Composition for forming resist underlayer film containing polycyclic aromatic polymer

Abstract

To provide a resist underlayer film that can improve LWR of resist patterns, a composition for resist underlayer film formation for EB or EUV lithography, a resist underlayer film for EB or EUV lithography, a substrate for semiconductor processing, a method for producing a semiconductor element, a patterning method, and a method for improving LWR of resist patterns.SOLUTION: A composition for resist underlayer film formation includes a polymer having at least either a unit structure (A) having a polycyclic aromatic hydrocarbon structure or a unit structure (B) derived from a maleimide structure. A resist underlayer film is a burned coating film from the inventive composition for resist underlayer film formation, wherein the resist underlayer film has a film thickness of less than 10 nm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resist underlayer film, a composition for forming a resist underlayer film for EB or EUV lithography, a substrate for semiconductor processing, a method for manufacturing a semiconductor element, a pattern forming method, and a method for improving LWR of a resist pattern. [Background technology]

[0002] 2. Description of the Related Art In semiconductor devices such as LSIs (semiconductor integrated circuits), the formation of finer patterns is required as the degree of integration increases, and in recent years the minimum pattern size has reached 100 nm or less. The formation of such fine patterns in semiconductor devices has been made possible by shortening the wavelength of the light source in exposure equipment and improving resist materials. Currently, immersion lithography is used, in which exposure is performed through water using deep ultraviolet ArF (argon fluoride) excimer laser light with a wavelength of 193 nm, and various ArF-compatible resist materials based on acrylic resins have been developed.

[0003] Furthermore, as next-generation exposure technologies, research is underway into electron beam (EB) exposure methods, and extreme ultraviolet (EUV) exposure methods, which use soft X-rays with a wavelength of 13.5 nm as a light source, and pattern sizes are expected to become even smaller, reaching 30 nm or less. However, as pattern sizes become smaller, line edge roughness (LER) on the resist pattern sidewalls and line width roughness (LWR) on the resist pattern width increase, raising concerns that these problems may adversely affect device performance. While efforts have been made to suppress these problems by optimizing exposure tools, resist materials, and process conditions, satisfactory results have not been achieved. Furthermore, LWR and LER are related, and improving LWR also improves LER.

[0004] As a method for solving the above problems, a method has been disclosed in which the resist pattern is treated with an aqueous solution containing a specific ionic surfactant in a rinsing step after the development process, thereby suppressing defects (such as residue generation and pattern collapse) caused by the development process and dissolving the unevenness of the resist pattern, thereby improving the LWR and LER (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-213013 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a resist underlayer film, a composition for forming a resist underlayer film for EB or EUV lithography, a resist underlayer film for EB or EUV lithography, a substrate for semiconductor processing, a method for manufacturing a semiconductor element, a pattern formation method, and a method for improving LWR of a resist pattern, which are capable of improving LWR of a resist pattern. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the above problems can be solved, and have completed the present invention having the following gist. That is, the present invention includes the following. [1] A resist underlayer film that is a fired product of a coating film of a composition for forming a resist underlayer film, The composition for forming a resist underlayer film contains a polymer having at least one unit structure selected from the group consisting of a unit structure (A) having a polycyclic aromatic hydrocarbon structure and a unit structure (B) having a maleimide structure, The resist underlayer film has a film thickness of less than 10 nm. [2] The resist underlayer film according to [1], wherein the polycyclic aromatic hydrocarbon structure in the unit structure (A) includes at least one structure selected from the group consisting of naphthalene, anthracene, phenanthrene, carbazole, pyrene, triphenylene, chrysene, naphthacene, biphenylene, and fluorene. [3] The resist underlayer film according to [1] or [2], wherein the unit structure (B) is represented by the following formula (4): [ka] (In formula (4), R 2 represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be substituted with a hydroxy group, or an aryl group having 6 to 10 carbon atoms which may be substituted with a halogen atom. [4] The resist underlayer film according to any one of [1] to [3], wherein the polymer further comprises a unit structure (C) having a crosslinking group. [5] The resist underlayer film according to [4], wherein the crosslinking group in the unit structure (C) includes at least one group selected from the group consisting of a hydroxy group, an epoxy group, a protected hydroxy group, and a protected carboxy group. [6] The resist underlayer film according to any one of [1] to [5], wherein the composition for forming a resist underlayer film further contains a crosslinking agent. [7] The resist underlayer film according to any one of [1] to [6], wherein the composition for forming a resist underlayer film further contains a curing catalyst. [8] The resist underlayer film according to any one of [1] to [7], which is a resist underlayer film for EB or EUV lithography. [9] A composition for forming a resist underlayer film for EB or EUV lithography, comprising a polymer having at least one unit structure selected from the group consisting of a unit structure (A) having a polycyclic aromatic hydrocarbon structure and a unit structure (B) having a maleimide structure.

[10] The composition for forming a resist underlayer film for EB or EUV lithography according to [9], wherein the polycyclic aromatic hydrocarbon structure in the unit structure (A) comprises at least one structure selected from the group consisting of naphthalene, anthracene, phenanthrene, carbazole, pyrene, triphenylene, chrysene, naphthacene, biphenylene, and fluorene.

[11] The composition for forming a resist underlayer film for EB or EUV lithography according to [9] or

[10] , wherein the unit structure (B) is represented by the following formula (4): [ka] (In formula (4), R 2 represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be substituted with a hydroxy group, or an aryl group having 6 to 10 carbon atoms which may be substituted with a halogen atom.

[12] The composition for forming a resist underlayer film for EB or EUV lithography according to any one of [9] to

[11] , wherein the polymer further has a unit structure (C) having a crosslinking group.

[13] The composition for forming a resist underlayer film for EB or EUV lithography according to

[12] , wherein the crosslinking group in the unit structure (C) includes at least one group selected from the group consisting of a hydroxy group, an epoxy group, a protected hydroxy group, and a protected carboxy group.

[14] The composition for forming a resist underlayer film for EB or EUV lithography according to any one of [9] to

[13] , further comprising a crosslinking agent.

[15] The composition for forming a resist underlayer film for EB or EUV lithography according to any one of [9] to

[14] , further comprising a curing catalyst.

[16] A composition for forming a resist underlayer film for EB or EUV lithography according to any one of claims 9 to 15, which is used to form the resist underlayer film according to any one of [1] to [8].

[17] A resist underlayer film for EB or EUV lithography, which is a fired product of a coating film of the composition for forming a resist underlayer film for EB or EUV lithography according to any one of [9] to

[16] .

[18] A semiconductor substrate; a resist underlayer film for EB or EUV lithography according to any one of [1] to [8] or

[17] ; A semiconductor processing substrate comprising:

[19] A step of forming a resist underlayer film having a thickness of less than 10 nm on a semiconductor substrate using the composition for forming a resist underlayer film for EB or EUV lithography according to any one of [9] to

[16] ; forming a resist film on the resist underlayer film using a resist for EB or EUV lithography; A method for manufacturing a semiconductor device, comprising:

[20] A step of forming a resist underlayer film having a thickness of less than 10 nm on a semiconductor substrate using the composition for forming a resist underlayer film for EB or EUV lithography according to any one of [9] to

[16] ; forming a resist film on the resist underlayer film using a resist for EB or EUV lithography; irradiating the resist film with EB or EUV, and then developing the resist film to obtain a resist pattern; etching the resist underlayer film using the resist pattern as a mask; A pattern forming method comprising:

[21] A step of forming a resist underlayer film having a thickness of less than 10 nm on a semiconductor substrate using the composition for forming a resist underlayer film for EB or EUV lithography according to any one of [9] to

[16] ; forming a resist film on the resist underlayer film using a resist for EB or EUV lithography; irradiating the resist film with EB or EUV, and then developing the resist film to obtain a resist pattern; A method for improving LWR of a resist pattern, comprising: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a resist underlayer film, a composition for forming a resist underlayer film for EB or EUV lithography, a resist underlayer film for EB or EUV lithography, a substrate for semiconductor processing, a method for manufacturing a semiconductor element, a pattern formation method, and a method for improving LWR of a resist pattern, which are capable of improving LWR of a resist pattern. DETAILED DESCRIPTION OF THE INVENTION

[0009] The resist underlayer film of the present invention is a fired product of a coating film of a composition for forming a resist underlayer film. Therefore, the resist underlayer film of the present invention will be described after explaining the composition for forming a resist underlayer film.

[0010] (Composition for forming resist underlayer film) The composition for forming a resist underlayer film of this embodiment contains a polymer having at least one unit structure selected from the group consisting of a unit structure (A) having a polycyclic aromatic hydrocarbon structure and a unit structure (B) derived from a maleimide structure. In addition to the polymer, the composition for forming a resist underlayer film of this embodiment may further contain a solvent, a crosslinking agent, and a curing catalyst. Other additives may also be added as long as they do not impair the effects of the present invention.

[0011] <Polymer> As described above, the polymer has at least one unit structure selected from the unit structure (A) having a polycyclic aromatic hydrocarbon structure and the unit structure (B) derived from a maleimide structure. When the polymer contains at least one of the unit structures (A) and (B) derived from a maleimide structure, adhesion between the resist and the resist underlayer film interface during resist pattern formation tends to be improved when used as a resist underlayer film. Therefore, it is presumed that peeling of the resist pattern does not occur and deterioration of LWR during resist pattern formation can be suppressed. This effect is particularly pronounced when using EUV (wavelength 13.5 nm) or EB (electron beam).

