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

Abstract

This radiation-sensitive composition contains a polymer the solubility of which in a developing solution changes by the action of acid, wherein the polymer and / or a component other than the polymer has a partial structure represented by formula (1).

Description

Radiation-sensitive compositions, methods for forming resist patterns, compounds, polymers and monomers

[0001] The present invention relates to radiation-sensitive compositions, methods for forming resist patterns, compounds, polymers, and monomers.

[0002] Radiation-sensitive compositions used in microfabrication by lithography generate acid in the exposed areas when irradiated with radiation such as far-ultraviolet light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electromagnetic waves such as extreme ultraviolet light (EUV, wavelength 13.5 nm), and charged particle beams such as electron beams. A chemical reaction starting from this acid creates a difference in the dissolution rate in the developer between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

[0003] Radiation-sensitive compositions are required to have good sensitivity to radiation such as extreme ultraviolet light and electron beams, as well as good Critical Dimension Uniformity (CDU) and few development defects.

[0004] In response to these requirements, the types and molecular structures of polymers, acid generators, and other components used in radiation-sensitive compositions have been investigated, and their combinations have also been studied in detail (see Japanese Patent Publication Nos. 2010-134279, 2014-224984, 2016-047815, and 2021-009357).

[0005] Japanese Patent Publication No. 2010-134279, Japanese Patent Publication No. 2014-224984, Japanese Patent Publication No. 2016-047815, Japanese Patent Publication No. 2021-009357

[0006] As resist patterns become even more miniaturized, the required performance levels are increasing, and there is a need for radiation-sensitive compositions that can meet these requirements.

[0007] The present invention has been made based on the above circumstances, and an object thereof is to provide a radiation-sensitive composition and a resist pattern forming method that have good sensitivity and CDU and few development defects. Another object of the present invention is to provide a compound suitable as an acid diffusion control agent contained in the radiation-sensitive composition. Another object of the present invention is to provide a polymer and a monomer thereof suitable as a polymer contained in the radiation-sensitive composition.

[0008] The invention made to solve the above problems contains a polymer whose solubility in a developer changes by the action of an acid, and the polymer or a component other than the polymer or both have a partial structure represented by the following formula (1): radiation-sensitive composition. (In formula (1), M ＋ is S ＋ or I ＋ . n is an integer of 1 or more and m or less. When M ＋ is S ＋ , m is 3, and when M ＋ is I ＋ , m is 2. Ar １ is a group obtained by removing (a + 1) hydrogen atoms from a substituted or unsubstituted aromatic ring. When n is 2 or 3, a plurality of Ar １ are the same or different. a is an integer of 1 to 5. R １ is a substituted or unsubstituted hydrocarbon group. When m - n is 2, two R １ are the same or different. *1 indicates a bonding site.)

[0009] Another invention made to solve the above problems is a resist pattern forming method including a step of coating the above-described radiation-sensitive composition directly or indirectly on a substrate, a step of exposing a resist film formed by the coating, and a step of developing the exposed resist film.

[0010] Still another invention made to solve the above problems is a compound represented by the following formula (1-1). (In formula (1-1), M ＋ is S ＋ or I ＋ . n is an integer of 1 or more and m or less. M＋ S ＋ In that case, m is 3, and M ＋ I ＋ In that case, m is 2. １ This is a group obtained by removing (a+1) hydrogen atoms from a substituted or unsubstituted aromatic ring. When n is 2 or 3, multiple Ar １ They are either the same or different. a is an integer between 1 and 5. R １ is a substituted or unsubstituted hydrocarbon group. When m-n is 2, there are two R １ They are either the same or different. － (This is a carboxylic acid anion.)

[0011] Another invention made to solve the above problems is a polymer having a structural unit represented by the following formula (IV-1) or (IV-2). (In formulas (IV-1) and (IV-2), R ５ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ The bond is a single bond or an *-COO- bond. * is R ５ This shows the bonding site with the carbon atom to which it is bonded. A ＋ represents the cation portion in formula (1) above. In formula (IV-1), Ar ３ R is a group obtained by removing two hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 20 members. In formula (IV-2), R ６ and R ７ Each of these is independently a hydrogen atom, a fluoro group, a C1-C10 alkyl group, or a C1-C10 monovalent fluorinated alkyl group. １ n is an integer between 1 and 10. １ If there are two or more, multiple R ６ They are either identical or different from each other, and multiple R ７ They are either identical or different from each other. ８ and R ９ Each of these is independently a fluoro group or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. ２ n is an integer between 1 and 10. ２ If there are two or more, multiple R ８ They are either identical or different from each other, and multiple R ９They are either identical or different from one another.

