Resist underlayer film-forming composition

Abstract

The present invention provides a resist underlayer film forming composition which is capable of forming a flat film that exhibits high etching resistance, a good dry etching rate ratio and a good optical constant, while having good coverage even with respect to a so-called multileveled substrate and having a small difference in the film thickness after embedding. The present invention also provides: a method for producing a polymer that is suitable for the resist underlayer film forming composition; a resist underlayer film using the resist underlayer film forming composition; and a method for producing a semiconductor device. This resist underlayer film forming composition contains a reaction product of an aromatic compound (A) having 6 to 60 carbon atoms and a compound represented by formula (B), and a solvent. (In the formula, X represent an oxygen atom or a nitrogen atom; Y represents a single bond, an oxygen atom or a nitrogen atom; X and Y may combine with each other to form a ring; and each of R1, R2, R3 and R4 independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms or an aromatic group having 6 to 10 carbon atoms; provided that R2 is present only in cases where X is a nitrogen atom, and R4 is present only in cases where Y is a nitrogen atom.)

Description

Technical Field

[0001] The present invention relates to a resist underlayer film forming composition that exhibits high etching resistance, a good dry etching rate ratio and optical constants, has good coating properties even for a so-called stepped substrate, has a small film thickness difference after embedding, and can form a flat film, a polymer suitable for the resist underlayer film forming composition, a resist underlayer film using the resist underlayer film forming composition, and a method for manufacturing a semiconductor device.

Background Art

[0002] In recent years, resist underlayer film materials for multilayer resist processes are required to function as an antireflection film particularly for short-wavelength exposure, have appropriate optical constants, and also have etching resistance in substrate processing, and the use of polymers having repeating units containing a benzene ring has been proposed (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to thin the resist layer required with the miniaturization of the resist pattern, a lithography process is known in which at least two resist underlayer films are formed and the resist underlayer films are used as a mask material. This is a method in which at least one organic film (lower organic film) and at least one inorganic underlayer film are provided on a semiconductor substrate, the inorganic underlayer film is patterned using the resist pattern formed on the upper resist film as a mask, and the lower organic film is patterned using the pattern as a mask, and it is said that a pattern with a high aspect ratio can be formed. Examples of the materials for forming the at least two layers include combinations of organic resins (for example, acrylic resins, novolak resins) and inorganic materials (silicon resins (for example, organopolysiloxanes), inorganic silicon compounds (for example, SiON, SiO2), etc.). Furthermore, in recent years, double patterning technology that performs two lithographies and two etchings to obtain one pattern has been widely applied, and the above multilayer process is used in each process. At that time, the organic film formed after the first pattern is formed is required to have the property of flattening the step.

[0005] However, for a so-called stepped substrate with height differences and density differences in the resist pattern formed on the substrate to be processed, the coating property of the resist underlayer film forming composition is low, the film thickness difference after embedding becomes large, and there is also a problem that it is difficult to form a flat film.

[0006] The present invention has been made based on solving such problems, shows high etching resistance, a good dry etching rate ratio and optical constants, has good coating properties even for a so-called stepped substrate, has a small film thickness difference after embedding, and can form a flat film. An object of the present invention is to provide a resist underlayer film forming composition. Another object of the present invention is to provide a polymer suitable for the resist underlayer film forming composition, a resist underlayer film using the resist underlayer film forming composition, and a method for manufacturing a semiconductor device.

Means for Solving the Problems

[0007] The present invention includes the following. [1] A resist lower layer film forming composition comprising a reaction product of an aromatic compound (A) having 6 to 60 carbon atoms and a compound represented by the following formula (B), and a solvent. [Chemical formula] (In the formula, X represents an oxygen atom or a nitrogen atom, Y represents a single bond, an oxygen atom, or a nitrogen atom, X and Y may be bonded to each other to form a ring, R1, R2, R3, and R4 each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, or an aromatic group having 6 to 10 carbon atoms, R2 exists only when X is a nitrogen atom, R4 exists only when Y is a nitrogen atom.) [2] The resist lower layer film forming composition according to [1], wherein X and Y in the formula (B) are an oxygen atom or a nitrogen atom. [3] The resist lower layer film forming composition according to [1] or [2], wherein the compound represented by the formula (B) is a maleimide derivative represented by the following formula (C). [Chemical formula] (In the formula, R1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, or an aromatic group having 6 to 10 carbon atoms.) [4] The resist lower layer film forming composition according to [1], wherein the aromatic compound (A) contains one or more benzene rings, naphthalene rings, anthracene rings, pyrene rings or combinations thereof. [5] The resist lower layer film forming composition according to [1], wherein the aromatic compound (A) contains two or more benzene rings, naphthalene rings, anthracene rings, pyrene rings or combinations thereof. [6] The resist lower layer film forming composition according to any one of [1] to [5], further comprising a crosslinking agent. [7] The resist lower layer film forming composition according to any one of [1] to [6], further comprising an acid and / or an acid generator. [8] The resist underlayer film-forming composition according to [1], wherein the boiling point of the solvent is 160°C or higher. [9] A resist underlayer film, which is a fired product of a coating film composed of the resist underlayer film-forming composition according to any one of [1] to [8].

[10] A step of forming a resist underlayer film on a semiconductor substrate using the resist underlayer film-forming composition according to any one of [1] to [8], A step of forming a resist film on the formed resist underlayer film, A step of forming a resist pattern by irradiating and developing the formed resist film with light or an electron beam, A step of etching and patterning the resist underlayer film through the formed resist pattern, and A step of processing the semiconductor substrate through the patterned resist underlayer film A method for manufacturing a semiconductor device including the above steps.

[11] A copolymer of an aromatic compound (A) having 6 to 60 carbon atoms and a maleimide derivative represented by the following formula (C). [Chemical formula] (In the formula, R1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, or an aromatic group having 6 to 10 carbon atoms.)

[12] The polymer according to

[11] , wherein the aromatic compound (A) contains one or more benzene rings, naphthalene rings, anthracene rings, pyrene rings, or combinations thereof. [Advantages of the Invention]

[0008] The resist underlayer film-forming composition of the present invention not only has high etching resistance, a good dry etching rate ratio, and optical constants, but also the obtained resist underlayer film has good coating properties for a so-called stepped substrate, a small film thickness difference after embedding, forms a flat film, and enables finer substrate processing. In particular, the resist underlayer film forming composition of the present invention is effective for a lithography process in which at least two resist underlayer films for the purpose of thinning the resist film thickness are formed and the resist underlayer film is used as an etching mask.

Embodiments for Carrying Out the Invention

[0009] [Resist Underlayer Film Forming Composition] The resist underlayer film forming composition according to the present invention contains an aromatic compound (A) having 6 to 60 carbon atoms and a compound represented by the following formula (B):

Chemical formula

[0010] [Aromatic Compound (A) Having 6 to 60 Carbon Atoms]

[0011] The aromatic compound (A) having 6 to 60 carbon atoms (a) may be a monocyclic compound such as benzene, phenol, or phloroglucinol, (b) may be a condensed ring compound such as naphthalene or dihydroxynaphthalene, (c) may be a heterocyclic compound such as furan, thiophene, pyridine, or carbazole, (d) Compounds in which the aromatic rings of (a) to (c) are linked by single bonds, such as biphenyl, phenylindole, 9,9-bis(4-hydroxyphenyl)fluorene, α,α,α’,α’-tetrakis(4-hydroxyphenyl)-p-xylene, may also be used. (e) Compounds in which the aromatic rings of (a) to (d) are linked by spacers exemplified by -(CH2) n -(n = 1 to 20), -CH=CH-, -C≡C-, -N=N-, -NH-, -NR-, -NHCO-, -NRCO-, -S-, -COO-, -O-, -CO- and -CH=N-.

