Radiation-sensitive composition, intermediate composition for radiation-sensitive composition, and method for forming resist pattern

Abstract

Provided is a radiation-sensitive composition that is highly sensitive to radiation and exhibits good CDU performance, while being guaranteed to be stable in storage.　A radiation-sensitive composition according to the present invention contains an acid-cleavable-group-containing resin (A) and an acid additive (C). The acid-cleavable-group-containing resin (A) satisfies one or more of requirement 1A and requirement 1B. The acid additive (C) satisfies at least one of requirement c1 and requirement c2 and has a pKa of 2.8 or less and a boiling point or decomposition temperature of 160°C or higher.　Requirement 1A: the acid-cleavable-group-containing resin (A) further contains a structural unit derived from a radiation-sensitive onium salt (B) having a specific iodonium cation. Requirement 1B: the acid-cleavable-group-containing resin (A) further contains a non-polymeric radiation-sensitive onium salt (B) having a specific iodonium cation. Requirement c1: the acid additive has two or more groups selected from the group consisting of -COOH, -OH and -NHR. Requirement c2: the acid additive has a phosphonic acid group.

Description

Radiation-sensitive composition, intermediate composition for radiation-sensitive composition, and method for forming a resist pattern.

[0001] The present invention relates to a radiation-sensitive composition, an intermediate composition for a radiation-sensitive composition, and a method for forming a resist pattern.

[0002] In lithography technology, which is used in the manufacturing processes of various electronic devices such as semiconductor devices and liquid crystal devices, a radiation-sensitive composition is irradiated with far ultraviolet light such as an ArF excimer laser, extreme ultraviolet (EUV), or an electron beam to generate acid in the exposed area. A chemical reaction involving the generated acid creates a difference in the dissolution rate in the developer between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

[0003] With the miniaturization of various electronic device structures, there is a demand for further miniaturization of resist patterns in lithography processes. In addition, in response to the demand for further miniaturization of resist patterns, various studies are being conducted to improve the resolution of radiation-sensitive compositions used in microfabrication by lithography and the shape of the resist patterns (see, for example, Patent Document 1). Patent Document 1 discloses that by incorporating a salt consisting of a sulfonic acid anion having a substructure in which a halogen atom or haloalkyl group is bonded to a benzene ring, and a cation, into the resist composition, a resist pattern can be formed with good CDU (Critical Dimension Uniformity).

[0004] Japanese Patent Publication No. 2023-36004

[0005] In recent years, there has been a rapid advance in further miniaturization of resist patterns, with attempts being made to form patterns with line widths of 50 nm or less, for example. Radiation-sensitive compositions used in forming resist patterns are required to exhibit good CDU performance and high sensitivity even when forming such fine resist patterns.

[0006] Regarding the improvement of the sensitivity of resist compositions, it is believed that introducing a radiation-sensitive onium salt consisting of an iodonium cation and an organic anion into the resist composition can increase the absorption efficiency of radiation (especially EUV), thereby improving the sensitivity of the resist composition. However, onium salts containing an iodonium cation, while highly sensitive, have inferior storage stability compared to sulfonium cations, which are widely used as cations in radiation-sensitive onium salts, making them difficult to use as components in resist compositions.

[0007] The present invention has been made in view of the above problems, and its main objective is to provide a radiation-sensitive composition, an intermediate composition for a radiation-sensitive composition, and a method for forming a resist pattern that have good storage stability, are highly sensitive to radiation, exhibit good CDU performance, and further suppress outgassing.

[0008] The present inventors have found that the above problem can be solved by adding an acid additive having a specific structure together with an iodonium cation to a radiation-sensitive composition containing a resin having an acid-dissociable group. Specifically, the present invention provides the following radiation-sensitive composition, an intermediate composition for a radiation-sensitive composition, and a method for forming a resist pattern.

[0009] The present invention relates to the following [1] to

[15] . [1] A resin containing an acid-dissociable group (A) and an acid additive (C), wherein the resin containing an acid-dissociable group (A) satisfies one or more of the following requirements 1A and 1B: Requirement 1A: The resin containing an acid-dissociable group (A) further contains structural units derived from a radiation-sensitive onium salt (B), Requirement 1B: It further contains a nonpolymer radiation-sensitive onium salt (B), The radiation-sensitive onium salt (B) has an iodonium cation represented by the following formula (B1),

[0010] (In formula (B1), R １ and R ２ Each of these independently represents a substituted or unsubstituted heteroaromatic group or a substituted or unsubstituted aromatic hydrocarbon group, R １ and R ２when is an aromatic hydrocarbon group, at least one of them has an electron-withdrawing group.) The acid additive (C) satisfies at least one of the following requirement c1 and requirement c2, has a pKa of 2.8 or less, and has a boiling point or decomposition temperature of 160°C or higher. Requirement c1: having two or more groups selected from the group consisting of -COOH, -OH, and -NHR (R is a hydrogen atom, a hydrocarbon group, or -C(=O)-R ｃ１ (R ｃ１ represents a hydrogen atom or a hydrocarbon group)). Requirement c2: A radiation-sensitive composition having a phosphonic acid group.

[0011] [2] The radiation-sensitive composition according to [1], wherein the iodonium cation represented by formula (B1) is the iodonium cation represented by the following formula (B2).

[0012] (In formula (B2), Ar １ represents a group obtained by removing (b1+1) hydrogen atoms from a benzene ring or a group obtained by removing (b1+1) hydrogen atoms from a naphthalene ring, and Ar ２ represents a group obtained by removing (b2+1) hydrogen atoms from a benzene ring or a group obtained by removing (b2+1) hydrogen atoms from a naphthalene ring, and X １ and X ２ each independently represent a halogen atom, a haloalkyl group, a cyano group, -C(=O)R ｂ１ (R ｂ１ is -NR ｂ１１ ２ or -OR ｂ１２ , R ｂ１１ represents a hydrogen atom or a hydrocarbon group, R ｂ１２ represents a hydrocarbon group), -SO ２ R ｂ２ (R ｂ２ represents an alkyl group), an alkyl group or an alkoxy group, and at least one of X １ and X ２ is at least one selected from a halogen atom, a haloalkyl group, a cyano group, -C(=O)R ｂ１ (R ｂ１ is -NR ｂ１１ ２ or -OR ｂ１２ , R ｂ１１ represents a hydrogen atom or a hydrocarbon group, R ｂ１２(where represents a hydrocarbon group), or -SO ２ R ｂ２ (R ｂ２ (where b represents an alkyl group, and b1 and b2 each independently represent integers between 0 and 4, provided that at least one of b1 and b2 is between 1 and 4.)

[0013] [3] In formula (B1), R １ and R ２ R is a heteroameric group, １ and R ２ A radiation-sensitive composition according to [1] or [2], wherein each of them independently is a thiophen-2-yl group, a thiophen-3-yl group, a furan-2-yl group, or a furan-3-yl group. [4] A radiation-sensitive composition according to any one of [1] to [3], wherein the acid additive (C) is an aromatic compound represented by the following formula (C1), or squalic acid, oxalic acid, or maleic acid.

[0014] (In formula (C1), R １１ -COOH, -OH, or -NHR (where R is a hydrogen atom, a hydrocarbon group, or -C(=O)-R) ｃ１ (R ｃ１ (represents a hydrogen atom or hydrocarbon group), R １２ (where n represents a halogen atom, haloalkyl group, hydroxyl group, or carboxyl group, n is 0 or 1, and m is an integer between 0 and 4.)

[0015] [5] The radiation-sensitive composition according to any one of [1] to [4], wherein the pKa of the acid additive (C) is -1.9 or higher. [6] The radiation-sensitive composition according to any one of [1] to [5], wherein the acid-dissociable group-containing resin (A) comprises a structural unit having an acid-dissociable group (first structural unit) and a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring (third structural unit) (excluding the first structural unit). [7] The radiation-sensitive composition according to any one of [1] to [6], wherein the content of the acid additive (C) per 100 parts by mass of the radiation-sensitive onium salt (B) is 0.1 parts by mass or more and 500 parts by mass or less. [8] A radiation-sensitive composition according to any one of [1] to [7], wherein the radiation-sensitive onium salt (B) comprises a first onium salt and a second onium salt different from the first onium salt, the first onium salt acting as a radiation-sensitive acid generator and the second onium salt acting as a radiation-decaying quencher. [9] The radiation-sensitive composition according to [8], wherein the first onium salt has an iodonium cation represented by formula (B1) and generates an acid with a higher acidity than the acid generated by the second onium salt.

[10] The radiation-sensitive composition according to [8], wherein the second onium salt has an iodonium cation represented by formula (B1) and generates an acid with a lower acidity than the acid generated by the first onium salt.

[11] A radiation-decaying quencher (F) having an iodonium cation represented by the following formula (B1),

[0016] (In formula (B1), R １ and R ２ Each of these independently represents a heteroaromatic group that may have substituents or an aromatic hydrocarbon group that may have substituents, and R １ and R ２ If is an aromatic hydrocarbon group, at least one of them has an electron-withdrawing group.) An intermediate composition for a radiation-sensitive composition containing an acid additive (D) having a pKa of 3.0 or less and a solvent (E).

[0017]

[12] An intermediate composition for a radiation-sensitive composition according to

[11] , wherein the boiling point or decomposition temperature of the acid additive (D) is 160°C or higher.

[13] An intermediate composition for a radiation-sensitive composition according to

[11] or

[12] , wherein the acid additive (D) satisfies at least one of the following requirements d1 and d2. Requirement d1: -COOH, -OH, and -NHR (where R is a hydrogen atom, a hydrocarbon group, or -C(=O)-R ｄ１ (R ｄ１ A method for forming a resist pattern, comprising the steps of: forming a resist film on a substrate using a radiation-sensitive composition according to any one of [1] to

[10] , having two or more groups selected from the group consisting of (where represents a hydrogen atom or a hydrocarbon group); d2: having a phosphonic acid group; exposing the resist film; and developing the exposed resist film.

[15] The method for forming a resist pattern according to

[14] , wherein the resist film is exposed using extreme ultraviolet light.

[0018] According to the present invention, a radiation-sensitive composition, an intermediate composition for a radiation-sensitive composition, and a method for forming a resist pattern are provided, which have good storage stability, high sensitivity to radiation, good CDU performance, and suppressed outgassing.

[0019] The following details the matters related to the implementation of this disclosure. In this specification, numerical ranges indicated using "~" include the numbers indicated before and after "~" as the lower and upper limits, respectively.