[0012] As used herein, the term "polycyclic aromatic hydrocarbon structure" refers to an aromatic structure having a polycyclic aromatic hydrocarbon. Furthermore, as used herein, the term "unit structure derived from a maleimide structure" refers to a repeating unit in a polymer obtained by reaction of a carbon-carbon double bond of maleimide or a maleimide derivative. The term "maleimide derivative" refers to a compound obtained by substituting the hydrogen atom of the NH group of maleimide.

[0013] <<Unit Structure (A)>> As described above, the unit structure (A) is a unit structure having a polycyclic aromatic hydrocarbon structure. In this specification, the term "polycyclic aromatic hydrocarbon structure" refers to an aromatic structure having hydrocarbons composed of two or more aromatic rings that exhibit aromaticity, and includes fused polycyclic aromatic hydrocarbon structures having fused rings, and hydrocarbon ring assembly structures in which multiple aromatic rings are directly bonded via single bonds. In this specification, the polycyclic aromatic hydrocarbon structure also includes a heterocyclic structure in which some carbon atoms in the aromatic ring are substituted with nitrogen.

[0014] The condensed polycyclic aromatic hydrocarbon structure is not particularly limited, but examples thereof include a naphthalene structure, an anthracene structure, a phenanthrene structure, a pyrene structure, a triphenylene structure, a chrysene structure, a naphthacene structure, a biphenylene structure, and a fluorene structure.

[0015] The hydrocarbon ring assembly structure is not particularly limited, but examples thereof include a carbazole structure, a biphenyl structure, a terphenyl structure, a quaterphenyl structure, a binaphthalene structure, a phenylnaphthalene structure, a phenylfluorene structure, and a diphenylfluorene structure.

[0016] The polycyclic aromatic hydrocarbon structure may be substituted with a substituent. The optionally substituted substituent is not particularly limited, and examples thereof include alkyl groups, hydroxy groups, carboxyl groups, and halogen groups (e.g., fluorine groups, chlorine groups, bromine groups, and iodine groups). Examples of the alkyl groups include methyl groups, ethyl groups, n-propyl groups, i-propyl groups, n-butyl groups, i-butyl groups, s-butyl groups, t-butyl groups, n-pentyl groups, 1-methyl-n-butyl groups, 2-methyl-n-butyl groups, 3-methyl-n-butyl groups, 1,1-dimethyl-n-propyl groups, 1,2-dimethyl-n-propyl groups, 2,2-dimethyl-n-propyl groups, 1-ethyl-n-propyl groups, n-hexyl groups, 1-methyl-n-pentyl groups, 2-methyl-n-pentyl groups, 3-methyl-n-pentyl groups, and the like. Examples of the alkyl group include a methyl group, a 4-methyl-n-pentyl group, a 1,1-dimethyl-n-butyl group, a 1,2-dimethyl-n-butyl group, a 1,3-dimethyl-n-butyl group, a 2,2-dimethyl-n-butyl group, a 2,3-dimethyl-n-butyl group, a 3,3-dimethyl-n-butyl group, a 1-ethyl-n-butyl group, a 2-ethyl-n-butyl group, a 1,1,2-trimethyl-n-propyl group, a 1,2,2-trimethyl-n-propyl group, a 1-ethyl-1-methyl-n-propyl group, and a 1-ethyl-2-methyl-n-propyl group.Furthermore, a cyclic alkyl group can also be used as the alkyl group. For example, examples of the cyclic alkyl group having 1 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a 1-methylcyclopropyl group, a 2-methylcyclopropyl group, a cyclopentyl group, a 1-methylcyclobutyl group, a 2-methylcyclobutyl group, a 3-methylcyclobutyl group, a 1,2-dimethylcyclopropyl group, a 2,3-dimethylcyclopropyl group, a 1-ethylcyclopropyl group, a 2-ethylcyclopropyl group, a cyclohexyl group, a 1-methylcyclopentyl group, a 2-methylcyclopentyl group, a 3-methylcyclopentyl group, a 1-ethylcyclobutyl group, a 2-ethylcyclobutyl group, a 3-ethylcyclobutyl group, a 1,2-dimethylcyclopropyl group, a cyclohexyl group, a 1-methylcyclopentyl group, a 2-methylcyclopentyl group, a 3-methylcyclopentyl group, a 1-ethylcyclobutyl group, a 2-ethylcyclobutyl group, a 3-ethylcyclobutyl group, a 1,2-dimethylcyclopropyl group, a cyclohexyl group, a cyclopent ... Examples of such groups include 1-n-propylcyclobutyl group, 1,3-dimethylcyclobutyl group, 2,2-dimethylcyclobutyl group, 2,3-dimethylcyclobutyl group, 2,4-dimethylcyclobutyl group, 3,3-dimethylcyclobutyl group, 1-n-propylcyclopropyl group, 2-n-propylcyclopropyl group, 1-i-propylcyclopropyl group, 2-i-propylcyclopropyl group, 1,2,2-trimethylcyclopropyl group, 1,2,3-trimethylcyclopropyl group, 2,2,3-trimethylcyclopropyl group, 1-ethyl-2-methylcyclopropyl group, 2-ethyl-1-methylcyclopropyl group, 2-ethyl-2-methylcyclopropyl group, and 2-ethyl-3-methylcyclopropyl group.

[0017] From the viewpoint of suitably obtaining the effects of the present invention, the polycyclic aromatic hydrocarbon structure is preferably a naphthalene structure, an anthracene structure, a phenanthrene structure, a pyrene structure, a triphenylene structure, a chrysene structure, a naphthacene structure, a biphenylene structure, a fluorene structure, or a carbazole structure, more preferably a naphthalene structure, an anthracene structure, a phenanthrene structure, a pyrene structure, or a carbazole structure, and even more preferably a naphthalene structure or a carbazole structure. The polycyclic aromatic hydrocarbon structure may be of one type or two or more types, but is preferably of one or two types.

[0018] The unit structure (A) is not particularly limited, but a unit structure represented by the following formula (1) can be suitably used. [ka] (In formula (1), R 1 represents a hydrogen atom or a methyl group. X represents an ester group or an amide group. Y represents an alkylene group having 1 to 6 carbon atoms. p and q each independently represent 0 or 1. Ar represents a monovalent group obtained by removing a hydrogen atom from naphthalene, anthracene, phenanthrene, pyrene, triphenylene, chrysene, naphthacene, biphenylene, fluorene, or carbazole, which may be substituted.

[0019] Furthermore, the unit structure (A) is not particularly limited, but a unit structure represented by the following formula (2) can be suitably used. [ka] (In formula (2), R 1 represents a hydrogen atom or a methyl group, Z represents a halogen atom, a hydroxyl group, an alkyl group, an alkoxy group, a thiol group, a cyano group, a carboxyl group, an amino group, an amido group, an alkoxycarbonyl group, or a thioalkyl group substituted on a naphthalene ring, and n represents an integer of 0 to 7. When n is 2 or more, two or more Zs may be the same or different.

[0020] In Z, the halogen atom can be a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. The alkyl group can be, for example, a linear or branched alkyl group having 1 to 6 carbon atoms, which may be substituted with a halogen atom or the like. Examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butoxy group, a t-butoxy group, an n-hexyl group, and a chloromethyl group. Examples of the alkoxy group can be, for example, an alkoxy group having 1 to 6 carbon atoms, such as a methoxy group, an ethoxy group, and an isopropoxy group. Examples of the amide group can be, for example, an amide group having 1 to 12 carbon atoms, such as a formamide group, an acetamide group, a propionamide group, an isobutylamide group, a benzamide group, a naphthylamide group, and an acrylamide group. Examples of the alkoxycarbonyl group can be, for example, an alkoxycarbonyl group having 1 to 12 carbon atoms, such as a methoxycarbonyl group, an ethoxycarbonyl group, and a benzyloxycarbonyl group. The thioalkyl group is, for example, a thioalkyl group having 1 to 6 carbon atoms, such as a methylthio group, an ethylthio group, a butylthio group, and a hexylthio group.

[0021] Specific examples of the unit structure (A) represented by formula (2) include the following. [ka] [ka]

[0022] Furthermore, the unit structure (A) is not particularly limited, but a unit structure represented by the following formula (3) can be suitably used. [ka] (In formula (3), Ar 1 and Ar 2 each independently represents an aromatic ring having 6 to 40 carbon atoms which may be substituted, and Ar 1 and Ar 2At least one of is naphthalene, anthracene, phenanthrene, or pyrene, and Q represents a single bond or a divalent linking group.

[0023] Examples of aromatic rings having 6 to 40 carbon atoms include benzene, naphthalene, anthracene, acenaphthene, fluorene, triphenylene, phenalene, phenanthrene, indene, indane, indacene, pyrene, chrysene, perylene, naphthacene, pentacene, coronene, heptacene, benzo[a]anthracene, dibenzophenanthrene, and dibenzo[a,j]anthracene.

[0024] Examples of the divalent linking group for Q include an ether group, an ester group, and an imino group, and an imino group is preferred.

[0025] The unit structure (A) may be of one or more types, preferably one or two types.

[0026] When the polymer contains the unit structure (A), the molar ratio of the unit structure (A) is preferably 10 to 90 mol %, more preferably 30 to 85 mol %, and even more preferably 40 to 80 mol %, based on the total unit structures of the polymer, from the viewpoint of suitably achieving the effects of the present invention.

