Composition for forming lithography underlayer film, lithography underlayer film, positive resist composition, resist film, and method for forming resist pattern

Abstract

The present invention provides: a composition for forming a lithography underlayer film, the composition containing a polymer that contains a repeating unit derived from an iodine-containing monomer represented by general formula (1); and a positive resist composition which contains a polymer that contains a repeating unit derived from an iodine-containing monomer represented by formula (1). (In the formula, X1 is a hydrogen atom, a methyl group, or a halogen atom, Y1 is -O- or -NH-, a is 0 or 1, and R is a group containing an iodine atom and 2 to 30 carbon atoms.)

Description

Lithography underlayer film-forming composition, lithography underlayer film, positive resist composition, resist film, and method for forming a resist pattern

[0001] The present invention relates to a lithography underlayer film-forming composition, a lithography underlayer film, a positive resist composition, a resist film, and a method for forming a resist pattern.

[0002] In the manufacture of semiconductor devices, microfabrication is performed by lithography using photoresist materials. However, in recent years, with the increasing integration and speed of LSIs (large-scale integrated circuits), further miniaturization using pattern rules is required. Conventional resist materials have been polymer-based resist materials capable of forming amorphous thin films. Examples of polymer-based resist materials include polymethyl methacrylate, polyhydroxystyrene or polyalkyl methacrylate having an acid-dissociable group. Recently, photoresist materials capable of further miniaturizing patterns have been developed. For example, Patent Document 1 discloses a lithography composition containing a resin having structural units derived from a compound having specific amounts of iodine, tellurium, and fluorine atoms as a highly sensitive material.

[0003] International Publication No. 2021 / 157551

[0004] It is difficult to improve sensitivity with conventionally used lithography materials. Furthermore, previously developed high-sensitivity lithography materials have problems such as insufficient pattern quality, including pattern defects and large roughness, and insufficient etching resistance. In light of these circumstances, there has been a demand for lithography materials with higher sensitivity while addressing the above-mentioned problems. Therefore, a first problem to be solved by the present invention is to provide a lithography underlayer film-forming composition, a lithography underlayer film, and a method for forming a resist pattern, which are capable of improving the exposure sensitivity in the lithography process. Furthermore, a second problem to be solved by the present invention is to provide a positive resist composition that has excellent resolution, etching resistance, and resist sensitivity characteristics, as well as a resist film and a method for forming a resist pattern using the same.

[0005] The present inventors have found that the first problem can be solved by a lithography underlayer film-forming composition that contains a polymer that includes a repeating unit derived from a specific iodine-containing monomer.

[0006] The present inventors have discovered that the second problem can be solved by a positive resist composition that includes a polymer that contains a repeating unit derived from a specific iodine-containing monomer.

[0007] That is, the present invention is as follows: <1> A composition for forming a lithography underlayer film, comprising a polymer containing a repeating unit derived from an iodine-containing monomer represented by the following general formula (1A). (In the formula, X 1A is a hydrogen atom, a methyl group or a halogen atom, and Y 1A is —O— or —NH—, aa is 0 or 1, and R A is an organic group having 2 to 30 carbon atoms and containing an iodine atom. A is an organic group represented by the following general formula (2A): (In the formula, L A represents a direct bond or a divalent organic group having 1 to 24 carbon atoms. ba represents an integer of 1 to 5. A is at least one selected from the group consisting of an organic group represented by the following general formula (3A) and an organic group represented by the following general formula (4A): (In the formula, L A is a direct bond or a divalent organic group having 1 to 24 carbon atoms.) <4> The lithography underlayer film-forming composition according to any one of <1> to <3> above, further containing a solvent. <5> The lithography underlayer film-forming composition according to any one of <1> to <4> above, further containing at least one selected from the group consisting of an acid generator and an acid crosslinker. <6> A lithography underlayer film formed from the lithography underlayer film-forming composition according to <5> above. <7> A method for forming a resist pattern, using the lithography underlayer film-forming composition according to <5> above.

[0008] <8> A positive resist composition comprising a polymer containing a repeating unit derived from an iodine-containing monomer represented by the following formula (1B): (In the formula, X 1B is a hydrogen atom, a methyl group, or a halogen atom; Y 1B is —O— or —NH—, ab is 0 or 1, and R B is a group containing an iodine atom and having 2 to 30 carbon atoms. B is a group represented by the following formula (2B): (In the formula, L B is a direct bond or a divalent group having 1 to 24 carbon atoms, and R １B are each independently an alkyl group having 1 to 30 carbon atoms which may have a substituent, an aryl group having 6 to 30 carbon atoms which may have a substituent, an alkenyl group having 2 to 30 carbon atoms which may have a substituent, an alkynyl group having 2 to 30 carbon atoms which may have a substituent, an alkoxy group having 1 to 30 carbon atoms which may have a substituent, a halogen atom other than iodine, a nitro group, an amino group, a carboxylic acid group, a crosslinkable group, a dissociable group, a thiol group, or a hydroxyl group. bb is an integer of 1 to 5, cb is an integer of 0 to 4, and bb + cb is 1 to 5.) <10>R B is at least one selected from the group consisting of a group represented by the following formula (3B) and a group represented by the following formula (4B): (In the formula, L Bis a direct bond or a divalent group having 1 to 24 carbon atoms.) <11> The positive resist composition according to any one of <8> to <10> above, wherein the polymer further contains a repeating unit derived from a phenolic hydroxyl group-containing monomer. <12> The positive resist composition according to <11> above, wherein the phenolic hydroxyl group-containing monomer is at least one selected from the group consisting of 4-vinylphenol, 4-hydroxyphenyl(meth)acrylate, and 4-hydroxyphenyl(meth)acrylamide. <13> The positive resist composition according to <11> or <12> above, wherein the phenolic hydroxyl group-containing monomer is 4-vinylphenol. <14> The positive resist composition according to any one of the above <11> to <13>, wherein the molar ratio of the repeating units derived from the phenolic hydroxyl group-containing monomer to the repeating units derived from the iodine-containing monomer represented by formula (1B) [phenolic hydroxyl group-containing monomer / iodine-containing monomer] is 20 / 80 to 95 / 5. <15> The positive resist composition according to any one of the above <8> to <14>, wherein the polymer further contains a repeating unit derived from an adamantane structure-containing monomer. <16> The positive resist composition according to the above <15>, wherein the adamantane structure-containing monomer is at least one selected from the group consisting of adamantan-1-yl(meth)acrylate, 2-methyladamantan-2-yl(meth)acrylate, 2-ethyladamantan-2-yl(meth)acrylate, and N-(1-adamantyl)(meth)acrylamide. <17> The positive resist composition according to <15> or <16> above, wherein the adamantane structure-containing monomer is 2-methyladamantan-2-yl(meth)acrylate. <18> The positive resist composition according to any one of <15> to <17> above, wherein the molar ratio of repeating units derived from the adamantane structure-containing monomer to repeating units derived from the iodine-containing monomer represented by formula (1B) [adamantane structure-containing monomer / iodine-containing monomer] is 20 / 80 to 99 / 1. <19> The positive resist composition according to any one of <8> to <18> above, further comprising a solvent.<20> The positive resist composition according to any one of <8> to <19> above, further comprising at least one selected from the group consisting of an acid generator and a crosslinking agent. <21> A resist film formed from the positive resist composition according to any one of <8> to <20> above. <22> A method for forming a resist pattern using the positive resist composition according to any one of <8> to <20> above. <23> A method for forming a resist pattern, comprising: forming a resist film on a substrate using the positive resist composition according to any one of <8> to <20> above; and irradiating the resist film with radiation to perform development.

[0009] According to the first aspect of the present invention, it is possible to provide a lithography underlayer film-forming composition and a lithography underlayer film that can increase the exposure sensitivity in a lithography process. It is also possible to provide a method for forming a resist pattern. Furthermore, according to the second aspect of the present invention, it is possible to provide a positive resist composition that exhibits excellent resolution, etching resistance, and resist sensitivity characteristics, a resist film using the same, and a method for forming a resist pattern.

[0010] [Lithography Underlayer Film-Forming Composition (First Invention)] The lithography underlayer film-forming composition in the first invention of the present invention is a lithography underlayer film-forming composition containing a polymer containing a repeating unit derived from an iodine-containing monomer represented by the following general formula (1A): (In the formula, X 1A is a hydrogen atom, a methyl group or a halogen atom, and Y 1A is —O— or —NH—, aa is 0 or 1, and R A is an organic group having 2 to 30 carbon atoms and containing an iodine atom.) Hereinafter, "the present invention" means "the first invention of the present invention," "the second invention of the present invention," or an invention including both "the first invention of the present invention" and "the second invention of the present invention."

[0011] That is, the lithography underlayer film-forming composition of the present invention is a lithography underlayer film-forming composition containing the above-mentioned polymer, and the above-mentioned polymer is a polymer containing a repeating unit derived from the iodine-containing monomer represented by the above-mentioned general formula (1A).

[0012] <Polymer> The polymer contained in the lithography underlayer film-forming composition of the present invention is a polymer containing a repeating unit derived from an iodine-containing monomer represented by the following general formula (1A). The polymer may be linear or branched, but is preferably linear. Furthermore, the polymer may contain a single repeating unit derived from one type of iodine-containing monomer, or may contain repeating units derived from two or more types of iodine-containing monomers. By including the polymer in the lithography underlayer film-forming composition of the present invention, the exposure sensitivity in the lithography process can be increased. (In the formula, X 1A is a hydrogen atom, a methyl group or a halogen atom, and Y 1A is —O— or —NH—, aa is 0 or 1, and R A is an organic group having 2 to 30 carbon atoms and containing an iodine atom.

[0013] The reason why the lithography underlayer film-forming composition and lithography underlayer film of the present invention can increase the exposure sensitivity in the lithography process is unclear, but it is thought to be as follows. In particular, when EUV is used as the lithography light source, despite the fact that EUV is easily transmitted through resist films and tends to reduce exposure sensitivity, the underlayer film of the present invention containing an iodine-containing polymer can absorb EUV light and supply secondary electrons and protons to the resist layer, thereby improving the sensitivity of the resist. Furthermore, by using a lithography underlayer film-forming composition containing the above-mentioned polymer as the underlayer film of the resist layer, it is thought that collapse of the resist pattern and deterioration of the resist pattern shape are suppressed, enabling higher resolution. In this way, it is thought that use of the lithography underlayer film-forming composition and lithography underlayer film of the present invention can increase the exposure sensitivity in the lithography process.

[0014] (Iodine-containing monomer represented by formula (1A)) The iodine-containing monomer used as a raw material for the polymer is represented by the following general formula (1A). (In the formula, X 1A is a hydrogen atom, a methyl group or a halogen atom, and Y 1A is —O— or —NH—, aa is 0 or 1, and R A is an organic group having 2 to 30 carbon atoms and containing an iodine atom.

[0015] In formula (1A), X 1A is a hydrogen atom, a methyl group or a halogen atom, preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom. 1A is —O— or —NH—, preferably —O—. In formula (1A), aa is 0 or 1, preferably 1.

[0016] In formula (1A), R Ais an organic group having 2 to 30 carbon atoms and containing an iodine atom, preferably an organic group represented by the following general formula (2A), more preferably at least one selected from the group consisting of an organic group represented by the following general formula (3A) and an organic group represented by the following general formula (4A), and even more preferably an organic group represented by the following general formula (3A). In particular, by selecting a monomer having an organic group represented by formula (3A), it is possible to obtain a polymer that is excellent in molecular weight controllability, solubility, and film formability. (In formula (2A), L A represents a direct bond or a divalent organic group having 1 to 24 carbon atoms. ba represents an integer of 1 to 5. In formula (3A), L A is a direct bond or a divalent organic group having 1 to 24 carbon atoms. A is a direct bond or a divalent organic group having 1 to 24 carbon atoms.

[0017] In formula (2A), ba is an integer of 1 to 5, preferably an integer of 1 to 3, more preferably 1 or 3, and even more preferably 3. In particular, by selecting a monomer having a triiodophenyl group in which ba is 3, a polymer excellent in molecular weight controllability, solubility, and film-forming properties can be obtained. When ba is 3, L A The triiodophenyl group bonded to is preferably a 2,3,5-triiodophenyl group or a 2,4,6-triiodophenyl group, more preferably a 2,4,6-triiodophenyl group.

[0018] L in formula (2A), formula (3A) and formula (4A) A may be the same or different, but each is preferably a direct bond. A are divalent organic groups having 1 to 24 carbon atoms, they may be the same or different, but the preferred organic groups are the same. The divalent organic group having 1 to 24 carbon atoms may be an aliphatic group or an aromatic group, preferably an aliphatic group, and more preferably an alkylene group or a (poly)oxyalkylene group. A is an alkylene group, L AThe number of carbon atoms in L is preferably 1 to 24, more preferably 2 to 24. A is a (poly)oxyalkylene group, L A The number of oxygen atoms in L is preferably 1 to 12. A The number of carbon atoms in L is preferably 1 to 24, more preferably 2 to 24. A is a (poly)oxyalkylene group, L A is preferably a (poly)oxyethylene group, a (poly)oxypropylene group or a (poly)oxybutylene group, more preferably a (poly)oxyethylene group.

[0019] (Other Monomers) As a raw material for the polymer, other monomers may be used in addition to the iodine-containing monomer. That is, the lithography underlayer film-forming composition of the present invention may be a lithography underlayer film-forming composition containing a polymer containing a repeating unit derived from the iodine-containing monomer represented by formula (1A) and a repeating unit derived from a monomer other than the iodine-containing monomer. The polymer may contain one type of repeating unit derived from the other monomer alone, or may contain two or more types of repeating units derived from the other monomers.

[0020] Examples of other monomers besides the iodine-containing monomer represented by formula (1A) include (meth)acrylate-based monomers, styrene-based monomers, (meth)acrylamide-based monomers, nitrile group-containing vinyl monomers, vinyl halides, vinylidene halides, vinyl acetate, etc., and (meth)acrylate-based monomers are preferred. By including a (meth)acrylate-based monomer other than the iodine-containing monomer represented by formula (1A), film-forming properties are improved.

[0021] Examples of styrene-based monomers include styrene, p-methylstyrene, α-methylstyrene, halogenated styrene, vinylbenzoic acid, 4-vinylbenzenesulfonic acid, 4-vinylbenzenesulfonic acid ester, 4-vinylbenzenesulfonic acid amide, etc. Examples of (meth)acrylamide-based monomers include (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, etc. Examples of nitrile group-containing vinyl monomers include (meth)acrylonitrile, etc.

[0022] Examples of the (meth)acrylate monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N-t-butylaminoethyl (meth)acrylate, and polyalkylene glycol (meth)acrylate. Among these, preferred are 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, and polyalkylene glycol (meth)acrylate, more preferred are 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, and polyethylene glycol (meth)acrylate, even more preferred are 2-hydroxyethyl (meth)acrylate and polyalkylene glycol (meth)acrylate, and still more preferred is polyalkylene glycol (meth)acrylate.

[0023] The polyalkylene glycol (meth)acrylate is preferably polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, or polybutylene glycol (meth)acrylate, more preferably polyethylene glycol (meth)acrylate or polypropylene glycol (meth)acrylate, and even more preferably polyethylene glycol (meth)acrylate.

[0024] (Molecular Weight Control Agent) A molecular weight control agent may be used as a raw material for the polymer. That is, the lithography underlayer film-forming composition of the present invention may be a lithography underlayer film-forming composition containing a polymer containing a repeating unit derived from the iodine-containing monomer represented by formula (1A) and a structure derived from a molecular weight control agent, or may be a lithography underlayer film-forming composition containing a polymer containing a repeating unit derived from the iodine-containing monomer represented by formula (1A), a repeating unit derived from a monomer other than the iodine-containing monomer, and a structure derived from a molecular weight control agent. Note that the polymer may contain one type of structure derived from the molecular weight control agent alone, or may contain two or more types of structures derived from the molecular weight control agent.

[0025] The molecular weight control agent is an additive capable of suppressing polymerization and controlling the molecular weight range, and is typically a chain transfer agent. The molecular weight control agent is preferably an aromatic compound. Examples of molecular weight control agents include various chain transfer agents, RAFT agents, NMP agents, ATRP agents, and TERP agents, and sulfur-containing chain transfer agents such as thiol-type chain transfer agents and RAFT agents are preferred. These may be used alone or in combination of two or more.

[0026] The thiol-type chain transfer agent may be a monothiol compound, a dithiol compound, a trithiol compound, or a tetrathiol or higher polythiol compound, but is preferably a monothiol compound or a dithiol compound. The thiol-type chain transfer agent may be a thiol compound having a sulfur atom in addition to the thiol group. The thiol compound may be a molecule consisting only of carbon, hydrogen, and sulfur. Specific examples of the thiol-type chain transfer agent include aliphatic monothiol compounds, aliphatic polythiol compounds, aliphatic thiols containing sulfur atoms in addition to mercapto groups, aromatic monothiol compounds, aromatic polythiols, aromatic polythiol compounds containing sulfur atoms in addition to mercapto groups, heterocyclic compounds containing sulfur atoms in addition to mercapto groups, compounds containing hydroxy groups in addition to mercapto groups, and derivatives thereof. Aromatic monothiol compounds and aromatic polythiol compounds containing sulfur atoms in addition to mercapto groups are preferred, and bis(4-mercaptophenyl)sulfide (4,4'-thiobisbenzenethiol) and 4-mercaptopyridine are more preferred. These may be used alone or in combination of two or more.

[0027] Examples of the aliphatic monothiol compound include methanethiol, ethanethiol, propanethiol, butanethiol, and cyclohexanethiol. Examples of aliphatic polythiol compounds include methanedithiol, 1,2-ethanedithiol, 1,1-propanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 2,2-propanedithiol, 1,6-hexanedithiol, 1,2,3-propanetrithiol, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2-methylcyclohexane-2,3-dithiol, 1,1-bis(mercaptomethyl)cyclohexane, thiomalic acid bis(2-mercaptoethyl ester), 2,3-dimercapto-1-propanol(2-mercaptoacetate), 2,3-dimercapto-1-propanol(3-mercaptopropionate), dimercapto-1-propanol(2-mercaptoacetate), di ... Examples of the mercaptosilane include ethylene glycol bis(2-mercaptoacetate), diethylene glycol bis(3-mercaptopropionate), 1,2-dimercaptopropyl methyl ether, 2,3-dimercaptopropyl methyl ether, 2,2-bis(mercaptomethyl)-1,3-propanedithiol, bis(2-mercaptoethyl)ether, ethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), trimethylolpropane bis(2-mercaptoacetate), trimethylolpropane bis(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(3-mercaptopropionate), and tetrakis(mercaptomethyl)methane.

