preferably 0.1 parts by mass, and more preferably 0.3 parts by mass. On the other hand, the upper limit of the content is preferably 10 parts by mass, more preferably 7 parts by mass, and even more preferably 5 parts by mass. When the content of the acid diffusion control agent exceeds the above-mentioned upper limit, the sensitivity of the obtained radiation-sensitive linear resin composition may decrease. The acid diffusion controlling agent can be used alone or in combination of two or more.

The coating method of the radiation-sensitive linear resin composition described above can be, for example, the same as that in the photoresist underlayer film forming step. The lower limit of the average thickness of the formed photoresist film is preferably 0.01 μm. On the other hand, the upper limit of the average thickness is preferably 1 μm, and more preferably 0.5 μm.

In addition, after coating the radiation-sensitive linear resin composition, the solvent in the coating film may be volatilized by pre-baking (PB) as necessary. The temperature and time of the PB can be set to be the same as the PB in the photoresist underlayer film.

Furthermore, in order to prevent the influence of alkaline impurities and the like contained in the ambient atmosphere, a protective film may be provided on the photoresist film formed as described above. Examples of the protective film include those described in Japanese Patent Application Laid-Open No. 5-188598. In addition, in order to prevent an acid generator or the like from flowing out of the photoresist film, a liquid immersion protective film described in, for example, Japanese Patent Application Laid-Open No. 2005-352384 may be provided on the photoresist film. It is also possible to use these technologies in combination.

(Exposure step)

In this step, the photoresist film formed in the photoresist film forming step is exposed. This exposure can be performed by, for example, reducing the projection exposure of a desired area through a contour mask to form a contour pattern. Also, it can be expected The pattern and the mask pattern are exposed twice or more. When two or more exposures are performed, continuous exposure is preferably performed. When the exposure is performed multiple times, for example, a first reduced projection exposure is performed on a desired area through a line and interval pattern mask, and then a second reduced projection exposure is performed on the exposure portion that performs the first exposure so that the lines cross. The first exposure portion and the second exposure portion are preferably orthogonal. By orthogonality, it is easy to form a perfectly round contact hole pattern in the unexposed portion surrounded by the exposed portion.

Liquid immersion exposure is performed. For the exposure, the liquid immersion liquid used in the exposure is exemplified by water or a fluorine-based inert liquid. The liquid immersion liquid is preferably a liquid that is transparent to the exposure wavelength and minimizes the temperature coefficient of the refractive index, such that the distortion of the optical image projected on the film is minimized, but the exposure light source is ArF excimer mine When emitting light (wavelength 193 nm), in addition to the above viewpoints, water is preferably used in terms of easy acquisition and easy handling. When using water, additives that reduce the surface tension of water and increase the interfacial activity can also be added in a small proportion. The additive is preferably one that does not dissolve the photoresist layer on the wafer and has a negligible effect on the optical coating under the photoresist. The water used is preferably distilled water.

The radiation used for the exposure is appropriately selected according to the type of the acid generator contained in the above sensitive radiation linear resin composition, for example, electromagnetic waves such as ultraviolet, far ultraviolet, visible light, EUV, X-ray, and γ-ray; electron beam, α Charged particle beams such as rays. Among these, far-ultraviolet rays, EUV, and electron beams are preferred, and ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV (extreme ultraviolet light), and electron beam are more preferable. Exposure conditions such as exposure amount are based on the above-mentioned sensitive radiation linearity The formulation composition of the resin composition, the type of the additive, and the like are appropriately selected. The pattern forming method may have multiple exposure steps. In this case, multiple exposures may use the same light source or different light sources.

