Radiation-sensitive composition, resist pattern formation method, polymer, and compound

Abstract

A polymer containing a structural unit represented by formula (1) is included in this radiation-sensitive composition. In formula (1), R1 is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. Ar1 is a group obtained by removing (a+2) hydrogen atoms from an aromatic ring. R2 is a group having SO3 - or COO-. Provided that, R2 is bonded to an atom adjacent to the bonding site with the main chain or is bonded to an atom also adjacent to an atom adjacent to the bonding site with the main chain among the atoms constituting the aromatic ring in Ar1. R3 is a substituent. Mb+ is a b-valent cation.

Description

Radiation-sensitive composition, resist pattern forming method, polymer and compound

[0001] [Cross-Reference to Related Applications] This application claims priority to Japanese Patent Application No. 2023-218674, filed on December 25, 2023, the entire contents of which are incorporated herein by reference. The present disclosure relates to a radiation-sensitive composition, a method for forming a resist pattern, a polymer, and a compound.

[0002] In lithography techniques 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 rays such as those from an ArF excimer laser, extreme ultraviolet rays (EUV), electron beams, or the like to generate an acid in the exposed area, and a chemical reaction involving the generated acid causes a difference in the dissolution rate in a developer between the exposed area and the unexposed area, thereby forming a resist pattern on a substrate.

[0003]

[0003] Rapid progress has been made in miniaturizing various electronic device structures, and this has led to a demand for even finer resist patterns in lithography processes. In response to this demand, various studies have been conducted to improve the resolution and rectangularity of resist patterns of chemically amplified radiation-sensitive compositions used in lithographic microfabrication (see, for example, Patent Document 1). Patent Document 1 discloses that a radiation-sensitive composition contains a resin having a repeating unit that decomposes to generate an acid upon irradiation with actinic rays or radiation.

[0004] JP 2011-154216 A

[0005] In photolithography, miniaturization of patterns is being promoted by using short-wavelength radiation such as ArF excimer lasers, or liquid immersion lithography, in which exposure is performed while the space between the lens of an exposure tool and a resist film is filled with a liquid medium. Furthermore, as a next-generation technology, lithography using shorter-wavelength radiation such as electron beams, X-rays, and extreme ultraviolet (EUV) is also being considered. In efforts toward these next-generation technologies, performance equivalent to or better than conventional performance is required in terms of radiation sensitivity and line width roughness (LWR), which is an index of resist pattern quality.

[0006] As resist patterns become finer, slight differences in process conditions such as exposure conditions and development conditions are more likely to affect the shape of the resist pattern, the occurrence of defects, etc. Therefore, radiation-sensitive compositions used in forming resist patterns are required to have a margin that can absorb slight differences in process conditions while maintaining good sensitivity and resist pattern quality, i.e., a wide range of process conditions (hereinafter also referred to as the "process window") that can form a pattern without bridge defects or collapse during the resist pattern formation process.

[0007] The present disclosure has been made in view of the above-mentioned problems, and a primary object of the present disclosure is to provide a radiation-sensitive composition and a method for forming a resist pattern that have high sensitivity, a wide process window, and excellent LWR performance. Another object of the present disclosure is to provide a polymer and a compound that can provide a radiation-sensitive composition that has high sensitivity, a wide process window, and excellent LWR performance.

[0008] The present inventors have found that the above-mentioned problems can be solved by a radiation-sensitive composition containing a polymer having a specific onium salt structure. Specifically, the present disclosure provides the following radiation-sensitive composition, method for forming a resist pattern, polymer, and compound.

[0009] In one aspect, the present disclosure provides a radiation-sensitive composition containing a polymer including a structural unit represented by the following formula (1): (In formula (1), R １ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. １ is a group obtained by removing (a+2) hydrogen atoms from an aromatic ring. ２ is expressed by the following formula (2): (In formula (2), X １ and X ２ are each independently a single bond, —O—, —COO— or —OCO—. １ is a divalent organic group having 1 to 40 carbon atoms. ４ and R ５ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a fluoroalkyl group having 1 to 10 carbon atoms. n1 is an integer of 0 to 3. When n1 is 2 or 3, multiple Y １ are the same or different, and multiple X ２ are the same or different. n2 is an integer of 1 to 10. When n2 is 2 or more, a plurality of R ４ are the same or different, and multiple R ５ are the same or different. － is SO ３ － or COO － "*" indicates Ar １ represents a bond to ２ is Ar １ Among the atoms constituting the aromatic ring in R, it is bonded to an atom adjacent to the bonding position with the main chain, or to an atom further adjacent to the atom adjacent to the bonding position with the main chain. ３ is a substituent. ｂ＋ is a b-valent cation. a is an integer of 0 or more. b is 1 or 2.

[0010] In another aspect, the present disclosure provides a method for forming a resist pattern, the method including the steps of applying the radiation-sensitive composition onto a substrate to form a resist film, exposing the resist film to light, and developing the exposed resist film.

[0011] In another aspect, the present disclosure provides a polymer including a structural unit represented by the above formula (1) and a structural unit having an acid-dissociable group. In another aspect, the present disclosure provides a polymer including a structural unit represented by the following formula (1A): (In formula (1A), R １ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. １ is a group obtained by removing (a+2) hydrogen atoms from an aromatic ring. ２Ａ is a group represented by the above formula (2). ２Ａ is Ar １ Among the atoms constituting the aromatic ring in R, it is bonded to the atom adjacent to the bonding position with the main chain. ３ is a substituent. ｂ＋ is a b-valent cation. a is an integer of 0 or more. b is 1 or 2.

[0012] In another aspect, the present disclosure provides a compound represented by the following formula (3): (In formula (3), R １ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. １ is a group obtained by removing (a+2) hydrogen atoms from an aromatic ring. ２Ａ is a group represented by the above formula (2). ２Ａ is Ar １ Among the atoms constituting the aromatic ring in R, it is bonded to the atom adjacent to the bonding position with the main chain. ３ is a substituent. ｂ＋ is a b-valent cation. a is an integer of 0 or more. b is 1 or 2.

[0013] According to the present disclosure, it is possible to obtain a radiation-sensitive composition that is highly sensitive to radiation, has a wide process window, and exhibits excellent LWR performance. Furthermore, according to the present disclosure, it is possible to obtain a polymer and a compound that can be used to obtain a radiation-sensitive composition that is highly sensitive, has a wide process window, and exhibits excellent LWR performance.

[0014] Matters related to the implementation of the present disclosure will be described in detail below. In this specification, a numerical range described using "to" means that the numerical values ​​before and after "to" are included as the lower limit and upper limit.

[0015] In this specification, the term "hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "chain hydrocarbon group" refers to a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure and is composed solely of a chain structure. However, the chain hydrocarbon group may be saturated or unsaturated. The term "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic hydrocarbon structure as a ring structure and does not contain an aromatic ring structure. However, the alicyclic hydrocarbon group does not necessarily have to be composed solely of an alicyclic hydrocarbon structure and may also contain a chain structure as part of it. The term "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, the aromatic hydrocarbon group does not necessarily have to be composed solely of an aromatic ring structure and may contain a chain structure or an alicyclic hydrocarbon structure as part of it. The term "organic group" refers to an atomic group obtained by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound). The term "aromatic ring" refers to an aromatic hydrocarbon ring and an aromatic heterocycle.

[0016] The "main chain" of a polymer refers to the "trunk" portion of the polymer, which is the longest chain of atoms. It is permissible for this "trunk" portion to contain a ring structure. For example, "having a specific structure in the main chain" means that the specific structure constitutes a part of the main chain of the polymer. A "side chain" refers to a portion branched from the "trunk" of the polymer. A "structural unit" refers to a unit that mainly constitutes the main chain structure, and at least two or more of which are contained in the main chain structure. A structural unit is typically a monomer unit. "(Meth)acrylate" is a term that includes "acrylate" and "methacrylate."

[0017] The expression "substituted or unsubstituted p-valent hydrocarbon group (where p is an integer of 1 or more)" encompasses p-valent hydrocarbon groups (i.e., unsubstituted p-valent hydrocarbon groups) and groups in which p hydrogen atoms have been removed 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 are categorized as "substituted monovalent hydrocarbon groups," and fluoroalkanediyl groups are categorized as "substituted divalent hydrocarbon groups." The same applies to other groups to which "substituted or unsubstituted" is attached.

[0018] <Radiation-Sensitive Composition> The radiation-sensitive composition of the present disclosure (hereinafter also referred to as “the composition”) contains a polymer (hereinafter also referred to as “polymer (C)”) including a structural unit represented by the following formula (1): (In formula (1), R １ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. １ is a group obtained by removing (a+2) hydrogen atoms from an aromatic ring. ２ is a group represented by the following formula (2): ２ is Ar １ Among the atoms constituting the aromatic ring in R, it is bonded to an atom adjacent to the bonding position with the main chain, or to an atom further adjacent to the atom adjacent to the bonding position with the main chain. ３ is a substituent. ｂ＋ is a b-valent cation. a is an integer of 0 or more. b is 1 or 2. (In formula (2), X １ and X ２ are each independently a single bond, —O—, —COO— or —OCO—. １ is a divalent organic group having 1 to 40 carbon atoms. ４ and R ５ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a fluoroalkyl group having 1 to 10 carbon atoms. n1 is an integer of 0 to 3. When n1 is 2 or 3, multiple Y １are the same or different, and multiple X ２ are the same or different. n2 is an integer of 1 to 10. When n2 is 2 or more, a plurality of R ４ are the same or different, and multiple R ５ are the same or different. － is SO ３ － or COO － "*" indicates Ar １ represents a bond with .)

[0019] The structural unit represented by the above formula (1) (hereinafter also referred to as the "first structural unit") has an onium salt structure containing a sulfonate anion or a carboxylate anion and a cation. This first structural unit has an aromatic ring, and the aromatic ring is directly bonded to the main chain. In the first structural unit, a monovalent group having a sulfonate anion or a carboxylate anion (i.e., a group represented by the above formula (2)) is bonded to a specific position on the aromatic ring directly bonded to the main chain. By using a polymer (C) containing such a structural unit as a component of a resist film, the solubility of the polymer in the developer in the unexposed areas is reduced, which in turn contributes to an increase in the contrast between the exposed and unexposed areas, and it is believed that a radiation-sensitive composition with a wide process window can be obtained. The components contained in this composition and the optional components that can be blended are specifically described below. Unless otherwise specified, each component contained in this composition may be used alone or in combination of two or more.