[0028] Examples of aliphatic thiols containing a sulfur atom in addition to a mercapto group include bis(mercaptomethyl)sulfide, bis(mercaptoethyl)sulfide, bis(mercaptopropyl)sulfide, bis(mercaptomethylthio)methane, bis(2-mercaptoethylthio)methane, bis(3-mercaptopropyl)methane, 1,2-bis(mercaptomethylthio)ethane, 1,2-(2-mercaptoethylthio)ethane, 1,2-(3-mercaptopropyl)ethane, 1,3-bis(mercaptomethylthio)propane, 1,3-bis(2-mercaptoethylthio)propane, 1,3-bis(3-mercaptopropylthio)propane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, and 2-mercaptoethylthio-1,3-propanedithiol. , 1,2,3-tris(mercaptomethylthio)propane, 1,2,3-tris(2-mercaptoethylthio)propane, 1,2,3-tris(3-mercaptopropylthio)propane, tetrakis(mercaptomethylthiomethyl)methane, tetrakis(2-mercaptoethylthiomethyl)methane, tetrakis(3-mercaptopropylthiomethyl)methane, bis(2,3-dimercaptopropyl)sulfide, 2,5-dimercapto-1,4-dithiane, bis(mercaptomethyl)disulfide, bis(mercaptoethyl)disulfide, bis(mercaptopropyl)disulfide, 4-mercaptomethyl-3,6-dithiaoctane-1,8-dithiol, bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol, bis(1,3-dimercapto-2-propyl) sulfide, hydroxymethyl sulfide bis(2-mercaptoacetate), hydroxymethyl sulfide bis(3-mercaptopropionate), hydroxyethyl sulfide bis(2-mercaptoacetate), hydroxyethyl sulfide bis(3-mercaptopropionate), hydroxypropyl sulfide bis(2-mercaptoacetate), hydroxypropyl sulfide bis(3-mercaptopropionate), hydroxymethyl disulfide bis(2-mercaptoacetate), hydroxymethyl disulfide bis(3-mercaptopropionate), hydroxyethyl disulfide bis(2-mercaptoacetate), hydroxyethyl disulfide bis(3-mercaptopropionate), hydroxypropyl disulfide bis(2-mercaptoacetate), hydroxypropyl disulfide bis(3-mercaptopropionate), 2-mercaptoethyl ether bis(2-mercaptoethyl ether 2-mercaptoethyl ether bis(3-mercaptopropionate), 1,4-dithiane-2,5-diol bis(2-mercaptoacetate), 1,4-dithiane-2,5-diol bis(3-mercaptopropionate), thioglycolic acid bis(2-mercaptoethyl ester), thiodipropionic acid bis(2-mercaptoethyl ester), 4,4'-thiodibutyric acid bis(2-mercaptoethyl ester), dithiodiglycolic acid bis (2-mercaptoethyl ester), dithiodipropionic acid bis(2-mercaptoethyl ester), 4,4'-dithiodibutyric acid bis(2-mercaptoethyl ester), thiodiglycolic acid bis(2,3-dimercaptopropyl ester), thiodipropionic acid bis(2,3-dimercaptopropyl ester), dithiodiglycolic acid bis(2,3-dimercaptopropyl ester), dithiodipropionic acid (2,3-dimercaptopropyl ester), and the like.

[0029] Examples of aromatic monothiol compounds include benzenethiol, o-methyl-α-toluenethiol, o-toluenethiol, m-toluenethiol, p-toluenethiol, 1-naphthalenethiol, 2-naphthalenethiol, and 4-mercaptopyridine, with 4-mercaptopyridine being preferred. Examples of aromatic polythiols include 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, 1,2-bis(mercaptoethyl)benzene, 1,3-bis(mercaptoethyl)benzene, 1,4-bis(mercaptoethyl)benzene, 1,2,3-trimercaptobenzene, 1,2,4-trimercaptobenzene, 1,3,5-trimercaptobenzene, and 1,2,3-tris(mercaptomethyl)benzene. Examples include benzene, 1,2,4-tris(mercaptomethyl)benzene, 1,3,5-tris(mercaptomethyl)benzene, 1,2,3-tris(mercaptoethyl)benzene, 1,2,4-tris(mercaptoethyl)benzene, 1,3,5-tris(mercaptoethyl)benzene, 2,5-toluenedithiol, 3,4-toluenedithiol, 1,3-di(p-methoxyphenyl)propane-2,2-dithiol, 1,3-diphenylpropane-2,2-dithiol, phenylmethane-1,1-dithiol, and 2,4-di(p-mercaptophenyl)pentane.

[0030] Examples of aromatic polythiol compounds containing sulfur atoms in addition to mercapto groups include 1,2-bis(mercaptomethylenethio)benzene, 1,3-bis(mercaptomethylenethio)benzene, 1,4-bis(mercaptomethylenethio)benzene, 1,2-bis(mercaptoethylenethio)benzene, 1,3-bis(mercaptoethylenethio)benzene, 1,4-bis(mercaptoethylenethio)benzene, 1,2-bis(mercaptopropylenethio)benzene, 1,3-bis(mercaptopropylenethio)benzene, and 1,4-bis(mercaptopropylenethio). Benzene, 1,2-bis(mercaptoethylenethiomethylene)benzene, 1,3-bis(mercaptoethylenethiomethylene)benzene, 1,4-bis(mercaptoethylenethiomethylene)benzene, 1,2-bis(mercaptopropylenethiomethylene)benzene, 1,3-bis(mercaptopropylenethiomethylene)benzene, 1,4-bis(mercaptopropylenethiomethylene)benzene, bis(4-mercaptophenyl)sulfide (4,4'-thiobisbenzenethiol), bis(3-mercaptophenyl)sulfide, 4,4'-oxybisbenzene thiol, 4,4'-biphenyldithiol, 1,2-bis(mercaptomethyleneoxy)benzene, 1,3-bis(mercaptomethyleneoxy)benzene, 1,4-bis(mercaptomethyleneoxy)benzene, 1,2-bis(mercaptoethyleneoxy)benzene, 1,3-bis(mercaptoethyleneoxy)benzene, 1,4-bis(mercaptoethyleneoxy)benzene, 1,2-bis(mercaptoethyleneoxymethylene)benzene, 1,3-bis(mercaptoethyleneoxymethylene)benzene, 1,4-bis(mercaptoethyleneoxy)benzene methylene)benzene, 1,2-bis(mercaptopropyleneoxymethylene)benzene, 1,3-bis(mercaptopropyleneoxymethylene)benzene, 1,4-bis(mercaptopropyleneoxymethylene)benzene, 1,3,5-trimercaptobenzene, 1,2,3-tris(mercaptomethylthio)benzene, 1,2,4-tris(mercaptomethylthio)benzene, 1,3,5-tris(mercaptomethylthio)benzene, 1,2,3-tris(mercaptoethylthio)benzene, 1,2,4-tris(mercaptoethylthio)benzene, 1,3,5-tris(mercaptoethylthio)benzene, and bis(4-mercaptophenyl)sulfide (4,4'-thiobisbenzenethiol) is preferred.

[0031] Examples of heterocyclic compounds containing a sulfur atom in addition to a mercapto group include 3,4-thiophenedithiol and 2,5-dimercapto-1,3,4-thiadiazole. Examples of compounds containing a hydroxy group in addition to a mercapto group include 2-mercaptoethanol, 3-mercapto-1,2-propanediol, glycerin di(mercaptoacetate), 1-hydroxy-4-mercaptocyclohexane, 2,4-dimercaptophenol, 2-mercaptohydroquinone, 4-mercaptophenol, 3,4-dimercapto-2-propanol, 1,3-dimercapto-2-propanol, 2,3-dimercapto-1-propanol, and 1,2-dimercapto-1,3 -butanediol, pentaerythritol tris(3-mercaptopropionate), pentaerythritol mono(3-mercaptopropionate), pentaerythritol bis(3-mercaptopropionate), pentaerythritol tris(thioglycolate), dipentaerythritol pentakis(3-mercaptopropionate), hydroxymethyl-tris(mercaptoethylthiomethyl)methane, 1-hydroxyethylthio-3-mercaptoethylthiobenzene, and the like.

[0032] Specific examples of RAFT agents include dithioesters, trithiocarbonates, dithiocarbamates, and disulfides. These may be used alone or in combination of two or more. Examples of dithioesters include 2-cyano-2-propylbenzodithioate and 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid. Examples of trithiocarbonates include 2-cyano-2-propyldodecyltrithiocarbonate, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid, and cyanomethyldodecyltrithiocarbonate. Examples of dithiocarbamates include cyanomethylmethyl(phenyl)carbamodithioate. Examples of disulfides include bis(thiobenzoyl)disulfide and bis(dodecylsulfanylthiocarbonyl)disulfide.

[0033] (Polymer Composition) The content of the repeating unit derived from the iodine-containing monomer represented by formula (1A) in the polymer is preferably 20 to 100 mass%, more preferably 40 to 100 mass%, even more preferably 50 to 100 mass%, still more preferably 70 to 100 mass%, and even more preferably 80 to 100 mass%. The polymer may consist solely of repeating units derived from the iodine-containing monomer represented by formula (1A), but is even more preferably 80 to 90 mass%.

[0034] When the polymer contains a repeating unit derived from a (meth)acrylate monomer other than the iodine-containing monomer represented by formula (1A), the content of the repeating unit derived from the (meth)acrylate monomer in the polymer is preferably 1 to 80 mass%, more preferably 3 to 60 mass%, even more preferably 5 to 50 mass%, still more preferably 6 to 30 mass%, still more preferably 8 to 20 mass%, and even more preferably 10 to 20 mass%. By containing a (meth)acrylate monomer other than the iodine-containing monomer represented by formula (1A) in the above range, film-formability is improved.

[0035] When the polymer contains a repeating unit derived from a (meth)acrylate monomer other than the iodine-containing monomer represented by formula (1A), the content of the repeating unit derived from the iodine-containing monomer represented by formula (1A) in the polymer is preferably 20 to 99 mass%, more preferably 40 to 97 mass%, even more preferably 50 to 95 mass%, still more preferably 70 to 92 mass%, still more preferably 80 to 92 mass%, and still more preferably 80 to 90 mass%.

[0036] When the polymer contains a repeating unit derived from a (meth)acrylate monomer other than the iodine-containing monomer represented by formula (1A), the molar ratio of the repeating unit derived from the iodine-containing monomer represented by formula (1A) to the repeating unit derived from the (meth)acrylate monomer [iodine-containing monomer / (meth)acrylate monomer] is preferably 20 / 80 to 99 / 1, more preferably 40 / 60 to 97 / 3, even more preferably 50 / 50 to 95 / 5, still more preferably 70 / 30 to 92 / 8, still more preferably 80 / 20 to 92 / 8, and still more preferably 80 / 20 to 90 / 10.

[0037] When the polymer contains a structure derived from a molecular weight control agent, the content of the structure derived from the molecular weight control agent in the polymer is preferably 1 to 80% by mass, more preferably 3 to 60% by mass, even more preferably 5 to 50% by mass, still more preferably 6 to 30% by mass, even more preferably 8 to 20% by mass, and still more preferably 10 to 20% by mass.

[0038] When the polymer contains a structure derived from a molecular weight control agent, the content of the repeating unit derived from the iodine-containing monomer represented by formula (1A) in the polymer is preferably 20 to 99% by mass, more preferably 40 to 97% by mass, even more preferably 50 to 95% by mass, still more preferably 70 to 92% by mass, still more preferably 80 to 92% by mass, and still more preferably 80 to 90% by mass.

[0039] When the polymer contains a structure derived from a molecular weight control agent, the molar ratio of the repeating unit derived from the iodine-containing monomer represented by formula (1A) to the structure derived from the molecular weight control agent [iodine-containing monomer / molecular weight control agent] is preferably 20 / 80 to 99 / 1, more preferably 40 / 60 to 97 / 3, even more preferably 50 / 50 to 95 / 5, still more preferably 70 / 30 to 92 / 8, still more preferably 80 / 20 to 92 / 8, and still more preferably 80 / 20 to 90 / 10.

[0040] (Molecular Weight of Polymer) The number average molecular weight of the polymer is preferably 500 to 100,000, more preferably 1,000 to 50,000, even more preferably 2,000 to 40,000, still more preferably 3,000 to 30,000, still more preferably 5,000 to 25,000, still more preferably 10,000 to 20,000, and still more preferably 10,000 to 15,000. When the number average molecular weight of the polymer is within the above range, the solubility and film-forming properties of the polymer become excellent. The number average molecular weight is a polystyrene-equivalent molecular weight.

[0041] The molecular weight distribution (Mw / Mn) of the polymer is preferably 1.3 to 7.5, more preferably 1.3 to 7.0, even more preferably 1.3 to 6.0, still more preferably 1.3 to 5.0, still more preferably 1.3 to 4.0, still more preferably 1.3 to 3.0, still more preferably 1.5 to 3.0, and still more preferably 2.0 to 3.0.

[0042] <Method for Producing Polymer> The polymer contained in the lithography underlayer film-forming composition of the present invention may be produced by any method without limitation, as long as it contains a polymer containing a repeating unit derived from an iodine-containing monomer represented by formula (1A). However, the following method is preferred.

[0043] The polymer can be produced by polymerizing the above-mentioned monomers as raw materials. The polymer may be produced by polymerizing the monomers in the presence of a molecular weight control agent. Polymerizing the monomers in the presence of a molecular weight control agent can control the molecular weight, and the resulting polymer can have a desired molecular weight.

[0044] The polymerization method in the above step is not particularly limited. Examples of the polymerization method include bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc., with solution polymerization being preferred. Examples of the polymerization method include radical polymerization, anionic polymerization, and cationic polymerization, with radical polymerization being preferred. An appropriate polymerization method can be selected depending on the type of monomer, polymerization temperature, etc.

[0045] In the polymerization in the above step, it is preferable to use a polymerization initiator. The polymerization initiator can be selected depending on the type of monomer, the polymerization temperature, etc. Examples of the polymerization initiator include azo initiators and peroxide initiators, with azo initiators being preferred. Examples of azo initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,2-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), and 2,2'-azobis(2-amidinopropane) dihydrochloride, with 2,2'-azobisisobutyronitrile being preferred. Examples of peroxide initiators include benzoyl peroxide, di-t-butyl hydroperoxide, t-butyl hydroperoxide, cumyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, benzoyl peroxide, dicumyl peroxide, ethyl 3,3-di(t-amylperoxy)butyrate, potassium sulfate, ammonium persulfate, etc. The polymerization initiators may be used alone or in combination of two or more.

[0046] The amount of the polymerization initiator used may be appropriately changed depending on the type of monomer and the type of polymerization initiator, but is preferably 0.1 to 50 mol %, more preferably 0.5 to 30 mol %, even more preferably 1 to 20 mol %, still more preferably 2 to 10 mol %, and still more preferably 3 to 5 mol %, based on the total amount of the monomers.

[0047] When the polymerization in the above step is carried out by solution polymerization, it is preferable to select an appropriate solvent in consideration of the solubility of the monomer and polymerization initiator, the polymerization temperature, etc., and to carry out the polymerization in that solvent. Examples of solvents used in the above step include DMF, N-methyl-2-pyrrolidone, acetone, THF, benzene, toluene, ethylbenzene, xylene, chlorobenzene, methyl ethyl ketone, ethyl lactate, isopropyl alcohol, etc. These may be used alone or in combination of two or more.

[0048] The amount of the raw material monomer used may be changed so as to obtain a polymer of the desired composition. Specifically, the following amounts are preferred. The amount of the iodine-containing monomer represented by formula (1A) used is preferably 20 to 100% by mass, more preferably 40 to 100% by mass, even more preferably 50 to 100% by mass, still more preferably 70 to 100% by mass, and even more preferably 80 to 100% by mass, based on the total amount of the monomer and the molecular weight control agent. The amount may consist solely of the iodine-containing monomer represented by formula (1A), but is even more preferably 80 to 90% by mass.

[0049] When the raw material monomer contains a (meth)acrylate monomer other than the iodine-containing monomer represented by formula (1A), the amount of the (meth)acrylate monomer used is preferably 1 to 80 mass %, more preferably 3 to 60 mass %, even more preferably 5 to 50 mass %, still more preferably 6 to 30 mass %, still more preferably 8 to 20 mass %, and even more preferably 10 to 20 mass %, based on the total amount of the monomer and the molecular weight control agent. By using a (meth)acrylate monomer other than the iodine-containing monomer represented by formula (1A), film formability is improved.

[0050] When the raw material monomer contains a (meth)acrylate monomer other than the iodine-containing monomer represented by formula (1A), the amount of the iodine-containing monomer represented by formula (1A) used is preferably 20 to 99 mass%, more preferably 40 to 97 mass%, even more preferably 50 to 95 mass%, still more preferably 70 to 92 mass%, still more preferably 80 to 92 mass%, and still more preferably 80 to 90 mass%, based on the total amount of the monomer and the molecular weight control agent.

[0051] When the raw material monomer contains a (meth)acrylate monomer other than the iodine-containing monomer represented by formula (1A), the molar ratio of the iodine-containing monomer represented by formula (1A) to the (meth)acrylate monomer [iodine-containing monomer / (meth)acrylate monomer] is preferably 20 / 80 to 99 / 1, more preferably 40 / 60 to 97 / 3, even more preferably 50 / 50 to 95 / 5, still more preferably 70 / 30 to 92 / 8, still more preferably 80 / 20 to 92 / 8, and still more preferably 80 / 20 to 90 / 10.

[0052] When the raw material contains a molecular weight control agent, the amount of the molecular weight control agent used is preferably 1 to 80 mass %, more preferably 3 to 60 mass %, even more preferably 5 to 50 mass %, still more preferably 6 to 30 mass %, still more preferably 8 to 20 mass %, and still more preferably 10 to 20 mass %, based on the total amount of the monomer and the molecular weight control agent.

[0053] When a molecular weight control agent is contained in the raw material, the amount of the iodine-containing monomer represented by formula (1A) used is preferably 20 to 99 mass%, more preferably 40 to 97 mass%, even more preferably 50 to 95 mass%, still more preferably 70 to 92 mass%, still more preferably 80 to 92 mass%, and still more preferably 80 to 90 mass%, based on the total amount of the monomer and the molecular weight control agent.

[0054] When the raw material contains a molecular weight control agent, the molar ratio of the iodine-containing monomer represented by formula (1A) to the molecular weight control agent [iodine-containing monomer / molecular weight control agent] is preferably 20 / 80 to 99 / 1, more preferably 40 / 60 to 97 / 3, even more preferably 50 / 50 to 95 / 5, still more preferably 70 / 30 to 92 / 8, still more preferably 80 / 20 to 92 / 8, and still more preferably 80 / 20 to 90 / 10.

[0055] The reaction temperature may be adjusted appropriately depending on the decomposition temperature of the polymerization initiator used, but is preferably 0 to 100° C., more preferably 20 to 80° C., even more preferably 30 to 70° C., still more preferably 40 to 70° C., and even more preferably 50 to 70° C. The reaction time may be adjusted appropriately depending on the reaction temperature, amount of catalyst, reactivity of raw materials, target molecular weight, and the like, but is preferably 1 to 72 hours, more preferably 5 to 60 hours, even more preferably 12 to 50 hours, still more preferably 15 to 40 hours, and even more preferably 15 to 30 hours.

[0056] The reaction may be carried out in the presence of a solvent. Preferred solvents are those in which the resulting polymer dissolves, more preferably amide solvents, and even more preferably N,N-dimethylformamide. The resulting polymer is preferably purified by conventional post-treatment. Specifically, it is preferable to remove raw materials and by-products by pouring the reaction mixture into an organic solvent in which the polymer does not dissolve and recovering the target polymer as a precipitate. It is also preferable to dissolve the polymer in an organic solvent in which the polymer dissolves and wash with water or the like to remove the catalyst, etc. If the polymer is obtained as a solution in an organic solvent at the end of the reaction or purification treatment, it is preferable to concentrate and dry the polymer to obtain a solid. The polymer obtained in this manner has high solubility in solvents and excellent film-forming properties.

[0057] <Composition of Lithography Underlayer Film-Forming Composition> The lithography underlayer film-forming composition of the present invention preferably further contains a solvent in addition to the polymer, and preferably contains at least one selected from the group consisting of an acid generator and an acid crosslinker. Other optional components may also be included, such as an acid or base compound, an acid diffusion controller, an organic polymer compound, a surfactant, a colorant, and a curing catalyst. From the viewpoints of coatability and quality stability, the content of the polymer in the lithography underlayer film-forming composition is preferably 0.1 to 70% by mass, more preferably 0.5 to 50% by mass, and even more preferably 3.0 to 40% by mass.

