Lithography film-forming composition, resist film, and pattern forming method

Abstract

The present invention provides a lithography film-forming composition, a resist film, and a pattern forming method, with which it is possible to form a film having high resolution and high sensitivity. A lithography film-forming composition according to the present invention comprises a polymer (A), a photoacid generator (B), and an acid diffusion inhibitor (C). The polymer (A) includes a repeating unit having an acid-dissociable group. At least one selected from the group consisting of the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C) has an adamantane backbone.

Description

Lithography film formation composition, resist film, and pattern formation method

[0001] The present invention relates to a lithography film formation composition, a resist film, and a pattern formation method.

[0002] In recent years, advances in lithography technology have led to rapid miniaturization of semiconductors (patterns) and pixels in the manufacturing of semiconductor devices and liquid crystal display elements. Generally, the miniaturization of pixels is achieved by shortening the wavelength of the exposure light source. Specifically, while ultraviolet light, such as the g-line and i-line, was traditionally used, far-ultraviolet exposure using KrF excimer lasers (248 nm) and ArF excimer lasers (193 nm) is now becoming the focus of mass production, and the introduction of extreme ultraviolet (EUV) lithography (13.5 nm) is also progressing. Furthermore, electron beams (EB) are also used to form fine patterns.

[0003] Conventional resist materials are polymer-based resist materials capable of forming amorphous films. Examples include polymer-based resist materials such as polymethyl methacrylate and polyhydroxystyrene or polyalkyl methacrylate having acid-dissociable groups (see, for example, Non-Patent Document 1). Conventionally, line patterns of about 10 to 100 nm are formed by irradiating a resist thin film, prepared by coating a solution of these resist materials onto a substrate, with ultraviolet light, far ultraviolet light, electron beams, extreme ultraviolet light, etc.

[0004] Furthermore, electron beam or extreme ultraviolet lithography has a reaction mechanism different from that of conventional photolithography. Moreover, electron beam or extreme ultraviolet lithography aims to form fine patterns of several nanometers to tens of nanometers. As the resist pattern size becomes smaller in this way, a resist material that is even more sensitive to the exposure light source is required. In particular, extreme ultraviolet lithography requires even higher sensitivity in terms of throughput. To improve the above-mentioned problems, inorganic resist materials containing metallic elements such as titanium, tin, hafnium, and zirconium have been proposed (see, for example, Patent Document 1).

[0005] Japanese Patent Publication No. 2015-108781

[0006] Shinji Okazaki, et al., "40 Years of Lithography Technology," S&T Publishing, December 9, 2016.

[0007] However, conventionally developed resist compositions have challenges in achieving both high resolution and high sensitivity.

[0008] In view of the above circumstances, the present invention aims to provide a lithography film-forming composition, a resist film, and a pattern-forming method that can form films having high resolution and high sensitivity.

[0009] As a result of diligent research to solve the above problems, the present inventors have found that by applying a lithography film-forming composition comprising a specific polymer (A), a photoacid generator (B), and an acid diffusion inhibitor (C), wherein at least one selected from the group consisting of polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) has an adamantane skeleton, to lithography film-forming applications and resist film-forming applications, films with high resolution and high sensitivity can be formed, and have completed the present invention. That is, the present invention is as follows.

[0010] [1] A lithography film-forming composition comprising a polymer (A), a photoacid generator (B), and an acid diffusion inhibitor (C), wherein the polymer (A) comprises repeating units having an acid-dissociable group, and at least one selected from the group consisting of the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C) has an adamantane skeleton.

[0011] [2] The lithography film-forming composition according to [1], wherein the polymer (A) contains an adamantane skeleton, and the content of the adamantane skeleton in the polymer (A) is 33% by mass or more with respect to 100% by mass of the polymer (A), when the mass of one adamantane skeleton is 136.

[0012] [3] The lithography film-forming composition according to [1] or [2], wherein the polymer (A) has repeating units represented by formula (1).

[0013]

[0014] (In formula (1), R １ R represents a hydrogen atom, a methyl group, or a halogen atom. ２ Each independently represents a hydrogen atom, a linear organic group having 1 to 20 carbon atoms, a branched organic group having 3 to 20 carbon atoms, or a cyclic organic group having 3 to 20 carbon atoms; A represents an adamantane group which may have substituents; L represents an ester bond (-COO-), a single bond, or an oxygen atom; n １ n represents 0 or 1. ２ (where represents an integer between 0 and 20, and the symbol * indicates a connection point with an adjacent repeating unit.)

[0015] [4] The lithography film-forming composition according to [3], wherein the repeating unit represented by formula (1) is the repeating unit represented by formula (8).

[0016]

[0017] (In formula (8), R １ , R ２ , L, n １ , and the symbol * are as defined in formula (1) above, RＡ each independently represents a hydrogen atom, a linear organic group having 1 to 20 carbon atoms, a branched organic group having 3 to 20 carbon atoms, or a cyclic organic group having 3 to 20 carbon atoms, and n １ A represents 1 or 2, and n １ B represents 1 or 2, and n １ C represents 0 or 1).

[0018] [5] When the mass per adamantane skeleton is 136, the content of all adamantane skeletons contained in the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C) is 28% by mass or more with respect to the total 100% by mass of the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C). The composition for forming a lithography film according to any one of [1] to [4].

[0019] [6] The polymer (A) contains an iodine atom, the content of the iodine atom contained in the polymer (A) is 41% by mass or less with respect to 100% by mass of the polymer (A), and at least one selected from the group consisting of the photoacid generator (B) and the acid diffusion inhibitor (C) contains an iodine atom. The content of all iodine atoms contained in the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C) is 2% by mass or more with respect to the total 100% by mass of the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C). The composition for forming a lithography film according to any one of [1] to [5].

[0020] [7] The polymer (A) contains an iodine atom, and the content of the iodine atom contained in the polymer (A) exceeds 41% by mass with respect to 100% by mass of the polymer (A). The composition for forming a lithography film according to any one of [1] to [6].

[0021] [8] The photoacid generator (B) has an adamantane skeleton. The composition for forming a lithography film according to any one of [1] to [7].

[0022] [9] The acid diffusion inhibitor (C) has an adamantane skeleton. The composition for forming a lithography film according to any one of [1] to [8].

[0023] A resist film formed from any one of the lithography film-forming compositions described in

[10] , [1], to [9].

[0024] A pattern forming method comprising the steps of: forming a resist film using a lithography film forming composition described in any one of [1] to [9]; exposing the resist film using extreme ultraviolet light (EUV); and removing the exposed portion of the resist film using a developer to form a pattern.

[0025] According to the present invention, it is possible to provide a lithography film-forming composition, a resist film, and a pattern-forming method that can form films having high resolution and high sensitivity.

[0026] The embodiments of the present invention will be described below (hereinafter sometimes referred to as "this embodiment"). This embodiment is an example for illustrating the present invention, and the present invention is not limited to this embodiment.

[0027] In this specification, (meth)acrylate means acrylate and methacrylate. Other terms containing the expression (meth) shall be interpreted in the same way as (meth)acrylate.

[0028] In this specification, the term "polymer" includes both homopolymers and copolymers.

[0029] In this specification, the component that provides repeating units in a polymer is also referred to as a compound or monomer. The constituent units in a polymer that originate from a compound or monomer are also referred to as monomer units.

[0030] In this specification, examples of substituents include halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, amino groups, thiol groups, heterocyclic groups, linear aliphatic hydrocarbon groups, branched aliphatic hydrocarbon groups, cyclic aliphatic hydrocarbon groups, aryl groups, aralkyl groups, alkoxy groups, aryloxy groups, alkenyl groups, acyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, alkylyloxy groups, arylloyloxy groups, alkylsilyl groups, alkylsiloxy groups which may have an aryl group, and various crosslinkable groups and acid-dissociable groups. Furthermore, these groups may contain ether bonds, ketone bonds, and ester bonds.

[0031] In this specification, a crosslinkable group is a group that crosslinks with acid, alkali, light, or heat, and that crosslinks in the presence or absence of a catalyst. Examples of crosslinkable groups include groups having an allyl group, a (meth)acryloyl group, an epoxy (meth)acryloyl group, a urethane (meth)acryloyl group, a hydroxyl group, a glycidyl group, a vinylphenylmethyl group, a styrene group, an alkynyl group, a carbon-carbon double bond, a carbon-carbon triple bond, and groups containing these groups.

[0032] In this specification, acid-dissociable groups include, for example, carboxylic acid ester groups, groups in which a hydroxyl group is protected with a substituted methyl group, groups in which a hydroxyl group is protected with a 1-substituted ethyl group, groups in which a hydroxyl group is protected with a 1-substituted n-propyl group, groups in which a hydroxyl group is protected with a silyl group, and groups that cleave in the presence of an acid to produce an alkali-soluble group. An example of a group in which a hydroxyl group is protected with a substituted methyl group is -OCH ２ OCH ３ , -OCH ２ OCH ２ CH ３ , -OCH ２ OCH ２ OCH ３ , -OCH ２ OCH ２ OCH ２ CH ３ , -OCH ２ OCH２ CH ２ OCH ３ , and -OCH ２ OCH ２ CH ２ OCH ２ CH ３ Examples include -OCH(CH ３ ) OCH ３ , -OCH(CH ３ ) OCH ２ CH ３ , -OCH(CH ３ ) OCH ２ OCH ３ , -OCH(CH ３ ) OCH ２ OCH ２ CH ３ , -OCH(CH ３ ) OCH ２ CH ２ OCH ３ , and -OCH(CH ３ ) OCH ２ CH ２ OCH ２ CH ３ Examples include: a group in which a hydroxyl group is protected with a 1-substituted n-propyl group, for example, -OCH(CH ２ CH ３ ) OCH ３ , -OCH(CH ２ CH ３ ) OCH ２ CH ３ , -OCH(CH ２ CH ３ ) OCH ２ OCH ３ , -OCH(CH ２ CH ３ ) OCH ２ OCH ２ CH ３ , -OCH(CH ２ CH ３ ) OCH ２ CH ２ OCH ３ , and -OCH(CH ２ CH ３ ) OCH ２ CH ２ OCH２ CH ３ Examples include -OSi(CH ３ ) ３ , and -OSi(Ph)(CH ３ ) ２ Examples of alkali-soluble groups include phenolic hydroxyl groups, carboxyl groups, sulfonic acid groups, and hexafluoroisopropanol groups. Acid-dissociable groups can be appropriately selected from those proposed for use in hydroxystyrene resins and (meth)acrylic resins used in chemically amplified resist compositions for KrF and ArF. Examples of acid-dissociable groups include those described in International Publication No. 2016 / 158168. More specifically, acid-dissociable groups include acetal-type acid-dissociable groups, tertiary alkyl ester-type acid-dissociable groups such as t-butyl ester groups, tertiary alkyloxycarbonyl acid-dissociable groups, and secondary alkyloxycarbonyl acid-dissociable groups.

[0033] In this specification, an organic group refers to a functional group composed of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, silicon atoms, sulfur atoms, and halogen atoms. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0034] In this specification, the adamantane skeleton refers to a hydrocarbon with a cage-like structure in which 10 carbon atoms are bonded together in an arrangement similar to that of diamond, as represented by formula (2). The adamantane skeleton may have substituents and organic groups. Examples of substituents and organic groups include those described above. Furthermore, when the adamantane skeleton is bonded to the structure of a compound, polymer, or resin (for example, a resin used as a resist material), the adamantane skeleton may also be referred to as the adamantane group.

[0035]

[0036] [Lithography Film Forming Composition] The lithography film forming composition of this embodiment (hereinafter also simply referred to as "forming composition") comprises a polymer (A) (hereinafter also simply referred to as "polymer"), a photoacid generator (B) (hereinafter also simply referred to as "photoacid generator"), and an acid diffusion inhibitor (C) (hereinafter also simply referred to as "acid diffusion inhibitor"), wherein polymer (A) comprises repeating units having acid-dissociable groups, and at least one selected from the group consisting of polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) has an adamantane skeleton. Because the adamantane skeleton has excellent propagation properties for protons generated by EUV, for example, the EUV sensitivity of the forming composition tends to be further improved by including a component having an adamantane skeleton. Such effects can be obtained not only when polymers or resins have an adamantane skeleton, but also when low molecular weight compounds, such as oligomer components or additives, have an adamantane skeleton. Therefore, when the forming composition is applied to lithography film formation or resist film formation applications, it tends to be possible to form films with high resolution and high sensitivity.

[0037] The inclusion of a component having an adamantane skeleton in the forming composition tends to improve the EB sensitivity of the forming composition. The reason for this is not entirely clear, but it is thought that a portion of the EB irradiation energy generates protons, which propagate through the adamantane skeleton, which has excellent propagation properties. However, the reason is not limited to this.

[0038] The adamantane skeleton may be directly bonded in at least one selected from the group consisting of polymers, photoacid generators, and acid diffusion inhibitors, or it may be indirectly bonded, such as being contained in a counterion in the acid produced from the photoacid generator.

[0039] In at least one selected from the group consisting of a polymer, a photoacid generator, and an acid diffusion inhibitor, there is at least one adamantane skeleton, preferably one to five, and more preferably one to four. Here, the number of adamantane skeletons in the polymer is the number of adamantane skeletons in the monomer unit (U) containing the adamantane skeleton, and if there are multiple types of monomer units (U) containing the adamantane skeleton, the number of adamantane skeletons in them is the total number.