[0020] <Polymer (C)> (First structural unit) In the above formula (1), R １ is preferably a hydrogen atom or a methyl group from the viewpoint of copolymerizability of the monomer that provides the first structural unit.

[0021] Ar １ is a group obtained by removing (a+2) hydrogen atoms from an aromatic ring. The aromatic ring may be a single ring or a condensed ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring. In terms of being able to further increase the sensitivity of the present composition, Ar １Of these, the aromatic ring in the ring is preferably a benzene ring or a naphthalene ring, and from the viewpoint of ease of synthesis of the monomer that provides the first structural unit, a benzene ring is more preferred.

[0022] R ３ Examples of the substituent represented by the formula (I) include an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an aldehyde group, an acyl group, and an ester group. The number of substituents (i.e., the value of a) is not particularly limited and is, for example, 0 to 4, and preferably 0 to 2.

[0023] R ２ is a group represented by the above formula (2). In the above formula (2), Y １ The divalent organic group represented by the formula (I) includes a substituted or unsubstituted divalent hydrocarbon group having 1 to 40 carbon atoms, a methylene group contained in the hydrocarbon group being a heteroatom-containing group (for example, -O-, -S-, -CO-, -COO-, -NH-, -NHCO-, -SO ２ -) (hereinafter referred to as "group R Ｂ "), group R Ｂ and a divalent group in which at least one hydrogen atom of the substituted hydrocarbon group R Ｂ In the above, examples of the substituent include a halogen atom (such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), a hydroxyl group, an alkoxy group, an aldehyde group, an acyl group, and an ester group.

[0024] Examples of the hydrocarbon group having 1 to 40 carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 40 carbon atoms, linear or branched unsaturated hydrocarbon groups having 2 to 40 carbon atoms, alicyclic hydrocarbon groups having 3 to 40 carbon atoms, and aromatic hydrocarbon groups having 6 to 40 carbon atoms.

[0025] Specific examples of linear or branched saturated hydrocarbon groups having 1 to 40 carbon atoms include methylene, ethylene, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl, butane-1,3-diyl, butane-2,3-diyl, hexane-1,6-diyl, etc. Specific examples of linear or branched unsaturated hydrocarbon groups having 2 to 40 carbon atoms include alkenediyl groups such as ethenediyl, propenediyl, and butenediyl; and alkynediyl groups such as ethynediyl, propynediyl, and butynediyl.

[0026] Examples of divalent alicyclic hydrocarbon groups having 3 to 40 carbon atoms include groups having, as a ring structure, an alicyclic monocyclic hydrocarbon structure having 3 to 40 carbon atoms or an alicyclic polycyclic hydrocarbon structure having 6 to 40 carbon atoms. The alicyclic monocyclic hydrocarbon structure having 3 to 40 carbon atoms and the alicyclic polycyclic hydrocarbon structure having 6 to 40 carbon atoms may be either saturated or unsaturated. In addition, the alicyclic polycyclic structure may be any of a bridged structure, a fused ring structure, and a spiro ring structure.

[0027] Examples of the ring contained in the alicyclic monocyclic hydrocarbon structure include cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, etc. The alicyclic polycyclic hydrocarbon structure is preferably a bridged alicyclic saturated hydrocarbon structure or a condensed alicyclic saturated hydrocarbon structure, examples of which include a norbornane structure, a bicyclo[2.2.2]octane structure, an adamantane structure, and a steroid structure.

[0028] Examples of the divalent aromatic hydrocarbon group having 6 to 40 carbon atoms include groups having, as a ring structure, an aromatic monocyclic hydrocarbon structure having 6 to 40 carbon atoms or an aromatic polycyclic hydrocarbon structure having 6 to 40 carbon atoms. Examples of the ring contained in the aromatic hydrocarbon group include a benzene ring, a naphthalene ring, an anthracene ring, an indene ring, and a fluorene ring.

[0029] R ２ The group represented by the formula (R) may be a group in which a methylene group contained in an alicyclic hydrocarbon structure is replaced with a heteroatom-containing group (i.e., an aliphatic heterocyclic group). ２ When R is an aliphatic heterocyclic group,２ Examples of the aliphatic heterocyclic structure contained in R include a cyclic ether structure, a lactone structure, a cyclic acetal structure, a cyclic carbonate structure, and a sultone structure. The aliphatic heterocyclic structure may be either a monocyclic structure or a polycyclic structure. The polycyclic structure may be either a bridged structure, a fused ring structure, or a spiro ring structure. ２ The aliphatic heterocyclic structure that may be possessed by the group represented by the formula (I) may be a combination of two or more of a bridged structure, a fused ring structure, and a spiro ring structure. When the aliphatic heterocyclic structure has a spiro ring structure, the two or more rings constituting the spiro ring structure may be only aliphatic heterocyclic rings, or may be a combination of an aliphatic heterocyclic ring and an alicyclic hydrocarbon ring.

[0030] In the above formula (2), R ４ or R ５ Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and an aromatic hydrocarbon group having 6 to 10 carbon atoms. ４ or R ５ Of these, the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) is preferably a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group. Examples of the fluoroalkyl group having 1 to 10 carbon atoms include groups in which one or more hydrogen atoms in a linear or branched alkyl group have been replaced with fluorine atoms.

[0031] A － In order to enhance the anionicity of R and thereby further improve the sensitivity and LWR performance of the present composition, ４ and R ５ Each of R is preferably a fluorine atom or a linear or branched fluoroalkyl group having 1 to 10 carbon atoms. ４ and R ５ Among these, X is preferably a fluorine atom or a linear or branched perfluoroalkyl group having 1 to 5 carbon atoms, and more preferably a fluorine atom or a trifluoromethyl group. １is preferably —O—, *-COO— or *-OCO—, more preferably *-COO— or *-OCO—. １ n1 is preferably 0 to 2, and more preferably 0 or 1.

[0032] R ２ A preferred specific example of the group is a group represented by the following formula (2A). (In formula (2A), X ３ is —O—, —COO— or —OCO—. ４ represents a single bond, —O—, —COO—, or —OCO—. ２ represents a divalent substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. ３ is a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. ４ｆ and R ５ｆ are each independently a fluorine atom or a fluoroalkyl group having 1 to 10 carbon atoms. n3 is an integer of 0 to 2. When n3 is 2, a plurality of Y ２ are the same or different, and multiple X ４ are the same or different. n4 is an integer of 1 to 10. When n4 is 2 or more, a plurality of R ４ｆ are the same or different, and multiple R ５ｆ are the same or different. － is SO ３ － or COO － "*" indicates Ar １ represents a bond with .)

[0033] In the above formula (2A), Y ２ When Y is a divalent hydrocarbon group having 1 to 20 carbon atoms, examples of the divalent hydrocarbon group include a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, a linear or branched unsaturated hydrocarbon group having 2 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, and an aromatic hydrocarbon group having 6 to 20 carbon atoms. Specific examples of these include Y １ Examples of the substituent include a halogen atom (such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), a hydroxyl group, an alkoxy group, an aldehyde group, an acyl group, and an ester group.

[0034] Y ３ As the divalent hydrocarbon group having 1 to 20 carbon atoms represented by ２ Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms and represented by the formula: ３ is preferably a single bond or an alkanediyl group having 1 to 10 carbon atoms, more preferably a single bond or an alkanediyl group having 1 to 6 carbon atoms, and even more preferably a single bond or an alkanediyl group having 1 to 3 carbon atoms.

[0035] In the above formula (1), R ２ is Ar １ Among the atoms constituting the aromatic ring in the above, Ar is bonded to an atom (specifically, a carbon atom) adjacent to the bonding position with the main chain, or is bonded to an atom (specifically, a carbon atom) further adjacent to the atom adjacent to the bonding position with the main chain. １ When the aromatic ring contained in is a benzene ring, R ２ is bonded to the ortho or meta position of the benzene ring relative to the bonding position to the main chain. １ When the aromatic ring contained in is a naphthalene ring, R ２ is bonded to the 2nd or 3rd position of the naphthalene ring, assuming that the bonding position to the main chain is the 1st position.

[0036] The process window of this composition can be broadened. ２ is Ar １ Among the atoms constituting the aromatic ring, it is preferable that the aromatic ring is bonded to an atom adjacent to the bonding position to the main chain.

[0037] M ｂ＋ The b-valent cation represented by the formula (I) is preferably an organic cation. ｂ＋ is preferably a sulfonium cation, an iodonium cation or an ammonium cation, more preferably a sulfonium cation or an iodonium cation.

[0038] When b in the above formula (1) is 1, M ｂ＋Specific examples of the cations include those represented by the following formula (4), those represented by the following formula (5), and those represented by the following formula (6). (In formula (4), R １ａ and R ２ａ are each independently a monovalent substituent, or R １ａ and R ２ａ are combined together to represent a single bond or a divalent group connecting the rings to which they are attached. ３ａ is a monovalent substituent. a1 and a2 are each independently an integer of 0 to 5. a3 is an integer of 0 to (2×r+5). r is 0 or 1. In formula (5), R ４ａ and R ５ａ are each independently a monovalent substituent. a4 and a5 are each independently an integer of 0 to 5. In formula (6), a6 is an integer of 0 to 7. When a6 is 1, R ６ａ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen group. ６ａ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen group, or a plurality of R ６ａ When two of the groups are combined together, they represent a ring structure having 4 to 20 ring members, which is formed together with the carbon atoms to which they are attached. a7 is an integer of 0 to 6. When a7 is 1, R ７ａ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen group. ７ａ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen group, or a plurality of R ７ａ Two of these are combined together to form a ring structure having 3 to 20 ring members together with the carbon atoms to which they are attached. t1 is an integer of 0 to 3. R ８ａ is a single bond or a divalent organic group having 1 to 20 carbon atoms. t2 is 0 or 1.

[0039] In the above formulas (4) and (5), R １ａ , R ２ａ , R ３ａ , R ４ａ and R ５ａ(Hereinafter referred to as “R １ａ ~R ５ａ ") include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted cycloalkyloxy group, an ester group, an alkylsulfonyl group, a cycloalkylsulfonyl group, a hydroxy group, a carboxy group, a cyano group, and a nitro group.