[0020] Herein, in this specification, "hydrocarbon group" means a group of hydrocarbons including linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Linear hydrocarbon group" means a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure and consists only of a linear structure. However, linear hydrocarbon groups may be saturated or unsaturated. "Alicyclic hydrocarbon group" means a hydrocarbon group that contains only the structure of an alicyclic hydrocarbon as its ring structure and does not contain an aromatic ring structure. However, an alicyclic hydrocarbon group does not have to consist only of the structure of an alicyclic hydrocarbon, and may also include a linear structure as part of it. "Aromatic hydrocarbon group" means a hydrocarbon group that contains an aromatic ring structure as its ring structure. However, an aromatic hydrocarbon group does not have to consist only of an aromatic ring structure, and may include a linear structure or an alicyclic hydrocarbon structure as part of it. "Organic group" means an atomic group obtained by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound). "Aromatic ring" is a cyclic structure contained in an aromatic compound. Aromatic rings may consist solely of carbon atoms (e.g., aromatic hydrocarbons and their derivatives), or they may contain elements other than carbon atoms, such as aromatic heterocycles. Aliphatic rings are cyclic structures not included in aromatic compounds. Aliphatic rings may consist solely of carbon atoms (e.g., aliphatic hydrocarbon rings and their derivatives), or they may contain elements other than carbon atoms, such as aliphatic heterocycles. Unless otherwise specified, alkyl groups include linear and cyclic alkyl groups. Linear alkyl groups may be linear or branched. The same applies to alkoxy groups.

[0021] The "main chain" of a polymer refers to the "trunk" portion of the polymer, which consists of the longest chain of atoms. This "trunk" portion may contain a ring structure. For example, "having a specific structure in the main chain" means that the specific structure constitutes a part of the polymer's main chain. A "side chain" refers to a part of the polymer that branches off from the "trunk." A "structural unit" is a unit that mainly constitutes the main chain structure, and is included in the main chain structure in pairs or more. Structural units are typically monomer units. In addition, monomer units having a reactive group are reacted with a compound having a functional group that can react with the reactive group, and monomers protected by protecting groups such as alkali-dissociable groups are polymerized and then deprotected by hydrolysis, and these are also included as "structural units." "(meth)acrylate" is a term that encompasses "acrylate" and "methacrylate."

[0022] The notation "substituted or unsubstituted p-valent hydrocarbon group (where p is an integer of 1 or more)" encompasses both p-valent hydrocarbon groups (i.e., unsubstituted p-valent hydrocarbon groups) and groups obtained by removing p hydrogen atoms from the hydrocarbon structural portion of a substituted hydrocarbon group. Examples of substituted or unsubstituted p-valent hydrocarbon groups include alkyl groups and fluoroalkyl groups, where p=1, and alkanediyl groups and fluoroalkanediyl groups, where p=2. Of these, fluoroalkyl groups correspond to "substituted monovalent hydrocarbon groups," and fluoroalkanediyl groups correspond to "substituted divalent hydrocarbon groups." The same applies to other groups with "substituted or unsubstituted" attached.

[0023] [Radiation-sensitive composition] The radiation-sensitive composition of the present invention (hereinafter also referred to as "this composition") contains an acid-dissociable group-containing resin (A) (hereinafter also referred to as "resin (A)"). This composition also contains a specific radiation-sensitive onium salt (B), which is a component that generates acid upon irradiation with radiation, and a specific acid additive (C) that contributes to the stabilization of the radiation-sensitive onium salt (B).

[0024] <Resin (A)> Resin (A) is not particularly limited as long as it contains structural units having acid-dissociable groups. Here, an acid-dissociable group is a group that substitutes a hydrogen atom on an acid group such as a carboxyl group or a hydroxyl group, and is removed by the action of an acid. By including a polymer having an acid-dissociable group in a radiation-sensitive composition, the acid-dissociable group dissociates due to the acid generated during exposure, producing an acid group, thereby changing the solubility of resin (A) in the developer. It is preferable that such resin (A) constitutes the base resin in this composition.

[0025] For convenience, in the following, among the structural units of resin (A), structural units having an acid-dissociable group will also be referred to as the "first structural unit," and structural units derived from a radiation-sensitive onium salt will also be referred to as the "second structural unit." Furthermore, structural units having an aromatic ring and a hydroxyl group bonded to the aromatic ring will also be referred to as the "third structural unit." Resin (A) has at least the first structural unit, and if the composition satisfies requirement 1A, it has the second structural unit. It is preferable that resin (A) has the third structural unit in addition to the first structural unit, and it is particularly preferable that it has the third structural unit when exposure with short-wavelength radiation such as electron beams or EUV is used.

[0026] (First Structural Unit) The first structural unit is a structural unit of resin (A) that has an acid-dissociable group. The first structural unit is not particularly limited as long as it has an acid-dissociable group. Examples of the first structural unit include the structural unit represented by the following formula (1-1) (hereinafter also referred to as "structural unit (1a)"), the structural unit represented by the following formula (1-2) (hereinafter also referred to as "structural unit (1b)"), and the structural unit represented by the following formula (1-3) (hereinafter also referred to as "structural unit (1c)"). Among these, structural units containing an aromatic ring are preferred. In this specification, structural units having an acid-dissociable group and a hydroxyl group bonded to an aromatic ring are classified as the first structural unit.

[0027] (In formula (1-1), R ３０ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ R is a divalent chain-like organic group or an alicyclic hydrocarbon group.３１ R is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３２ and R ３３ These are, independently of each other, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic heterocyclic group, or R ３２ and R ３３ They are combined with each other R ３２ and R ３３ This represents an alicyclic hydrocarbon structure with 3 to 20 carbon atoms, formed together with the carbon atoms to which it is bonded. However, R ３１ If R is a hydrogen atom, ３２ and R ３３ Either or both of them are independently a substituted or unsubstituted monovalent alicyclic unsaturated hydrocarbon group, a substituted or unsubstituted monovalent aromatic hydrocarbon group, a monovalent aromatic heterocyclic group, or R ３２ and R ３３ They are combined with each other R ３２ and R ３３ This represents an alicyclic unsaturated hydrocarbon structure with 3 to 20 carbon atoms, formed together with the bonded carbon atoms. g1 is 0 or 1. In formula (1-2), R ３０ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ３ These are single bonds, -O-, -CO-, and * ２ -COO- or * ２ -CONH-. "* ２ The symbol " represents a bond to the main chain. ３４ , R ３５ and R ３６ These are, independently of each other, a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted monovalent oxyhydrocarbon group having 1 to 20 carbon atoms. ２８ is a monovalent substituent. g2 is an integer from 0 to 4. In formula (1-3), R ３０ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ４ These are single bonds, -O-, -CO-, and * ３ -COO- or * ３ -CONH-. "* ３ The symbol " represents a bond to the main chain.３７ is a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted monovalent oxyhydrocarbon group having 1 to 20 carbon atoms. R ３８ and R ３９ are each independently a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted monovalent oxyhydrocarbon group having 1 to 20 carbon atoms, or R ３８ and R ３９ are combined with each other to represent an alicyclic hydrocarbon structure having 3 to 20 carbon atoms constituted together with the carbon atom to which R ３８ and R ３９ are bonded. R ２９ is a monovalent substituent. g3 is an integer of 0 to 4.)

[0028] In the above formula (1-1), R ３０ is preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of the copolymerizability of the monomer that gives the structural unit (1a). In the above formula (1-2), R ３０ is preferably a hydrogen atom from the viewpoint of the copolymerizability of the monomer that gives the structural unit (1b). Similarly, R in the above formula (1-3) ３０ is preferably a hydrogen atom or a methyl group.

[0029] In the above formulas (1-1) to (1-3), the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ３１ to R ３３ , R ３４ to R ３６ or R ３７ to R ３９ includes a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0030] The monovalent chain hydrocarbon group having 1 to 20 carbon atoms may be saturated or unsaturated, and may be linear or branched. Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group and t-butyl group; alkenyl groups such as ethenyl group, propenyl group and butenyl group; and alkynyl groups such as ethynyl group, propynyl group and butynyl group. Among these, R１ The monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by is preferably an alkyl group, more preferably an alkyl group having 1 to 10 carbon atoms, and even more preferably an alkyl group having 1 to 5 carbon atoms.

[0031] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monovalent monocyclic alicyclic saturated hydrocarbon groups such as cyclopentyl group, cyclohexyl group, methylcyclopentyl group, ethylcyclopentyl group, methylcyclohexyl group, and ethylcyclohexyl group; monovalent monocyclic alicyclic unsaturated hydrocarbon groups such as cyclopentenyl group, cyclohexenyl group, methylcyclopentenyl group, and methylcyclohexenyl group; monovalent polycyclic alicyclic saturated hydrocarbon groups such as norbornyl group, adamantyl group, and tricyclodecyl group; monovalent polycyclic alicyclic unsaturated hydrocarbon groups such as norbornenyl group, tricyclodecenyl group, and indanyl group. When the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms has a polycyclic structure, the polycyclic structure may be any of a condensed ring structure, a bridged structure, and a spiro ring structure, or may be a combination of two or more of these. In addition to the alicyclic structures shown above, the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms may further have a chain structure (for example, a methyl group, an ethyl group, etc.).

[0032] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl group, tolyl group, xylyl group, mesityl group, naphthyl group, methylnaphthyl group, anthryl group, methylanthryl group, and indenyl group; aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group, and anthrylmethyl group. In addition to the aromatic ring structures shown above, the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms may further have a chain structure or an alicyclic structure (for example, a cycloalkyl group, an alkylcycloalkyl group, etc.). Examples of the monovalent aromatic heterocyclic group include furyl group and thienyl group.

[0033] R ３４ to R ３６ or R ３７ to R ３９Examples of monovalent oxy hydrocarbon groups having 1 to 20 carbon atoms, as represented by , include groups containing an oxygen atom at the end of the bond side of the monovalent chain hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, or monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, as exemplified above. ３２ and R ３３ They are combined with each other R ３２ and R ３３ A cycloaliphatic hydrocarbon structure having 3 to 20 carbon atoms, or R ３８ and R ３９ They are combined with each other R ３８ and R ３９ Specific examples of alicyclic hydrocarbon structures having 3 to 20 carbon atoms that are formed together with the carbon atoms to which they are bonded include ring structures similar to those of the monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms mentioned above.

[0034] R ３１ ~R ３３ , R ３４ ~R ３６ or R ３７ ~R ３９ When the group represented by has substituents, examples of such substituents include halogen atoms, hydroxyl groups, and alkoxy groups having 1 to 3 carbon atoms.

[0035] In the above formula (1-1), L ２ The divalent chain-like organic group represented by is a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, or a chain-like or branched saturated hydrocarbon group in which the methylene group contains a heteroatom (for example, -O-, -S-, -CO-, -COO-, -NH-, -NHCO-, -SO-). ２ Examples include divalent groups with 2 to 20 carbon atoms that are replaced by -). ２ Specific and preferred examples of the divalent alicyclic hydrocarbon group represented by the above formula (1-1) include R ３１ ~R ３３ Examples of monovalent alicyclic hydrocarbon groups represented by include groups obtained by removing one more hydrogen atom. ２ L in formula (1-2) above is preferably a chain-like organic group. ３ or L in formula (1-3) ４A single bond, -COO-, or -CONH- is preferred.