[0040] In the forming composition, when the mass per adamantane skeleton is 136, the total content of adamantane skeletons in the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) is preferably 3% by mass or more, more preferably 26% by mass or more, even more preferably 28% by mass or more, even more preferably 31% by mass or more and 50% by mass or less, and even more preferably 33% by mass or more and 40% by mass or less, based on 100% by mass of the total of the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C). When the adamantane skeleton content is within the above range, the forming composition tends to be able to form films with higher resolution and higher sensitivity.

[0041] In the composition for forming, the total adamantane skeleton content in the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) is calculated as the amount relative to 100% by mass of the total of the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C), based on the following formula (i), with the mass of one adamantane skeleton being 136.

[0042]

[0043] In the film-forming composition, it is preferable that at least one selected from the group consisting of polymers, photoacid generators, and acid diffusion inhibitors contains an iodine atom. Iodine atoms have a relatively high EUV absorption rate and readily absorb EUV to generate a large amount of electrons and protons. Therefore, by including a component having an iodine atom in the film-forming composition, the EUV sensitivity of the film-forming composition tends to be further improved. Such an effect can be obtained not only when the polymer or resin contains an iodine atom, but also when, for example, a low molecular weight compound such as an oligomer component or additive contains an iodine atom. As described above, the film-forming composition contains a component having an adamantane skeleton. By including a component having an adamantane skeleton and a component having an iodine atom in the film-forming composition, it is preferable to obtain a film-forming composition that can form films with even higher resolution and even higher sensitivity. In other words, it is more preferable for the film-forming composition to contain a component having both an adamantane skeleton and an iodine atom.

[0044] When the forming composition contains iodine atoms, the total iodine atom content (sum content) in the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) is preferably 2% by mass or more, more preferably 25% by mass or more and 40% by mass or less, and even more preferably 30% by mass or more and 35% by mass or less, based on 100% by mass of the total of the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C). When the iodine atom content is within the above range, the forming composition tends to be able to form films with even higher resolution and even higher sensitivity.

[0045] In the composition for forming, the total iodine content (total content) of the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) is calculated based on the following formula (ii), as an amount relative to 100% by mass of the total of the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C).

[0046]

[0047] Next, we will describe each component contained in the forming composition.

[0048] [Polymer (A)] The composition for polymer formation contains polymer (A). Polymer (A) contains repeating units having acid-dissociable groups. Polymer (A) can be used alone or in combination of two or more types.

[0049] Polymer (A) may be, for example, obtained by polymerizing a compound having a polymerizable unsaturated group, and containing that compound as a repeating unit. Polymer (A) may be obtained by homopolymerizing a compound having an acid-dissociable group and a polymerizable unsaturated group, or by copolymerizing a compound having an acid-dissociable group and a polymerizable unsaturated group with a compound having a polymerizable unsaturated group. Examples of compounds having an acid-dissociable group and a polymerizable unsaturated group include compounds having an acid-dissociable group in the molecule of the compounds exemplified below. Polymers may have substituents and organic groups, for example. Examples of substituents and organic groups include the substituents and organic groups described above.

[0050] Polymerizable unsaturated groups include, for example, groups having double and triple bonds, and chemically reactive groups. Examples of such groups include vinyl, allyl, acryloyl, methacryloyl, styryl, isoprene, butadiene, acrylonitrile, chloroprene, divinyl, fumarate, maleate, vinylidene, methacrylamide, itaconic acid, maleimide, olefin, fluoroolefin, nitroso, acrylamide, crosslinked, enamine, phthalate, isocyanate, aryl, thiol, acrylic acid, sulfone, amide, alkyne, diene, fluoroalkene, nitrile, and phenol groups.

[0051] Examples of polymerizable unsaturated groups include compounds or resins having the above-mentioned groups. Such compounds include, for example, vinyl compounds, monohydric or polyhydric alcohol (meth)acrylates, epoxy (meth)acrylates, urethane acrylates, maleimide compounds, isocyanate compounds, fumarate esters, vinyl ether compounds, allyl compounds, itaconic acid esters, dicyclopentadiene derivatives, phenol resins, vinylpyridine compounds, vinyl carboxylate compounds, diene compounds, alkylphenol ethylene oxide compounds, silicone compounds, maleic acid esters, norbornene derivatives, diacrylate esters, acrylamide derivatives, isocyanate monomers, aryl ethers, siloxane compounds, oxazoline compounds, thiol compounds, divinyl sulfones, naphthalene derivatives, chloroprene derivatives, imide compounds, and benzoxazine resins. These compounds or resins may have substituents or organic groups. Examples of substituents and organic groups include those mentioned above. From the viewpoint of solubility and film-forming properties after polymerization, vinyl compounds with substituents including aryl or alicyclic structures, and (meth)acrylates of monohydric or polyhydric alcohols are preferred.

[0052] Polymers (A) include, for example, polyolefin resins such as polyethylene and polypropylene, polyvinyl chloride, polystyrene, poly(4-hydroxystyrene), poly(norbornene) polymers, polyglycidyl methacrylate, polycarbonate, polyethylene terephthalate, polyurethane, polymethyl methacrylate, polybutadiene, polyacetal, polyethylene naphthalate, liquid crystal polymers, epoxy resins, melamine resins, phenolic resins, novolac resins, amino resins such as urea resins and melamineformaldehyde resins, polyamide resins, polyester resins such as unsaturated polyester resins and alkyd resins, bismaleimide resins, silicone resins, polyurethane resins, polycarbonate resins, polyethylene terephthalate, fluororesins such as polytetrafluoroethylene and vinylidene fluoride, acrylic-based polymers, poly(glycidyl methacrylate), poly(methyl Examples include phenylene sulfide, liquid crystal polymers, polyetherimide, polyether ketone, natural rubber, styrene-butadiene rubber, nitrile rubber, silicone rubber, polyimide, polyphenylene sulfide, polytetrafluoroethylene, polyether ether ketone, nylon, acrylic, polyester, polyurethane elastomer, polylactic acid, polybutylene succinate, polycaprolactone, poly(lactic acid-coglycolic acid), polyvinyl alcohol, polyether urethane, polydimethylsiloxane, polylactic acid-glycolic acid, polythiophene, polyphenylene vinylene, poly(paraphenylene), poly(dimethylsiloxane)-graft-polylactic acid, polyhydroxyalkanoate, polybutylene succinic acid, polyaniline, poly(3,4-ethylenedioxythiophene), polyvinylidene fluoride, cellulose, starch, casein, gelatin, polyalginic acid, and chitosan. These polymers may have substituents or organic groups. Examples of substituents and organic groups include those described above. Alternatively, polymers may be obtained by combining monomer units that constitute these polymers.

[0053] Polymer (A) contains repeating units having at least one acid-dissociable group in its structure. The number of acid-dissociable groups in the monomer unit containing the acid-dissociable group is preferably one to three, and more preferably one to two. By using such a polymer, the forming composition tends to be able to form films with higher resolution and higher sensitivity.

[0054] Polymer (A) preferably contains an adamantane skeleton. When polymer (A) contains an adamantane skeleton, the forming composition tends to be able to form films with higher resolution and higher sensitivity.

[0055] When polymer (A) contains an adamantane skeleton, the total content of adamantane skeletons in polymer (A), with the mass of one adamantane skeleton being 136, is preferably 33% by mass or more, more preferably 33% by mass or more and 50% by mass or less, and even more preferably 34% by mass or more and 40% by mass or less, based on 100% by mass of polymer (A). By including a polymer with an adamantane skeleton content within the above range, the forming composition tends to be able to form films with higher resolution and higher sensitivity.

[0056] In polymer (A), the amount of adamantane skeleton contained in polymer (A) is calculated as the amount per 100% by mass of polymer (A), based on the following formula (iii), with the mass of one adamantane skeleton being 136.

[0057]

[0058] Polymer (A) preferably contains iodine atoms, and more preferably contains an adamantane skeleton and iodine atoms. By using such a polymer, the forming composition tends to be able to form films with higher resolution and higher sensitivity.

[0059] When polymer (A) contains iodine atoms, the iodine atom content (total content) in polymer (A) is preferably 41% by mass or less, and more preferably 33% by mass or more and 36% by mass or less, because a film with higher sensitivity and higher resolution can be formed relative to 100% by mass of polymer (A).

[0060] In polymer (A), the iodine atom content (total content) in polymer (A) is preferably greater than 41% by mass, more preferably greater than 41% by mass and 55% by mass or less, and even more preferably greater than 41% by mass and 49% by mass or less, because this tends to result in the formation of a film with higher resolution and higher sensitivity compared to 100% by mass of polymer.

[0061] In polymer (A), the iodine atom content in polymer (A) is calculated as an amount per 100% by mass of polymer (A) based on the following formula (iv).

[0062]

[0063] The polymer (A) preferably has repeating units represented by formula (1). The polymer (A) may be a homopolymer having repeating units represented by formula (1), or a copolymer containing repeating units represented by formula (1). By using such a polymer (A), the forming composition tends to be able to form films with even higher resolution and even higher sensitivity.

[0064]

[0065] (In formula (1), R １ R represents a hydrogen atom, a methyl group, or a halogen atom. ２ Each independently represents a hydrogen atom, a linear organic group having 1 to 20 carbon atoms, a branched organic group having 3 to 20 carbon atoms, or a cyclic organic group having 3 to 20 carbon atoms; A represents an adamantane group which may have substituents; L represents an ester bond (-COO-), a single bond, or an oxygen atom; n １ n represents 0 or 1. ２represents an integer from 0 to 20, and the symbol * represents the bonding position with an adjacent repeating unit).

[0066] R １ can be a hydrogen atom, a methyl group, or a halogen atom. As the halogen atom, known atoms can be used, and F (fluorine atom), Cl (chlorine atom), Br (bromine atom), I (iodine atom), etc. can be appropriately used. Since the forming composition has better stability of the forming composition and tends to form a film with higher resolution and higher sensitivity, R １ is preferably a hydrogen atom, a methyl group, or a halogen atom. In addition, from the point of having better exposure sensitivity, it is more preferably an iodine atom. Also, since the forming composition can obtain better polymerizability, has better stability of the forming composition, and tends to form a film with higher resolution and higher sensitivity, R １ is more preferably a hydrogen atom or a methyl group.

[0067] R ２ may be a combination of two or more selected from the group consisting of a linear organic group having 1 to 20 carbon atoms, a branched organic group having 3 to 20 carbon atoms, and a cyclic organic group having 3 to 20 carbon atoms.

[0068] R ２ is preferably a hydrogen atom for the purpose of suppressing the increase in the Tg of the lithography film and improving the introduction effect of iodine element. It is also preferably an organic group having 1 or more carbon atoms for the purpose of controlling solubility in a developer or improving acid decomposability. It is also preferably a hydrogen atom for the purpose of suppressing acid decomposability and ensuring solubility in an alkaline developer in particular and suppressing residues.

[0069] R ２ may have a substituent. R ２Examples of substituents include C1-C20, C1-C10, or C1-C6 alkyl groups, which may have substituents; C2-C20, C2-C10, or C2-C6 alkenyl groups, which may have substituents; C2-C20, C2-C10, or C2-C6 alkynyl groups, which may have substituents; C3-C20, C3-C10, or C3-C6 cycloalkyl groups, which may have substituents; C3-C20, C3-C10, or C3-C6 cycloalkenyl groups, which may have substituents; C3-C20, C3-C10, or C3-C6 cycloalkynyl groups, which may have substituents; C5-C20, C5-C10, or C5-C6 aryl groups, which may have substituents; and combinations thereof. Examples of substituents include those mentioned above.

[0070] R ２ Specific examples include, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, eicosyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, cycloicosyl group, adamantyl group, ethylene group, propylene group, butylene group, phenyl group, naphthyl group, anthracene group, phenanthrene group, tetracene group, chrysene group, triphenylene group, pyrene group, benzopyrene group, azulene group, fluorene group, etc., which may contain ether bonds, ketone bonds, or ester bonds.

[0071] The groups illustrated here include isomers. For example, the propyl group includes the n-propyl group and the isopropyl group, and the butyl group includes the n-butyl group, the sec-butyl group, the isobutyl group, and the tert-butyl group.

[0072] A represents an adamantane group which may have a substituent. The substituent preferably has at least one selected from the group consisting of a hydroxy group, a carboxy group, a linear aliphatic hydrocarbon group having 1 to 12 carbon atoms, a branched aliphatic hydrocarbon group having 1 to 12 carbon atoms, an acid dissociable group, and a halogen atom, and more preferably has a hydroxy group. The halogen atom preferably includes an iodine atom. The acid dissociable group preferably includes at least one selected from the group consisting of a carboxylic acid ester group, a group in which a hydroxy group is protected with a substituted methyl group, a group in which a hydroxy group is protected with a 1-substituted ethyl group, a group in which a hydroxy group is protected with a 1-substituted-n-propyl group, and a group in which a hydroxy group is protected with a silyl group, and more preferably includes a carboxylic acid ester group. When the polymer has such a substituent, a film having higher sensitivity tends to be obtained.