[0027] <<Unit Structure (B)>> The unit structure (B) is the above-mentioned unit structure derived from a maleimide structure.

[0028] The unit structure (B) is preferably a unit structure represented by the following formula (4). [ka] (In formula (4), R 2 represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be substituted with a hydroxy group, or an aryl group having 6 to 10 carbon atoms which may be substituted with a halogen atom.

[0029] The alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. Examples of the alkylene group having 1 to 10 carbon atoms include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, a cyclopropylene group, an n-butylene group, an isobutylene group, an s-butylene group, a t-butylene group, a cyclobutylene group, a 1-methylcyclopropylene group, a 2-methylcyclopropylene group, an n-pentylene group, a 1-methyl-n-butylene group, a 2-methyl-n-butylene group, a 3-methyl-n-butylene group, a 1,1-dimethyl-n-propylene group, a 1,2-dimethyl-n-propylene group, a 2 ... propylene, 1-ethyl-n-propylene, cyclopentylene, 1-methyl-cyclobutylene, 2-methyl-cyclobutylene, 3-methyl-cyclobutylene, 1,2-dimethyl-cyclopropylene, 2,3-dimethyl-cyclopropylene, 1-ethyl-cyclopropylene, 2-ethyl-cyclopropylene, n-hexylene, 1-methyl-n-pentylene, 2-methyl-n-pentylene, 3-methyl-n-pentylene, 4-methyl-n-pentylene, 1,1-dimethyl-n-butylene, 1,2-dimethyl- n-butylene group, 1,3-dimethyl-n-butylene group, 2,2-dimethyl-n-butylene group, 2,3-dimethyl-n-butylene group, 3,3-dimethyl-n-butylene group, 1-ethyl-n-butylene group, 2-ethyl-n-butylene group, 1,1,2-trimethyl-n-propylene group, 1,2,2-trimethyl-n-propylene group, 1-ethyl-1-methyl-n-propylene group, 1-ethyl-2-methyl-n-propylene group, cyclohexylene group, 1-methyl-cyclopentylene group, 2-methyl-cyclopentylene group, 3-methyl-cyclo Pentylene group, 1-ethyl-cyclobutylene group, 2-ethyl-cyclobutylene group, 3-ethyl-cyclobutylene group, 1,2-dimethyl-cyclobutylene group, 1,3-dimethyl-cyclobutylene group, 2,2-dimethyl-cyclobutylene group, 2,3-dimethyl-cyclobutylene group, 2,4-dimethyl-cyclobutylene group, 3,3-dimethyl-cyclobutylene group, 1-n-propyl-cyclopropylene group, 2-n-propyl-cyclopropylene group, 1-isopropyl-cyclopropylene group, 2-isopropyl-cyclopropylene group, 1,2,Examples of the cyclopropylene group include a 2-trimethyl-cyclopropylene group, a 1,2,3-trimethyl-cyclopropylene group, a 2,2,3-trimethyl-cyclopropylene group, a 1-ethyl-2-methyl-cyclopropylene group, a 2-ethyl-1-methyl-cyclopropylene group, a 2-ethyl-2-methyl-cyclopropylene group, a 2-ethyl-3-methyl-cyclopropylene group, an n-heptylene group, an n-octylene group, an n-nonylene group, and an n-decanylene group. Any hydrogen atom in these alkyl groups having 1 to 10 carbon atoms may be substituted with a hydroxy group.

[0030] The halogen atoms are as described above. Examples of the aryl group having 6 to 10 carbon atoms include a phenyl group, a benzyl group, and a naphthyl group.

[0031] Specific examples of the unit structure (B) represented by formula (4) include the following unit structures. [ka]

[0032] The unit structure (B) may be of one or more types, preferably one or two types.

[0033] When the polymer contains the unit structure (B), the molar ratio of the unit structure (B) is preferably 10 to 90 mol %, more preferably 10 to 75 mol %, and even more preferably 10 to 50 mol %, based on the total unit structures of the polymer, from the viewpoint of suitably achieving the effects of the present invention.

[0034] When the polymer contains the unit structure (A) and the unit structure (B), the total molar ratio of the unit structure (A) and the unit structure (B) is preferably 20 mol % or more, more preferably 40 mol % or more, and even more preferably 50 mol % or more, based on all the unit structures of the polymer, from the viewpoint of suitably obtaining the effects of the present invention.

[0035] <<Unit Structure (C)>> The polymer of the present embodiment may optionally further contain a unit structure (C) having a crosslinking group in addition to the unit structure (A) and / or the unit structure (B). The crosslinking group can undergo a crosslinking reaction with a crosslinking agent component optionally incorporated into the composition for forming a resist underlayer film of the present invention upon heating and baking. The resist underlayer film formed by such a crosslinking reaction has the effect of preventing intermixing with the resist film coated thereon.

[0036] The cross-linking group is not particularly limited as long as it is a group that forms a chemical bond between molecules, and may be, for example, a hydroxy group, an epoxy group, a protected hydroxy group, or a protected carboxyl group. There may be any number of cross-linking groups in one molecule.

[0037] Examples of the hydroxy group include a hydroxy group derived from a hydroxyalkyl (meth)acrylate, vinyl alcohol, or the like, and a phenolic hydroxy group derived from a hydroxystyrene, or the like. Examples of the alkyl group include the alkyl groups described above, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. In this specification, the term "(meth)acrylate" refers to both methacrylate and acrylate.

[0038] Examples of the epoxy group include epoxy groups derived from epoxy (meth)acrylate, glycidyl (meth)acrylate, and the like.

[0039] Examples of protected hydroxy groups include hydroxystyrenes in which the hydroxy group is protected with a tert-butoxy group. Other examples include hydroxy groups protected by reacting a phenolic hydroxy group, such as hydroxystyrene, with a vinyl ether compound, and hydroxy groups protected by reacting an alcoholic hydroxy group, such as hydroxyethyl methacrylate, with a vinyl ether compound. Examples of vinyl ether compounds include aliphatic vinyl ether compounds having a vinyl ether group and an alkyl chain having 1 to 10 carbon atoms, such as methyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, 2-ethylhexyl vinyl ether, tert-butyl vinyl ether, and cyclohexyl vinyl ether, as well as cyclic vinyl ether compounds such as 2,3-dihydrofuran, 4-methyl-2,3-dihydrofuran, and 2,3-dihydro-4H-pyran.

[0040] Examples of the protected carboxyl group include a carboxyl group protected by reacting a vinyl ether compound with the carboxyl group of (meth)acrylic acid or vinylbenzoic acid. Examples of the vinyl ether compound used here include the above-mentioned vinyl ether compounds.

[0041] Examples of the crosslinking group include an amino group, an isocyanate group, a protected amino group, and a protected isocyanate group. The amino group must have at least one active hydrogen, but an amino group in which one active hydrogen of the amino group is substituted with an alkyl group or the like can also be used. The alkyl group can be the alkyl group described above.

[0042] The protected amino group is one in which at least one hydrogen atom of the amino group is protected with an alkoxycarbonyl group such as a t-butoxycarbonyl group or a 9-fluorenylmethoxycarbonyl group.

[0043] The protected isocyanate group is obtained by reacting an isocyanate group with a protecting agent. The protecting agent is an active hydrogen-containing compound capable of reacting with isocyanate, such as alcohol, phenol, polycyclic phenol, amide, imide, imine, thiol, oxime, lactam, active hydrogen-containing heterocycle, or active methylene-containing compound.

[0044] Examples of the alcohol as a protecting agent include alcohols having 1 to 40 carbon atoms, such as methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, octanol, ethylene chlorohydrin, 1,3-dichloro-2-propanol, t-butanol, t-pentanol, 2-ethylhexanol, cyclohexanol, lauryl alcohol, ethylene glycol, butylene glycol, trimethylolpropane, glycerin, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and benzyl alcohol.

[0045] Examples of the phenol as a protecting agent include phenols having 6 to 20 carbon atoms, such as phenol, chlorophenol, and nitrophenol. Examples of the phenol derivatives used as the protecting agent include phenol derivatives having 6 to 20 carbon atoms, such as para-t-butylphenol, cresol, xylenol, and resorcinol. Examples of polycyclic phenols as protecting agents include polycyclic phenols having 10 to 20 carbon atoms, which are aromatic condensed rings having a phenolic hydroxy group, and examples thereof include hydroxynaphthalene and hydroxyanthracene.

[0046] The amide as the protecting agent may be, for example, an amide having 1 to 20 carbon atoms, such as acetanilide, hexanamide, octanediamide, succinamide, benzenesulfonamide, or ethanediamide. The imide as the protecting agent may be, for example, an imide having 6 to 20 carbon atoms, such as cyclohexanedicarboximide, cyclohexaenedicarboximide, benzenedicarboximide, cyclobutanedicarboximide, or carbodiimide. The imine as the protecting agent is, for example, an imine having 1 to 20 carbon atoms, such as hexane-1-imine, 2-propaneimine, and ethane-1,2-imine.