[0036] In the above equation (1-2), R ２８ , R in the above formula (1-3) ２９ Specific examples of substituents represented by include halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.), substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted cycloalkyloxy groups, substituted or unsubstituted aryloxy groups, substituted or unsubstituted aralkyloxy groups, carboxyl groups, ester groups (-COOR, where R is a monovalent hydrocarbon group having 1 to 20 carbon atoms), amide groups (-NH-CO-R' or -CO-NH-R', where R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms), alkylsulfonyl groups, cycloalkylsulfonyl groups, hydroxyl groups, cyano groups, nitro groups, etc. When one or more hydrogen atoms of an alkyl group, alkoxy group, cycloalkyl group, cycloalkyloxy group, aryloxy group, or aralkyloxy group are substituted, examples of substituents include halogen atoms, hydroxyl groups, cyano groups, nitro groups, etc. g2 and g3 are each preferably 0 to 2.

[0037] Specific examples of structural unit (1a) among the first structural units include the structural unit represented by the following formula.

[0038]

[0039]

[0040] Specific examples of structural units (1b) include structural units represented by the following formula.

[0041]

[0042] Specific examples of structural units (1c) include structural units represented by the following formula.

[0043]

[0044]

[0045] In the formula, R ３０This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. However, the first structural unit is not limited to the specific examples above.

[0046] In resin (A), the content of the first structural unit is preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more, relative to the total amount of structural units in resin (A). Furthermore, the content of the first structural unit is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less, relative to the total amount of structural units in resin (A). By setting the content of the first structural unit within the above range, the difference in dissolution rate between the exposed and unexposed areas in the developer can be appropriately increased while maintaining good sensitivity of the composition, thereby improving the CDU performance of the composition.

[0047] (Second Structural Unit) The second structural unit is a structural unit derived from a radioactive onium salt. When the organic anion in the second structural unit is a sulfonate anion, the second structural unit can function mainly as a radioactive acid generator by generating a strong acid that induces the dissociation of an acid-dissociating group under normal conditions. On the other hand, when the organic anion in the second structural unit is a carboxylic acid anion, the second structural unit can function mainly as a radioactive decay quencher that controls the diffusion of the acid generated by the radioactive acid generator by generating a weak acid that does not induce the dissociation of an acid-dissociating group under normal conditions. "Normal conditions" here refers to the conditions under which a post-exposure bake (PEB) is performed at 110°C for 60 seconds.

[0048] The second structural unit is typically a monomer having a radiation-sensitive onium cation and an organic anion, and having a polymerization-involved group in the radiation-sensitive onium cation or organic anion. The second structural unit is an organic anion structure (-SO ３ － Ya-COO －The second structural unit may be bonded to the main chain of the polymer via a linking group, and the radiation-sensitive onium cation may form a counterion. Alternatively, the radiation-sensitive onium cation structure may be bonded to the main chain of the polymer via a linking group, and the organic anion may form a counterion. In order to improve the CDU performance of this composition, it is preferable that the second structural unit has an organic anion structure bonded to the main chain of the polymer via a linking group, and the sulfonic acid anion structure (-SO ３ － It is more preferable that the ) is bonded to the main chain of the polymer via a linking group.

[0049] From the viewpoint of increasing the sensitivity of the composition, the radiation-sensitive cation in the second structural unit is preferably a sulfonium cation or an iodonium cation, and more preferably a triarylsulfonium cation or a diaryliodonium cation. From the viewpoint of further increasing the sensitivity of the composition, the aromatic ring (i.e., S) of the triarylsulfonium cation or diaryliodonium cation is preferred. ＋ Or I ＋ It is preferable that at least one of the following is bonded to the aromatic ring: an iodine group, a fluoro group, and a fluoroalkyl group. The fluoroalkyl group is preferably a trifluoromethyl group.

[0050] Furthermore, if the composition does not contain a nonpolymeric radiation-sensitive onium salt (B), the resin (A) contains a second structural unit, and the second structural unit contains an iodonium cation represented by formula (B1). In this case, the composition satisfies requirement 1A, and the second structural unit in the resin (A) contains an iodonium cation represented by formula (B1).

[0051] Specific examples of the second structural unit include the structural unit represented by the following formula. However, the second structural unit is not limited to these specific examples. Specific examples of the iodonium cation represented by formula (B1) will be discussed later.

[0052] (In the formula, R ４０ This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＋This is a sulfonium cation or an iodonium cation. － (This is a sulfonate anion.)

[0053] When resin (A) contains a second structural unit, the content of the second structural unit in resin (A) is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more, relative to the total amount of structural units in resin (A). Furthermore, the content of the second structural unit in resin (A) is preferably 25 mol% or less, and more preferably 20 mol% or less, relative to the total amount of structural units in resin (A). By setting the content of the second structural unit within the above range, the sensitivity and CDU performance of this composition can be appropriately enhanced.

[0054] (Third Structural Unit) Resin (A) may further contain a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring (referred to as the "third structural unit"). The presence of a hydroxyl group bonded to the aromatic ring in resin (A) is preferable in that it can further improve the CDU performance of the composition, and has a high effect in suppressing the dissolution of unexposed areas into the developer, thereby sufficiently reducing development defects. Furthermore, resin (A) containing the third structural unit can be preferably used in pattern formation using exposure with radiation of wavelength 50 nm or less, such as electron beams and EUV. Note that the third structural unit differs from the first structural unit in that it does not have an acid-dissociable group, and differs from the second structural unit in that it does not have an onium salt structure. In other words, the third structural unit is the first structural unit and the second structural unit excluded.

[0055] A preferred example of the third structural unit is the structural unit represented by the following formula (3).

[0056] In formula (3), R ６０ L is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. １ This is a single bond, -COO- or -CONH-. １ R is a group obtained by removing (n1 + n2 + 1) hydrogen atoms from an aromatic ring. ４１ R is a substituent different from a hydroxyl group. n1 is an integer greater than or equal to 1. n2 is an integer greater than or equal to 0. If n2 is 2 or greater, multiple R４１ They are the same or different.

[0057] In the above formula (3), R ６０ From the viewpoint of copolymerization of the monomer that gives the third structural unit, a hydrogen atom or a methyl group is preferred.

[0058] A １ This is a group obtained by removing (n1 + n2 + 1) hydrogen atoms from the ring portion of an aromatic ring. The aromatic ring is preferably an aromatic hydrocarbon ring, such as a benzene ring, naphthalene ring, anthracene ring, or phenanthrene ring. From the viewpoint of ease of synthesis and sensitivity of the monomer that gives the third structural unit, A １ The aromatic ring present is preferably a benzene ring or a naphthalene ring, with a benzene ring being more preferable.

[0059] The position of the hydroxyl group bonded to the aromatic ring is not particularly limited. For example, if the third structural unit has a hydroxyl group bonded to a benzene ring, the bonded position of the hydroxyl group on the benzene ring in the third structural unit may be ortho, meta, or para relative to the other groups.

[0060] R ４１ The group can be any group different from a hydroxyl group. ４１ A specific example is R in equation (1-2) above. ２８ , R in the above formula (1-3) ２９ Examples of substituents represented by include groups other than hydroxyl groups among the exemplified groups. n1 is preferably 1 to 3, and preferably 1 or 2. n2 is preferably 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0061] Specific examples of the third structural unit include the structural unit represented by the following formula. However, the third structural unit is not limited to these specific examples.

[0062]

[0063] (In the formula, R ６０ (This is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group.)

[0064] In resin (A), the content of the third structural unit is preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more, relative to the total amount of structural units in resin (A). Furthermore, the content of the third structural unit is preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 60 mol% or less, relative to the total amount of structural units in resin (A). By setting the content of the third structural unit within the above range, the CDU performance of this composition can be made even better.

[0065] (Fourth structural unit) In addition to the first to third structural units described above, resin (A) may have a fourth structural unit which is a lactone structure, a cyclic carbonate structure, a sultone structure, or a ring structure which is a combination of two or more of these (excluding the first to third structural units).

[0066] Specific examples of the fourth structural unit include the structural unit represented by the following formula. However, the fourth structural unit is not limited to these specific examples.

[0067]

[0068]

[0069] (In the formula, R Ｌ１ (This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.)

[0070] If resin (A) contains a fourth structural unit, the content of the fourth structural unit is preferably 1 mol% or more, and more preferably 2 mol% or more, relative to the total amount of structural units in resin (A). Furthermore, the content of the fifth structural unit in resin (A) is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less, relative to the total amount of structural units in resin (A).

[0071] (Fifth Structural Unit) In addition to the first to fourth structural units described above, resin (A) may further include a fifth structural unit having an alcoholic hydroxyl group (excluding the first to fourth structural units). By introducing the fifth structural unit into resin (A), the effect of suppressing development defects when a resist pattern is formed with this composition can be enhanced. Herein, in this specification, "alcoholic hydroxyl group" refers to a group having a structure in which a hydroxyl group is directly bonded to an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a chain hydrocarbon group or an alicyclic hydrocarbon group.

[0072] The fifth structural unit is preferably derived from an unsaturated monomer having an alcoholic hydroxyl group. The structure of the unsaturated monomer that gives the fifth structural unit is not particularly limited. Specific examples of the fifth structural unit include the structural unit represented by the following formula. However, the fifth structural unit is not limited to these specific examples.

[0073] (In the formula, R Ａ (This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.)

[0074] When resin (A) contains a fifth structural unit, from the viewpoint of enhancing the effect of suppressing development defects in the resist pattern, the content of the fifth structural unit is preferably 1 mol% or more, and more preferably 3 mol% or more, relative to the total amount of structural units in resin (A). Furthermore, the content of the fifth structural unit is preferably 30 mol% or less, and more preferably 20 mol% or less, relative to the total amount of structural units in resin (A).

[0075] Other structural units of resin (A) include, in addition to the second to fifth structural units, structural units containing cyano groups, nitro groups, or sulfonamide groups (specifically, structural units derived from 2-cyanomethyladamantan-2-yl(meth)acrylate); and structural units containing non-acid-dissociable hydrocarbon groups (specifically, structural units derived from styrene or halogenated styrene (e.g., styrene units, bromostyrene units, etc.), structural units derived from vinylnaphthalene, structural units derived from n-pentyl(meth)acrylate, etc.). The content ratio of these structural units can be appropriately set according to each structural unit, as long as it does not impair the effects of the present invention.

[0076] The weight-average molecular weight (Mw) of resin (A) in terms of polystyrene, determined by gel permeation chromatography (GPC), is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and particularly preferably 4,000 or more. Furthermore, the Mw of resin (A) is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, and particularly preferably 15,000 or less. Setting the Mw of resin (A) within the above range is advantageous in that it improves the coating properties of the composition and sufficiently suppresses development defects.

[0077] The ratio of Mw to the number-average molecular weight (Mn) of resin (A) in polystyrene equivalent, calculated by GPC (Mw / Mn, hereinafter also referred to as "dispersion"), is preferably 5.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less. In addition, the Mw / Mn of resin (A) is usually 1.0 or more.

[0078] Resin (A) is preferably incorporated into the composition as a base resin. In this composition, the content of resin (A) is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, based on the total amount of solids contained in the composition. If resin (A) is composed of two or more types, the total amount of those two or more resins should be within the above range.