In addition, post-exposure baking (PEB) is preferably performed after exposure. By performing PEB, the dissociation reaction of the acid dissociable group in the radiation-sensitive linear resin composition can be smoothly performed. The lower limit of the PEB temperature is preferably 30 ° C, more preferably 50 ° C, and even more preferably 70 ° C. On the other hand, the upper limit of the PEB temperature is preferably 200 ° C, more preferably 170 ° C, and still more preferably 120 ° C. The lower limit of the PEB time is preferably 5 seconds, more preferably 10 seconds. On the other hand, the upper limit of the PEB time is preferably 600 seconds, more preferably 300 seconds.

(Development steps)

In this step, a developing solution is used to develop the photoresist film exposed in the exposure step, and a drying process is performed. Thereby, a specific photoresist pattern can be formed.

When developing with an organic solvent, examples of the developing solution used for the development include organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents. Examples of the organic solvent include, for example, one or two or more of the solvents listed above as the solvent of the composition for forming a photoresist underlayer film. Among these, an ester-based solvent and a ketone-based solvent are preferred. The ester-based solvent is preferably an acetate-based solvent, and more preferably n-butyl acetate. The ketone-based solvent is preferably a chain ketone, and more preferably 2-heptanone. The lower limit of the content of the organic solvent in the developing solution is preferably 80% by mass, more preferably 90% by mass, still more preferably 95% by mass, and most preferably 99% by mass.

An appropriate amount of a surfactant may be added to the imaging solution as needed. As the surfactant, for example, an ionic or nonionic fluorine-based and / or silicon-based surfactant can be used.

Alternatively, alkaline imaging may be performed using an alkaline solution. In this case, examples of the developing solution used for the development include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, and di-n-diamine Propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo [5.4. 0] -7-undecene, 1,5-diazabicyclo [4.3.0] -5-nonene and other basic compounds in which at least one of the basic compounds is dissolved is an alkaline aqueous solution. Among these, a TMAH aqueous solution is preferable, and a 2.38 mass% TMAH aqueous solution is more preferable.

The development method includes, for example, a method of immersing a substrate in a tank filled with a developing solution for a certain period of time (immersion method), a method of using a surface tension to cause the developing solution to cover the surface of the substrate and rest for a certain period of time (overflow method), A method for spraying the developing solution on the surface of the substrate (spray method), a method for applying the developing solution to the substrate while scanning the developing solution ejection nozzle at a constant speed while rotating at a constant speed (dynamic dispersion method), and the like.

After the above development, the photoresist pattern formed is preferably washed with a washing solution. As a washing liquid, when developing an organic solvent, an alcohol-based solvent and an ester-based solvent are preferred, a monohydric alcohol-based solvent having 6 to 8 carbon atoms is more preferred, and 1-hexanol and 2-hexanol are more preferred. , 2-heptanol and 4-methyl-2-pentanol. For alkali development, water is preferred, and pure water is more preferred.

The method of cleaning treatment is, for example, a method in which a washing liquid is sprayed onto a substrate rotating at a constant speed (spin coating method), and the substrate is immersed. A method of immersing a cleaning liquid in a tank filled with a cleaning solution for a certain period of time (immersion method), a method of spraying a cleaning solution on a substrate surface (spray method), and the like.

[Dry etching step]

The dry etching step uses the photoresist pattern as a photomask, and dry-etches the photoresist underlayer film to form an underlayer pattern. Subsequently, using the lower layer pattern as a photomask, the substrate to be processed is dry-etched to form a pattern on the substrate to be processed.

This dry etching can be performed using a conventional dry etching apparatus. In addition, the etching gas used for dry etching can be appropriately selected according to the elemental composition of the photoresist underlayer film to be etched, and examples thereof include fluorine-based gases such as CHF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , and SF ₆ , Cl _2, BCl ₃ and other chlorine-based _{gas, O 2, O 3, H} 2 O and other oxygen-containing _{gas, H 2, NH 3, CO} , CO 2 and other gases, He, N _2, Ar and other inert gas. These gases can be used singly or in combination.