[0012] Examples of the aromatic compound include benzene, thiophene, furan, pyridine, pyrimidine, pyrazine, pyrrole, oxazole, thiazole, imidazole, naphthalene, anthracene, quinoline, carbazole, quinazoline, purine, indolizine, benzothiophene, benzofuran, indole, phenylindole, acridine, etc.

[0013] In addition, the aromatic compound (A) can be an aromatic compound containing an amino group, a hydroxyl group, or both. Further, the aromatic compound (A) can be an aromatic compound containing an arylamine compound, a phenol compound, or both. Preferably, it is an aromatic amine or a compound containing a phenolic hydroxyl group. Examples of the aromatic amine include aniline, diphenylamine, phenylnaphthylamine, hydroxydiphenylamine, phenylnaphthylamine, N,N’-diphenylethylenediamine, N,N’-diphenyl-1,4-phenylenediamine, etc. Examples of the compound containing a phenolic hydroxyl group include phenol, dihydroxybenzene, trihydroxybenzene, hydroxynaphthalene, dihydroxynaphthalene, trihydroxynaphthalene, tris(4-hydroxyphenyl)methane, tris(4-hydroxyphenyl)ethane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, polynuclear phenol, etc.

[0014] Examples of the above-mentioned polynuclear phenols include dihydroxybenzene, trihydroxybenzene, hydroxynaphthalene, dihydroxynaphthalene, trihydroxynaphthalene, tris(4-hydroxyphenyl)methane, tris(4-hydroxyphenyl)ethane, 2,2'-biphenol, and 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane.

[0015] The hydrogen atoms of the above-mentioned aromatic compound (A) having 6 to 60 carbon atoms may be substituted with an alkyl group having 1 to 20 carbon atoms, a condensed ring group, a heterocyclic group, a hydroxy group, an amino group, a nitro group, an ether group, an alkoxy group, a cyano group, or a carboxyl group.

[0016] Examples of the above-mentioned alkyl group having 1 to 20 carbon atoms include a linear or branched alkyl group which may or may not have a substituent, such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, isohexyl group, n-heptyl group, n-octyl group, cyclohexyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, p-tert-butylcyclohexyl group, n-decyl group, n-dodecylnonyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, and eicosyl group. Preferably, it is an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and still more preferably an alkyl group having 1 to 4 carbon atoms.

[0017] Examples of the alkyl group having 1 to 20 carbon atoms interrupted by an oxygen atom, a sulfur atom or an amide bond include those containing structural units such as -CH2-O-, -CH2-S-, -CH2-NHCO- or -CH2-CONH-. -O-, -S-, -NHCO- or -CONH- may be present in the alkyl group in one unit or two or more units. Specific examples of the alkyl group having 1 to 20 carbon atoms interrupted by -O-, -S-, -NHCO- or -CONH- units include methoxy group, ethoxy group, propoxy group, butoxy group, methylthio group, ethylthio group, propylthio group, butylthio group, methylcarbonylamino group, ethylcarbonylamino group, propylcarbonylamino group, butylcarbonylamino group, methylaminocarbonyl group, ethylaminocarbonyl group, propylaminocarbonyl group, butylaminocarbonyl group, etc. Further, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, a dodecyl group or an octadecyl group, each of which is substituted by a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a methylcarbonylamino group, an ethylcarbonylamino group, a methylaminocarbonyl group, an ethylaminocarbonyl group, etc. Preferably, they are a methoxy group, an ethoxy group, a methylthio group, an ethylthio group, and more preferably a methoxy group, an ethoxy group.

[0018] The condensed ring group is a substituent derived from a condensed ring compound, and specifically includes a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a naphthacenyl group, a triphenylenyl group, a pyrenyl group and a chrysenyl group. Among these, a phenyl group, a naphthyl group, an anthracenyl group and a pyrenyl group are preferred.

[0019] A complex ring group is a substituent derived from a complex ring compound, specifically, a thiophene group, a furan group, a pyridine group, a pyrimidine group, a pyrazine group, a pyrrole group, an oxazole group, a thiazole group, an imidazole group, a quinoline group, a carbazole group, a quinazoline group, a purine group, an indolizine group, a benzothiophene group, a benzofuran group, an indole group, an acridine group, an isoindole group, a benzimidazole group, an isoquinoline group, a quinoxaline group, a cinnoline group, a pteridine group, a chromene group (benzopyran group), an isochromene group (benzopyran group), a xanthene group, a thiazole group, a pyrazole group, an imidazoline group, and an azine group. Among these, a thiophene group, a furan group, a pyridine group, a pyrimidine group, a pyrazine group, a pyrrole group, an oxazole group, a thiazole group, an imidazole group, a quinoline group, a carbazole group, a quinazoline group, a purine group, an indolizine group, a benzothiophene group, a benzofuran group, an indole group, and an acridine group are preferred, and most preferred are a thiophene group, a furan group, a pyridine group, a pyrimidine group, a pyrrole group, an oxazole group, a thiazole group, an imidazole group, and a carbazole group.

[0020] In addition, the above aromatic compounds may be linked by a single bond or a spacer. Examples of the spacer include -(CH2) n -(n = 1 to 20), -CH<, -CH=CH-, -C≡C-, -N=N-, -NH-, -NR-, -NHCO-, -NRCO-, -S-, -COO-, -O-, -CO-, and -CH=N-, or a combination of one or more of these. Two or more of these spacers may be linked.

[0021] The above aromatic compound (A) preferably contains one or more benzene rings, naphthalene rings, anthracene rings, pyrene rings, or a combination thereof, and more preferably contains two or more benzene rings, naphthalene rings, anthracene rings, pyrene rings, or a combination thereof.

[0022] Some particularly preferred examples of the above aromatic compound (A) are as follows. [Chemical formula]

[0023] The above aromatic compound (A) may be one kind or two or more kinds, preferably one or two kinds.

[0024] [Compound represented by formula (B)] Compound (B) is represented by the following formula. [Chemical formula] (In the formula, X represents an oxygen atom or a nitrogen atom, Y represents a single bond, an oxygen atom, or a nitrogen atom, X and Y may combine with each other to form a ring, R1, R2, R3, and R4 each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, or an aromatic group having 6 to 10 carbon atoms, R2 exists only when X is a nitrogen atom, R4 exists only when Y is a nitrogen atom.)

[0025] Examples of the alkyl group having 1 to 20 carbon atoms include linear or branched alkyl groups which may or may not have a substituent, such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, isohexyl group, n-heptyl group, n-octyl group, cyclohexyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, p-tert-butylcyclohexyl group, n-decyl group, n-dodecylnonyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, and eicosyl group. Preferably, it is an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and still more preferably an alkyl group having 1 to 4 carbon atoms.

[0026] Examples of the cyclic alkyl group having 3 to 8 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group, which may or may not have a substituent.

[0027] Examples of the aromatic group having 6 to 10 carbon atoms include a group obtained by removing one hydrogen atom from an aromatic compound such as benzene, toluene, xylene, mesitylene, cumene, styrene, indene, naphthalene, azulene, anthracene, and phenanthrene, which may or may not have a substituent. Preferably, it is a benzyl group or a phenyl group.

[0028] In formula (B), R1 always exists. R2 exists when X is a nitrogen atom, but does not exist when X is an oxygen atom or when X and Y are bonded to each other to form a ring. R3 exists when Y is an oxygen atom or a nitrogen atom, but does not exist when Y is a single bond. R4 exists when Y is a nitrogen atom, but does not exist when Y is an oxygen atom, a single bond, or when X and Y are bonded to each other to form a ring.

[0029] Preferably, X and Y in the formula (B) are an oxygen atom or a nitrogen atom.

[0030] Preferably, compound (B) is a compound in which X in the formula (B) is a nitrogen atom, Y is a single bond, X and Y are bonded to each other to form a ring, and R2, R3, and R4 do not exist. That is, the compound represented by the formula (B) is a maleimide derivative represented by the following formula (C).