[0058]

[0042] From the viewpoint of improving film-forming properties, the lithography underlayer film-forming composition of the present invention preferably further contains a solvent. The solvent is not particularly limited as long as it dissolves other components such as the polymer, but the following solvents are preferred.Examples of the solvent include ethylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, and ethylene glycol mono-n-butyl ether acetate; ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate, and propylene glycol mono-n-butyl ether acetate; propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether (1-methoxy-2-propanol, PGME) and propylene glycol monoethyl ether; lactic acid esters such as methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, and n-amyl lactate; methyl acetate, ethyl acetate, n-propyl acetate, and n-butyl acetate. aliphatic carboxylic acid esters such as methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl 3-methoxy-2-methylpropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, butyl 3-methoxy-3-methylpropionate, butyl 3-methoxy-3-methylbutyrate, methyl acetoacetate, methyl pyruvate, ethyl pyruvate, and other esters such as methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-methoxybutyl acetate, methyl 3-methoxy-3-methylpropionate, butyl 3-methoxy-3-methylbutyrate, methyl acetoacetate, methyl pyruvate, and ethyl pyruvate; aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone (MEK), 2-heptanone, 3-heptanone, 4-heptanone, cyclopentanone (CPN), and cyclohexanone (CHN); amides such as N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpyrrolidone; lactones such as γ-lactone; sulfoxides such as dimethyl sulfoxide (DMSO); halogenated hydrocarbons such as chloroform; and cyclic ethers such as tetrahydrofuran (THF).These solvents may be used alone or in combination with one another. The solvent contained in the lithography underlayer film-forming composition of the present invention is preferably a safe solvent, more preferably at least one selected from PGMEA, PGME, CHN, CPN, 2-heptanone, anisole, butyl acetate, ethyl propionate, and ethyl lactate, and even more preferably at least one selected from PGMEA, PGME, and CHN. From the viewpoints of solubility and film formation, the content of the solvent in the lithography underlayer film-forming composition of the present invention is preferably 100 to 10,000 parts by mass, more preferably 200 to 8,000 parts by mass, and even more preferably 200 to 5,000 parts by mass, relative to 100 parts by mass of the total solid components (components excluding the solvent) of the lithography underlayer film-forming composition.

[0059] (Acid Generator) The lithography underlayer film-forming composition of the present invention preferably contains at least one selected from the group consisting of an acid generator and an acid crosslinker, and more preferably contains both an acid generator and an acid crosslinker. The acid generator is preferably an acid generator that generates an acid directly or indirectly upon irradiation with any radiation selected from visible light, ultraviolet light, an excimer laser, an electron beam, extreme ultraviolet light (EUV), X-rays, and an ion beam. In the lithography underlayer film-forming composition of the present invention, the content of the acid generator is preferably 0.001 to 49% by mass, more preferably 1 to 40% by mass, even more preferably 3 to 30% by mass, and still more preferably 10 to 25% by mass, based on the total mass of the solid components (components excluding the solvent). By having the acid generator content within the above range, a pattern profile with high sensitivity and low edge roughness can be obtained. In the lithography underlayer film-forming composition of the present invention, the method for generating an acid is not limited as long as an acid is generated in the system. If an excimer laser is used instead of ultraviolet rays such as g-rays or i-rays, finer processing is possible, and if electron beams, extreme ultraviolet rays, X-rays, or ion beams are used as high-energy rays, even finer processing is possible.

[0060] The acid generator is not particularly limited, and examples thereof include the compounds disclosed in WO 2017 / 033943. The acid generator is preferably an acid generator having an aromatic ring, more preferably an acid generator having a sulfonate ion with an aryl group, and even more preferably at least one selected from the group consisting of diphenyltrimethylphenylsulfonium p-toluenesulfonate, triphenylsulfonium p-toluenesulfonate, triphenylsulfonium trifluoromethanesulfonate, and triphenylsulfonium nonafluoromethanesulfonate. Use of the acid generator can reduce line edge roughness.

[0061] The lithography underlayer film-forming composition of the present invention preferably further contains a diazonaphthoquinone photoactive compound as an acid generator. The diazonaphthoquinone photoactive compound is a diazonaphthoquinone substance, including polymeric and non-polymeric diazonaphthoquinone photoactive compounds. It is not particularly limited as long as it is a diazonaphthoquinone substance generally used as a photosensitive component in positive resist compositions, and one or more types may be arbitrarily selected and used. Among these, from the viewpoints of low roughness and solubility, non-polymeric diazonaphthoquinone photoactive compounds are preferred, and low-molecular-weight compounds are more preferred. The molecular weight is preferably 1,500 or less, more preferably 1,200 or less, and even more preferably 1,000 or less. Preferred specific examples of such non-polymeric diazonaphthoquinone photoactive compounds include the non-polymeric diazonaphthoquinone photoactive compounds disclosed in WO 2016 / 158881. The acid generators can be used alone or in combination.

[0062] (Acid Crosslinking Agent) The lithography underlayer film-forming composition of the present invention preferably contains an acid crosslinking agent to increase the strength of the pattern, whether it is used as a negative resist material or a positive resist material. An acid crosslinking agent is a compound that can intramolecularly or intermolecularly crosslink a polymer (resin) in the presence of an acid generated from an acid generator. Examples of such acid crosslinking agents include, but are not limited to, compounds having one or more crosslinkable groups that can crosslink a polymer (resin). Specific examples of crosslinkable groups include, but are not limited to, (i) hydroxyalkyl groups such as hydroxy (alkyl groups having 1 to 6 carbon atoms), alkoxy (alkyl groups having 1 to 6 carbon atoms), and acetoxy (alkyl groups having 1 to 6 carbon atoms), or groups derived therefrom; (ii) carbonyl groups such as formyl groups and carboxy (alkyl groups having 1 to 6 carbon atoms), or groups derived therefrom; (iii) dimethylaminomethyl groups, diethylaminomethyl groups, dimethylolaminomethyl groups, diethylaminomethyl groups, and the like. (iv) glycidyl group-containing groups such as a glycidyl ether group, a glycidyl ester group, and a glycidylamino group; (v) groups derived from aromatic groups such as allyloxy (an alkyl group having 1 to 6 carbon atoms) and aralkyloxy (an alkyl group having 1 to 6 carbon atoms) having 1 to 6 carbon atoms, such as a benzyloxymethyl group and a benzoyloxymethyl group; and (vi) polymerizable multiple bond-containing groups such as a vinyl group and an isopropenyl group. Examples of the crosslinkable group include hydroxyalkyl groups and alkoxyalkyl groups, and more preferably an alkoxymethyl group.

[0063] The acid crosslinking agent is not particularly limited, but examples thereof include (i) methylol group-containing compounds such as methylol group-containing melamine compounds, methylol group-containing benzoguanamine compounds, methylol group-containing urea compounds, methylol group-containing glycoluril compounds, and methylol group-containing phenol compounds; (ii) alkoxyalkyl group-containing compounds such as alkoxyalkyl group-containing melamine compounds, alkoxyalkyl group-containing benzoguanamine compounds, alkoxyalkyl group-containing urea compounds, alkoxyalkyl group-containing glycoluril compounds, and alkoxyalkyl group-containing phenol compounds; (iii) carboxymethyl group-containing compounds such as carboxymethyl group-containing melamine compounds, carboxymethyl group-containing benzoguanamine compounds, carboxymethyl group-containing urea compounds, carboxymethyl group-containing glycoluril compounds, and carboxymethyl group-containing phenol compounds; and (iv) epoxy compounds such as bisphenol A-based epoxy compounds, bisphenol F-based epoxy compounds, bisphenol S-based epoxy compounds, novolac resin-based epoxy compounds, resole resin-based epoxy compounds, and poly(hydroxystyrene)-based epoxy compounds. As the acid crosslinking agent, a compound having a phenolic hydroxyl group, or a compound or resin in which the crosslinkable group is introduced into an acidic functional group in an alkali-soluble resin to impart crosslinkability, can be used. In this case, the introduction rate of the crosslinkable group is not particularly limited, and is preferably 5 to 100 mol %, more preferably 10 to 60 mol %, and even more preferably 15 to 40 mol %, based on the total acidic functional groups in the compound having a phenolic hydroxyl group and the alkali-soluble resin. This range is preferable because it allows the crosslinking reaction to occur sufficiently, preventing a decrease in the residual film rate and preventing phenomena such as swelling and meandering of the pattern.

[0064] In the lithography underlayer film-forming composition of the present invention, the acid crosslinker is preferably at least one selected from an alkoxyalkylated urea compound or a resin thereof, or an alkoxyalkylated glycoluril compound or a resin thereof (acid crosslinker (1)); a phenol derivative having 1 to 6 benzene rings in the molecule and having two or more hydroxyalkyl groups or alkoxyalkyl groups throughout the molecule, with the hydroxyalkyl groups or alkoxyalkyl groups bonded to any of the benzene rings (acid crosslinker (2)); and a compound having at least one α-hydroxyisopropyl group (acid crosslinker (3)). Examples of such compounds include those disclosed in WO 2017 / 033943. In the lithography underlayer film-forming composition of the present invention, the content of the acid crosslinker is preferably 0.5 to 49% by mass, more preferably 0.5 to 40% by mass, even more preferably 1 to 30% by mass, and still more preferably 2 to 20% by mass, based on the total mass of the solid components (components excluding the solvent). A content of the acid crosslinker of 0.5% by mass or more is preferable because it improves the effect of suppressing the solubility of the resist film in an alkaline developer, thereby suppressing a decrease in the residual film rate and the occurrence of swelling or meandering of the pattern. Furthermore, a content of 49% by mass or less is preferable because it can suppress a decrease in the heat resistance of the resist. Furthermore, the contents of the acid crosslinker (1), acid crosslinker (2), and acid crosslinker (3) in the acid crosslinker are not particularly limited and can be selected depending on the type of substrate used when forming the resist pattern, etc.

[0065] [Lithography Underlayer Film] The polymer contained in the lithography underlayer film-forming composition of the present invention has high solubility in solvents and excellent film-forming properties, so it is preferable to form a lithography underlayer film using the lithography underlayer film-forming composition. Therefore, the rectangularity of the pattern is excellent. Furthermore, due to the excellent film-forming properties, a good resist pattern shape can be imparted. Furthermore, the lithography underlayer film-forming composition can form a lithography underlayer film with high flatness. That is, the lithography underlayer film of the present invention is a lithography underlayer film formed from the lithography underlayer film-forming composition. The lithography underlayer film of the present invention can be suitably used as a lower layer (resist underlayer film) of a photoresist (upper layer) used in a multilayer resist method.

[0066] The method for forming the lithography underlayer film of the present invention is not particularly limited as long as it is formed from the lithography underlayer film-forming composition, and known methods can be applied. For example, the lithography underlayer film can be formed by applying the lithography underlayer film-forming composition to a substrate by a known coating method or printing method such as spin coating or screen printing, and then removing the organic solvent.

[0067] The composition can also be suitably used in a multilayer resist method in which a resist underlayer film is further provided between an upper-layer resist (e.g., photoresist) and a hard mask or organic underlayer film. In such a multilayer resist method, for example, a resist underlayer film is formed on a substrate via an organic underlayer film or hard mask by a coating method or the like, and an upper-layer resist (e.g., photoresist, electron beam resist, EUV resist) is formed on the resist underlayer film. A resist pattern is then formed by exposure and development, and the resist underlayer film is dry-etched using the resist pattern to transfer the pattern. The organic underlayer film is then etched to transfer the pattern, and the substrate is processed using the organic underlayer film. That is, the lithography underlayer film (resist underlayer film) of the present invention formed using the lithography underlayer film-forming composition is less likely to intermix with the upper-layer resist, has heat resistance, and can form a good rectangular pattern. The position (which layer it is stacked in) of the resist underlayer film formed using the lithography underlayer film-forming composition of the present invention is not particularly limited, and it may be directly below the upper resist layer, may be the layer located closest to the substrate, or may be sandwiched between resist underlayer films.

[0068] When forming fine patterns, the resist film thickness tends to be thin to prevent pattern collapse. Dry etching for transferring a pattern to an underlying film by thinning the resist requires a higher etching rate than the overlying film in order to achieve pattern transfer. A substrate can be coated with an organic underlayer film, which is then coated with the lithography underlayer film of the present invention, and this can then be coated with a resist film (organic resist film). For example, using the pattern-transferred resist underlayer film, the underlying organic underlayer film can be dry-etched with an oxygen-based gas to transfer the pattern to the organic underlayer film, and the pattern-transferred organic underlayer film can then be used to process the substrate using a halogen-containing gas. Furthermore, the lithography underlayer film of the present invention has high heat resistance and can be used under high-temperature baking conditions. Furthermore, because of its relatively low molecular weight and low viscosity, it is easy to uniformly fill even substrates with steps (especially those with fine spaces or hole patterns), resulting in relatively favorable improvements in planarization and filling properties.

[0069] More specifically, a preferred method for forming a lithography underlayer film is the method described in the "step of forming an underlayer film" in the pattern formation method described below.

[0070] [Method of forming a resist pattern (method of forming a resist pattern using a lithography underlayer film-forming composition)] As described above, the lithography underlayer film-forming composition is excellent as a material for forming a lithography underlayer film. Therefore, a resist pattern is preferably formed by a method of forming a resist pattern including a step of forming a lithography underlayer film on a substrate using the lithography underlayer film-forming composition. That is, the pattern formation method of the present invention is a method of forming a resist pattern using a lithography underlayer film-forming composition. More specifically, a suitable pattern formation method of the present invention is a method of forming a resist pattern including a step of forming an underlayer film precursor on a substrate using the lithography underlayer film-forming composition and heating the underlayer film precursor to 300°C or higher to form an underlayer film, a step of forming at least one photoresist layer on the underlayer film, and a step of irradiating the photoresist layer with radiation and developing it.

[0071] <Process for forming underlayer film> The process for forming an underlayer film is a process for forming an underlayer film precursor on a substrate using the lithography underlayer film-forming composition, and heating the underlayer film precursor to 300°C or higher to form an underlayer film.

[0072] The substrate used in this step can be a semiconductor substrate. As the semiconductor substrate, a silicon substrate can generally be used, but is not particularly limited thereto, and examples thereof include Si, amorphous silicon (α-Si), p-Si, SiO ２ , SiN, SiON, W, TiN, Al, or the like, which is different from the material of the processed layer. When a semiconductor substrate is used, a metal film, a metal carbide film, a metal oxide film, a metal nitride film, a metal carbide oxide film, or a metal oxynitride film formed on the semiconductor substrate can be used as the processed layer (processed portion). Examples of such a processed layer containing a metal include Si, SiO ２, SiN, SiON, SiOC, p-Si, α-Si, TiN, WSi, BPSG, SOG, Cr, CrO, CrON, MoSi, W, W-Si, Al, Cu, Al-Si, etc., as well as various low dielectric films and their etching stopper films, can be used, and can be formed to a thickness of usually 50 to 10,000 nm, particularly 100 to 5,000 nm.

[0073] This process involves forming an underlayer film on a substrate using the lithography underlayer film-forming composition. However, before forming the underlayer film using the lithography underlayer film-forming composition, an organic underlayer film or an organic hard mask can be formed on the substrate. The organic underlayer film can be formed from a coating-type organic underlayer film material using a spin-coating method or the like, and the organic hard mask can be formed from an organic hard mask material primarily composed of carbon using a CVD method. The types of such organic underlayer films and organic hard masks are not particularly limited, but when the top-layer resist film is to be patterned by exposure, those that exhibit sufficient anti-reflective coating function are preferred. By forming such an organic underlayer film or organic hard mask, the pattern formed in the top-layer resist film can be transferred onto the substrate (workpiece) without causing size conversion differences. A "carbon-based" hard mask refers to a hard mask in which 50% or more by mass of the solid content is composed of a carbon-based material, such as amorphous hydrogenated carbon, also known as amorphous carbon and denoted as a-C:H. While a-C:H films can be deposited by various techniques, plasma enhanced chemical vapor deposition (PECVD) is widely used due to its cost-effectiveness and film quality tunability. Examples of such hard masks include those described in JP 2013-526783 A. When forming an organic underlayer film on a substrate, this process involves forming an organic underlayer film on the substrate, forming an underlayer film precursor on the organic underlayer film using the lithography underlayer film-forming composition, and heating the underlayer film precursor to 300°C or higher to form an underlayer film. When forming an organic hard mask on a substrate, this process involves forming an organic hard mask on the substrate, forming an underlayer film precursor on the organic hard mask using the lithography underlayer film-forming composition, and heating the underlayer film precursor to 300°C or higher to form an underlayer film.

[0074] The method for forming an underlayer film precursor using the lithography underlayer film-forming composition is preferably to form it on a substrate or a workpiece provided with an organic underlayer film or the like by spin coating or the like. When forming the lithography underlayer film-forming composition on a substrate or a workpiece by spin coating, the lithography underlayer film-forming composition is first applied to the substrate or the workpiece. The content of the polymer contained in the lithography underlayer film-forming composition may be appropriately adjusted taking into account the spin coating rotation speed, rotation time, viscosity of the composition, and evaporation rate of the solvent. The content of the polymer contained in the lithography underlayer film-forming composition is preferably 0.001 to 10 g per 100 mL of solvent contained in the lithography underlayer film-forming composition. Next, the organic solvent is removed by volatilization to form an underlayer film precursor. The film thickness of the underlayer film precursor is preferably adjusted to 1 to 200 nm by adjusting the polymer content, spin coating rotation speed, rotation time, etc. Furthermore, when forming the underlayer film, a bake treatment is preferably performed in which the underlayer film is heated to 300°C or higher in order to suppress the occurrence of mixing with the upper layer resist and to promote the crosslinking reaction. In this case, the bake temperature is preferably 300°C or higher, more preferably 300 to 450°C, and even more preferably 300 to 400°C. The bake time is not particularly limited, but is preferably 10 to 300 seconds. In this manner, the underlayer film is formed on the substrate. The thickness of the underlayer film can be appropriately selected depending on the required performance and is not particularly limited, but is preferably 30 to 20,000 nm, and more preferably 50 to 15,000 nm.

[0075] <Step of Forming Photoresist Layer> Next, the step of forming a photoresist layer is carried out. The step of forming a photoresist layer is a step of forming at least one photoresist layer on the underlayer film.

[0076] This process forms a photoresist layer on the underlayer film. Examples of photoresist materials used for the photoresist layer include those that form a photoresist film, expose it, and then dissolve the exposed areas using an alkaline developer to form a positive pattern, or those that dissolve the unexposed areas using an organic solvent developer to form a negative pattern. When forming a photoresist layer using a photoresist material, wet processes such as spin coating and screen printing are preferably used. After applying the photoresist material using a spin coating method or the like, pre-baking is typically performed. This pre-baking is preferably performed under conditions of a baking temperature of 80 to 180°C and a baking time of 10 to 300 seconds. The thickness of the photoresist layer is not particularly limited, but is generally preferably 30 to 500 nm, more preferably 50 to 400 nm.

[0077] <Developing Step> Next, the developing step is performed. The developing step is a step of irradiating the photoresist layer with radiation and developing it, and in this step, by performing exposure and development as described above, a resist pattern can be obtained.

[0078] The radiation (exposure light) irradiated onto the photoresist layer may be appropriately selected depending on the photoresist material used. Generally, high-energy radiation with a wavelength of 300 nm or less, specifically, excimer lasers with wavelengths of 248 nm, 193 nm, or 157 nm, soft X-rays with wavelengths of 3 to 20 nm, electron beams, X-rays, etc., may be used. As a method for forming a pattern, any of the following methods can be suitably used: lithography using light with a wavelength of 300 nm or less or EUV light; electron beam direct writing; and directed self-assembly. By using such methods, fine patterns can be formed. The development method may be appropriately selected depending on the photoresist material used as the raw material for the photoresist layer. When a positive pattern is formed, it is preferable to dissolve the exposed portions using an alkaline developer to form a positive pattern. When a negative pattern is formed, it is preferable to dissolve the unexposed portions using a developer composed of an organic solvent to form a negative pattern. A resist pattern can be obtained in this manner.

[0079]

[0023] Furthermore, the pattern formation method of the present invention preferably includes the steps of: using the resist pattern formed on the upper layer as described above as a mask to transfer a pattern to an underlayer film by etching, using the resist underlayer film to which the pattern has been transferred as a mask to transfer the pattern to the organic underlayer film by etching, and further using the organic underlayer film to which the pattern has been transferred as a mask to transfer the pattern to the substrate (workpiece) by etching.

