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

Abstract

This radiation-sensitive composition comprises a polymer (P) including a structural unit having an acid-dissociable group, satisfies at least one among a first requirement, a second requirement, and a third requirement, and includes a specific cation having an acid-dissociable group or the like and an iodine group in at least one of a structural unit derived from a radiation-sensitive onium salt in the polymer (P), a structural unit derived from a radiation-sensitive onium salt in a polymer (Q1), and a radiation-sensitive onium salt (C). First requirement: The polymer (P) includes a structural unit derived from a radiation-sensitive onium salt. Second requirement: A polymer different from the polymer (P) and including a structural unit derived from a radiation-sensitive onium salt is contained. Third requirement: A radiation-sensitive onium salt (C) that is non-polymeric is contained.

Description

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

[0001] [Cross-reference to related applications] This application claims priority to Japanese Patent Application No. 2024-054818 filed on March 28, 2024, and Japanese Patent Application No. 2024-109655 filed on July 8, 2024, the entireties of which are incorporated herein by reference. The present disclosure relates to a radiation-sensitive composition, a method for forming a resist pattern, 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] As the structures of various electronic devices become finer, there is a demand for even finer resist patterns in lithography processes. Furthermore, in response to the demand for even finer resist patterns, various efforts have been made to improve the resolution and resist pattern shape of radiation-sensitive compositions used in lithographic microfabrication (see, for example, Patent Document 1). Patent Document 1 discloses that a resist composition contains a salt composed of a sulfonate anion having a partial structure in which a halogen atom or a haloalkyl group is bonded to a benzene ring, and a cation.

[0004] JP 2023-36004 A

[0005] It is believed that introducing a component having an iodine atom (hereinafter also referred to as an iodine-containing component) into a resist composition can improve sensitivity to radiation. However, according to the inventors' studies, the iodine-containing component does not have sufficient solubility in a developer. Therefore, in the development step of forming a resist pattern, a residual resist film may remain. Furthermore, the residue that did not dissolve in the developer may adhere to the pattern surface, causing defects in the resulting resist pattern. Such development defects increasingly affect the performance of semiconductor devices as resist patterns become finer.

[0006] The present disclosure has been made in consideration 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 are highly sensitive to radiation yet capable of suppressing the occurrence of development defects during resist pattern formation. Another object of the present disclosure is to provide a compound that is highly sensitive to radiation and capable of suppressing the occurrence of development defects during resist pattern formation.

[0007] The present inventors have found that the above-mentioned problems can be solved by a radiation-sensitive composition containing a component derived from a specific onium salt. Specifically, the present disclosure provides the following radiation-sensitive composition, method for forming a resist pattern, and compound.

[0008] In one aspect, the present disclosure provides a radiation-sensitive composition comprising a polymer (P) including a structural unit having an acid-dissociable group, and satisfying one or more of the following first, second, and third requirements: first requirement: the polymer (P) further includes a structural unit derived from a radiation-sensitive onium salt; second requirement: the composition further includes a polymer (Q1) that is different from the polymer (P) and includes a structural unit derived from a radiation-sensitive onium salt; and third requirement: the composition further includes a non-polymeric radiation-sensitive onium salt (C), wherein at least one selected from the group consisting of the structural unit derived from a radiation-sensitive onium salt in the polymer (P), the structural unit derived from a radiation-sensitive onium salt in the polymer (Q1), and the radiation-sensitive onium salt (C) contains a specific cation having an iodo group and at least one group selected from the group consisting of an acid-dissociable group, an amide group, and a sulfonamide group.

[0009] In another aspect, the present disclosure provides a method for forming a resist pattern, the method including the steps of forming a resist film on a substrate using the radiation-sensitive composition, exposing the resist film to light, and developing the exposed resist film.

[0010] In another aspect, the present disclosure provides a compound represented by the following formula (1A): (In formula (1A), R １ａ and R ２ａ is R １ａ is "-X １ -O-CR １１ R １２ -X ２ -R １３ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R ２ａ and (a3) ​​R ３ａAt least one of X is an iodo group. １ is a single bond or a divalent linking group. １１ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. １２ and R １３ is R １２ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R １３ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R １２ and R １３ are combined together to form R １２ and the carbon atom to which R １３ X to which ２ represents a ring structure formed together with X ２ is an oxygen atom or a sulfur atom. a4 is an integer of 1 to 5, and satisfies (a1+a4)≦5. r is 0 or 1. M － is a monovalent anion. １ａ , multiple R ２ａ , multiple R ３ａ , multiple "-X １ -O-CR １１ R １２ -X ２ -R １３ " are the same or different.)

[0011] In another aspect, the present disclosure provides a compound represented by the following formula (1B): (In formula (1B), R １ａ and R ２ａ is R １ａ is "-X １ -COO-CR １４ R １５ R １６ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is a positive number of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R２ａ and (a3) ​​R ３ａ At least one of X is an iodo group. １ is a single bond or a divalent linking group. １４ R is a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aliphatic heterocyclic group. １５ and R １６ are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic heterocyclic group, or R １５ and R １６ are aligned with each other and R １５ and R １６ represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which R is bonded. １４ When is a hydrogen atom, R １５ and R １６ or both of which are, independently of each other, a substituted or unsubstituted monovalent alicyclic unsaturated hydrocarbon group, a substituted or unsubstituted monovalent aromatic hydrocarbon group, or a monovalent aromatic heterocyclic group, or R １５ and R １６ are aligned with each other and R １５ and R １６ represents an alicyclic unsaturated hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which a is bonded. a4 is an integer of 1 to 5, and satisfies (a1+a4)≦5. r is 0 or 1. M － is a monovalent anion having an iodine group. １ａ , multiple R ２ａ , multiple R ３ａ , multiple "-X １ -COO-CR １４ R １５ R １６ " are the same or different.)

[0012] In another aspect, the present disclosure provides a compound represented by the following formula (1C): (In formula (1C), R １ａ and R ２ａ is R １ａ is "-X １ -NR １７ -CO-R１８ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R ２ａ and (a3) ​​R ３ａ At least one of X is an iodo group. １ is a single bond or a divalent linking group. １7 R is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １８ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. a4 is an integer of 1 to 5 and satisfies (a1+a4)≦5. r is 0 or 1. M － is a monovalent anion having an iodine group. １ａ , multiple R ２ａ , multiple R ３ａ , multiple "-X １ -NR １７ -CO-R １８ " are the same or different.)

[0013] In another aspect, the present disclosure provides a compound represented by the following formula (1D): (In formula (1D), R １ａ and R ２ａ is R １ａ is "-X １ -NR １９ -SO ２ -R ２０ " is a substituent different from R ２ａ is a 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. ３ａis a substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R ２ａ and (a3) ​​R ３ａ At least one of X is a monovalent group having a halogen atom. １ is a single bond or a divalent linking group. １９ R is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ２０ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. a4 is an integer of 1 to 5 and satisfies (a1+a4)≦5. r is 0 or 1. M － is a monovalent anion having an iodine group. １ａ , multiple R ２a , multiple R ３ａ , multiple "-X １ -NR １９ -SO ２ -R ２０ " are the same or different.)

[0014] According to the present disclosure, it is possible to obtain a radiation-sensitive composition that is highly sensitive to radiation and that can suppress the occurrence of development defects during resist pattern formation. Also, according to the present disclosure, it is possible to obtain a compound that can be used to obtain a radiation-sensitive composition that is highly sensitive to radiation and that can suppress the occurrence of development defects during resist pattern formation.

[0015] 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.

[0016] 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.

[0017] The "main chain" of a polymer refers to the "backbone" portion of the polymer, which is the longest chain of atoms. It is acceptable for this "backbone" 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 "backbone" of the polymer. A "structural unit" refers to a unit that primarily constitutes the main chain structure, and at least two units are included in the main chain structure. Structural units are typically monomer units. However, "structural units" also include units obtained by reacting a monomer unit having a reactive group with a compound having a functional group reactive with the reactive group, and units obtained by polymerizing a monomer protected with a protecting group such as an alkali-labile group and then deprotecting it by hydrolysis. "(Thio)acetal" is a term that encompasses both "acetal" and "thioacetal." "(Meth)acrylate" is a term that encompasses both "acrylate" and "methacrylate."

[0018] 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.

[0019] <Radiation-Sensitive Composition> The radiation-sensitive composition of the present disclosure (hereinafter also referred to as "the composition") contains a polymer (P) containing a structural unit having an acid-dissociable group. The composition also contains a non-polymeric radiation-sensitive onium salt or a polymer containing a structural unit derived from a radiation-sensitive onium salt (hereinafter also referred to as "onium salt component"). The onium salt component contained in the composition may be either a polymer or a non-polymer, or may contain both a polymer and a non-polymer.

[0020] Specifically, the present composition satisfies one or more of the following first, second, and third requirements, and also satisfies the following fourth requirement. Requirement 1: Polymer (P) further contains a structural unit derived from a radiation-sensitive onium salt. Requirement 2: The composition further contains a polymer (referred to as "polymer (Q)") different from polymer (P) that contains a structural unit derived from a radiation-sensitive onium salt (referred to as "polymer (Q1)"). Requirement 3: The composition further contains a non-polymeric radiation-sensitive onium salt (C). Requirement 4: At least one selected from the group consisting of the structural unit derived from a radiation-sensitive onium salt in polymer (P), the structural unit derived from a radiation-sensitive onium salt in polymer (Q1), and the radiation-sensitive onium salt (C) contains a cation having at least one group selected from the group consisting of an acid-dissociable group, an amide group, and a sulfonamide group, and an iodo group (hereinafter also referred to as "specific cation").

[0021] Hereinafter, the structural unit having an acid-dissociable group in polymer (P) will be referred to as the "first structural unit," and the structural unit derived from a radiation-sensitive onium salt in polymer (P) will be referred to as the "second structural unit." Furthermore, the structural unit derived from a radiation-sensitive onium salt in polymer (Q1) will be referred to as the "structural unit (s)." When the present composition contains polymer (P) containing a second structural unit and polymer (Q1), the second structural unit and the structural unit (s) may be the same structural unit or different structural units.

[0022] Polymer (P) The structure of the polymer (P) contained in the present composition is not particularly limited as long as the present composition satisfies one or more of the first, second, and third requirements described above. Specifically, the polymer (P) may be a polymer containing a first structural unit but not a second structural unit (referred to as "polymer (P1)"), or a polymer containing a first structural unit and a second structural unit (referred to as "polymer (P2)"). Furthermore, the polymer (P1) and the polymer (P2) may further contain structural units different from the first structural unit and the second structural unit (hereinafter also referred to as "other structural units"). The polymer (P) preferably constitutes the base resin in the present composition.

[0023] Herein, the term "base resin" refers to a component that accounts for 30% by mass or more of the total amount of polymer components contained in the composition. The base resin preferably contains a structural unit having an acid-dissociable group in a predetermined proportion or more (e.g., 10% by mole or more), thereby contributing to the solubility of the composition in a developer. The base resin may be composed of two or more polymers. For example, the radiation-sensitive composition may contain, as polymer (P), a first polymer and a second polymer having a different monomer composition from the first polymer, with the first polymer accounting for 50% by mass and the second polymer accounting for 50% by mass, based on the total amount of polymer components contained in the radiation-sensitive composition. In this case, both the first polymer and the second polymer may be polymer (P1), or the first polymer may be polymer (P1) and the second polymer may be polymer (P2).