[0047] The thiol as the protecting agent may be, for example, a thiol having 1 to 20 carbon atoms, such as ethanethiol, butanethiol, thiophenol, and 2,3-butanedithiol. The oxime as a protecting agent is, for example, an oxime having 1 to 20 carbon atoms, and examples thereof include acetoxime, methyl ethyl ketoxime, cyclohexanone oxime, dimethyl ketoxime, methyl isobutyl ketoxime, methyl amyl ketoxime, formamide oxime, acetaldoxime, diacetyl monooxime, benzophenone oxime, and cyclohexane oxime. The lactam as a protecting agent is, for example, a lactam having 4 to 20 carbon atoms, and examples thereof include ε-caprolactam, δ-valerolactam, γ-butyrolactam, β-propyllactam, γ-pyrrolidone, and lauryllactam.

[0048] The active hydrogen-containing heterocyclic compound as a protecting agent is, for example, an active hydrogen-containing heterocyclic compound having 3 to 30 carbon atoms, and examples thereof include pyrrole, imidazole, pyrazole, piperidine, piperazine, morpholine, pyridine, indole, indazole, purine, and carbazole. The active methylene-containing compound as a protecting agent is, for example, an active methylene-containing compound having 3 to 20 carbon atoms, and examples thereof include dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, and acetylacetone.

[0049] The crosslinking group is not particularly limited, but a hydroxy group can be preferably used. As the unit structure (C) having such a crosslinking group, a unit structure derived from the above-mentioned hydroxyalkyl (meth)acrylate is preferred, and a unit structure derived from hydroxyethyl (meth)acrylate is particularly more preferred. The term "unit structure derived from a hydroxyalkyl (meth)acrylate" refers to a repeating unit in a polymer that is obtained by reaction of the carbon-carbon double bond of a hydroxyalkyl (meth)acrylate.

[0050] When the polymer contains the unit structure (C), the molar ratio of the unit structure (C) is preferably 5 to 90 mol %, more preferably 10 to 80 mol %, and even more preferably 15 to 75 mol %, based on the total unit structures of the polymer, from the viewpoint of suitably achieving the effects of the present invention.

[0051] <<Polymer characteristics>> The distribution of the unit structures represented by unit structures (A), (B), and (C) in the polymer is not particularly limited. The polymer may be a homopolymer of unit structure (A) or a homopolymer of unit structure (B), but preferably has at least unit structure (A). When the polymer is a copolymer of unit structure (A) and unit structure (B), unit structure (A) and unit structure (B) may be alternately copolymerized or randomly copolymerized. Furthermore, when unit structure (C) coexists, the unit structures in the polymer may each constitute a block or may be randomly bonded.

[0052] The molecular weight of the polymer is not particularly limited, but the weight average molecular weight determined by gel permeation chromatography (hereinafter sometimes abbreviated as GPC) is preferably 1,500 to 100,000, and more preferably 2,000 to 50,000.

[0053] <<Polymer manufacturing method>> The method for producing the polymer is not particularly limited, and for example, the polymer of the present embodiment can be obtained by reacting a carbon-carbon double bond in a monomer of unit structure (A), a carbon-carbon double bond in a monomer of unit structure (B), and a carbon-carbon double bond in an arbitrary monomer of unit structure (C).

[0054] As a polymerizing method, known polymerization methods such as radical polymerization, anionic polymerization, cationic polymerization, etc., and various known techniques such as solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization can be used.

[0055] The polymerization initiator used in the polymerization is not particularly limited, but examples thereof include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2 ,2'-Azobis(isobutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 1-[(1-cyano-1-methylethyl)azo]formamide, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], and 2,2'-azobis(2-methylpropionamidine) dihydrochloride, etc. are used.

[0056] The solvent used during polymerization is not particularly limited, and examples thereof include dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl 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-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, and butyl lactate. These may be used alone or in combination.

[0057] The reaction temperature is not particularly limited, but may be, for example, 20°C to 160°C. The reaction time is not particularly limited, but may be, for example, 1 hour to 72 hours.

[0058] The resulting solution containing the polymer can be used as is for preparing a composition for forming a resist underlayer film, or the polymer can be recovered by precipitation and isolation in a poor solvent such as methanol, ethanol, isopropanol, or water, or a mixed solvent thereof, and then used.

[0059] The content of the polymer in the composition for forming a resist underlayer film is not particularly limited, but from the viewpoint of solubility, it is preferably 0.1% by mass to 50% by mass, and more preferably 0.1% by mass to 10% by mass, based on the entire composition for forming a resist underlayer film.

[0060] <Crosslinking agent> The crosslinking agent contained as an optional component in the composition for forming a resist underlayer film may be a nitrogen-containing compound having, per molecule, 2 to 6 substituents bonded to nitrogen atoms and represented by the following formula (1d), as described in WO 2017 / 187969:

[0061] [ka] (In formula (1d), R1 represents a methyl group or an ethyl group. * represents a bond bonded to the nitrogen atom.)

[0062] The nitrogen-containing compound having 2 to 6 substituents represented by the above formula (1d) in one molecule may be a glycoluril derivative represented by the following formula (1E).

[0063] [ka] (In formula (1E), four R1s each independently represent a methyl group or an ethyl group, and R2 and R3 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group.)

[0064] Examples of the glycoluril derivative represented by the above formula (1E) include compounds represented by the following formulae (1E-1) to (1E-6).

[0065] [ka]

[0066] The nitrogen-containing compound having 2 to 6 substituents represented by the above formula (1d) in one molecule can be obtained by reacting a nitrogen-containing compound having 2 to 6 substituents bonded to a nitrogen atom in one molecule represented by the following formula (2d) with at least one compound represented by the following formula (3d):

[0067] [ka] (In formula (2d) and formula (3d), R1 represents a methyl group or an ethyl group, and R4 represents an alkyl group having 1 to 4 carbon atoms. * represents a bond bonded to the nitrogen atom.)

[0068] The glycoluril derivative represented by the above formula (1E) can be obtained by reacting a glycoluril derivative represented by the following formula (2E) with at least one compound represented by the above formula (3d).

[0069] The nitrogen-containing compound having 2 to 6 substituents represented by the above formula (2d) in one molecule is, for example, a glycoluril derivative represented by the following formula (2E).

[0070] [ka] (In formula (2E), R2 and R3 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group, and R4 each independently represent an alkyl group having 1 to 4 carbon atoms.)

[0071] Examples of glycoluril derivatives represented by the above formula (2E) include compounds represented by the following formulae (2E-1) to (2E-4): Furthermore, examples of compounds represented by the above formula (3d) include compounds represented by the following formulae (3d-1) and (3d-2):

[0072] [ka] [ka]

[0073] The entire disclosure of WO2017 / 187969 is incorporated herein by reference with respect to the content of the nitrogen-containing compound having 2 to 6 substituents represented by formula (1d) bonded to the nitrogen atom in one molecule.

[0074] The crosslinking agent may also be a compound represented by the following formula (21): [ka] (In formula (21), R 1 each independently represents an alkylene group having 1 to 6 carbon atoms; R 2 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxyalkyl group having a total of 2 to 10 carbon atoms; R 3 each independently represents an alkyl group having 1 to 6 carbon atoms; m1 and m2 each independently represents an integer of 1 or 2; when m1 and m2 are 1, Q 1 represents a single bond, an oxygen atom, or a divalent organic group having 1 to 20 carbon atoms; otherwise, Q 1 represents an organic group having 1 to 20 carbon atoms and a valence of (m1+m2).

[0075] Q 1 In the above formula, examples of the (m1+m2)-valent organic group having 1 to 20 carbon atoms include groups represented by any of the following formulas (21-1) to (21-5).

[0076] [ka] (In formula (21-1), Ra and Rb each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a —CF 3 group. In formula (21-3), X represents a trivalent group having 1 to 30 carbon atoms. In formula (21-4), Ar represents a divalent aromatic hydrocarbon group. * represents a bond.)

[0077] Ar represents, for example, a divalent residue of a compound selected from benzene, biphenyl, naphthalene, and anthracene.

[0078] The group represented by formula (21-1) is a divalent group. The group represented by formula (21-2) is a tetravalent group. The group represented by formula (21-3) is a trivalent group. The group represented by formula (21-4) is a divalent group. The group represented by formula (21-5) is a trivalent group.

[0079] When the above-mentioned crosslinking agent is used, the content of the crosslinking agent is, for example, 1% by mass to 50% by mass, and preferably 5% by mass to 30% by mass, relative to the polymer having at least one of the unit structures (A) and (B).

[0080] <<Curing catalyst>> The curing catalyst contained as an optional component in the composition for forming a resist underlayer film may be either a thermal acid generator or a photoacid generator, but it is preferable to use a thermal acid generator.

[0081] Examples of the thermal acid generator include sulfonic acid compounds and carboxylic acid compounds such as p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium-p-toluenesulfonate (pyridinium-p-toluenesulfonic acid), pyridinium phenolsulfonic acid, pyridinium-p-hydroxybenzenesulfonic acid (pyridinium p-phenolsulfonate salt), pyridinium-trifluoromethanesulfonic acid, salicylic acid, camphorsulfonic acid, 5-sulfosalicylic acid, 4-chlorobenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, citric acid, benzoic acid, and hydroxybenzoic acid.

[0082] Examples of the photoacid generator include an onium salt compound, a sulfonimide compound, and a disulfonyldiazomethane compound.