The etching gas used for the etching of the photoresist underlayer film is preferably a fluorine-based gas, more preferably a mixture of an oxygen-based gas and an inert gas in the fluorine-based gas. The etching gas used for etching the substrate to be processed is preferably an oxygen-based gas, and more preferably an inert gas mixed with the oxygen-based gas.

In addition, when forming the above-mentioned organic underlayer film, the dry etching step uses the above-mentioned underlayer pattern as a photomask to etch the organic underlayer film, and then etches the substrate to be processed. The etching gas used for the etching of the organic underlayer film is preferably an oxygen-based gas, and more preferably an inert gas is mixed with the oxygen-based gas.

[Example]

The present invention is described in detail below based on examples, but this example is not It is not to be construed as limiting the invention. The measurement methods of various physical property values are shown below.

[Determining the solid content content ratio]

0.5 g of the siloxane resin solution was fired at 250 ° C. for 30 minutes, and the weight of the solid content of the 0.5 g of the resin solution was measured, and the content ratio of the solid content of the siloxane resin solution was determined.

[Measurement of Mw and Mn]

The Mw and Mn of the polymer were measured by a gel permeation chromatography (GPC) under the following conditions.

Columns: 2 "G2000HXL" from TOSOH, 1 "G3000HXL" and 1 "G4000HXL"

Dissolution solvent: tetrahydrofuran

Column temperature: 40 ℃

Flow: 1.0 ml / min

Detector: Differential refractometer

Standard substance: monodisperse polystyrene

<Synthesis of Polysiloxane>

10.9 g of oxalic acid was heated and dissolved in 163.8 g of water to prepare an aqueous oxalic acid solution. Next, 252.6 g (75 mol%) of tetraethoxysilane, 33.0 g (15 mol%) of methyl trimethoxysilane, and 32.1 g of phenyltrimethoxysilane were fed to the feed tube equipped with a cooling pipe and an addition device. (10 mole%) and 507.7 g of propylene glycol monoethyl ether (PGEE) in a 5L flask. A dropping funnel for an aqueous oxalic acid solution. Next, after heating to 60 ° C in an oil bath, an oxalic acid aqueous solution was slowly added dropwise, and the mixture was reacted at 60 ° C for 4 hours. After the reaction, the flask to which the reaction solution was added was allowed to cool, and then it was set on an evaporator to distill off the methanol produced by the reaction. 692.0 g of propylene glycol monoethyl ether (PGEE) was added to the obtained solution, and then PGEE was distilled off by an evaporator to perform solvent replacement, thereby obtaining a polysiloxane-containing mixed solution (hereinafter also referred to as "polysiloxane" "Mixed solution") 846.0 g. The solid content concentration of the obtained polysiloxane mixture was measured by a firing method and was 6.9% by mass. As a result of GPC measurement, the Mw of the polysiloxane was 3,000.

<Preparation of Polysiloxane Composition for Photoresist Underlayer Film Formation>

The components used for preparing the photoresist underlayer film-forming polysiloxane composition are shown below.

[Acid generator]

B-1: Compound represented by the following formula (B-1)

B-2: Compound represented by the following formula (B-2)

B-3: Compound represented by the following formula (B-3)

B-4: Compound represented by the following formula (B-4)

B-5: Compound represented by the following formula (B-5)

B-6: Compound represented by the following formula (B-6)

B-7: Compound represented by the following formula (B-7)

[Solvent]

C-1: Propylene glycol monomethyl ether acetate (PGMEA)

C-2: Propylene glycol monoethyl ether (PGEE)

[Example 1]

In the preparation of the photoresist underlayer film-forming polysiloxane composition, a solution tank, a filter A, a filter B, a diaphragm pump (diaphragm pump), and a Teflon (registered trademark) tube (inner diameter 4 mm, 200mm) circulating filter device. Polyamide-based synthetic fiber membrane ("Filter Capsule PhotoKleen DDF Ultipleat‧P-Nylon" from Japan PALL Corporation, pore size 10nm, filter cloth area 0.53m ² ) was used as the above-mentioned filter A, and polyethylene membrane (from Japan PALL Corporation) "Filter Capsule PhotoKleen DDF PE-Kleen" with a pore diameter of 10 nm and a filter cloth area of 0.51 m ² ) was used as the filter B described above. At this time, two filters were connected with a tube (inner diameter: 4 mm, length: 100 mm) made of Teflon (registered trademark) so that the filter A was set to the upstream side and the filter B was set to the downstream side.