[0073] When A has a substituent, the number of substituents is preferably 1 to 4 in total, and more preferably 1 to 3, from the viewpoint of obtaining better resolution. When A has a hydroxy group as a substituent, the number of hydroxy groups is preferably 1 to 3, and more preferably 1 to 2, from the viewpoint of obtaining better sensitivity. When A has a carboxy group as a substituent, the number of carboxy groups is preferably 1 to 2, and more preferably 1, from the viewpoint of obtaining better sensitivity. When A has an alkoxy group as a substituent, the number of alkoxy groups is preferably 1 to 3, and more preferably 1 to 2, from the viewpoint of obtaining better sensitivity. When A has an alkoxycarbonyl group as a substituent, the number of alkoxycarbonyl groups is preferably 1 to 3, and more preferably 1 to 2, from the viewpoint of obtaining better sensitivity.

[0074] L represents an ester bond (—COO—), a single bond, or an oxygen atom. Since it tends to more preferably achieve both higher resolution and higher sensitivity, L is preferably an ester bond (—COO—).

[0075] n １ represents 0 or 1, and is preferably 0.

[0076] n 2 n represents an integer between 0 and 20. 2 The number of iodine atoms is preferably an integer from 1 to 15, more preferably an integer from 1 to 10, even more preferably an integer from 1 to 5, and even more preferably 1 or 2. By including a polymer with iodine atoms in the above range, the forming composition tends to have superior sensitivity and heat resistance, and to be able to form a film with higher resolution and higher sensitivity.

[0077] The repeating unit represented by formula (1) is preferable to the repeating unit represented by formula (3) because it tends to have higher reactivity and reduce roughness during pattern formation.

[0078]

[0079] In formula (3), R １ , R ２ , A, n １ , n ２ This, including its preferred range, is as defined in formula (1) above.

[0080] The repeating unit represented by formula (3) is more preferable to the repeating unit represented by formula (4) because it tends to result in better etching resistance of the lithography film and a reduction in roughness during pattern formation.

[0081]

[0082] In formula (4), R １ , A, n ２ This, including its preferred range, is as defined in formula (1) above.

[0083] The repeating unit represented by equation (3) tends to yield better contrast and thereby reduce roughness, and therefore, the repeating unit represented by equation (5) below is more preferable.

[0084]

[0085] In formula (5), R ２’Each of these independently represents a linear organic group having 1 to 20 carbon atoms, a branched organic group having 3 to 20 carbon atoms, or a cyclic organic group having 3 to 20 carbon atoms, R １ , A, n １ , n ２ This, including its preferred range, is as defined in formula (1) above.

[0086] R ２’ In the following, for linear organic groups having 1 to 20 carbon atoms, branched organic groups having 3 to 20 carbon atoms, and cyclic organic groups having 3 to 20 carbon atoms, R ２ You should refer to that.

[0087] R ２’ It is preferable that the organic group has one or more carbon atoms for the purpose of controlling solubility by the developing solution or for the purpose of improving acid decompositionability.

[0088] The repeating unit represented by equation (1) is more preferably the repeating unit represented by equation (6) because it provides better sensitivity.

[0089]

[0090] In formula (6), R １ , R ２ , A, n １ , n ２ This, including its preferred range, is as defined in formula (1) above.

[0091] The repeating unit represented by equation (1) is more preferably the repeating unit represented by equation (7) because it provides greater stability.

[0092]

[0093] In formula (7), R １ , R ２ , A, n １ , n ２ This, including its preferred range, is as defined in formula (1) above.

[0094] The repeating unit represented by formula (1) is more preferably the repeating unit represented by formula (8) because it provides a higher EUV sensitization effect.

[0095]

[0096] In formula (8), R １ , R ２ , L, n １ , and the symbol * are as defined in formula (1) above, R Ａ Each of these independently represents a hydrogen atom, a linear organic group having 1 to 20 carbon atoms, a branched organic group having 3 to 20 carbon atoms, or a cyclic organic group having 3 to 20 carbon atoms, n １ A represents 1 or 2, n １ B represents 1 or 2, n １ C represents either 0 or 1.

[0097] The repeating unit represented by formula (8) is more preferably the repeating unit represented by formula (8-1), and even more preferably the repeating unit represented by formula (8-2), since an even higher EUV sensitization effect can be obtained.

[0098]

[0099] In formula (8-1), R １ , R ２ , L, n １ , and the symbol * are as defined in formula (1) above, R Ａ Each of these independently represents a hydrogen atom, a linear organic group having 1 to 20 carbon atoms, a branched organic group having 3 to 20 carbon atoms, or a cyclic organic group having 3 to 20 carbon atoms, n １ A represents 1 or 2, n １ B represents 1 or 2, n １ C represents either 0 or 1.

[0100]

[0101] In formula (8-2), R １ , R ２ , L, n １ , and the symbol * are as defined in formula (1) above.

[0102] Specific examples of compounds that give repeating units represented by formula (1) are listed below, but are not limited to these. As compounds that give repeating units represented by formula (1), compounds that give repeating units represented by formula (8) are preferred. Also, in the examples below, R１ R represents a hydrogen atom or a methyl group. Ａ Each of these independently represents a hydrogen atom, a linear organic group with 1 to 20 carbon atoms, a branched organic group with 3 to 20 carbon atoms, or a cyclic organic group with 3 to 20 carbon atoms. Ａ The preferred range is R in equation (1). ２ As defined within the preferred range. Ｂ R represents an alkyl group having 1 to 10 carbon atoms. Examples of alkyl groups having 1 to 10 carbon atoms include R ２ Refer to [this]. Me represents a methyl group. 1-9 Or I 1-10 This indicates that there are 1 to 9 or 1 to 10 iodine atoms bonded to the adamantane group.

[0103]

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113]

[0114]

[0115]

[0116]

[0117]

[0118]

[0119]

[0120] The compound that provides the repeating unit represented by formula (1) preferably includes at least one selected from the group consisting of compounds that provide the repeating unit represented by formulas (9) to (11) below. When these compounds are used, a higher EUV sensitization effect tends to be obtained. The reason for this is not clear, but the inventors speculate that this is because the balance between EUV absorption efficiency and acid generation efficiency becomes more favorable.

[0121]

[0122] The content of polymer (A) is preferably 50 parts by mass or more and 95 parts by mass or less, more preferably 60 parts by mass or more and 90 parts by mass or less, and even more preferably 65 parts by mass or more and 85 parts by mass or less, based on 100 parts by mass of the total of polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) contained in the forming composition. When the content of polymer (A) is within the above range, the forming composition tends to be able to form a film with higher resolution and higher sensitivity.

[0123] (Method for producing compounds that give repeating units represented by formula (1)) Compounds that give repeating units represented by formula (1) (hereinafter also referred to as "compounds that give repeating units") can be synthesized by known methods. Such methods include, but are not limited to, a method that includes a step of reacting a hydroxy compound represented by formula (a) with a (meth)acrylic acid compound represented by formula (b). Furthermore, homopolymers having repeating units represented by formula (1) (hereinafter also simply referred to as "homopolymers") can be obtained, for example, by polymerizing a compound that gives repeating units represented by formula (1) in the presence of a polymerization initiator, if necessary. Examples of compounds that give repeating units represented by formula (1) include compounds obtained by reacting a hydroxy compound represented by formula (a) with a (meth)acrylic acid compound represented by formula (b).

[0124]

[0125] In formula (a), R ２ , A, n１ , n ２ This, including its preferred range, is as defined in formula (1) above.

[0126]

[0127] In formula (b), R １ R is defined in formula (1) above, including its preferred range, and Ｂ This is selected from the group consisting of a hydroxyl group, a halogen atom, and a (meth)acryloyloxy group.

[0128] The hydroxy compound represented by formula (a) is preferably the compound represented by formula (a1).

[0129]

[0130] In formula (a1), A, n ２ This, including its preferred range, is as defined in formula (1) or formula (a).

[0131] Examples of (meth)acrylic acid compounds represented by formula (b) are given below.

[0132]

[0133] Of these (meth)acrylic acid compounds, (meth)acrylic acid chloride is preferred because it exhibits superior reactivity.

[0134] In formula (a) or formula (a1), n ２ n represents an integer between 0 and 20, preferably between 1 and 15, more preferably between 1 and 10, even more preferably between 1 and 5, and even more preferably 1 or 2. ２ When the values ​​fall within the above range, the roughness during pattern formation tends to be reduced further.

[0135] Next, a method for synthesizing compounds that provide repeating units and contain iodine atoms will be described. For example, iodine is introduced into the hydroxy compound represented by formula (a) before reacting it with the (meth)acrylic acid compound represented by formula (b). Such an introduction method may include, for example, a step of introducing iodine into a compound represented by formula (Sa1) or formula (Sa2) to synthesize a hydroxy compound represented by formula (a) containing iodine atoms. When introducing iodine into a compound of formula (Sa2), the process may further include a step of converting the resulting iodine-introduced product into the compound of formula (a).

[0136]

[0137] In formula (Sa1), R ２ , A, n １ This, including its preferred range, is as defined in formula (1) above.

[0138]

[0139] In formula (Sa2), A is as defined in formula (1), including its preferred range. E is a hydrocarbon group having 1 to 30 carbon atoms, having at least one selected from the group consisting of a hydroxyl group, an aldehyde group, an ether group, a thiol group, and an amino group.

[0140] As iodine introduction reactions, the Sandmeyer method, the Halex method, iodine introduction using an iodinating agent or iodine source compound, iodine introduction using an iodinating agent or iodine source compound and an oxidizing agent, iodine introduction using an iodinating agent or iodine source compound and a radical generator, iodine introduction using a system in which catalytic activity is improved by an iodinating agent or iodine source compound and zeolite, etc., and methods of iodination by substitution reaction of functional groups such as hydroxyl groups and halogen groups can be used as appropriate. As iodinating agents, known iodine source compounds such as iodine, potassium iodide, HI (hydrogen iodide), iodine chloride, and N-iodosuccinimide can be used as appropriate. As oxidizing agents, known oxidizing agents such as hydrogen peroxide, iodic acid, periodic acid, and sulfuric acid can be used.

[0141] Next, we will explain a specific method for producing compounds that give repeating units represented by formula (1), using the case where L in formula (1) is an ester bond (compounds that give repeating units represented by formula (3)) as an example.

[0142] As described above, the compound that gives repeating units (preferably the compound that gives repeating units represented by formula (3)) can be produced, for example, by a method that includes the step of reacting a hydroxy compound represented by formula (a) with a (meth)acrylic acid compound represented by formula (b). For the hydroxy compound represented by formula (a), the (meth)acrylic acid compound represented by formula (b) is used in an amount of, for example, 0.5 to 100 molar equivalents, preferably 1 to 20 molar equivalents, and more preferably 1.2 to 5 molar equivalents. This range is preferable because the reaction proceeds sufficiently and the yield of the compound that gives the target repeating units is high.

[0143] Furthermore, when the amount of the (meth)acrylic acid compound represented by formula (b) is 0.5 molar equivalents or more, the hydroxy compound represented by formula (a) tends to convert more favorably, and when the amount of the (meth)acrylic acid compound represented by formula (b) is 100 molar equivalents or less, the amount of impurities remaining in the (meth)acrylic acid compound represented by formula (b) can be suppressed more effectively, thus reducing the likelihood of purity degradation. A solvent can also be used in the step of reacting the hydroxy compound represented by formula (a) with the (meth)acrylic acid compound represented by formula (b).

[0144] As the solvent, commonly available solvents can be used. For example, alcohols, ethers, hydrocarbons, aromatic solvents, halogenated solvents, etc., can be used as appropriate, as long as they do not inhibit the above reaction. Multiple solvents can also be mixed and used, as long as they do not inhibit the above reaction. Since water inhibits the reaction, the use of anhydrous solvents is preferred.

[0145] When producing compounds that provide repeating units, it is preferable to use a solvent with good solubility for the purpose of improving the stability of the materials and the efficiency of the process related to obtaining the final compound from the reaction. Preferred solvents can be indicated by the γP and γH values ​​in the Hansen Solubility Parameters (A User's Handbook, CRC Press, Boca Raton FL, 2007), and γP and γH can be determined from the structure of the compound that provides the repeating units. It is preferable that both γP and γH be low, with a γP value of 6 or less being preferable, more preferably 4 or less, and even more preferably 2 or less. Similarly, a γH value of 6 or less is preferable, more preferably 4 or less, and even more preferably 2 or less.

[0146] Particularly preferred solvents include aromatic solvents such as benzene, toluene, and xylene, or aliphatic hydrocarbon solvents such as hexane, heptane, and octane, or halogenated solvents such as dichloromethane and dichloroethane, which are used as the main solvent.

[0147] The reaction temperature and reaction time in the production of compounds that yield repeating units depend on the substrate concentration (e.g., the concentration of the hydroxy compound represented by formula (a)) and the catalyst used, but generally the reaction can be carried out at a temperature of -20°C to 100°C, for a reaction time of 1 to 10 hours, and under atmospheric pressure, reduced pressure, or increased pressure. Furthermore, the reaction can be carried out by appropriately selecting known methods such as batch, semi-batch, or continuous reactions.

[0148] Furthermore, polymerization inhibitors may be added during the reaction, and commercially available products that are generally available can be used. For example, nitroso compounds such as 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl, N-nitrosophenylhydroxylamine ammonium salt, N-nitrosophenylhydroxylamine aluminum salt, N-nitroso-N-(1-naphthyl)hydroxylamine ammonium salt, N-nitrosodiphenylamine, N-nitroso-N-methylaniline, nitrosonaphthol, p-nitrosophenol, N,N'-dimethyl-p-nitrosoaniline, phenothiazine, methylene blue, sulfur-containing compounds such as 2-mercaptobenzimidazole, N,N'-diphenyl-p-phenylenediamine, and N-phenyl Examples include amines such as -N'-isopropyl-p-phenylenediamine, 4-hydroxydiphenylamine, and aminophenol; quinones such as hydroxyquinoline, hydroquinone, methylhydroquinone, p-benzoquinone, and hydroquinone monomethyl ether; phenols such as p-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, catechol, 3-s-butylcatechol, and 2,2-methylenebis-(6-t-butyl-4-methylphenol); imides such as N-hydroxyphthalimide; oximes such as cyclohexane oxime and p-quinone dioxime; and dialkylthiodipropinates.