[0083] Examples of the onium salt compound include iodonium salt compounds such as diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-normal butanesulfonate, diphenyliodonium perfluoro-normal octanesulfonate, diphenyliodonium camphorsulfonate, bis(4-tert-butylphenyl)iodonium camphorsulfonate, and bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate; and sulfonium salt compounds such as triphenylsulfonium hexafluoroantimonate, triphenylsulfonium nonafluoro-normal butanesulfonate, triphenylsulfonium camphorsulfonate, and triphenylsulfonium trifluoromethanesulfonate.

[0084] Examples of the sulfonimide compound include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoronormalbutanesulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, and N-(trifluoromethanesulfonyloxy)naphthalimide.

[0085] Examples of 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.

[0086] The curing catalyst may be used alone or in combination of two or more.

[0087] When a curing catalyst is used, the content of the curing catalyst is, for example, 0.1% by mass to 50% by mass, and preferably 1% by mass to 30% by mass, relative to the crosslinking agent.

[0088] <<Other ingredients>> A surfactant may be further added to the composition for forming a resist underlayer film in order to prevent pinholes, striations, etc., and to further improve coating properties for preventing surface irregularities.

[0089] Examples of surfactants 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 monolaurate; polyoxyethylene sorbitan monopalmitate; nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters, such as polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate; fluorine-based surfactants such as F-TOP EF301, EF303, and EF352 (trade names, manufactured by Tochem Products Co., Ltd.), Megafac F171, F173, and R-30 (trade names, manufactured by DIC Corporation), Fluorad FC430 and FC431 (trade names, manufactured by Sumitomo 3M Limited), Asahiguard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (trade names, manufactured by Asahi Glass Co., Ltd.); and organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.). The amount of these surfactants to be added is not particularly limited, but is usually 2.0% by mass or less, and preferably 1.0% by mass or less, based on the composition for forming a resist underlayer film. These surfactants may be added alone or in combination of two or more.

[0090] <Solvent> The solvent is preferably an organic solvent generally used in chemical solutions for semiconductor lithography processes, specifically ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, cyclohexane, cyclohexane-1, cyclohexane-2, cyclohexane-3, cyclohexane-4, cyclohexane-5, cyclohexane-6, cyclohexane-7, cyclohexane-8, cyclohexane-9, cyclohexane-10, cyclohexane-11, cyclohexane-12, cyclohexane-13, cyclohexane-14, cyclohexane-15, cyclohexane-16, cyclohexane-17, cyclohexane-18, cyclohexane-19, cyclohexane-20, cyclohexane-21, cyclohexane-22, cyclohexane-23, cyclohexane-24, cyclohexane-25, cyclohexane-26, cyclohexane-27, cyclohexane-28, cyclohexane-29, cyclohexane-30, cyclohexane-31, cyclohexane-32, cyclohexane-33, cyclohexane-34, cyclohexane-35, cyclohexane-36, cyclohexane-37, cyclohexane-38, cyclohexane-39, cyclohexane-40, cyclohexane-41, cyclohexane-42, cyclohexane-43, cyclohexane-44, cyclohexane-45, cyclohexane-45, cyclohexane-46, cyclohexane-47, cyclohexane-48, cyclohexane-49, cyclohexane-51, cyclohexane-52, cyclohexane-53, cyclohexane-54 Examples of suitable solvents include heptanone, 4-methyl-2-pentanol, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, ethyl ethoxyacetate, 2-hydroxyethyl acetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, 2-heptanone, methoxycyclopentane, anisole, γ-butyrolactone, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. These solvents may be used alone or in combination of two or more.

[0091] Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl lactate, and cyclohexanone are preferred, with propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate being particularly preferred.

[0092] The composition for forming a resist underlayer film is preferably used as a composition for forming a resist underlayer film for EB or EUV lithography. The composition for forming a resist underlayer film for EB or EUV lithography is preferably used to form a resist underlayer film for EB or EUV lithography having a film thickness of less than 10 nm.

[0093] (resist underlayer film) The resist underlayer film of the present invention is a fired product of a coating film of the above-mentioned composition for forming a resist underlayer film.

[0094] The thickness of the resist underlayer film of the present invention is less than 10 nm. Usually, when the thickness of the resist underlayer film is reduced, it becomes difficult to obtain a film with a flat surface. If the surface is not flat, the thickness of the resist layer formed on the underlayer film will vary greatly, resulting in a large LWR. The resist underlayer film of the present invention contains the above-mentioned polymer, and therefore tends to have excellent adhesion to the substrate and excellent film-forming properties. Therefore, even if the resist underlayer film has a thickness of less than 10 nm, it is possible to form a film with a flat surface, and it is presumed that the LWR of the resist pattern can be improved. This effect is particularly pronounced when EUV or EB is used.

[0095] If a resist underlayer film with a thickness of 20 nm or more is used when EUV or EB is used, the resist film is thin, so in the dry etching process after resist pattern formation, the resist pattern is damaged during the etching of the underlayer film, resulting in shape defects such as a reduction in resist film thickness and top-rounding, making it difficult to form a pattern with the desired line width during actual substrate processing.

[0096] The resist underlayer film of the present invention can be produced by applying a composition for forming a resist underlayer film onto a semiconductor substrate and baking the applied composition.

[0097] Examples of semiconductor substrates to which the composition for forming a resist underlayer film of the present invention can be applied include silicon wafers, germanium wafers, and wafers of compound semiconductors such as gallium arsenide, indium phosphide, gallium nitride, indium nitride, and aluminum nitride.

[0098] When a semiconductor substrate having an inorganic film formed on its surface is used, the inorganic film can be formed by, for example, ALD (atomic layer deposition), CVD (chemical vapor deposition), reactive sputtering, ion plating, vacuum deposition, or spin-coating (spin-on-glass: SOG). Examples of the inorganic film include polysilicon film, silicon oxide film, silicon nitride film, BPSG (Boro-Phospho Silicate Glass) film, titanium nitride film, titanium nitride oxide film, tungsten film, gallium nitride film, and gallium arsenide film.

[0099] The resist underlayer film-forming composition of the present invention is applied onto such a semiconductor substrate using an appropriate application method such as a spinner or coater. The composition is then baked using a heating means such as a hot plate to form a resist underlayer film. Baking conditions are appropriately selected from a baking temperature of 100°C to 400°C and a baking time of 0.3 to 60 minutes. A baking temperature of 120°C to 350°C and a baking time of 0.5 to 30 minutes are preferred, and a baking temperature of 150°C to 300°C and a baking time of 0.8 to 10 minutes are more preferred.

[0100] The thickness of the resist underlayer film is less than 10 nm, preferably 9 nm or less, more preferably 8 nm or less, and even more preferably 7 nm or less, and may be 1 nm or more, 2 nm or more, or 3 nm or more.

[0101] In this specification, the method for measuring the film thickness of the resist underlayer film is as follows. Measurement equipment name: Ellipsometric film thickness measurement equipment RE-3100 (SCREEN Co., Ltd.) SWE (Single Wavelength Ellipsometer) mode Arithmetic mean of 8 points (e.g., 8 points measured at 1cm intervals in the X direction of the wafer)

[0102] The resist underlayer film is preferably used as a resist underlayer film for EB or EUV lithography.

[0103] (Substrates for semiconductor processing) The substrate for semiconductor processing of the present invention comprises a semiconductor substrate and the resist underlayer film or the resist underlayer film for EB or EUV lithography of the present invention. The semiconductor substrate may be, for example, the semiconductor substrate described above. The resist underlayer film or the resist underlayer film for EB or EUV lithography is disposed, for example, on a semiconductor substrate.

[0104] (Semiconductor element manufacturing method, pattern formation method, and method for improving LWR of resist pattern) The method for manufacturing a semiconductor device of the present invention includes at least the following steps. forming a resist underlayer film having a thickness of less than 10 nm on a semiconductor substrate using the composition for forming a resist underlayer film for EB or EUV lithography of the present invention; and A process of forming a resist film on the resist underlayer film using a resist for EB or EUV lithography.

[0105] The pattern forming method of the present invention includes at least the following steps. forming a resist underlayer film having a thickness of less than 10 nm on a semiconductor substrate using the composition for forming a resist underlayer film for EB or EUV lithography of the present invention; A process of forming a resist film on the resist underlayer film using a resist for EB or EUV lithography. A step of irradiating the resist film with EB or EUV and then developing the resist film to obtain a resist pattern; and A process of etching the resist underlayer film using the resist pattern as a mask.

[0106] The method for improving LWR of a resist pattern of the present invention includes at least the following steps. forming a resist underlayer film having a thickness of less than 10 nm on a semiconductor substrate using the composition for forming a resist underlayer film for EB or EUV lithography of the present invention; forming a resist film on the resist underlayer film using a resist for EB or EUV lithography; A step of irradiating the resist film with EB or EUV and then developing the resist film to obtain a resist pattern; In the method for improving the LWR of a resist pattern, the resist underlayer film obtained from the composition for forming a resist underlayer film for EB or EUV lithography of the present invention is used under a resist film, thereby making it possible to improve the non-uniformity of the resist pattern width (LWR: Line width roughness) in EB or EUV lithography.

[0107] Usually, a resist film is formed on a resist underlayer film. The thickness of the resist film is not particularly limited, but is preferably 200 nm or less, more preferably 150 nm or less, even more preferably 100 nm or less, and particularly preferably 80 nm or less. The thickness of the resist film is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more.