Chemical formula

[0031] Some particularly preferred examples of the above compound (B) are as follows. [Chemical formula]

[0032] The above compound (B) may be one kind or two or more kinds, preferably one or two kinds.

[0033] [Reaction product] By reacting the above aromatic compound (A) with the carbon-carbon double bond of the compound represented by the above formula (B), a reaction product (polymer) in which two carbon atoms of the compound represented by the above formula (B) link two of the above aromatic compounds (A) can be obtained. This reaction product is a copolymer of the above aromatic compound (A) and the compound represented by the above formula (B) (preferably a maleimide derivative represented by formula (C)). As described above, since the above aromatic compound (A) and the compound represented by the above formula (B) can each be selected from one kind or two or more kinds, the above polymer can also be a multi-component copolymer. Further, a monomer other than the above aromatic compound (A) and the compound represented by the above formula (B) may be copolymerized in an amount within a range that does not impair the effects of the present invention (for example, less than 50 mol%, less than 30 mol%, less than 20 mol%, less than 10 mol%, or less than 5 mol%).

[0034] As the acid catalyst used in the reaction, for example, mineral acids such as sulfuric acid, phosphoric acid, and perchloric acid, organic sulfonic acids such as p-toluenesulfonic acid, p-toluenesulfonic acid monohydrate, and methanesulfonic acid, and carboxylic acids such as formic acid and oxalic acid are used. The amount of the acid catalyst used is variously selected depending on the type of the acids used. Usually, it is 0.001 to 10,000 parts by mass, preferably 0.01 to 1,000 parts by mass, more preferably 0.1 to 100 parts by mass with respect to 100 parts by mass of the aromatic compound (A).

[0035] The above condensation reaction and addition reaction can be carried out without a solvent, but are usually carried out using a solvent. Any solvent that does not inhibit the reaction can be used. For example, ethers such as 1,2-dimethoxyethane, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, tetrahydrofuran, and dioxane can be mentioned.

[0036] During the reaction, a polymerization inhibitor (radical trap agent) may be added as necessary. Specific examples of the polymerization initiator include 2,6-diisobutylphenol, 3,5-di-tert-butylphenol, 3,5-di-tert-butylcresol, hydroquinone, hydroquinone monomethyl ether, pyrogallol, tert-butylcatechol, 4-methoxy-1-naphthol, and the like. When adding a polymerization inhibitor, the addition amount is preferably 1% by mass or less based on the total solid content.

[0037] The reaction temperature is usually from 40°C to 200°C. The reaction time is variously selected depending on the reaction temperature, but is usually about 30 minutes to 50 hours. The weight average molecular weight Mw of the polymer obtained as described above is usually from 500 to 1,000,000, or from 600 to 500,000.

[0038] The reaction products preferably used in the present invention will be described in the examples.

[0039] [Solvent] As the solvent of the resist underlayer film forming composition according to the present invention, any solvent that can dissolve the above reaction product can be used without particular limitation. In particular, since the resist underlayer film forming composition according to the present invention is used in a uniform solution state, considering its coating performance, it is recommended to use in combination a solvent generally used in the lithography process.

[0040] Examples of such solvents include methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, methyl isobutyl carbinol, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutyrate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, propylene glycol dibutyl ether, ethyl lactate, propyl lactate, isopropyl lactate, butyl lactate, isobutyl lactate, methyl formate, ethyl formate, propyl formate, isopropyl formate, butyl formate, isobutyl formate, amyl formate, isoamyl formate, methyl acetate, ethyl acetate, amyl acetate, isoamyl acetate, hexyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, butyl propionate, isobutyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, isopropyl butyrate,Butyl butyrate, isobutyl butyrate, ethyl hydroxyacetate, ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutyrate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-methoxybutyl acetate, 3-methoxypropyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butyrate, methyl acetoacetate, toluene, xylene, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, 2-heptanone, 3-heptanone, 4-heptanone, cyclohexanone, N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpyrrolidone, 4-methyl-2-pentanol, and γ-butyrolactone, etc. can be mentioned. These solvents can be used alone or in combination of two or more kinds.,

[0041] Also, the following compounds described in WO2018 / 131562A1 can also be used. [Chemical formula] (In formula (i), R 1 , R 2 and R 3 each represent a hydrogen atom, an oxygen atom, a sulfur atom or an alkyl group having 1 to 20 carbon atoms which may be interrupted by an amide bond, may be the same or different from each other, and may be bonded to each other to form a ring structure.)

[0042] Examples of the alkyl group having 1 to 20 carbon atoms include linear or branched alkyl groups which may or may not have substituents, such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, isohexyl group, n-heptyl group, n-octyl group, cyclohexyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, p-tert-butylcyclohexyl group, n-decyl group, n-dodecylnonyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group and eicosyl group. An alkyl group having 1 to 12 carbon atoms is preferable, an alkyl group having 1 to 8 carbon atoms is more preferable, and an alkyl group having 1 to 4 carbon atoms is still more preferable.

[0043] Examples of the alkyl group having 1 to 20 carbon atoms interrupted by an oxygen atom, a sulfur atom or an amide bond include those containing structural units of -CH2-O-, -CH2-S-, -CH2-NHCO- or -CH2-CONH-. -O-, -S-, -NHCO- or -CONH- may be present in one unit or two or more units in the alkyl group. Specific examples of the alkyl group having 1 to 20 carbon atoms interrupted by -O-, -S-, -NHCO- or -CONH- units include methoxy group, ethoxy group, propoxy group, butoxy group, methylthio group, ethylthio group, propylthio group, butylthio group, methylcarbonylamino group, ethylcarbonylamino group, propylcarbonylamino group, butylcarbonylamino group, methylaminocarbonyl group, ethylaminocarbonyl group, propylaminocarbonyl group, butylaminocarbonyl group, etc. Further, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group or octadecyl group, each of which is substituted by methoxy group, ethoxy group, propoxy group, butoxy group, methylthio group, ethylthio group, propylthio group, butylthio group, methylcarbonylamino group, ethylcarbonylamino group, methylaminocarbonyl group, ethylaminocarbonyl group, etc. Preferably, they are methoxy group, ethoxy group, methylthio group, ethylthio group, and more preferably methoxy group, ethoxy group.

[0044] Since these solvents have relatively high boiling points, they are also effective for imparting high embedding property and high planarization property to the resist underlayer film forming composition.

[0045] Specific examples of preferred compounds represented by the following formula (i) are shown below.

Chemical formula

[0046] Among the above, 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylisobutyramide, and The following formula:

Chemical formula

[0047] These solvents can be used alone or in combination of two or more. Among these solvents, those having a boiling point of 160 °C or higher are preferred, and propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl lactate, cyclohexanone, 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylisobutyramide, 2,5-dimethylhexane-1,6-diyl diacetate (DAH; cas, 89182-68-3), 1,6-diacetoxyhexane (cas, 6222-17-9), etc. are preferred. Particularly preferred are propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and N,N-dimethylisobutyramide.

[0048] [Crosslinking agent component] The resist underlayer film-forming composition of the present invention can contain a crosslinking agent component. Examples of the crosslinking agent include melamine-based, substituted urea-based, or their polymer-based ones. Preferably, it is a crosslinking agent having at least two crosslinking-forming substituents, and compounds such as methoxymethylated glycoluril (for example, tetramethoxymethyl glycoluril), butoxymethylated glycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methoxymethylated urea, butoxymethylated urea, or methoxymethylated thiourea. Also, condensates of these compounds can be used.

[0049] Also, as the above crosslinking agent, a crosslinking agent with high heat resistance can be used. As the crosslinking agent with high heat resistance, a compound containing a crosslinking-forming substituent having an aromatic ring (for example, benzene ring, naphthalene ring) in the molecule can be preferably used.