[0024] Polymer (Q) Polymer (Q) is a component optionally blended into the composition, and differs from polymer (P) in that it does not contain a structural unit having an acid-dissociable group. Similarly, the chemical structure of polymer (Q) is not particularly limited as long as the composition satisfies one or more of the first, second, and third requirements described above. Specifically, polymer (Q) may be a polymer that contains structural unit (s) but does not contain a structural unit having an acid-dissociable group (i.e., polymer (Q1)). Alternatively, polymer (Q) may be a polymer that does not contain either a structural unit having an acid-dissociable group or structural unit (s) (referred to as "polymer (Q2)").

[0025] From the viewpoint of further improving the lithography properties of the present composition by incorporating polymer (Q), polymer (Q) preferably contains a structural unit having a fluorine atom (hereinafter referred to as "structural unit (f)"). When polymer (Q) contains structural unit (f), the polymer is preferably a polymer having a higher mass content of fluorine atoms than polymer (P) (hereinafter also referred to as "high-fluorine content polymer"). The high-fluorine content polymer may be a component incorporated into the present composition, for example, as a water-repellent additive or a modifier for improving lithography performance.

[0026] Radiation-Sensitive Onium Salt (C) The radiation-sensitive onium salt (C), like the polymer (Q), is a component that is optionally blended into the composition. The radiation-sensitive onium salt (C) is a substance that generates an acid upon irradiation with radiation, and typically has a radiation-sensitive onium cation and an organic anion that is the conjugate base of the acid. The organic anion is usually an anion obtained by removing a proton from the acid group of an organic acid. Herein, the term "radiation" encompasses electron beams (visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), etc.) and electromagnetic waves (X-rays, gamma rays, etc.).

[0027] The radiation-sensitive onium salt (C) may be a so-called radiation-sensitive acid generator or an acid diffusion controller. The present composition may also contain both an acid generator and an acid diffusion controller as the radiation-sensitive onium salt (C). 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 an acid derived from the acid generator generated upon exposure in the resist film, thereby inhibiting a chemical reaction caused by the acid in unexposed regions. The acid diffusion controller typically generates in the present composition a weak acid that, upon exposure, does not induce cleavage of an acid-dissociable group possessed by a component in the radiation-sensitive composition.

[0028] The radiation-sensitive onium salt (C) is classified as an acid generator or an acid diffusion controller depending on the strength of its acid relative to the components in the composition (specifically, the monomer that provides the second structural unit in the polymer (P2), the monomer that provides the structural unit (s) in the polymer (Q1), and, in the case where two or more types of radiation-sensitive onium salts (C) are contained, the other radiation-sensitive onium salts). 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.

[0029] The radiation-sensitive onium salt (C) may be an onium salt composed of a specific cation and an organic anion (referred to as "onium salt (C1)"), or an onium salt composed of a radiation-sensitive cation different from the specific cation and an organic anion (referred to as "onium salt (C2)"). The radiation-sensitive onium salt (C) may contain both the onium salt (C1) and the onium salt (C2). Examples of radiation-sensitive cations different from the specific cation (hereinafter also referred to as "other cations") include radiation-sensitive cations that do not have an iodine group; and radiation-sensitive cations that do not have an acid-dissociable group, an amide group, or a sulfonamide group. The molecular weight of the radiation-sensitive onium salt (C) is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0030] In terms of ease of adjusting the sensitivity and lithography properties of the present composition and of providing a high degree of freedom in selecting the onium salt component, the present composition preferably contains a radiation-sensitive onium salt (C) as the onium salt component (i.e., satisfies the third requirement), and more preferably contains an onium salt (C1).

[0031] Fourth Requirement: Of the onium salt components contained in the composition, at least one selected from the group consisting of the second structural unit in the polymer (P), the structural unit (s) in the polymer (Q), and the radiation-sensitive onium salt (C) contains a specific cation. One embodiment of the composition contains at least one selected from the group consisting of the second structural unit in the polymer (P), the structural unit (s) in the polymer (Q), and the radiation-sensitive onium salt (C), wherein the radiation-sensitive onium salt that provides the second structural unit in the polymer (P), the radiation-sensitive onium salt that provides the structural unit (s) in the polymer (Q), and the radiation-sensitive onium salt (C) are each onium salts composed of a radiation-sensitive onium cation and an organic anion that is the conjugate base of an acid, and at least a portion of these onium salts are radiation-sensitive onium salts composed of a specific cation and an organic anion (hereinafter also referred to as "specific onium salts").

[0032] (Specific Cation) In the present composition, the component having the specific cation may be one or more of the second structural unit in the polymer (P2), the structural unit (s) in the polymer (Q1), and the radiation-sensitive onium salt (C). Therefore, for example, only the polymer (P2) may have the specific cation, only the polymer (Q1) may have the specific cation, or only the radiation-sensitive onium salt (C) may have the specific cation. Alternatively, both the polymer (P2) and the radiation-sensitive onium salt (C) may have the specific cation, or both the polymer (Q1) and the radiation-sensitive onium salt (C) may have the specific cation. In terms of further enhancing the sensitivity of the present composition and facilitating sensitivity adjustment, it is preferred that the present composition contain a radiation-sensitive onium salt (C) (i.e., satisfy the third requirement), and that at least a portion of the radiation-sensitive onium salts (C) contained in the present composition have the specific cation.

[0033] The specific cation is not particularly limited as long as it has at least one group selected from the group consisting of an acid-dissociable group, an amide group, and a sulfonamide group, and an iodine group. When the specific cation has an acid-dissociable group, the acid-dissociable group of the specific cation may be a group that substitutes a hydrogen atom of an acid group such as a carboxyl group or a hydroxyl group, and is a group that is released by the action of an acid. When the specific cation has an acid-dissociable group, a preferred specific example of the specific cation is a cation having a (thio)acetal structure or an ester structure and an iodine group, and having the acid-dissociable group in the (thio)acetal structure or the ester structure.

[0034] When the specific cation contains a (thio)acetal structure having an acid-dissociable group, the (thio)acetal structure preferably generates a hydroxyl group by elimination of the acid-dissociable group under the action of an acid. Specific examples of the (thio)acetal structure having an acid-dissociable group include a structure represented by the following formula (2-1): (In formula (2-1), R １１ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. １２ and R １３ is R １２ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R １３ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R １２ and R １３ are combined together to form R １２ and the carbon atom to which R １３ X to which ２ represents an aliphatic heterocyclic structure formed together with X ２ is an oxygen atom or a sulfur atom. "*" represents a bond.)

[0035] When the specific cation contains an ester structure having an acid-dissociable group, the ester structure may be such that the acid-dissociable group is eliminated by the action of an acid to generate a carboxyl group. ２ " (wherein R ２ is an acid-dissociable group. ２is not particularly limited as long as it is a group that dissociates under the action of an acid to generate a carboxy group. ２ " is a structure represented by, for example, R ２ has a tertiary carbon atom, a benzylic carbon atom or an allylic carbon atom, and is bonded to the oxygen atom in the oxycarbonyl group (—COO—) via any of these carbon atoms.

[0036] "-COOR ２ A preferred example of the structure represented by formula (2-2) is a structure represented by the following formula: (In formula (2-2), R １４ R is a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aliphatic heterocyclic group. １５ and R １６ are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic heterocyclic group, or R １５ and R １６ are aligned with each other and R １５ and R １６ represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which R is bonded. １４ When is a hydrogen atom, R １５ and R １６ or both of which are, independently of each other, a substituted or unsubstituted monovalent alicyclic unsaturated hydrocarbon group, a substituted or unsubstituted monovalent aromatic hydrocarbon group, or a monovalent aromatic heterocyclic group, or R １５ and R １６ are aligned with each other and R １５ and R １６ represents an alicyclic unsaturated hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which it is bonded. "*" represents a bond.)

[0037] In the above formula (2-1) and formula (2-2), R １１ ~R １３ , R １４ ~R １６Examples 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.

[0038] The monovalent chain hydrocarbon group having 1 to 20 carbon atoms may be saturated or unsaturated, and may be linear or branched. Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, 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. Among these, R ２１ ~R ２３ The monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) is preferably an alkyl group or an alkenyl group, more preferably an alkyl group having 1 to 4 carbon atoms or an alkenyl group having 2 to 4 carbon atoms.

[0039] 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.

[0040] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, mesityl, naphthyl, methylnaphthyl, anthryl, methylanthryl, and indenyl; and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl. Examples of the monovalent aromatic heterocyclic group include furyl and thienyl.

[0041] R １２ and R １３ are combined together to form R１２ and the carbon atom to which R １３ X to which ２ Examples of the aliphatic heterocyclic structure formed together with R include cyclic ether structures such as a tetrahydrofuran ring structure and a tetrahydropyran ring structure. １４ When is a monovalent aliphatic heterocyclic group, examples of the aliphatic heterocyclic group include a tetrahydrofuranyl group, a tetrahydropyranyl group, and a 7-oxabicyclo[2.2.1]heptyl group.

[0042] R １５ and R １６ are aligned with each other and R １５ and R １６ 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 saturated aliphatic hydrocarbon structures such as a cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cycloheptane structure, and cyclooctane structure; monocyclic unsaturated aliphatic hydrocarbon structures such as cyclopentene and cyclohexene; and polycyclic aliphatic hydrocarbon structures such as a norbornane structure, adamantane structure, tricyclodecane structure, and tetracyclododecane structure.

[0043] R １４ ~R １６ When the group represented by the formula (I) has a substituent, examples of the substituent include a halogen atom, a hydroxyl group, and an alkoxy group having 1 to 3 carbon atoms.

[0044] The specific cation is an amide group (-NR １７ -CO-, R １７ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms), the specific cation preferably has a group represented by the following formula (2-3) as the monovalent group containing an amide group: (In formula (2-3), R １7 is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １8 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. "*" represents a bond.

[0045] In the above formula (2-3), R １７ or R１８ Specific examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (2-1) include R １１ ~R １３ and R in formula (2-2) １４ ~R １６ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms and represented by the formula R １７ or R １８ When the group represented by R has a substituent, examples of the substituent include a halogen atom, a hydroxyl group, a carboxyl group, an alkoxy group having 1 to 3 carbon atoms, a protected hydroxyl group, and a protected carboxyl group. １７ or R １８ has a protected hydroxyl group or a protected carboxyl group as a substituent, the cation having the group represented by the above formula (2-3) is also one form of a cation having an acid-dissociable group.

[0046] R １７ is preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. １８ is preferably a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 12 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms. The bond of the group represented by formula (2-3) is preferably bonded to an aromatic ring, more preferably to a benzene ring or a naphthalene ring.

[0047] The specific cation is a sulfonamide group (-NR １９ -SO ２ -, R １９ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms), the specific cation preferably has a group represented by the following formula (2-4) as the monovalent group containing a sulfonamide group: (In formula (2-4), R １９ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ２０ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. "*" represents a bond.