[0108] The resist formed by coating and baking on the resist underlayer film by a known method is not particularly limited as long as it responds to the EB or EUV used for irradiation. Either a negative photoresist or a positive photoresist can be used. In this specification, a resist that responds to EB is also referred to as a photoresist. Examples of photoresists include positive photoresists made of novolac resin and 1,2-naphthoquinone diazide sulfonic acid ester, chemically amplified photoresists made of a binder having a group that decomposes in the presence of acid to increase the alkaline dissolution rate and a photoacid generator, chemically amplified photoresists made of a low-molecular-weight compound that decomposes in the presence of acid to increase the alkaline dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator, and chemically amplified photoresists made of a binder having a group that decomposes in the presence of acid to increase the alkaline dissolution rate of the photoresist, a low-molecular-weight compound that decomposes in the presence of acid to increase the alkaline dissolution rate of the photoresist, and a photoacid generator, and resists containing metal elements. Examples include V146G (trade name) manufactured by JSR Corporation, APEX-E (trade name) manufactured by Shipley Chemical Co., Ltd., PAR710 (trade name) manufactured by Sumitomo Chemical Co., Ltd., and AR2772 and SEPR430 (trade names) manufactured by Shin-Etsu Chemical Co., Ltd. Further examples include fluorine-containing polymer photoresists such as those described in Proc. SPIE, Vol. 3999, 330-334 (2000), Proc. SPIE, Vol. 3999, 357-364 (2000), and Proc. SPIE, Vol. 3999, 365-374 (2000).

[0109] Also, WO2019 / 188595, WO2019 / 187881, WO2019 / 187803, WO2019 / 167737, WO2019 / 167725, WO2019 / 187445, WO2019 / 167419, WO2019 / 123842, WO2019 / 054282, WO2019 / 058945, WO2019 / 058890, WO2019 / 039290, WO2019 / 044259, WO2019 / 044231, WO2019 / 026549, WO2018 / 193954, WO2019 / 123842 9 / 172054, WO2019 / 021975, WO2018 / 230334, WO2018 / 194123, JP 2018-180525, WO2018 / 190088, JP 2018-070596, JP 2018-028090, JP 2016-153409, JP 2016-130240, JP 2016-108325, JP 2016-047920, JP 2016-035570, JP 2016-035567, JP 2016-035565, JP 2019-101417, JP 2019-117373, JP 2019-052294, JP 2019-008280, JP 2019-008279, JP 2019-003176, JP 2019-003175, JP 2018-197853, JP 2019-191298, JP 2019-061217, JP 2018-045152, JP 2018-022039, JP 2016-090441, JP 2015-10878, JP 2012-168279, JP 2012-022261, JP 2012-022258, JP 2011-043749, JP 2010-18 1857, JP 2010-128369, WO2018 / 031896, JP 2019-113855, WO2017 / 156388, WO2017 / 066319, JP 2018-41099, WO2016 / 065120, WO2015 / 026482, JP 2016-29498, JP 2011-253185, etc., radiation-sensitive resin compositions, so-called resist compositions such as high-resolution patterning compositions based on organometallic solutions, and metal-containing resist compositions can be used, but are not limited to these.

[0110] Examples of the resist composition include the following compositions.

[0111] An actinic ray-sensitive or radiation-sensitive resin composition comprising: resin A having a repeating unit having an acid-decomposable group in which a polar group is protected with a protecting group that is cleaved by the action of an acid; and a compound represented by the following general formula (21):

[0112] [ka] In the general formula (21), m represents an integer of 1 to 6. R1 and R2 each independently represent a fluorine atom or a perfluoroalkyl group. L1 represents -O-, -S-, -COO-, -SO2-, or -SO3-. L2 represents an alkylene group which may have a substituent or a single bond. W1 represents a cyclic organic group which may have a substituent. M + represents a cation.

[0113] A metal-containing film-forming composition for extreme ultraviolet or electron beam lithography, comprising a compound having a metal-oxygen covalent bond and a solvent, wherein the metal element constituting the compound belongs to Periods 3 to 7 of Groups 3 to 15 of the periodic table.

[0114] A radiation-sensitive resin composition comprising a polymer having a first structural unit represented by the following formula (31) and a second structural unit represented by the following formula (32) containing an acid-dissociable group, and an acid generator.

[0115] [ka] In formula (31), Ar is a group obtained by removing (n+1) hydrogen atoms from an arene having 6 to 20 carbon atoms. 1 is a hydroxy group, a sulfanyl group, or a monovalent organic group having 1 to 20 carbon atoms. n is an integer of 0 to 11. When n is 2 or more, multiple R 1 are the same or different. R 2is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 3 is a monovalent group having 1 to 20 carbon atoms containing the above acid-dissociable group. Z is a single bond, an oxygen atom, or a sulfur atom. R 4 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0116] A resist composition comprising: a resin (A1) containing a structural unit having a cyclic carbonate structure, a structural unit represented by the following formula, and a structural unit having an acid labile group; and an acid generator.

[0117] [ka] [In the formula, R 2 represents an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, a hydrogen atom or a halogen atom; X 1 is a single bond, -CO-O-* or -CO-NR 4 -*, * represents a bond to -Ar, R 4 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Ar represents an aromatic hydrocarbon group having 6 to 20 carbon atoms which may have one or more groups selected from the group consisting of a hydroxy group and a carboxyl group.]

[0118] Examples of the resist film include the following.

[0119] A resist film comprising a base resin containing a repeating unit represented by the following formula (a1) and / or a repeating unit represented by the following formula (a2), and a repeating unit that generates an acid bonded to the polymer main chain upon exposure:

[0120] [ka] (In formula (a1) and formula (a2), R A are each independently a hydrogen atom or a methyl group. 1 and R 2are each independently a tertiary alkyl group having 4 to 6 carbon atoms. 3 are each independently a fluorine atom or a methyl group, and m is an integer of 0 to 4. X 1 X is a single bond, a phenylene group, or a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, a lactone ring, a phenylene group, and a naphthylene group. 2 is a single bond, an ester bond, or an amide bond.

[0121] Examples of resist materials include the following:

[0122] A resist material comprising a polymer having a repeating unit represented by the following formula (b1) or (b2):

[0123] [ka] (In formula (b1) and formula (b2), R A is a hydrogen atom or a methyl group. 1 is a single bond or an ester group. 2 is a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms or an arylene group having 6 to 10 carbon atoms, and some of the methylene groups constituting the alkylene group may be substituted with an ether group, an ester group or a lactone ring-containing group; and X 2 At least one hydrogen atom in X is substituted with a bromine atom. 3 Rf is a single bond, an ether group, an ester group, or a linear, branched, or cyclic alkylene group having 1 to 12 carbon atoms, and some of the methylene groups constituting the alkylene group may be substituted with an ether group or an ester group. 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is a fluorine atom or a trifluoromethyl group. 1 and Rf 2 may combine to form a carbonyl group. 1 ~R 5are each independently a linear, branched, or cyclic alkyl group having 1 to 12 carbon atoms, a linear, branched, or cyclic alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or an aryloxyalkyl group having 7 to 12 carbon atoms, in which some or all of the hydrogen atoms may be substituted with a hydroxy group, a carboxy group, a halogen atom, an oxo group, a cyano group, an amido group, a nitro group, a sultone group, a sulfone group, or a sulfonium salt-containing group, and in which some of the methylene groups constituting these groups may be substituted with an ether group, an ester group, a carbonyl group, a carbonate group, or a sulfonate ester group. 1 and R 2 may be bonded to form a ring together with the sulfur atom to which they are attached.

[0124] A resist material comprising a base resin containing a polymer containing a repeating unit represented by the following formula (a):

[0125] [ka] (In formula (a), R A is a hydrogen atom or a methyl group. 1 is a hydrogen atom or an acid labile group. 2 is a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, or a halogen atom other than bromine. 1 X is a single bond, a phenylene group, or a linear, branched, or cyclic alkylene group having 1 to 12 carbon atoms which may contain an ester group or a lactone ring. 2 is -O-, -O-CH2-, or -NH-. m is an integer of 1 to 4. u is an integer of 0 to 3, provided that m+u is an integer of 1 to 4.

[0126] A resist composition that generates an acid upon exposure and whose solubility in a developer changes due to the action of the acid, The composition contains a base component (A) whose solubility in a developer changes under the action of an acid, and a fluorine additive component (F) that is decomposable in an alkaline developer, The fluorine additive component (F) is a resist composition containing a fluorine resin component (F1) having a structural unit (f1) containing a base dissociable group and a structural unit (f2) containing a group represented by the following general formula (f2-r-1):

[0127] [ka] [In formula (f2-r-1), Rf 21 are each independently a hydrogen atom, an alkyl group, an alkoxy group, a hydroxyl group, a hydroxyalkyl group, or a cyano group. n" is an integer of 0 to 2. * is a bond.

[0128] The structural unit (f1) includes a structural unit represented by the following general formula (f1-1) or a structural unit represented by the following general formula (f1-2).

[0129] [ka] [In formulas (f1-1) and (f1-2), each R is independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. X is a divalent linking group that does not have an acid-dissociable site. A aryl X is a divalent aromatic cyclic group which may have a substituent. 01 R is a single bond or a divalent linking group. 2 are each independently an organic group having a fluorine atom.

[0130] Coatings, coating solutions, and coating compositions include, for example:

[0131] A coating comprising a metal oxo-hydroxo network having organic ligands via metal carbon bonds and / or metal carboxylate bonds.

[0132] Inorganic oxo / hydroxyl-based composition.