[0024] Furthermore, as another aspect of the pattern formation method of the present invention, the pattern formation method of the present invention preferably includes the steps of: using the resist pattern formed on the upper layer as described above as a mask to transfer a pattern to the underlayer film by etching, using the underlayer film to which the pattern has been transferred as a mask to transfer the pattern to the organic hard mask by etching, and further using the organic hard mask to which the pattern has been transferred as a mask to transfer the pattern to the substrate (workpiece) by etching.

[0080] [Positive Resist Composition (Second Invention)] The positive resist composition according to the second invention is a positive resist composition that contains a polymer that contains a repeating unit derived from an iodine-containing monomer represented by the following formula (1B): (In the formula, X 1B is a hydrogen atom, a methyl group, or a halogen atom; Y 1B is —O— or —NH—, ab is 0 or 1, and R B is a group containing an iodine atom and having 2 to 30 carbon atoms.) Hereinafter, "the present invention" means "the first invention of the present invention," "the second invention of the present invention," or an invention including both "the first invention of the present invention" and "the second invention of the present invention."

[0081] That is, the positive resist composition of the present invention is a positive resist composition that contains a polymer, wherein the polymer contains a repeating unit derived from the iodine-containing monomer represented by formula (1B). The polymer containing the repeating unit derived from the iodine-containing monomer represented by formula (1B) exhibits excellent solvent solubility, heat resistance, and film-forming properties, and also has good developability in a developer such as an alkaline developer, making it an excellent material for forming a lithography film, and particularly an excellent material for forming a resist film.

[0082] <Polymer> The polymer contained in the positive resist composition of the present invention is a polymer containing a repeating unit derived from an iodine-containing monomer represented by the following formula (1B). The polymer may be linear or branched, but is preferably linear. Furthermore, the polymer may contain a single repeating unit derived from one type of iodine-containing monomer, or may contain repeating units derived from two or more types of iodine-containing monomers. By including the polymer in the positive resist composition of the present invention, it is possible to improve the resolution and etching resistance, and also to improve the resist sensitivity characteristics. (In the formula, X 1B is a hydrogen atom, a methyl group or a halogen atom, and Y 1B is —O— or —NH—, ab is 0 or 1, and R Bis a group containing an iodine atom and having 2 to 30 carbon atoms.

[0083] The reason why the positive resist composition and resist film of the present invention exhibit excellent resolution, etching resistance, and resist sensitivity characteristics is unclear, but it is thought to be as follows. It is believed that the resist film of the present invention, which contains an iodine-containing polymer, is able to absorb irradiated light and supply secondary electrons and protons, thereby improving the sensitivity of the resist. Furthermore, it is believed that by using a positive resist composition containing this polymer as a resist film, deterioration of the resist pattern shape is suppressed, making it possible to achieve even higher resolution.

[0084] (Iodine-containing monomer represented by formula (1B)) The iodine-containing monomer used as a raw material for the polymer is represented by the following formula (1B). (In the formula, X 1B is a hydrogen atom, a methyl group, or a halogen atom; Y 1B is —O— or —NH—, ab is 0 or 1, and R B is a group containing an iodine atom and having 2 to 30 carbon atoms.

[0085] In formula (1B), X 1B is a hydrogen atom, a methyl group, or a halogen atom, preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom. １B When Y is a hydrogen atom, a positive resist composition containing a polymer made from an iodine-containing monomer represented by formula (1B) as a raw material exhibits excellent exposure sensitivity. 1B is —O— or —NH—, preferably —O—. In formula (1B), ab is 0 or 1, preferably 1.

[0086] In formula (1B), R B is a group containing an iodine atom and having 2 to 30 carbon atoms, and is preferably a group represented by the following formula (2B): (In the formula, L B is a direct bond or a divalent group having 1 to 24 carbon atoms, and R １Bare each independently an alkyl group having 1 to 30 carbon atoms which may have a substituent, an aryl group having 6 to 30 carbon atoms which may have a substituent, an alkenyl group having 2 to 30 carbon atoms which may have a substituent, an alkynyl group having 2 to 30 carbon atoms which may have a substituent, an alkoxy group having 1 to 30 carbon atoms which may have a substituent, a halogen atom other than iodine, a nitro group, an amino group, a carboxylic acid group, a crosslinkable group, a dissociable group, a thiol group, or a hydroxyl group. bb is an integer from 1 to 5, cb is an integer from 0 to 4, and bb + cb is 1 to 5.

[0087] In formula (2B), R １B are each independently an alkyl group having 1 to 30 carbon atoms which may have a substituent, an aryl group having 6 to 30 carbon atoms which may have a substituent, an alkenyl group having 2 to 30 carbon atoms which may have a substituent, an alkynyl group having 2 to 30 carbon atoms which may have a substituent, an alkoxy group having 1 to 30 carbon atoms which may have a substituent, a halogen atom other than iodine, a nitro group, an amino group, a carboxylic acid group, a crosslinkable group, a dissociable group, a thiol group, or a hydroxyl group. bb is an integer of 1 to 5, preferably an integer of 1 to 3, more preferably 1 or 3, and even more preferably 3. cb is an integer of 0 to 4, preferably 0. bb + cb is 1 to 5, preferably 1 to 3, more preferably 1 or 3, and even more preferably 3. L B is a direct bond or a divalent group having 1 to 24 carbon atoms. B is preferably a direct bond. When a polymer contains a plurality of repeating units derived from an iodine-containing monomer represented by formula (1B), L B may be the same or different, but are preferably the same. More preferably, all L B is a direct bond. The divalent group having 1 to 24 carbon atoms may be an aliphatic group or an aromatic group, preferably an aliphatic group, and more preferably an alkylene group or a (poly)oxyalkylene group. B is an alkylene group, L B The number of carbon atoms in L is preferably 1 to 24, more preferably 2 to 24. Bis a (poly)oxyalkylene group, L B The number of oxygen atoms in L is preferably 1 to 12. B The number of carbon atoms in L is preferably 1 to 24, more preferably 2 to 24. B is a (poly)oxyalkylene group, L B is preferably a (poly)oxyethylene group, a (poly)oxypropylene group or a (poly)oxybutylene group, more preferably a (poly)oxyethylene group.

[0088] The dissociable group refers to a group that dissociates under specific conditions, and includes an acid-dissociable group that dissociates in the presence of acid, a heat-dissociable group that dissociates by heating, and a photodissociable group that dissociates by light irradiation, and the like, with the acid-dissociable group being preferred. Specific examples of the acid-dissociable group include those described in WO 2016 / 158168. The crosslinkable group refers to a group that can crosslink intramolecularly or intermolecularly, and specific examples of the crosslinkable group include those described in WO 2020 / 226150.

[0089] The group represented by formula (2B) is more preferably a group represented by the following formula (2aB), more preferably at least one selected from the group consisting of a group represented by the following formula (3B) and a group represented by the following formula (4B), and even more preferably a group represented by the following formula (3B): In particular, by selecting a monomer having a group represented by formula (3B), it is possible to obtain a polymer that is excellent in molecular weight controllability, solubility, and film-forming property. (In formula (2aB), L B is a direct bond or a divalent group having 1 to 24 carbon atoms. bb is an integer of 1 to 5. In formula (3B), L B is a direct bond or a divalent group having 1 to 24 carbon atoms. B is a direct bond or a divalent group having 1 to 24 carbon atoms.

[0090] In formula (2aB), bb is an integer of 1 to 5, preferably an integer of 1 to 3, more preferably 1 or 3, and even more preferably 3. In particular, by selecting a monomer having a triiodophenyl group in which bb is 3, a polymer excellent in molecular weight controllability, solubility, and film-forming properties can be obtained. When bb is 3, L B The triiodophenyl group bonded to is preferably a 2,3,5-triiodophenyl group or a 2,4,6-triiodophenyl group, more preferably a 2,4,6-triiodophenyl group.

[0091] L in formula (2aB), formula (3B), and formula (4B) B is a direct bond or a divalent group having 1 to 24 carbon atoms. B In the case where a polymer contains a plurality of repeating units derived from the iodine-containing monomers represented by formula (2aB), formula (3B), and formula (4B), L in formula (2aB), formula (3B), and formula (4B) are preferably direct bonds. B may be the same or different, but are preferably the same. More preferably, all L B is a direct bond. The divalent group having 1 to 24 carbon atoms may be an aliphatic group or an aromatic group, preferably an aliphatic group, and more preferably an alkylene group or a (poly)oxyalkylene group. B is an alkylene group, L B The number of carbon atoms in L is preferably 1 to 24, more preferably 2 to 24. B is a (poly)oxyalkylene group, L B The number of oxygen atoms in L is preferably 1 to 12. B The number of carbon atoms in L is preferably 1 to 24, more preferably 2 to 24. B is a (poly)oxyalkylene group, L B is preferably a (poly)oxyethylene group, a (poly)oxypropylene group, or a (poly)oxybutylene group, and more preferably a (poly)oxyethylene group.

[0092] (Other Monomers) As raw materials for the polymer, monomers other than the iodine-containing monomer represented by formula (1B) may be used. That is, the positive resist composition of the present invention may be a positive resist composition that contains a polymer that contains a repeating unit derived from the iodine-containing monomer represented by formula (1B) and a repeating unit derived from a monomer other than the iodine-containing monomer represented by formula (1B). The polymer may contain a single type of repeating unit derived from the other monomer, or may contain two or more types of repeating units derived from the other monomers.

[0093] The polymer contained in the positive resist composition of the present invention is a polymer containing a repeating unit derived from an iodine-containing monomer represented by formula (1B), and is preferably a polymer that further contains a repeating unit derived from a phenolic hydroxyl group-containing monomer. By further containing a repeating unit derived from a phenolic hydroxyl group-containing monomer, adhesion to the substrate is improved, and film-forming properties are also improved.

[0094] Examples of phenolic hydroxyl group-containing monomers include 4-vinylphenol, 4-hydroxyphenyl(meth)acrylate, and 4-hydroxyphenyl(meth)acrylamide, with 4-vinylphenol being preferred. Because the phenolic hydroxyl group can affect the polymerization reaction, it is preferable to protect the phenolic hydroxyl group during polymerization and then deprotect it after polymerization to introduce a repeating unit derived from the phenolic hydroxyl group-containing monomer. Examples of protecting groups for the phenolic hydroxyl group include benzyl, methoxymethyl, trialkylsilyl, acyl, benzoyl, and trityl groups, with methoxymethyl, trialkylsilyl, acyl, benzoyl, and trityl being preferred, and methoxymethyl and acyl being more preferred. For example, when introducing a repeating unit derived from 4-vinylphenol into a polymer, 4-vinylphenyl acetate is used as a starting material for polymerization, followed by deprotection by hydrolysis to introduce the repeating unit derived from 4-vinylphenol into the polymer.

[0095] The polymer contained in the positive resist composition of the present invention is a polymer containing a repeating unit derived from an iodine-containing monomer represented by formula (1B), and is preferably a polymer that further contains a repeating unit derived from a monomer having an adamantane structure. By further containing a repeating unit derived from a monomer having an adamantane structure, the polymer is more easily decomposable by acid and has improved developability, making it possible to form fine patterns. Examples of the adamantane structure-containing monomer include adamantan-1-yl(meth)acrylate, 2-methyladamantan-2-yl(meth)acrylate, 2-ethyladamantan-2-yl(meth)acrylate, and N-(1-adamantyl)(meth)acrylamide, and is preferably at least one selected from the group consisting of adamantan-1-yl(meth)acrylate, 2-methyladamantan-2-yl(meth)acrylate, and 2-ethyladamantan-2-yl(meth)acrylate, and more preferably 2-methyladamantan-2-yl(meth)acrylate.

[0096] Examples of other monomers besides the above-mentioned monomers include (meth)acrylate-based monomers, styrene-based monomers, (meth)acrylamide-based monomers, nitrile group-containing vinyl monomers, vinyl halides, vinylidene halides, and vinyl acetate, and preferably (meth)acrylate-based monomers.

[0097] Examples of styrene-based monomers include styrene, p-methylstyrene, α-methylstyrene, halogenated styrene, vinylbenzoic acid, 4-vinylbenzenesulfonic acid, 4-vinylbenzenesulfonic acid ester, 4-vinylbenzenesulfonic acid amide, etc. Examples of (meth)acrylamide-based monomers include (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, etc. Examples of nitrile group-containing vinyl monomers include (meth)acrylonitrile, etc.

[0098] Examples of the (meth)acrylate monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N-t-butylaminoethyl (meth)acrylate, and polyalkylene glycol (meth)acrylate, and preferably 2-hydroxyethyl (meth)acrylate, ( The alkyl acrylate is at least one selected from the group consisting of 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, and polyalkylene glycol (meth)acrylate, more preferably at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, and polyethylene glycol (meth)acrylate, even more preferably at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate and polyalkylene glycol (meth)acrylate, and still more preferably polyalkylene glycol (meth)acrylate.

[0099] The polyalkylene glycol (meth)acrylate is preferably at least one selected from the group consisting of polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, and polybutylene glycol (meth)acrylate, more preferably at least one selected from the group consisting of polyethylene glycol (meth)acrylate and polypropylene glycol (meth)acrylate, and even more preferably polyethylene glycol (meth)acrylate.

[0100] (Molecular Weight Control Agent) A molecular weight control agent may be used as a raw material for the polymer. The polymer may contain one type of structure derived from the molecular weight control agent alone, or may contain two or more types of structures derived from the molecular weight control agent.

[0101] The molecular weight control agent is an additive capable of suppressing polymerization and controlling the molecular weight range, and is typically a chain transfer agent. The molecular weight control agent is preferably an aromatic compound. Examples of the molecular weight control agent include various chain transfer agents, RAFT agents, NMP agents, ATRP agents, and TERP agents, and sulfur-containing chain transfer agents such as thiol-type chain transfer agents and RAFT agents are preferred. These may be used alone or in combination of two or more.

[0102] The thiol-type chain transfer agent may be a monothiol compound, a dithiol compound, a trithiol compound, or a polythiol compound having tetrathiol or more, but is preferably a monothiol compound or a dithiol compound. The thiol-type chain transfer agent may be a thiol compound having a sulfur atom in addition to the thiol group. The thiol compound may be a molecule consisting only of carbon, hydrogen, and sulfur. Specific examples of the thiol-type chain transfer agent include aliphatic monothiol compounds, aliphatic polythiol compounds, aliphatic thiols containing sulfur atoms in addition to mercapto groups, aromatic monothiol compounds, aromatic polythiols, aromatic polythiol compounds containing sulfur atoms in addition to mercapto groups, heterocyclic compounds containing sulfur atoms in addition to mercapto groups, compounds containing hydroxy groups in addition to mercapto groups, and derivatives thereof. Aromatic monothiol compounds or aromatic polythiol compounds containing sulfur atoms in addition to mercapto groups are preferred, and bis(4-mercaptophenyl)sulfide (4,4'-thiobisbenzenethiol) and 4-mercaptopyridine are more preferred. These may be used alone or in combination of two or more.

[0103] Examples of the aliphatic monothiol compound include methanethiol, ethanethiol, propanethiol, butanethiol, and cyclohexanethiol. Examples of aliphatic polythiol compounds include methanedithiol, 1,2-ethanedithiol, 1,1-propanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 2,2-propanedithiol, 1,6-hexanedithiol, 1,2,3-propanetrithiol, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2-methylcyclohexane-2,3-dithiol, 1,1-bis(mercaptomethyl)cyclohexane, thiomalic acid bis(2-mercaptoethyl ester), 2,3-dimercapto-1-propanol(2-mercaptoacetate), 2,3-dimercapto-1-propanol(3-mercaptopropionate), dimercapto-1-propanol(2-mercaptoacetate), di ... Examples of the mercaptosilane include ethylene glycol bis(2-mercaptoacetate), diethylene glycol bis(3-mercaptopropionate), 1,2-dimercaptopropyl methyl ether, 2,3-dimercaptopropyl methyl ether, 2,2-bis(mercaptomethyl)-1,3-propanedithiol, bis(2-mercaptoethyl)ether, ethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), trimethylolpropane bis(2-mercaptoacetate), trimethylolpropane bis(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(3-mercaptopropionate), and tetrakis(mercaptomethyl)methane.

[0104] Examples of aliphatic thiols containing a sulfur atom in addition to a mercapto group include bis(mercaptomethyl)sulfide, bis(mercaptoethyl)sulfide, bis(mercaptopropyl)sulfide, bis(mercaptomethylthio)methane, bis(2-mercaptoethylthio)methane, bis(3-mercaptopropyl)methane, 1,2-bis(mercaptomethylthio)ethane, 1,2-(2-mercaptoethylthio)ethane, 1,2-(3-mercaptopropyl)ethane, 1,3-bis(mercaptomethylthio)propane, 1,3-bis(2-mercaptoethylthio)propane, 1,3-bis(3-mercaptopropylthio)propane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, and 2-mercaptoethylthio-1,3-propanedithiol. , 1,2,3-tris(mercaptomethylthio)propane, 1,2,3-tris(2-mercaptoethylthio)propane, 1,2,3-tris(3-mercaptopropylthio)propane, tetrakis(mercaptomethylthiomethyl)methane, tetrakis(2-mercaptoethylthiomethyl)methane, tetrakis(3-mercaptopropylthiomethyl)methane, bis(2,3-dimercaptopropyl)sulfide, 2,5-dimercapto-1,4-dithiane, bis(mercaptomethyl)disulfide, bis(mercaptoethyl)disulfide, bis(mercaptopropyl)disulfide, 4-mercaptomethyl-3,6-dithiaoctane-1,8-dithiol, bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol, bis(1,3-dimercapto-2-propyl) sulfide, hydroxymethyl sulfide bis(2-mercaptoacetate), hydroxymethyl sulfide bis(3-mercaptopropionate), hydroxyethyl sulfide bis(2-mercaptoacetate), hydroxyethyl sulfide bis(3-mercaptopropionate), hydroxypropyl sulfide bis(2-mercaptoacetate), hydroxypropyl sulfide bis(3-mercaptopropionate), hydroxymethyl disulfide bis(2-mercaptoacetate), hydroxymethyl disulfide bis(3-mercaptopropionate), hydroxyethyl disulfide bis(2-mercaptoacetate), hydroxyethyl disulfide bis(3-mercaptopropionate), hydroxypropyl disulfide bis(2-mercaptoacetate), hydroxypropyl disulfide bis(3-mercaptopropionate), 2-mercaptoethyl ether bis(2-mercaptoethyl ether 2-mercaptoethyl ether bis(3-mercaptopropionate), 1,4-dithiane-2,5-diol bis(2-mercaptoacetate), 1,4-dithiane-2,5-diol bis(3-mercaptopropionate), thioglycolic acid bis(2-mercaptoethyl ester), thiodipropionic acid bis(2-mercaptoethyl ester), 4,4'-thiodibutyric acid bis(2-mercaptoethyl ester), dithiodiglycolic acid bis (2-mercaptoethyl ester), dithiodipropionic acid bis(2-mercaptoethyl ester), 4,4'-dithiodibutyric acid bis(2-mercaptoethyl ester), thiodiglycolic acid bis(2,3-dimercaptopropyl ester), thiodipropionic acid bis(2,3-dimercaptopropyl ester), dithiodiglycolic acid bis(2,3-dimercaptopropyl ester), dithiodipropionic acid (2,3-dimercaptopropyl ester), and the like.