[0149] The amount added is, for example, 0.001 to 10 parts by mass, preferably 0.01 to 1 part by mass, per 100 parts by mass of the (meth)acrylic acid compound represented by formula (b).

[0150] The compound yielding repeating units obtained by the above reaction (preferably a compound yielding repeating units represented by formula (3)) can be isolated and purified as a desired high-purity monomer by known purification methods such as filtration, concentration, distillation, extraction, crystallization, recrystallization, column chromatography, activated carbon, etc., or by a combination thereof.

[0151] (Method for producing a homopolymer having a repeating unit represented by formula (1)) A homopolymer having a repeating unit represented by formula (1) (preferably a polymer having a repeating unit represented by formula (3)) can be obtained, for example, by polymerizing a compound that gives the repeating unit represented by formula (1) in the presence of a polymerization initiator as needed.

[0152] (Method for producing copolymers containing repeating units represented by formula (1)) Copolymers containing repeating units represented by formula (1) (hereinafter also simply referred to as "polymers") can be obtained by copolymerizing two or more compounds that give repeating units represented by formula (1), or by copolymerizing one or more compounds that give repeating units represented by formula (1) with other monomers. By polymerizing in this way, copolymers can be formed that contain, for example, at least one group or atom selected from the group consisting of an adamantane group which may have one or more substituents, one or more iodine atoms, one or more hydrophilic groups (e.g., a hydroxyl group, a carboxyl group, and a lactone group), and one or more acid-dissociable groups. A resist composition containing the copolymer as a component of a lithography film-forming composition can achieve high sensitivity in the lithography process and high resolution by expanding the solubility contrast of the lithography film during development.

[0153] Examples of repeating units in copolymers other than the repeating unit represented by formula (1), and compounds that provide such repeating units, include those described in International Publication No. 2016 / 125782 (particularly the compounds that provide repeating units described in paragraphs 0017 to 0018 and paragraphs 0034 to 0039), International Publication No. 2015 / 115613, Japanese Patent Publication No. 2015-117305, International Publication No. 2014 / 175275, International Publication No. 2024 / 005049 (particularly the compounds described in paragraphs 0088 to 0097), Japanese Patent Publication No. 2012-162498, or compounds that provide repeating units represented by formula (C1) and compounds that provide repeating units represented by formula (C2).

[0154]

[0155] In formula (C1), RＣ１１ R represents a hydrogen atom or a methyl group. Ｃ１２ R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Ｃ１３ R Ｃ１３ The group, together with the carbon atom to which it is bonded, represents a cycloalkyl group or heterocycloalkyl group having 4 to 20 carbon atoms, and the dot * indicates the bond site with an adjacent repeating unit. For specific examples of these groups, refer to the groups described herein. Examples of heterocycloalkyl groups having 4 to 20 carbon atoms include azilidinyl group, oxyranyl group, thyranyl group, azetidinyl group, oxetanyl group, thietanyl group, tetrahydrothienyl group, tetrahydrofuranyl group, pyrrolidinyl group, imidazolidinyl group, oxazolidinyl group, pyrazolidinyl group, thiazolidinyl group, tetrahydroisothiazolyl group, tetrahydrooxazolyl group, tetrahydroisoxazolyl group, piperidinyl group, piperazinyl group, tetrahydropyranyl group, tetrahydrothiopyranyl group, morpholinyl group, thiomorpholinyl group, azepanyl group, diazepanyl group, oxepanyl group, azocanyl group, and diazocanyl group.

[0156] Preferably, R Ｃ１２ R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Ｃ１３ R Ｃ１３ Together with the carbon atom to which it is bonded, it forms a cycloalkyl group or heterocycloalkyl group having 4 to 10 carbon atoms. １３ It may have substituents (e.g., oxo groups).

[0157]

[0158] In formula (C2), R Ｃ２１ R represents a hydrogen atom or a methyl group. Ｃ２２ and R Ｃ２３ Each of these independently represents an alkyl group having 1 to 4 carbon atoms, and R Ｃ２４ R represents an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 5 to 20 carbon atoms, which may have a hydroxyl group, a carboxyl group, or an ester group. Ｃ２２ ~R Ｃ２４Two or three of these groups may, together with the carbon atoms to which they are bonded, form an alicyclic structure having 3 to 20 carbon atoms, where * indicates a bond site with an adjacent repeating unit. For specific examples of these groups, refer to the groups described herein.

[0159] Preferably, R Ｃ２２ R represents an alkyl group having 1 to 3 carbon atoms. Ｃ２４ R is a cycloalkyl group having 5 to 10 carbon atoms. Ｃ２２ ~R Ｃ２４ The alicyclic structure formed by the above may include multiple rings, such as adamantyl groups. Furthermore, the alicyclic structure may have substituents (e.g., hydroxyl groups, alkyl groups).

[0160] The compound that gives the repeating unit represented by formula (C2) is not particularly limited, but examples include 2-methyl-2-(meth)acryloyloxyadamantane, 2-ethyl-2-(meth)acryloyloxyadamantane, 2-isopropyl-2-(meth)acryloyloxyadamantane, 2-n-propyl-2-(meth)acryloyloxyadamantane, 2-n-butyl-2-(meth)acryloyloxyadamantane, 1-methyl-1-(meth)acryloyloxycyclopentane, 1-ethyl-1-(meth)acryloyloxycyclopentane, 1-methyl Examples include 1-(meth)acryloyloxycyclohexane, 1-ethyl-1-(meth)acryloyloxycyclohexane, 1-methyl-1-(meth)acryloyloxycycloheptane, 1-ethyl-1-(meth)acryloyloxycycloheptane, 1-methyl-1-(meth)acryloyloxycyclooctane, 1-ethyl-1-(meth)acryloyloxycyclooctane, 2-ethyl-2-(meth)acryloyloxydecahydro-1,4:5,8-dimethanonaphthalene, and 2-ethyl-2-(meth)acryloyloxynorbornane. Commercially available products may be used as these compounds.

[0161] Since the performance of the lithography film-forming composition can be further improved, it is preferable that the copolymer contains at least one repeating unit selected from the group consisting of repeating units represented by formula (3) to repeating units represented by formula (7).

[0162] Examples of copolymers include polymers represented by formulas (AI) to (AIII).

[0163]

[0164] In formula (AI), the composition ratio (molar ratio, a:b:c) of a, b, and c is 30 to 65:5 to 15:25 to 65 (where a + b + c = 100). Preferably, the composition ratio of a, b, and c is 50:10:40 (hereinafter, polymers having this composition ratio will also be referred to as "polymers represented by formula (A1)"), 60:10:30 (hereinafter, polymers having this composition ratio will also be referred to as "polymers represented by formula (A2)"), and 36:9:55 (hereinafter, polymers having this composition ratio will also be referred to as "polymers represented by formula (A3)").

[0165] The polymer represented by formula (AI) may be a block copolymer in which each constituent unit forms an independent block, or a random copolymer in which each constituent unit is independent. The polymer represented by formula (AI) is preferably a random copolymer.

[0166]

[0167] In formula (AII), the composition ratio (molar ratio, a:b) of a and b is 40 to 60:60 to 40 (where a + b = 100). Preferably, the composition ratio of a and b is 50:50 (hereinafter, polymers having this composition ratio will also be referred to as "polymers represented by formula (A4)").

[0168] The polymer represented by formula (AII) may be a block copolymer in which each constituent unit forms an independent block, or a random copolymer in which each constituent unit forms an independent block. The polymer represented by formula (AII) is preferably a random copolymer.

[0169]

[0170] In formula (AIII), the composition ratio (molar ratio, a:b:c) of a, b, and c is 50 to 70:5 to 15:20 to 40 (where a + b + c = 100). Preferably, the composition ratio of a, b, and c is 60:10:30 (hereinafter, polymers having this composition ratio will also be referred to as "polymers represented by formula (A5)").

[0171] The polymer represented by formula (AIII) may be a block copolymer in which each constituent unit forms an independent block, or a random copolymer in which each constituent unit forms an independent block. The polymer represented by formula (AIII) is preferably a random copolymer.

[0172] Since the performance of the lithography film-forming composition can be further improved, the copolymer is preferably at least one selected from the group consisting of polymers represented by formulas (AI) to (AIII), and more preferably at least one selected from the group consisting of polymers represented by formulas (A1) to (A5).

[0173] Next, a method for producing copolymers by polymerization reaction will be described. Polymerization reactions are carried out by dissolving the repeating compound or monomer in a solvent, adding a catalyst, and heating or cooling. Reaction conditions can be arbitrarily set by the type of polymerization initiator, the initiation method (such as heat or light), temperature, pressure, concentration, solvent, and additives. Copolymers can be produced by known methods, such as radical polymerization using radical generators like azobisisobutyronitrile or peroxides, or ionic polymerization using catalysts like alkyllithium or Grignard reagents.

[0174] For the polymerization reaction, commercially available solvents that are generally available can be used. For example, various solvents such as alcohols, ethers, hydrocarbons, and halogenated solvents can be used as appropriate, as long as they do not inhibit the reaction. Multiple solvents can also be mixed and used, as long as they do not inhibit the reaction.

[0175] The copolymer obtained by the polymerization reaction can be purified by known methods. Specifically, this can be done by combining ultrafiltration, crystallization, microfiltration, acid washing, water washing with an electrical conductivity of 10 mS / m or less, and extraction.

[0176] [Photoacid Generator (B)] The forming composition contains a photoacid generator (B). The photoacid generator (B) can be used alone or in combination of two or more types.

[0177] The photoacid generator (B) is not particularly limited as long as it generates acid directly or indirectly by irradiation with any radiation selected from visible light, ultraviolet light, excimer laser, electron beam, extreme ultraviolet (EUV), X-ray, and ion beam. For example, such a photoacid generator (B) can be the one described in International Publication No. 2013 / 024778 and Japanese Patent Application Publication No. 2022-141597.

[0178] The photoacid generator (B) preferably contains an adamantane skeleton. When the photoacid generator (B) contains an adamantane skeleton, the forming composition tends to be able to form films with higher resolution and higher sensitivity.

[0179] When the photoacid generator (B) contains an adamantane skeleton, the total content of adamantane skeletons in the photoacid generator (B), with the mass of one adamantane skeleton being 136, is preferably 5% by mass or more, more preferably 10% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 30% by mass or less, based on 100% by mass of the photoacid generator (B). By including a photoacid generator (B) with an adamantane skeleton content within the above range, the forming composition tends to be able to form films with higher resolution and higher sensitivity.

[0180] In photoacid generator (B), the amount of adamantane skeleton contained in photoacid generator (B) is calculated as the amount per 100% by mass of photoacid generator (B), based on the following formula (v), with the mass of one adamantane skeleton being 136.

[0181]

[0182] The photoacid generator (B) preferably contains an iodine atom, and more preferably contains an adamantane skeleton and an iodine atom. By using such components, the forming composition tends to be able to form films with higher resolution and higher sensitivity.

[0183] Furthermore, if the photoacid generator (B) contains iodine atoms, the total content of iodine atoms in the photoacid generator (B) is preferably 2% by mass or more, more preferably 5% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less, based on 100% by mass of the photoacid generator (B). When the iodine atom content is within the above range, the forming composition tends to be able to form a film with higher resolution and higher sensitivity.

[0184] In photoacid generator (B), the amount of iodine atoms contained in photoacid generator (B) is calculated as an amount per 100% by mass of photoacid generator (B) based on the following formula (vi).

[0185]

[0186] In the film-forming composition, it is preferable that at least one selected from the group consisting of a photoacid generator (B) and an acid diffusion inhibitor (C) described later contains an iodine atom, and more preferably contains an adamantane skeleton and an iodine atom. By using such components, the film-forming composition tends to be able to form films with higher resolution and higher sensitivity.

[0187] Furthermore, when the photoacid generator (B) and / or acid diffusion inhibitor contains iodine atoms, the total iodine atom content (sum content) in the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) is preferably 2% by mass or more, more preferably 2% by mass or more and 40% by mass or less, and even more preferably 3% by mass or more and 32% by mass or less, based on 100% by mass of the total of the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C). By using components with an iodine atom content within the above range, the forming composition tends to be able to form films with higher resolution and higher sensitivity.

[0188] The total iodine atom content in polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) is calculated based on the following formula (vii), as the amount relative to 100% by mass of the total of polymer (A), photoacid generator (B), and acid diffusion inhibitor (C).

[0189]

[0190] Examples of photoacid generators (B) include sulfonium-based photoacid generators, iodonium-based photoacid generators, onium-based photoacid generators, imide-based photoacid generators, phenyloxydiazine-based photoacid generators, nitrobenzyl-based photoacid generators, and benzoin ether-based photoacid generators. From the viewpoint of obtaining better sensitivity, at least one selected from the group consisting of sulfonium-based photoacid generators and iodonium-based photoacid generators is preferred as the photoacid generator (B).