[0048] In the above formula (2-4), R １９ or R ２０ Specific examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (2-1) include R １１ ~R １３ and R in formula (2-2) １４ ~R １６ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms and represented by the formula R １９ or R ２０ When the group represented by R has a substituent, examples of the substituent include a halogen atom, a hydroxyl group, a carboxyl group, an alkoxy group having 1 to 3 carbon atoms, a protected hydroxyl group, and a protected carboxyl group. １９ or R ２０ has a protected hydroxyl group or a protected carboxyl group as a substituent, the cation having the group represented by the above formula (2-4) is also one form of a cation having an acid-dissociable group.

[0049] R １９ is preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. ２０ is preferably a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 12 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms. The bond of the group represented by formula (2-4) is preferably bonded to an aromatic ring, more preferably to a benzene ring or a naphthalene ring.

[0050] The bonding position of the iodo group in the specific cation is not particularly limited. In order to further enhance the sensitivity and CDU (Critical Dimension Uniformity) of the composition, the specific cation preferably has an aromatic ring and an iodo group bonded to the aromatic ring. Examples of aromatic rings to which an iodo group is 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 iodo groups bonded to one aromatic ring is also not particularly limited. Considering the ease of synthesis of a compound having the specific cation, the number of iodo groups bonded to one aromatic ring is, for example, 1 to 8, preferably 1 to 6, and more preferably 2 to 6. When the specific cation has multiple iodo groups, the multiple iodo groups may be bonded to the same aromatic ring or different aromatic rings.

[0051] In order to further increase the sensitivity of the composition, the specific cation preferably has an arylsulfonium cation structure, more preferably a triarylsulfonium structure. Specifically, the specific cation is preferably represented by the following formula (1-ca): (In formula (1-ca), R １ａ and R ２ａ is R １ａ is "-X １ -R ４ａ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R ２ａ and (a3) ​​R ３ａ At least one of R is an iodo group. ４ａ is a group represented by the above formula (2-1), formula (2-2), formula (2-3) or formula (2-4).１ is a single bond or a divalent linking group. a4 is an integer of 1 to 5, and satisfies (a1+a4)≦5. r is 0 or 1. In the formula, multiple R １ａ , multiple R ２ａ , multiple R ３ａ , multiple "-X １ -R ４ａ " are the same or different.)

[0052] In the above formula (1-ca), R １ａ , R ２ａ or R ３ａ (Hereinafter referred to as “R １ａ ~R ３ａ ") 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 (-COOR, where R is an alkyl group having 1 to 3 carbon atoms), an alkylsulfonyl group, a cycloalkylsulfonyl group, a hydroxy group, a carboxy group, a cyano group, a nitro group, and the like. ２ａ or R ３ａ The substituent represented by "-X １ -R ４ａ However, the R １ａ , R ２ａ and R ３ａ At least one of the groups is an iodine atom.

[0053] R １ａ ~R ３ａ 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 ３ａ 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 ３ａSpecific 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.

[0054] R １ａ ~R ３ａ 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 ３ａ Specific examples of when R is a cycloalkyloxy group include groups having the above-mentioned cycloalkyl groups in the cycloalkyl group moiety constituting the cycloalkyloxy group. １ａ ~R ３ａ The cycloalkyloxy group represented by the following formula is preferably a cyclopentyloxy group or a cyclohexyloxy group.

[0055] R １ａ ~R ３ａ 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.

[0056] R １ａ ~R ３ａ When R is an ester group (—COOR), examples of the ester group include a methoxycarbonyl group, an ethoxycarbonyl group, and a propoxycarbonyl group. １ａ ~R ３ａ When R is an alkylsulfonyl group, the alkyl group moiety constituting the alkylsulfonium group may be the substituted or unsubstituted alkyl groups exemplified above. １ａ ~R ３ａWhen is a cycloalkylsulfonyl group, examples of the alkyl group constituting the cycloalkylsulfonyl group include the substituted or unsubstituted cycloalkyl groups exemplified above.

[0057] 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 The divalent groups which combine to connect the rings to which they are bonded are preferably a single bond or form -O- or -S-.

[0058] The sum of a1, a2, and a3 (= a1 + a2 + a3) is preferably 1 to 8, more preferably 1 to 6, and even more preferably 2 to 6. In addition, R １ａ , R ２ａ and R ３ａ The number of groups each having an iodine atom is preferably 1 to 8, more preferably 1 to 6, and even more preferably 2 to 6.

[0059] X ２ Examples of the divalent linking group represented by the formula (I) include an alkanediyl group having 1 to 6 carbon atoms; an alkenediyl group having 2 to 6 carbon atoms; and an alkanediyl group having 2 to 6 carbon atoms in which a methylene group is -O-, -S-, -COO-, -OCO-, -CO-, -SO- or -SO ２ and a group which is replaced by - and which is bonded to the oxygen atom in the above formula (2-1), the carbonyl group in the above formula (2-2), the nitrogen atom in the above formula (2-3), or the nitrogen atom in the above formula (2-4) via the carbon atom in the methylene group; ４ａ is a group represented by the above formula (2-1), formula (2-3) or formula (2-4), X ２ is preferably a single bond.

[0060] R ４ａ In the formula (2-1), R １１ ~R １３ and R in the above formula (2-2) １４ ~R １６ Specific and preferred examples of R are as described above. ４ａ In the above formula (2-3), R １７ , R １８ and R in the above formula (2-4) １９ , R ２０ Specific and preferred examples are as described above.

[0061] The number of groups represented by the above formula (2-1), formula (2-2), formula (2-3), or formula (2-4) in the specific cation may be 1 or 2 or more. From the viewpoint of maintaining a balance between development contrast and reduction of development defects, the number of groups represented by the above formula (2-1), formula (2-2), formula (2-3), or formula (2-4) in the specific cation is preferably 1 to 4, and more preferably 1 to 3.

[0062] Specific examples of the specific cation include cations represented by the following formulas: However, the specific cation is not limited to the cations shown below.

[0063]

[0064]

[0065]

[0066] (Organic Anion) The organic anion constituting the specific onium salt is usually an anion obtained by removing a proton from an acid group of an organic acid, and examples thereof include a sulfonate anion, an imidate anion, a methide anion, a carboxylate anion, etc. Among these, a sulfonate anion or a carboxylate anion is preferred from the viewpoint of sensitivity.

[0067] The structure of the organic anion constituting the specific onium salt can be appropriately selected depending on the constituent components of the desired radiation-sensitive composition. For example, the organic anion in the radiation-sensitive onium salt that provides the second structural unit in the polymer (P) and the radiation-sensitive onium salt that provides the structural unit (s) in the polymer (Q) is an organic anion having a polymerizable group copolymerizable with a monomer that provides the other structural unit. The polymerizable group is, for example, a group having a polymerizable carbon-carbon unsaturated bond, and specific examples thereof include a (meth)acryloyl group, a phenylvinyl group, and a vinyloxy group. The organic anion in the non-polymer radiation-sensitive onium salt (C) can be appropriately selected from organic anions constituting known acid generators or acid diffusion controllers.

[0068] The organic anion constituting the specific onium salt preferably has a cyclic structure, since this inhibits the diffusion of acid generated by exposure of the composition and allows for the production of a radiation-sensitive composition exhibiting excellent CDU performance. Examples of such cyclic structures include aliphatic hydrocarbon ring structures having 3 to 20 carbon atoms, aliphatic heterocyclic structures having 3 to 20 carbon atoms, and aromatic ring structures having 6 to 20 carbon atoms. Specific examples of these cyclic structures include aliphatic hydrocarbon ring structures having 3 to 20 carbon atoms, and alicyclic polycyclic structures having 6 to 20 carbon atoms. The alicyclic monocyclic structures having 3 to 20 carbon atoms and the alicyclic polycyclic structures having 6 to 20 carbon atoms may be either saturated or unsaturated hydrocarbon structures. The alicyclic polycyclic structures may be either bridged alicyclic hydrocarbon structures or fused alicyclic hydrocarbon structures. Examples of the aliphatic heterocyclic structure having 3 to 20 carbon atoms include a cyclic ether structure, a lactone structure, a cyclic carbonate structure, a sultone structure, and a thioxane structure. The aliphatic heterocyclic structure may be either a monocyclic structure or a polycyclic structure, and may also be any of a bridged structure, a fused ring structure, and a spiro ring structure. Examples of the aromatic ring structure having 6 to 20 carbon atoms include a benzene ring structure, a naphthalene ring structure, an anthracene ring structure, an indene ring structure, and a fluorene ring structure.

[0069] In order to further enhance the sensitivity of the composition, it is preferable that the organic anion constituting the specific onium salt has an iodo group. In this case, the bonding position of the iodo group is not particularly limited, but in order to further enhance the sensitivity and CDU performance of the composition, it is preferable that the organic anion constituting the specific onium salt has an aromatic ring and an iodo group bonded to the aromatic ring.

[0070] In the organic anion constituting the specific onium salt, examples of the aromatic ring to which an iodo group is 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 iodo groups bonded to one aromatic ring is also not particularly limited. In consideration of the ease of synthesis of the specific onium salt, the number of iodo groups bonded to one aromatic ring is, for example, 1 to 8, preferably 1 to 6, and more preferably 2 to 6. When the organic anion has multiple iodo groups, the multiple iodo groups may be bonded to the same aromatic ring or different aromatic rings.

[0071] A preferred example of the specific onium salt is a compound represented by the following formula (1). (In formula (1), R １ａ , R ２ａ , R ３ａ , X １ , R ４ａ , a1, a2, a3, a4 and r are R in the above formula (1-ca), respectively. １ａ , R ２ａ , R ３ａ , X １ , R ４ａ , a1, a2, a3, a4 and r. － is a monovalent anion, where R ４ａ is a group represented by the above formula (2-2), M － has an iodo group.)

[0072] In the above formula (1), R １ａ , R ２ａ , R ３ａ , X １ , R ４ａ, a1, a2, a3, a4 and r are R in the above formula (1-ca), respectively. １ａ , R ２ａ , R ３ａ , X １ , R ４ａ , a1, a2, a3, a4 and r. － As a specific example of the organic anion, the above description of the organic anion is applied.

[0073] Specific embodiments of the radiation-sensitive composition that satisfy one or more of the first, second, and third requirements and the fourth requirement include the following embodiments [1] to [8] and a combination of two or more of these embodiments. Embodiment [1]: The radiation-sensitive composition contains a polymer (P1) and a radiation-sensitive onium salt (C), wherein the radiation-sensitive onium salt (C) contains an acid generator and an acid diffusion controller, and the acid generator is an onium salt (C1) composed of a specific cation and an organic anion. Embodiment [2]: The radiation-sensitive onium salt (C), wherein the radiation-sensitive onium salt (C) contains an acid generator and an acid diffusion controller, and the acid diffusion controller is an onium salt (C1) composed of a specific cation and an organic anion. Embodiment [3]: The radiation-sensitive composition contains a polymer (P1), a polymer (Q1), and a radiation-sensitive onium salt (C), wherein the polymer (Q1) functions as an acid generator, and the radiation-sensitive onium salt (C) contains an acid diffusion controller. Aspect [4]: ​​The composition contains a polymer (P1), a polymer (Q1), and a radiation-sensitive onium salt (C), wherein the polymer (Q1) functions as an acid diffusion controller, and the radiation-sensitive onium salt (C) contains an acid generator. Aspect [5]: The composition contains a polymer (P2) and a radiation-sensitive onium salt (C), wherein the polymer (P2) functions as an acid generator, and the radiation-sensitive onium salt (C) contains an acid diffusion controller. Aspect [6]: The composition contains a polymer (P2) and a radiation-sensitive onium salt (C), wherein the polymer (P2) functions as an acid diffusion controller, and the radiation-sensitive onium salt (C) contains an acid generator. Aspect [7]: The composition contains a polymer (P2), wherein the polymer (P2) contains multiple types of structural units as second structural units, wherein some of the multiple types of structural units function as acid generators, and the rest function as acid diffusion controllers. Aspect [8]: The polymer (Q1) is contained, and the polymer (Q1) contains a plurality of structural units as the structural unit (s), and some of the plurality of structural units function as an acid generator, and the rest function as an acid diffusion controller.