[0012] Another invention made to solve the above problems is a monomer represented by the following formula (iv-1) or (iv-2). (In equations (iv-1) and (iv-2), R ５ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ The bond is a single bond or an *-COO- bond. * is R ５ This shows the bonding site with the carbon atom to which it is bonded. A ＋ represents the cation portion in formula (1) above. In formula (iv-1), Ar ３ R is a group obtained by removing two hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring with 6 to 20 members. In formula (iv-2), R ６ and R ７ Each of these is independently a hydrogen atom, a fluoro group, a C1-C10 alkyl group, or a C1-C10 monovalent fluorinated alkyl group. １ n is an integer between 1 and 10. １ If there are two or more, multiple R ６ They are either identical or different from each other, and multiple R ７ They are either identical or different from each other. ８ and R ９ Each of these is independently a fluoro group or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. ２ n is an integer between 1 and 10. ２ If there are two or more, multiple R ８ They are either identical or different from each other, and multiple R ９ They are either identical or different from one another.

[0013] According to the radiation-sensitive composition and resist pattern formation method of the present invention, it is possible to form a resist pattern with good sensitivity and CDU, and with few development defects. The compounds of the present invention are suitable as acid diffusion control agents contained in the radiation-sensitive composition. The polymers of the present invention are suitable as polymers contained in the radiation-sensitive composition. The monomers of the present invention are suitable as monomers for synthesizing the polymers of the present invention. Therefore, these can be suitably used in semiconductor device processing processes and the like, where further miniaturization is expected in the future.

[0014] The radiation-sensitive composition, resist pattern formation method, compound, polymer, and monomer of the present invention will be described in detail below.

[0015] In this specification, unless otherwise specified, the upper and lower limits of numerical ranges may be expressed as "less than or equal to" or "less than," and the lower limit may be expressed as "greater than or equal to" or "greater than." Furthermore, the upper and lower limits may be any combination of the disclosed numerical values. When a numerical range is indicated using the symbol "~," it means that the numerical range includes the values ​​of both the upper and lower limits. For example, "1 to 20 carbon atoms" means "1 carbon atom or more and 20 carbon atoms or less."

[0016] <Radiation-sensitive composition> The radiation-sensitive composition contains a polymer whose solubility in a developer changes upon the action of an acid (hereinafter also referred to as "[A] polymer"), and the [A] polymer, a component other than the [A] polymer, or both thereof have a substructure represented by formula (1) described later (hereinafter also referred to as "substructure (x)").

[0017] The radiation-sensitive composition, by having the above configuration, exhibits good sensitivity and CDU, and has fewer development defects. The reason for this is not entirely clear, but it can be inferred, for example, as follows: The cation portion in substructure (x) contains an aromatic ring having a cyano group as a substituent. It is thought that introducing a cyano group to the aromatic ring improves the radiation absorption efficiency and improves solubility in the developer, resulting in the above effects.

[0018] The radiation-sensitive composition typically contains an organic solvent (hereinafter also referred to as "[D] organic solvent"). The radiation-sensitive composition may also contain a radiation-sensitive acid generator. Examples of the radiation-sensitive acid generator include the [A] polymer itself if the [A] polymer has a structural unit containing a group that generates sulfonic acid upon exposure to radiation, and other components include a radiation-sensitive acid generator (hereinafter also referred to as "[B] acid generator"). The radiation-sensitive composition may also contain an acid diffusion control agent. Examples of the acid diffusion control agent include the [A] polymer itself if the [A] polymer has a structural unit containing a substructure (x), and other components include an acid diffusion control agent as a compound having a substructure (x) (hereinafter also referred to as "[C] acid diffusion control agent"). The radiation-sensitive composition may contain other optional components as long as they do not impair the effects of the present invention.