[0079] Resin (A) can be synthesized, for example, by polymerizing monomers that give each structural unit in a suitable solvent using a known radical polymerization initiator. Examples of radical polymerization initiators include azo radical initiators (e.g., azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), etc.) and peroxide radical initiators (e.g., benzoyl peroxide, etc.). Examples of solvents used for polymerization include linear alkanes, cycloalkanes, aromatic hydrocarbons, halogenated hydrocarbons, saturated carboxylic acid esters, ketones, ethers, and alcohols. The reaction temperature in polymerization is preferably 40 to 150°C, and more preferably 50 to 120°C. The reaction time is preferably 1 to 48 hours, and more preferably 2 to 24 hours.

[0080] <Radiation-sensitive onium salt (B)> This composition contains a radiation-sensitive onium salt (B) to ensure high sensitivity and excellent CDU performance. The radiation-sensitive onium salt (B) incorporated into this composition may be a so-called radiation-sensitive acid generator or a radioactive decay quencher. Furthermore, this composition may contain both a radiation-sensitive acid generator and a radioactive decay quencher as the onium salt component. Here, the acid generator is a substance that generates a strong acid in this composition that, upon exposure, can detach the acid-dissociable groups of the components in the radiation-sensitive composition from those components. The radioactive decay quencher is a substance that generates a weak acid in this composition that, upon exposure, does not induce the detachment of acid-dissociable groups of the components in the radiation-sensitive composition, thereby suppressing the diffusion of acid derived from the acid generator in the resist film and suppressing chemical reactions caused by acid in non-exposed areas. A preferred embodiment of this composition contains a first onium salt and a second onium salt, where the first onium salt is an acid generator and the second onium salt is a radioactive decay quencher. The first onium salt generates an acid with a higher acidity than the acid generated by the second onium salt.

[0081] This composition contains at least one radiation-sensitive onium salt (B) selected from the group consisting of structural units derived from radiation-sensitive onium salts and non-polymerized radiation-sensitive onium salts. That is, this composition satisfies one or more of the following requirements 1A and 1B. Requirement 1A: The resin (A) further contains structural units derived from radiation-sensitive onium salt (B). Requirement 1B: It further contains non-polymerized radiation-sensitive onium salt (B). The non-polymerized radiation-sensitive onium salt (B) is a component (specifically, an additive component) that is compounded separately from the resin (A).

[0082] The radiation-sensitive onium salt (B) that provides the second structural unit and the non-polymerized radiation-sensitive onium salt (B) are substances that generate acid upon irradiation with radiation, and typically consist of a radiation-sensitive onium cation and an organic anion that is the conjugate base of the acid. It is thought that these radiation-sensitive onium salts (B) release the organic anion when the radiation-sensitive onium cation decomposes under the action of radiation, and that the released organic anion then combines with hydrogen extracted from components contained in this composition (e.g., other radiation-sensitive onium salts or solvents) to produce an acid derived from the organic anion. Here, in this specification, "radiation" is a term that includes electron beams (visible light, ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays (EUV), etc.) and electromagnetic waves (X-rays, gamma rays, etc.). An organic anion is usually an anion obtained by removing a proton from the acid group of an organic acid. Examples of organic anions include sulfonic acid anions and carboxylic acid anions.

[0083] The radioactive onium salt is classified as an acid generator or a radioactive decay quencher depending on the relative acidity of the radioactive onium salt contained in the composition. The degree of acidity can be evaluated by the acid dissociation constant (pKa). For example, the acid dissociation constant of the acid that generates a radioactive decay quencher is usually -3 or higher, preferably -1 ≤ pKa ≤ 7, and more preferably 0 ≤ pKa ≤ 5. A preferred embodiment of the composition satisfies requirement 1B and contains a nonpolymer radioactive onium salt (B) comprising a first onium salt and a second onium salt that generates an acid with lower acidity than the acid generated by the first onium salt. The molecular weight of the nonpolymer radioactive onium salt (B) is preferably 2,000 or less, more preferably 1,800 or less, and even more preferably 1,500 or less.

[0084] In particular, the radiation-sensitive onium salt (B) contained in this composition contains a specific iodonium cation represented by the following formula (B1) as a radiation-sensitive onium cation. That is, the iodonium cation may be present in the nonpolymerized radiation-sensitive onium salt (B), or in the resin (A). Furthermore, both the nonpolymerized radiation-sensitive onium salt (B) and the resin (A) may have the iodonium cation. Also, the first onium salt may have the iodonium cation represented by the following formula (B1), and the second onium salt may have the iodonium cation represented by the following formula (B1).

[0085] (In formula (B1), R １ and R ２ Each of these independently represents a substituted or unsubstituted heteroaromatic group or a substituted or unsubstituted aromatic hydrocarbon group, R １ and R ２ If it is an aromatic hydrocarbon group, at least one of them has an electron-withdrawing group.

[0086] In the above formula (B1), R １ or R ２When R is a substituted or unsubstituted heteroaromatic group, examples of heteroaromatic rings possessed by the heteroaromatic group include oxygen-containing heterocycles such as furan rings; sulfur-containing heterocycles such as thiophene rings; and nitrogen-containing heterocycles such as pyridine rings and 1H-indole rings. Examples of aromatic rings possessed by aromatic hydrocarbon groups include benzene rings, naphthalene rings, anthracene rings, and phenanthrene rings. Of these, R １ and R ２ The group is preferably a substituted or unsubstituted aromatic hydrocarbon group or a sulfur-containing aromatic group, more preferably a substituted or unsubstituted benzene ring or a naphthalene ring, and even more preferably a substituted or unsubstituted benzene ring. １ or R ２ If R is a substituted or unsubstituted heteroaromatic group, １ and R ２ Preferably, only one of the groups is a heteroaromatic group, and the heteroaromatic group is preferably a thiophene-2-yl group, a thiophene-3-yl group, a furan-2-yl group, a furan-3-yl group, or a 1H-indole-3-yl group, and more preferably a thiophene-2-yl group or a thiophene-3-yl group.

[0087] Substituents on heteroaromatic groups and aromatic hydrocarbon groups include halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.), substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryloxy groups, substituted or unsubstituted aralkyloxy groups, carboxyl groups, and -C(=O)R groups. ｂ１ (R ｂ１ -NR ｂ１１ ２ OR ｂ１２ And R ｂ１１ R represents a hydrogen atom or a hydrocarbon group. ｂ１２ (represents a hydrocarbon group), amide group (-NH-CO-R'), -SO ２ R ｂ２ (R ｂ２Examples of substituents include alkyl groups, hydroxyl groups, cyano groups, nitro groups, etc. When one or more hydrogen atoms of an alkyl group, alkoxy group, cycloalkyl group, cycloalkyloxy group, aryloxy group, or aralkyloxy group are substituted, examples of substituents include halogen atoms, hydroxyl groups, cyano groups, nitro groups, etc.

[0088] In equation (B1), R １ and R ２ If is an aromatic hydrocarbon group, then at least R １ and R ２ One of them has an electron-withdrawing group. That is, R １ and R ２ If the group is an aromatic hydrocarbon group, at least one of the aromatic rings has an electron-withdrawing group as a substituent. Examples of electron-withdrawing groups that can substitute for an aromatic hydrocarbon group include halogen atoms, haloalkyl groups, cyano groups, and -C(=O)R ｂ１ (R ｂ１ -NR ｂ１１ ２ OR ｂ１２ And R ｂ１１ Each of these independently represents a hydrogen atom or a hydrocarbon group, R ｂ１２ (represents a hydrocarbon group), -SO ２ R ｂ２ (R ｂ２ Examples include R (where R represents an alkyl group). ｂ１１ When is a hydrocarbon group, the number of carbon atoms is preferably 1 to 16, more preferably 1 to 8, and even more preferably 1 to 4, and alkyl groups are preferably exemplified as hydrocarbon groups. Also, R ｂ１２ The number of carbon atoms is preferably 1 to 16, more preferably 1 to 8, and even more preferably 1 to 4, and alkyl groups are preferably exemplified as hydrocarbon groups.

[0089] The iodonium cation represented by the above formula (B1) is preferably the iodonium cation represented by the following formula (B2).

[0090] (In formula (B2), Ar １Ar represents a group obtained by removing (b1+1) hydrogen atoms from a benzene ring or a group obtained by removing (b1+1) hydrogen atoms from a naphthalene ring. ２ represents a group obtained by removing (b² + 1) hydrogen atoms from a benzene ring or a group obtained by removing (b² + 1) hydrogen atoms from a naphthalene ring, X １ and X ２ Each of these is independently a halogen atom, a haloalkyl group, a cyano group, and -C(=O)R ｂ１ (R ｂ１ -NR ｂ１１ ２ OR ｂ１２ And R ｂ１１ R represents a hydrogen atom or a hydrocarbon group. ｂ１２ (represents a hydrocarbon group), -SO ２ R ｂ２ (R ｂ２ X represents an alkyl group, an alkyl group or an alkoxy group, １ and X ２ At least one of them is a halogen atom, a haloalkyl group, a cyano group, or -C(=O)R ｂ１ (R ｂ１ -NR ｂ１１ ２ OR ｂ１２ And R ｂ１１ R represents a hydrogen atom or a hydrocarbon group. ｂ１２ (where represents a hydrocarbon group), or -SO ２ R ｂ２ (R ｂ２ (where b represents an alkyl group, and b1 and b2 each independently represent integers between 0 and 4, provided that at least one of b1 and b2 is between 1 and 4.)

[0091] Ar １ Ar is a group obtained by removing (b1+1) hydrogen atoms from a benzene ring or a naphthalene ring, and it is preferable that it is a group obtained by removing (b1+1) hydrogen atoms from a benzene ring. ２ This group is obtained by removing (b² + 1) hydrogen atoms from a benzene ring or a naphthalene ring, and it is preferable that it is obtained by removing (b² + 1) hydrogen atoms from a benzene ring.