[0191] Examples of sulfonium-based photoacid generators include tris(adamantyl)sulfonium salt, tris(1-adamantylmethyl)sulfonium triflate, tris(1-adamantyl)sulfonium hexafluoroantimonate, tris(phenyl)sulfonium salt having an adamantyl group, adamantyl group-containing sulfonium triflate, iodosulfonium compounds such as tris(phenyliodo)sulfonium salt, tris(2-iodophenyl)sulfonium salt, iodine-substituted triphenylsulfonium salts such as triphenylsulfonium iodide, and iodine-containing sulfonium triflate. Examples include iodoadamantylsulfonium salts such as lat, diiodosulfonium salt, and tris(adamantyliodo)sulfonium salt, iodine-substituted adamantylsulfonium triflate, iodoadamantane group-containing triphenylsulfonium salts such as tris(iodoadamantyl)sulfonium salt, diiodoadamantane-containing sulfonium salt, iodoadamantylphenylsulfonium salt, tris(4-trifluoromethylphenyl)sulfonium triflate, triphenylsulfonium hexafluoroantimonate, and triphenylsulfonium hexafluorophosphate.

[0192] Examples of iodonium-based photoacid generators include diphenyladamantyliodonium salt, (adamantylmethyl)diphenyliodonium triflate, diphenyl(1-adamantyl)iodonium hexafluorophosphate, tris(adamantylmethyl)iodonium salt, (adamantylphenyl)iodonium tosylate, diphenyliodonium hexafluoroantimonate, and diphenyliodonium hexafluorophosphate.

[0193] Examples of onium-based photoacid generators include adamantane-modified derivatives of triphenylsulfonium triflate, adamantyltris(phenyl)onium salt, adamantylphenylonium trifluoromethanesulfonate, adamantyl-substituted diaryliodonium salt, adamantyliodonium triflate, adamantyliodonium hexafluoroantimonate, triphenylsulfonium pentafluoroantimonate, and tris(4-methoxyphenyl)sulfonium triflate.

[0194] Examples of imide-based photoacid generators include adamantyltriphenylsulfonium bis(trifluoromethylsulfonyl)imide, adamantyldiaryliodonium bis(trifluoromethylsulfonyl)imide, adamantylphenylonium bis(trifluoromethylsulfonyl)imide, and nonafluorobis(trifluoromethylsulfonyl)imide.

[0195] Examples of phenyloxydiazine-based photoacid generators include adamantyl-substituted phenyloxydiazine, adamantylphenyloxydiazinebis(trifluoromethylsulfonyl)imide, adamantane-modified phenyloxydiazine, adamantyliodophenyloxydiazine, adamantyliododiarylphenyloxydiazine, adamantyl-substituted iodophenyloxydiazine, and phenyloxydiazine.

[0196] Examples of nitrobenzyl-based photoacid generators include adamantyl nitrobenzyl ether, adamantyl nitrobenzyl carbonate, adamantane-modified nitrobenzyl ester, adamantane-substituted nitrobenzylamine, adamantyliodonitrobenzyl ether, adamantyliodonitrobenzylamine, adamantane-modified iodonitrobenzyl ether derivatives, nitrobenzyl ester, 2-nitrobenzylsulfonic acid, and 4-nitrobenzylsulfonic acid ester.

[0197] Examples of benzoin ether-based photoacid generators include adamantane-1-benzoin ether, adamantane-2-benzoin ether, adamantyloxybenzoin ether, adamantyliodobenzoin ether, benzoiniodoadamantyl ether, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-t-butyl ether, benzoin cyclohexyl ether, benzoin phenyl ether, and benzoin allyl ether.

[0198] Among these, the photoacid generator (B) preferably contains at least one selected from the group consisting of compounds represented by formula (B1) and compounds represented by formula (B2). By using such a photoacid generator, the forming composition tends to be able to form films with even higher resolution and even higher sensitivity.

[0199]

[0200]

[0201] The content of the photoacid generator (B) is preferably 0.001 parts by mass or more and 49 parts by mass or less, more preferably 1 part by mass or more and 40 parts by mass or less, even more preferably 3% by mass or more and 30% by mass or less, and even more preferably 10% by mass or more and 25% by mass or less, based on 100 parts by mass of the total of the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) contained in the forming composition. When the content of the photoacid generator is within the above range, the forming composition tends to be able to form a film with higher resolution and higher sensitivity.

[0202] [Acid diffusion inhibitor (C)] The forming composition contains an acid diffusion inhibitor (C). The acid diffusion inhibitor (C) can be used alone or in combination of two or more types.

[0203] The acid diffusion inhibitor (C) is not particularly limited as long as it controls the diffusion of the acid generated from the photoacid generator (B) by radiation irradiation within the resist film, thereby preventing undesirable chemical reactions in unexposed areas. Using an acid diffusion inhibitor tends to improve the storage stability of the composition. Furthermore, using an acid diffusion inhibitor can improve the resolution of the film formed using the forming composition, and can suppress changes in the line width of the resist pattern due to variations in the pre-irradiation and post-irradiation rest periods, thus resulting in superior process stability.

[0204] For example, the acid diffusion inhibitor (C) described in International Publication No. 2013 / 024778 can be used.

[0205] The acid diffusion inhibitor (C) preferably contains an adamantane skeleton. The inclusion of an adamantane skeleton in the acid diffusion inhibitor (C) tends to enable the formation of a film with higher resolution and higher sensitivity.

[0206] When the acid diffusion inhibitor (C) contains an adamantane skeleton, the total content of adamantane skeletons in the acid diffusion inhibitor (C), with the mass of one adamantane skeleton being 136, is preferably 10% by mass or more, more preferably 20% by mass or more and 70% by mass or less, and even more preferably 30% by mass or more and 60% by mass or less, relative to 100% by mass of the polymer. By including an acid diffusion inhibitor (C) with an adamantane skeleton content within the above range, the forming composition tends to be able to form a film with higher resolution and higher sensitivity.

[0207] In the acid diffusion inhibitor (C), the amount of adamantane skeleton contained in the acid diffusion inhibitor (C) is calculated as the amount per 100% by mass of the acid diffusion inhibitor (C), based on the following formula (viii), with the mass of one adamantane skeleton being 136.

[0208]

[0209] The acid diffusion inhibitor (C) preferably contains an iodine atom, and more preferably contains an adamantane skeleton and an iodine atom. By using such components, the forming composition tends to be able to form films with higher resolution and higher sensitivity.

[0210] Furthermore, if the acid diffusion inhibitor (C) contains iodine atoms, the total amount of iodine atoms contained in the acid diffusion inhibitor (C) is preferably 2% by mass or more, more preferably 2% by mass or more and 40% by mass or less, and even more preferably 3% by mass or more and 32% by mass or less, based on 100% by mass of the total of the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C). When the iodine atom content is within the above range, the forming composition tends to be able to form a film with higher resolution and higher sensitivity.

[0211] In the acid diffusion inhibitor (C), the amount of iodine atoms contained in the acid diffusion inhibitor (C) is calculated as an amount per 100% by mass of the acid diffusion inhibitor (C) based on the following formula (ix).

[0212]

[0213] Examples of acid diffusion inhibitors (C) include radiodegradable basic compounds such as nitrogen atom-containing basic compounds, basic sulfonium compounds, and basic iodonium compounds.

[0214] Examples of nitrogen atom-containing basic compounds include adamantylamine, adamantanylpyridine, imidazole derivatives having an adamantane group, pyridine derivatives having an adamantyl group, adamantyliodoamine, adamantyliodopyridine, adamantyliodoguanidine, triethylamine, dimethylamine, diethylamine, methylamine, dibutylamine, tributylamine, ethylenediamine, benzylamine, pyridine, piperidine, morpholine, morpholine derivatives, N-methylmorpholine, tetramethylethylenediamine, imidazole, 1-methylimidazole, 2-phenylimidazole, aziridine, 1,4-diazabicyclo[2.2.2]octane, and benzylamine derivatives.

[0215] Examples of basic sulfonium compounds include adamantylsulfonium salts, adamantylsulfonium hydroxides, adamantylthiosulfonium compounds, adamantyldisulfonium compounds, adamantyliodosulfonium salts, adamantyliodomethylsulfonium salts, adamantyliodothiosulfonium compounds, adamantyldiiodosulfonium compounds, tris(dimethylsulfonium)methane, dimethylsulfonium salts, dimethylphenylsulfonium salts, trimethylsulfonium iodide, trimethylsulfonium salts, triethylsulfonium salts, methylethylphenylsulfonium salts, dimethylpropylsulfonium salts, diethylsulfonium salts, triphenylsulfonium salts such as the compound represented by formula (10), tris(phenylmethylsulfonium) phosphate, tris(alkylsulfonium) phosphate, dimethylbenzylsulfonium salt, and tris(hydroxyalkylsulfonium) compounds.

[0216] Examples of radiodegradable basic compounds include basic iodonium compounds, radiodegradable phosphonium salts such as triphenylphosphonium salts and tetraphenylphosphonium salts, radiodegradable azo compounds such as azobisisobutyronitrile, radiodegradable carboxylic acid amides such as aziridine derivatives, and radiodegradable diazonium compounds.

[0217] Examples of basic iodonium compounds include adamantaneiodonium salt, adamantyliodonium triflate, diphenyliodonium hexafluorophosphate and diphenyliodonium triflate, other diphenyliodonium salts, phenyl-tetrahydrofurfuryliodonium salt, diphenyliodonium chloride, diphenyliodonium tosylate, triphenyliodonium salt, and bis(4-trifluoromethylphenyl)iodonium salt.

[0218] Among these, the acid diffusion inhibitor (C) preferably contains a compound represented by formula (C1). By using such an acid diffusion inhibitor (C), the forming composition tends to be able to form a film with even higher resolution and even higher sensitivity.

[0219]

[0220] The content of the acid diffusion inhibitor (C) is preferably 0.001 parts by mass or more and 49 parts by mass or less, more preferably 0.01 parts by mass or more and 10 parts by mass or less, even more preferably 0.01 parts by mass or more and 5 parts by mass or less, and even more preferably 0.01 parts by mass or more and 3 parts by mass or less, based on 100 parts by mass of the total of the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) contained in the forming composition. When the content of the acid diffusion inhibitor (C) is within the above range, the forming composition tends to be able to form a film with higher resolution and higher sensitivity.

[0221] [Other Components] The forming composition comprises a polymer (A), a photoacid generator (B), and an acid diffusion inhibitor (C), and may optionally contain other components such as a base material (D), a solvent (S), a base generator (G), and an additive (F). Each component is described below.

[0222] (Substrate (D)) The forming composition may include a substrate (D). "Substrate (D)" means a compound (including resins) other than the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C), which is a substrate applied as a resist for g-ray, i-ray, KrF excimer laser (248 nm), ArF excimer laser (193 nm), extreme ultraviolet (EUV) lithography (13.5 nm), or electron beam (EB) (for example, a substrate for lithography or a substrate for resists). Any of these substrates is not particularly limited and can be used as the substrate (D) in this embodiment.

[0223] Examples of the substrate (D) include phenol novolac resin, cresol novolac resin, hydroxystyrene resin, (meth)acrylic resin, hydroxystyrene-(meth)acrylic copolymer, cycloolefin-maleic anhydride copolymer, cycloolefin, vinyl ether-maleic anhydride copolymer, and inorganic resist materials having metallic elements such as titanium, tin, hafnium, and zirconium, as well as derivatives thereof. Among these, phenol novolac resin, cresol novolac resin, hydroxystyrene resin, (meth)acrylic resin, hydroxystyrene-(meth)acrylic copolymer, and inorganic resist materials having metallic elements such as titanium, tin, hafnium, and zirconium, as well as derivatives thereof, are preferred from the viewpoint of the shape of the resist pattern obtained.

[0224] Examples of derivatives include those with introduced acid-dissociating groups or crosslinking groups. Derivatives with introduced dissociating or crosslinking groups can undergo dissociation or crosslinking reactions in response to light, acid, or other factors.

[0225] (Solvent (S)) The composition for forming the polymer may contain a solvent (S). Any known solvent (S) can be used as appropriate, as long as it is capable of dissolving at least the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C).

[0226] Examples of solvents (S) 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 (PGME) and propylene glycol monoethyl ether; and lactic acid esters such as methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, and n-amyl lactate. Aliphatic carboxylic acid esters such as methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, n-amyl acetate, n-hexyl acetate, methyl propionate, and ethyl propionate; 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, 3-methoxy- Examples of other esters include butyl 3-methylbutyrate, methyl acetoacetate, methyl pyruvate, ethyl pyruvate, etc.; aromatic hydrocarbons such as toluene and xylene; ketones such as acetone, 2-butanone, 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; and lactones such as γ-lactone, but are not particularly limited.

[0227] The solvent (S) is preferably a safe solvent, more preferably at least one selected from PGMEA, PGME, CHN, CPN, 2-heptanone, anisole, butyl acetate, and ethyl lactate, and even more preferably at least one selected from PGMEA, PGME, CHN, CPN, and ethyl lactate. The solvent (S) can be used alone or in combination of two or more.