Next, 591 g of the prepared polysiloxane mixture was put into a solution tank. Diluted with 2.5 parts by mass of the acid generator (B-1) and 5037 parts by mass of the solvent (C-1) and 2157 parts by mass of (C-2) with respect to 100 parts by mass of the polysiloxane in the polysiloxane compound. After dissolving, the solution was subjected to cyclic filtration under normal pressure at a flow rate of 450 g / min until the number of cycles was 20, and a polysiloxane composition for forming a photoresist underlayer film of Example 1 was obtained.

<Examples 2 to 4 and Comparative Examples 1 to 3>

A polysiloxane composition for forming a photoresist underlayer film of Examples 2 to 4 and Comparative Examples 1 to 3 was obtained in the same manner as in Example 1 except that the compounds of the types and amounts used in Table 1 below were used.

<Evaluation>

Using a spin coater ("ACT12" manufactured by Tokyo Electronics Co., Ltd.), the polysiloxane composition for photoresist underlayer film formation of the above-mentioned Examples and Comparative Examples was coated on the surface of a 12-inch silicon wafer on line at 215 Baking was performed at 60 ° C. for 60 seconds to obtain a defect inspection substrate having a photoresist underlayer film having an average thickness of 33 nm. A defect inspection apparatus ("KLA 2819" of KLA TENCOR) was used for the obtained defect inspection substrate, and the number of defects was measured under the conditions of a pixel size of 0.23 μm and a threshold value of 10. The defect suppression property was evaluated as "A" when the number of defects per defect inspection substrate was 5 or less, and when it exceeded 25, it was evaluated as "B". In these evaluations, A is a pass. The number of defects and the evaluation are shown in Table 2.

As shown in Table 2, there are fewer defects in the photoresist underlayer film of the polysiloxane composition for forming a photoresist underlayer film in the examples. In contrast, the photoresist underlayer film of the polysiloxane composition for forming a photoresist underlayer film of the comparative example has many defects.

<Pattern shape>

By the following procedure, the pattern shape formed on the photoresist underlayer film was evaluated.

[Modulation of radiation-sensitive linear resin composition]

The compounds used in the synthesis of the base polymer (a-1) and the fluoropolymer (a-2) are shown below.

(Synthesis of base polymer (a-1))

12.9 g (50 mol%) of the following compound (M-1) and 17.1 g (50 mol%) of the compound (M-2) were dissolved in 60 g of methyl ethyl ketone, and then 2,2'-coupling was added. 1.77 g of azobisisobutyronitrile (AIBN) was dissolved and a monomer solution was prepared. Next, a 200 mL three-necked flask fed with 30 g of methyl ethyl ketone was blown with nitrogen for 30 minutes, and then heated to 80 ° C. while stirring the reaction kettle, and the monomer solution was added dropwise within 3 hours using a dropping funnel. A polymerization reaction was performed with the start of the dropwise addition as the polymerization start time for 6 hours. After the polymerization was completed, the polymerization reaction solution was cooled to 30 ° C. or lower with water cooling, put into 600 g of methanol, and the precipitated white powder was filtered. The filtered white powder was made into a slurry state using 150 g of methanol and washed twice, and then filtered again, and dried at 50 ° C for 17 hours to obtain a white powder base polymer (a-1) (yield 80%). As a result of ¹³ C-NMR, the content ratio of the structural unit derived from the compound (M-1) / (M-2) in the base polymer (a-1) was 49/51 (mole%). The Mw of the base polymer (a-1) was 6,900, and the Mw / Mn was 1.35.