[0092] X １ and X ２Each of these is independently a halogen atom, a haloalkyl group, a cyano group, and -C(=O)R ｂ１ (R ｂ１ -NR ｂ１１ ２ OR ｂ１２ And R ｂ１１ R represents a hydrogen atom or a hydrocarbon group. ｂ１２ (represents a hydrocarbon group), -SO ２ R ｂ２ (R ｂ２ ∫(=O)R represents an alkyl group, or an alkyl or alkoxy group. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms. The number of carbon atoms in the haloalkyl group is preferably 1 to 6, more preferably 1 to 3, and even more preferably 1. It is sufficient that at least one of the hydrogen atoms of the alkyl group is substituted with a halogen atom, but it is preferable that all of the hydrogen atoms of the alkyl group are substituted with halogen atoms. -C(=O)R ｂ１ (R ｂ１ -NR ｂ１１ ２ OR ｂ１２ And R ｂ１１ R represents a hydrogen atom or a hydrocarbon group. ｂ１２ If R represents a hydrocarbon group, ｂ１１ Each of these independently represents a hydrogen atom or a hydrocarbon group, and the two R ｂ１１ Preferably, at least one of the hydrocarbon groups is a hydrocarbon group, and more preferably, two are hydrocarbon groups. The number of carbon atoms in the hydrocarbon group is preferably 1 to 20, more preferably 1 to 6, even more preferably 1 to 3, and particularly preferably 1, and it is preferably a chain-like alkyl group. -SO ２ R ｂ２ (R ｂ２ If R represents an alkyl group, ｂ２The alkyl group is a linear alkyl group or a cycloalkyl group, and is preferably a linear alkyl group. The number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 12, even more preferably 1 to 4, and particularly preferably a methyl group. If it is an alkyl group, the alkyl group is a linear alkyl group or a cycloalkyl group. The number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 12, even more preferably 1 to 6, and particularly preferably 1 to 4. If it is an alkoxy group, the alkyl group of the alkoxy group is a linear alkyl group or a cycloalkyl group. The number of carbon atoms in the alkoxy group is preferably 1 to 20, more preferably 1 to 12, even more preferably 1 to 6, and particularly preferably 1 to 4. Among these, X １ and X ２ Each of these is preferably an independent halogen atom or a haloalkyl group.

[0093] b1 and b2 are between 0 and 4, and at least one of b1 and b2 is between 1 and 4. Preferably, b1 and b2 are between 0 and 3, more preferably between 0 and 2.

[0094] A specific example of the iodonium cation represented by formula (B1) is the cation represented by the following formula.

[0095]

[0096] Specific embodiments of the composition containing an iodonium cation include the following embodiments [1C] to [3C] and embodiments combining two or more of these. Embodiment [1C]: Satisfies requirement 1B and includes a first onium salt and a second onium salt as the radiation-sensitive onium salt (B), wherein the first onium salt has an iodonium cation represented by formula (B1). Embodiment [2C]: Satisfies requirement 1B and includes a first onium salt and a second onium salt as the radiation-sensitive onium salt (B), wherein the second onium salt has an iodonium cation represented by formula (B1). Embodiment [3C]: Satisfies requirement 1A and the second structural unit in the resin (A) contains an iodonium cation represented by formula (B1). In terms of ease of adjusting the sensitivity and lithography characteristics of the composition, it is preferable that the composition satisfies requirement 1B, and it is more preferable that at least a portion of the nonpolymer radiation-sensitive onium salt (B) contained in the composition has an iodonium cation represented by formula (B1).

[0097] The radiation-sensitive onium salt (B) contained in this composition preferably includes an onium salt comprising an iodonium cation represented by formula (B1) and an organic anion, in that it can improve the sensitivity of this composition. Furthermore, if this composition contains a first onium salt and a second onium salt, at least one of the first onium salt and the second onium salt contains an iodonium cation represented by formula (B1) above. In this case, the first onium salt may have an iodonium cation represented by formula (B1) above, and the second onium salt may have an iodonium cation represented by formula (B1) above. Furthermore, both the first onium salt and the second onium salt may have an iodonium cation represented by formula (B1) above.

[0098] Examples of radiation-sensitive cations constituting the first and second onium salts include iodonium cations and sulfonium cations. Specific examples of iodonium cations are as described above. From the viewpoint of sensitivity, arylsulfonium cations are preferred, and triarylsulfonium cations are more preferred. Specific examples of sulfonium cations include, for example, cations represented by the following formula.

[0099]

[0100] Examples of organic anions constituting the first onium salt include sulfonic acid anions, carboxylic acid anions, imido acid anions, and methido acid anions. Of these, sulfonic acid anions are preferred because they allow for high sensitivity of the composition. Specific examples of sulfonic acid anions include, for example, the anions represented by the following formula.

[0101]

[0102]

[0103]

[0104] The organic anion constituting the second onium salt is preferably a carboxylic acid anion. Specific examples of carboxylic acid anions include the anion represented by the following formula.

[0105]

[0106] When a first onium salt (acid generator) is incorporated into this composition, the content of the first onium salt is preferably 1 part by mass or more, and more preferably 5 parts by mass or more, per 100 parts by mass of resin (A), from the viewpoint of improving the sensitivity of this composition. Furthermore, from the viewpoint of suppressing the occurrence of development defects caused by an excess amount of the first onium salt, the content of the first onium salt is preferably 60 parts by mass or less, and more preferably 40 parts by mass or less, per 100 parts by mass of resin (A).

[0107] Furthermore, when a second onium salt (radiation-decaying quencher) is incorporated into this composition, the content of the second onium salt is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, relative to the total amount of the first onium salt contained in this composition and the monomer that provides the second structural unit in resin (A) and corresponds to the first onium salt. Furthermore, the content of the second onium salt is preferably 100 mol% or less, more preferably 80 mol% or less, even more preferably 50 mol% or less, and particularly preferably 30 mol% or less, relative to the total amount of the first onium salt contained in this composition and the monomer that provides the second structural unit in resin (A) and corresponds to the first onium salt.

[0108] <Acid Additive (C)> This composition contains an acid additive (C) that satisfies at least one of the following requirements c1 or c2, has a pKa of 2.8 or less, and has a boiling point or decomposition temperature of 160°C or higher. Requirement c1: -COOH, -OH, and -NHR (where R is a hydrogen atom, a hydrocarbon group, or -C(=O)-R ｃ１ (R ｃ１ Requirement c2: The stability of the iodonium cation represented by formula (B1) is improved by adding the above acid additive (C) having a phosphonic acid group, which has two or more groups selected from the group consisting of (where represents a hydrogen atom or a hydrocarbon group). Among these, it is preferable that requirement c1 is satisfied.

[0109] Here, compared to sulfonium cations, which are commonly used as cations in radiation-sensitive onium salts, iodonium cations, particularly the iodonium cation represented by formula (B1), have higher radiation (especially EUV) absorption efficiency. Therefore, in order to meet the demand for further miniaturization of resist patterns in recent years, it is desirable to develop a technology that utilizes iodonium cations instead of sulfonium cations to obtain resist compositions that are more sensitive and have superior lithography performance than conventional compositions. On the other hand, iodonium cations have poor storage stability and are difficult to use. The present invention has made it possible to improve sensitivity and CDU performance while ensuring the storage stability of the composition by introducing an acid additive (C) having a specific structure together with the iodonium cation into the radiation-sensitive composition. The requirements for the acid additive (C) will be explained below.

[0110] The pKa (acid dissociation constant) of the acid additive (C) is 2.8 or less, preferably between -1.9 and 2.8, from the viewpoint of improving storage stability. The pKa is preferably 2.7 or less, more preferably between -1.0 and above, even more preferably between 0 and above, and particularly preferably between 1.0 and above. The pKa of the acid additive (C) is preferably greater than the pKa of the acid generated from the acid generator (first onium salt). For known pKa values, the known value is adopted. If the pKa is unknown, the acid dissociation constant pKa was determined using ChemDraw (PerkinElmer). If there are two or more pKa values, the lowest pKa value is adopted.

[0111] The boiling point or decomposition temperature of the acid additive (C) is 160°C or higher, from the viewpoint of suppressing outgassing. That is, if the acid additive (C) has a boiling point, that boiling point is 160°C or higher, and if the acid additive (C) does not have a boiling point but has a decomposition temperature, that decomposition temperature is 160°C or higher. The boiling point or decomposition temperature of the acid additive (C) is preferably 180°C or higher, more preferably 200°C or higher. There is no particular upper limit to the boiling point or decomposition temperature of the acid additive (C). If the acid additive (C) has a boiling point, the known value shall be adopted if the boiling point of the acid additive (C) is known. If the boiling point is unknown, it shall be measured in accordance with JIS K 0066:1992 "Test Method for Distillation of Chemical Products". If the acid additive (C) does not have a boiling point but has a decomposition temperature, the known value shall be adopted if the decomposition temperature of the acid additive (C) is known. Furthermore, if the decomposition temperature is unknown, it will be measured by thermogravimetric analysis.

[0112] (Requirement c1) The acid additive (C) is -COOH, -OH, and -NHR (where R is a hydrogen atom, a hydrocarbon group, or -C(=O)-R ｃ１ (R ｃ１ R has two or more groups selected from the group consisting of (where R represents a hydrogen atom or a hydrocarbon group). When R is a hydrocarbon group, the number of carbon atoms in the hydrocarbon group is preferably 1 to 12, more preferably 1 to 6, even more preferably 1 to 3, and particularly preferably 1. ｃ１ If is a hydrocarbon group, the number of carbon atoms in the hydrocarbon group is preferably 1 to 12, more preferably 1 to 6, even more preferably 1 to 3, and particularly preferably 1. R is a hydrogen atom or -C(=O)-R ｃ１ Preferably, it is a hydrogen atom or -C(=O)-CH ３ It is more preferable that the following are present. Among these, it is preferable that the present member has at least one carboxyl group (-COOH), and it is more preferable that the present member has at least one -OH, -NHR, or -COOH group in addition to the carboxyl group.

[0113] If requirement c1 is met, the acid additive (C) is preferably an aromatic compound represented by the following formula (C1), or squalic acid, oxalic acid, or maleic acid.

[0114] (In formula (C1), R １１ -COOH, -OH, or -NHR (where R is a hydrogen atom, a hydrocarbon group, or -C(=O)-R) ｃ１ (R ｃ１ R represents a hydrogen atom or hydrocarbon group. １２ (where n represents a halogen atom, haloalkyl group, hydroxyl group, or carboxyl group, n is 0 or 1, and m is an integer between 0 and 4.)

[0115] In formula (C1), R １１ -COOH, -OH, or -NHR (where R is a hydrogen atom, a hydrocarbon group, or -C(=O)-R) ｃ１ (R ｃ１ (where represents a hydrogen atom or hydrocarbon group), -COOH, -OH, or -NH-C(=O)CH ３ It is preferable that this is the case. １２ The compound has a halogen atom, a haloalkyl group, a hydroxyl group, or a carboxyl group, and examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms. The number of carbon atoms in the haloalkyl group is preferably 1 to 6, more preferably 1 to 3, and even more preferably 1. An example of a haloalkyl group is a trifluoromethyl group. In formula (C1), n ​​is 0 or 1, and when n is 0, the compound represented by formula (C1) has a carboxyl group and R at the ortho position of the benzene ring. １１ It has 0 to 4 R １２ It has as a substituent on the benzene ring. Also, when n is 1, the compound represented by formula (C1) has a carboxyl group at the 2 position of the naphthalene ring and R at the 3 position. １１ It has 0 to 4 R １２ It has as a substituent on the naphthalene ring.

[0116] (Requirement c2) The acid additive (C) has a phosphonic acid group. Examples of acid additives (C) having a phosphonic acid group include benzenephosphonic acid, methylphosphonic acid, vinylphosphonic acid, and (carboxymethyl)phosphonic acid, and among these, benzenephosphonic acid is preferred.

[0117] Specific examples of acid additives (C) include the following compounds.