[0105] Examples of aromatic monothiol compounds include benzenethiol, o-methyl-α-toluenethiol, o-toluenethiol, m-toluenethiol, p-toluenethiol, 1-naphthalenethiol, 2-naphthalenethiol, and 4-mercaptopyridine, with 4-mercaptopyridine being preferred. Examples of aromatic polythiols include 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, 1,2-bis(mercaptoethyl)benzene, 1,3-bis(mercaptoethyl)benzene, 1,4-bis(mercaptoethyl)benzene, 1,2,3-trimercaptobenzene, 1,2,4-trimercaptobenzene, 1,3,5-trimercaptobenzene, and 1,2,3-tris(mercaptomethyl)benzene. Examples include benzene, 1,2,4-tris(mercaptomethyl)benzene, 1,3,5-tris(mercaptomethyl)benzene, 1,2,3-tris(mercaptoethyl)benzene, 1,2,4-tris(mercaptoethyl)benzene, 1,3,5-tris(mercaptoethyl)benzene, 2,5-toluenedithiol, 3,4-toluenedithiol, 1,3-di(p-methoxyphenyl)propane-2,2-dithiol, 1,3-diphenylpropane-2,2-dithiol, phenylmethane-1,1-dithiol, and 2,4-di(p-mercaptophenyl)pentane.

[0106] Examples of aromatic polythiol compounds containing sulfur atoms in addition to mercapto groups include 1,2-bis(mercaptomethylenethio)benzene, 1,3-bis(mercaptomethylenethio)benzene, 1,4-bis(mercaptomethylenethio)benzene, 1,2-bis(mercaptoethylenethio)benzene, 1,3-bis(mercaptoethylenethio)benzene, 1,4-bis(mercaptoethylenethio)benzene, 1,2-bis(mercaptopropylenethio)benzene, 1,3-bis(mercaptopropylenethio)benzene, and 1,4-bis(mercaptopropylenethio). Benzene, 1,2-bis(mercaptoethylenethiomethylene)benzene, 1,3-bis(mercaptoethylenethiomethylene)benzene, 1,4-bis(mercaptoethylenethiomethylene)benzene, 1,2-bis(mercaptopropylenethiomethylene)benzene, 1,3-bis(mercaptopropylenethiomethylene)benzene, 1,4-bis(mercaptopropylenethiomethylene)benzene, bis(4-mercaptophenyl)sulfide (4,4'-thiobisbenzenethiol), bis(3-mercaptophenyl)sulfide, 4,4'-oxybisbenzene thiol, 4,4'-biphenyldithiol, 1,2-bis(mercaptomethyleneoxy)benzene, 1,3-bis(mercaptomethyleneoxy)benzene, 1,4-bis(mercaptomethyleneoxy)benzene, 1,2-bis(mercaptoethyleneoxy)benzene, 1,3-bis(mercaptoethyleneoxy)benzene, 1,4-bis(mercaptoethyleneoxy)benzene, 1,2-bis(mercaptoethyleneoxymethylene)benzene, 1,3-bis(mercaptoethyleneoxymethylene)benzene, 1,4-bis(mercaptoethyleneoxy)benzene methylene)benzene, 1,2-bis(mercaptopropyleneoxymethylene)benzene, 1,3-bis(mercaptopropyleneoxymethylene)benzene, 1,4-bis(mercaptopropyleneoxymethylene)benzene, 1,3,5-trimercaptobenzene, 1,2,3-tris(mercaptomethylthio)benzene, 1,2,4-tris(mercaptomethylthio)benzene, 1,3,5-tris(mercaptomethylthio)benzene, 1,2,3-tris(mercaptoethylthio)benzene, 1,2,4-tris(mercaptoethylthio)benzene, 1,3,5-tris(mercaptoethylthio)benzene, and bis(4-mercaptophenyl)sulfide (4,4'-thiobisbenzenethiol) is preferred.

[0107] Examples of heterocyclic compounds containing a sulfur atom in addition to a mercapto group include 3,4-thiophenedithiol and 2,5-dimercapto-1,3,4-thiadiazole. Examples of compounds containing a hydroxy group in addition to a mercapto group include 2-mercaptoethanol, 3-mercapto-1,2-propanediol, glycerin di(mercaptoacetate), 1-hydroxy-4-mercaptocyclohexane, 2,4-dimercaptophenol, 2-mercaptohydroquinone, 4-mercaptophenol, 3,4-dimercapto-2-propanol, 1,3-dimercapto-2-propanol, 2,3-dimercapto-1-propanol, and 1,2-dimercapto-1,3 -butanediol, pentaerythritol tris(3-mercaptopropionate), pentaerythritol mono(3-mercaptopropionate), pentaerythritol bis(3-mercaptopropionate), pentaerythritol tris(thioglycolate), dipentaerythritol pentakis(3-mercaptopropionate), hydroxymethyl-tris(mercaptoethylthiomethyl)methane, 1-hydroxyethylthio-3-mercaptoethylthiobenzene, and the like.

[0108] Specific examples of RAFT agents include dithioesters, trithiocarbonates, dithiocarbamates, and disulfides. These may be used alone or in combination of two or more. Examples of dithioesters include 2-cyano-2-propylbenzodithioate and 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid. Examples of trithiocarbonates include 2-cyano-2-propyldodecyltrithiocarbonate, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid, and cyanomethyldodecyltrithiocarbonate. Examples of dithiocarbamates include cyanomethylmethyl(phenyl)carbamodithioate. Examples of disulfides include bis(thiobenzoyl)disulfide and bis(dodecylsulfanylthiocarbonyl)disulfide.

[0109] (Polymer Composition) The content of the repeating unit derived from the iodine-containing monomer represented by formula (1B) in the polymer is preferably 1 to 100 mass %, more preferably 3 to 70 mass %, even more preferably 5 to 50 mass %, still more preferably 7 to 40 mass %, still more preferably 8 to 35 mass %, still more preferably 10 to 30 mass %, and even more preferably 15 to 25 mass %. By ensuring that the content of the repeating unit derived from the iodine-containing monomer represented by formula (1B) falls within the above range, the resolution and etching resistance of the positive resist composition can be improved, and the resist sensitivity characteristics can be improved, as well as the solvent solubility, heat resistance, and film-formability can be improved.

[0110] When the polymer contains a repeating unit derived from a phenolic hydroxyl group-containing monomer, the content of the repeating unit derived from the phenolic hydroxyl group-containing monomer in the polymer is preferably 1 to 80 mass %, more preferably 5 to 70 mass %, even more preferably 10 to 65 mass %, still more preferably 20 to 60 mass %, even more preferably 30 to 55 mass %, and still more preferably 40 to 50 mass %.

[0111] When the polymer contains repeating units derived from a phenolic hydroxyl group-containing monomer, the molar ratio of repeating units derived from the phenolic hydroxyl group-containing monomer to repeating units derived from the iodine-containing monomer represented by formula (1B) [phenolic hydroxyl group-containing monomer / iodine-containing monomer] is preferably 20 / 80 to 95 / 5, more preferably 30 / 70 to 90 / 10, even more preferably 40 / 60 to 90 / 10, still more preferably 50 / 50 to 85 / 15, even more preferably 60 / 40 to 80 / 20, and still more preferably 65 / 35 to 75 / 25. By setting the content of repeating units derived from the phenolic hydroxyl group-containing monomer within the above range, adhesion to the substrate and film-formability are improved.

[0112] When the polymer contains a repeating unit derived from an adamantane structure-containing monomer, the content of the repeating unit derived from the adamantane structure-containing monomer in the polymer is preferably 1 to 80 mass%, more preferably 3 to 70 mass%, even more preferably 5 to 60 mass%, still more preferably 10 to 50 mass%, still more preferably 20 to 45 mass%, and still more preferably 30 to 40 mass%.

[0113] When the polymer contains repeating units derived from an adamantane structure-containing monomer, the molar ratio of repeating units derived from the adamantane structure-containing monomer to repeating units derived from the iodine-containing monomer represented by Formula (1B) [adamantane structure-containing monomer / iodine-containing monomer] is preferably 20 / 80 to 99 / 1, more preferably 30 / 70 to 90 / 10, even more preferably 40 / 60 to 85 / 15, still more preferably 50 / 50 to 80 / 20, even more preferably 55 / 45 to 75 / 25, and still more preferably 60 / 40 to 70 / 30. By setting the content of repeating units derived from the adamantane structure-containing monomer within the above range, the polymer is easily decomposable by acid and developability is improved, making it possible to form fine patterns.

[0114] When the polymer contains a structure derived from a molecular weight control agent, the content of the structure derived from the molecular weight control agent in the polymer is preferably 1 to 80% by mass, more preferably 3 to 60% by mass, even more preferably 5 to 50% by mass, still more preferably 6 to 30% by mass, even more preferably 8 to 20% by mass, and still more preferably 10 to 20% by mass.

[0115] (Molecular Weight of Polymer) The number average molecular weight of the polymer is preferably 500 to 100,000, more preferably 1,000 to 50,000, even more preferably 2,000 to 50,000, still more preferably 3,000 to 40,000, still more preferably 5,000 to 35,000, still more preferably 10,000 to 30,000, and still more preferably 20,000 to 30,000. When the number average molecular weight of the polymer is within the above range, the solubility and film-forming properties of the polymer become excellent. The number average molecular weight is a polystyrene-equivalent molecular weight.

[0116] The molecular weight distribution (Mw / Mn) of the polymer is preferably 1.3 to 7.5, more preferably 1.5 to 7.0, even more preferably 2.0 to 6.0, still more preferably 2.5 to 5.0, and still more preferably 3.0 to 4.0.

[0117] <Method for Producing Polymer> There are no particular restrictions on the method for producing the polymer contained in the positive resist composition of the present invention, as long as it is a polymer that contains a repeating unit derived from the iodine-containing monomer represented by formula (1B). However, the following method is preferred.

[0118] The polymer can be obtained by polymerizing the above-mentioned monomers as raw materials. The polymerizing step may be a step of polymerizing the monomers in the presence of a molecular weight control agent. By polymerizing the monomers in the presence of a molecular weight control agent, the molecular weight can be controlled, and the resulting polymer can have a target molecular weight.

[0119] The polymerization method in the above step is not particularly limited. Examples of the polymerization method include bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc., with solution polymerization being preferred. Examples of the polymerization method include radical polymerization, anionic polymerization, and cationic polymerization, with radical polymerization being preferred. An appropriate polymerization method can be selected depending on the type of monomer, polymerization temperature, etc.

[0120] It is preferable to use a polymerization initiator in the polymerization in the above step. The polymerization initiator can be selected depending on the type of monomer, the polymerization temperature, etc. Examples of the polymerization initiator include azo initiators and peroxide initiators, with azo initiators being preferred. Examples of azo initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,2-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), and 2,2'-azobis(2-amidinopropane) dihydrochloride, with 2,2'-azobisisobutyronitrile being preferred. Examples of peroxide initiators include benzoyl peroxide, di-t-butyl hydroperoxide, t-butyl hydroperoxide, cumyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, benzoyl peroxide, dicumyl peroxide, ethyl 3,3-di(t-amylperoxy)butyrate, potassium sulfate, ammonium persulfate, etc. One type of polymerization initiator may be used alone, or two or more types may be used in combination.

[0121] The amount of the polymerization initiator used may be appropriately changed depending on the type of monomer and the type of polymerization initiator, but is preferably 0.1 to 50 mol %, more preferably 0.5 to 30 mol %, even more preferably 1 to 20 mol %, still more preferably 2 to 10 mol %, and still more preferably 3 to 7 mol %, based on the total amount of the monomers.

[0122] When the polymerization in the above step is carried out by solution polymerization, it is preferable to select an appropriate solvent taking into consideration the solubility of the monomer and polymerization initiator, the polymerization temperature, etc., and to carry out the polymerization in that solvent. A preferred solvent is one in which the resulting polymer is soluble. Examples of solvents used in the polymerization include N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone, acetone, THF, benzene, toluene, ethylbenzene, xylene, chlorobenzene, methyl ethyl ketone, ethyl lactate, isopropyl alcohol, and the like. These solvents may be used alone or in combination of two or more. Among these, amide solvents are more preferable, and N,N-dimethylformamide is even more preferable.

[0123] The amount of the raw material monomer used may be varied so as to obtain a polymer with the desired composition. Specifically, the following amounts are preferred. The amount of the iodine-containing monomer represented by Formula (1B) used is preferably 1 to 100% by mass, more preferably 3 to 70% by mass, even more preferably 5 to 50% by mass, still more preferably 7 to 40% by mass, even more preferably 8 to 35% by mass, still more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass, relative to the total amount of the monomer and the molecular weight control agent. By setting the amount of the iodine-containing monomer represented by Formula (1B) used within the above ranges, the resist sensitivity characteristics of the positive resist composition can be improved, and also the solvent solubility, heat resistance, and film-forming properties can be improved.

[0124] When the raw material monomer contains a phenolic hydroxyl group-containing monomer, the amount of the phenolic hydroxyl group-containing monomer used is preferably 1 to 80 mass %, more preferably 5 to 70 mass %, even more preferably 10 to 65 mass %, still more preferably 20 to 60 mass %, still more preferably 30 to 55 mass %, and even more preferably 40 to 50 mass %, based on the total amount of the monomer and the molecular weight control agent.

[0125] When the raw material monomer contains a phenolic hydroxyl group-containing monomer, the molar ratio of the phenolic hydroxyl group-containing monomer to the iodine-containing monomer represented by Formula (1B) [phenolic hydroxyl group-containing monomer / iodine-containing monomer] is preferably 20 / 80 to 95 / 5, more preferably 30 / 70 to 90 / 10, even more preferably 40 / 60 to 90 / 10, even more preferably 50 / 50 to 85 / 15, even more preferably 60 / 40 to 80 / 20, and even more preferably 65 / 35 to 75 / 25. By using the phenolic hydroxyl group-containing monomer in an amount within the above range, adhesion to the substrate is improved, and film-forming properties are improved. Furthermore, because the phenolic hydroxyl group can affect the polymerization reaction, it is preferable to use a monomer in which the phenolic hydroxyl group is protected as the phenolic hydroxyl group-containing monomer. Examples of the protecting group in the monomer in which the phenolic hydroxyl group is protected include a benzyl group, a methoxymethyl group, a trialkylsilyl group, an acyl group, a benzoyl group, a trityl group, etc., and preferably an acyl group, and more preferably an acetyl group. The protecting group is preferably deprotected after polymerization to introduce a repeating unit derived from the phenolic hydroxyl group-containing monomer.

[0126] When the raw material monomer contains an adamantane structure-containing monomer, the molar ratio of the adamantane structure-containing monomer to the iodine-containing monomer represented by formula (1B) [adamantane structure-containing monomer / iodine-containing monomer] is preferably 20 / 80 to 99 / 1, more preferably 30 / 70 to 90 / 10, even more preferably 40 / 60 to 85 / 15, still more preferably 50 / 50 to 80 / 20, still more preferably 55 / 45 to 75 / 25, and still more preferably 60 / 40 to 70 / 30. By using an amount of the adamantane structure-containing monomer within the above range, the monomer is easily decomposed by acid and developability is improved, making it possible to form a fine pattern.

[0127] When a molecular weight control agent is used as a raw material, the amount of the molecular weight control agent used is preferably 1 to 80 mass %, more preferably 3 to 60 mass %, even more preferably 5 to 50 mass %, still more preferably 6 to 30 mass %, still more preferably 8 to 20 mass %, and even more preferably 10 to 20 mass %, based on the total amount of the monomer and the molecular weight control agent.

[0128] The reaction temperature may be adjusted appropriately depending on the decomposition temperature of the polymerization initiator used, but is preferably 0 to 100° C., more preferably 20 to 80° C., even more preferably 30 to 70° C., still more preferably 40 to 70° C., and even more preferably 50 to 70° C. The reaction time may be adjusted appropriately depending on the reaction temperature, amount of catalyst, reactivity of raw materials, target molecular weight, and the like, but is preferably 1 to 72 hours, more preferably 5 to 60 hours, even more preferably 12 to 50 hours, still more preferably 15 to 40 hours, and even more preferably 15 to 30 hours.

[0129] When the polymer after polymerization has a protecting group, it is preferable to carry out a deprotection step. The deprotection step may be carried out according to the type of protecting group, and a known method may be applied. For example, when a monomer in which the phenolic hydroxyl group of a phenolic hydroxyl group-containing monomer is protected with an acyl group is used, it is preferable to deprotect the acyl group by hydrolysis to impart a phenolic hydroxyl group to the polymer.

[0130] The obtained polymer is preferably purified by a conventional post-treatment. Specifically, it is preferable to remove raw materials and by-products by pouring the reaction mixture into an organic solvent in which the polymer is insoluble and recovering the target polymer as a precipitate. Alternatively, it is preferable to dissolve the polymer in an organic solvent in which the polymer is soluble and wash with water or the like to remove the catalyst and the like. If the polymer is obtained as a solution in an organic solvent at the end of the reaction or purification treatment, it is preferable to concentrate and dry the polymer to obtain a solid. The polymer obtained in this manner has high solubility in solvents, excellent film-forming properties, and excellent resist sensitivity characteristics.

[0131] <Composition of Positive Resist Composition> The positive resist composition of the present invention is a lithography film-forming composition that contains the above-described polymer. That is, the positive resist composition of the present invention is a lithography film-forming composition that contains a polymer that contains a repeating unit derived from an iodine-containing monomer represented by formula (1B). The positive resist composition of the present invention contains the polymer that has excellent solvent solubility, heat resistance, and film-forming properties, and has excellent resist sensitivity characteristics, making it suitable as a composition for forming a resist film. That is, the positive resist composition of the present invention is preferably a resist film-forming composition.

[0132] <Solvent> As long as the positive resist composition of the present invention contains the above-mentioned polymer, the formulation may be adjusted appropriately depending on the application, but it is preferable that the composition further contains a solvent as a component other than the above-mentioned polymer.

[0133] The solvent is not particularly limited, but examples thereof include ethylene glycol monoalkyl ether acetates, ethylene glycol monoalkyl ethers, propylene glycol monoalkyl ether acetates, propylene glycol monoalkyl ethers, lactate esters, aliphatic carboxylic acid esters, esters other than the above esters, aromatic hydrocarbons, ketones, amides, lactones, and ethers, and is preferably at least one selected from the group consisting of propylene glycol monoalkyl ether acetates, propylene glycol monoalkyl ethers, lactate esters, aliphatic carboxylic acid esters, ketones, and ethers, and more preferably at least one selected from the group consisting of propylene glycol monoalkyl ether acetates, propylene glycol monoalkyl ethers, and ketones.

[0134] Examples of ethylene glycol monoalkyl ether acetates include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, and ethylene glycol mono-n-butyl ether acetate. Examples of ethylene glycol monoalkyl ethers include ethylene glycol monomethyl ether and ethylene glycol monoethyl ether. Examples of propylene glycol monoalkyl ether acetates include propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate (PGMEA), propylene glycol mono-n-propyl ether acetate, and propylene glycol mono-n-butyl ether acetate, with propylene glycol monoethyl ether acetate (PGMEA) being preferred. Examples of propylene glycol monoalkyl ethers include propylene glycol monomethyl ether (PGME) and propylene glycol monoethyl ether, with propylene glycol monomethyl ether (PGME) being preferred.

[0135] Examples of lactic acid esters include methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, and n-amyl lactate, with ethyl lactate being preferred. Examples of aliphatic carboxylic acid esters include methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, n-amyl acetate, n-hexyl acetate, methyl propionate, and ethyl propionate, with butyl acetate and ethyl propionate being preferred. Examples of esters other than the above esters include methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl 3-methoxy-2-methylpropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, butyl 3-methoxy-3-methylpropionate, butyl 3-methoxy-3-methylbutyrate, methyl acetoacetate, methyl pyruvate, ethyl pyruvate, and methyl 2-hydroxyisobutyrate (HBM). Examples of aromatic hydrocarbons include toluene and xylene. Examples of ketones include methyl ethyl ketone, 2-heptanone, 3-heptanone, 4-heptanone, cyclopentanone (CPN), cyclohexanone (CHN), and the like, with 2-heptanone, cyclopentanone (CPN), and cyclohexanone (CHN) being preferred. Examples of amides include N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpyrrolidone. Examples of lactones include γ-lactone. Examples of ethers include anisole. One solvent may be used alone, or two or more solvents may be used in combination.

[0136] The solvent is preferably a safe solvent, and is preferably at least one selected from the group consisting of propylene glycol monoethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), cyclopentanone (CPN), cyclohexanone (CHN), 2-heptanone, anisole, butyl acetate, ethyl propionate, and ethyl lactate, and more preferably at least one selected from the group consisting of propylene glycol monoethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and cyclohexanone (CHN).