[0228] In this embodiment, the amounts of solid components and solvent (S) in the forming composition are preferably 1 to 80% by mass of solid components and 20 to 99% by mass of solvent (S) relative to the total mass of solid components and solvent (S), more preferably 1 to 50% by mass of solid components and 50 to 99% by mass of solvent (S), even more preferably 2 to 40% by mass of solid components and 60 to 98% by mass of solvent (S), and even more preferably 2 to 10% by mass of solid components and 90 to 98% by mass of solvent (S). In this specification, "solid components" refers to components other than the solvent contained in the composition of this embodiment.

[0229] (Base Generator (G)) The composition for forming the base may contain a base generator (G). The case where the base generator (G) is a photobase generator will be described below. A photobase generator is a substance that generates a base upon exposure, and does not show activity under normal conditions at room temperature and pressure, but generates a base (basic substance) when exposed to electromagnetic waves and heated as external stimuli.

[0230] The photobase generator is not particularly limited and any known one can be used. Examples of photobase generators include carbamate derivatives, amide derivatives, imide derivatives, α-cobalt complexes, imidazole derivatives, cinnamic acid amide derivatives, oxime derivatives, and the like.

[0231] Examples of basic substances generated from a photobase generator include compounds having an amino group, particularly monoamines, polyamines such as diamines, and amidines. Compounds having an amino group with higher basicity (higher pKa value of the conjugate acid) are preferred because they exhibit superior sensitivity and resolution.

[0232] Examples of photobase generators include base generators having a cinnamic acid amide structure as disclosed in Japanese Patent Publication No. 2009-80452 and International Publication No. 2009 / 123122, base generators having a carbamate structure as disclosed in Japanese Patent Publication No. 2006-189591 and Japanese Patent Publication No. 2008-247747, base generators having an oxime structure or carbamoyl oxime structure as disclosed in Japanese Patent Publication No. 2007-249013 and Japanese Patent Publication No. 2008-003581, and compounds described in Japanese Patent Publication No. 2010-243773, but are not limited to these, and other known base generator structures can be used.

[0233] The photobase generator can be used alone or in combination of two or more types. The content of the photobase 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 particularly preferably 10 to 25% by mass, based on the total mass of the solid components in the forming composition. When the content of the photobase generator is within the above range, there is a tendency for better sensitivity and the formation of patterns with lower edge roughness to occur.

[0234] (Additives (F)) The forming composition may contain, as necessary, one or more additives (F) such as crosslinking agents, dissolution accelerators, dissolution controllers, sensitizers, surfactants, and organic carboxylic acids or phosphorus oxoacids or derivatives thereof.

[0235] In this embodiment, the forming composition may contain one or more crosslinking agents. A crosslinking agent means a compound that can crosslink at least the polymer (A) and, if necessary, the substrate (D). Preferably, the crosslinking agent is an acid crosslinking agent that can intramolecularly or intermolecularly crosslink the polymer (A) and the substrate (D) in the presence of an acid generated from a photoacid generator (B). Examples of such acid crosslinking agents include compounds having one or more groups (hereinafter referred to as "crosslinkable groups") that can crosslink the polymer (A) and the substrate (D).

[0236] Examples of crosslinkable groups include (i) hydroxyalkyl groups such as hydroxy(C1-C6 alkyl groups), C1-C6 alkoxy(C1-C6 alkyl groups), acetoxy(C1-C6 alkyl groups), or groups derived therefrom; (ii) carbonyl groups such as formyl group, carboxy(C1-C6 alkyl groups), or groups derived therefrom; (iii) dimethylaminomethyl group, diethylaminomethyl group, dimethylolaminomethyl group, diethylolaminomethyl group, and diethylaminomethyl Examples of crosslinking agents include nitrogen-containing groups such as hydroxyl groups and morpholinomethyl groups; (iv) glycidyl group-containing groups such as glycidyl ether groups, glycidyl ester groups, and glycidylamino groups; (v) groups derived from aromatic groups such as aryloxy (alkyl groups having 1 to 6 carbon atoms) and aralkyloxy (alkyl groups having 1 to 6 carbon atoms) such as benzyloxymethyl and benzoyloxymethyl groups; and (vi) polymerizable multiple bond-containing groups such as vinyl groups and isopropenyl groups. Preferred crosslinking groups for the crosslinking agent are hydroxyalkyl groups and alkoxyalkyl groups, with alkoxymethyl groups being particularly preferred.

[0237] As a crosslinking agent having a crosslinking group, for example, the acid crosslinking agent described in International Publication No. 2013 / 024778 can be used. The crosslinking agent can be used alone or in combination of two or more types.

[0238] The crosslinking agent content is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 20% by mass or less, based on the total mass of solid components in the forming composition. The lower limit is not particularly limited, but for example, it is 0.001% by mass or more, based on the total mass of solid components in the forming composition.

[0239] A dissolution accelerator is a component that increases the solubility of a solid component in a developer when its solubility is too low, thereby moderately increasing the dissolution rate of the compound during development. Low molecular weight dissolution accelerators are preferred, and examples include low molecular weight phenolic compounds. Examples of low molecular weight phenolic compounds include bisphenols and tris(hydroxyphenyl)methane. These dissolution accelerators can be used individually or in combination of two or more.

[0240] The amount of dissolution accelerator is adjusted as appropriate depending on the type of solid component used, but is preferably 0 to 49% by mass, more preferably 0 to 5% by mass, even more preferably 0 to 1% by mass, and particularly preferably 0% by mass, relative to the total mass of the solid component in the forming composition.

[0241] A dissolution control agent is a component that controls the solubility of solid components in the developer when their solubility is too high, thereby moderately reducing the dissolution rate during development. Preferably, such a dissolution control agent does not undergo chemical changes during processes such as firing, radiation irradiation, and development of the resist film.

[0242] Examples of dissolution control agents include aromatic hydrocarbons such as phenanthrene, anthracene, and acenaphthene; ketones such as acetophenone, benzophenone, and phenylnaphthylketone; and sulfones such as methylphenylsulfone, diphenylsulfone, and dinaphthylsulfone. These dissolution control agents can be used individually or in combination of two or more.

[0243] The amount of the dissolution control agent is adjusted as appropriate depending on the type of compound used, but is preferably 0 to 49% by mass, more preferably 0 to 5% by mass, even more preferably 0 to 1% by mass, and particularly preferably 0% by mass, relative to the total mass of the solid components in the forming composition.

[0244] A sensitizer is a component that absorbs the energy of irradiated radiation and transfers that energy to a photoacid generator (B), thereby increasing the amount of acid produced and improving the apparent sensitivity of the resist. Examples of such sensitizers include, but are not limited to, benzophenones, biacetyls, pyrenes, phenothiazines, and fluorenes. These sensitizers can be used alone or in combination of two or more.

[0245] The amount of sensitizer is adjusted as appropriate depending on the type of compound used, but is preferably 0 to 49% by mass, more preferably 0 to 5% by mass, even more preferably 0 to 1% by mass, and particularly preferably 0% by mass, relative to the total mass of solid components in the forming composition.

[0246] Surfactants are components that improve the coatability and striation properties of the forming composition, as well as the developability of the resist. Surfactants may be anionic surfactants, cationic surfactants, nonionic surfactants, or amphoteric surfactants. Nonionic surfactants are preferred. Nonionic surfactants have good affinity with the solvent used in the manufacture of the forming composition, and can further enhance the effects of the forming composition. Examples of nonionic surfactants include, but are not limited to, polyoxyethylene higher alkyl ethers, polyoxyethylene higher alkylphenyl ethers, and polyethylene glycol higher fatty acid diesters. Commercially available products of these surfactants include, under the trade names listed below, F-Top (manufactured by Gemco), Megafac (manufactured by Dainippon Ink and Chemicals, Inc.), Florad (manufactured by Sumitomo 3M Co., Ltd.), Asahi Guard, Surflon (all manufactured by Asahi Glass Co., Ltd.), Pepol (manufactured by Toho Chemical Industry Co., Ltd.), KP (manufactured by Shin-Etsu Chemical Co., Ltd.), and Polyflow (manufactured by Kyoeisha Oil & Fat Chemical Industry Co., Ltd.).

[0247] The surfactant content is adjusted as appropriate depending on the type of solid component used, but is preferably 0 to 49% by mass, more preferably 0 to 5% by mass, even more preferably 0 to 1% by mass, and particularly preferably 0% by mass, relative to the total mass of the solid component in the forming composition.

[0248] For the purpose of preventing sensitivity degradation or improving resist pattern shape, settling stability, etc., an organic carboxylic acid or phosphorus oxoacid or derivative thereof may be included as an optional component. The organic carboxylic acid or phosphorus oxoacid or derivative thereof may be used in combination with the acid diffusion control agent (C) or used alone. Suitable organic carboxylic acids include, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, and salicylic acid. Suitable phosphorus oxoacids or derivatives thereof include phosphoric acid, di-n-butyl phosphate, diphenyl phosphate and other phosphoric acid derivatives or their esters, phosphonic acid or its ester derivatives, phosphonic acid, dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonic acid, diphenyl phosphonate, dibenzyl phosphonate and other phosphonic acid derivatives or their esters, and phosphinic acid, phenylphosphinic acid and other phosphinic acid derivatives and their ester derivatives, among which phosphonic acid is particularly preferred.

[0249] Organic carboxylic acids or phosphorus oxoacids or derivatives thereof can be used alone or in combination of two or more. The content of organic carboxylic acids or phosphorus oxoacids or derivatives thereof is appropriately adjusted depending on the type of compound used, but is preferably 0 to 49% by mass, more preferably 0 to 5% by mass, even more preferably 0 to 1% by mass, and particularly preferably 0% by mass, relative to the total mass of solid components in the forming composition.

[0250] Furthermore, the forming composition may contain one or more additives other than those mentioned above, as needed. Examples of such additives include dyes, pigments, and adhesive aids. For example, the inclusion of dyes or pigments is preferable because it makes the latent image of the exposed area visible and mitigates the effects of halation during exposure. The inclusion of adhesive aids is also preferable because it improves adhesion to the substrate. Other additives include anti-halation agents, preservative stabilizers, defoamers, shape modifiers, and specifically, 4-hydroxy-4'-methyl chalcone.

[0251] In the forming composition, the total content of additives can be 0 to 99% by mass, preferably 0 to 49% by mass, more preferably 0 to 10% by mass, even more preferably 0 to 5% by mass, even more preferably 0 to 1% by mass, and particularly preferably 0% by mass.

[0252] [Method for preparing a lithography film-forming composition] A lithography film-forming composition can be prepared by combining a polymer (A), a photoacid generator (B), an acid diffusion inhibitor (C), and, if necessary, other components such as a substrate (D), a solvent (S), a base generator (G), and an additive (F), and mixing them using a stirrer or the like. Alternatively, the composition may be prepared by pre-dispersing or mixing it using a dispersion device such as a dissolver, homogenizer, or three-roll mill.

[0253] [Applications of Lithography Film Forming Compositions] The forming compositions can be used for lithography film formation applications, such as resist film formation (i.e., “resist compositions”). Furthermore, the forming compositions can be used for upper layer film formation (i.e., “upper layer film forming compositions”), intermediate layer film formation (i.e., “intermediate layer film forming compositions”), lower layer film formation (i.e., “lower layer film forming compositions”), etc. The forming compositions can form films with high resolution and high sensitivity, and can also impart a good resist pattern shape.

[0254] The forming composition can also be used as an optical component forming composition applying lithography technology. The optical components are used in film and sheet form, and are useful as plastic lenses (prism lenses, lenticular lenses, microlenses, Fresnel lenses, field-of-view control lenses, contrast-enhancing lenses, etc.), phase difference films, electromagnetic shielding films, prisms, optical fibers, solder resists for flexible printed wiring, plating resists, interlayer insulating films for multilayer printed wiring boards, photosensitive optical waveguides, liquid crystal displays, organic electroluminescent (EL) displays, optical semiconductor (LED) elements, solid-state image sensors, organic thin-film solar cells, dye-sensitized solar cells, and organic thin-film transistors (TFTs). The forming composition is particularly suitable for use as a component of solid-state image sensors requiring a high refractive index, such as a filling film and planarization film on a photodiode, a planarization film before and after a color filter, a microlens, a planarization film on a microlens, and a conformal film.

[0255] [Resist film] The resist film of this embodiment is formed from the lithography film formation composition of this embodiment.

[0256] Furthermore, the resist film may be used as a permanent film that remains in the final product after forming a resist pattern as needed. Examples of permanent films include solder resist, packaging materials, underfill materials, package adhesive layers for circuit elements, and adhesive layers between integrated circuit elements and circuit boards in semiconductor devices, and thin-film transistor protective films, liquid crystal color filter protective films, black matrices, and spacers in thin-film displays.

[0257] [Pattern Forming Method] The pattern forming method of this embodiment includes the steps of forming a resist film using the lithography film forming composition of this embodiment, exposing the resist film with extreme ultraviolet light (EUV), and forming a pattern by removing the exposed areas of the resist film with a developer. Such a specific pattern forming method makes it possible to form films with higher resolution and higher sensitivity.