[0074] The radiation-sensitive compositions of the above-mentioned embodiments [1] to [8] may further contain other solid components (such as an acid generator, an acid diffusion controller, or a high-fluorine-content polymer) in addition to the components contained in each embodiment. For example, the radiation-sensitive compositions of the above-mentioned embodiments [1] to [8] may further contain a polymer (Q), and the radiation-sensitive onium salt (C) of the present invention may further contain an acid generator. In this specification, the term "solid components" refers to components other than the solvent contained in the present composition.

[0075] Here, it is considered that by incorporating an iodine-containing component as an onium salt component into the radiation-sensitive composition, it is possible to improve the sensitivity of the radiation-sensitive composition to radiation.On the other hand, when incorporating an iodine-containing component into the radiation-sensitive composition, the dissolution rate of the iodine-containing component in the developer is not sufficiently fast, so that in the development step of forming a resist pattern, the region of the resist film that should be dissolved in the developer is not sufficiently dissolved in the developer, resulting in the undissolved resist film and the occurrence of development defects.In this regard, the present composition using a specific onium salt (non-polymer) or a polymer containing a structural unit derived from the specific onium salt can reduce the occurrence of development defects while increasing the sensitivity of the radiation-sensitive composition by introducing iodine atoms. Although the reason why the present composition can simultaneously achieve high sensitivity of the radiation-sensitive composition and suppression of development defects is not clear, one hypothesis is that the introduction of an acid-dissociable group, an amide group, or a sulfonamide group, together with an iodine atom, into the onium salt component ensures that the non-exposed areas are less likely to dissolve in a developer, while the increased polarity of the onium salt component improves the solubility of the exposed areas in a developer. However, this hypothesis does not in any way limit the present invention.

[0076] Next, the components contained in the composition and the optional components to be blended will be described in detail. Unless otherwise specified, each component contained in the composition may be used alone or in combination of two or more.

[0077] <Polymer (P)>

[0078] (First structural unit) The first structural unit is a structural unit having an acid-dissociable group. The first structural unit is usually introduced into the polymer (P) to adjust the sensitivity of the polymer (P) and its solubility in a developer. The acid-dissociable group of the first structural unit is a group that substitutes a hydrogen atom of an acid group such as a carboxy group or a hydroxy group, and may be a group that is released by the action of an acid. In this specification, a structural unit having an acid-dissociable group and a hydroxy group bonded to an aromatic ring is classified as a first structural unit. The first structural unit differs from the second structural unit in that it does not have an onium salt structure.

[0079] The first structural unit is not particularly limited as long as it has an acid-dissociable group. Examples of the first structural unit include a structural unit represented by the following formula (1-1) (hereinafter also referred to as "structural unit (1a)"), a structural unit represented by the following formula (1-2) (hereinafter also referred to as "structural unit (1b)"), and a structural unit represented by the following formula (1-3) (hereinafter also referred to as "structural unit (1c)"). (In formula (1-1), R ３０ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ R is a divalent chain organic group or an alicyclic hydrocarbon group. ３１ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３２ and R ３３ are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic heterocyclic group, or R ３２ and R ３３ are aligned with each other and R ３２ and R ３３ represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which R is bonded. ３１ When is a hydrogen atom, R ３２ and R ３３ or both of which are, independently of each other, a substituted or unsubstituted monovalent alicyclic unsaturated hydrocarbon group, a substituted or unsubstituted monovalent aromatic hydrocarbon group, or a monovalent aromatic heterocyclic group, or R ３２ and R ３３ are aligned with each other and R ３２ and R３３ represents an alicyclic unsaturated hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which it is bonded. g1 is 0 or 1. In formula (1-2), R ３０ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ３ represents a single bond, -O-, -CO-, * ２ -COO- or * ２ -CONH-. ２ " represents a bond to the main chain. ３４ , R ３５ and R ３６ 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. ２８ is -OC(R ３４ ) (R ３５ ) (R ３６ g2 is an integer of 0 to 4. In formula (1-3), R ３０ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ４ represents a single bond, -O-, -CO-, * ３ -COO- or * ３ -CONH-. ３ " represents a bond to the main chain. ３７ 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. ３８ and R ３９ are each independently a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted monovalent oxyhydrocarbon group having 1 to 20 carbon atoms, or R ３８ and R ３９ are aligned with each other and R ３８ and R ３９ represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms formed together with the carbon atom to which R is bonded. ２９ is -COO-C(R ３７ ) (R ３８ ) (R ３９ g3 is an integer of 0 to 4.

[0080] In the above formula (1-1), R ３０ In view of the copolymerizability of the monomer that gives the structural unit (1a), R is preferably a hydrogen atom or a methyl group, and more preferably a methyl group. ３０ is preferably a hydrogen atom from the viewpoint of copolymerizability of the monomer that gives the structural unit (1b). ３０ is preferably a hydrogen atom or a methyl group. ３ Or L in formula (1-3) ４ is preferably a single bond, —COO— or —CONH—.

[0081] L in the above formula (1-1) ２ 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. ２ Specific and preferred examples of the divalent alicyclic hydrocarbon group represented by the formula (2-2) include R １４ ~R １６ Examples of the monovalent alicyclic hydrocarbon group include groups in which one hydrogen atom has been removed from the groups exemplified as the monovalent alicyclic hydrocarbon group represented by the formula: ２ is preferably a chain organic group.

[0082] R in the above formulas (1-1) to (1-3) ３１ ~R ３３ , R ３４ ~R ３６ or R ３７ ~R ３９ Specific examples of the group represented by the formula (2-2) include R １４ ~R １６ Examples of the group represented by the formula (1-2) include the same groups as those exemplified above. ２８ , R in the above formula (1-3) ２９ Specific examples of R in the above formula (1) include １ａ ~R ３ａSpecific examples of g2 and g3 include the same groups as those exemplified above. Each of g2 and g3 is preferably 0 to 2.

[0083] In order to improve the sensitivity and CDU performance of the present composition in a well-balanced manner, it is preferable that at least a part of the first structural units contained in the polymer (P) have an iodine atom. From the viewpoint of sufficiently enhancing the effect of improving the sensitivity of the present composition, it is preferable that the iodine atom in the first structural unit is bonded to an aromatic ring. Furthermore, from the viewpoint of further enhancing the effect of improving CDU performance, it is more preferable that the acid-dissociable group in the first structural unit has an aromatic ring, and that the iodine atom is bonded to the aromatic ring. Specifically, as the first structural unit, R in the above formula (1-1) ３１ is a structural unit in which R in the above formula (1-2) is an iodophenyl group ３４ is an iodophenyl group, and R ３７ It is preferable that the compound contains at least one structural unit in which the structural unit is an iodophenyl group.

[0084] Specific examples of the structural unit (1a) among the first structural units include structural units represented by the following formula. However, the first structural unit is not limited to the specific examples shown below. In the formula, R ３０ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0085] Specific examples of the structural unit (1b) include structural units represented by the following formulas:

[0086] Specific examples of the structural unit (1c) include structural units represented by the following formulas:

[0087] In the polymer (P), the content of the first structural unit is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more, based on the total amount of structural units contained in the polymer (P). Furthermore, the content of the first structural unit is preferably 65 mol% or less, more preferably 60 mol% or less, and even more preferably 55 mol% or less, based on the total amount of structural units contained in the polymer (P). By setting the content of the first structural unit within the above range, the difference in dissolution rate in a developer between an exposed portion and an unexposed portion can be appropriately increased while maintaining good sensitivity of the composition, thereby improving the CDU performance of the composition.

[0088] (Second structural unit) The second structural unit is a structural unit derived from a radiation-sensitive onium salt, and is typically a structural unit derived from a monomer comprising a radiation-sensitive onium cation and an organic anion. The second structural unit is thought to be formed by the radiation-sensitive onium cation being decomposed by the action of radiation to liberate an organic anion, which then bonds with hydrogen abstracted from components contained in the composition (e.g., a radiation-sensitive acid generator, an acid diffusion controller, a solvent, etc.), thereby generating an acid derived from the organic anion. Examples of the organic anion include a sulfonate anion and a carboxylate anion.

[0089] When the organic anion in the second structural unit is a sulfonate anion, the second structural unit is thought to function primarily as a radiation-sensitive acid generator by generating a strong acid that induces dissociation of the acid-dissociable group under normal conditions. On the other hand, when the organic anion in the second structural unit is a carboxylate anion, the second structural unit is thought to function primarily as an acid diffusion controller by generating a weak acid that does not induce dissociation of the acid-dissociable group under normal conditions. Here, "normal conditions" refers to conditions in which post-exposure baking (PEB) is performed at 110°C for 60 seconds.

[0090] The second structural unit is typically a structural unit derived from a monomer having a radiation-sensitive onium cation, an organic anion, and a group participating in polymerization. ３ － Ya-COO －) may be bonded to the main chain of the polymer via a linking group, and the radiation-sensitive onium cation may form a counter ion. Alternatively, the radiation-sensitive onium cation may be bonded to the main chain of the polymer via a linking group, and the organic anion may form a counter ion. In order to further improve the CDU performance of the present composition, it is preferable that the second structural unit be bonded to the main chain of the polymer via a linking group, and that the organic anion be a sulfonate anion (—SO ３ － ) is more preferably bonded to the main chain of the polymer via a linking group.

[0091] The radiation-sensitive cation in the second structural unit is preferably a sulfonium cation or an iodonium cation, more preferably a triarylsulfonium cation or a diaryliodonium cation, from the viewpoint of enhancing the sensitivity of the present composition. From the viewpoint of further enhancing the sensitivity of the present composition, the aromatic ring (i.e., S ＋ or I ＋ Preferably, at least one of an iodo group, a fluoro group, and a fluoroalkyl group is bonded to the aromatic ring bonded to the aromatic ring. The fluoroalkyl group is preferably a trifluoromethyl group.

[0092] It is preferable that at least a portion of the second structural units contained in the polymer (P) have an iodo group in the structural unit, since this can further increase the sensitivity while maintaining good CDU performance of the present composition. When the second structural unit has an iodo group, the iodo group is preferably bonded to an aromatic ring. Furthermore, when the second structural unit has an iodo group, the radiation-sensitive onium cation may have an iodo group, the organic anion may have an iodo group, or both the radiation-sensitive onium cation and the organic anion may have an iodo group.

[0093] The second structural unit may be a structural unit derived from a specific onium salt. In this case, the second structural unit preferably has an organic anion bonded to the main chain of the polymer via a linking group, and a specific cation forming a counter ion. Specific examples and preferred examples of the specific cation are as described above.