[0118]

[0119] In this composition, the content of the acid additive (C) is preferably 0.1 parts by mass or more and 500 parts by mass or less, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, and even more preferably 200 parts by mass or less, and even more preferably 120 parts by mass or less, per 100 parts by mass of the radiation-sensitive onium salt (B). The mass of the radiation-sensitive onium salt (B) is the sum of the mass of structural units derived from the radiation-sensitive onium salt (B) in the acid-dissociable group-containing resin (A) (the mass of the acid-dissociable group-containing resin (A) derived from the above structural units) and the mass of the nonpolymerized radiation-sensitive onium salt (B).

[0120] <High Fluorine Content Polymer> This composition may contain a high fluorine content polymer with a higher mass content of fluorine atoms than resin (A). As the high fluorine content polymer, the high fluorine content polymer described in International Publication No. 2025 / 004621 can be suitably used. Furthermore, the high fluorine content polymer incorporated into this composition may contain the second structural unit of resin (A), and the second structural unit may contain an iodonium cation represented by formula (B1).

[0121] If the composition contains a high-fluorine content polymer, the content of the high-fluorine content polymer in the composition is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of resin (A). Furthermore, the content of the high-fluorine content polymer is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of resin (A).

[0122] <Other Components> This composition may further contain components other than the resin (A), radiation-sensitive onium salt (B), acid additive (C), and high-fluorine polymer described above (hereinafter also referred to as "other components"). Examples of other components are listed below.

[0123] (Solvent (E)) The solvent is preferably a solvent capable of dissolving or dispersing the components incorporated into this composition, and organic solvents can be preferably used. Specific examples of solvents include alcohols, ethers, ketones, amides, esters, hydrocarbons, and the like.

[0124] Examples of alcohols include aliphatic monoalcohols with 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol; alicyclic monoalcohols with 3 to 18 carbon atoms such as cyclohexanol; polyhydric alcohols with 2 to 18 carbon atoms such as 1,2-propylene glycol; and polyhydric alcohol partial ethers with 3 to 19 carbon atoms such as propylene glycol monomethyl ether. Examples of ethers include dialkyl ethers such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether; cyclic ethers such as tetrahydrofuran and tetrahydropyran; and aromatic ring-containing ethers such as diphenyl ether and anisole.

[0125] Examples of ketones include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-iso-butyl ketone, trimethylnonanone, and other linear ketones; cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, and other cyclic ketones; and 2,4-pentanedione, acetonylacetone, acetophenone, and diacetone alcohol. Examples of amides include cyclic amides such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and linear amides such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0126] Examples of esters include monocarboxylic acid esters such as n-butyl acetate, ethyl lactate, and methyl 2-hydroxyisobutyrate; polyhydric alcohol carboxylates such as propylene glycol diacetate; polyhydric alcohol partial ether carboxylates such as propylene glycol monomethyl ether acetate; polyhydric carboxylic acid diesters such as diethyl oxalate; carbonates such as dimethyl carbonate and diethyl carbonate; and cyclic esters such as γ-butyrolactone. Examples of hydrocarbons include aliphatic hydrocarbons with 5 to 12 carbon atoms such as n-pentane and n-hexane; and aromatic hydrocarbons with 6 to 16 carbon atoms such as toluene and xylene.

[0127] The solvent preferably contains at least one selected from the group consisting of esters and ketones, and more preferably contains monocarboxylic acid esters and polyhydric alcohol partial ether carboxylates.

[0128] (Other Optional Components) This composition may further contain components other than solvents (hereinafter also referred to as "other optional components"). Examples of other optional components include surfactants, alicyclic skeleton-containing compounds (e.g., 1-adamantanatecarboxylic acid, 2-adamantanone, t-butyl deoxycholate, etc.), sensitizers, and segregation promoters.

[0129] <Method for Producing Radiation-Sensitive Composition> This composition can be produced by mixing resin (A) with components such as solvents as needed in desired proportions, and filtering the resulting mixture, preferably using a filter (for example, a filter with a pore size of about 0.2 μm). The solid content concentration of this composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. Furthermore, the solid content concentration of this composition is preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 5% by mass or less. Setting the solid content concentration of this composition within the above range is advantageous in that it allows for good coatability and good shape of the resist pattern.

[0130] The resulting composition can be used as a positive-type pattern-forming composition for forming patterns using an alkaline developer, or as a negative-type pattern-forming composition for using a developer containing an organic solvent.

[0131] [Method for Forming a Resist Pattern] The resist pattern formation method in this disclosure preferably comprises the following steps 1 to 3. Step 1: A step of forming a resist film on a substrate using the composition (film formation step) Step 2: A step of exposing the resist film (exposure step) Step 3: A step of developing the exposed resist film (development step) The film formation step is preferably a step of coating the composition onto one side of the substrate. Examples of patterns formed by the resist pattern formation method of this disclosure include line and space patterns and hole patterns. Since the resist pattern formation method of this disclosure forms a resist film using the composition, it is possible to form a resist pattern with good sensitivity, good CDU, and good resolution. Each step will be described below.

[0132] <Step 1: Film Formation Step> In the film formation step, a resist film is formed on one side of the substrate using the present composition. The resist film is preferably formed by coating. Conventional known substrates can be used as the substrate on which the resist film is formed, such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective film, such as those disclosed in Japanese Patent Publication No. 59-93448, may be formed on the substrate and used. Examples of coating methods for the present composition include rotary coating (spin coating), casting coating, and roll coating. After coating, a soft bake (SB, also called pre-bake (PB)) may be performed to volatilize the solvent in the coating film. The temperature of the SB is preferably 60°C or higher, and more preferably 80°C or higher. The temperature of the SB is preferably 140°C or lower, and more preferably 120°C or lower. The duration of the SB is preferably 5 seconds or more, and more preferably 10 seconds or more. Furthermore, the SB time is preferably 600 seconds or less, and more preferably 300 seconds or less. The average thickness of the formed resist film is preferably 10 to 1,000 nm, and more preferably 20 to 500 nm.

[0133] <Step 2: Exposure Step> In the exposure step, the resist film obtained in the above film formation step is exposed. This exposure is performed by irradiating the resist film with radiation through a photomask, and possibly through an immersion medium such as water. Examples of radiation include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, and gamma rays, depending on the line width of the desired pattern; electron beams, alpha rays, and other charged particle beams. Of these, the radiation irradiated onto the resist film formed using this composition is preferably far ultraviolet light, EUV, or an electron beam; more preferably ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV, or an electron beam; even more preferably ArF excimer laser light, EUV, or an electron beam; even more preferably EUV or an electron beam; and particularly preferably EUV.

[0134] After the exposure described above, it is preferable to perform a post-exposure bake (PEB) to promote the dissociation of acid-dissociable groups in the exposed portion of the resist film by acid generated from a compound that generates acid upon exposure (such as a radiation-sensitive acid generator, a radiation-decaying quencher, or a resin (A) containing a second structural unit). This PEB can increase the difference in solubility in the developer between the exposed and unexposed portions. The PEB temperature is preferably 50°C or higher, more preferably 80°C or higher. Furthermore, the PEB temperature is preferably 180°C or lower, more preferably 130°C or lower. The PEB duration is preferably 5 seconds or more, more preferably 10 seconds or more. Furthermore, the PEB duration is preferably 600 seconds or less, more preferably 300 seconds or less.

[0135] <Step 3: Development Step> In the development step, the exposed resist film is developed. This allows the desired resist pattern to be formed. After development, it is common to wash with a rinsing solution such as water or alcohol and then dry it. The development method in the development step may be alkaline development or organic solvent development.

[0136] In the case of alkaline development, examples of developer solutions include alkaline aqueous solutions containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, aqueous TMAH solutions are preferred, and 2.38% by mass aqueous TMAH solutions are more preferred. In the case of organic solvent development, examples of developer solutions include one or more organic solvents such as hydrocarbons, ethers, esters, ketones, and alcohols, and solvents containing the above organic solvents.

[0137] Examples of development methods include immersing the substrate in a tank filled with developer solution for a certain period of time (dip method), developing by puddling the developer solution onto the substrate surface using surface tension and leaving it still for a certain period of time (paddle method), spraying the developer solution onto the substrate surface (spray method), and continuously dispensing the developer solution while scanning a developer solution dispensing nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispensing method).

[0138] [Intermediate Composition for Radiation-Sensitive Composition] The present invention also relates to an intermediate composition for a radiation-sensitive composition (hereinafter also referred to as "this intermediate composition") which contains a radioactive decay quencher (F) having an iodonium cation represented by formula (B1) described above, an acid additive (D) having a pKa of 3.0 or less, and a solvent (E). The stability of the radioactive decay quencher (F) is improved by the inclusion of a specific acid additive (D) in this intermediate composition.

[0139] <Radio-decayable Quencher (F)> The radio-decayable quencher (F) has an iodonium cation represented by formula (B1) described above, and preferred embodiments and examples of the iodonium cation are the same as preferred embodiments and examples of the iodonium cation constituting the radiosensitive onium salt (B) described above. The radio-decayable quencher (F) also has an organic anion similar to the organic anion constituting the second onium salt described above, and preferably has a carboxylic acid anion. Preferred embodiments and examples of the organic anion are the same as preferred embodiments and examples of the organic anion in the second onium salt described above. The radio-decayable quencher (F) suppresses the diffusion of acid derived from the acid generator generated by exposure in the resist film, thereby suppressing chemical reactions caused by acid in the non-exposed region. It also generates a weak acid that decays upon exposure and does not induce the detachment of acid-dissociable groups.

[0140] <Acid Additive (D)> The acid additive (D) is not particularly limited as long as it is a compound with a pKa of 3.0 or less. The pKa of the acid additive (D) is preferably 2.9 or less, more preferably 2.8 or less, and even more preferably 2.7 or less. Furthermore, in the radiation-sensitive composition, from the viewpoint of suppressing the dissociation of the acid-dissociable groups of the resin (A) by the acid additive (D), it is preferably -1.9 or higher, more preferably -1.0 or higher, even more preferably 0 or higher, and particularly preferably 1.0 or higher. For known pKa values, the known value is adopted. If the pKa is unknown, the acid dissociation constant pKa was determined using ChemDraw (PerkinElmer). If there are two or more pKa values, the lowest pKa value is adopted.

[0141] The boiling point or decomposition temperature of the acid additive (D) is preferably 160°C or higher from the viewpoint of suppressing outgassing. That is, if the acid additive (D) has a boiling point, that boiling point is 160°C or higher, and if the acid additive (D) does not have a boiling point but has a decomposition temperature, that decomposition temperature is 160°C or higher. The boiling point or decomposition temperature of the acid additive (D) is more preferably 180°C or higher, and even more preferably 200°C or higher. There is no particular upper limit to the boiling point or decomposition temperature of the acid additive (D). If the acid additive (D) has a boiling point, the known value shall be adopted if the boiling point of the acid additive (D) is known. If the boiling point is unknown, it shall be measured in accordance with JIS K 0066:1992 "Test Method for Distillation of Chemical Products". If the acid additive (D) does not have a boiling point but has a decomposition temperature, the known value shall be adopted if the decomposition temperature of the acid additive (D) is known. Furthermore, if the decomposition temperature is unknown, it will be measured by thermogravimetric analysis.