(Synthesis of fluoropolymer (a-2))

10.4 g (30 mole%) of the following compound (M-3) and 19.6 g (70 mole%) of the compound (M-4) were dissolved in 60 g of methyl ethyl ketone, and then 2,2'-coupling was added. Nitrobis (isobutyronitrile) was 0.91 g (5 mole%) to prepare a monomer solution. Next, a 200 mL three-necked flask fed with 30 g of methyl ethyl ketone was blown with nitrogen for 30 minutes, and then heated to 80 ° C while stirring the reaction kettle, and the above-mentioned monomer solution prepared in advance was added dropwise within 3 hours using a dropping funnel . A polymerization reaction was performed with the start of the dropwise addition as the polymerization start time for 6 hours. After the polymerization was completed, the solution was cooled to 30 ° C. or lower with water cooling, put into 600 g of methanol, and the precipitated white powder was filtered. The filtered white powder was washed twice as a slurry with 150 g of methanol, and then filtered again, and dried at 50 ° C. for 12 hours to obtain a fluoropolymer (a-2) as a white powder (yield 68%). As a result of ¹³ C-NMR, the content ratio of the structural unit derived from the compound (M-3) / (M-4) in the fluoropolymer (a-2) was 31/69 (mole%). The Mw of the fluoropolymer (a-2) was 5,900, and the Mw / Mn was 1.58.

The components other than the base polymer (a-1) and the fluoropolymer (a-2) used for the preparation of the radiation-sensitive linear resin composition are shown below.

(Acid generator)

b-1: triphenylphosphonium 1,1,2,2-tetrafluoro-6- (1-adamantylcarbonyloxy) -hexane-1-sulfonate (represented by the following formula (b-1) Compound)

(Acid Diffusion Control Agent)

c-1: Triphenylphosphonium salicylate (compound represented by the following formula (c-1))

(Solvent)

d-1: propylene glycol monomethyl ether acetate

d-2: Cyclohexanone

d-3: γ-butyrolactone

(Modulation of radiation-sensitive linear resin composition (J-1))

100 parts by mass of a mixed base polymer (a-1), 3 parts by mass of a fluoropolymer (a-2), 10.8 parts by mass of an acid generator (b-1), and an acid diffusion control agent (c-1) 4.3 parts by mass and 2,185 parts by mass of the solvent (d-1), 935 parts by mass of the solvent (d-2) and 30 parts by mass of the solvent (d-3), and the radiation sensitive resin composition (J-1) was prepared.

[Formation of line and space pattern]

An anti-reflection film-forming material ("HM8006" from JSR Corporation) was spin-coated on a 12-inch silicon wafer. The spin coating system uses a coating / developing device ("CLEAN TRACK ACT12" of Tokyo Electronics Co., Ltd.) (hereinafter, the same device is used unless otherwise specified). Subsequently, an anti-reflection film having an average thickness of 100 nm was formed by performing PB (250 ° C, 60 seconds). The photoresist underlayer film-forming polysiloxane composition (S-1) of Example 1 was spin-coated on the anti-reflection film, and after PB (220 ° C, 60 seconds), it was cooled (23 ° C, 60 seconds) Seconds) forming a photoresist underlayer film having an average thickness of 30 nm. The average thickness of the photoresist underlayer film was measured using a film thickness measuring device ("M-2000D" by J.A. Woollam). Next, the radiation-sensitive linear resin composition (J-1) was spin-coated on the formed photoresist underlayer film. After PB (90 ° C, 60 seconds), it was cooled (23 ° C, 30 seconds) to an average thickness of 100 nm. Photoresist film.