[0094] Specific examples of the second structural unit include structural units represented by the following formulas: However, the second structural unit is not limited to these specific examples. (In the formula, R ４０ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＋ is a radiation-sensitive onium cation. － is a sulfonate anion or a carboxylate anion.

[0095] In addition, Y in the above formula ＋ is a specific cation, the structural unit corresponds to a structural unit derived from a specific onium salt.

[0096] When the polymer (P) contains a second structural unit (i.e., when it is a polymer (P2)), the content of the second structural unit in the polymer (P) 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 contained in the polymer (P). Furthermore, the content of the second structural unit in the polymer (P) is preferably 25 mol% or less, more preferably 20 mol% or less, based on the total amount of structural units contained in the polymer (P). By setting the content of the second structural unit within the above range, the CDU performance of the present composition can be suitably improved.

[0097] Examples of the structural unit (other structural unit) that the polymer (P) may contain include the following third structural unit, fourth structural unit, fifth structural unit, and the like.

[0098] (Third structural unit) The polymer (P) may further contain a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring (referred to as the "third structural unit"). The polymer (P) having a hydroxyl group bonded to the aromatic ring is advantageous in that it can further improve the CDU performance of the composition, is highly effective in suppressing dissolution of unexposed areas into a developer, and can sufficiently reduce development defects. Furthermore, the polymer (P) containing the third structural unit can be preferably used in pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV. The third structural unit differs from the first structural unit in that it does not have an acid-dissociable group, and differs from the second structural unit in that it does not have an onium salt structure.

[0099] A preferred example of the third structural unit is a structural unit represented by the following formula (3). In formula (3), R ５０ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. １ represents a single bond, —COO—, or —CONH—. １ is an aromatic ring group. ４ is a substituent different from a hydroxyl group. n1 is an integer of 1 or more. n2 is an integer of 0 or more. When n2 is 2 or more, a plurality of R ４ are the same or different.)

[0100] In the above formula (3), R ５０ is preferably a hydrogen atom or a methyl group from the viewpoint of copolymerizability of the monomer that provides the third structural unit.

[0101] A １ The aromatic ring group represented by the formula (I) is a group obtained by removing (n1+n2+1) hydrogen atoms from the ring portion of a substituted or unsubstituted aromatic ring. The aromatic ring is preferably an aromatic hydrocarbon ring, for example, a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, etc. From the viewpoint of ease of synthesis of a monomer that provides a third structural unit and sensitivity, A １The aromatic ring constituting the aromatic ring group represented by the formula (I) is preferably a benzene ring or a naphthalene ring, more preferably a benzene ring. The position of the hydroxyl group bonded to the aromatic ring is also not particularly limited. For example, when the third structural unit has a hydroxyl group bonded to the benzene ring, the bonding position of the hydroxyl group on the benzene ring in the third structural unit may be any of the ortho-position, meta-position, and para-position relative to other groups.

[0102] R ４ R may be any group other than a hydroxyl group. ４ Specific examples of R in the above formula (1-ca) include １ａ , R ２ａ or R ３ａ Specific examples of the groups exemplified above include groups other than a hydroxyl group. n1 is preferably 1 to 3, and more preferably 1 or 2. n2 is preferably 0 to 5, and more preferably 0 to 2, and even more preferably 0 or 1.

[0103] Specific examples of the third structural unit include structural units represented by the following formulae: However, the third structural unit is not limited to these specific examples. (In the formula, R ５０ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group.

[0104] In the polymer (P), the content of the third structural unit is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 25 mol% or more, based on the total amount of structural units contained in the polymer (P). Furthermore, the content of the third structural unit is preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 60 mol% or less, based on the total amount of structural units contained in the polymer (P). By setting the content of the third structural unit within the above range, the CDU performance of the present composition can be made even better.

[0105] (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.

[0106] Specific examples of the fourth structural unit include structural units represented by the following formulas: However, the fourth structural unit is not limited to these specific examples. (In the formula, R Ｌ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0107] When the polymer (P) 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 (P), and the content of the fourth structural unit in the polymer (P) 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 (P).

[0108] (Fifth structural unit) The fifth structural unit may further include a structural unit having an alcoholic hydroxyl group (excluding the first to fourth structural units). By introducing the fifth structural unit into the polymer (P), 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.

[0109] 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 formulas. However, the fifth structural unit is not limited to these specific examples. (In the formula, R Ａ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0110] When the polymer (P) contains the fifth structural unit, from the viewpoint of enhancing the effect of suppressing development defects in the resist pattern, the content of the fifth structural unit is preferably 1 mol% or more, more preferably 3 mol% or more, based on the total amount of structural units contained in the polymer (P), 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 contained in the polymer (P).

[0111] In addition to the above, other structural units contained in the polymer (P) include, for example, 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); structural units containing a non-acid-dissociable hydrocarbon group (specifically, a structural unit derived from styrene or a halogenated styrene (for example, a styrene unit, a bromostyrene unit), 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 invention are not impaired.

[0112] From the viewpoint of obtaining a radiation-sensitive composition having excellent sensitivity, the polymer (P) preferably contains an iodine atom. When the polymer (P) contains an iodine atom, only one of the first to fifth structural units described above may contain an iodine atom, or two or more of them may contain an iodine atom. Furthermore, for example, when the first structural unit in the polymer (P) contains an iodine atom, some of the first structural units contained in the polymer (P) may contain an iodine atom, or all of the first structural units contained in the polymer (P) may contain an iodine atom.

[0113] Among these, it is preferable that at least one selected from the group consisting of the first structural unit and the second structural unit in the polymer (P) contains an iodine atom, since this can further increase the difference in solubility in a developer between an exposed portion and an unexposed portion. In order to fully obtain the effect of increasing the difference in solubility in a developer between an exposed portion and an unexposed portion, it is preferable that the polymer (P) contains an acid-dissociable group having an iodine atom. When the polymer (P) does not contain the second structural unit (i.e., when the present composition does not satisfy the first requirement), the presence of an iodine atom in the polymer (P) can further increase the sensitivity of the present composition.

[0114] The weight average molecular weight (Mw) of the polymer (P) 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 (P) 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 (P) within the above range, the coatability of the composition can be improved and development defects can be sufficiently suppressed, which is advantageous.

[0115] The ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the polymer (P) determined 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. The Mw / Mn of the polymer (P) is usually 1.0 or more.

[0116] The polymer (P) is preferably blended into the composition as at least a part of the base resin, and the content of the polymer (P) in the composition 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 composition.

[0117] The polymer (P) 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 radical initiators (e.g., azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile)), peroxide radical initiators (e.g., benzoyl peroxide), and the like. 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.

[0118] <Polymer (Q)> The polymer (Q) is preferably blended in the composition as a high-fluorine-containing polymer. The high-fluorine-containing polymer may be a polymer containing a structural unit having a fluorine atom (structural unit (f)) and a structural unit (s) (i.e., polymer (Q1)), or may be a polymer containing the structural unit (f) but not the structural unit (s) (i.e., polymer (Q2)).

[0119] When the high-fluorine content polymer is polymer (Q1), specific examples of the structural unit (s) include the same structural units as those exemplified in the description of the second structural unit that may be contained in polymer (P). In polymer (Q1), the content of structural unit (s) 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 contained in polymer (Q1). Furthermore, the content of structural unit (s) in polymer (Q1) is preferably 50 mol% or less, more preferably 40 mol% or less, based on the total amount of structural units contained in polymer (Q1).

[0120] The fluorine atom content of the high fluorine content polymer is not particularly limited as long as it is larger than that of the polymer (P). The fluorine atom content of the high fluorine content polymer 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 high fluorine content polymer 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 structural unit (f) contained in the high fluorine content polymer include the structural unit (f1) and the structural unit (f2) shown below. The high fluorine content polymer may have either the structural unit (f1) or the structural unit (f2) as the structural unit (f), or may have both the structural unit (f1) and the structural unit (f2).

[0122] Structural unit (f1) The structural unit (f1) is a structural unit represented by the following formula (9-1): The fluorine atom content of the high fluorine content polymer can be adjusted by adjusting the content ratio of the structural unit (f1) in the high fluorine content polymer. (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 C From the viewpoint of copolymerizability of the monomer that provides the structural unit (f1), 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 (f1), G is preferably a single bond or —COO—, and more preferably —COO—.

[0124] R ＥExamples 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 high-fluorine content polymer contains the structural unit (f1), the content of the structural unit (f1) is preferably 30 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more, based on the total amount of structural units contained in the high-fluorine content polymer. The content of the structural unit (f1) is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less, based on the total amount of structural units contained in the high-fluorine content polymer. By setting the content of the structural unit (f1) within the above range, the mass content of fluorine atoms in the high-fluorine content polymer 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 (f2) The structural unit (f2) is a structural unit represented by the following formula (9-2): When the high fluorine content polymer contains the structural unit (f2), the solubility of the high fluorine content polymer in an alkaline developer is improved, thereby further suppressing 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 ６０is 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 (f2) can be divided into a case where it has an alkali-soluble group and a case where it has a group that dissociates under the action of an alkali to increase its solubility in an alkaline developer (hereinafter simply referred to as an "alkali-dissociable group"). In this specification, "alkali-soluble" means that it is soluble in a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH) at 23°C. The "alkali-dissociable group" means a group that substitutes a hydrogen atom of an acid group such as a carboxy group or a hydroxyl group, and that is dissociated in a 2.38 mass% aqueous solution of TMAH at 23°C for 1 minute.

[0128] When the structural unit (f2) 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 (f2) has an alkali-soluble group, the affinity for an alkali developer can be increased, and development defects can be suppressed.

[0129] When the structural unit (f2) 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. When the structural unit (f2) has an alkali dissociable group, the surface of the resist film changes from hydrophobic to hydrophilic in the alkali development step. This can increase affinity to the developer and more efficiently suppress development defects. Examples of the structural unit (f2) 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 the high-fluorine content polymer contains the structural unit (f2), the content of the structural unit (f2) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more, based on the total amount of structural units contained in the high-fluorine content polymer. Furthermore, the content of the structural unit (f2) is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less, based on the total amount of structural units contained in the high-fluorine content polymer. By setting the content of the structural unit (f2) within the above range, the water repellency of the resist film can be further improved.

[0131] In addition to the structural unit (f1) and the structural unit (f2), the high fluorine content polymer may also contain a structural unit having an acid-dissociable group, a structural unit having a hydroxyl group bonded to an aromatic ring (this may also be referred to as a "structural unit (h)"), or a structural unit having an alicyclic hydrocarbon structure represented by the following formula (10) (this may also be referred to as a "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] When the high-fluorine content polymer contains the structural unit (g), the content of the structural unit (g) 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 contained in the high-fluorine content polymer. The content of the structural unit (g) is preferably 70 mol % or less, more preferably 60 mol % or less, and even more preferably 50 mol % or less, based on the total amount of structural units contained in the high-fluorine content polymer.