[0258] To form a resist pattern, a resist film is formed by applying a resist composition solution to a substrate such as a silicon wafer, metal, plastic, glass, or ceramic using an appropriate coating method such as a spin coater, dip coater, or roller coater. The film may be pre-treated by heating at a temperature of approximately 50°C to 200°C before exposure through a predetermined mask pattern. The thickness of the coating is, for example, 0.01 to 20 μm, preferably 0.02 to 2 μm. Various wavelengths of light, such as ultraviolet rays and X-rays, can be used for exposure. For example, as a light source, far-ultraviolet rays such as F2 excimer lasers (wavelength 157 nm), ArF excimer lasers (wavelength 193 nm), and KrF excimer lasers (wavelength 248 nm), extreme ultraviolet rays (EUV, wavelength 13.5 nm), X-rays, and electron beams are appropriately selected and used. Extreme ultraviolet rays (EUV, wavelength 13.5 nm) are preferred as the light source for exposure. Furthermore, exposure conditions such as exposure amount are appropriately selected depending on the polymer (A), photoacid generator (B), acid diffusion inhibitor (C), and other components such as the substrate (D), solvent (S), base generator (G), and additives (F) that are added as needed.

[0259] In this embodiment, in order to stably form high-precision fine patterns, it is preferable to perform a heat treatment at a temperature of 50 to 200°C for 30 to 600 seconds after exposure. When the heating temperature is 50°C or higher, variations in sensitivity depending on the type of substrate tend to be more effectively suppressed. Furthermore, when the heating time is 30 seconds or longer, the solubility of the resist composition in the developer tends to be better.

[0260] Subsequent development can be carried out using known methods, such as the dip method, paddle method, and spray method, which can be used as desired. It is preferable to use an alkaline developer. A predetermined resist pattern is formed by developing with the alkaline developer under conditions of 10 to 50°C for 10 to 200 seconds, preferably 20 to 25°C for 15 to 90 seconds.

[0261] It is preferable to rinse after development. Rinsing is an operation in which the developed wafer is washed with a rinsing solution, and known methods can be used. Such methods may include, for example, the dip method, the paddle method, and the spray method. Rinsing is usually performed at 10 to 50°C for 10 to 200 seconds, preferably at 20 to 25°C for 20 to 120 seconds.

[0262] As the alkaline developer, an alkaline aqueous solution is typically used, prepared by dissolving alkaline compounds such as alkali metal hydroxides, aqueous ammonia, alkylamines, alkanolamines, heterocyclic amines, tetraalkylammonium hydroxides such as tetramethylammonium hydroxide (TMAH), choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene in an alkaline aqueous solution at a concentration of 1 to 10% by mass, preferably 1 to 3% by mass. Furthermore, water-soluble organic solvents and surfactants may be added to the alkaline aqueous developer as appropriate.

[0263] In this embodiment, in order to stably form high-precision fine patterns, after exposure and PEB, a developing process can be performed with a developer mainly composed of an organic solvent to form a resist pattern. Various organic solvents are widely used as the organic solvent for the developer, but for example, solvents such as ester solvents, ketone solvents, alcohol solvents, ether solvents, amide solvents, and hydrocarbon solvents can be used. Among these, it is preferable that the developer contains at least one solvent selected from ester solvents, ketone solvents, alcohol solvents, and ether solvents.

[0264] Examples of ester solvents include methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, propyl acetate, isopropyl acetate, amyl acetate (pentyl acetate), isoamyl acetate (isopentyl acetate, 3-methylbutyl acetate), 2-methylbutyl acetate, 1-methylbutyl acetate, hexyl acetate, isohexyl acetate, heptyl acetate, octyl acetate, ethyl methoxyethyl acetate, ethoxyethyl acetate, propylene glycol monomethyl ether acetate (PGMEA; also known as 1-methoxy-2-acetoxypropane), ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monophenyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monopropyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monophenyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, 2-methoxybutyl acetate 3-Methoxybutyl acetate, 4-Methoxybutyl acetate, 3-Methyl-3-Methoxybutyl acetate, 3-Ethyl-3-Methoxybutyl acetate, Propylene glycol monoethyl ether acetate, Propylene glycol monopropyl ether acetate, 2-Ethoxybutyl acetate, 4-Ethoxybutyl acetate, 4-Propoxybutyl acetate, 2-Methoxypentyl acetate, 3-Methoxypentyl acetate, 4-Methoxypentyl acetate, 2-Methyl-3-Methoxypentyl acetate, 3-Methyl-3 - Methoxypentyl acetate, 3-methyl-4-methoxypentyl acetate, 4-methyl-4-methoxypentyl acetate, propylene glycol diacetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, propyl lactate, ethyl carbonate, propyl carbonate, butyl carbonate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, butyl pyruvate, methyl acetoacetate, ethyl acetoacetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, butyl propionate,Examples include isobutyl propionate, pentyl propionate, hexyl propionate, heptyl propionate, butyl butanoate, isobutyl butanoate, pentyl butanoate, hexyl butanoate, isobutyl isobutanoate, propyl pentanoate, isopropyl pentanoate, butyl pentanoate, pentyl pentanoate, ethyl hexanoate, propyl hexanoate, butyl hexanoate, isobutyl hexanoate, methyl heptanoate, ethyl heptanoate, propyl heptanoate, cyclohexyl acetate, cycloheptyl acetate, 2-ethylhexyl acetate, cyclopentyl propionate, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, methyl-3-methoxypropionate, ethyl-3-methoxypropionate, ethyl-3-ethoxypropionate, and propyl-3-methoxypropionate. Among these, butyl acetate, amyl acetate, isoamyl acetate, 2-methylbutyl acetate, 1-methylbutyl acetate, hexyl acetate, pentyl propionate, hexyl propionate, heptyl propionate, methyl hydroxyisobutyrate, or butyl butanoate are preferably used, and butyl acetate, isoamyl acetate, and methyl hydroxyisobutyrate are particularly preferred.

[0265] Examples of ketone solvents include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 2-heptanone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone, isophorone, propylene carbonate, and γ-butyrolactone. Among these, 2-heptanone is preferred.

[0266] Examples of alcohol-based solvents include methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, 3-methyl-1-butanol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-decanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, 3-methyl-1-butanol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 1-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, 3-methyl-1-butanol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 1-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, 3-methyl-1-butanol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 1-hexanol, 11-hexanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, 3-methyl-1-butanol, tert-butyl alcohol, 1 3-Pentanol, Cyclopentanol, 2,3-Dimethyl-2-Butanol, 3,3-Dimethyl-2-Butanol, 2-Methyl-2-Pentanol, 2-Methyl-3-Pentanol, 3-Methyl-2-Pentanol, 3-Methyl-3-Pentanol, 4-Methyl-2-Pentanol, 4-Methyl-3-Pentanol, Cyclohexanol, 5-Methyl-2-Hexanol, 4-Methyl-2-Hexanol, 4,5-Dimethyl-2-Hexanol, 6-Methyl-2-Hexanol Examples include alcohols (monohydric alcohols) such as butanol, 7-methyl-2-octanol, 8-methyl-2-nonanol, 9-methyl-2-decanol, and 3-methoxy-1-butanol; glycol-based solvents such as ethylene glycol, diethylene glycol, and triethylene glycol; glycol ether-based solvents containing hydroxyl groups such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether (PGME; also known as 1-methoxy-2-propanol), diethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methoxymethyl butanol, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and propylene glycol monophenyl ether. Among these, glycol ether-based solvents are preferred.

[0267] Examples of ether-based solvents include, in addition to the glycol ether solvents containing the hydroxyl group mentioned above, glycol ether solvents that do not contain a hydroxyl group, such as propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether; aromatic ether solvents such as anisole and phenethole; and dioxane, tetrahydrofuran, tetrahydropyran, perfluoro-2-butyltetrahydrofuran, perfluorotetrahydrofuran, 1,4-dioxane, and isopropyl ether. Among these, glycol ether solvents and aromatic ether solvents such as anisole are preferred.

[0268] Examples of amide solvents include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, hexamethylphosphoric triamide, and 1,3-dimethyl-2-imidazolidinone.

[0269] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as pentane, hexane, octane, nonane, decane, dodecane, undecane, hexadecane, 2,2,4-trimethylpentane, 2,2,3-trimethylhexane, perfluorohexane, and perfluoroheptane; and aromatic hydrocarbon solvents such as toluene, xylene, ethylbenzene, propylbenzene, 1-methylpropylbenzene, 2-methylpropylbenzene, dimethylbenzene, diethylbenzene, ethylmethylbenzene, trimethylbenzene, ethyldimethylbenzene, and dipropylbenzene.

[0270] Furthermore, unsaturated hydrocarbon solvents can also be used as hydrocarbon solvents, such as octene, nonene, decene, undecene, dodecene, and hexadecene. The number of double or triple bonds in the unsaturated hydrocarbon solvent is not particularly limited, and they may be located at any position in the hydrocarbon chain. Also, if the unsaturated hydrocarbon solvent has double bonds, the cis and trans isomers may be mixed.

[0271] Furthermore, in the case of aliphatic hydrocarbon solvents, which are hydrocarbon solvents, a mixture of compounds with the same number of carbon atoms but different structures may be used. For example, when decane is used as the aliphatic hydrocarbon solvent, compounds with the same number of carbon atoms but different structures, such as 2-methylnonane, 2,2-dimethyloctane, 4-ethyloctane, and isooctane, may be included in the aliphatic hydrocarbon solvent.

[0272] Furthermore, the compounds with the same number of carbon atoms but different structures may include only one type, or multiple types as described above.

[0273] Basic compounds, water-soluble organic solvents, and surfactants may be added to the developing solution consisting of the above-mentioned organic solvent as appropriate.

[0274] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited in any way by these examples.

[0275] [Measurement Method] (1) Structure of Compounds and Polymers The structures of compounds and polymers were determined using a Bruker Advance600II spectrometer under the following conditions: １ This was confirmed by 1H-NMR measurement. Frequency: 600 MHz Solvent: CDCl ３ , or d6-DMSO Internal standard: TMS Measurement temperature: 23°C

[0276] (2) Weight-average molecular weight (Mw) and dispersion (Mw / Mn) of polymers The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polymers were measured by gel permeation chromatography (GPC) using a Showa Denko® GPC-101 (product name) under the following conditions. The dispersion (Mw / Mn) was calculated from Mw and Mn. (Conditions) Flow rate: 1 mL / min Column: Shodex® GPC KF-80M (product name) x 3 Column temperature: 40°C Detector: RI (Refractory Index) Detector standard material: Polystyrene

[0277] [(A) Polymer] (Synthesis Example 1) Synthesis of MAC-ADI4H4M 3.0 g (18.0 mmol) of 5-hydroxy-2-adamantanone was dissolved in 50 mL of chloroform, and 18.05 g (90.0 mmol) of trimethylsilyl iodide was added and the mixture was stirred at 50°C for 6 hours to allow it to react. After the reaction, water was added to wash the mixture, and the organic layer was concentrated and then separated and purified by column chromatography to obtain 3.2 g (11.5 mmol) of 5-iodo-2-adamantanone represented by the following formula.

[0278]

[0279] 2.76 g (10.0 mmol) of 5-iodo-2-adamantanone was dissolved in 30 mL of tetrahydrofuran at 0°C, and methyllithium diethyl ether solution (1.6 mol / L, 10 mL, 16.0 mmol) was added dropwise over 20 minutes at 0°C to 10°C, followed by a reaction for 1 hour. After the reaction, 30 mL of saturated ammonium chloride aqueous solution and 30 mL of water were added at 0°C to quench the mixture, and it was extracted with dichloromethane. The organic layer was concentrated and then separated and purified by column chromatography to obtain 1.92 g of 1-iodo-4-methyl-4-hydroxyadamantane, represented by the following formula.

[0280]

[0281] 2.92 g (10 mmol) of 1-iodo-4-methyl-4-hydroxyadamantane was dissolved in chloroform, and 0.96 g (12 mmol) of pyridine was added under ice cooling. Subsequently, 1.25 g (12 mmol) of methacrylate chloride was added dropwise. The mixture was then stirred under ice cooling for 1 hour and then at room temperature for 3 hours to allow the reaction to proceed. After the reaction was complete, water was added to the reaction solution, and it was washed with saturated sodium bicarbonate aqueous solution. Sodium sulfate was added to the organic phase and dried, and after concentration, the solution was purified by column chromatography to obtain 3.1 g of the target product MAC-ADI4H4M shown below.

[0282] When the obtained compound (MAC-ADI4H4M) was subjected to NMR measurement under the above measurement conditions, the following peaks were detected, confirming that it has the chemical structure shown in the following formula (MAC-ADI4H4M): δ (ppm) (d-DMSO): 6.4-6.5 (2H, =CH２ ), 1.2 to 2.4 (19H, Ad-H, Ad-CH ３ , -C(CH ３ ) = C)

[0283]

[0284] (Synthesis Example 2) Synthesis of MAC-ADIOOH 2.3 g (12.5 mmol) of 1,3,5-adamantanetriol (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was dissolved in 100 mL of toluene, and 28.1 g (125 mmol) of 57% aqueous hydrogen iodide solution was added. The mixture was stirred at 80°C for 13 hours and the reaction was carried out. After the reaction, water was added and the mixture was washed with sodium bicarbonate. The organic layer was concentrated and then separated and purified by column chromatography to obtain 0.9 g of 3-iodo-1,5-dihydroxyadamantane, represented by the following formula.

[0285]

[0286] 4.04 g (10 mmol) of 3-iodo-1,5-dihydroxyadamantane was dissolved in chloroform, and 0.96 g (12 mmol) of pyridine was added under ice cooling. Subsequently, 1.25 g (12 mmol) of methacrylate chloride was added dropwise. The mixture was then stirred under ice cooling for 1 hour and then at room temperature for 3 hours to allow the reaction to proceed. After the reaction was complete, water was added to the reaction solution, and it was washed with saturated sodium bicarbonate aqueous solution. Sodium sulfate was added to the organic phase and dried, and after concentration, the solution was purified by column chromatography to obtain 3.5 g of the target product MAC-ADIOOH shown below.