[0050] Examples of this compound include a compound having a partial structure of the following formula (4), a polymer or oligomer having a repeating unit of the following formula (5). [Chemical formula] The above R 11 , R 12 , R 13 , and R 14 are a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and the above examples can be used for these alkyl groups.

[0051] Compounds, polymers, and oligomers of formula (4) and formula (5) are exemplified below. [Chemical formula] [Chemical formula]

[0052] The above compound can be obtained as a product of Asahi Organic Materials Co., Ltd. and Honshu Chemical Industry Co., Ltd. For example, among the above crosslinking agents, the compound of formula (4-24) can be obtained from Asahi Organic Materials Co., Ltd. under the trade name TM-BIP-A. The addition amount of the crosslinking agent varies depending on the coating solvent used, the substrate used, the required solution viscosity, the required film shape, etc., but is 0.001 to 80% by mass, preferably 0.01 to 50% by mass, more preferably 0.05 to 40% by mass based on the total solid content. These crosslinking agents may cause a crosslinking reaction by self-condensation, but when crosslinkable substituents are present in the above reaction product of the present invention, they can cause a crosslinking reaction with those crosslinkable substituents.

[0053] [Acid and / or acid generator] The resist underlayer film-forming composition of the present invention can contain an acid and / or an acid generator. Examples of the acid include p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium p-toluenesulfonic acid, pyridinium phenolsulfonic acid, salicylic acid, 5-sulfosalicylic acid, 4-phenolsulfonic acid, camphorsulfonic acid, 4-chlorobenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, citric acid, benzoic acid, hydroxybenzoic acid, naphthalenecarboxylic acid, and the like. Only one kind of acid can be used, or two or more kinds can be used in combination. The blending amount is usually 0.0001 to 20% by mass, preferably 0.0005 to 10% by mass, and more preferably 0.01 to 3% by mass based on the total solid content.

[0054] Examples of the acid generator include a thermal acid generator and a photoacid generator. Examples of the thermal acid generator include 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, K-PURE [registered trademark] CXC-1612, CXC-1614, TAG-2172, TAG-2179, TAG-2678, TAG2689, TAG2700 (manufactured by King Industries), and SI-45, SI-60, SI-80, SI-100, SI-110, SI-150 (manufactured by Sanshin Chemical Industry Co., Ltd.), and other organic sulfonic acid alkyl esters.

[0055] The photoacid generator generates an acid when the resist is exposed. Therefore, the acidity of the lower layer film can be adjusted. This is one method for adjusting the acidity of the lower layer film to match the acidity of the upper layer resist. Further, by adjusting the acidity of the lower layer film, the pattern shape of the resist formed on the upper layer can be adjusted. Examples of the photoacid generator contained in the resist lower layer film forming composition of the present invention include an onium salt compound, a sulfonimide compound, and a disulfonyldiazomethane compound.

[0056] Examples of the onium salt compounds include iodonium salt compounds such as diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoronormalbutanesulfonate, diphenyliodonium perfluoronormaloctanesulfonate, diphenyliodonium camphorsulfonate, bis(4-tert-butylphenyl)iodonium camphorsulfonate, and bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate, and sulfonium salt compounds such as triphenylsulfonium hexafluoroantimonate, triphenylsulfonium nonafluoronormalbutanesulfonate, triphenylsulfonium camphorsulfonate, and triphenylsulfonium trifluoromethanesulfonate.

[0057] Examples of the sulfonimide compounds include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoronormalbutanesulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, and N-(trifluoromethanesulfonyloxy)naphthalimide.

[0058] Examples of the disulfonyldiazomethane compounds include bis(trifluoromethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(2,4-dimethylbenzenesulfonyl)diazomethane, and methylsulfonyl-p-toluenesulfonyldiazomethane.

[0059] Only one type of the acid generator can be used, or two or more types can be used in combination. When the acid generator is used, the ratio is 0.01 to 5 parts by mass, or 0.1 to 3 parts by mass, or 0.5 to 1 part by mass with respect to 100 parts by mass of the solid content of the resist underlayer film forming composition.

[0060] [Other components] In the resist underlayer film forming composition of the present invention, a surfactant can be blended in order to prevent the occurrence of pinholes, streaks, etc. and further improve the coatability with respect to surface unevenness. Examples of the surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether; polyoxyethylene alkyl aryl ethers such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether; polyoxyethylene-polyoxypropylene block copolymers; sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, and sorbitan tristearate; polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate; nonionic surfactants; Fluorine-based surfactants such as F-Top EF301, EF303, EF352 (manufactured by Tocem Products Co., Ltd., trade name), Megafac F171, F173, R-40, R-40N, R-40LM (manufactured by DIC Corporation, trade name), Fluorad FC430, FC431 (manufactured by Sumitomo 3M Limited, trade name), Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd., trade name); and organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.). The blending amount of these surfactants is usually 2.0% by mass or less, preferably 1.0% by mass or less, based on the total solid content of the resist underlayer film material. These surfactants may be used alone or in combination of two or more. When a surfactant is used, the ratio is 0.0001 to 5 parts by mass, or 0.001 to 1 part by mass, or 0.01 to 0.5 part by mass with respect to 100 parts by mass of the solid content of the resist underlayer film forming composition.

[0061] In the resist underlayer film-forming composition of the present invention, an absorbent, a rheology modifier, an adhesion aid, etc. can be added. The rheology modifier is effective in improving the fluidity of the underlayer film-forming composition. The adhesion aid is effective in improving the adhesion between the semiconductor substrate or the resist and the underlayer film.

[0062] Examples of the absorbent include commercially available absorbents described in "Technology and Market of Industrial Dyes" (published by CMC) and "Dye Handbook" (edited by the Society of Synthetic Organic Chemistry), such as C.I.Disperse Yellow 1, 3, 4, 5, 7, 8, 13, 23, 31, 49, 50, 51, 54, 60, 64, 66, 68, 79, 82, 88, 90, 93, 102, 114 and 124; C.I.Disperse Orange1, 5, 13, 25, 29, 30, 31, 44, 57, 72 and 73; C.I.Disperse Red 1, 5, 7, 13, 17, 19, 43, 50, 54, 58, 65, 72, 73, 88, 117, 137, 143, 199 and 210; C.I.Disperse Violet 43; C.I.Disperse Blue 96; C.I.Fluorescent Brightening Agent 112, 135 and 163; C.I.Solvent Orange2 and 45; C.I.Solvent Red 1, 3, 8, 23, 24, 25, 27 and 49; C.I.Pigment Green 10; C.I.Pigment Brown 2, etc. can be preferably used. The above absorbent is usually blended at a ratio of 10% by mass or less, preferably 5% by mass or less, based on the total solid content of the resist underlayer film-forming composition.

[0063] The rheology modifier is mainly added to improve the fluidity of the resist underlayer film-forming composition, and particularly to improve the film thickness uniformity of the resist underlayer film and enhance the filling property of the resist underlayer film-forming composition into the holes during the baking process. Specific examples include phthalic acid derivatives such as dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate, butyl isodecyl phthalate, etc.; adipic acid derivatives such as dinormal butyl adipate, diisobutyl adipate, diisooctyl adipate, octyl decyl adipate, etc.; maleic acid derivatives such as dinormal butyl maleate, diethyl maleate, dinonyl maleate, etc.; oleic acid derivatives such as methyl oleate, butyl oleate, tetrahydrofurfuryl oleate, etc.; or stearic acid derivatives such as normal butyl stearate, glyceryl stearate, etc. These rheology modifiers are usually blended at a ratio of less than 30% by mass based on the total solid content of the resist underlayer film-forming composition.