[0133] It is preferable that the high-fluorine content polymer contains the structural unit (h), since this can further improve the CDU performance of the composition and further reduce development defects. Specific examples of the structural unit (h) include the same structural units as those exemplified in the description of the third structural unit that the polymer (P) may contain. In the high-fluorine content polymer, the content of the structural unit (h) 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 contained in the high-fluorine content polymer. In addition, the content of the structural unit (h) in the high-fluorine content polymer is preferably 50 mol% or less, more preferably 40 mol% or less, based on the total amount of structural units contained in the high-fluorine content polymer.

[0134] The Mw of the high fluorine content polymer 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 high fluorine content polymer is preferably 50,000 or less, more preferably 30,000 or less, and even more preferably 20,000 or less. The polydispersity (Mw / Mn) of the high fluorine content polymer 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 present composition contains a high-fluorine polymer, the content of the high-fluorine polymer in the present composition is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of polymer (P). The content of the high-fluorine polymer is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, per 100 parts by mass of polymer (P).

[0136] <Radiation-Sensitive Onium Salt (C)> From the viewpoint of ensuring high sensitivity and excellent CDU performance, the present composition preferably contains a radiation-sensitive onium salt (C). The radiation-sensitive onium salt (C) contained in the present composition may be an onium salt composed of a specific cation and an organic anion (i.e., onium salt (C1)), or an onium salt composed of another cation and an organic anion (i.e., onium salt (C2)). The radiation-sensitive onium salt (C) may be an acid generator or an acid diffusion controller. When the radiation-sensitive onium salt (C) contains an acid generator, the acid generator contained in the present composition may be either the onium salt (C1) or the onium salt (C2). When the radiation-sensitive onium salt (C) contains an acid diffusion controller, the acid diffusion controller contained in the present composition may be either the onium salt (C1) or the onium salt (C2).

[0137] When the present composition satisfies the third requirement, the present composition may contain only one type of radiation-sensitive onium salt (C), or may contain two or more types. When the present composition contains two or more types of radiation-sensitive onium salts (C), that is, when the composition contains a first onium salt and a second onium salt different from the first onium salt as the radiation-sensitive onium salt (C), it is preferable that at least one of the first onium salt and the second onium salt has a specific cation. In other words, when the present composition satisfies the third requirement, it is preferable that the present composition contains an onium salt (C1) together with the polymer (P).

[0138] In one embodiment of the present composition containing a polymer (P) and an onium salt (C1), the first onium salt has a specific cation (i.e., the first onium salt is the onium salt (C1)) and generates an acid with a stronger acidity than the acid generated by the second onium salt. In another embodiment, the first onium salt has a specific cation and generates an acid with a weaker acidity than the acid generated by the second onium salt. In these embodiments, the second onium salt may or may not have a specific cation. The former embodiment corresponds to the present composition containing a non-polymeric acid generator and an acid diffusion controller, and at least the acid generator is the onium salt (C1). The latter embodiment corresponds to the present composition containing a non-polymeric acid generator and an acid diffusion controller, and at least the acid diffusion controller is the onium salt (C1).

[0139] In each of the above embodiments, from the viewpoint of sufficiently increasing the sensitivity of the present composition, the organic anion constituting the onium salt (C1) preferably has an iodine group. Furthermore, when the second onium salt does not have a specific cation, the second onium salt preferably has at least one group selected from the group consisting of an iodine group, a fluoro group, and a trifluoromethyl group (hereinafter also referred to as a "specific halogen group"). The specific halogen group may be contained in the radiation-sensitive cation constituting the second onium salt, in the organic anion, or in both. The specific halogen group is preferably bonded to an aromatic ring contained in the second onium salt.

[0140] Next, specific examples of the radiation-sensitive onium salt (C) will be described, divided into onium salt (C1) and onium salt (C2).

[0141] Onium Salt (C1) (Acid Generator) Specific examples of the specific cation contained in the acid generator (hereinafter also referred to as "specific acid generator") as the onium salt (C1) include those described above for the specific cation. The organic anion contained in the specific acid generator is not particularly limited. In terms of increasing the sensitivity of the present composition, a sulfonate anion, an imidate anion, or a methide anion is preferred. Specific examples of the sulfonate anion include anions represented by the following formula:

[0142]

[0143]

[0144] Specific examples of the specific acid generator include appropriate combinations of the radiation-sensitive cations exemplified as specific examples of the specific cations and the anions exemplified as specific examples of the organic anions constituting the specific acid generator.

[0145] (Acid Diffusion Controller) Specific examples of the specific cation contained in the acid diffusion controller as the onium salt (C1) (hereinafter also referred to as the "specific acid diffusion controller") include those described above for the specific cation. Examples of the organic anion contained in the specific acid diffusion controller include a carboxylate anion, a sulfonate anion, and a sulfonamide anion.

[0146] Examples of the organic anion contained in the specific acid diffusion controller include anions represented by the following formula:

[0147] Specific examples of the specific acid diffusion controller include appropriate combinations of the radiation-sensitive cations exemplified as specific examples of the specific cations and the anions exemplified as specific examples of the organic anions constituting the specific acid diffusion controller.

[0148] Onium Salt (C2) (Acid Generator) The acid generator as the onium salt (C2) (hereinafter also referred to as "other acid generator") is not particularly limited, and any known radiation-sensitive acid generator used in resist pattern formation can be used as appropriate. The other acid generator is preferably a compound that generates, under the above-mentioned normal conditions, an acid in the composition that is more acidic than the acid generated by the acid diffusion controller (preferably a strong acid such as a sulfonic acid, imidic acid, or methide acid), thereby inducing dissociation of the acid-dissociable group.

[0149] From the viewpoint of increasing the sensitivity of the present composition and forming a resist film with excellent lithography performance, the other acid generator preferably has a sulfonium cation or an iodonium cation as the radiation-sensitive onium cation, and more preferably has an arylsulfonium cation or an aryliodonium cation. Specific examples of the radiation-sensitive onium cation contained in the other acid generator include cations represented by the following formulas:

[0150]

[0151] Specific examples of the organic anion constituting the other acid generator include the same organic anions as those exemplified in the description of the specific acid generator. Specific examples of the other acid generator also include appropriate combinations of the above-mentioned radiation-sensitive cations with the organic anions exemplified in the description of the specific acid generator.

[0152] Acid Diffusion Controller The acid diffusion controller as the onium salt (C2) (hereinafter also referred to as "other acid diffusion controller") is not particularly limited, and any known photodegradable base used in resist pattern formation can be used as appropriate. The other acid diffusion controller is preferably an onium salt that generates a carboxylic acid, a sulfonic acid, or a sulfonamide upon exposure. Furthermore, in terms of being able to form a resist film with superior lithography performance, it is preferable to use an onium salt having a sulfonium cation or an iodonium cation as the other acid diffusion controller.

[0153] Specific examples of the radiation-sensitive onium cation contained in the other acid diffusion controller include the same onium cations as those exemplified as the radiation-sensitive onium cations that may be contained in the other acid generator. Specific examples of the organic anion constituting the other acid diffusion controller include the same organic anions exemplified in the description of the specific acid diffusion controller. Specific examples of the other acid diffusion controller include appropriate combinations of specific examples of the radiation-sensitive onium cations that may be contained in the other acid generator and the organic anions exemplified in the description of the specific acid diffusion controller.

[0154] When an acid generator is incorporated into the composition, the content of the acid generator is preferably 1 part by mass or more, more preferably 5 parts by mass or more, per 100 parts by mass of polymer (P), 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 development defects caused by the acid generator, the content of the acid generator is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, per 100 parts by mass of polymer (P).

[0155] When an acid diffusion controller is blended in 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 (P) from the viewpoint of sufficiently improving sensitivity and CDU performance. Furthermore, from the viewpoint of suppressing the occurrence of development defects due to the acid diffusion controller, the content of the acid diffusion controller is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, per 100 parts by mass of polymer (P).

[0156] When an acid diffusion controller is incorporated into the composition, the content of the acid diffusion controller in the composition is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more, based on the total amount of the acid generator, the monomer that provides the second structural unit in the polymer (P2), and the monomer that provides the structural unit (s) in the polymer (B1) contained in the composition. Furthermore, the content of the acid diffusion controller is preferably 80 mol% or less, more preferably 70 mol% or less, based on the total amount of the acid generator, the monomer that provides the second structural unit in the polymer (P2), and the monomer that provides the structural unit (s) in the polymer (B1) 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.

[0157] <Other Components> The present composition may further contain components (hereinafter also referred to as "other components") other than the polymer (P), the polymer (Q), and the radiation-sensitive onium salt (C). Examples of other components include the components shown below.

[0158] The solvent is preferably one that can dissolve or disperse the components to be blended in the composition, and an organic solvent is preferably used. Specific examples of the solvent include alcohols, ethers, ketones, amides, esters, and hydrocarbons.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] Other Optional Components The present composition may further contain other components (hereinafter also referred to as "other optional components") other than the solvent. 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.

[0164] <Method for producing radiation-sensitive composition> The present composition can be produced, for example, by mixing components such as the polymer (P) 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, it is possible to improve the coatability and form a good resist pattern shape, which is advantageous.

[0165] 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.

[0166] <<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 a "coating step"), a step of exposing the resist film obtained by the coating step (hereinafter also referred to as an "exposure step"), and a step of developing the resist film exposed by the exposure step (hereinafter also referred to as a "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 CDU, and good resolution. Each step will be described below.

[0167] [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 (also referred to as SB or pre-bake (PB)) 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.

[0168] [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.

[0169] 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, an acid diffusion controller, polymer (P2), or polymer (Q1)). 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.

[0170] [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.

[0171] 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.

[0172] 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).

[0173] <<Compound>> The present disclosure provides a compound represented by the following formula (1A), a compound represented by the following formula (1B), a compound represented by the following formula (1C), and a compound represented by the following formula (1D). These compounds (specific onium salts) are suitable as radiation-sensitive acid generators (acid generators, acid diffusion controllers) used in preparing radiation-sensitive compositions used in resist pattern formation, or as monomers constituting polymer components (particularly base resins) of radiation-sensitive compositions.

[0174] (In formula (1A), R １ａ and R ２ａ is R １ａ is "-X １ -O-CR １１ R １２ -X ２ -R １３ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R ２ａ and (a3) ​​R ３ａ At least one of X is an iodo group. １ is a single bond or a divalent linking group. １１ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. １２ and R １３ is R １２is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R １３ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R １２ and R １３ are combined together to form R １２ and the carbon atom to which R １３ X to which ２ represents a ring structure formed together with X ２ is an oxygen atom or a sulfur atom. a4 is an integer of 1 to 5, and satisfies (a1+a4)≦5. r is 0 or 1. M － is a monovalent anion. １ａ , multiple R ２ａ , multiple R ３ａ , multiple "-X １ -O-CR １１ R １２ -X ２ -R １３ " are the same or different.)

[0175] (In formula (1B), R １ａ and R ２ａ is R １ａ is "-X １ -COO-CR １４ R １５ R １６ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R ２ａ and (a3) ​​R ３ａ At least one of X is an iodo group. １ is a single bond or a divalent linking group. １４ R is a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aliphatic heterocyclic group. １５ and R １６are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic heterocyclic group, or R １５ and R １６ are aligned with each other and R １５ and R １６ represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which R is bonded. １４ When is a hydrogen atom, R １５ and R １６ or both of which are, independently of each other, a substituted or unsubstituted monovalent alicyclic unsaturated hydrocarbon group, a substituted or unsubstituted monovalent aromatic hydrocarbon group, or a monovalent aromatic heterocyclic group, or R １５ and R １６ are aligned with each other and R １５ and R １６ represents an alicyclic unsaturated hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which a is bonded. a4 is an integer of 1 to 5, and satisfies (a1+a4)≦5. r is 0 or 1. M － is a monovalent anion having an iodine group. １ａ , multiple R ２ａ , multiple R ３ａ , multiple "-X １ -COO-CR １４ R １５ R １６ " are the same or different.)