[0137] The content of the solvent is preferably from 20 to 99 mass %, more preferably from 50 to 99 mass %, even more preferably from 60 to 98 mass %, and still more preferably from 90 to 98 mass %, relative to the total amount of the positive resist composition.

[0138] <Other Components> As long as the positive resist composition of the present invention contains the above-mentioned polymer, the formulation may be adjusted appropriately depending on the application, but the positive resist composition may also contain components other than the above-mentioned polymer and other than the solvent. The following components are solid components, and in the positive resist composition they are usually dissolved in a solvent and formulated.

[0139] The positive resist composition of the present invention may further include, as other components, at least one selected from the group consisting of an acid generator, a crosslinking agent, an acid diffusion controller, and other additives; preferably, it further includes at least one selected from the group consisting of an acid generator, a crosslinking agent, and an acid diffusion controller; even more preferably, it further includes at least one selected from the group consisting of an acid generator and a crosslinking agent; and even more preferably, it further includes an acid generator and a crosslinking agent.

[0140] The content of the polymer contained in the positive resist composition of the present invention is preferably 50 to 99.4 mass %, more preferably 60 to 95 mass %, even more preferably 70 to 90 mass %, and still more preferably 70 to 85 mass %, relative to the total content of the solid components (the total content of the polymer, acid generator, crosslinking agent, acid diffusion controller, and other additives). Within this range, it is possible to improve resolution and reduce line edge roughness (LER).

[0141] (Acid Generator) The positive resist composition of the present invention may further contain an acid generator, and preferably further contains an acid generator.

[0142] The acid generator is preferably an acid generator that generates an acid directly or indirectly upon irradiation with any one of visible light, ultraviolet light, excimer laser, electron beam, extreme ultraviolet light (EUV), X-ray, and ion beam. As the radiation, ultraviolet light such as g-ray or i-ray may be used, and the use of an excimer laser is preferred because it enables microfabrication. Furthermore, the use of an electron beam, extreme ultraviolet light, X-ray, or ion beam as the high-energy beam is also preferred because it enables microfabrication.

[0143] Examples of the acid generator include compounds disclosed in WO 2017 / 033943. The acid generator is preferably an acid generator having an aromatic ring, and more preferably an acid generator having a sulfonate ion with an aryl group. The acid generator is more preferably at least one selected from the group consisting of diphenyltrimethylphenylsulfonium p-toluenesulfonate, triphenylsulfonium p-toluenesulfonate, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoromethanesulfonate, ditertiarybutyldiphenyliodonium nonafluorobutanesulfonate, and pyridinium p-toluenesulfonate. Use of such an acid generator can reduce line edge roughness.

[0144] The acid generator may preferably further contain a diazonaphthoquinone photoactive compound. The diazonaphthoquinone photoactive compound is not particularly limited as long as it is a compound generally used as a photosensitive component in positive resist compositions. The diazonaphthoquinone photoactive compound is preferably a polymeric diazonaphthoquinone photoactive compound or a non-polymeric diazonaphthoquinone photoactive compound, more preferably a non-polymeric diazonaphthoquinone photoactive compound, even more preferably a non-polymeric diazonaphthoquinone photoactive compound having a molecular weight of 1,500 or less, even more preferably a non-polymeric diazonaphthoquinone photoactive compound having a molecular weight of 1,200 or less, and even more preferably a non-polymeric diazonaphthoquinone photoactive compound having a molecular weight of 1,000 or less. Specific examples of diazonaphthoquinone photoactive compounds include the non-polymeric diazonaphthoquinone photoactive compounds disclosed in WO 2016 / 158881. The diazonaphthoquinone photoactive compounds can be used alone or in combination of two or more.

[0145] The content of the acid generator contained in the positive resist composition of the present invention is preferably 0.001 to 49 mass %, more preferably 1 to 40 mass %, even more preferably 3 to 30 mass %, and still more preferably 10 to 25 mass %, relative to the total content of the solid components (the total content of the polymer, acid generator, crosslinking agent, acid diffusion controller, and other additives). Within this range, sensitivity can be increased and edge roughness of the pattern profile can be reduced. The acid generators can be used alone or in combination of two or more types.

[0146] (Crosslinking Agent) The positive resist composition of the present invention may further contain a crosslinking agent, and preferably further contains a crosslinking agent. The crosslinking agent contained in the positive resist composition of the present invention is preferably an acid crosslinking agent. The acid crosslinking agent can crosslink the polymer intramolecularly or intermolecularly by the acid generated from the acid generator. By containing a crosslinking agent, the strength of the pattern can be increased.

[0147] The acid crosslinking agent is preferably a compound having a crosslinkable group. Examples of the crosslinkable group include, but are not limited to, a hydroxyalkyl group, a carbonyl group, a nitrogen-containing group, a glycidyl-containing group, an aromatic group, a polymerizable multiple bond-containing group, and groups derived therefrom. Hydroxyalkyl groups and groups derived therefrom are preferred. Specifically, hydroxyalkyl groups and groups derived therefrom include hydroxyalkyl groups, alkoxyalkyl groups, and acetoxyalkyl groups. Preferably, at least one group selected from the group consisting of hydroxyalkyl groups and alkoxyalkyl groups is used, and more preferably, an alkoxymethyl group. Examples of carbonyl groups and groups derived therefrom include formyl groups and carboxyalkyl groups. Examples of nitrogen-containing groups include dimethylaminomethyl groups, diethylaminomethyl groups, dimethylolaminomethyl groups, diethylolaminomethyl groups, and morpholinomethyl groups. Examples of glycidyl-containing groups include glycidyl ether groups, glycidyl ester groups, and glycidylamino groups. Examples of aromatic groups include benzyloxymethyl groups, benzoyloxymethyl groups, allyloxyalkyl groups, and aralkyloxyalkyl groups. Examples of the polymerizable multiple bond-containing group include a vinyl group and an isopropenyl group. Suitable examples of the acid crosslinking agent are listed below, divided into several categories. The type and content of the acid crosslinking agent may be adjusted depending on the type of substrate used when forming the resist pattern.

[0148] Preferred examples of the acid crosslinking agent include methylol group-containing compounds, alkoxyalkyl group-containing compounds, carboxymethyl group-containing compounds, and epoxy compounds. Examples of methylol group-containing compounds include methylol group-containing melamine compounds, methylol group-containing benzoguanamine compounds, methylol group-containing urea compounds, methylol group-containing glycoluril compounds, and methylol group-containing phenolic compounds. Examples of alkoxyalkyl group-containing compounds include alkoxyalkyl group-containing melamine compounds, alkoxyalkyl group-containing benzoguanamine compounds, alkoxyalkyl group-containing urea compounds, alkoxyalkyl group-containing glycoluril compounds, and alkoxyalkyl group-containing phenolic compounds. Examples of carboxymethyl group-containing compounds include carboxymethyl group-containing melamine compounds, carboxymethyl group-containing benzoguanamine compounds, carboxymethyl group-containing urea compounds, carboxymethyl group-containing glycoluril compounds, and carboxymethyl group-containing phenolic compounds. Examples of epoxy compounds include bisphenol A-based epoxy compounds, bisphenol F-based epoxy compounds, bisphenol S-based epoxy compounds, novolac resin-based epoxy compounds, resole resin-based epoxy compounds, and poly(hydroxystyrene)-based epoxy compounds.

[0149] Further examples of the acid crosslinking agent include a compound obtained by introducing the crosslinkable group into an acidic functional group in a compound having a phenolic hydroxyl group to impart crosslinkability, and a resin obtained by introducing the crosslinkable group into an acidic functional group in an alkali-soluble resin to impart crosslinkability. The introduction rate of the crosslinkable group is preferably 0 to 80 mol %, more preferably 0 to 60 mol %, and even more preferably 0 to 40 mol %, based on the total acidic functional groups in the compound having a phenolic hydroxyl group and the alkali-soluble resin. This range is preferable because it allows the crosslinking reaction to occur at an appropriate rate, thereby avoiding a decrease in the residual film rate and problems such as swelling and meandering of the pattern.

[0150] Further examples of the acid crosslinking agent include alkoxyalkylated urea compounds or resins thereof, alkoxyalkylated glycoluril compounds or resins thereof, phenol derivatives, and compounds having an α-hydroxyisopropyl group. Examples of these compounds or resins include the compounds disclosed in International Publication No. 2017 / 033943. The phenol derivative is a phenol derivative having one to six benzene rings in the molecule and two or more hydroxyalkyl groups or alkoxyalkyl groups throughout the molecule, with the hydroxyalkyl groups or alkoxyalkyl groups bonded to any of the benzene rings.

[0151] The content of the crosslinking agent contained in the positive resist composition of the present invention is preferably 0 to 49 mass %, more preferably 0 to 40 mass %, even more preferably 0 to 30 mass %, and still more preferably 0 to 20 mass %, relative to the total content of the solid components (the total content of the polymer, acid generator, crosslinking agent, acid diffusion controller, and other additives). This range is preferable because it is possible to suppress dissolution of the resist film in a developer, suppress a decrease in the residual film rate and swelling / whirling of the resist pattern, and also improve the heat resistance of the resist.

[0152] (Acid Diffusion Controller) The positive resist composition of the present invention may further contain an acid diffusion controller, and preferably further contains an acid diffusion controller. The acid diffusion controller optionally contained in the positive resist composition of the present invention controls the diffusion of the acid generated from the acid generator upon irradiation within the resist film, thereby preventing undesirable chemical reactions in unexposed regions. This improves the storage stability of the positive resist composition, allowing for improved resolution. Furthermore, it is possible to suppress changes in the line width of the resist pattern due to variations in the exposure time before and after radiation exposure, resulting in extremely excellent process stability.

[0153] Examples of the acid diffusion controller include radiolytic basic compounds such as nitrogen atom-containing basic compounds, basic sulfonium compounds, and basic iodonium compounds. Examples of the acid diffusion controller include the compounds disclosed in WO 2017 / 033943. The acid diffusion controller can be used alone or in combination of two or more.

[0154] The content of the acid diffusion controller contained in the positive resist composition of the present invention is preferably 0.001 to 49% by mass relative to the total content of the solid components (the total content of the polymer, acid generator, crosslinking agent, acid diffusion controller, and other additives). From the viewpoint of preventing a decrease in sensitivity and developability of unexposed areas, the content is more preferably 0.01 to 10% by mass, even more preferably 0.01 to 5% by mass, and even more preferably 0.01 to 3% by mass. Within this range, a decrease in resolution and deterioration of the shape and dimensional fidelity of the resist pattern can be suppressed. Furthermore, deterioration of the shape of the upper layer of the resist pattern does not occur when a long waiting time is required between electron beam irradiation and post-irradiation baking.

[0155] (Other Additives) The positive resist composition of the present invention may further contain other additives, as long as the effects of the present invention are not impaired. Examples of other additives include a dissolution promoter, a dissolution controller, a sensitizer, a surfactant, and an organic carboxylic acid or a phosphorus oxoacid or a derivative thereof. Examples of other additives include the compounds disclosed in WO 2017 / 033943. The total content of other additives contained in the positive resist composition of the present invention is preferably 0 to 49 mass%, more preferably 0 to 5 mass%, even more preferably 0 to 1 mass%, still more preferably 0 mass%, and even more preferably 0 mass%, relative to the total content of the solid components (the total content of the polymer, acid generator, crosslinker, acid diffusion controller, and other additives). It is even more preferable that the positive resist composition does not contain any other additives.

[0156] <Method for Producing Positive Resist Composition> There are no particular limitations on the method for producing the positive resist composition of the present invention, but a preferred method is to dissolve the components in a solvent to form a homogeneous solution. If necessary, the solution obtained above may be filtered to remove impurities. The filter used for filtration preferably has a pore size of about 0.2 μm.

[0157] The positive resist composition of the present invention may contain a resin, as long as the effects of the present invention are not impaired. Examples of resins include novolak resins, polyvinylphenols, polyacrylic acid, polyvinyl alcohol, and styrene-maleic anhydride resins. The total content of resins contained in the positive resist composition of the present invention is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 5 parts by mass or less, still more preferably 0 parts by mass, and even more preferably zero parts by mass, relative to 100 parts by mass of the polymer.

[0158] [Resist Film] The resist film of the present invention is a resist film formed from the positive resist composition. As described above, the positive resist composition is a positive resist composition that contains a polymer containing a repeating unit derived from an iodine-containing monomer represented by formula (1B). Therefore, it has excellent resolution, etching resistance, and resist sensitivity characteristics, making it an excellent raw material for forming a resist film. The resist film of the present invention can be formed from the positive resist composition by the method described below in the method for forming a resist pattern.

[0159] The resist film of the present invention can be obtained as an amorphous film by known methods such as spin coating, and a positive resist pattern can be obtained depending on the type of developer used.

[0160] When a positive resist pattern is to be formed, the dissolution rate of the amorphous film formed by spin-coating the positive resist composition in a developer at 23°C is preferably 5 Å / sec or less, more preferably 0.0005 to 5 Å / sec. A dissolution rate within this range allows for a resist that is insoluble in the developer, thereby improving resolution. This is presumably because the change in solubility of the polymer containing a repeating unit derived from the iodine-containing monomer represented by formula (1B) before and after exposure increases the contrast at the interface between the exposed area that dissolves in the developer and the unexposed area that does not dissolve in the developer. Furthermore, the composition is effective in reducing line edge roughness and defects.

[0161] When forming a positive resist pattern, the dissolution rate in a developer at 23°C of the portion of the amorphous film formed by spin-coating the positive resist composition and exposed to radiation such as an excimer laser (preferably a KrF excimer laser), extreme ultraviolet light, an electron beam, or an X-ray is preferably 10 Å / sec or higher. A dissolution rate within this range is suitable for the resist and improves resolution. This is presumably because the micro-surface portion of the polymer containing a repeating unit derived from the iodine-containing monomer represented by formula (1B) dissolves, reducing line edge roughness. The composition also has the effect of reducing defects.

[0162] [Method of Forming a Resist Pattern] The method of forming a resist pattern of the present invention is a method of forming a resist pattern on a substrate using the positive resist composition. More specifically, it is a method of forming a resist pattern including the steps of forming a resist film on a substrate using the positive resist composition, and exposing and developing the resist film. The formed resist pattern can also be used as an upper layer resist in a multi-layer process.

[0163] <Step of Forming a Resist Film> The resist pattern forming method of the present invention includes a step of forming a resist film on a substrate using the positive resist composition. Examples of methods for forming a resist film include coating the positive resist composition on a substrate by a coating method such as spin coating, casting coating, or roll coating. Conventional substrates can be used as the substrate, including substrates for electronic components and substrates with a wiring pattern formed thereon. Examples of substrates include silicon wafers, substrates made of metals such as copper, chromium, iron, and aluminum, and glass substrates. Examples of materials for the wiring pattern include copper, aluminum, nickel, and gold. The substrate may also have an inorganic or organic film formed thereon. Examples of inorganic films include inorganic antireflective films (inorganic BARC). Examples of organic films include organic antireflective films (organic BARC). The substrate may also be surface-treated with hexamethyldisilazane (1,1,1,3,3,3-hexamethyldisilazane) or the like.

[0164] The substrate coated with the positive resist composition may be heated. The heating conditions may be adjusted as appropriate depending on the components of the composition, but heating to a temperature of preferably 20 to 250°C, more preferably 20 to 150°C, is preferred because this improves the adhesion of the resist film to the substrate.

[0165] <Exposure Step> The method for forming a resist pattern of the present invention includes a step of exposing the formed resist film. In this step, the resist film is exposed to light in a desired pattern. The exposure is carried out with a type of radiation selected from the group consisting of visible light, ultraviolet light, excimer laser, electron beam, extreme ultraviolet light (EUV), X-rays, and ion beam. The exposure conditions may be adjusted appropriately depending on the formulation of the lithography film-forming composition.

[0166] It is preferable to heat the substrate having the resist film after irradiation. The heating conditions may be appropriately adjusted depending on the formulation of the composition for forming a lithography film, but are preferably 20 to 250° C., more preferably 20 to 150° C. Heating allows a highly accurate fine pattern to be stably formed by exposure.

[0167] <Developing Step> The method for forming a resist pattern of the present invention includes a step of exposing the formed resist film to light and developing it. This step is a step of developing the exposed resist film with a developer. By this step, a desired resist pattern is formed.

[0168] The developer is preferably an alkaline aqueous solution. Different resist patterns can be produced depending on the type of developer. In general, a positive resist pattern can be obtained using an alkaline aqueous solution. A tetramethylammonium hydroxide aqueous solution is preferred as the alkaline aqueous solution. Examples of the developer include those disclosed in International Publication No. 2017 / 033943.

[0169] The developer may contain a surfactant. Examples of the surfactant include nonionic surfactants and ionic surfactants, and a nonionic surfactant is preferred. The surfactant is preferably at least one selected from the group consisting of fluorine-based surfactants and silicone-based surfactants, and more preferably at least one selected from the group consisting of nonionic fluorine-based surfactants and nonionic silicone-based surfactants. Examples of fluorine-based surfactants and silicone-based surfactants include those described in JP-A-62-36663, JP-A-61-226746, JP-A-61-226745, JP-A-62-170950, JP-A-63-34540, JP-A-7-230165, JP-A-8-62834, JP-A-9-54432, JP-A-9-5988, U.S. Pat. Nos. 5,405,720, 5,360,692, 5,529,881, 5,296,330, 5,436,098, 5,576,143, 5,294,511, and 5,824,451.

[0170] The amount of the surfactant used is preferably from 0.001 to 5% by mass, more preferably from 0.005 to 2% by mass, and even more preferably from 0.01 to 0.5% by mass, based on the total amount of the developer.

[0171] Examples of development methods include the dipping method, the puddle method, the spray method, and the dynamic dispensing method. The dipping method is a method in which a substrate is immersed in a tank filled with a developer for a certain period of time. The puddle method is a method in which the developer is piled up on the surface of the substrate by surface tension and left to stand for a certain period of time to develop. The spray method is a method in which the developer is sprayed onto the surface of the substrate. The dynamic dispensing method is a method in which the developer is continuously dispensed onto a substrate rotating at a constant speed while a developer dispensing nozzle is scanned at a constant speed. The development time is not particularly limited, but is preferably 10 to 90 seconds.

[0172] <Other Steps> The method of forming a resist pattern of the present invention may include the following steps in addition to the steps described above.

[0173] After the development step, a step of stopping the development while replacing the solvent with another solvent may be carried out.

[0174] It is preferable to include a step of washing with a rinse liquid (rinsing step) after the development step. The rinse liquid is preferably a solvent that does not dissolve the resist pattern, more preferably a solution containing an organic solvent or water. The rinse liquid is preferably a hydrophilic organic solvent or water, more preferably water. A plurality of organic solvents may be mixed.

[0175] The rinse liquid may contain a surfactant. The vapor pressure of the rinse liquid at 20°C is preferably 0.05 to 5 kPa, more preferably 0.1 to 5 kPa, and even more preferably 0.12 to 3 kPa. When the vapor pressure of the rinse liquid is within the above range, the temperature uniformity within the wafer surface is further improved, and further swelling due to penetration of the rinse liquid is further suppressed, thereby improving the dimensional uniformity within the wafer surface.

[0176] The cleaning method is preferably a spin coating method, a dipping method, or a spray method, and more preferably a spin coating method. It is more preferable to perform cleaning by a spin coating method, and then rotate the substrate at a rotation speed of 2000 rpm to 4000 rpm after cleaning to remove the rinse solution from the substrate. The spin coating method is a method in which the rinse solution is continuously applied onto a substrate rotating at a constant speed, the dipping method is a method in which the substrate is immersed in a tank filled with the rinse solution for a certain period of time, and the spray method is a method in which the rinse solution is sprayed onto the substrate surface. There are no particular limitations on the time for rinsing the pattern, but it is preferably 10 to 90 seconds.