[0040] R １ａ ~R ５ａ The alkyl group represented by the formula (I) may be linear or branched. The alkyl group preferably has 1 to 10 carbon atoms. １ａ ~R ５ａ The alkyl group represented by the formula (I) preferably has 1 to 5 carbon atoms, and more preferably is a methyl group, an ethyl group, an n-butyl group, or a t-butyl group. １ａ ~R ５ａ Specific examples of when is an alkoxy group include groups having the alkyl group exemplified above in the alkyl group moiety that constitutes the alkoxy group. The alkoxy group is preferably a methoxy group, an ethoxy group, an n-propoxy group, or an n-butoxy group.

[0041] R １ａ ~R ５ａ The cycloalkyl group represented by the formula (I) may be either monocyclic or polycyclic. Among these, examples of monocyclic cycloalkyl groups include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. Examples of polycyclic cycloalkyl groups include a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group. R １ａ ~R ５ａ Specific examples of when R is a cycloalkyloxy group include groups having the above-mentioned cycloalkyl groups in the cycloalkyl group moiety that constitutes the cycloalkyloxy group. １ａ ~R ５ａ The cycloalkyloxy group represented by the following formula is preferably a cyclopentyloxy group or a cyclohexyloxy group.

[0042] R１ａ ~R ５ａ When has a substituent, examples of the substituent include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, and an alkoxy group having 1 to 5 carbon atoms.

[0043] R １ａ ~R ５ａ When R is an ester group (—COOR), examples of the hydrocarbon portion (R) of the ester group include the substituted or unsubstituted alkyl groups or substituted or unsubstituted cycloalkyl groups exemplified above. １ａ ~R ５ａ is an ester group, R １ａ ~R ５ａ is preferably a methoxycarbonyl group, an ethoxycarbonyl group, or an n-butoxycarbonyl group. １ａ ~R ５ａ When R is an alkylsulfonyl group, examples of the alkyl group moiety constituting the alkylsulfonyl group include the substituted or unsubstituted alkyl groups exemplified above. １ａ ~R ５ａ When is a cycloalkylsulfonyl group, the cycloalkyl group moiety constituting the cycloalkylsulfonyl group includes the substituted or unsubstituted cycloalkyl groups exemplified above.

[0044] R １ａ and R ２ａ When these are combined together to represent a divalent group connecting the rings to which they are bonded, examples of the divalent group include -COO-, -OCO-, -CO-, -O-, -SO-, and -SO ２ -, -S-, an alkanediyl group having 1 to 3 carbon atoms, an alkenediyl group having 2 or 3 carbon atoms, -O-, -S-, -COO-, -OCO-, -CO-, -SO-, or -SO between the carbon-carbon bonds of the ethylene group ２ Among these, groups having R １ａ and R ２ａ is preferably a single bond connecting the rings, or forms —O— or —S—.

[0045] Each of a1, a2, and a3 is preferably an integer of 0 to 2. １ａ , R ２ａ and R ３ａ At least one of a4 and a5 is preferably a fluorine atom, an iodine atom, or a trifluoromethyl group. Each of a4 and a5 is preferably an integer of 0 to 2. ４ａ and R ５ａ At least one of the groups is preferably a fluorine atom, an iodine atom, or a trifluoromethyl group.

[0046] In the above formula (6), R ６ａ and R ７ａ The monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) includes a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, -OR ｋ , -COOR ｋ , —O—CO—R ｋ , -O-R ｋｋ -COOR ｋ , -R ｋｋ -CO-R ｋ , -OSO ２ -R ｋ or -SO ２ -R ｋ etc. ｋ is a monovalent hydrocarbon group having 1 to 10 carbon atoms. ｋｋ is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms. The monovalent hydrocarbon group having 1 to 20 carbon atoms is, for example, R ４ or R ５ The monovalent hydrocarbon group represented by R ６ａ and R ７ａ In the above, examples of the substituents that substitute hydrogen atoms of the hydrocarbon group include the above R １ａ ~R ５ａ Examples of the substituents that the group represented by the formula (R) has include the same groups as those exemplified above. ８ａ Examples of the divalent organic group represented by the formula: ６ａ and R ７ａ Examples of such groups include groups in which one hydrogen atom has been removed from the monovalent organic groups having 1 to 20 carbon atoms exemplified above.

[0047] R ６ａ and R ７ａ is a linear or branched monovalent alkyl group, a monovalent fluoroalkyl group, a monovalent aromatic hydrocarbon group, or —OSO ２ -R ｋ or -SO ２ -R ｋ a6 is preferably an integer of 0 to 2, more preferably 0 or 1. a7 is preferably an integer of 0 to 2, more preferably 0 or 1. t2 is preferably 0. t1 is preferably 2 or 3.

[0048] M ｂ＋ Specific examples of M include cations represented by the following formulae: ｂ＋ is not limited to these.

[0049] Specific examples of the first structural unit include structural units represented by the following formulas. However, the first structural unit is not limited to the following specific examples. ｂ＋ " is a b-valent cation, and specific examples thereof include the cations exemplified above.

[0050] From the viewpoint of improving the sensitivity and LWR performance of the present composition, it is preferable that at least a portion of the first structural unit has an iodo group. When the first structural unit includes a structural unit having an iodo group, the cationic moiety in the first structural unit may have an iodo group, or the anionic moiety may have an iodo group. Alternatively, both the cationic moiety and the anionic moiety in the first structural unit may have an iodo group. From the viewpoint of improving the sensitivity and LWR performance of the present composition while suppressing a decrease in solubility, the number of iodo groups in the monomer that provides the first structural unit is preferably 1 to 6, more preferably 1 to 3. The iodo group in the monomer that provides the first structural unit is preferably bonded to an aromatic ring, from the viewpoint of further improving the sensitivity of the present composition.

[0051] Furthermore, in order to improve the sensitivity and LWR performance of the present composition, the first structural unit preferably contains, in the cation moiety, at least one group selected from the group consisting of a fluoroalkyl group and a fluoro group (excluding the fluoro group in the fluoroalkyl group) (hereinafter referred to as the "fluorine-containing group Z １ It is preferable that the cation moiety has a fluorine-containing group Z １ The number of fluorine-containing groups Z (when two or more types are present, the total number of groups) is preferably 1 to 10, more preferably 1 to 6. １ is preferably bonded to an aromatic ring, since this can further increase the sensitivity of the present composition.

[0052] In polymer (C), the content of the first structural unit is preferably 2 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, based on the total amount of structural units constituting polymer (C). Furthermore, the content of the first structural unit is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 35 mol% or less, based on the total amount of structural units constituting polymer (C). Setting the content of the first structural unit within the above range is advantageous in that it can enhance the sensitivity and LWR performance of the composition while further expanding the process margin during pattern formation.

[0053] The polymer (C) preferably constitutes the base resin of the composition. Here, in this specification, "base resin" refers to a polymer component that accounts for 50% by mass or more of the total amount of solids contained in the composition. When the polymer (C) is composed of two or more polymers, the total content of these two or more polymers is preferably 50% by mass or more of the total amount of solids contained in the composition. "Solids" refers to components other than the solvent contained in the composition.

[0054] (Other structural units) The polymer (C) may further contain a structural unit (hereinafter also referred to as "other structural units") different from the first structural unit. Examples of other structural units include a structural unit having an acid-dissociable group (hereinafter also referred to as "second structural unit"); a structural unit having a hydroxyl group bonded to an aromatic ring (hereinafter also referred to as "third structural unit"); a structural unit having a lactone structure, a cyclic carbonate structure, a sultone structure, or a heterocyclic structure combining two or more of these (hereinafter also referred to as "fourth structural unit"); a structural unit having an alcoholic hydroxyl group (hereinafter also referred to as "fifth structural unit"); and the like. In this specification, a structural unit having a hydroxyl group bonded to an aromatic ring and an acid-dissociable group is classified as a second structural unit.

[0055] Second structural unit The acid-dissociable group of the second structural unit is a group that substitutes a hydrogen atom of an acid group such as a carboxy group or a hydroxy group, and is a group that dissociates under the action of an acid. By incorporating a polymer having an acid-dissociable group into the present composition, the acid generated by exposure dissociates the acid-dissociable group to generate an acid group, thereby changing the solubility of the polymer component in a developer. This allows the present composition to be endowed with good lithography properties (such as line write resistance (LWR) and critical dimension uniformity (CDU)) and allows the formation of a good resist pattern.

[0056] The second structural unit is not particularly limited as long as it has an acid-dissociable group. Examples of the second structural unit include a structural unit represented by the following formula (7-1) (hereinafter also referred to as "structural unit (2A)"), a structural unit represented by the following formula (7-2) (hereinafter also referred to as "structural unit (2B)"), and a structural unit represented by the following formula (7-3) (hereinafter also referred to as "structural unit (2C)"). (In formula (7-1), R ７２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ５ R is a divalent chain organic group or an alicyclic hydrocarbon group. ７３ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ７４ and R ７５are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic heterocyclic group, or R ７４ and R ７５ are aligned with each other and R ７４ and R ７５ represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which R is bonded. ７３ When is a hydrogen atom, R ７４ and R ７５ or both of R are independently a substituted or unsubstituted monovalent unsaturated hydrocarbon group, a monovalent aromatic heterocyclic group, or ７４ and R ７５ are aligned with each other and R ７４ and R ７５ represents an alicyclic unsaturated hydrocarbon structure having 3 to 20 carbon atoms formed together with the carbon atom to which it is bonded. g1 is 0 or 1. In formula (7-2), R ７６ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ６ represents a single bond, -O-, -CO-, * ２ -COO- or * ２ -CONH-. ２ " represents a bond to the main chain. ７７ , R ７８ and R ７９ 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. ３５ is a monovalent substituent. g2 is an integer of 0 to 4. In formula (7-3), R ３１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ７ represents a single bond, -O-, -CO-, * ３ -COO- or * ３ -CONH-. ３ " represents a bond to the main chain. ３２ R 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. ３３ and R ３４are 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 ３３ and R ３４ are aligned with each other and R ３３ and R ３４ represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms formed together with the carbon atom to which R is bonded. ３６ is a monovalent substituent. g3 is an integer of 0 to 4.