[0176] (In formula (1C), R １ａ and R ２ａ is R １ａ is "-X １ -NR １７ -CO-R １８ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R１ａ , (a2) R ２ａ and (a3) ​​R ３ａ At least one of X is an iodo group. １ is a single bond or a divalent linking group. １7 R is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １８ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. a4 is an integer of 1 to 5 and satisfies (a1+a4)≦5. r is 0 or 1. M － is a monovalent anion having an iodine group. １ａ , multiple R ２ａ , multiple R ３ａ , multiple "-X １ -NR １７ -CO-R １８ " are the same or different.)

[0177] (In formula (1D), R １ａ and R ２ａ is R １ａ is "-X １ -NR １９ -SO ２ -R ２０ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R ２ａ and (a3) ​​R ３ａ At least one of X is a monovalent group having a halogen atom. １ is a single bond or a divalent linking group. １９ R is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ２０is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. a4 is an integer of 1 to 5 and satisfies (a1+a4)≦5. r is 0 or 1. M － is a monovalent anion having an iodine group. １ａ , multiple R ２a , multiple R ３ａ , multiple "-X １ -NR １９ -SO ２ -R ２０ " are the same or different.)

[0178] In the above formula (1A), R １ａ , R ２ａ , R ３ａ , X １ , R １１ , R １２ , R １３ , a1, a2, a3, a4 and r are R in the above formula (1-ca), respectively. １ａ , R ２ａ , R ３ａ , X １ , R １４ , R １５ , R １６ , a1, a2, a3, a4 and r. － Specific examples of M include the same organic anions as those exemplified in the description of the specific acid generator and the specific acid diffusion controller. － may be an organic anion constituting a monomer that provides the second structural unit in the polymer (P).

[0179] In the above formula (1B), formula (1C) and formula (1D), R １ａ , R ２ａ , R ３ａ , X １ , R １４ , R １５ , R １６ , a1, a2, a3, a4 and r are R in the above formula (1-ca), respectively. １ａ , R ２ａ , R ３ａ , X １ , R １４ , R １５ , R １６ , a1, a2, a3, a4 and r.－ Specific examples of M include the same organic anions having an iodine group as those exemplified in the description of the specific acid generator and the specific acid diffusion controller. － may be an organic anion constituting a monomer that provides the second structural unit in the polymer (P) that has an iodine group.

[0180] The compound represented by the formula (1A), the compound represented by the formula (1B), the compound represented by the formula (1C), and the compound represented by the formula (1D) can be synthesized by appropriately combining standard methods in organic chemistry. As an example of a method for synthesizing the compound represented by the formula (1A), first, １ -O-CR １１ R １２ -X ２ -R １３ " is a hydroxyl group, and then the sulfonium halide is reacted with "-CR １１ R １２ -X ２ -R １３ " to protect the hydroxyl group to obtain an intermediate product, and then reacting the obtained intermediate product with a halide having a structure corresponding to M － The compound represented by the above formula (1A) can be obtained by reacting the compound represented by the above formula (1A) with a compound comprising an anion and a cation (for example, an ammonium cation) which gives the compound represented by the above formula (1A).

[0181] In addition, the compounds represented by the above formula (1B), formula (1C) or formula (1D) can also be obtained in the same manner. For example, in the above formula (1B), "-X １ -COO-CR １４ R １５ R １６ " is a carboxy group, and then the sulfonium halide is reacted with "-CR １４ R １５ R １６ " to protect the carboxy group to obtain an intermediate product, and then reacting the resulting intermediate product with M －The compound represented by formula (1B) can be obtained by reacting a compound represented by formula (1A), a compound represented by formula (1B), a compound represented by formula (1C), and a compound represented by formula (1D) with a compound consisting of an anion and a cation that give the compound represented by formula (1B). However, the synthesis methods of the compound represented by formula (1A), the compound represented by formula (1B), the compound represented by formula (1C), and the compound represented by formula (1D) are not limited to those described above.

[0182] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the following examples, "parts" and "%" are by mass unless otherwise specified.

[0183] 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.

[0184] <Synthesis of Compounds> [Synthesis Example 1-1] (Synthesis of Photoacid Generator (A-16)) Compound (A-16) was synthesized according to the following scheme.

[0185] To methylene chloride (40 mL) were added (A-16-A) (10.0 g) and phenol (6.0 g). The resulting mixture was cooled to -40°C, and then trifluoromethanesulfonic anhydride (4.4 mL) was added, followed by stirring at room temperature for 7 hours. Methylene chloride was added to the resulting mixture, and the organic layer was washed with water, and the solvent was distilled off. After drying over sodium sulfate, the solvent was distilled off, and the resulting mixture was purified by column chromatography to obtain (A-16-B) in a good yield. Subsequently, 3.0 g of (A-16-B) was dissolved in methylene chloride, passed through an ion exchange resin, and then the solvent was distilled off, yielding (A-16-C) in a good yield.

[0186] Methylene chloride (30 mL), potassium carbonate (11.3 g), and chloromethyl methyl ether (1.3 g) were added to 4.7 g of (A-16-C), and the mixture was stirred at room temperature for 2 hours. After dilution with water, the mixture was extracted with methylene chloride. After drying with sodium sulfate, the solvent was distilled off, and the mixture was purified by column chromatography to obtain (A-16-D) in good yield.

[0187] Methylene chloride (20 mL), water (20 mL), and (A-16-1) (6.5 g) were added to (A-16-D) (4.9 g), and the mixture was stirred at room temperature for 2 hours. Thereafter, water was added for dilution, and methylene chloride was added for extraction, and the organic layer was separated. The obtained organic layer was washed with water and dried over sodium sulfate, after which the solvent was distilled off and the mixture was purified by column chromatography to obtain photoacid generator (A-16) in good yield.

[0188] Synthesis Example 1-2 (Synthesis of Photoacid Generator (A-39)) Compound (A-39) was synthesized according to the following scheme.

[0189] To methylene chloride (22 mL) were added (A-39-A) (5.0 g) and methyl 2-methoxybenzoate (3.7 g). The resulting mixture was cooled to -40°C, and then trifluoromethanesulfonic anhydride (2.2 mL) was added, followed by stirring at room temperature for 7 hours. Methylene chloride was added to the resulting mixture, and the organic layer was washed with water, and the solvent was evaporated. After drying over sodium sulfate, the solvent was evaporated, and the residue was purified by column chromatography to obtain (A-39-B) in a good yield.

[0190] Tetrahydrofuran (40 mL), water (40 mL), and lithium hydroxide monohydrate (550 mg) were added to 5.8 g of (A-39-B), and the mixture was stirred at room temperature for 2 hours. Thereafter, a saturated aqueous solution of ammonium chloride was added to terminate the reaction, and then methylene chloride was added for extraction. After drying with sodium sulfate, the solvent was distilled off, and the mixture was purified by column chromatography to obtain (A-39-C) in good yield.

[0191] Methylene chloride (10 mL), di-tert-butyl dicarbonate (6.0 g), 4-dimethylaminopyridine (1.7 g), triethylamine (1.4 g), and 2-methylpropan-2-ol (10 g) were added to 5.2 g of (A-39-C), and the mixture was stirred at room temperature for 2 hours. Subsequently, a saturated aqueous ammonium chloride solution was added to terminate the reaction, and then methylene chloride was added for extraction. After drying over sodium sulfate, the solvent was distilled off, and the mixture was purified by column chromatography to obtain (A-39-D) in good yield. Subsequently, 4.6 g of (A-39-D) was dissolved in methylene chloride, passed through an ion exchange resin, and the solvent was distilled off to obtain (A-39-E) in good yield.

[0192] Methylene chloride (30 mL), water (20 mL), and (A-39-1) (5.4 g) were added to (A-39-E) (4.0 g), and the mixture was stirred at room temperature for 2 hours. After dilution with water, the mixture was extracted with methylene chloride and the organic layer was separated. The resulting organic layer was washed with water and dried over sodium sulfate. The solvent was then removed by distillation, and the mixture was purified by column chromatography to obtain photoacid generator (A-39) in good yield.

[0193] With reference to the synthesis methods of Synthesis Examples 1-1 and 1-2, the following photoacid generators (A-1) to (A-15), (A-17) to (A-38), and (A-40) to (A-42) were synthesized.

[0194]

[0195]

[0196] <Synthesis of Polymer> For the synthesis of the polymer [P] and the additive [Q], compounds represented by the following formulae (M-1) to (M-36) were used, and polymerization was carried out by the method shown below.

[0197]

[0198] [Synthesis Examples 2-1 to 2-54] Synthesis of polymers (P-1) to (P-54) Each monomer was combined and copolymerized in tetrahydrofuran (THF) solvent. The resulting mixture was crystallized in methanol and repeatedly washed with hexane. After isolation and drying, polymers (P-1) to (P-54) having the compositions shown in Tables 1 and 2 were obtained as [P] polymers. The compositions of the resulting polymers were: １ The Mw and dispersity (Mw / Mn) were confirmed by H-NMR under the GPC conditions described above. The Mw and Mw / Mn values ​​are shown in Tables 1 and 2, along with the type, amount used, and content of each monomer. In Tables 1 and 2, the "amount used (mol %)" is the value when the total number of moles of the monomers used in the polymerization is taken as 100 mol %, and the "content (mol %)" is the value when the total number of moles of the monomers constituting the polymer is taken as 100 mol % (the same applies to Table 3).

[0199]

[0200]

[0201] <Synthesis of [Q] Polymer (High Fluorine Content Polymer)> [Synthesis Examples 2-55 to 2-57] Synthesis of Polymers (Q-1) to (Q-3) Each monomer was combined and copolymerized in tetrahydrofuran (THF) solvent. The resulting product was crystallized in methanol and repeatedly washed with hexane. After isolation and drying, polymers (Q-1) to (Q-3) with the compositions shown in Table 3 were obtained. The resulting polymers had the following compositions: １ The Mw and dispersity (Mw / Mn) were confirmed by H-NMR under the GPC conditions described above. The Mw and Mw / Mn values ​​are shown in Table 3 together with the type, amount used, and content of each monomer.

[0202]

[0203] <Preparation of Radiation-Sensitive Composition> The acid generator (A), acid diffusion controller (D), and solvent (E) used in the preparation of the radiation-sensitive composition are shown below.

[0204] [A] Acid Generator The compounds represented by the above formulas (A-1) to (A-42) and the compounds represented by the following formulas (Ac-1) to (Ac-7) were used as acid generators.

[0205] [D] Acid Diffusion Controller Compounds represented by the following formulae (D-1) to (D-12) were used as acid diffusion controllers.