[0287] When the obtained compound (MAC-ADIOOH) was subjected to NMR measurement under the above measurement conditions, the following peak was detected, confirming that it has the chemical structure shown in the following formula (MAC-ADIOOH): δ (ppm) (d-DMSO): 6.4-6.5 (2H, =CH ２ ), 4.5 (1H, -OH), 1.4-3.1 (14H, Ad-H, -C(CH ３ ) = C)

[0288]

[0289] (Synthesis Example A1) As the monomer (raw material) for synthesizing polymer A1 represented by formula (A1), 4.7 g of MAC-ADI4H4M (MAC-ADI4H4M) obtained in Synthesis Example 1, 0.6 g of 4-hydroxystyrene (pHS), and 2.0 g of MAC-ADIOH (MAC-ADIOH) obtained in Synthesis Example 2 were dissolved in 45 mL of tetrahydrofuran, and 0.20 g of azobisisobutyronitrile was added. After refluxing for 12 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated resin was filtered and dried under reduced pressure to obtain polymer A1 represented by the following formula (A1) in the form of a white powder. The weight-average molecular weight (Mw) of this resin was 13000, and the degree of dispersion (Mw / Mn) was 2.0. １３ ¹³C-NMR measurements revealed that the composition ratio (molar ratio) in the following formula (A1) was a:b:c = 50:10:40. Note that formula (A1) is a simplified representation to show the ratio of each constituent unit; however, polymer A1 is not a block copolymer where each constituent unit forms an independent block. For styrene monomers, the molar ratio was determined based on the integral ratio of the carbon at the base of the benzene ring, and for methacrylate monomers (5-iodo-2-methyl-2-adamantyl methacrylate and 5-iodo-3-hydroxy-2-adamantyl methacrylate), it was determined based on the integral ratio of the carbonyl carbon of the ester bond. Table 1 shows the types, ratios, and composition ratios of each monomer in the polymer obtained in Synthesis Example A1. Similarly, Table 1 shows the types, ratios, and composition ratios of each monomer in the polymers obtained in the examples described below.

[0290]

[0291] (Synthesis Examples A2 and A3) Synthesis of polymers A2 and A3 represented by formulas (A2) and (A3) Polymers A2 and A3 represented by formulas (A2) and (A3) were obtained by the method of Synthesis Example A1, except that the amounts of MAC-ADI4H4M (MAC-ADI4H4M) obtained in Synthesis Example 1, 4-hydroxystyrene (pHS), and MAC-ADIOH (MAC-ADIOH) obtained in Synthesis Example 2 were as shown in Table 1 below. Polymers A2 and A3 represented by formulas (A2) and (A3) were obtained by the method of Synthesis Example A1, with different composition ratios from the polymer represented by formula (A1). As shown in Table 1, １３C-NMR measurements revealed that the composition ratio (molar ratio) in equation (A2) was a:b:c = 60:10:30. Furthermore, the composition ratio (molar ratio) in equation (A3) was a:b:c = 36:9:55.

[0292] (Synthesis Example A4) Synthesis of polymer A4 represented by formula (A4) Polymer A4 represented by the following formula (A4) was obtained by the method described in Synthesis Example A1, except that 4-hydroxystyrene (pHS) was not included. As shown in Table 1, １３ C-NMR measurements revealed that the composition ratio (molar ratio) in equation (A4) was a:b = 50:50.

[0293]

[0294] (Synthesis Example A5) As the monomer (raw material) for synthesizing polymer A5 represented by formula (A5), 1.9 g of t-butyl methacrylate (BMA), 2.3 g of γ-butyrolactone methacrylate (BLMA), and 1.8 g of 4-hydroxystyrene (pHS) were dissolved in 45 mL of tetrahydrofuran, and 0.20 g of azobisisobutyronitrile was added. After refluxing for 12 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated resin was filtered and dried under reduced pressure to obtain polymer A5 represented by the following formula (A5) in the form of a white powder. The weight-average molecular weight (Mw) of this resin was 12000, and the degree of dispersion (Mw / Mn) was 2.1. １３ C-NMR measurements revealed that the composition ratio (molar ratio) in the following formula (A5) was a:b:c = 60:10:30.

[0295]

[0296]

[0297] [(B) Photoacid Generator] The following was used as the photoacid generator (B): • Compound B1 represented by formula (B1) (manufactured by Midori Chemical Co., Ltd.)

[0298]

[0299] Compound B2, represented by formula (B2), was synthesized based on the following scheme 1.

[0300]

[0301]

[0302] Compound B3, represented by formula (B3), was synthesized based on the following scheme 2.

[0303]

[0304]

[0305] [(C) Acid Diffusion Inhibitor] The following was used as the acid diffusion inhibitor (C): • Compound C1 represented by formula (C1) (manufactured by Midori Chemical Co., Ltd.)

[0306]

[0307] [Examples 1-9 and Comparative Example 1] [Preparation of Lithography Film Forming Compositions] Polymers A1-A5 were used as polymers (A), compounds B1-B3 as photoacid generators (B), compound C1 as an acid diffusion inhibitor (C), and PGMEA (propylene glycol monomethyl ether acetate) and PGME (propylene glycol monomethyl ether) as solvents (S), respectively, in the amounts shown in Table 2 below to prepare the lithography film forming compositions (solutions) of Examples 1-13 and Comparative Example 1.

[0308]

[0309] [Evaluation] The following evaluations were performed using the polymers A1 to A5, compounds B1 to B3, compound C1, and the lithography film-forming compositions of Examples 1 to 13 and Comparative Example 1. The results are shown in Table 3.

[0310] (1) Adamantane skeleton and iodine atom content In the lithography film-forming compositions of Examples 1 to 13 and Comparative Example 1, the adamantane skeleton content (mass%) and the iodine atom content (mass%) were calculated by the following methods, respectively. In Table 3, the adamantane skeleton is denoted as Ad and the iodine atom as I.

[0311] - Polymer (A) The amount of adamantane skeleton contained in polymer (A) (mass%) was calculated based on formula (iii) above, assuming a mass of 136 per adamantane skeleton, as the amount per 100 mass% of polymer (A). The amount of iodine atoms contained in polymer (A) was calculated based on formula (iv) above, as the amount per 100 mass% of polymer (A).

[0312] - Photoacid Generator (B) The amount of adamantane skeleton contained in photoacid generator (B) was calculated based on formula (v) above, assuming a mass of 136 per adamantane skeleton, as the amount per 100% by mass of photoacid generator (B). The amount of iodine atoms contained in photoacid generator (B) was calculated based on formula (vi) above, as the amount per 100% by mass of photoacid generator (B).

[0313] - Acid diffusion inhibitor (C) The amount of adamantane skeleton contained in acid diffusion inhibitor (C) was calculated based on formula (viii) above, assuming a mass of 136 per adamantane skeleton, as the amount per 100% by mass of acid diffusion inhibitor (C). In addition, the amount of iodine atoms contained in acid diffusion inhibitor (C) was calculated based on formula (ix) above, as the amount per 100% by mass of acid diffusion inhibitor (C).

[0314] (2) Content of total adamantane skeleton and total iodine atoms in polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) In the lithography film-forming compositions of Examples 1 to 13 and Comparative Example 1, the content of total adamantane skeleton (mass%) and total iodine atoms (mass%) in polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) were calculated by the following methods. In Table 3, the adamantane skeleton is denoted as Ad and iodine atoms as I. Also, 100% by mass of the total of polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) is denoted as "(A) + (B) + (C)".

[0315] - The total adamantane skeleton content (total content, mass%) in the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) was calculated based on the above formula (i), assuming a mass of 136 per adamantane skeleton, as the amount relative to 100% mass of the total of polymer (A), photoacid generator (B), and acid diffusion inhibitor (C).

[0316] - The total iodine atom content (total content, mass%) of the polymer (A), photoacid generator (B), and acid diffusion inhibitor (C) was calculated based on formula (ii) above, as the amount relative to 100 mass% of the total of polymer (A), photoacid generator (B), and acid diffusion inhibitor (C).

[0317] (3) EUV sensitivity evaluation by TMAH aqueous solution development Each of the lithography film-forming compositions (solutions) of Examples 1 to 13 and Comparative Example 1 was applied to a silicon wafer and baked at 110°C for 60 seconds to form a photoresist layer (resist film) with a thickness of 100 nm. Then, an extreme ultraviolet (EUV) exposure system "EUVES-7000" (product name, manufactured by Lithotech Japan Co., Ltd.) was used to expose the film at 1 mJ / cm². ２ From 1 mJ / cm ２ 80 mJ / cm ２ After performing maskless shot exposure with increasing exposure, the wafer was baked (PEB) at 110°C for 90 seconds and developed with a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution for 60 seconds to obtain a wafer with 80 shot exposures. For each shot exposure area obtained, the film thickness was measured using an optical interferometer "VM3200" (product name, manufactured by SCREEN Semiconductor Solutions Co., Ltd.), and profile data of film thickness against exposure was obtained. The exposure value at which the slope of film thickness variation with respect to exposure was largest was set to the sensitivity value (mJ / cm²). ２ ) was calculated as follows.

[0318] (4) Evaluation of EB resolution by TMAH aqueous solution development Each of the lithography film-forming compositions (solutions) of Examples 1 to 13 and Comparative Example 1 was applied to a silicon wafer and baked at 110 to 130°C for 60 seconds to form a photoresist layer (resist film) with a thickness of 100 nm. Next, the wafers were exposed with an electron beam lithography system "ELS-7500" (product name, manufactured by Elionix Co., Ltd., 50 keV), baked at 115°C for 90 seconds (PEB), and developed with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution for 60 seconds to obtain a positive-type line and space pattern. The smallest half and pitch size for which the pattern could be obtained was defined as the resolution (nmHP).

[0319]

[0320] Table 3 shows that the lithography film-forming composition of this embodiment has superior EUV sensitivity and EB sensitivity. Therefore, it was found that by applying the forming composition to lithography film-forming applications and resist film-forming applications, films with high resolution and high sensitivity can be formed.

Claims

A lithography film-forming composition comprising a polymer (A), a photoacid generator (B), and an acid diffusion inhibitor (C), The polymer (A) contains repeating units having acid-dissociable groups, A lithography film-forming composition comprising at least one selected from the group consisting of the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C), having an adamantane skeleton. 　 The polymer (A) contains an adamantane skeleton, The lithography film-forming composition according to claim 1, wherein the content of adamantane skeletons in the polymer (A), when the mass of one adamantane skeleton is 136, is 33% by mass or more with respect to 100% by mass of the polymer (A). 　 The lithography film-forming composition according to claim 1, wherein the polymer (A) has repeating units represented by formula (1). (In formula (1), R １ This represents a hydrogen atom, a methyl group, or a halogen atom. R ２ Each of these independently represents a hydrogen atom, a linear organic group having 1 to 20 carbon atoms, a branched organic group having 3 to 20 carbon atoms, or a cyclic organic group having 3 to 20 carbon atoms. A represents an adamantane group which may have substituents. L represents an ester bond (-COO-), a single bond, or an oxygen atom. n １ It represents 0 or 1, n ２ This represents an integer from 0 to 20, The symbol * indicates a connection point with an adjacent repeating unit. 　 The lithography film-forming composition according to claim 3, wherein the repeating unit represented by formula (1) is the repeating unit represented by formula (8). (In formula (8), R １ , R ２ , L, n １ The symbols * and * are defined in formula (1) above, R Ａ Each of these independently represents a hydrogen atom, a linear organic group having 1 to 20 carbon atoms, a branched organic group having 3 to 20 carbon atoms, or a cyclic organic group having 3 to 20 carbon atoms. n １ A represents 1 or 2, n １ B represents either 1 or 2. n １ C represents either 0 or 1. 　 The lithography film-forming composition according to claim 1, wherein the total amount of adamantane skeletons contained in the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C), when the mass of one adamantane skeleton is 136, is 28% by mass or more with respect to the total mass of the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C) of 100% by mass. 　 The polymer (A) contains iodine atoms, and the amount of iodine atoms contained in the polymer (A) is 41% by mass or less relative to 100% by mass of the polymer (A). At least one selected from the group consisting of the photoacid generator (B) and the acid diffusion inhibitor (C) contains an iodine atom, The lithography film-forming composition according to claim 1, wherein the total iodine atom content in the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C) is 2% by mass or more with respect to 100% by mass of the total of the polymer (A), the photoacid generator (B), and the acid diffusion inhibitor (C). 　 The polymer (A) contains iodine atoms, The lithography film-forming composition according to claim 1, wherein the iodine atom content in the polymer (A) exceeds 41% by mass relative to 100% by mass of the polymer (A). 　 The lithography film-forming composition according to claim 1, wherein the photoacid generator (B) has an adamantane skeleton. 　 The lithography film-forming composition according to claim 1, wherein the acid diffusion inhibitor (C) has an adamantane skeleton. 　 A resist film formed from a lithography film-forming composition according to any one of claims 1 to 9. 　 A step of forming a resist film using a lithography film-forming composition according to any one of claims 1 to 9, A step of exposing the resist film using extreme ultraviolet (EUV) light, A step of removing the exposed areas of the resist film using a developer to form a pattern, A pattern formation method, including the following.

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