[0142] The acid additive (D) preferably satisfies at least one of the following requirements d1 and d2. Requirement d1: -COOH, -OH, and -NHR (where R is a hydrogen atom, a hydrocarbon group, or -C(=O)-R ｄ１ (R ｄ１ Requirement d2: Having two or more groups selected from the group consisting of (where represents a hydrogen atom or a hydrocarbon group): Having a phosphonic acid group

[0143] The preferred range for requirement d1 is the same as requirement c1 for the acid additive (C) described above, and the preferred range is also the same. Similarly, the preferred range for requirement d2 is the same as requirement c2 for the acid additive (C) described above, and the preferred range is also the same.

[0144] As specific examples of acid additives (D), in addition to the compounds exemplified as acid additive (C), the following compounds are also exemplified.

[0145]

[0146] The content of the acid additive (D) in this intermediate composition is preferably 0.1 parts by mass or more and 100 parts by mass or less, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, even more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less, per 100 parts by mass of the radioactive decay quencher (F).

[0147] <Solvent (E)> The solvent (E) is the same as the solvent (E) in the radiation-sensitive composition described above. The solid content concentration of this intermediate composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 15% by mass or less. By setting the solid content concentration of this intermediate composition within the above range, the storage stability of the radiation-decayable quencher (F) is improved.

[0148] This intermediate composition is an intermediate composition for a radiation-sensitive composition, and it is preferable to prepare the radiation-sensitive composition by adding a resin (A), a radiation-sensitive onium salt (B) which is an acid generator, and optionally a solvent (E), etc., to the intermediate composition.

[0149] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. The physical properties in the examples were measured as follows.

[0150] [Measurement of weight-average molecular weight (Mw) and number-average molecular weight (Mn)] GPC columns manufactured by Tosoh Corporation (G2000HXL: 2 columns, G3000HXL: 1 column, G4000HXL: 1 column) were used, and the measurements were performed by gel permeation chromatography (GPC) with monodisperse polystyrene as the standard, under the following analytical conditions: flow rate: 1.0 mL / min, eluent: tetrahydrofuran, sample concentration: 1.0% by mass, sample injection volume: 100 μL, column temperature: 40°C, detector: differential refractometer. The degree of dispersion (Mw / Mn) was calculated from the measured results of Mw and Mn.

[0151] <Synthesis of Resin (A)> The monomers used in the synthesis of each resin (A) in each example and comparative example are shown below.

[0152]

[0153] [Synthesis Example 1] Compounds (M-1) and (M-4) of resin (A-1) were dissolved in 1-methoxy-2-propanol (200 parts by mass relative to the total amount of monomer) in a molar ratio of 40 / 60. Next, azobisisobutyronitrile was added as an initiator at a concentration of 6 mol% relative to the total amount of monomer to prepare a monomer solution. Meanwhile, 1-methoxy-2-propanol (100 parts by mass relative to the total amount of monomer) was added to an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 85°C for a further 3 hours. After the polymerization reaction was complete, the polymerization solution was cooled to room temperature.

[0154] The cooled polymerization solution was added to hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with 100 parts by mass of hexane relative to the polymerization solution, and then dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and the hydrolysis reaction was carried out at 70°C for 6 hours with stirring.

[0155] After the reaction was complete, the residual solvent was removed by distillation, and the obtained solid was dissolved in acetone (100 parts by mass). This solution was added dropwise to 500 parts by mass of water to solidify the resin, and the resulting solid was filtered off. It was dried at 50°C for 12 hours to obtain a white powdered resin (A-1).

[0156] [Synthesis Examples 2-11] Resins (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that the monomer species and ratios were changed as shown in Table 1.

[0157] [Synthesis Example 12] 4-hydroxystyrene, compound (M-4), and compound (M-3) were dissolved in 1-methoxy-2-propanol (200 parts by mass relative to the total amount of monomer) in a molar ratio of 30 / 60 / 10. Next, azobisisobutyronitrile was added as an initiator at a concentration of 6 mol% relative to the total amount of monomer to prepare a monomer solution. Meanwhile, 1-methoxy-2-propanol (100 parts by mass relative to the total amount of monomer) was added to an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 85°C for a further 3 hours. After the polymerization reaction was complete, the polymerization solution was cooled to room temperature.

[0158] The cooled polymerization solution was added to hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with 100 parts by mass of hexane relative to the polymerization solution, and then dried at 50°C for 12 hours to obtain a white powdery resin (A-12).

[0159] [Synthesis Examples 13-15] Resins (A-13) to (A-15) were synthesized in the same manner as in Synthesis Example 12, except that the monomer species and ratios were changed as shown in Table 1. In Table 1, "4HS" represents 4-hydroxystyrene.

[0160]

[0161] <(B) Radiation-sensitive acid generator> Compounds represented by (B-1) to (B-13) below were used as radiation-sensitive acid generators.

[0162]

[0163] <(C) Acid Additives> Compounds represented by (C-1) to (C-20) below were used as acid additives. The pKa and boiling points of the acid additives are shown in Table 2 below. Formulas (C-1) to (C-13) below correspond to (C) acid additives in the present invention, and (C-14) to (C-20) are acid additives for comparative examples. [Acid Dissociation Constant (pKa)] Known values ​​were used for known values. For unknown structures, the acid dissociation constant pKa of the hydroxyl group contained in the additive was determined using ChemDraw (PerkinElmer). For compounds with two or more acid functional groups, the lowest pKa value is listed. [Boiling Point] Known values ​​were used. Compounds with a boiling point exceeding 200°C are indicated with "200<". In Table 2, *1 indicates the decomposition temperature, and *2 indicates the sublimation point.

[0164]

[0165]

[0166] <(F) Radioactive Decay Quencher> Compounds represented by (F-1) to (F-9) below were used as radioactive decay quenchers.

[0167]

[0168] <(E) Organic Solvents> E-1: Propylene glycol monomethyl ether acetate (also known as propylene glycol monomethyl ether acetate) E-2: Methyl 2-hydroxyisobutyrate E-3: Propylene glycol 1-monomethyl ether E-4: Diacetone alcohol

[0169] [Example 1] (A) 100 parts by mass of polymer (A-1), (B) 20 parts by mass of radiation-sensitive acid generator (B-1), (C) 5 parts by mass of acid additive (C-1), (F) 20 mol% of radiation-decaying quencher (F-1) relative to (B-1), (E) 2,000 parts by mass of organic solvent (E-1) and 4,800 parts by mass of organic solvent (E-2) were mixed and then filtered through a filter with a pore size of 0.20 μm to prepare a radiation-sensitive composition (R-1).

[0170] [Examples 2-50 and Comparative Examples 1-11] Radiation-sensitive compositions (R-2) to (R-50) and (CR-1) to (CR-11) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Table 3 below were used.

[0171]

[0172] <Formation of Resist Patterns for Sensitivity and CDU Evaluation> Each of the prepared radiation-sensitive compositions was applied to the surface of a 12-inch silicon wafer with a 20 nm thick underlayer (AL412 (manufactured by Brewer Science)) using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron Limited). After performing a soft bake (SB) at 100°C for 60 seconds, it was cooled at 23°C for 30 seconds to form a 40 nm thick resist film. Next, this resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3300", manufactured by ASML, NA = 0.33, illumination conditions: Conventional s = 0.89). The resist film was subjected to a post-exposure bake (PEB) at 100°C for 60 seconds. Next, the image was developed at 23°C for 30 seconds using a 2.38 wt% TMAH (tetramethylammonium hydroxide) aqueous solution to form a positive-type 50 nm pitch, 25 nm contact hole pattern.

[0173] <Evaluation> The sensitivity and CDU performance of each radiation-sensitive composition were evaluated by measuring each resist pattern formed above according to the method described below. A scanning electron microscope (Hitachi High-Tech Corporation's "CG-5000") was used to measure the length of the resist patterns. The evaluation results are shown in Table 4 below.

[0174] [Sensitivity] In forming the resist pattern described above, the exposure amount used to form the 25 nm contact hole pattern is defined as the optimal exposure amount, and this optimal exposure amount is defined as the sensitivity (mJ / cm²). ２ The sensitivity is set to 56 mJ / cm². A smaller value is better. ２ If the value is less than 56 mJ / cm², it is classified as "S" (very good). ２ More than 58mJ / cm ２ If the value is less than 58 mJ / cm², it is classified as "A" (good). ２More than 61mJ / cm ２ The following cases are classified as "B" (slightly good), 61 mJ / cm². ２ If it exceeded this value, it was judged as "C" (defective).

[0175] [CDU Performance] Using the scanning electron microscope described above, a 25 nm contact hole pattern was observed from above, and a total of 800 measurements were taken at arbitrary points. The dimensional variation (3σ) was determined and defined as the CDU performance (nm). A smaller CDU value indicates less variation in hole diameter over long periods and therefore better performance. CDU performance was judged as follows: less than 3.4 nm = "S" (excellent), 3.4 nm or more and less than 3.6 nm = "A" (good), 3.6 nm or more and less than 3.8 nm = "B" (fairly good), and 3.8 nm or more = "C" (poor).

[0176] <Formation of a resist pattern for storage stability evaluation> (KrF exposure, alkaline development) The radiation-sensitive composition prepared above was applied to the surface of a 12-inch silicon wafer on which a 20 nm thick underlayer film (DUV42 (manufactured by Nissan Chemical Corporation)) had been formed, using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron Limited). After spin coating at 100°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a resist film with a thickness of 45 nm. Next, this resist film was irradiated with KrF light using a KrF exposure machine (model "S210D", manufactured by Nikon Corporation, NA = 0.55, illumination conditions: Annular s = 0.8, mask 150 nm LS). The resist film was subjected to PEB at 90°C for 60 seconds. Then, it was developed using a 2.38 wt% TMAH aqueous solution at 23°C for 30 seconds to form a positive-type 150 nm line and space pattern.

[0177] [Storage Stability] After preparing the radiation-sensitive composition, it was stored at -15°C for two weeks or at 35°C for two weeks. Subsequently, the optimal exposure amount for forming a 150 nm line-and-space pattern was determined in the resist pattern formation by KrF exposure described above. Using the optimal exposure amount of the radiation-sensitive composition stored at -15°C for two weeks as a baseline, if the optimal exposure amount of the radiation-sensitive composition stored at 35°C for two weeks increased sensitivity by 1.0% or more, or decreased sensitivity by 1.0% or more, it was judged as "C". If the sensitivity increased by 0.7% or more but less than 1.0%, or decreased sensitivity by 0.7% or more but less than 1.0%, it was judged as "B". If the change in sensitivity was less than 0.7%, it was judged as "A".