[0064] Next, the auxiliary agent is mainly added for the purpose of improving the adhesion between the substrate or the resist and the resist underlayer film-forming composition, and particularly to prevent the resist from peeling off during development. Specific examples include chlorosilanes such as trimethylchlorosilane, dimethylmethylolchlorosilane, methyldiphenylchlorosilane, chloromethyldimethylchlorosilane, etc.; alkoxysilanes such as trimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane, dimethylmethylolethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, etc.; silazanes such as hexamethyldisilazane, N,N'-bis(trimethylsilyl)urea, dimethyltrimethylsilylamine, trimethylsilylimidazole, etc.; silanes such as methyloltrichlorosilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, etc.; heterocyclic compounds such as benzotriazole, benzimidazole, indazole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, urazole, thiouracil, mercaptoimidazole, mercaptopyrimidine, etc.; ureas such as 1,1-dimethylurea, 1,3-dimethylurea, etc., or thiourea compounds. These adhesion auxiliary agents are usually blended in a proportion of less than 5% by mass, preferably less than 2% by mass, based on the total solid content of the resist underlayer film-forming composition.

[0065] The solid content of the resist underlayer film-forming composition according to the present invention is usually 0.1 to 70% by mass, preferably 0.1 to 60% by mass. The solid content is the content ratio of all components excluding the solvent from the resist underlayer film-forming composition. The proportion of the above reaction product in the solid content is preferably in the order of 1 to 100% by mass, 1 to 99.9% by mass, 50 to 99.9% by mass, 50 to 95% by mass, 50 to 90% by mass.

[0066] One of the scales for evaluating whether the resist underlayer film forming composition is in a uniform solution state is to observe the permeability of a specific microfilter. However, the resist underlayer film forming composition according to the present invention passes through a microfilter with a pore diameter of 0.1 μm and exhibits a uniform solution state.

[0067] Examples of the microfilter material include fluororesins such as PTFE (polytetrafluoroethylene) and PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PE (polyethylene), UPE (ultra-high molecular weight polyethylene), PP (polypropylene), PSF (polysulfone), PES (polyethersulfone), and nylon. However, it is preferably made of PTFE (polytetrafluoroethylene).

[0068] [Resist Underlayer Film and Method for Manufacturing Semiconductor Device] Hereinafter, a method for manufacturing a resist underlayer film and a semiconductor device using the resist underlayer film forming composition according to the present invention will be described.

[0069] On a substrate used in the manufacture of a semiconductor device (for example, a silicon wafer substrate, a silicon / silicon dioxide coated substrate, a silicon nitride substrate, a glass substrate, an ITO substrate, a polyimide substrate, and a low dielectric constant material (low-k material) coated substrate, etc.), the resist underlayer film forming composition of the present invention is applied by an appropriate coating method such as a spinner or a coater, and then baked to form a resist underlayer film. As the baking conditions, they are appropriately selected from a baking temperature of 80°C to 400°C and a baking time of 0.3 to 60 minutes. Preferably, the baking temperature is 150°C to 350°C and the baking time is 0.5 to 2 minutes. Here, the film thickness of the formed underlayer film is, for example, 10 to 1000 nm, or 20 to 500 nm, or 30 to 400 nm, or 50 to 300 nm.

[0070] In addition, an inorganic resist underlayer film (hard mask) can also be formed on the organic resist underlayer film according to the present invention. For example, in addition to the method of forming a silicon-containing resist underlayer film (inorganic resist underlayer film) forming composition described in WO2009 / 104552A1 by spin coating, an Si-based inorganic material film can be formed by a CVD method or the like.

[0071] Further, the resist underlayer film forming composition according to the present invention is applied onto a semiconductor substrate (so-called stepped substrate) having a portion with a step and a portion without a step, and baked, whereby a resist underlayer film can be formed in which the step between the portion with a step and the portion without a step is in the range of 3 to 70 nm.

[0072] Next, a resist film, for example, a layer of photoresist is formed on the resist underlayer film. The formation of the photoresist layer can be performed by a well-known method, that is, by applying and baking a photoresist composition solution onto the underlayer film. The film thickness of the photoresist is, for example, 50 to 10000 nm, or 100 to 2000 nm, or 200 to 1000 nm.

[0073] The photoresist formed on the resist underlayer film is not particularly limited as long as it is sensitive to the light used for exposure. Either a negative photoresist or a positive photoresist can be used. Examples of positive photoresists include those composed of a novolak resin and a 1,2-naphthoquinonediazide sulfonic acid ester, chemically amplified photoresists composed of a binder having a group that decomposes by an acid to increase the alkali dissolution rate and a photoacid generator, chemically amplified photoresists composed of a low molecular compound that decomposes by an acid to increase the alkali dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator, and chemically amplified photoresists composed of a binder having a group that decomposes by an acid to increase the alkali dissolution rate, a low molecular compound that decomposes by an acid to increase the alkali dissolution rate of the photoresist, and a photoacid generator. For example, products such as APEX-E manufactured by Shipley, PAR710 manufactured by Sumitomo Chemical Co., Ltd., and SEPR430 manufactured by Shin-Etsu Chemical Co., Ltd. can be mentioned. Further, for example, fluorine atom-containing polymer-based photoresists as described in Proc. SPIE, Vol. 3999, 330-334 (2000), Proc. SPIE, Vol. 3999, 357-364 (2000), and Proc. SPIE, Vol. 3999, 365-374 (2000) can be cited.

[0074] Next, a resist pattern is formed by irradiation with light or an electron beam and development. First, exposure is performed through a predetermined mask. For exposure, near-ultraviolet light, far-ultraviolet light, or extreme ultraviolet light (e.g., EUV (wavelength 13.5 nm)) etc. are used. Specifically, a KrF excimer laser (wavelength 248 nm), an ArF excimer laser (wavelength 193 nm), an F2 excimer laser (wavelength 157 nm), etc. can be used. Among these, an ArF excimer laser (wavelength 193 nm) and EUV (wavelength 13.5 nm) are preferred. After exposure, post exposure bake can also be performed as necessary. The post exposure bake is carried out under conditions appropriately selected from a heating temperature of 70°C to 150°C and a heating time of 0.3 to 10 minutes.

[0075] In the present invention, an electron beam lithography resist can be used instead of a photoresist as the resist. As the electron beam resist, either a negative type or a positive type can be used. There are chemically amplified resists composed of an acid generator and a binder having a group that decomposes with an acid to change the alkali dissolution rate, chemically amplified resists composed of an alkali-soluble binder, an acid generator, and a low-molecular compound that decomposes with an acid to change the alkali dissolution rate of the resist, chemically amplified resists composed of an acid generator and a binder having a group that decomposes with an acid to change the alkali dissolution rate and a low-molecular compound that decomposes with an acid to change the alkali dissolution rate of the resist, non-chemically amplified resists composed of a binder having a group that decomposes with an electron beam to change the alkali dissolution rate, non-chemically amplified resists composed of a binder having a site that is cleaved by an electron beam to change the alkali dissolution rate, and the like. When these electron beam resists are used, a resist pattern can be formed in the same manner as when a photoresist is used with an electron beam as the irradiation source.

[0076] Subsequently, development is carried out with a developer. Thereby, for example, when a positive photoresist is used, the photoresist in the exposed portion is removed, and a pattern of the photoresist is formed. Examples of the developer include aqueous solutions of alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline, and aqueous alkaline solutions such as aqueous amine solutions of ethanolamine, propylamine, and ethylenediamine. Furthermore, a surfactant or the like can be added to these developers. The development conditions are appropriately selected from a temperature of 5 to 50°C and a time of 10 to 600 seconds.

[0077] Then, the inorganic lower layer film (intermediate layer) is removed using the pattern of the photoresist (upper layer) thus formed as a protective film, and then the film composed of the patterned photoresist and the inorganic lower layer film (intermediate layer) is used as a protective film to remove the organic lower layer film (lower layer). Finally, the semiconductor substrate is processed using the patterned inorganic lower layer film (intermediate layer) and the organic lower layer film (lower layer) as a protective film.