[0057] In the above formula (7-1), R ７２ In view of the copolymerizability of the monomer that gives the structural unit (2A), R is preferably a hydrogen atom or a methyl group, and more preferably a methyl group. ７６ is preferably a hydrogen atom from the viewpoint of copolymerizability of the monomer that gives the structural unit (2B). ３１ is preferably a hydrogen atom or a methyl group. ６ Or L in formula (7-3) ７ is preferably a single bond, —COO— or —CONH—.

[0058] L in the above formula (7-1) ５ The divalent chain organic group represented by the formula (I) includes a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, a methylene group contained in the chain or branched saturated hydrocarbon group being a heteroatom-containing group (for example, -O-, -S-, -CO-, -COO-, -NH-, -NHCO-, -SO ２ -), and a divalent group having 2 to 20 carbon atoms. ５ Specific and preferred examples of the divalent alicyclic hydrocarbon group represented by R ７３ ~R ７５ , R ７７ ~R ７９ or R ３２ ~R ３４ Examples of the monovalent alicyclic hydrocarbon group represented by the formula (I) include the same groups as those exemplified below. ５ is preferably a chain organic group.

[0059] R ７３ ~R ７５ , R７７ ~R ７９ or R ３２ ~R ３４ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include 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.

[0060] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, and t-butyl; alkenyl groups such as ethenyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl. ７３ ~R ７５ , R ７７ ~R ７９ or R ３２ ~R ３４ The monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) is preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms.

[0061] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monovalent monocyclic alicyclic saturated hydrocarbon groups such as a cyclopentyl group, a cyclohexyl group, a methylcyclopentyl group, an ethylcyclopentyl group, a methylcyclohexyl group, and an ethylcyclohexyl group; monovalent monocyclic unsaturated hydrocarbon groups such as a cyclopentenyl group, a cyclohexenyl group, a methylcyclopentenyl group, and a methylcyclohexenyl group; monovalent polycyclic saturated alicyclic hydrocarbon groups such as a norbornyl group, an adamantyl group, and a tricyclodecyl group; and monovalent polycyclic unsaturated alicyclic hydrocarbon groups such as a norbornenyl group, a tricyclodecenyl group, and an indanyl group.

[0062] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a mesityl group, a naphthyl group, a methylnaphthyl group, an anthryl group, a methylanthryl group, and an indenyl group; and aralkyl groups such as a benzyl group, a phenethyl group, a naphthylmethyl group, and an anthrylmethyl group.

[0063] R ７３ or R ７４Examples of the monovalent unsaturated hydrocarbon group represented by the formula (I) include the above-mentioned monocyclic or polycyclic alicyclic unsaturated hydrocarbon group and aromatic hydrocarbon group. Examples of the monovalent aromatic heterocyclic group include a furyl group and a thienyl group.

[0064] R ７４ and R ７５ are aligned with each other and R ７４ and R ７５ an alicyclic hydrocarbon structure having 3 to 20 carbon atoms formed together with the carbon atom to which R is bonded, and ３３ and R ３４ are aligned with each other and R ３３ and R ３４ Examples of the alicyclic hydrocarbon structure having 3 to 20 carbon atoms constituted together with the carbon atom to which it is bonded include monocyclic alicyclic saturated hydrocarbon structures such as a cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cycloheptane structure, and cyclooctane structure; monocyclic alicyclic unsaturated hydrocarbon structures such as cyclopentene and cyclohexene; and polycyclic alicyclic hydrocarbon structures such as a norbornane structure, adamantane structure, tricyclodecane structure, and tetracyclododecane structure.

[0065] R ７７ ~R ７９ or R ３２ ~R ３４ Examples of the monovalent oxyhydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include the above-mentioned R ７３ ~R ７５ , R ７７ ~R ７９ and R ３２ ~R ３４ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include groups containing an oxygen atom at the bond-side terminal of the groups exemplified by R ７７ ~R ７９ or R ３２ ~R ３４ Of these, the monovalent oxyhydrocarbon group represented by the formula (I) is preferably an alkoxy group, a cycloalkoxy group, or a cycloalkylalkoxy group.

[0066] R ７３ ~R ７５ , R ７７ ~R ７９ or R ３２ ~R３４ When the group represented by R has a substituent, examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), a hydroxyl group, an alkoxy group having 1 to 3 carbon atoms, etc. ７４ and R ７５ are aligned with each other and R ７４ and R ７５ forms an alicyclic hydrocarbon structure having 3 to 20 carbon atoms together with the carbon atom to which it is bonded, or ３３ and R ３４ are aligned with each other and R ３３ and R ３４ When the ring structure is an alicyclic hydrocarbon structure having 3 to 20 carbon atoms together with the carbon atom to which it is bonded, the above-exemplified substituents and alkyl groups may be bonded to the ring.

[0067] R ３５ or R ３６ Examples of the monovalent substituent represented by the formula (I) include an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. g2 and g3 are preferably 0 to 2, and more preferably 0 or 1.

[0068] In order to improve the sensitivity and LWR performance of the present composition, it is preferable that at least a portion of the second structural units contained in the polymer (C) have an aromatic ring in the acid-dissociable group. The aromatic ring in the acid-dissociable group may be either an aromatic hydrocarbon ring or an aromatic heterocycle. Furthermore, the aromatic ring in the acid-dissociable group may be a monocyclic or fused ring. Of these, the aromatic ring in the acid-dissociable group is preferably an aromatic hydrocarbon ring, such as a benzene ring, a naphthalene ring, an anthracene ring, or a phenanthrene ring. In order to improve the sensitivity of the present composition, a benzene ring or a naphthalene ring is preferable, and in terms of ease of synthesis of a monomer that provides the second structural unit, a benzene ring is more preferable.

[0069] At least a portion of the second structural units contain an iodo group and a fluorine-containing group Z １ In the second structural unit, the iodine group and the fluorine-containing group Z are preferably contained in the second structural unit because the sensitivity and LWR performance of the present composition can be improved. １is preferably bonded to an aromatic ring, and the acid-dissociable group has an aromatic ring and the aromatic ring is bonded to an iodine group or a fluorine-containing group Z １ It is more preferable that the iodine group and the fluorine-containing group Z in the monomer that provides the second structural unit are bonded to each other. １ The number of (the total number when two or more kinds are present) is preferably 1 to 10, and more preferably 1 to 6.

[0070] Specific examples of the structural unit (2A) include structural units represented by the following formulas: (In the formula, R ７２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0071] Specific examples of the structural unit (2B) include structural units represented by the following formulas. (In the formula, R ７６ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0072] Specific examples of the structural unit (2C) include structural units represented by the following formulas: (In the formula, R ３１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0073] Other examples of the second structural unit include structural units derived from compounds in which the two carboxy groups of an unsaturated dicarboxylic acid are protected (for example, di-tert-butyl maleate).

[0074] In the polymer (C), the content of the second structural unit is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, based on the total amount of structural units constituting the polymer (C). Furthermore, the content of the second structural unit is preferably 85 mol% or less, more preferably 75 mol% or less, and even more preferably 70 mol% or less, based on the total amount of structural units constituting the polymer (C). By setting the content of the second structural unit within the above range, the difference in dissolution rate in a developer between the exposed and unexposed areas can be increased while maintaining good sensitivity of the composition, thereby enabling the pattern shape of the resist film to be improved.

[0075] The content of the structural unit having an aromatic ring in the acid-dissociable group is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, based on the total amount of structural units constituting the polymer (C), and the content of the structural unit having an aromatic ring in the acid-dissociable group is preferably 85 mol% or less, more preferably 75 mol% or less, and even more preferably 70 mol% or less, based on the total amount of structural units constituting the polymer (C).

[0076] Third structural unit The third structural unit is a structural unit (excluding the first structural unit and the second structural unit) having an aromatic ring and a hydroxy group bonded to the aromatic ring. The polymer (C) further containing the third structural unit is advantageous in that it can improve the resolution of the composition, and is highly effective in suppressing dissolution of unexposed areas into a developer, thereby sufficiently reducing development defects. In particular, polymers having a hydroxy group bonded to an aromatic ring are preferably used in pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV.

[0077] Examples of aromatic rings to which hydroxy groups are bonded include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring. Of these, a benzene ring or a naphthalene ring is preferred, and a benzene ring is more preferred. The number of hydroxy groups bonded to the aromatic ring is not particularly limited. The number of hydroxy groups bonded to the aromatic ring is preferably 1 to 3, and more preferably 1 or 2. The position of the hydroxy group bonded to the aromatic ring is also not particularly limited. For example, when the third structural unit has a hydroxy group bonded to a benzene ring, the bonding position of the hydroxy group on the benzene ring in the third structural unit may be any of the ortho, meta, and para positions relative to other groups.

[0078] The aromatic ring to which the hydroxy group is bonded may further have a substituent different from the hydroxy group bonded thereto, such as an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

[0079] A specific example of the third structural unit is a structural unit represented by the following formula (8). (In formula (8), R ７１ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. ８ represents a single bond, -O-, -CO-, * ６ -COO- or * ６ -CONH-. ６ " represents a bond to the main chain. ６ is a monovalent group having a hydroxyl group bonded to an aromatic ring.

[0080] In the above formula (8), R ７１ is preferably a hydrogen atom or a methyl group from the viewpoint of copolymerizability of the monomer that provides the third structural unit. ５ is a single bond or * ６ —COO— is preferred, and a single bond is more preferred in that it can further increase the sensitivity of the present composition. ６ is preferably a group in which one hydrogen atom has been removed from the ring portion of the aromatic ring to which the hydroxy group is bonded (i.e., a monovalent aromatic ring group substituted with a hydroxy group). ６The aromatic ring in the ring may further have a substituent other than a hydroxy group, specific examples of which are as described above.

[0081] Further specific examples of the third structural unit include structural units represented by the following formulas. (In the formula, R ７１ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group.

[0082] When the polymer (C) contains a third structural unit, the content of the third structural unit is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more, based on the total amount of the structural units constituting the polymer (C). The content of the third structural unit is preferably 60 mol% or less, more preferably 50 mol% or less, and even more preferably 40 mol% or less, based on the total amount of the structural units constituting the polymer (C). By setting the content of the third structural unit within the above range, it is preferable in that the resolution of the composition can be further improved.