[0019] The radiation-sensitive composition can be prepared, for example, by mixing [A] a polymer and, if necessary, [B] an acid generator, [C] an acid diffusion control agent, [D] an organic solvent, and other optional components in predetermined proportions, and filtering the resulting mixture through a membrane filter with a pore size of 0.2 μm or less.

[0020] [Substructure (x)] Substructure (x) is a substructure contained in the [A] polymer, a component other than the [A] polymer, or both. In other words, substructure (x) is contained in any of the components contained in the radiation-sensitive composition. The component other than the [A] polymer is not particularly limited as long as it is a component contained in the radiation-sensitive composition. A [C] acid diffusion control agent is preferred as the component other than the [A] polymer. In other words, it is preferable that the radiation-sensitive composition contains substructure (x) in the [A] polymer, the [C] acid diffusion control agent, or both. Substructure (x) may be contained in one or more components. The radiation-sensitive composition may contain one or more substructures (x).

[0021] Substructure (x) is a substructure represented by the following equation (1). Hereafter, in the following equation (1), M ＋ - (Ar１ - (CN) ａ ) ｎ (R １ ) ｍ－ｎ The part represented by *1-COO is called the "cation part," and － The part represented by this is called the "anion part".

[0022]

[0023] In the above formula (1), M ＋ is, S ＋ Or I ＋ n is an integer between 1 and m, inclusive. ＋ S ＋ In that case, m is 3, and M ＋ I ＋ In that case, m is 2. １ This is a group obtained by removing (a+1) hydrogen atoms from a substituted or unsubstituted aromatic ring. When n is 2 or 3, multiple Ar １ They are either the same or different. a is an integer between 1 and 5. R １ is a substituted or unsubstituted hydrocarbon group. When m-n is 2, there are two R １ These are either the same or different. *1 indicates the bonding site.

[0024] M ＋ S ＋ In this case, that is, when the cation is a sulfonium cation, m is 3. ＋ I ＋ In this case, that is, when the cation is an iodonium cation, m is 2.

[0025] The term "aromatic ring" includes "aromatic hydrocarbon rings" and "aromatic heterocycles." Among aromatic rings, polycyclic rings that include aromatic hydrocarbon rings and aromatic heterocycles are considered "aromatic heterocycles." "A group obtained by removing X hydrogen atoms from an aromatic ring" means a group obtained by removing X hydrogen atoms that are bonded to the atoms constituting the aromatic ring.

[0026] Ar １The number of ring members in the aromatic ring that gives the fragrance is not particularly limited, for example, 5 to 30, preferably 5 to 20, and more preferably 6 to 20. "Number of ring members" refers to the number of atoms that make up the ring structure, and in the case of polycyclic compounds, it refers to the number of atoms that make up this polycyclic compound. "Polycyclic compounds" include not only fused polycyclic compounds in which two rings have two shared atoms, but also ring-assembly type polycyclic compounds in which two rings do not have shared atoms and are connected by single bonds.

[0027] Ar １ Examples of aromatic rings that give off this fragrance include aromatic hydrocarbon rings with 6 to 30 members and aromatic heterocycles with 5 to 30 members.

[0028] Examples of the above aromatic hydrocarbon rings include benzene rings; condensed polycyclic aromatic hydrocarbon rings such as naphthalene rings, anthracene rings, fluorene rings, biphenylene rings, phenanthrene rings, and pyrene rings; ring-aggregated aromatic hydrocarbon rings such as biphenyl rings, terphenyl rings, binaphthalene rings, and phenylnaphthalene rings; and 9,10-ethanoanthracene rings.

[0029] Examples of the above-mentioned aromatic heterocycles include oxygen-containing heterocycles such as furan rings, pyran rings, benzofuran rings, and benzopyran rings; nitrogen-containing heterocycles such as pyridine rings, pyrimidine rings, and indole rings; and sulfur-containing heterocycles such as thiophene rings.

[0030] Ar １ As the aromatic ring that gives the fragrance, an aromatic hydrocarbon ring with 6 to 30 members is preferred, and a benzene ring is more preferred.