[0078] First, the inorganic lower layer film (intermediate layer) in the portion where the photoresist has been removed is removed by dry etching to expose the semiconductor substrate. For the dry etching of the inorganic lower layer film, gases such as tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, sulfur hexafluoride, difluoromethane, nitrogen trifluoride and chlorine trifluoride, chlorine, trichloroborane and dichloroborane can be used. It is preferable to use a halogen-based gas for the dry etching of the inorganic lower layer film, and it is more preferable to use a fluorine-based gas. Examples of the fluorine-based gas include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, and difluoromethane (CH2F2).

[0079] Thereafter, the organic lower layer film is removed using the film composed of the patterned photoresist and the inorganic lower layer film as a protective film. The organic lower layer film (lower layer) is preferably removed by dry etching with an oxygen-based gas. This is because the inorganic lower layer film containing a large amount of silicon atoms is difficult to remove by dry etching with an oxygen-based gas.

[0080] Finally, the semiconductor substrate is processed. The processing of the semiconductor substrate is preferably performed by dry etching with a fluorine-based gas. Examples of the fluorine-based gas include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, and difluoromethane (CH2F2).

[0081] Further, an organic antireflection film can be formed on the upper layer of the resist underlayer film before forming the photoresist. The antireflection film composition used therefor is not particularly limited, and it can be arbitrarily selected from those conventionally used in the lithography process and used. Also, the antireflection film can be formed by a conventionally used method, for example, by coating with a spinner or a coater and baking.

[0082] In the present invention, after forming an organic underlayer film on a substrate, an inorganic underlayer film can be formed thereon, and further a photoresist can be coated thereon. Thereby, the pattern width of the photoresist becomes narrow, and even when the photoresist is thinly coated to prevent pattern collapse, the substrate can be processed by selecting an appropriate etching gas. For example, a fluorine-based gas having an etching rate sufficiently fast for the photoresist can be used as the etching gas to process the resist underlayer film, and a fluorine-based gas having an etching rate sufficiently fast for the inorganic underlayer film can be used as the etching gas to process the substrate. Further, the substrate can be processed by using an oxygen-based gas having an etching rate sufficiently fast for the organic underlayer film as the etching gas.

[0083] The resist underlayer film formed from the resist underlayer film forming composition may also have absorption for the light depending on the wavelength of the light used in the lithography process. And in such a case, it can function as an antireflection film having an effect of preventing reflected light from the substrate. Further, the underlayer film formed of the resist underlayer film forming composition of the present invention can also function as a hard mask. The underlayer film of the present invention has a function of preventing the interaction between the substrate and the photoresist, a function of preventing the adverse action of the substance generated when exposed to the photoresist or the substance used for the photoresist on the substrate, a function of preventing the diffusion of the substance generated from the substrate during heat baking to the upper photoresist, and can also be used as a barrier layer for reducing the poisoning effect of the photoresist layer by the semiconductor substrate dielectric layer.

[0084] In addition, the lower layer film formed from the resist lower layer film forming composition can be applied to a substrate on which via holes used in a dual damascene process are formed, and can be used as an embedding material that can fill the holes without gaps. It can also be used as a planarizing material for planarizing the surface of a semiconductor substrate with irregularities.

Example

[0085] Hereinafter, specific examples of the resist lower layer film forming composition of the present invention will be described using the following examples, but the present invention is not limited thereby.

[0086] The apparatus and the like used for measuring the weight average molecular weight of the reaction product obtained in the following synthesis example are shown. Apparatus: HLC-8320GPC manufactured by Tosoh Corporation GPC column: TSKgel Super-Multipore HZ-N (two pieces) Column temperature: 40°C Flow rate: 0.35 ml / min Eluent: THF Standard sample: Polystyrene (manufactured by Showa Denko K.K.)

[0087] <Synthesis Example 1> To 16.75 g of propylene glycol monomethyl ether (hereinafter abbreviated as PGME in this specification), 5.00 g of TEP-TPA (manufactured by Asahi Organic Chemical Industry Co., Ltd.), 7.55 g of N-cyclohexylmaleimide (manufactured by Tokyo Chemical Industry Co., Ltd.), and 4.05 g of methanesulfonic acid as a catalyst were added, and then the mixture was reacted at 140°C for 7 hours to obtain a solution containing the reaction product. After dilution to a 30% by mass solution with PGME, reprecipitation was performed using a methanol / water mixed solvent (200 g). The obtained precipitate was filtered and dried in a vacuum dryer at 60°C for 24 hours to obtain the target polymer. When GPC analysis of the reaction product was performed, the weight average molecular weight in terms of standard polystyrene was 11,500. The obtained reaction product was presumed to be a copolymer having a structural unit represented by the following formula (1).

Chemical formula

[0088] <Synthesis Example 2> To 17.22 g of PGME, 7.00 g of TEP-TPA (manufactured by Asahi Organic Chemical Industry Co., Ltd.), 7.38 g of N-ethylmaleimide (manufactured by Tokyo Chemical Industry Co., Ltd.), and 2.84 g of methanesulfonic acid as a catalyst were added, and then the mixture was reacted at 140 °C for 7 hours to obtain a solution containing the reaction product. After dilution to a 30% by mass solution with PGME, reprecipitation was carried out using a methanol / water mixed solvent (200 g, mass mixing ratio 50 / 50). The obtained precipitate was filtered and dried in a vacuum dryer at 60 °C for 24 hours to obtain the target polymer. When GPC analysis of the reaction product was performed, the weight average molecular weight in terms of standard polystyrene was 9,000. The obtained reaction product was presumed to be a copolymer having a structural unit represented by the following formula (2). [Chemical Formula]

[0089] <Synthesis Example 3> To 20.06 g of PGME, 8.00 g of 2,2'-dihydroxybiphenyl (manufactured by Tokyo Chemical Industry Co., Ltd.), 7.70 g of N-cyclohexylmaleimide (manufactured by Tokyo Chemical Industry Co., Ltd.), 4.13 g of methanesulfonic acid as a catalyst, and 0.24 g of hydroquinone as a radical trap agent were added, and then the mixture was reacted at 140 °C for 20 hours to obtain a solution containing the reaction product. After dilution to a 30% by mass solution with PGME, reprecipitation was carried out using a methanol / water mixed solvent (600 g, mass mixing ratio 50 / 50). The obtained precipitate was filtered and dried in a vacuum dryer at 60 °C for 24 hours to obtain the target polymer. After adjusting to a 20% by mass solution with PGME, 16.00 g of an anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachi Technos Co., Ltd.) and 16.00 g of a cation exchange resin (product name: Amberlyst [registered trademark] 15JWET, Organo Co., Ltd.) were added, and the mixture was stirred at 25 °C to 30 °C for 4 hours and then filtered. When the GPC analysis of the reaction product was carried out, the weight-average molecular weight in terms of standard polystyrene was 680. The obtained reaction product was presumed to be a copolymer having a structural unit represented by the following formula (3).

Chemical formula

[0090] <Synthesis Example 4> To 21.28 g of PGME, 8.00 g of diphenylamine (manufactured by Tokyo Chemical Industry Co., Ltd.), 8.47 g of N-cyclohexylmaleimide (manufactured by Tokyo Chemical Industry Co., Ltd.), 4.54 g of methanesulfonic acid as a catalyst, and 0.26 g of hydroquinone as a radical trap agent were added, and then the mixture was reacted at 140 °C for 20 hours to obtain a solution containing the reaction product. After diluting to a 30 mass% solution with PGME, reprecipitation was carried out using a methanol / water mixed solvent (600 g, mass mixing ratio 70 / 30). The obtained precipitate was filtered and dried in a vacuum dryer at 60 °C for 24 hours to obtain the target polymer. When the GPC analysis of the reaction product was carried out, the weight-average molecular weight in terms of standard polystyrene was 1,360. The obtained reaction product was presumed to be a copolymer having a structural unit represented by the following formula (4).