[0177] After forming the resist pattern, a patterned wiring substrate can be obtained by etching, which can be performed by a known method such as dry etching using plasma gas or wet etching using an alkaline solution, cupric chloride solution, ferric chloride solution, or the like.

[0178] After forming the resist pattern, plating may be performed. The plating method is not particularly limited, but examples thereof include copper plating, solder plating, nickel plating, and gold plating.

[0179] The remaining resist pattern after etching can be stripped using an organic solvent. Examples of the organic solvent include, but are not limited to, PGMEA (propylene glycol monomethyl ether acetate), PGME (propylene glycol monomethyl ether), and ethyl lactate. Examples of the stripping method include, but are not limited to, a dipping method and a spray method. The wiring substrate on which the resist pattern is formed may be a multilayer wiring substrate and may have small-diameter through-holes. The wiring substrate may be formed by a lift-off method. The lift-off method is a method in which a resist pattern is formed, a metal is vapor-deposited in a vacuum, and then the resist pattern is dissolved in a solution.

[0180] The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples.

[0181] [1] Examples Related to Lithography Underlayer Film-Forming Composition (First Invention) [Analysis] Fourier transform infrared spectroscopy (FT-IR) spectra were measured using a JASCO FT / IR4200 (manufactured by JASCO Corporation). 1 H NMR spectrum, 13 C NMR spectra were measured using an FTECS-400K (manufactured by JEOL Ltd.) at a frequency of 400 MHz, using DMSO-d as the solvent and MeSi(TMS) as the internal standard. The number-average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the polymer were measured by size exclusion chromatography (SEC) under the following conditions. Standard polystyrene (narrow molecular weight distribution) was used for calibration. (Measurement conditions: Apparatus: HLC-8220 SEC apparatus, manufactured by Tosoh Corporation; Columns: TSKgel Super AW3000, AW2500 x 2; Detection: RI, UV; Eluent: DMF (20 mM) solution of LiBr and phosphoric acid; Flow rate: 0.6 mL / min)

[0182] [Evaluation] <Solubility> At 23°C, the polymers obtained in Production Examples 1A to 10A were dissolved in propylene glycol monomethyl ether acetate (PGMEA) and 1-methoxy-2-propanol (propylene glycol monomethyl ether, PGME) to give 30% by mass solutions. The solutions were then left to stand at -20°C for 30 days, and the solubility was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1A. (Evaluation criteria) A: It was confirmed by visual observation that no precipitates had formed. C: The formation of precipitates was confirmed by visual observation.

[0183] <Film Formability> The lithography underlayer film-forming compositions obtained in the Examples and Comparative Examples were applied to a silicon wafer by spin coating and dried to form a resist film with a thickness of 10 nm. Regarding film formability, compositions that could form the above resist film were rated as "good." The evaluation results are shown in Table 2A.

[0184] <EB Pattern Evaluation> The lithography underlayer film-forming composition obtained in the example was applied to a 300 nm thick SiO2 substrate and baked at 150°C for 60 seconds and then at 400°C for 120 seconds to form an underlayer film with a thickness of 70 nm. An ArF resist solution was applied to this underlayer film and baked at 130°C for 60 seconds to form a photoresist layer with a thickness of 140 nm. The ArF resist solution used was prepared by blending 5 parts by weight of a compound represented by the following formula (5), 1 part by weight of triphenylsulfonium nonafluorobutanesulfonate, 2 parts by weight of tributylamine, and 92 parts by weight of PGMEA. The compound represented by the following formula (5) was obtained as follows. 4.15 g of 2-methyl-2-methacryloyloxyadamantane, 3.00 g of methacryloyloxy-γ-butyrolactone, 2.08 g of 3-hydroxy-1-adamantyl methacrylate, and 0.38 g of 2,2'-azobis(isobutyronitrile) were dissolved in 80 mL of tetrahydrofuran to form a reaction solution. This reaction solution was polymerized for 22 hours under a nitrogen atmosphere at a reaction temperature of 63°C, and then the reaction solution was added dropwise to 400 mL of n-hexane. The resin thus produced was coagulated and purified, and the resulting white powder was filtered and dried overnight at 40°C under reduced pressure to obtain a compound represented by formula (5). The numbers in formula (5) indicate the ratio of each structural unit.

[0185]

[0186] Next, the photoresist layer was exposed to light using an electron beam lithography system (ELS-7500, 50 keV, manufactured by Elionix), baked at 115°C for 90 seconds (PEB), and developed with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) for 60 seconds, thereby obtaining a positive resist pattern.

[0187] The resist pattern shapes after development were inspected for defects in the resulting resist patterns with line widths of 55 nm L / S (1:1) and 80 nm L / S (1:1). The results are shown in Table 3A. In the table, "Good" indicates that no significant defects were observed in the resist patterns formed at line widths of 55 nm L / S (1:1) and 80 nm L / S (1:1) after development, and "Bad" indicates that significant defects were observed in the resist patterns formed at either line width. Furthermore, in the table, "Resolution" indicates the minimum line width at which no pattern collapse occurs and good rectangularity is obtained, and "Sensitivity" indicates the minimum electron beam energy required to draw a good pattern shape. As a comparative example, no underlayer film was formed, and the resolution, sensitivity, and resist pattern shape were evaluated in the same manner as in the previous examples. In Comparative Example 3, a photoresist layer was formed directly on a SiO2 substrate, and a positive resist pattern was obtained in the same manner as in the examples, except that no underlayer film was formed.

[0188] <EUV Exposure Evaluation> (EUV Sensitivity Evaluation) The lithography underlayer film-forming compositions obtained in the Examples and Comparative Examples were spin-coated onto a silicon wafer and then baked at 110°C for 60 seconds to form a photoresist layer with a thickness of 100 nm. Then, the wafer was irradiated with 1 mJ / cm using an extreme ultraviolet (EUV) exposure device "EUVES-7000" (product name, manufactured by LithoTech Japan Co., Ltd.). ２ to 1 mJ / cm ２ 80 mJ / cm ２ After maskless shot exposure with the exposure dose increased to 1000 ppm, the wafer was baked (PEB) at 110°C for 90 seconds and developed with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution for 60 seconds, yielding a wafer with 80 shots of exposure on the wafer. For each of the resulting shot exposure areas, the film thickness was measured using an optical interference film thickness meter "VM3200" (product name, manufactured by SCREEN Semiconductor Solutions Co., Ltd.), profile data of the film thickness versus exposure dose was obtained, and the exposure dose at which the slope of the film thickness variation versus exposure dose was greatest was determined as the sensitivity value (mJ / cm). ２) and used as an index of EUV sensitivity. EUV sensitivity was evaluated according to the following criteria. The lower the sensitivity value, the better the EUV sensitivity, and therefore it is preferable. The lower the sensitivity value, the higher the ability to supply secondary electrons and protons to the resist, particularly when used as an underlayer film, and therefore it is preferable. The evaluation results are shown in Table 4A. (Evaluation criteria) A: 30 mJ / cm ２ Less than B: 30 mJ / cm ２ More than 40mJ / cm ２ Less than C: 40 mJ / cm ２ End

[0189] [Raw Materials] The raw materials used in the examples and their abbreviations are as follows. 2,4,6-Triiodophenol (TIP) (manufactured by Tokyo Chemical Industry Co., Ltd.) Acryloyl chloride (AC) (manufactured by Tokyo Chemical Industry Co., Ltd.) 4-Mercaptopyridine (MP) (manufactured by Tokyo Chemical Industry Co., Ltd.) 4,4'-Thiobisbenzenethiol (TBBT) (manufactured by Tokyo Chemical Industry Co., Ltd.) 2-(2-ethoxyethoxy)ethyl acrylate (EEA) (manufactured by Tokyo Chemical Industry Co., Ltd.; dried over calcium hydride and purified by distillation) 2-Hydroxyethyl acrylate (HEA) (manufactured by Tokyo Chemical Industry Co., Ltd.; dried over calcium hydride and purified by distillation) Glycidyl methacrylate (GMA) (manufactured by Tokyo Chemical Industry Co., Ltd.; dried over calcium hydride and purified by distillation) 2,2'-Azobis(isobutyronitrile) (AIBN) (manufactured by Tokyo Chemical Industry Co., Ltd.; used after recrystallization from ethyl acetate) N,N'-dimethylformamide (DMF) (dried over calcium hydride and purified by distillation) p-iodostyrene

[0190] [Synthesis of Iodine-Containing Monomers] Synthesis Example 1A (Synthesis of 2,4,6-triiodophenyl acrylate (TIPA)) 2,4,6-Triiodophenol (TIP) (30 mmol, 14.4 g) and triethylamine (6 mL) were dissolved in tetrahydrofuran (60 mL) at 0°C to form a solution. Next, acryloyl chloride (AC) (45 mmol, 4.07 mL) was slowly added to the solution. The resulting mixture was then gradually brought to room temperature and stirred for 20 hours. It was then filtered, and the filtrate was concentrated using a rotary evaporator. Chloroform was added to the residue, and the resulting suspension was washed with 0.1 N hydrochloric acid and saturated sodium bicarbonate solution, followed by separation to obtain an organic phase. The organic phase was dried over anhydrous magnesium sulfate and concentrated using a rotary evaporator. The residue was purified by silica gel column chromatography (eluent: chloroform / hexane (1 / 1)) to obtain a white powder. The white powder was dissolved in a chloroform / hexane mixture and recrystallized to obtain 2,4,6-triiodophenyl acrylate (TIPA) as a colorless solid (yield: 12.6 g, 87%). The analytical results are shown below.

[0191] FT-IR (KBr, cm -1 ): 3030 (νC-H aromatic), 1730 (νC=O ester), 1635, 1530 and 702 (νC=C aromatic), 1137 (νC-OC ether), 535 (νI-C halobenzene). 1 H-NMR (400MHz, DMSO-d6, TMS): δ (ppm) = 6.26 (d, J=10.4Hz, 1H, CH2=), 6.45 (dd, 1H, J=6.8Hz, =CH-), 6.62 (d, J=17.6Hz, 1H, CH2=), 8.18 (s, 1H, aromatic H). 13 C-NMR (100MHz, DMSO-d6, TMS): δ (ppm) = 162.08 (C=O), 151.77 (C=C of aromatic), 147.16 (C=C of aromatic), 134.56 (CH2=CH), 127.12 (CH2=CH), 91.71 (C=C of aromatic), 91.66 (C=C of aromatic). Elemental analysis (C9H5I3O2): (calculated value) C20.56, H0.96, I72.40. (Actual measurements) C20.47, H1.05, I72.68.

[0192] [Production of Polymer] Production Example 1A (Production of MP-poly(TIPA) (Chain Transfer Radical Polymerization of 2,4,6-triiodophenylacrylate (TIPA) Using 4-mercaptopyridine (MP) as a Molecular Weight Control Agent)) 2,4,6-Triiodophenylacrylate (TIPA) (1.0 mmol, 0.52 g), 4-mercaptopyridine (MP) (0.1 mmol, 0.11 g), 2,2'-azobis(isobutyronitrile) (AIBN) (3 mol% relative to TIPA, 5.0 mg), and N,N-dimethylformamide (DMF) (0.3 mL) were placed in a polymerization tube and sealed by freeze-degassing. The reaction was then carried out at 60°C for 20 hours. The resulting reaction mixture was diluted with tetrahydrofuran (THF) and poured into methanol, yielding a white solid as a precipitate. The resulting solid was washed with methanol and dried under vacuum at 25°C for 24 hours to obtain MP-poly(TIPA) (yield: 84%). The analytical results are shown below.

[0193] Mn=9,300, Mw / Mn=1.85. FT-IR (KBr, cm -1 ): 2934 (νC-H aliphatic), 1760 (νC=O ester), 1537, 1419 and 832 (νC=C aromatic), 1204 (νC-OC, ether), 534 (νI-C, halobenzene). 1 H-NMR (400MHz, DMSO-d6, TMS): δ (ppm) = 1.64-4.08 (br, CH2 and CH3 in the polymer main chain), 7.57-8.56 (br m, aromatic H).

[0194] Production Examples 2A to 4A (Production of MP-poly(TIPA) (Chain Transfer Radical Polymerization of 2,4,6-Triiodophenylacrylate (TIPA) Using 4-Mercaptopyridine (MP) as a Molecular Weight Control Agent)) MP-poly(TIPA) was obtained in the same manner as in Production Example 1A, except that the amount of 4-mercaptopyridine (MP) was changed to the ratio shown in Table 1A and the amount of 2,2'-azobis(isobutyronitrile) (AIBN) was changed to the same amount as 4-mercaptopyridine (MP). The yield, number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) are shown in Table 1A.

[0195] Production Example 5A (poly(TIPA) ８５ -co-EEA １５ Preparation of (Copolymerization of 2,4,6-triiodophenyl acrylate (TIPA) and 2-(2-ethoxyethoxy)ethyl acrylate (EEA)) 2,4,6-Triiodophenyl acrylate (TIPA) (0.8 mmol, 0.42 g), 2,2'-azobis(isobutyronitrile) (AIBN) (3.0 mol%, 5.0 mg relative to the monomer amount (total amount of TIPA and EEA: 1.0 mmol)), 2-(2-ethoxyethoxy)ethyl acrylate (EEA) (0.2 mmol, 38 mg), and N,N-dimethylformamide (DMF) (0.3 mL) were placed in a polymerization tube and sealed by freeze-degassing. The reaction was then carried out at 60°C for 20 hours. The resulting reaction mixture was diluted with tetrahydrofuran (THF) and poured into methanol to obtain a white solid as a precipitate. The resulting solid was washed with methanol and dried under vacuum at 25°C for 24 hours to obtain poly(TIPA-co-EEA). (Yield: 93%). The analytical results are shown below.

[0196] Mn=19,200, Mw / Mn=2.81. FT-IR (KBr, cm -1 ): 2863 (νC-H aliphatic), 1763 (νC=O ester), 1539, 1420, and 862 (νC=C aromatic), 1207 (νC-OC ether), 536 (νI-C halobenzene). 1H-NMR (400MHz, DMSO-d6, TMS): δ (ppm) = 1.06 (br s, -OCH3), 1.54-3.74 (br, CH2 and CH3 in the polymer main chain), 4.03 (br s, -OCH2-), 8.06 (br s, aromatic H). The polymer composition ratio is １ Based on the integral ratio of the phenyl proton of TIPA at 8.06 ppm and the methyl proton of EEA at 1.06 ppm in H NMR, TIPA / EEA was calculated to be 85 / 15.

[0197] Production Example 6A (poly(TIPA) ７７ -co-HEA ２３ ) (Copolymerization of 2,4,6-triiodophenyl acrylate (TIPA) and 2-hydroxyethyl acrylate (HEA)) Poly(TIPA-co-HEA) was obtained in the same manner as in Production Example 5A, except that the types and amounts of monomers were changed to 2,4,6-triiodophenyl acrylate (TIPA) (0.80 mmol) and 2-hydroxyethyl acrylate (HEA) (0.20 mmol). (Yield: 94%). The analytical results are shown below.

[0198] Mn=14,540, Mw / Mn=1.73. Polymer composition ratio: １ Based on the integral ratio of the phenyl proton of TIPA at 8.07 ppm and the hydroxy proton of HEA at 4.55 ppm in H NMR, TIPA / HEA was calculated to be 77 / 23.

[0199] Production Example 7A (poly(TIPA) ８８ -co-HEA １２ Preparation of Poly(TIPA-co-HEA) (Copolymerization of 2,4,6-triiodophenyl acrylate (TIPA) and 2-hydroxyethyl acrylate (HEA)) Poly(TIPA-co-HEA) was obtained in the same manner as in Preparation Example 5A, except that the amounts of the monomers were changed to 2,4,6-triiodophenyl acrylate (TIPA) (0.90 mmol) and 2-hydroxyethyl acrylate (HEA) (0.10 mmol). The polymer composition ratio, yield, number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) are shown in Table 1A.

[0200] Production Example 8A (poly(TIPA) ７０ -co-EEA ２０ -co-GMA １０ ) (Copolymerization of 2,4,6-triiodophenyl acrylate (TIPA), 2-(2-ethoxyethoxy)ethyl acrylate (EEA), and glycidyl methacrylate (GMA)) Poly(TIPA-co-HEA) was obtained in the same manner as in Production Example 5A, except that the types and amounts of monomers used were 2,4,6-triiodophenyl acrylate (TIPA) (0.7 mmol), 2-(2-ethoxyethoxy)ethyl acrylate (EEA) (0.2 mmol), and glycidyl methacrylate (GMA) (0.1 mmol). The yield was 89%. The analytical results are shown below.

[0201] Mn=24,500, Mw / Mn=3.58. FT-IR (KBr, cm -1 ): 2923 (νC-H aliphatic), 1764 (νC=O ester), 1538, 1420, and 861 (νC=C aromatic), 1108 (νC-OC ether), 903 (νepoxy), and 531 (νI-Chalobenzene). 1 H-NMR (400MHz, DMSO-d6, TMS): δ (ppm) = 1.06 (br s, -OCH3), 1.24-3.77 (br, CH2 and CH3 in the polymer main chain), 4.01 (br s, -OCH2-), 8.05 (br s, aromatic H). The polymer composition ratio is １ Based on the integral ratio of the phenyl proton of the TIPA portion at 8.05 ppm, the methyl proton of the EEA portion at 1.06 ppm, and the methylene proton of the GMA portion at 4.01 ppm in H NMR, the ratio was calculated to be TIPA / EEA / GMA=70 / 20 / 10.

[0202] Preparation Example 9A (Preparation of TBBT-poly(p-iodostyrene) (p-iodostyrene / TBBT = 6 / 1 (molar ratio)) (Chain transfer radical polymerization of p-iodostyrene using 4,4'-thiobisbenzenethiol (TBBT) as a molecular weight control agent) p-Iodostyrene (0.345 g, 1.5 mmol), 4,4'-thiobisbenzenethiol (TBBT) (0.065 g, 0.25 mmol), 2,2'-azobis(isobutyronitrile) (AIBN) (0.082 g, 0.5 mmol), and N,N-dimethylformamide (DMF) (2.0 mL) were placed in a polymerization tube and sealed by freeze-degassing. The mixture was then allowed to react at 60°C for 20 hours. The resulting reaction mixture was poured into water, yielding a white solid as a precipitate. The obtained solid was dried at 60°C for 12 hours to obtain TBBT-poly(p-iodostyrene) (yield: approximately 90%). １ The number average molecular weight was about 1,800 as determined by H-NMR and IR spectroscopy.

[0203] Production Example 10A (Production of TBBT-poly(p-iodostyrene) (p-iodostyrene / TBBT = 12 / 1 (molar ratio)) (Chain transfer radical polymerization of p-iodostyrene using 4,4'-thiobisbenzenethiol (TBBT) as a molecular weight control agent) TBBT-poly(p-iodostyrene) was obtained in the same manner as in Production Example 9A, except that the amount of p-iodostyrene was changed to 0.69 g (3.0 mmol) (yield: approximately 85%). The number average molecular weight was approximately 4,000.

[0204] [Preparation of Lithography Underlayer Film-Forming Compositions] Examples 1A to 29A and Comparative Examples 1A to 2A Lithography underlayer film-forming compositions were prepared according to the formulations shown in Table 2A. In Table 2A, the numbers in parentheses indicate the content (blending amount) (parts by mass) of each component. The solvent ratios are also mass ratios. The polymers used in the examples were the polymers obtained in Preparation Examples 1A to 10A, and a phenol novolak resin (manufactured by Gun-ei Chemical Co., Ltd., product name: PSM4357) was used in the comparative example. The acid generators, crosslinkers, and organic solvents used were as follows. The resulting lithography underlayer film-forming compositions were used for film-formability evaluation, EB pattern evaluation, and EUV exposure evaluation. The results are shown in Tables 2A to 4A.