[0031] Ar １ The aromatic ring that gives the fragrance may have substituents other than the cyano group. Examples of other substituents include halogen groups such as fluoro groups and iodo groups, hydroxyl groups, carboxyl groups, nitro groups, alkyl groups, alkoxy groups, fluorinated alkyl groups (groups in which at least one hydrogen atom of an alkyl group is replaced with a fluorine atom), alkoxycarbonyl groups, alkoxycarbonyloxy groups, alkylsulfonyl groups, acyl groups, and acyloxy groups.

[0032] For a, 1 to 3 are preferred, and 1 or 2 are more preferred.

[0033] n is preferably 1 or 2, and more preferably 2. When n is 2, the sensitivity of the radiation-sensitive composition tends to be higher compared to when n is 1.

[0034] The number of cyano groups in the cation portion (i.e., a×n) is preferably 1 to 4, more preferably 1 to 3, and even more preferably 2 or 3. In particular, when a×n is 2 or more, the sensitivity of the radiation-sensitive composition tends to be improved and development defects are reduced compared to when a×n is 1.

[0035] "Hydrogen groups" include "aliphatic hydrocarbon groups" and "aromatic hydrocarbon groups." "Aliphatic hydrocarbon groups" include "chain hydrocarbon groups" and "alicyclic hydrocarbon groups." From another perspective, "aliphatic hydrocarbon groups" include "saturated hydrocarbon groups" and "unsaturated hydrocarbon groups." A "chain hydrocarbon group" is a hydrocarbon group that does not contain a ring structure and consists only of a chain structure, and includes both linear hydrocarbon groups and branched hydrocarbon groups. An "alicyclic hydrocarbon group" is a hydrocarbon group that contains only an alicyclic ring as its ring structure and does not contain an aromatic ring, and includes both monocyclic and polycyclic alicyclic hydrocarbon groups. However, it is not necessary to consist only of an alicyclic ring, and it may contain a chain structure as part of it. An "aromatic hydrocarbon group" is a hydrocarbon group that contains an aromatic ring as its ring structure. However, it is not necessary to consist only of an aromatic ring, and it may contain a chain structure or an alicyclic ring as part of it.

[0036] R １ Examples of hydrocarbon groups that provide this property include monovalent chain hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

[0037] Examples of monovalent chain hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, isobutyl, and tert-butyl groups; alkenyl groups such as ethenyl, propenyl, butenyl, and 2-methylpropa-1-en-1-yl groups; and alkynyl groups such as ethynyl, propynyl, and butynyl groups.

[0038] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic alicyclic saturated hydrocarbon groups such as cyclopentyl group and cyclohexyl group; polycyclic alicyclic saturated hydrocarbon groups such as norbornyl group, adamantyl group, tricyclodecyl group, and tetracyclododecyl group; monocyclic alicyclic unsaturated hydrocarbon groups such as cyclopentenyl group and cyclohexenyl group; and polycyclic alicyclic unsaturated hydrocarbon groups such as norbornenyl group, tricyclodecenyl group, and tetracyclododecenyl group.

[0039] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, and anthryl group; and aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group, and anthrylmethyl group.

[0040] R １ is preferably a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, more preferably a phenyl group.

[0041] R １ Examples of the substituent that R １ may have include those exemplified as the substituent that the aromatic ring having Ar １ may have. The substituent of R

[0042] is preferably a fluoro group, an iodo group, an alkoxy group, an alkylsulfonyl group, or a fluorinated alkyl group.

[0043] The cation moiety preferably has two or more cyano groups, or one cyano group and one or more electron-withdrawing groups. In these cases, the sensitivity and CDU tend to be more improved compared with the case of having only one cyano group. Examples of the electron-withdrawing group include halogeno groups such as fluoro group and iodo group, alkoxy group, fluorinated alkyl group (a group in which at least one hydrogen atom of the alkyl group is substituted with a fluorine atom), and alkylsulfonyl group.

[0044] M in the above formula (1) ＋ is S ＋In this case, the cation portion (sulfonium cation) is preferably a cation represented by the following formula (X-1) (hereinafter also referred to as "cation (X-1)").