[0083] Fourth Structural Unit The fourth structural unit is a structural unit (excluding the first to third structural units) having a lactone structure, a cyclic carbonate structure, a sultone structure, or a ring structure formed by combining two or more of these.

[0084] Specific examples of the fourth structural unit include structural units represented by the following formulas. (In the formula, R Ｌ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0085] When the polymer (C) contains the fourth structural unit, the content of the fourth structural unit is preferably 1 mol% or more, more preferably 2 mol% or more, based on the total amount of the structural units contained in the polymer (C). The content of the fourth structural unit in the polymer (C) is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less, based on the total amount of the structural units contained in the polymer (C).

[0086] Fifth structural unit The fifth structural unit is a structural unit having an alcoholic hydroxyl group (excluding the first to fourth structural units). By introducing the fifth structural unit into polymer (C), the effect of suppressing development defects can be enhanced when a resist pattern is formed using the composition. Here, in this specification, an "alcoholic hydroxyl group" refers to a group having a structure in which a hydroxy group is directly bonded to an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a chain hydrocarbon group or an alicyclic hydrocarbon group.

[0087] The fifth structural unit is preferably a structural unit derived from an unsaturated monomer having an alcoholic hydroxyl group. The structure of the unsaturated monomer that provides the fifth structural unit is not particularly limited. Specific examples of the fifth structural unit include structural units represented by the following formula: (In the formula, R Ａ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0088] When the polymer (C) contains the fifth structural unit, from the viewpoint of sufficiently suppressing development defects in the resist pattern, the content of the fifth structural unit is preferably 1 mol% or more, more preferably 3 mol% or more, based on the total amount of structural units constituting the polymer (C), and the content of the fifth structural unit is preferably 30 mol% or less, more preferably 20 mol% or less, based on the total amount of structural units constituting the polymer (C).

[0089] In addition to the above, examples of structural units possessed by polymer (C) include structural units containing a cyano group, a nitro group, or a sulfonamide group (specifically, a structural unit derived from 2-cyanomethyladamantan-2-yl(meth)acrylate, etc.); structural units containing a non-acid-dissociable hydrocarbon group (specifically, a structural unit derived from substituted or unsubstituted styrene (e.g., a styrene unit, a bromostyrene unit, etc.), a structural unit derived from vinylnaphthalene, a structural unit derived from n-pentyl(meth)acrylate, etc.). The content ratio of these structural units can be appropriately set depending on each structural unit, as long as the effects of the present disclosure are not impaired.

[0090] In order to improve the sensitivity and LWR performance of the present composition, it is preferable that the polymer (C) has an iodine group, and it is particularly preferable that the polymer (C) contains a structural unit having an iodine group. The structural unit having an iodine group may be the first structural unit or another structural unit. In the polymer (C), the content of the structural unit having an iodine group is preferably 1 mol % or more, more preferably 2 mol % or more, and even more preferably 5 mol % or more, based on the total amount of structural units constituting the polymer (C). Furthermore, the content of the structural unit having an iodine group is preferably 80 mol % or less, more preferably 70 mol % or less, based on the total amount of structural units constituting the polymer (C). In the structural unit having an iodine group, it is preferable that the iodine group is bonded to an aromatic ring.

[0091] The weight average molecular weight (Mw) of the polymer (C) measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and even more preferably 4,000 or more. The Mw of the polymer (C) is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, and even more preferably 15,000 or less. By setting the Mw of the polymer (C) within the above range, the coatability of the composition can be improved and development defects can be sufficiently suppressed, which is advantageous.

[0092] The ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the polymer (C) measured by GPC (Mw / Mn, hereinafter also referred to as "dispersity") is preferably 5.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less. Mw / Mn is usually 1.0 or more.

[0093] In the present composition, the content of the polymer (C) is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 85% by mass or more, based on the total amount of solids contained in the present composition.

[0094] The polymer (C) can be synthesized, for example, by polymerizing monomers that provide each structural unit in an appropriate solvent using a known radical polymerization initiator. Examples of the radical polymerization initiator include azo-based radical initiators (e.g., azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile)), peroxide-based radical initiators (e.g., benzoyl peroxide), etc. Examples of the solvent used in the polymerization include linear alkanes, cycloalkanes, aromatic hydrocarbons, halogenated hydrocarbons, saturated carboxylic acid esters, ketones, ethers, and alcohols. The reaction temperature in the polymerization is preferably 40 to 150°C, more preferably 50 to 120°C. The reaction time is preferably 1 to 48 hours, more preferably 2 to 24 hours.

[0095] <Compound represented by formula (3)>

[0096] According to the present disclosure, there is provided a compound represented by the following formula (3): The compound represented by the following formula (3) can be preferably used as a monomer that provides the first structural unit in the polymer (C). (In formula (3), R １ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. １ is a group obtained by removing (a+2) hydrogen atoms from an aromatic ring. ２Ａ is a group represented by the above formula (2). ２Ａ is Ar １ Among the atoms constituting the aromatic ring in R, it is bonded to the atom adjacent to the bonding position with the main chain. ３ is a substituent. ｂ＋ is a b-valent cation. a is an integer of 0 or more. b is 1 or 2.

[0097] In the above formula (3), R １ , Ar １ , R ２Ａ , R ３ , M ｂ＋ , a and b are R in the above formula (1), １ , Ar １ , R ２ , R ３ , Mｂ＋ , a and b have the same meanings as above. ２Ａ is Ar １ Among the atoms that make up the aromatic ring in the main chain, it is bonded to an atom adjacent to the bonding position with the main chain.

[0098] The compound represented by the formula (3) can be synthesized by appropriately combining standard methods of organic chemistry. As an example of a method for synthesizing the compound represented by the formula (3), ２ =CR １ -Ar １ ((R ３ ) ａ a compound having a partial structure corresponding to "-" (hereinafter also referred to as "first compound") and R ２ The compound represented by the above formula (3) can be obtained by reacting a compound having a partial structure corresponding to X in a suitable solvent, if necessary, in the presence of a catalyst to obtain an intermediate product, and then reacting the obtained intermediate product with a sulfonium halide or the like that provides an onium cation moiety. １ In the case of a compound in which X in the above formula (3) is —O—, examples include a method in which a hydroxyl group-containing compound is used as the first compound and a halogen atom-containing compound is used as the second compound; a method in which a halogen atom-containing compound is used as the first compound and a hydroxyl group-containing compound is used as the second compound; １ In the case of a compound in which the group is —COO—, a method of using a carboxy group-containing compound as the first compound and a hydroxy group-containing compound as the second compound can be exemplified. However, the method of synthesizing the compound represented by formula (3) above is not limited to the above.

[0099] <Other Components> The present composition may further contain, together with the polymer (C), a component (hereinafter also referred to as "other component") different from the polymer (C). Examples of the other component include a radiation-sensitive acid generator, a solvent, a high-fluorine-containing polymer, etc.

[0100] (Radiation-Sensitive Acid Generator) As the radiation-sensitive acid generator, an onium salt having an onium cation (preferably a radiation-sensitive onium cation) and an organic anion that is the conjugate base of the acid is preferably used. The organic anion is usually an anion formed by removing a proton from the acid group of an organic acid. In such a radiation-sensitive acid generator, the radiation-sensitive onium cation decomposes under the action of radiation to liberate an organic anion, and the liberated organic anion bonds with hydrogen abstracted from a component contained in the present composition (for example, the radiation-sensitive acid generator itself or a solvent), thereby generating an acid derived from the organic anion.

[0101] The radiation-sensitive acid generator may be a so-called radiation-sensitive acid generator or an acid diffusion controller. Furthermore, the present composition may contain both of these as the radiation-sensitive acid generator. Here, the acid generator is a substance that, upon exposure, generates in the present composition a strong acid capable of cleaving an acid-dissociable group possessed by a component in the radiation-sensitive composition from that component. The acid diffusion controller is a substance that can inhibit the diffusion of the acid derived from the acid generator generated upon exposure within the resist film, thereby inhibiting chemical reactions caused by the acid in unexposed regions. Radiation-sensitive acid generators are classified as acid generators or acid diffusion controllers depending on the strength of their acidity relative to the components in the present composition (specifically, the first structural unit contained in the polymer (C) and the radiation-sensitive acid generator). The level of acidity can be evaluated by the acid dissociation constant (pKa). For example, the acid dissociation constant of the acid generated by the acid diffusion controller is usually −3 or more, preferably −1≦pKa≦7, and more preferably 0≦pKa≦5.

[0102] In terms of enhancing the sensitivity of the present composition, the present composition preferably contains an onium salt in which one or both of the onium cation and organic anion constituting the radiation-sensitive acid generator have an iodine group. １ In this case, the iodo group is preferably bonded to an aromatic ring. １ is preferably bonded to an aromatic ring.

[0103] Acid Generator An acid generator may be incorporated into the composition for the purpose of further improving the sensitivity and CDU performance of the composition. The acid generator generates a strong acid that induces dissociation of an acid-dissociable group under normal conditions upon exposure. The "normal conditions" referred to here refer to post-exposure baking (PEB) at 110°C for 60 seconds. The acid generator referred to here is a component different from the polymer (C). The molecular weight of the acid generator is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0104] The type of acid generator to be incorporated into the composition is not particularly limited, and known radiation-sensitive acid generators used in resist pattern formation can be used as appropriate. The acid generator may be an ionic radiation-sensitive acid generator or a nonionic radiation-sensitive acid generator. An ionic radiation-sensitive acid generator, such as an onium salt composed of a radiation-sensitive onium cation and an organic anion, is preferred. The radiation-sensitive acid generator is preferably a compound that generates an acid (preferably a strong acid such as a sulfonic acid, imidic acid, or methide acid) in the composition under the above-mentioned normal conditions, which has a higher acidity than the acid generated by the acid diffusion controller (more specifically, the photodegradable base), thereby inducing dissociation of the acid-dissociable group.

[0105] When an onium salt is used as the acid generator, from the viewpoint of increasing the sensitivity of the present composition and forming a resist film with excellent lithography performance, the acid generator preferably has a sulfonium cation or an iodonium cation, and more preferably has a triarylsulfonium cation or a diaryliodonium cation. Specific examples of these include the cations represented by the above formula (4), the cations represented by the above formula (5), and the cations represented by the above formula (6). Further specific examples of the radiation-sensitive onium cation contained in the acid generator include the same cations as those given as specific examples of the cations represented by the above formula (4), the cations represented by the above formula (5), and the cations represented by the above formula (6).