Chemical formula

[0091] <Synthesis Example 5> To 167.27 g of propylene glycol monomethyl ether acetate (hereinafter abbreviated as PGMEA in this specification), 50.00 g of N-phenyl-1-naphthylamine (manufactured by Tokyo Chemical Industry Co., Ltd.), 20.43 g of N-cyclohexylmaleimide (manufactured by Tokyo Chemical Industry Co., Ltd.), 21.91 g of methanesulfonic acid as a catalyst, and 1.26 g of hydroquinone as a radical trap agent were added, and then the reaction was carried out at 140 °C for 24 hours to obtain a solution containing the reaction product. Reprecipitation was carried out using methanol (2,300 g). The obtained precipitate was filtered and dried in a vacuum dryer at 60 °C for 24 hours to obtain the target polymer. After adjusting to a 20% by mass solution with PGMEA, 70.00 g of an anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachi Technos Co., Ltd.) and 70.00 g of a cation exchange resin (product name: Amberlyst [registered trademark] 15JWET, Organo Co., Ltd.) were added, and after stirring at 25 °C to 30 °C for 4 hours, the mixture was filtered. When GPC analysis of the reaction product was performed, the weight average molecular weight in terms of standard polystyrene was 2,000. The obtained reaction product was presumed to be a copolymer having a structural unit represented by the following formula (5). [Chemical formula]

[0092] <Synthesis Example 6> To 54.91 g of PGME, 15.00 g of carbazole (manufactured by Tokyo Chemical Industry Co., Ltd.), 8.04 g of N-cyclohexylmaleimide (manufactured by Tokyo Chemical Industry Co., Ltd.), 8.62 g of methanesulfonic acid as a catalyst, and 0.49 g of hydroquinone as a radical trap agent were added. After reacting at 140 °C for 23 hours, a solution containing the reaction product was obtained. It was reprecipitated using methanol (2,800 g). The obtained precipitate was filtered and dried in a vacuum dryer at 60 °C for 24 hours to obtain the target polymer. After adjusting to a 20% by mass solution with PGMEA, 23.00 g of an anion exchange resin (product name: Dowex® MONOSPHERE® 550A, Muromachi Technos Co., Ltd.) and 23.00 g of a cation exchange resin (product name: Amberlyst® 15JWET, Organo Co., Ltd.) were added, stirred at 25 °C to 30 °C for 4 hours, and then filtered. When GPC analysis of the reaction product was performed, the weight average molecular weight in terms of standard polystyrene was 6,000. The obtained reaction product was presumed to be a copolymer having a structural unit represented by the following formula (6).

Chemical formula

[0093] <Synthesis Example 7> To 292 g of PGMEA, 50.0 g of ethylcarbazole (manufactured by Tokyo Chemical Industry Co., Ltd.), 24.9 g of maleimide (manufactured by Tokyo Chemical Industry Co., Ltd.), 24.6 g of methanesulfonic acid as a catalyst, and 1.41 g of hydroquinone as a radical trap agent were added. After reacting at 140 °C for 23 hours, a solution containing the reaction product was obtained. It was reprecipitated using methanol (3,600 g). The obtained precipitate was filtered and dried in a vacuum dryer at 60 °C for 24 hours to obtain the target polymer. After adjusting to a 20% by mass solution with PGMEA, 100.00 g of an anion exchange resin (product name: Dowex® MONOSPHERE® 550A, Muromachi Technos Co., Ltd.) and 100.00 g of a cation exchange resin (product name: Amberlyst® 15JWET, Organo Co., Ltd.) were added, stirred at 25 °C to 30 °C for 4 hours, and then filtered. When the GPC analysis of the reaction product was carried out, the weight average molecular weight in terms of standard polystyrene was 1,200. The obtained reaction product was presumed to be a copolymer having a structural unit represented by the following formula (7).

Chemical formula

[0094] <Comparative Synthesis Example 1> To 7.57 g of PGME, 17.67 g of PGMEA, 5.00 g of product name: EHPE-3150 (manufactured by Daicel Corporation), 3.11 g of 9-anthracenecarboxylic acid, 2.09 g of benzoic acid, and 0.62 g of ethyltriphenylphosphonium bromide were added, and the mixture was heated under reflux for 13 hours under a nitrogen atmosphere. To the obtained solution, 16 g of a cation exchange resin (product name: Amberlyst [registered trademark] 15JWET, manufactured by Organo Corporation) and 16 g of an anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, manufactured by Murotachi Technos Co., Ltd.) were added, and the mixture was stirred at 25°C to 30°C for 4 hours and then filtered. When the GPC analysis of the obtained reaction product was carried out, the weight average molecular weight in terms of standard polystyrene was 4,700. The obtained reaction product was presumed to be a copolymer having a structural unit represented by the following formula (8).

Chemical formula

[0095] 〔Preparation of resist underlayer film forming composition〕 <Example 1> To 0.80 g of the copolymer obtained in Synthesis Example 1, 6.36 g of PGME, 2.76 g of PGMEA, and 0.080 g of a 1 mass% PGME solution of a surfactant (product name: R-30N, manufactured by DIC Corporation) were mixed to obtain an 8.0 mass% solution. The solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a resist underlayer film forming composition.

[0096] <Example 2> To 0.80 g of the copolymer obtained in Synthesis Example 2, 6.36 g of PGME, 2.76 g of PGMEA, and 0.080 g of a 1 mass% PGME solution of a surfactant (trade name: R-30N, manufactured by DIC Corporation) were mixed to obtain an 8.0 mass% solution. The solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a resist underlayer film-forming composition.

[0097] <Example 3> To 2.86 g of a solution containing 0.55 g of the copolymer obtained in Synthesis Example 3 (the solvent was PGME used during synthesis, and the solid content was 20.54 mass%), 0.15 g of tetramethoxymethyl glycoluril (product name: POWDERLINK® 1174, manufactured by Nippon Cytec Industries Co., Ltd.), 1.47 g of a 1 mass% PGME solution of pyridinium phenolsulfonic acid (manufactured by Midori Chemical Co., Ltd.), 2.69 g of PGME, 2.78 g of PGMEA, and 0.059 g of a 1 mass% PGME solution of a surfactant (trade name: R-30N, manufactured by DIC Corporation) were mixed to obtain a 7.5 mass% solution. The solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a resist underlayer film-forming composition.

[0098] <Example 4> To 0.55 g of the copolymer obtained in Synthesis Example 4, 0.14 g of tetramethoxymethyl glycoluril (product name: POWDERLINK® 1174, manufactured by Nippon Cytec Industries Co., Ltd.), 1.37 g of a 1 mass% PGME solution of pyridinium phenolsulfonic acid (manufactured by Midori Chemical Co., Ltd.), 5.10 g of PGME, 2.79 g of PGMEA, and 0.055 g of a 1 mass% PGME solution of a surfactant (trade name: R-30N, manufactured by DIC Corporation) were mixed to obtain a 7.0 mass% solution. The solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a resist underlayer film-forming composition.

[0099] <Example 5> To 11.01 g of a solution containing 1.88 g of the copolymer obtained in Synthesis Example 5 (the solvent was PGMEA and the solid content was 17.08% by mass), 0.47 g of TMOM-BP (a compound of the following formula, manufactured by Honshu Chemical Industry Co., Ltd.), 4.70 g of a 1% by mass PGME solution of pyridinium phenolsulfonic acid (manufactured by Midori Chemical Co., Ltd.), 10.19 g of PGME, 3.44 g of PGMEA, and 0.19 g of a 1% by mass PGME solution of a surfactant (manufactured by DIC Corporation, trade name: R-30N) were mixed to obtain an 8.0% by mass solution. The solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a resist underlayer film-forming composition.