[0206] [E] Solvent The following organic solvents were used as the [E] solvent: (E-1): Propylene glycol monomethyl ether acetate (E-2): Propylene glycol monomethyl ether

[0207] [Example 1] Preparation of Radiation-Sensitive Composition (R-1) 100 parts by mass of (P-1) as a [P] polymer, 45 parts by mass of (A-16) as an [A] acid generator, 35 mol% of (D-1) as an [D] acid diffusion controller based on the total anion of (A-16), 5,500 parts by mass of (E-1) and 1,500 parts by mass of (E-2) as [E] solvents were mixed. The resulting mixture was filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive composition (R-1).

[0208] [Examples 2 to 116 and Comparative Examples 1 to 7] Preparation of Radiation-Sensitive Compositions (R-2) to (R-116) and (CR-1) to (CR-7) Radiation-sensitive compositions (R-2) to (R-116) and (CR-1) to (CR-7) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Tables 4, 5, and 6 were used. In Tables 4, 5, and 6, "parts by mass" represents a value relative to 100 parts by mass of the polymer [P] used in preparing the radiation-sensitive composition. The content of the acid diffusion controller [D] represents the proportion (mol %) to the sum of the amount of anion in the acid generator [A] and the amount of anion in the monomer that provides the second structural unit in the polymer [P].

[0209]

[0210]

[0211]

[0212] <Formation of Resist Pattern> Each of the radiation-sensitive compositions prepared above 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.). After soft baking (SB) at 100°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a 45-nm-thick resist film. Next, this resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3400," ASML, NA=0.33, illumination conditions: Conventional s=0.89). The resist film was then subjected to PEB (post-exposure bake) at 110°C for 60 seconds. Next, development was carried out using a 2.38 wt % aqueous solution of TMAH at 23° C. for 30 seconds to form a positive-type 48 nm pitch, 24 nm contact hole pattern.

[0213] <Evaluation> The sensitivity and number of development defects of each radiation-sensitive composition were evaluated by measuring each resist pattern formed as described above according to the methods described below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist pattern. The evaluation results are shown in Tables 7 and 8.

[0214] [Sensitivity] In forming the resist pattern, the exposure dose for forming a 24 nm contact hole pattern was defined as the optimum exposure dose, and this optimum exposure dose was used as the sensitivity (mJ / cm ２ The smaller the sensitivity, the better the result. ２ "A" (very good) if less than 35 mJ / cm ２ More than 40mJ / cm ２ "B" (good) if less than 40 mJ / cm ２ 45mJ / cm or more ２ "C" (fairly good) if less than 45 mJ / cm ２ In the above cases, the product was judged as "D" (poor).

[0215] [Number of Development Defects] A resist film was exposed to an optimum exposure dose to form a 24 nm contact hole pattern, which was used as a wafer for defect inspection. The number of defects on this wafer for defect inspection was measured using a defect inspection device (KLA-Tencor's "KLA2810"). The defects measured above were then classified into those determined to be originating from the resist film and those due to foreign matter of external origin, and the number of defects determined to be originating from the resist film was calculated. Regarding the number of development defects, if the number of defects determined to be originating from the resist film was less than 15, it was evaluated as "A" (very good); if it was 15 or more but less than 30, it was evaluated as "B" (good); if it was 30 or more but less than 45, it was evaluated as "C" (fairly good); and if it was 45 or more, it was evaluated as "D" (poor).

[0216]

[0217]

[0218] As is clear from the results in Tables 7 and 8, the radiation-sensitive compositions of Examples 1 to 116 had high sensitivity and a small number of development defects. In contrast, the radiation-sensitive compositions of Comparative Examples 1 to 7 were rated "D" in either the sensitivity or the number of development defects, and were inferior to Examples 1 to 116.

[0219] The radiation-sensitive composition and method for forming a resist pattern according to the present disclosure can reduce the number of development defects while achieving high sensitivity, and therefore can be suitably used for forming fine resist patterns in lithography processes for various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. A radiation-sensitive composition comprising a polymer (P) containing a structural unit having an acid-dissociable group, and satisfying one or more of the following first, second and third requirements: first requirement: the polymer (P) further contains a structural unit derived from a radiation-sensitive onium salt; second requirement: the composition further contains a polymer (Q1) that is a different polymer from the polymer (P) and contains a structural unit derived from a radiation-sensitive onium salt; and third requirement: the composition further contains a non-polymeric radiation-sensitive onium salt (C), wherein at least one selected from the group consisting of the structural unit derived from a radiation-sensitive onium salt in the polymer (P), the structural unit derived from a radiation-sensitive onium salt in the polymer (Q1), and the radiation-sensitive onium salt (C) contains a specific cation having an iodine group and at least one group selected from the group consisting of an acid-dissociable group, an amide group, and a sulfonamide group.

2. The radiation-sensitive composition according to claim 1, which satisfies the third requirement, and wherein the radiation-sensitive onium salt (C) includes an onium salt (C1) composed of the specific cation and an organic anion.

3. The radiation-sensitive composition according to claim 2, wherein the organic anion in the onium salt (C1) has an iodine group.

4. The radiation-sensitive composition according to claim 2, wherein the radiation-sensitive onium salt (C) comprises a first onium salt and a second onium salt different from the first onium salt, and at least one of the first onium salt and the second onium salt has the specific cation.

5. The radiation-sensitive composition according to claim 4, wherein the first onium salt has the specific cation and generates an acid stronger in acidity than the acid generated by the second onium salt.

6. The radiation-sensitive composition according to claim 4, wherein the first onium salt has the specific cation and generates an acid weaker in acidity than the acid generated by the second onium salt.

7. The radiation-sensitive composition according to claim 4, wherein the first onium salt has the specific cation, and the second onium salt does not have the specific cation but has at least one group selected from the group consisting of an iodo group, a fluoro group, and a trifluoromethyl group.

8. The radiation-sensitive composition according to claim 1, wherein the specific cation is represented by the following formula (1-ca): (In formula (1-ca), R １ａ and R ２ａ is R １ａ is "-X １ -R ４ａ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R ２ａ and (a3) ​​R ３ａ At least one of R is an iodo group. ４ａ is a group represented by the following formula (2-1), formula (2-2), formula (2-3) or formula (2-4). １ is a single bond or a divalent linking group. a4 is an integer of 1 to 5, and satisfies (a1+a4)≦5. r is 0 or 1. In the formula, multiple R １ａ , multiple R ２ａ , multiple R ３ａ , multiple "-X １ -R ４ａ " are the same or different.) (In formula (2-1), R １１ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. １２ and R １３ is R １２ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R １３ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R １２ and R １３ are combined together to form R １２ and the carbon atom to which R １３ X to which ２ represents a ring structure formed together with X ２ is an oxygen atom or a sulfur atom. "*" represents a bond. In formula (2-2), R １４ R is a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aliphatic heterocyclic group. １５ and R １６ are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic heterocyclic group, or R １５ and R １６ are aligned with each other and R １５ and R １６ represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which R is bonded. １４ When is a hydrogen atom, R １５ and R １６ or both of which are, independently of each other, a substituted or unsubstituted monovalent alicyclic unsaturated hydrocarbon group, a substituted or unsubstituted monovalent aromatic hydrocarbon group, or a monovalent aromatic heterocyclic group, or R １５ and R １６ are aligned with each other and R １５ and R １６ represents an alicyclic unsaturated hydrocarbon structure having 3 to 20 carbon atoms formed together with the carbon atom to which it is bonded. "*" represents a bond. In formula (2-3), R １7 is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １8 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. "*" represents a bond. In formula (2-4), R １９ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ２０ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. "*" represents a bond.

9. The radiation-sensitive composition according to claim 1, which does not satisfy the first requirement and wherein the polymer (P) contains an iodine atom.

10. The radiation-sensitive composition according to claim 1, wherein at least one selected from the group consisting of the polymer (P) and the polymer (Q1) contains a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring.

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

12. The method for forming a resist pattern according to claim 11, wherein the resist film is exposed using extreme ultraviolet light.

13. A compound represented by the following formula (1A): (In formula (1A), R １ａ and R ２ａ is R １ａ is "-X １ -O-CR １１ R １２ -X ２ -R １３ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R ２ａ and (a3) ​​R ３ａ At least one of X is an iodo group. １ is a single bond or a divalent linking group. １１ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. １２ and R １３ is R １２ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R １３ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R １２ and R １３ are combined together to form R １２ and the carbon atom to which R １３ X to which ２ represents a ring structure formed together with X ２ is an oxygen atom or a sulfur atom. a4 is an integer of 1 to 5, and satisfies (a1+a4)≦5. r is 0 or 1. M － is a monovalent anion. １ａ , multiple R ２ａ , multiple R ３ａ , multiple "-X １ -O-CR １１ R １２ -X ２ -R １３ " are the same or different.) 14. A compound represented by the following formula (1B): (In formula (1B), R １ａ and R ２ａ is R １ａ is "-X １ -COO-CR １４ R １５ R １６ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R ２ａ and (a3) ​​R ３ａ At least one of X is an iodo group. １ is a single bond or a divalent linking group. １４ R is a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aliphatic heterocyclic group. １５ and R １６ are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic heterocyclic group, or R １５ and R １６ are aligned with each other and R １５ and R １６ represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which R is bonded. １４ When is a hydrogen atom, R １５ and R １６ or both of which are, independently of each other, a substituted or unsubstituted monovalent alicyclic unsaturated hydrocarbon group, a substituted or unsubstituted monovalent aromatic hydrocarbon group, or a monovalent aromatic heterocyclic group, or R １５ and R １６ are aligned with each other and R １５ and R １６ represents an alicyclic unsaturated hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which a is bonded. a4 is an integer of 1 to 5, and satisfies (a1+a4)≦5. r is 0 or 1. M － is a monovalent anion having an iodine group. １ａ , multiple R ２ａ , multiple R ３ａ , multiple "-X １ -COO-CR １４ R １５ R １６ " are the same or different.) 15. A compound represented by the following formula (1C): (In formula (1C), R １ａ and R ２ａ is R １ａ is "-X １ -NR １７ -CO-R １８ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R ２ａ and (a3) ​​R ３ａ At least one of X is an iodo group. １ is a single bond or a divalent linking group. １7 R is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １８ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. a4 is an integer of 1 to 5 and satisfies (a1+a4)≦5. r is 0 or 1. M － is a monovalent anion having an iodine group. １ａ , multiple R ２ａ , multiple R ３ａ , multiple "-X １ -NR １７ -CO-R １８ " are the same or different.) 16. A compound represented by the following formula (1D): (In formula (1D), R １ａ and R ２ａ is R １ａ is "-X １ -NR １９ -SO ２ -R ２０ " is a substituent different from R ２ａ is a 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 substituent. a1 is an integer of 0 to 4, a2 is an integer of 0 to 5, and a3 is an integer of 0 to (2r+5). However, (a1+a2+a3)≧1 is satisfied, and (a1) R １ａ , (a2) R ２ａ and (a3) ​​R ３ａ At least one of X is a monovalent group having a halogen atom. １ is a single bond or a divalent linking group. １９ R is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ２０ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. a4 is an integer of 1 to 5 and satisfies (a1+a4)≦5. r is 0 or 1. M － is a monovalent anion having an iodine group. １ａ , multiple R ２a , multiple R ３ａ , multiple "-X １ -NR １９ -SO ２ -R ２０ " are the same or different.)

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