[0133] A coating solution comprising an organic solvent; a first organometallic composition represented by the formula R z SnO (2-(z / 2)-(x / 2)) (OH) x (where 0 < z ≦ 2 and 0 < (z + x) ≦ 4), the formula R’ n SnX 4-n (where n = 1 or 2), or a mixture thereof, where R and R’ are independently hydrocarbyl groups having 1 to 31 carbon atoms, and X is a ligand having a hydrolyzable bond to Sn or a combination thereof; and a hydrolyzable metal compound represented by the formula MX’ v (where M is a metal selected from Groups 2 to 16 of the Periodic Table of the Elements, v is a number from 2 to 6, and X’ is a ligand having a hydrolyzable M-X bond or a combination thereof), a coating solution containing a hydrolyzable metal compound.

[0134] A coating solution comprising an organic solvent and a first organometallic compound represented by the formula RSnO (3 / 2-x / 2) (OH) x (where 0 < x < 3), wherein the solution contains about 0.0025M to about 1.5M of tin, and R is an alkyl group or a cycloalkyl group having 3 to 31 carbon atoms, and the alkyl group or cycloalkyl group is bonded to tin at a secondary or tertiary carbon atom.

[0135] An inorganic pattern-forming precursor aqueous solution comprising water, a metal oxide cation, a polyatomic inorganic anion, and a mixture with a radiation-sensitive ligand containing a peroxide group.

[0136] Irradiation with EB or EUV is performed, for example, through a mask (reticle) for forming a predetermined pattern. The resist underlayer film of the present invention is applicable for EB (electron beam) or EUV (extreme ultraviolet: 13.5 nm) irradiation, and is preferably applicable for EUV (extreme ultraviolet) exposure. The EB irradiation energy and the EUV exposure dose are not particularly limited.

[0137] After the irradiation with EB or EUV and before development, baking (PEB: Post Exposure Bake) may be performed. The baking temperature is not particularly limited, but is preferably 60°C to 150°C, more preferably 70°C to 120°C, and particularly preferably 75°C to 110°C. The baking time is not particularly limited, but is preferably from 1 second to 10 minutes, more preferably from 10 seconds to 5 minutes, and particularly preferably from 30 seconds to 3 minutes.

[0138] For development, for example, an alkaline developer is used. The development temperature is, for example, 5°C to 50°C. The development time may be, for example, 10 seconds to 300 seconds. Examples of alkaline developers include aqueous solutions of inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia; primary amines such as ethylamine and n-propylamine; secondary amines such as diethylamine and di-n-butylamine; tertiary amines such as triethylamine and methyldiethylamine; alcohol amines such as dimethylethanolamine and triethanolamine; quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline; and cyclic amines such as pyrrole and piperidine. Furthermore, aqueous solutions of the above-mentioned alkalis can be used by adding an appropriate amount of alcohols such as isopropyl alcohol or a nonionic surfactant. Among these, preferred developers are aqueous solutions of quaternary ammonium salts, more preferably aqueous solutions of tetramethylammonium hydroxide and choline. Furthermore, surfactants can also be added to these developers. Instead of an alkaline developer, a method can also be used in which development is performed with an organic solvent such as butyl acetate to develop portions of the photoresist where the alkaline dissolution rate is not improved.

[0139] Next, the resist underlayer film is etched using the formed resist pattern as a mask. The etching may be dry etching or wet etching, but dry etching is preferred. When the inorganic film is formed on the surface of the semiconductor substrate used, the surface of the inorganic film is exposed, and when the inorganic film is not formed on the surface of the semiconductor substrate used, the surface of the semiconductor substrate is exposed. Thereafter, the semiconductor substrate is processed by a known method (dry etching method, etc.), whereby a semiconductor device can be manufactured. [Example]

[0140] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples.

[0141] The weight-average molecular weights of the polymers shown in the following Synthesis Examples 1 to 8 and Comparative Synthesis Example 1 in this specification are the results of measurement by gel permeation chromatography (hereinafter abbreviated as GPC). For the measurement, a GPC device manufactured by Tosoh Corporation was used, and the measurement conditions etc. are as follows. GPC column: TSKgel Super-MultiporeHZ-N (2 columns) Column temperature: 40℃ Solvent: tetrahydrofuran (THF) Flow rate: 0.35ml / min Standard sample: Polystyrene (manufactured by Tosoh Corporation)

[0142] <Synthesis Example 1> 5.68 g of 2-vinylnaphthalene (75% by molar ratio relative to the total polymer 1), 1.60 g of 2-hydroxyethyl methacrylate (25% by molar ratio relative to the total polymer 1), and 0.73 g of 2,2'-azobisisobutyronitrile were dissolved in 32.00 g of propylene glycol monomethyl ether acetate. After replacing the atmosphere in the reaction vessel with nitrogen, the solution was heated and stirred at 140°C for approximately 4 hours. The reaction solution was added dropwise to isopropyl alcohol, and the precipitate was recovered by suction filtration. After that, the precipitate was dried under reduced pressure at 60°C to recover polymer 1. The weight-average molecular weight Mw measured by GPC in terms of polystyrene was 8500. The structure present in polymer 1 is shown in the following formula.

[0143] [ka]

[0144] <Synthesis Example 2> 4.75 g of 2-vinylnaphthalene (55% by molar ratio relative to the total polymer 2), 2.96 g of benzyl methacrylate (30% by molar ratio relative to the total polymer 2), 1.21 g of 2-hydroxypropyl methacrylate (15% by molar ratio relative to the total polymer 2), and 1.07 g of 2,2'-azobisisobutyronitrile were dissolved in 40.00 g of propylene glycol monomethyl ether acetate. After purging the reaction vessel with nitrogen, the solution was heated and stirred at 140°C for approximately 4 hours. The reaction solution was added dropwise to isopropyl alcohol, and the precipitate was recovered by suction filtration. It was then dried under reduced pressure at 60°C to recover polymer 2. The weight-average molecular weight (Mw) measured by GPC in terms of polystyrene was 5900. The structure present in polymer 2 is shown in the following formula.

[0145] [ka]

[0146] <Synthesis Example 3> 10.00 g of 2-vinylnaphthalene (40% by molar ratio relative to the total amount of polymer 3) and 23.00 g of 3-hydroxy-2-adamantyl methacrylate (60% by molar ratio relative to the total amount of polymer 3) were dissolved in 97 g of cyclohexanone in a flask. The atmosphere in the flask was replaced with nitrogen and the temperature was raised to 60°C. After the temperature was raised, a solution of 1.60 g of 2,2'-azobisisobutyronitrile dissolved in 41.00 g of cyclohexanone was added dropwise and stirred for approximately 24 hours. This reaction solution was added dropwise to methanol, and the precipitate was recovered by suction filtration. It was then dried under reduced pressure at 60°C to recover polymer 3. The weight-average molecular weight Mw measured by GPC in terms of polystyrene was 16,000. The structure present in polymer 3 is shown in the following formula.

[0147] [ka]

[0148] <Synthesis Example 4> 10.00 g of 2-vinylnaphthalene (40% by molar ratio relative to the total polymer 4), 17.90 g of 9-anthracenemethyl methacrylate (40% by molar ratio relative to the total polymer 4), and 4.67 g of 2-hydroxyethyl methacrylate (20% by molar ratio relative to the total polymer 4) were dissolved in 95 g of cyclohexanone in a flask. The atmosphere in the flask was replaced with nitrogen and the temperature was raised to 60°C. After the temperature was raised, a solution of 1.60 g of 2,2'-azobisisobutyronitrile dissolved in 41.00 g of cyclohexanone was added dropwise and stirred for approximately 24 hours. This reaction solution was added dropwise to methanol, and the precipitate was collected by suction filtration and then dried under reduced pressure at 60°C to recover polymer 4. The weight-average molecular weight (Mw) measured by GPC in terms of polystyrene was 8,000. The structure present in polymer 4 is shown below.

[0149] [ka]

[0150] <Synthesis Example 5> 2.94 g of 2-vinylnaphthalene (50% by molar ratio relative to the total amount of polymer 5), 1.24 g of hydroxyethyl methacrylate (25% by molar ratio relative to the total amount of polymer 5), 1.71 g of N-cyclohexylmaleimide (25% by molar ratio relative to the total amount of polymer 5), and 0.12 g of 2,2'-azobisisobutyronitrile were dissolved in 24.00 g of propylene glycol monomethyl ether acetate. After purging the reaction vessel with nitrogen, the solution was heated and stirred at 140°C for approximately 4 hours. The reaction solution was added dropwise to isopropyl alcohol, and the precipitate was recovered by suction filtration. It was then dried under reduced pressure at 60°C to recover polymer 5. The weight-average molecular weight (Mw) measured by GPC in terms of polystyrene was 16,300. The structure present in polymer 5 is shown in the following formula.

[0151] [ka]

[0152] <Synthesis Example 6> 2.86 g of 2-vinylnaphthalene (50% by molar ratio relative to the total polymer 6), 1.68 g of N-cyclohexylmaleimide (25% by molar ratio relative to the total polymer 6), 1.32 g of N-hydroxyethylmaleimide (25% by molar ratio relative to the total polymer 6), and 0.12 g of 2,2'-azobisisobutyronitrile were dissolved in 24.00 g of propylene glycol monomethyl ether acetate. After purging the reaction vessel with nitrogen, the solution was heated and stirred at 140°C for approximately 4 hours. The reaction solution was added dropwise to isopropyl alcohol, and the precipitate was recovered by suction filtration. It was then dried under reduced pressure at 60°C to recover polymer 6. The weight-average molecular weight (Mw) measured by GPC in terms of polystyrene was 11,900. The structure present in polymer 6 is shown in the following formula.