[0100]

Chemical formula

[0101] <Example 6> To 11.56 g of a solution containing 1.88 g of the copolymer obtained in Synthesis Example 6 (the solvent was PGMEA and the solid content was 16.27% by mass), 0.47 g of TMOM-BP (manufactured by Honshu Chemical Industry Co., Ltd.), 4.70 g of a 1% by mass PGME solution of pyridinium phenolsulfonic acid (manufactured by Midori Chemical Co., Ltd.), 9.64 g of PGME, 3.44 g of PGMEA, and 0.19 g of a 1% by mass PGME solution of a surfactant (manufactured by DIC Corporation, trade name: R-30N) were mixed to obtain an 8.0% by mass solution. The solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a resist underlayer film-forming composition.

[0102] <Example 7> To 10.028 g of a solution containing 1.96 g of the copolymer obtained in Synthesis Example 7 (solvent: PGMEA, solid content: 19.60% by mass), 0.39 g of TMOM-BP (manufactured by Honshu Chemical Industry Co., Ltd.), 1.96 g of a 2% by mass PGME solution of TAG2689 (manufactured by King, a thermal acid generator), 6.35 g of PGME, 11.06 g of PGMEA, and 0.19 g of a 1% by mass PGMEA solution of a surfactant (manufactured by DIC Corporation, trade name: R-30N) were mixed to obtain an 8.0% by mass solution. The solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a resist underlayer film forming composition.

[0103] <Comparative Example 1> To 19.52 g of a solution containing 4.51 g of the copolymer obtained in Comparative Synthesis Example 1 (solvent: PGME / PGMEA mixed solvent used during synthesis, solid content: 23.26% by mass), 1.14 g of tetramethoxymethyl glycoluril (product name: POWDERLINK [registered trademark] 1174, manufactured by Nippon Cytec Industries Co., Ltd.), 3.41 g of a 1% by mass PGME solution of pyridinium p-toluenesulfonate, 50.68 g of PGME, 14.80 g of PGMEA, and 0.45 g of a 1% by mass PGME solution of a surfactant (manufactured by DIC Corporation, trade name: R-30) were mixed to obtain a 6.35% by mass solution. The solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a resist underlayer film forming composition.

[0104] 〔Elution test in a photoresist solvent〕 The resist underlayer film forming compositions prepared in Examples 1 to 7 and Comparative Example 1 were each applied onto a silicon wafer using a spinner. Thereafter, baking was performed on a hot plate at the temperature shown in Table 1 below for 1 minute to form a resist underlayer film (film thickness: 0.2 μm). These resist underlayer films were immersed in a PGME / PGMEA mixed solvent (mass mixing ratio 70 / 30), which is the solvent used in the photoresist solution, and it was confirmed that they were insoluble in the solvent. The results are shown as "○" in Table 1 below.

[0105] 〔Test of optical parameters〕 The resist underlayer film-forming compositions prepared in Examples 1 to 7 and Comparative Example 1 were each applied onto a silicon wafer by a spinner. Thereafter, they were baked on a hot plate at the temperatures shown in Table 1 below for 1 minute to form resist underlayer films (film thickness: 0.2 μm). Using an ellipsometer (VUV-VASE VU-302 manufactured by J.A. Woollam), the refractive index (n value) and extinction coefficient (k value) at a wavelength of 193 nm of these resist underlayer films were measured. The results are shown in Table 1 below. In order for the resist underlayer film to have a sufficient antireflection function, it is desirable that the k value at a wavelength of 193 nm be 0.1 or more.

[0106] [Measurement of Dry Etching Rate] Using the resist underlayer film-forming compositions prepared in Examples 1 to 7 and Comparative Example 1, resist underlayer films were formed on a silicon wafer in the same manner as above. Then, the dry etching rates of these resist underlayer films were measured using an RIE system manufactured by Samco Inc. under the condition of using CF4 as a dry etching gas. When the dry etching rate of Comparative Example 1 was set to 1.00, the dry etching rates of the respective resist underlayer films were calculated. The results are shown as "relative dry etching rate" in Table 1 below. Since the dry etching rates of the resist underlayer films formed using the resist underlayer film-forming compositions prepared in Examples 1 to 7 are sufficiently slower than the dry etching rate of Comparative Example 1, it was shown that substrate processing is easy using this resist underlayer film-forming composition as a mask.

[0107]

Table 1

[0108] [Evaluation of Embedding Property] The embedding property was confirmed in a dense pattern area with a SiO2 substrate having a film thickness of 200 nm, a trench width of 50 nm, and a pitch of 100 nm. After applying the resist underlayer film-forming composition prepared in Example 1 to Example 6 and Comparative Example 1 on the above substrate, it was baked at 250 °C for 60 seconds to form a resist underlayer film of about 200 nm. The flatness of this substrate was observed using a scanning electron microscope (S-4800) manufactured by Hitachi High-Technologies Corporation, and the presence or absence of filling of the resist underlayer film-forming composition into the pattern was confirmed. As a result, Examples 1 to 6 were good, but voids were confirmed in Comparative Example 1.

[0109] [Coating Test on Step Substrate] As an evaluation of the step coverage property, the film thickness of the coating on a dense pattern area (DENSE) with a trench width of 50 nm and a pitch of 100 nm and an open area (OPEN) where no pattern was formed on a SiO2 substrate with a film thickness of 200 nm was compared. After applying the resist underlayer film-forming compositions of Example 5 and Comparative Example 1 on the above substrate with a film thickness of 150 nm, it was baked at a predetermined temperature. The step coverage property of this substrate was observed using a scanning electron microscope (S-4800) manufactured by Hitachi High-Technologies Corporation, and the film thickness difference (the coating step between the dense area (pattern part) and the open area (patternless part) of the step substrate, called Bias) was measured to evaluate the flatness. The film thickness and coating step values in each area are shown in Table 2. The smaller the value of Bias in the flatness evaluation, the higher the flatness.

[0110]

Table 2

Industrial Applicability

[0111] According to the present invention, there are provided a resist underlayer film forming composition that exhibits high etching resistance, a good dry etching rate ratio and optical constants, has good coating properties even for a so-called stepped substrate, has a small film thickness difference after embedding, and can form a flat film, a polymer suitable for the resist underlayer film forming composition, a resist underlayer film using the resist underlayer film forming composition, and a method for manufacturing a semiconductor device.

Claims

1. An aromatic compound (A) having 6 to 60 carbon atoms selected from the following compound groups [Chemical Formula 5] A resist lower layer film forming composition comprising a reaction product of the maleimide derivative represented by the following formula (C) and a solvent. [Chemical Formula 2] (In the formula, R1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, or an aromatic group having 6 to 10 carbon atoms.)

2. The resist lower layer film forming composition according to claim 1, further comprising a crosslinking agent.

3. The resist lower layer film forming composition according to claim 1 or 2, further comprising an acid and / or an acid generator.

4. The resist lower layer film forming composition according to claim 1, wherein the boiling point of the solvent is 160°C or higher.

5. A resist lower layer film, characterized in that it is a fired product of a coating film composed of the resist lower layer film forming composition according to any one of claims 1 to 4.

6. A step of forming a resist lower layer film on a semiconductor substrate using the resist lower layer film forming composition according to any one of claims 1 to 4, A step of forming a resist film on the formed resist lower layer film, A step of forming a resist pattern by irradiating and developing the formed resist film with light or an electron beam, A step of etching and patterning the resist lower layer film through the formed resist pattern, and A step of processing a semiconductor substrate through the patterned resist lower layer film A method for manufacturing a semiconductor device including.

7. A copolymer of an aromatic compound (A) having 6 to 60 carbon atoms selected from the following compound groups 【Chemical Formula 5】 And a maleimide derivative represented by the following formula (C). 【Chemical Formula 3】 (In the formula, R1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, or an aromatic group having 6 to 10 carbon atoms.)

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