[0106] The organic anion of the acid generator is usually an anion obtained by removing a proton from the acid group of the organic acid. The organic anion is not particularly limited, but a sulfonate anion, an imide anion, or a methide anion is preferred in terms of increasing the sensitivity of the composition. For example, specific examples of sulfonate anions include anions represented by the following formula:

[0107]

[0108] When an acid generator is incorporated into the composition, the content of the acid generator is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of polymer (C), from the viewpoint of fully obtaining the effect of improving sensitivity due to the incorporation of the acid generator. Furthermore, from the viewpoint of suppressing the occurrence of defects and development residues due to the acid generator, the content of the acid generator is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, relative to 100 parts by mass of polymer (C).

[0109] Acid Diffusion Controller The acid diffusion controller is a component that can suppress acid-induced chemical reactions in unexposed areas by suppressing the diffusion of acid generated in the resist film upon exposure of the composition. The acid diffusion controller generates a weak acid upon exposure that does not induce dissociation of acid-dissociable groups under the above-mentioned normal conditions. By incorporating such an acid diffusion controller into the composition, the lithography properties of the composition may be further improved. Note that the acid diffusion controller referred to here is a component different from the polymer (C). The molecular weight of the acid diffusion controller is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0110] As the acid diffusion controller, an onium salt composed of a radiation-sensitive onium cation and an organic anion (hereinafter also referred to as a "photodegradable base") can be preferably used. From the viewpoint of improving the lithography properties of the present composition, the photodegradable base is preferably an onium salt that generates a carboxylic acid, a sulfonic acid, or a sulfonamide upon exposure. Furthermore, from the viewpoint of being able to form a resist film with higher lithography performance, an onium salt having a sulfonium cation or an iodonium cation can be preferably used as the photodegradable base.

[0111] Specific examples of the radiation-sensitive onium cation contained in the photodegradable base include the cations represented by the above formula (4), the cations represented by the above formula (5), and the cations represented by the above formula (6). Further specific examples of these include the same cations as those given as specific examples of the cations represented by the above formula (4), the cations represented by the above formula (5), and the cations represented by the above formula (6). Examples of the organic anion contained in the photodegradable base include anions represented by the following formulas:

[0112] When an acid diffusion controller is incorporated into the composition, the content of the acid diffusion controller is preferably 1 part by mass or more, more preferably 2 parts by mass or more, per 100 parts by mass of polymer (C), from the viewpoint of fully obtaining the effects of the incorporation of the acid diffusion controller in improving sensitivity and lithography performance. Furthermore, from the viewpoint of suppressing the occurrence of defects and development residues due to the acid diffusion controller, the content of the acid diffusion controller is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, per 100 parts by mass of polymer (C).

[0113] When an acid diffusion controller is blended in the composition, the content of the acid diffusion controller in the composition is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more, based on the total amount of the radiation-sensitive acid generator and the monomer that provides the first structural unit contained in the composition. Furthermore, the content of the acid diffusion controller is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 35 mol% or less, based on the total amount of the radiation-sensitive acid generator and the monomer that provides the first structural unit contained in the composition. By setting the content of the acid diffusion controller within the above range, the CDU performance of the composition can be further improved.

[0114] (Solvent) The solvent is preferably a solvent capable of dissolving or dispersing the components to be blended in the composition, and an organic solvent can be preferably used. Specific examples of the solvent include alcohols, ethers, ketones, amides, esters, and hydrocarbons.

[0115] Examples of alcohols include aliphatic monoalcohols having 1 to 18 carbon atoms, such as 4-methyl-2-pentanol and n-hexanol; alicyclic monoalcohols having 3 to 18 carbon atoms, such as cyclohexanol; polyhydric alcohols having 2 to 18 carbon atoms, such as 1,2-propylene glycol; and partial ethers of polyhydric alcohols having 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.

[0116] Examples of ketones include chain ketones such as acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, methyl isobutyl ketone, 2-heptanone, ethyl n-butyl ketone, methyl n-hexyl ketone, di-isobutyl ketone, and trimethylnonanone; cyclic ketones such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone; 2,4-pentanedione, acetonylacetone, acetophenone, and diacetone alcohol. Examples of amides include cyclic amides such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain amides such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0117] 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; polycarboxylic 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 having 5 to 12 carbon atoms such as n-pentane and n-hexane; and aromatic hydrocarbons having 6 to 16 carbon atoms such as toluene and xylene.

[0118] Of these, the solvent preferably contains at least one selected from the group consisting of esters and ketones, and more preferably contains at least one selected from the group consisting of polyhydric alcohol partial ether carboxylates and cyclic ketones.

[0119] (High-Fluorine Content Polymer) The high-fluorine content polymer (hereinafter also referred to as "polymer (F)") is a polymer having a higher mass content of fluorine atoms than polymer (C). Polymer (F) is contained in the present composition, for example, as a surface modifier for controlling the hydrophilicity / hydrophobicity of the surface of a resist film, and as a modifier for further improving lithography performance.

[0120] The fluorine atom content of the polymer (F) is not particularly limited as long as it is larger than that of the polymer (C). The fluorine atom content of the polymer (F) is preferably 1% by mass or more, more preferably 4% by mass or more, and even more preferably 7% by mass or more. The fluorine atom content of the polymer (F) is preferably 60% by mass or less, more preferably 40% by mass or less. The fluorine atom content (% by mass) of the polymer is １３ The polymer structure can be determined by C-NMR spectrum measurement or the like, and the amount can be calculated from the structure.

[0121] Examples of the fluorine atom-containing structural unit (hereinafter also referred to as "structural unit (f)") contained in polymer (F) include the structural unit (fa) and structural unit (fb) shown below. Polymer (F) may contain either the structural unit (fa) or the structural unit (fb) as the structural unit (f), or may contain both the structural unit (fa) and the structural unit (fb).

[0122] [Structural Unit (fa)] The structural unit (fa) is a structural unit represented by the following formula (9-1): By adjusting the content of the structural unit (fa) in the polymer (F), the fluorine atom content of the polymer (F) can be adjusted. (In formula (9-1), R Ｃ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, —COO—, or —SO ２ -O-NH-, -CONH- or -O-CO-NH-. Ｅ is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0123] In the above formula (9-1), R CFrom the viewpoint of copolymerizability of the monomer that provides the structural unit (fa), G is preferably a hydrogen atom or a methyl group, and more preferably a methyl group. From the viewpoint of copolymerizability of the monomer that provides the structural unit (fa), G is preferably a single bond or —COO—, and more preferably —COO—.

[0124] R Ｅ Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (R) include a linear or branched alkyl group having 1 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms. E Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include monocyclic or polycyclic alicyclic hydrocarbon groups having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms. Ｅ is preferably a monovalent fluorinated chain hydrocarbon group, more preferably a monovalent fluorinated alkyl group, and even more preferably a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group or a 5,5,5-trifluoro-1,1-diethylpentyl group.

[0125] When the polymer (F) has the structural unit (fa), the content of the structural unit (fa) is preferably 30 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more, based on all structural units constituting the polymer (F). The content of the structural unit (fa) is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less, based on all structural units constituting the polymer (F). By setting the content of the structural unit (fa) within the above range, the mass content of fluorine atoms in the polymer (F) can be more appropriately adjusted, further promoting uneven distribution of fluorine atoms in the surface layer of the resist film. This can further improve the water repellency of the resist film during immersion exposure.

[0126] [Structural Unit (fb)] The structural unit (fb) is a structural unit represented by the following formula (9-2): By including the structural unit (fb), the polymer (F) has improved solubility in an alkaline developer, which can further suppress the occurrence of development defects. (In formula (9-2), R Ｆ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. ５９ is a hydrocarbon group having 1 to 20 carbon atoms and a valence of (s+1), or R ６０ is a group in which an oxygen atom, a sulfur atom, —NR′—, a carbonyl group, —CO—O—, or —CO—NH— is bonded to the terminal of the R ６０ is a single bond or a divalent organic group having 1 to 20 carbon atoms. １２ represents a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms. １１ represents an oxygen atom, —NR″—, —CO—O—*, or —SO ２ -O-*. R" is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. "*" is R ６１ The binding site that binds to R ６１ is a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms. s is an integer of 1 to 3. However, when s is 2 or 3, multiple R ６０ , X １２ , A １１ and R ６１ are the same or different.)

[0127] The structural unit (fb) is divided into a structural unit having an alkali-soluble group and a structural unit having a group that dissociates under the action of an alkali to increase the solubility in an alkali developer (hereinafter, also simply referred to as an “alkali-dissociable group”).

[0128] When the structural unit (fb) has an alkali-soluble group, R ６１ is a hydrogen atom, and A １１ represents an oxygen atom, —COO—*, or —SO ２ O-*. "*" is R ６１ indicates the binding site to X １２ represents a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. １１ is an oxygen atom, X １２ A １１is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which R is bonded. ６０ is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R ６０ , X １２ , A １１ and R ６１ When the structural unit (fb) has an alkali-soluble group, it is possible to increase the affinity for an alkali developer and suppress development defects.

[0129] When the structural unit (fb) has an alkali-dissociable group, R ６１ is a monovalent organic group having 1 to 30 carbon atoms, and A １１ is an oxygen atom, —NR″—, —COO—*, or —SO ２ O-*. "*" is R ６１ indicates the binding site to X １２ is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ６０ is a single bond or a divalent organic group having 1 to 20 carbon atoms. １１ -COO-* or -SO ２ If O-*, then X １２ or R ６１ A １１ A has a fluorine atom on the carbon atom bonded to or adjacent to the carbon atom. １１ is an oxygen atom, X １２ or R ６０ is a single bond, and R ５９ is a hydrocarbon group having 1 to 20 carbon atoms. ６０ A carbonyl group is bonded to the end of the R ６１ is an organic group having a fluorine atom. When s is 2 or 3, a plurality of R ６０ , X １２ , A １１ and R ６１ are the same or different from each other. When the structural unit (fb) has an alkali dissociable group, the surface of the resist film changes from hydrophobic to hydrophilic in the alkali development step. This can increase the affinity to the developer and more efficiently suppress development defects. Examples of the structural unit (fb) having an alkali dissociable group include A１１ is -COO-*, and R ６１ or X １２ It is particularly preferred that both of them have a fluorine atom.