Next, an ArF liquid immersion exposure apparatus ("S610C" by NIKON Corporation) was used to expose the mask with a mask size of 40nm line / 80nm interval under optical conditions of NA: 1.30 and Dipole. Perform PEB (100 ° C, 60 seconds) on the hot plate of the "CLEAN TRACK Lithius Pro-i", and after cooling (23 ° C, 30 seconds), perform flood imaging using butyl acetate as the developing solution (30 Seconds), washed with MIBC. Spin-dry at 2,000 rpm for 15 seconds to obtain a 40 nm line. / 80nm photoresist pattern evaluation substrate.

Using the obtained evaluation substrate, pattern evaluation was performed. The length measurement and observation of the photoresist pattern of the evaluation substrate were performed using a scanning electron microscope ("CG-4000" by Hitachi High-Technologies Corporation). The photoresist pattern showed no collapse or expansion at the bottom, and the pattern shape was good.

[Industrial availability]

As described above, according to the polysiloxane composition and pattern formation method for forming a photoresist underlayer film according to the present invention, defects in the photoresist underlayer film can be suppressed during a multilayer photoresist process. Accordingly, these patterns can be used for semiconductor device manufacturing and the like that are expected to be further refined in the future.

Claims (6)

A polysiloxane composition for forming a photoresistive underlayer film, which is a polysiloxane composition for forming a photoresistive underlayer film containing a polysiloxane and an acid generator, characterized in that the acid generator includes an onium cation and An acid anion, the onium cation includes a cation represented by the following formula (1-1), a cation represented by the following formula (1-2), or a combination thereof, (In the formula (1-1), R ^1a , R ^1b, and R ^{1c are} each independently a monovalent organic group having 1 to 20 carbon atoms. However, at least one of R ^1a , R ^1b, and R ^1c has an alicyclic structure. m1, m2, and m3 are each independently an integer of 0 to 3. However, m1, m2, and m3 are not all 0, and n1, n2, and n3 are each independently an integer of 0 to 2. When m1 is 2 or more, plural R ^1a It may be the same or different. When m2 is 2 or more, a plurality of R ^1b may be the same or different. When m3 is 2 or more, the plurality of R ^1c may be the same or different. In formula (1-2), R ² is a carbon. For monovalent organic groups of 1 to 20, p, q, and r are each independently an integer of 0 to 2. When p is 2 or more, a plurality of R ² may be the same or different). The polysiloxane composition for forming a photoresist underlayer film according to claim 1, wherein the sum of the atomic weights of the atoms constituting the acid anion is 350 or less. The polysiloxane composition for forming a photoresist underlayer film according to claim 1 or 2, wherein the acid anion is represented by the following formula (2-a), (In formula (2-a), R ³ is a monovalent organic group having 1 to 20 carbon atoms). The polysiloxane composition for forming a photoresist underlayer film according to claim 1 or 2, wherein the polysiloxane is a hydrolyzed condensate of a compound containing a silane compound represented by the following formula (i), [Chem. 3] R ^A _a SiX _4-a (i) (In the formula (i), R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, X is a halogen atom or -OR ^B , and R ^B is 1 to 20 carbon atoms For a monovalent organic group, a is an integer of 0 to 3, when R ^A is plural, plural R ^A may be the same or different, and when X is plural, plural X may be the same or different). A pattern forming method includes the steps of: forming a photoresist underlayer film on one side of a substrate; forming a photoresist pattern on a side of the photoresist underlayer film opposite to the substrate; and The photoresist pattern is used as a photomask to sequentially dry-etch the photoresist underlayer film and the substrate in sequence; and the photoresist underlayer film is made of polysiloxane for photoresist underlayer film formation as in any one of claims 1 to 4. Formation of alkane composition. The pattern forming method according to claim 5, wherein the step of forming the photoresist pattern includes the following steps: using a radiation-sensitive linear resin composition, forming a photoresist film on the opposite side of the photoresist underlayer film from the substrate A step of exposing the photoresist film described above, and a step of developing the exposed photoresist film using an organic solvent.