[0153] [ka]

[0154] <Synthesis Example 7> To a flask were added 167.27 g of propylene glycol monomethyl ether acetate, 50.00 g of N-phenyl-1-naphthylamine (67% molar ratio relative to the total amount of polymer 7), 20.43 g of N-cyclohexylmaleimide (33% molar ratio relative to the total amount of polymer 7), 21.91 g of methanesulfonic acid, and 1.26 g of hydroquinone, followed by stirring at 140°C for 24 hours. This reaction solution was added dropwise to methanol, and the precipitate was recovered by suction filtration. Polymer 7 was recovered by drying under reduced pressure at 60°C. The weight-average molecular weight Mw measured by GPC in terms of polystyrene was 2000. The structure present in polymer 7 is shown in the following formula.

[0155] [ka]

[0156] <Synthesis Example 8> To a flask were added 54.91 g of propylene glycol monomethyl ether, 15.00 g of carbazole (67% by molar ratio relative to the total amount of polymer 8), 8.04 g of N-cyclohexylmaleimide (33% by molar ratio relative to the total amount of polymer 8), 8.62 g of methanesulfonic acid, and 0.49 g of hydroquinone, followed by stirring at 140°C for 23 hours. This reaction solution was added dropwise to methanol, and the precipitate was recovered by suction filtration and then dried under reduced pressure at 60°C to recover polymer 8. The weight-average molecular weight Mw measured by GPC in terms of polystyrene was 6,000. The structure present in polymer 8 is shown in the following formula.

[0157] [ka]

[0158] <Comparative Synthesis Example 1> 100.00 g of monoallyl diglycidyl isocyanurate (Shikoku Chemicals Corporation), 66.4 g of 5,5-diethylbarbituric acid (Tateyama Chemicals Corporation), and 4.1 g of benzyltriethylammonium chloride were added to 682.00 g of propylene glycol monomethyl ether in a reaction vessel and dissolved. After replacing the atmosphere in the reaction vessel with nitrogen, the reaction was carried out at 130°C for 24 hours to obtain a solution containing comparative polymer 1. GPC analysis showed that the obtained comparative polymer 1 had a weight average molecular weight of 6,800 and a polydispersity of 4.8, calculated as standard polystyrene. The structure present in comparative polymer 1 is shown in the following formula.

[0159] [ka]

[0160] (Preparation of composition for forming resist underlayer film) The components were mixed in the proportions shown in Table 1 and filtered using a polyethylene microfilter with a pore size of 0.05 μm to prepare compositions for forming resist underlayer films of Preparation Examples 1 to 8 and a composition for forming resist underlayer films of Comparative Preparation Example 1.

[0161] The abbreviations in Table 1 are as follows: PyPSA: Pyridinium-p-hydroxybenzenesulfonic acid PGMEA: Propylene glycol monomethyl ether acetate PGME: Propylene glycol monomethyl ether

[0162] PGME-PL:Imidazo[4,5-d]imidazole-2,5(1H,3H)-dione,tetrahydro-1,3,4,6-tetrakis[(2-methoxy-1-methylethoxy)methyl]-(Structural formula below) [ka]

[0163] TMOM-BP: 3,3',5,5'-tetrakis(methoxymethyl)-[1,1'-biphenyl]-4,4'-diol (trade name: TMOM-BP, manufactured by Honshu Chemical Industry Co., Ltd., sub-structural formula) [ka]

[0164] [Table 1]

[0165] (Preparation of resist underlayer film) <Examples 1 to 8 and Comparative Example 1> Each of the resist underlayer film-forming compositions of Preparation Examples 1 to 8 and Comparative Preparation Example 1 was applied onto a silicon wafer using a spinner. The silicon wafer was baked on a hot plate at 205 to 250°C for 60 seconds to obtain 5-nm-thick resist underlayer films of Examples 1 to 8 and Comparative Example 1. The film thickness was measured using an ellipsometric film thickness measuring device RE-3100 (SCREEN Corporation). The resist underlayer film of Example 1 was obtained using the composition for forming the resist underlayer film of Preparation Example 1. The resist underlayer film of Example 2 was obtained using the composition for forming the resist underlayer film of Preparation Example 2. The resist underlayer film of Example 3 was obtained using the composition for forming the resist underlayer film of Preparation Example 3. The resist underlayer film of Example 4 was obtained using the composition for forming the resist underlayer film of Preparation Example 4. The resist underlayer film of Example 5 was obtained using the composition for forming the resist underlayer film of Preparation Example 5. The resist underlayer film of Example 6 was obtained using the composition for forming the resist underlayer film of Preparation Example 6. The resist underlayer film of Example 7 was obtained using the composition for forming the resist underlayer film of Preparation Example 7. The resist underlayer film of Example 8 was obtained using the composition for forming the resist underlayer film of Preparation Example 8. The resist underlayer film of Comparative Example 1 was obtained using the composition for forming the resist underlayer film of Comparative Preparation Example 1.

[0166] (Resist patterning evaluation) <Resist pattern formation test using electron beam lithography equipment> A positive EUV resist solution was spin-coated onto each resist underlayer film of Examples 1 to 8 and Comparative Example 1 formed on a silicon wafer, and the resulting film was heated at 130°C for 60 seconds to form a 35-nm-thick EUV resist film. The resist film was then exposed under specified conditions using an electron beam lithography system (ELS-G130). After exposure, the resist film was baked at 90°C for 60 seconds (PEB), cooled to room temperature on a cooling plate, and puddle developed for 30 seconds using a 2.38% aqueous solution of tetramethylammonium hydroxide (Tokyo Ohka Kogyo Co., Ltd., product name NMD-3) as a photoresist developer. Resist patterns with line sizes of 16 nm to 28 nm were formed. A scanning electron microscope (Hitachi High-Technologies Corporation, CG4100) was used to measure the resist pattern.

[0167] The photoresist pattern thus obtained was observed from above the pattern, and the charge amount forming 22 nm lines / 44 nm pitch (line and space (L / S=1 / 1)) was defined as the optimal irradiation energy. The irradiation energy at that time (μC / cm 2 The LWR, which is a value indicating the roughness of the pattern shape, was checked. LWR is calculated by measuring 400 line positions in the longitudinal direction of the line using a scanning electron microscope (CG4100, manufactured by Hitachi High-Technologies Corporation), and is expressed as three times the standard deviation (σ) (3σ) (unit: nm) calculated from the measurement results. The smaller the LWR value, the better the pattern that can be formed. The results are shown in Table 2.

[0168] As Comparative Example 2, a similar test was carried out using a silicon substrate that had been treated with HMDS (hexamethyldisilazane) without forming a resist underlayer film. The results are shown in Table 2.

[0169] [Table 2]

[0170] In Examples 1 to 8, improvements in LWR were confirmed compared to Comparative Examples 1 and 2. When a resist underlayer film having a thickness of 20 nm or more is used, the resist film thickness is thin, so in the dry etching step after resist pattern formation, the resist pattern is damaged in the process of etching the underlayer film, causing shape defects such as a reduction in resist film thickness and a top-rounding shape, making it difficult to form a pattern with the desired line width during actual substrate processing.

Claims

1. forming a resist underlayer film having a thickness of less than 10 nm on a semiconductor substrate using a composition for forming a resist underlayer film for EB or EUV lithography; forming a resist film on the resist underlayer film using a resist for EB or EUV lithography; irradiating the resist film with EB or EUV light, and then developing the resist film to obtain a resist pattern; etching the resist underlayer film using the resist pattern as a mask; A pattern forming method comprising: The pattern forming method, wherein the composition for forming a resist underlayer film for EB or EUV lithography contains a polymer having a unit structure (A) represented by the following formula (1) and a unit structure (C) derived from a hydroxyalkyl (meth)acrylate: 【Chemistry 1】 (In formula (1), R １ represents a hydrogen atom or a methyl group. X represents an ester group or an amide group. Y represents an alkylene group having 1 to 6 carbon atoms. p and q each independently represent 0 or 1. Ar represents a monovalent group obtained by removing a hydrogen atom from naphthalene, anthracene, phenanthrene, pyrene, triphenylene, chrysene, naphthacene, biphenylene, fluorene, or carbazole, which may be substituted.

2. The pattern forming method according to claim 1 , wherein the unit structure (A) is represented by the following formula (2): 【Chemistry 2】 (In formula (2), R １ represents a hydrogen atom or a methyl group, Z represents a halogen atom, a hydroxyl group, an alkyl group, an alkoxy group, a thiol group, a cyano group, a carboxyl group, an amino group, an amido group, an alkoxycarbonyl group, or a thioalkyl group substituted on a naphthalene ring, and n represents an integer of 0 to 7. When n is 2 or more, two or more Zs may be the same or different.

3. The pattern forming method according to claim 1 , wherein the composition for forming a resist underlayer film for EB or EUV lithography further contains a crosslinking agent.

4. The pattern forming method according to claim 1 , wherein the composition for forming a resist underlayer film for EB or EUV lithography further contains a curing catalyst.

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