[0130] When polymer (F) has structural unit (fb), the content of structural unit (fb) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more, based on all structural units constituting polymer (F). Furthermore, the content of structural unit (fb) is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less, based on all structural units constituting polymer (F). By setting the content of structural unit (fb) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0131] In addition to the structural unit (fa) and the structural unit (fb), the polymer (F) may also include a structural unit having an acid-dissociable group or a structural unit having an alicyclic hydrocarbon structure represented by the following formula (10) (hereinafter also referred to as "structural unit (g)"). (In the above formula (10), R Ｇ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｇ２ is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0132] In the above formula (10), R Ｇ２ The monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (7-1) to the formula (7-3) includes R ７３ ~R ７５ , R ７７ ~R ７９ or R ３２ ~R ３４ Examples of the monovalent alicyclic hydrocarbon group include the groups exemplified above as the monovalent alicyclic hydrocarbon group represented by the following formula:

[0133] When polymer (F) contains a structural unit represented by formula (10), the content of the structural unit is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, based on all structural units constituting polymer (F). The content of the structural unit represented by formula (10) is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less, based on all structural units constituting polymer (F).

[0134] The Mw of the polymer (F) measured by GPC is preferably 1,000 or more, more preferably 3,000 or more, and even more preferably 4,000 or more. The Mw of the polymer (F) is preferably 50,000 or less, more preferably 30,000 or less, and even more preferably 20,000 or less. The dispersity (Mw / Mn) of the polymer (F) measured by GPC, which is expressed as the ratio of Mn to Mw, is preferably 1.0 or more and 5.0 or less, and more preferably 1.0 or more and 3.0 or less.

[0135] When the composition contains polymer (F), the content of polymer (F) 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, relative to 100 parts by mass of polymer (C). The content of polymer (F) is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, relative to 100 parts by mass of polymer (C).

[0136] (Other Optional Components) The present composition may further contain components (hereinafter also referred to as "other optional components") different from the polymer (C), radiation-sensitive acid generator, solvent, and polymer (F) described above. Examples of the other optional components include surfactants, alicyclic skeleton-containing compounds (e.g., 1-adamantanecarboxylic acid, 2-adamantanone, t-butyl deoxycholate, etc.), sensitizers, and uneven distribution promoters.

[0137] <Method for producing radiation-sensitive composition> The present composition can be produced, for example, by mixing components such as the polymer (C) and, if necessary, a solvent in a desired ratio, and filtering the resulting mixture, preferably using a filter (for example, a filter with a pore size of about 0.2 μm). The solids concentration of the present 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. The solids concentration of the present composition is preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 5% by mass or less. By setting the solids concentration of the present composition within the above range, good coatability can be achieved, and it is advantageous in that a good resist pattern shape can be obtained.

[0138] The composition thus obtained can be used as a positive pattern-forming composition for forming a pattern using an alkaline developer, or as a negative pattern-forming composition for forming a pattern using a developer containing an organic solvent.

[0139] <<Method of Forming Resist Pattern>> The method of forming a resist pattern according to the present disclosure includes a step of applying the present composition to one surface of a substrate (hereinafter also referred to as the "coating step"), a step of exposing the resist film obtained by the coating step (hereinafter also referred to as the "exposure step"), and a step of developing the resist film exposed by the exposure step (hereinafter also referred to as the "developing step"). Examples of patterns formed by the method of forming a resist pattern according to the present disclosure include a line-and-space pattern and a hole pattern. Because the method of forming a resist pattern according to the present disclosure uses the present composition to form a resist film, it is possible to form a resist pattern that has good sensitivity, good LWR and CDU, a wide process window, and good resolution. Each step will be described below.

[0140] [Coating Step] In the coating step, the present composition is applied to one side of a substrate to form a resist film on the substrate. Conventional substrates can be used as the substrate on which the resist film is formed, including, for example, silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective coating, such as that disclosed in JP-A-59-93448, may be formed on the substrate. Examples of methods for applying the present composition include spin coating, casting coating, and roll coating. After coating, a soft bake (SB, also referred to as pre-baking) may be performed to volatilize the solvent in the coating. The SB temperature is preferably 60°C or higher, more preferably 80°C or higher. The SB temperature is preferably 140°C or lower, more preferably 120°C or lower. The SB time is preferably 5 seconds or longer, more preferably 10 seconds or longer. The SB time is preferably 600 seconds or shorter, more preferably 300 seconds or shorter. The average thickness of the resist film formed is preferably 10 to 1,000 nm, and more preferably 20 to 500 nm.

[0141] [Exposure Step] In the exposure step, the resist film obtained in the coating step is exposed. This exposure is carried out by irradiating the resist film with radiation through a photomask, and optionally 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; charged particle beams such as electron beams and alpha rays, depending on the line width of the desired pattern. Among these, the radiation irradiated onto the resist film formed using the present composition is preferably far ultraviolet light, EUV, or electron beams, more preferably ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV, or electron beams, even more preferably ArF excimer laser light, EUV, or electron beams, even more preferably EUV or electron beams, and particularly preferably EUV.

[0142] After the exposure, post-exposure baking (PEB) is preferably performed to promote dissociation of acid-dissociable groups in the exposed portions of the resist film by acid generated from a compound that generates acid upon exposure (such as a radiation-sensitive acid generator). This PEB can increase the difference in solubility in a developer between the exposed and unexposed portions. The PEB temperature is preferably 50°C or higher, more preferably 80°C or higher. The PEB temperature is preferably 180°C or lower, more preferably 130°C or lower. The PEB time is preferably 5 seconds or longer, more preferably 10 seconds or longer. The PEB time is preferably 600 seconds or shorter, more preferably 300 seconds or shorter.

[0143] [Development Step] In the development step, the exposed resist film is developed. This allows a desired resist pattern to be formed. After development, the resist film is generally washed with a rinse liquid such as water or alcohol, and then dried. The development method in the development step may be alkali development or organic solvent development.

[0144] In the case of alkaline development, examples of the developer used for development include an alkaline aqueous solution containing at least one alkaline compound dissolved therein, 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, an aqueous TMAH solution is preferred, and a 2.38% by mass TMAH solution is more preferred. In the case of organic solvent development, examples of the developer include one or more organic solvents such as hydrocarbons, ethers, esters, ketones, and alcohols, and solvents containing the above organic solvents.

[0145] Examples of the developing method include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of developing by piling up the developer on the surface of the substrate by surface tension and leaving it to stand for a certain period of time (puddle method), a method of spraying the developer onto the surface of the substrate (spray method), and a method of continuously discharging the developer while scanning a developer discharging nozzle at a constant speed onto a substrate that is rotating at a constant speed (dynamic dispense method).

[0146] The present disclosure will be specifically described below based on examples, but the present disclosure is not limited to these examples. In the following examples, "parts" and "%" are by mass unless otherwise specified.

[0147] The methods for measuring the physical properties of the polymer are as follows: [Measurement of weight average molecular weight (Mw), number average molecular weight (Mn), and dispersity (Mw / Mn)] Measurements were carried out by gel permeation chromatography (GPC) using Tosoh GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL") under the following analytical conditions: flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, column temperature: 40°C, with monodisperse polystyrene as the standard.

[0148] <Synthesis of Compounds> [Synthesis Example A-1] Synthesis of Compound (A-1) (tris(4-fluorophenyl)sulfonium-2-vinylbenzoic acid-2,2-difluoro-2-sulfoethyl ester)

[0149] 10.0 g of 2-vinylbenzoic acid was dissolved in 45.0 g of tetrahydrofuran, and 16.1 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride was added in an ice bath and stirred for 1 hour. Next, 25.2 g of benzyltrimethylammonium-1,1'-difluoro-2-hydroxyethyl-1-sulfonate and 10.3 g of 4-dimethylaminopyridine were added and stirred for 3 hours. 200 g of dichloromethane, 26.8 g of tris(4-fluorophenyl)sulfonium bromide, and 150 g of 1 mol / L hydrochloric acid were added to the resulting reaction solution and shaken well. The organic layer was washed with saturated aqueous sodium bicarbonate and ultrapure water, and the solvent was distilled off to obtain a crude product. Purification using silica gel column chromatography with a mixed developing solvent of dichloromethane and methanol yielded 33.8 g of the target product (purity 99%, calculated yield 82%).

[0150] <Synthesis of Polymer> The monomers used in synthesizing the polymers used in each of the Examples and Comparative Examples are shown below. In the following synthesis examples, unless otherwise specified, "parts by mass" means a value when the total mass of the monomers used in synthesizing the polymer is taken as 100 parts by mass, and "mol %" means a value when the total number of moles of the monomers used in synthesizing the polymer is taken as 100 mol %.

[0151] (Monomer Providing the First Structural Unit)

[0152] (Monomers that provide other structural units)

[0153]

[0154]

[0155] (Synthesis of Polymers) [Synthesis Example 1] Synthesis of Polymer (C-1) Compound (A-1), compound (B-1), and compound (M-1) were dissolved in 2-butanone (200 parts by mass relative to the total amount of monomers) so that the molar ratio was 10 / 60 / 30. Azobisisobutyronitrile (AIBN) was added as a polymerization initiator at 6 mol % relative to the total amount of monomers to prepare a monomer solution. Separately, 2-butanone (100 parts by mass) was placed in an empty reaction vessel and heated to 80°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours to the reaction vessel containing 2-butanone. Thereafter, the mixture was heated at 80°C for another 3 hours. After completion of the polymerization reaction, the polymerization solution was cooled to room temperature, and then acetonitrile (100 parts by mass) and hexane (600 parts by mass) were added to the polymerization solution and stirred. The lower layer was recovered, and the solvent was removed to obtain Polymer (C-1). The Mw and Mw / Mn of the resulting polymer (C-1) are shown in Table 1.