[0178] <Outgassing Performance Evaluation> Each of the radiation-sensitive compositions prepared above was applied to the surface of a 12-inch silicon wafer using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron Limited). After performing soft baking (SB) at 100°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a resist film with a thickness of 40 nm. The resulting resist-coated substrate was cut into a 1 cm x 5 cm rectangle to be used as a measurement sample. The amount of sublimation after heating at 110°C for 10 minutes using an automated P&T system (JTD-505, manufactured by Nippon Analytical Industry Co., Ltd.) was measured using a gas chromatograph-mass spectrometer (GC-MS) (7890B, manufactured by Agilent Technologies). Outgassing performance was defined as "×" if the total outgassing amount was 0.5 μg or more per 1 g of substrate, and "○" if the total outgassing amount was less than 0.5 μg.

[0179]

[0180] As is clear from the results in Table 4, all of the radiation-sensitive compositions in the examples exhibited better storage stability and higher sensitivity compared to the radiation-sensitive compositions in the comparative examples, yielded good CDU (Chemical Discharge Unit), and further suppressed outgassing.

[0181] [Example 51] <Preparation of radioactive decay quencher solution (S-1)> (F) 100 parts by mass of radioactive decay quencher (F-5), (E) 1,000 parts by mass of (E-3) as an organic solvent, and (D) 5 parts by mass of (C-1) as an acid additive were mixed. The resulting mixture was filtered through a filter with a pore size of 0.2 μm to prepare radioactive decay quencher solution (S-1), which is an intermediate composition of the radioactive composition.

[0182] <Preparation of Radiation-Sensitive Composition> The prepared radioactive decay quencher solution (S-1) was stored at -15°C for 2 days or at 60°C for 2 days to obtain radioactive decay quencher solution (S-1α) and radioactive decay quencher solution (S-1β), respectively. Next, (A-1), (B-1), (S-1α) stored at -15°C for 2 days, (E-1), and (E-3) were used to mix the components to the amounts shown in Table 6. The resulting mixture was filtered through a 0.2 μm pore size filter to prepare the radiation-sensitive composition (SR-1α). However, the amount of (S-1α) added was adjusted so that the radioactive decay quencher in the final radiation-sensitive composition (SR-1α) was in the ratio shown in Table 6 to the (B) radiation-sensitive acid generator.

[0183] [Evaluation of Storage Stability of Radiation-Sensitive Composition] A radiation-sensitive composition (SR-1α) was applied to the surface of a 12-inch silicon wafer with a 20 nm thick underlayer (DUV42 (manufactured by Nissan Chemical Corporation)) using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron Limited). After spin coating at 130°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a 50 nm thick resist film. This resist film was irradiated with KrF light using a KrF exposure machine (model "S210D", manufactured by Nikon Corporation, NA = 0.55, illumination conditions: Annular s = 0.8, mask 150 nm LS). PEB was performed at 110°C for 60 seconds. Subsequently, development was performed using a 2.38 wt% TMAH aqueous solution at 23°C for 30 seconds to form a positive-type 150 nm line and space pattern. The optimal exposure amount for forming a 150 nm line and space pattern is defined as Eopα. In the preparation of the radiation-sensitive composition (SR-1α) using the radioactive decay quencher solution (S-1α), the radiation-sensitive composition (SR-1β) was prepared in the same manner as above, except that the radioactive decay quencher solution (S-1β) obtained by storing at 60°C for 2 days was used instead of (S-1α). Next, a positive-type 150 nm line and space pattern was formed in the same manner as above, except that the radiation-sensitive composition (SR-1β) was used instead of the radiation-sensitive composition (SR-1α). The optimal exposure amount for forming the 150 nm line and space pattern is defined as Eopβ. Based on Eopα, if Eopβ was 1.5% or more more sensitive or 1.5% or more less sensitive, it was judged as "C", and if it was less than 1.5% but 1.0% or more more sensitive or less than 1.5% but 1.0% or more less sensitive, it was judged as "B". If the change in sensitivity was less than 1.0%, it was judged as "A".

[0184] [Examples 52-60 and Comparative Examples 12-15] Radioactive decay quencher solutions (S-2) to (S-10) and (SX-1) to (SX-4) were prepared in the same manner as in Example 51, except that the types and amounts of components shown in Table 5 were used. Next, radioactive compositions (SR-2α) to (SR-10α), (SR-2β) to (SR-10β), (SRX-1α) to (SRX-4α) and (SRX-1β) to (SRX-4β) were prepared in the same manner as in Example 51, except that the types and amounts of components shown in Table 6 were used. However, the amount of radioactive decay quencher solution added was such that the ratio of (F) radioactive decay quencher to (B) acid generator in the final radioactive composition was as shown in Table 6.

[0185]

[0186]

[0187] Examples 51 to 60, in which a specific acid additive (D) was added to the radioactive decay quencher solution, showed improved storage stability of the radioactive decay quencher solution compared to the comparative example without the additive.

[0188] The radiation-sensitive composition and resist pattern formation method of the present invention offer improved sensitivity and CDU while maintaining good storage stability and suppressing outgassing. Therefore, these can be suitably used for forming fine resist patterns in the lithography process of various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. The material contains an acid-dissociable group-containing resin (A) and an acid additive (C), wherein the acid-dissociable group-containing resin (A) satisfies one or more of the following requirements 1A and 1B: Requirement 1A: The acid-dissociable group-containing resin (A) further contains structural units derived from a radiation-sensitive onium salt (B), Requirement 1B: It further contains a nonpolymer radiation-sensitive onium salt (B), and the radiation-sensitive onium salt (B) has an iodonium cation represented by the following formula (B1). (In formula (B1), R １ and R ２ Each of these independently represents a substituted or unsubstituted heteroaromatic group or a substituted or unsubstituted aromatic hydrocarbon group, R １ and R ２ If it is an aromatic hydrocarbon group, at least one of them has an electron-withdrawing group.) The acid additive (C) satisfies at least one of the following requirements c1 and c2, has a pKa of 2.8 or less, and a boiling point or decomposition temperature of 160°C or higher. Requirement c1: -COOH, -OH, and -NHR (R is a hydrogen atom, a hydrocarbon group, or -C(=O)-R ｃ１ (R ｃ１ Requirement c2: A radiation-sensitive composition having a phosphonic acid group, having two or more groups selected from the group consisting of (where represents a hydrogen atom or a hydrocarbon group).

2. The radiation-sensitive composition according to claim 1, wherein the iodonium cation represented by formula (B1) is the iodonium cation represented by the following formula (B2). (In formula (B2), Ar １ represents a group obtained by removing (b1+1) hydrogen atoms from a benzene ring or a group obtained by removing (b1+1) hydrogen atoms from a naphthalene ring, and Ar ２ represents a group obtained by removing (b2+1) hydrogen atoms from a benzene ring or a group obtained by removing (b2+1) hydrogen atoms from a naphthalene ring, X １ and X ２ each independently represent a halogen atom, a haloalkyl group, a cyano group, -C(=O)R ｂ１ (R ｂ１ is -NR ｂ１１ ２ or -OR ｂ１２ , R ｂ１１ represents a hydrogen atom or a hydrocarbon group, and R ｂ１２ represents a hydrocarbon group), -SO ２ R ｂ２ (R ｂ２ represents an alkyl group), an alkyl group or an alkoxy group, and at least one of X １ and X ２ is a halogen atom, a haloalkyl group, a cyano group, -C(=O)R ｂ１ (R ｂ１ is -NR ｂ１１ ２ or -OR ｂ１２ , R ｂ１１ represents a hydrogen atom or a hydrocarbon group, and R ｂ１２ represents a hydrocarbon group), or -SO ２ R ｂ２ (R ｂ２ represents an alkyl group), b1 and b2 each independently represent an integer of 0 to 4, provided that at least one of b1 and b2 is 1 to 4.) 3. In formula (B1), R １ and R ２ The radiation-sensitive composition according to claim 1, wherein at least one of the groups is a heteroaromatic group, and each heteroaromatic group is independently a thiophene-2-yl group, a thiophene-3-yl group, a furan-2-yl group, a furan-3-yl group, or a 1H-indole-3-yl group.

4. The radiation-sensitive composition according to claim 1, wherein the acid additive (C) is an aromatic compound represented by the following formula (C1), or squalic acid, oxalic acid, or maleic acid. (In formula (C1), R １１ -COOH, -OH, or -NHR (where R is a hydrogen atom, a hydrocarbon group, or -C(=O)-R) ｃ１ (R ｃ１ (represents a hydrogen atom or hydrocarbon group), R １２ (where n represents a halogen atom, haloalkyl group, hydroxyl group, or carboxyl group, n is 0 or 1, and m is an integer between 0 and 4.) 5. The radiation-sensitive composition according to claim 1, wherein the pKa of the acid additive (C) is -1.9 or higher.

6. The radiation-sensitive composition according to claim 1, wherein the acid-dissociable group-containing resin (A) comprises a structural unit having an acid-dissociable group (first structural unit) and a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring (third structural unit) (excluding the first structural unit).

7. The radiation-sensitive composition according to claim 1, wherein the content of the acid additive (C) per 100 parts by mass of the radiation-sensitive onium salt (B) is 0.1 parts by mass or more and 500 parts by mass or less.

8. The radiation-sensitive composition according to claim 1, wherein the radiation-sensitive onium salt (B) comprises a first onium salt and a second onium salt different from the first onium salt, the first onium salt acting as a radiation-sensitive acid generator and the second onium salt acting as a radiation-decayable quencher.

9. The radiation-sensitive composition according to claim 8, wherein the first onium salt has an iodonium cation represented by formula (B1), and generates an acid that is more acidic than the acid generated by the second onium salt.

10. The radiation-sensitive composition according to claim 8, wherein the second onium salt has an iodonium cation represented by formula (B1) and generates an acid with a lower acidity than the acid generated by the first onium salt.

11. A radioactive decay quencher (F) having an iodonium cation represented by the following formula (B1), (In formula (B1), R １ and R ２ Each of these independently represents a heteroaromatic group that may have substituents or an aromatic hydrocarbon group that may have substituents, and R １ and R ２ If is an aromatic hydrocarbon group, at least one of them has an electron-withdrawing group.) An intermediate composition for a radiation-sensitive composition containing an acid additive (D) having a pKa of 3.0 or less and a solvent (E).

12. An intermediate composition for a radiation-sensitive composition according to claim 11, wherein the boiling point or decomposition temperature of the acid additive (D) is 160°C or higher.

13. An intermediate composition for a radiation-sensitive composition according to claim 11, wherein the acid additive (D) satisfies at least one of the following requirements d1 and d2. Requirement d1: -COOH, -OH, and -NHR (where R is a hydrogen atom, a hydrocarbon group, or -C(=O)-R ｄ１ (R ｄ１ Requirement d2: Having two or more groups selected from the group consisting of (where represents a hydrogen atom or a hydrocarbon group): Having a phosphonic acid group 14. A method for forming a resist pattern, comprising the steps of: forming a resist film on a substrate using a radiation-sensitive composition according to any one of claims 1 to 10; exposing the resist film; and developing the exposed resist film.

15. The resist pattern formation method according to claim 14, wherein the resist film is exposed using extreme ultraviolet light.

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