[0205] Acid generator: "Di-tertiary butyldiphenyliodonium nonafluorobutanesulfonate" manufactured by Midori Chemical Co., Ltd. (referred to as "DTDPI" in the table) Pyridinium paratoluenesulfonate (referred to as "PPTS" in the table) Crosslinker: "Nicalac MX270" manufactured by Sanwa Chemical Co., Ltd. (referred to as "Nicalac" in the table) "TMOM-BP" manufactured by Honshu Chemical Industry Co., Ltd. (referred to as "TMOM" in the table) Organic solvent: PGMEA / PGME = 7:3 PGMEA: propylene glycol monomethyl ether acetate PGME: 1-methoxy-2-propanol (propylene glycol monomethyl ether)

[0206]

[0207]

[0208]

[0209]

[0210] From the above results, it can be seen that the lithography underlayer film-forming compositions of the examples are excellent in EB sensitivity and EUV sensitivity, and have high exposure sensitivity. Furthermore, it can be seen that the lithography underlayer film-forming compositions of the examples are also excellent in film-forming properties. It can also be seen that the polymers contained in the lithography underlayer film-forming compositions of the examples have high solubility in solvents. From the above, it can be seen that the lithography underlayer film-forming composition of the present invention can increase the exposure sensitivity in the lithography process and is an excellent material for forming a lithography underlayer film. Furthermore, the polymers contained in the lithography underlayer film-forming composition of the present invention are also highly soluble and have excellent film-forming properties, making them an excellent material for forming a lithography underlayer film.

[0211] [2] Examples of Positive Resist Compositions (Second Invention) [Analysis] Fourier transform infrared spectroscopy (FT-IR) spectra were measured using a JASCO FT / IR4200 (manufactured by JASCO Corporation). 1 H-NMR spectrum, 13 C-NMR spectra were measured using an FTECS-400K (manufactured by JEOL Ltd.) at a frequency of 400 MHz, using DMSO-d as the solvent and MeSi(TMS) as the internal standard. The number-average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the polymer were measured by size exclusion chromatography (SEC) under the following conditions. Standard polystyrene (narrow molecular weight distribution) was used for calibration. (Measurement conditions: Apparatus: HLC-8220 SEC apparatus, manufactured by Tosoh Corporation; Columns: TSKgel Super AW3000, AW2500 x 2; Detection: RI, UV; Eluent: DMF (20 mM) solution of LiBr and phosphoric acid; Flow rate: 0.6 mL / min)

[0212] [Evaluation 1] <Solubility> The solubility of the polymer was confirmed in the following solvents at room temperature (25°C). The solvents tested were DMF (N,N-dimethylformamide), NMP (N-methylpyrrolidone), MEK (methyl ethyl ketone), PGME, and PGMEA. For these solvents, the solubility was evaluated as "good (A)" when 3 mg or more of the resin dissolved in 1 mL of the solvent.

[0213] <Film-forming property and film-removal property> A methyl ethyl ketone (MEK) solution (2% by mass) of the polymer was applied by spin coating (2800 rpm, 30 seconds) onto a silicon wafer treated with hexamethyldisilazane (HMDS) to form a thin film. The film thickness was measured using a film thickness measuring device (Ellipsometer SE-101 (manufactured by Photonic Lattice Co., Ltd.), surface profiling system Dektak-XT (manufactured by Bruker)) (measurement wavelength 636 nm). The film-forming property is recorded as the thickness of a thin film that could be formed, and these are evaluated as having good film-forming property. The film thickness was measured using a film thickness measuring device (Ellipsometer SE-101 (manufactured by Photonic Lattice Co., Ltd.), surface profiling system Dektak-XT (manufactured by Bruker)) (measurement wavelength 636 nm). Regarding film-forming properties, those that could form the above-mentioned thin film (film) had good film-forming properties. Next, the film thickness after immersion in a 2.38% by mass TMAH (tetramethyl ammonium hydroxide) aqueous solution was measured. The difference between the film thickness before immersion in the TMAH aqueous solution and the film thickness after immersion in the TMAH aqueous solution was determined, and the value (%) obtained by dividing by the film thickness before immersion in the TMAH aqueous solution was evaluated as film loss property. The smaller the film thickness after immersion in the TMAH aqueous solution compared to the film thickness before immersion in the TMAH aqueous solution, the more suppressed film loss is, and this is preferable, and those that do not decrease are more suppressed film loss, and are therefore more preferable. This is to evaluate the usefulness as a positive resist material, particularly when using an alkaline developer.

[0214] [Synthesis of Iodine-Containing Monomers] Synthesis Example 1B (Synthesis of 2,4,6-triiodophenyl acrylate (TIPA)) 2,4,6-Triiodophenol (TIP) (15 mmol, 7.08 g) and triethylamine (20 mL) were dissolved in tetrahydrofuran (20 mL) at 0°C to form a solution. Next, acryloyl chloride (AC) (20 mmol, 1.81 g, 1.62 mL) was slowly added to the solution. The resulting mixture was then gradually brought to room temperature (25°C) and stirred for 24 hours. It was then filtered, and the filtrate was concentrated using a rotary evaporator. Chloroform was added to the residue, and the resulting suspension was washed with 0.1 N hydrochloric acid and saturated sodium bicarbonate solution, followed by separation to obtain an organic phase. The organic phase was dried over anhydrous magnesium sulfate and concentrated using a rotary evaporator. The residue was purified by silica gel column chromatography (eluent: chloroform / hexane (1 / 1)) to obtain a white powder. The white powder was dissolved in a chloroform / hexane mixture and recrystallized to obtain 2,4,6-triiodophenyl acrylate (TIPA) as a colorless solid (yield: 46.0%). The analytical results are shown below.

[0215] FT-IR (KBr, cm -1 ): 3030 (νC-H aromatic), 1730 (νC=O ester), 1635, 1530 and 702 (νC=C aromatic), 1137 (νC-OC ether), 535 (νI-C halobenzene). 1 H-NMR (400MHz, DMSO-d6, TMS): δ (ppm) = 6.26 (d, J=10.4Hz, 1H, CH2=), 6.45 (dd, 1H, J=6.8Hz, =CH-), 6.62 (d, J=17.6Hz, 1H, CH2=), 8.18 (s, 1H, aromatic H). 13 C-NMR (100MHz, DMSO-d6, TMS): δ (ppm) = 162.08 (C=O), 151.77 (C=C of aromatic), 147.16 (C=C of aromatic), 134.56 (CH2=CH), 127.12 (CH2=CH), 91.71 (C=C of aromatic), 91.66 (C=C of aromatic). Elemental analysis (C9H5I3O2): (calculated value) C20.56, H0.96, I72.40. (Actual measurements) C20.47, H1.05, I72.68.

[0216] [Production of Polymer] Production Example 1B (Production of Poly(HS-co-TIPA-co-ADA)) 2,4,6-Triiodophenyl acrylate (TIPA), 4-vinylphenyl acetate (VPA), and 2-methyladamantan-2-yl acrylate (ADA) were charged in a charge ratio of VPA:TIPA:ADA = 9:4:7, and polymerized using azobisisobutyronitrile (AIBN) as an initiator in N,N-dimethylformamide (DMF) at 60°C for 20 hours to obtain the corresponding copolymer (Poly(VPA-co-TIPA-co-ADA)) in 88% yield. Next, the copolymer was hydrolyzed with an aqueous sodium hydroxide solution to obtain the corresponding polymer (Poly(HS-co-TIPA-co-ADA)). The analytical results are shown below. Table 1B also shows the results of solubility evaluation, film-forming ability evaluation, and film-loss evaluation.

[0217] Yield 97%. Mn=25,770, Mw / Mn=3.51.

[0218]

[0219] The results in Table 1B show that the polymer obtained in Production Example 1B has high solubility in solvents and excellent film-forming properties. It is also found that the polymer has good film-removal properties in a developer. Therefore, it is clear that the polymer containing a repeating unit derived from the iodine-containing monomer represented by formula (1B) of the present invention is an excellent material for forming a lithography film, and particularly an excellent material for forming a resist film.

[0220] [Preparation and Evaluation of Positive Resist Composition] Comparative Synthesis Example 1B (Synthesis of Modified Dimethylnaphthalene Formaldehyde Resin CR-1) A four-necked flask with a bottomless opening and a volume of 10 L was prepared, equipped with a Dimroth condenser, a thermometer, and a stirring blade. Into this four-necked flask, 1.09 kg (7 mol, manufactured by Mitsubishi Gas Chemical Co., Inc.), 2.1 kg of a 40% by weight aqueous formalin solution (28 mol as formaldehyde, manufactured by Mitsubishi Gas Chemical Co., Inc.), and 0.97 mL of 98% by weight sulfuric acid (manufactured by Kanto Chemical Co., Inc.) were charged in a nitrogen stream, and the mixture was refluxed at 100°C under normal pressure (atmospheric pressure) for 7 hours. Subsequently, 1.8 kg of ethylbenzene (special grade reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a diluent to the reaction solution. After allowing to stand, the lower aqueous phase was removed. The mixture was neutralized and washed with water, and the ethylbenzene and unreacted 1,5-dimethylnaphthalene were distilled off under reduced pressure to obtain 1.25 kg of a light brown solid dimethylnaphthalene formaldehyde resin. The molecular weight Mn of the resulting dimethylnaphthalene formaldehyde resin was 562.

[0221] Next, a four-neck flask with an internal volume of 0.5 L equipped with a Dimroth condenser, a thermometer, and a stirring blade was prepared. Into this four-neck flask, 100 g (0.51 mol) of the dimethylnaphthalene formaldehyde resin and 0.05 g of paratoluenesulfonic acid were charged under a nitrogen stream, and the temperature was raised to 190 ° C. and heated for 2 hours, followed by stirring. Then, 52.0 g (0.36 mol) of 1-naphthol was added, and the temperature was further raised to 220 ° C. and reacted for 2 hours. After dilution with a solvent, neutralization and washing with water were performed, and the solvent was removed under reduced pressure to obtain 126.1 g of a modified resin (CR-1) as a black-brown solid. The resulting resin (CR-1) had an Mn of 885, an Mw of 2220, and an Mw / Mn of 4.17. The Mn, Mw and Mw / Mn of the resin (CR-1) were determined in terms of polystyrene by gel permeation chromatography (GPC) analysis under the following measurement conditions: Apparatus: Shodex GPC-101 (product of Showa Denko K.K.) Column: KF-80M x 3 Eluent: THF 1 mL / min Temperature: 40°C

[0222] Examples A1B to A2B and Comparative Example A1B (Production of positive resist composition and resist film) Positive resist compositions with the compositions shown in Table 2B were prepared using the polymer obtained in Production Example 1B and the resin obtained in Comparative Synthesis Example 1B. In addition, a positive resist composition using a novolak resin (PSM4357 (model number) manufactured by Gunei Chemical Industry Co., Ltd.) was also prepared as a reference for evaluating etching resistance.

[0223] The acid generator, acid diffusion controller, and organic solvent used were as follows. In Table 2B, the values ​​in parentheses indicate the blending amounts (parts by mass). <Acid Generator> TPS-109: Triphenylsulfonium trifluoromethanesulfonate, TPS-109 (trade name), manufactured by Midori Chemical Co., Ltd. DTDPI: Di-tertiarybutyldiphenyliodonium nonafluorobutanesulfonate (DTDPI), manufactured by Midori Chemical Co., Ltd. <Acid Diffusion Controller> TOA: Tri-n-octylamine (TOA, manufactured by Kanto Chemical Co., Ltd.) <Organic Solvent> PGME: Propylene glycol monomethyl ether (PGME, manufactured by Kanto Chemical Co., Ltd.) PGMEA: Propylene glycol monomethyl ether acetate (PGMEA, manufactured by Kanto Chemical Co., Ltd.)

[0224]

[0225] [Evaluation 2] (1) Formation of Resist Film The positive resist compositions (Examples A1B to A2B and Comparative Example A1B) shown in Table 2B were spin-coated onto a silicon wafer that had been treated with hexamethyldisilazane (HMDS). After that, a pre-exposure bake (PB) was carried out in an oven at 110°C to form a resist film with a thickness of 40 nm.

[0226] (2) Formation of Resist Pattern The resist film obtained in (1) above was irradiated with an electron beam using an electron beam lithography system (ELS-7500, manufactured by Elionix Co., Ltd., 50 keV) in a 1:1 line-and-space setting with 50 nm spacing. After irradiation, the resist film was heated at 110°C for 90 seconds and immersed in a developer for 60 seconds for development. The resist film was then washed with ultrapure water for 30 seconds and dried to form a resist pattern. In Examples A1B to A2B, a 2.38% by mass aqueous solution of TMAH was used as the developer, and in Comparative Example A1B, propylene glycol monomethyl ether (PGME) was used as the developer.

[0227] The shape of the resulting L / S (1:1) resist pattern with 50 nm spacing was observed using an electron microscope (S-4800, product name) manufactured by Hitachi, Ltd. The resist pattern shape after development was evaluated according to the following criteria. The results are shown in Table 3B. A: No pattern collapse, and rectangularity was better than that of Comparative Example A1B. B: The rectangularity was better than that of Comparative Example A1B, but pattern collapse was observed in 1 to 3 places within an area of ​​1 μm × 1.5 μm. C: Equivalent to or inferior to Comparative Example A1B. In Comparative Example A1B, pattern collapse was observed in the resist pattern shape after development, and rectangularity was poor.

[0228] (3) Etching Resistance The positive resist compositions shown in Table 2B (Examples A1B to A2B and Comparative Example A1B) were spin-coated onto silicon wafers that had been treated with hexamethyldisilazane (HMDS). They were then pre-exposure baked (PB) in an oven at 110°C to form resist films with a thickness of 40 nm. An etching test was conducted on the resist films, and the etching rates were measured. The etching conditions were as follows:

[0229] (Etching conditions) Etching equipment: RIE-10NR (product name) manufactured by Samco Corporation, Output: 50 W, Pressure: 20 Pa, Time: 2 minutes, Etching gas: Ar gas, Flow rate: CF ４ Gas flow rate: 0 ２ Gas flow rate = 50:5:5 (sccm)

[0230] The etching resistance of each resist film was evaluated according to the following evaluation criteria, using the etching rate of a resist film obtained from an evaluation composition using a novolac resin as the standard. The results are shown in Table 3B. (Evaluation Criteria) A: The etching rate was less than -10% compared to a novolac resin resist film. B: The etching rate was -10% or more but less than 0% compared to a novolac resin resist film. C: The etching rate was 0% or more compared to a novolac resin resist film.

[0231]

[0232] The results of the examples show that resist patterns formed using a positive resist composition containing a polymer containing a repeating unit derived from an iodine-containing monomer represented by formula (1B) of the present invention are free from pattern collapse and exhibit excellent resolution. Furthermore, it is also clear that resist films formed using a positive resist composition containing a polymer containing a repeating unit derived from an iodine-containing monomer represented by formula (1B) of the present invention exhibit excellent etching resistance. From the above, it is clear that the positive resist composition of the present invention is an excellent material for forming a resist film. It is also clear that resist patterns formed using the positive resist composition exhibit excellent resolution.

Claims

1. A lithography underlayer film-forming composition containing a polymer containing a repeating unit derived from an iodine-containing monomer represented by the following general formula (1A). (In the formula, X 1A is a hydrogen atom, a methyl group or a halogen atom, Y 1A is -O- or -NH-, aa is 0 or 1, and R A is an organic group containing an iodine atom having 2 to 30 carbon atoms.) 2. R A The lithography underlayer film-forming composition according to claim 1, wherein R is an organic group represented by the following general formula (2A). (In the formula, L A is a direct bond or a divalent organic group having 1 to 24 carbon atoms. ba is an integer of 1 to 5.) 3. R A The lithography underlayer film forming composition according to claim 1 or 2, wherein R is at least one selected from the group consisting of an organic group represented by the following general formula (3A) and an organic group represented by the following general formula (4A). (In the formula, L A is a direct bond or a divalent organic group having 1 to 24 carbon atoms.) 4. The lithography lower layer film forming composition according to any one of claims 1 to 3, further containing a solvent.

5. The lithography lower layer film forming composition according to any one of claims 1 to 4, containing at least one selected from the group consisting of an acid generator and an acid crosslinking agent.

6. The lithography lower layer film formed from the lithography lower layer film forming composition according to claim 5.

7. A resist pattern forming method using the lithography lower layer film forming composition according to claim 5.

8. A positive resist composition containing a polymer containing a repeating unit derived from an iodine-containing monomer represented by the following formula (1B). (In the formula, X 1B is a hydrogen atom, a methyl group, or a halogen atom, Y 1B is -O- or -NH-, ab is 0 or 1, and R B is a group having 2 to 30 carbon atoms containing an iodine atom.) 9. R B The positive resist composition according to claim 8, wherein R is a group represented by the following formula (2B). (In the formula, L B is a direct bond or a divalent group having 1 to 24 carbon atoms, and each R １B is independently an alkyl group having 1 to 30 carbon atoms which may have a substituent, an aryl group having 6 to 30 carbon atoms which may have a substituent, an alkenyl group having 2 to 30 carbon atoms which may have a substituent, an alkynyl group having 2 to 30 carbon atoms which may have a substituent, an alkoxy group having 1 to 30 carbon atoms which may have a substituent, a halogen atom other than iodine, a nitro group, an amino group, a carboxylic acid group, a crosslinkable group, a dissociable group, a thiol group, or a hydroxyl group. bb is an integer of 1 to 5, cb is an integer of 0 to 4, and bb + cb is 1 to 5.) 10. R B The positive resist composition according to claim 8 or 9, wherein R is at least one selected from the group consisting of a group represented by the following formula (3B) and a group represented by the following formula (4B). (In the formula, L B is a direct bond or a divalent group having 1 to 24 carbon atoms.) 11. The positive resist composition according to any one of claims 8 to 10, wherein the polymer further contains a repeating unit derived from a phenolic hydroxyl group-containing monomer.

12. The positive resist composition according to claim 11, wherein the phenolic hydroxyl group-containing monomer is at least one selected from the group consisting of 4-vinylphenol, 4-hydroxyphenyl (meth)acrylate, and 4-hydroxyphenyl (meth)acrylamide.

13. The positive resist composition according to claim 11 or 12, wherein the phenolic hydroxyl group-containing monomer is 4-vinylphenol.

14. The positive resist composition according to any one of claims 11 to 13, wherein the molar ratio [phenolic hydroxyl group-containing monomer / iodine-containing monomer] of the repeating unit derived from the phenolic hydroxyl group-containing monomer to the repeating unit derived from the iodine-containing monomer represented by the formula (1B) is 20 / 80 to 95 / 5.

15. The positive resist composition according to any one of claims 8 to 14, wherein the polymer further contains a repeating unit derived from an adamantane structure-containing monomer.

16. The positive resist composition according to claim 15, wherein the adamantane structure-containing monomer is at least one selected from the group consisting of adamantan-1-yl (meth)acrylate, 2-methyladamantan-2-yl (meth)acrylate, 2-ethyladamantan-2-yl (meth)acrylate, and N-(1-adamantyl)(meth)acrylamide.

17. The positive resist composition according to claim 15 or 16, wherein the adamantane structure-containing monomer is 2-methyladamantan-2-yl (meth)acrylate.

18. The positive resist composition according to any one of claims 15 to 17, wherein the molar ratio [adamantane structure-containing monomer / iodine-containing monomer] of the repeating unit derived from the adamantane structure-containing monomer to the repeating unit derived from the iodine-containing monomer represented by the formula (1B) is 20 / 80 to 99 / 1.

19. The positive resist composition according to any one of claims 8 to 18, further comprising a solvent.

20. The positive resist composition according to any one of claims 8 to 19, further comprising at least one selected from the group consisting of an acid generator and a crosslinking agent.

21. A resist film formed from the positive resist composition according to any one of claims 8 to 20.

22. A method for forming a resist pattern, using the positive resist composition according to any one of claims 8 to 20.

23. A method for forming a resist pattern, comprising: forming a resist film on a substrate using the positive resist composition according to any one of claims 8 to 20; and exposing and developing the resist film.

Images