[0156] [Synthesis Examples 2 to 77] Synthesis of Polymers (C-2) to (C-77) Polymers (C-2) to (C-77) were obtained in the same manner as in Synthesis Example 1, except that the types and amounts of monomers shown in Tables 1 and 2 were added. The Mw and Mw / Mn of each obtained polymer are shown in Tables 1 and 2. The amounts used in Tables 1 and 2 are the molar ratios of all monomers used in the synthesis of each polymer.

[0157]

[0158]

[0159] <Preparation of Radiation-Sensitive Composition> The radiation-sensitive acid generators, acid diffusion controllers, and solvents used in the preparation of the radiation-sensitive compositions are shown below.

[0160] (Radiation-sensitive acid generators) P-1 to P-16: compounds represented by the following formulas (P-1) to (P-16), respectively

[0161]

[0162] (Acid diffusion controller) Q-1 to Q-14: Compounds represented by the following formulas (Q-1) to (Q-14), respectively

[0163]

[0164] (Solvent) E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol 1-monomethyl ether

[0165] [Example 1] 100 parts by mass of polymer (C-1), 20 mol % of acid diffusion controller (Q-1) relative to the amount of the monomer providing the first structural unit contained in 100 parts by mass of polymer (C-1), 4,800 parts by mass of solvent (E-1), and 2,000 parts by mass of solvent (E-2) were blended and mixed. The resulting mixture was then filtered through a membrane filter with a pore size of 0.20 μm to prepare radiation-sensitive composition (R-1).

[0166] [Examples 2 to 104 and Comparative Examples 1 and 2] Radiation-sensitive compositions (R-2) to (R-104), (CR-1) and (CR-2) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Tables 3 and 4 were used.

[0167]

[0168]

[0169] <Formation of Resist Pattern> A radiation-sensitive composition was applied to the surface of a 12-inch silicon wafer on which a 20-nm-thick underlayer film (AL412 (Brewer Science)) had been formed, using a spin coater (CLEAN TRACK ACT12, Tokyo Electron Ltd.). A soft bake (SB) was performed at 130°C for 60 seconds, followed by cooling 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," ASML, NA=0.33, illumination conditions: Conventional s=0.89, mask imecDEFECT32FFR02). Next, post-exposure baking (PEB) was performed at 90° C. for 60 seconds, and then development was performed using a 2.38 wt % aqueous TMAH solution at 23° C. for 30 seconds to form a positive 32 nm line and space pattern.

[0170] <Evaluation> The resist patterns formed as described above were measured according to the methods described below to evaluate the sensitivity, LWR performance, and process window of each radiation-sensitive composition. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-4100") was used to measure the resist patterns. The evaluation results are shown in Tables 5 and 6.

[0171] [Sensitivity] In forming the resist pattern, the exposure amount for forming a 32 nm line and space pattern was defined as the optimum exposure amount, and this optimum exposure amount was used as the sensitivity (mJ / cm ２ The smaller the value, the better the sensitivity.

[0172] [LWR Performance] The resist pattern was observed from above using the scanning electron microscope. The line width was measured at 50 arbitrary points, and the 3 sigma value was calculated from the distribution of the measured values, which was used as the LWR performance. The smaller the value, the better the LWR performance.

[0173] [Process Window] Patterns ranging from low exposure dose to high exposure dose were formed using a mask that forms 32 nm lines and spaces (1L / 1S). Generally, connections between patterns are observed on the low exposure dose side, while defects such as pattern collapse are observed on the high exposure dose side. The difference between the upper and lower limits of the resist dimensions where these defects are not observed is defined as the "CD margin," and the width of the process window was evaluated using the CD margin. The larger the CD margin value, the wider the process window. In this evaluation, a CD margin of 30 nm or more was deemed to be a wide process window and "good," while a CD margin of less than 30 nm was deemed to be a narrow process window and "poor."

[0174]

[0175]

[0176] As is clear from the results in Tables 5 and 6, the radiation-sensitive compositions of the Examples were all superior in sensitivity, LWR performance and CD margin compared to the radiation-sensitive compositions of the Comparative Examples.

[0177] The radiation-sensitive composition and method for forming a resist pattern according to the present disclosure can improve sensitivity, LWR performance, and CD margin compared to conventional methods, and therefore can be suitably used for forming fine resist patterns in the lithography processes of various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. A radiation-sensitive composition containing a polymer containing a structural unit represented by the following formula (1). (In formula (1), R １ is a hydrogen atom, a fluoro group, a methyl group or a trifluoromethyl group. Ar １ is a group obtained by removing (a + 2) hydrogen atoms from an aromatic ring. R ２ is a group represented by the following formula (2) (In formula (2), X １ and X ２ are each independently a single bond, -O-, -COO- or -OCO-. Y １ is a divalent organic group having 1 to 40 carbon atoms. R ４ and R ５ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms. n1 is an integer of 0 to 3. When n1 is 2 or 3, a plurality of Y １ are the same or different, and a plurality of X ２ are the same or different. n2 is an integer of 1 to 10. When n2 is 2 or more, a plurality of R ４ are the same or different, and a plurality of R ５ are the same or different. A － is SO ３ － or COO － is. "*" represents a bond with Ar １ .). However, R ２ is bonded to an atom adjacent to the bonding position with the main chain among the atoms constituting the aromatic ring in Ar １ , or is bonded to an atom further adjacent to the atom adjacent to the bonding position with the main chain. R ３ is a substituent. M ｂ＋ is a b-valent cation. a is an integer of 0 or more. b is 1 or 2.).

2. The radiation-sensitive composition according to claim 1, wherein the polymer contains a structural unit having an acid-dissociable group.

3. The radiation-sensitive composition according to claim 2, wherein the acid-dissociable group contains a structural unit having an aromatic ring.

4. The radiation-sensitive composition according to claim 1, wherein the polymer contains a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring.

5. The radiation-sensitive composition according to claim 1, wherein the polymer has an iodine group.

6. X in the above formula (2) １ The radiation-sensitive composition according to claim 1, wherein is -O-, -COO- or -OCO-.

7. The radiation-sensitive composition according to claim 1, further containing a radiation-sensitive acid generator comprising an onium cation and an organic anion, wherein one or both of the onium cation and the organic anion have an iodine group.

8. The radiation-sensitive composition according to claim 1, further containing a radiation-sensitive acid generator comprising an onium cation and an organic anion, wherein the onium cation has at least one selected from the group consisting of a fluoroalkyl group and a fluoro group (excluding the fluoro groups in the fluoroalkyl group).

9. The radiation-sensitive composition according to claim 1, which is used for forming a resist pattern by exposure to extreme ultraviolet rays.

10. A resist pattern forming method, comprising: forming a resist film on a substrate using the radiation-sensitive composition according to any one of claims 1 to 9; exposing the resist film; and developing the exposed resist film.

11. The resist pattern forming method according to claim 10, wherein the resist film is exposed using extreme ultraviolet rays.

12. A polymer comprising a structural unit represented by the following formula (1) and a structural unit having an acid dissociable group. (In formula (1), R １ is a hydrogen atom, a fluoro group, a methyl group or a trifluoromethyl group. Ar １ is a group obtained by removing (a + 2) hydrogen atoms from an aromatic ring. R ２ is a group represented by the following formula (2) (In formula (2), X １ and X ２ are each independently a single bond, -O-, -COO- or -OCO-. Y １ is a divalent organic group having 1 to 40 carbon atoms. R ４ and R ５ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms. n1 is an integer of 0 to 3. When n1 is 2 or 3, a plurality of Y １ are the same or different, and a plurality of X ２ are the same or different. n2 is an integer of 1 to 10. When n2 is 2 or more, a plurality of R ４ are the same or different, and a plurality of R ５ are the same or different. A － is SO ３ － or COO － is. "*" represents a bond with Ar １ .). However, R ２ is bonded to an atom adjacent to the bonding position with the main chain among the atoms constituting the aromatic ring in Ar １ , or is bonded to an atom further adjacent to the atom adjacent to the bonding position with the main chain. R ３ is a substituent. M ｂ＋ is a b-valent cation. a is an integer of 0 or more. b is 1 or 2.).

13. A polymer containing a structural unit represented by the following formula (1A). (In formula (1A), R １ is a hydrogen atom, a fluoro group, a methyl group or a trifluoromethyl group. Ar １ is a group obtained by removing (a + 2) hydrogen atoms from an aromatic ring. R ２Ａ is a group represented by the following formula (2) (In formula (2), X １ and X ２ are, independently of each other, a single bond, -O-, -COO- or -OCO-. Y １ is a divalent organic group having 1 to 40 carbon atoms. R ４ and R ５ are, independently of each other, a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms. n1 is an integer of 0 to 3. When n1 is 2 or 3, a plurality of Y １ are the same or different, and a plurality of X ２ are the same or different. n2 is an integer of 1 to 10. When n2 is 2 or more, a plurality of R ４ are the same or different, and a plurality of R ５ are the same or different. A － is SO ３ － or COO － is. "*" represents a bond with Ar １ ). However, R ２Ａ is bonded to an atom adjacent to the bonding position with the main chain among the atoms constituting the aromatic ring in Ar １ . R ３ is a substituent. M ｂ＋ is a b-valent cation. a is an integer of 0 or more. b is 1 or 2.) 14. A compound represented by the following formula (3). (In formula (3), R １ is a hydrogen atom, a fluoro group, a methyl group or a trifluoromethyl group. Ar １ is a group obtained by removing (a + 2) hydrogen atoms from an aromatic ring. R ２Ａ is a group represented by the following formula (2) (In formula (2), X １ and X ２ are, independently of each other, a single bond, -O-, -COO- or -OCO-. Y １ is a divalent organic group having 1 to 40 carbon atoms. R ４ and R ５ are, independently of each other, a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms. n1 is an integer of 0 to 3. When n1 is 2 or 3, a plurality of Y １ are the same or different, and a plurality of X ２ are the same or different. n2 is an integer of 1 to 10. When n2 is 2 or more, a plurality of R ４ are the same or different, and a plurality of R ５ are the same or different. A － is SO ３ － or COO － １ . "*" represents a bond with Ar ２Ａ is a group represented by the formula). However, R １ is bonded to an atom adjacent to the bonding position with the main chain among the atoms constituting the aromatic ring in Ar ３ ｂ＋ is a substituent. M ｂ＋ is a b-valent cation. a is an integer of 0 or more. b is 1 or 2.).

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