[0045]

[0046] In the above formula (X-1), multiple Ar １ And each of the multiple as is independently equivalent to the above formula (1).

[0047] Examples of cations (X-1) include those represented by the following formulas (X-1-1) to (X-1-20).

[0048]

[0049] In the above formulas (X-1-4) and (X-1-10) to (X-1-13), "Me" represents a methyl group.

[0050] In the above formula (1), M ＋ I ＋ In this case, the cation portion (iodonium cation) is preferably a cation represented by the following formula (X-2) (hereinafter also referred to as "cation (X-2)").

[0051]

[0052] In the above formula (X-2), multiple Ar １ And each of the multiple as is independently equivalent to the above formula (1).

[0053] Examples of cations (X-2) include those represented by the following formulas (X-2-1) to (X-2-10).

[0054]

[0055] *1 - COO in the above formula (1) － The structure of the part represented by (anion part) is described in the section below, "<[A] Polymer>" where the polymer has a structural unit containing the substructure (x), and in the section below, "<[C] Acid Diffusion Control Agent>" where the acid diffusion control agent has a substructure (x).

[0056] The following describes each component contained in the radiation-sensitive composition.

[0057] <[A] Polymer> [A] polymer is a polymer whose solubility in a developer changes due to the action of an acid. The radiation-sensitive composition may contain one or more [A] polymers.

[0058] [A] Polymers typically have structural units containing acid-dissociable groups (hereinafter also referred to as "structural unit (I)"). [A] Polymers preferably have structural units containing phenolic hydroxyl groups (hereinafter also simply referred to as "structural unit (II)").

[0059] [A] A polymer may further have other structural units other than structural unit (I) and structural unit (II) (hereinafter also simply referred to as "other structural units"). [A] A polymer may have one or more of each structural unit.

[0060] Other structural units are structural units other than structural units (I) and structural units (II) described above. Examples of other structural units include structural units containing polar groups (hereinafter also referred to as "structural unit (III)"), structural units containing substructure (x) (hereinafter also referred to as "structural unit (IV)"), and structural units containing groups that generate sulfonic acid upon the action of radiation (hereinafter also referred to as "structural unit (V)").

[0061] In this specification, "structural unit" refers to one of the repeating units obtained by polymerizing monomers, and consists of a part that constitutes a main chain and side chains. "Main chain" refers to the longest atomic chain that makes up the polymer. "Side chain" refers to the atomic chains that make up the polymer other than the main chain.

[0062] The lower limit of the content of the [A] polymer in the radiation-sensitive composition is preferably 50% by mass, more preferably 70% by mass, and even more preferably 80% by mass, relative to all components other than the [D] organic solvent contained in the radiation-sensitive composition. The upper limit of the above content is preferably 99% by mass, and more preferably 95% by mass.

[0063] [A] The lower limit of the polystyrene-equivalent weight-average molecular weight (Mw) of the polymer determined by gel permeation chromatography (GPC) is preferably 1,000, more preferably 2,000, even more preferably 3,000, and even more preferably 5,000. The upper limit of the above Mw is preferably 30,000, more preferably 20,000, even more preferably 15,000, and even more preferably 10,000. By setting the Mw of the polymer [A] within the above range, the coating properties of the radiation-sensitive composition can be improved. The Mw of the polymer [A] can be adjusted, for example, by adjusting the type and amount of polymerization initiator used in the synthesis of the polymer [A].

[0064] [A] The upper limit of the ratio of Mw to the polystyrene-equivalent number-average molecular weight (Mn) of the polymer by GPC (hereinafter also referred to as "Mw / Mn") is preferably 2.5, more preferably 2.0, and even more preferably 1.9. The lower limit of the above ratio is usually 1.0, preferably 1.1, and more preferably 1.2.

[0065] [Method for measuring Mw and Mn] The Mw and Mn values ​​of polymers in this specification are measured using gel permeation chromatography (GPC) under the following conditions: GPC columns: Two "G2000HXL", one "G3000HXL", and one "G4000HXL" from Tosoh Corporation Column temperature: 40°C Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0066] [A] Polymers can be synthesized, for example, by polymerizing monomers that give each structural unit using known methods.

[0067] The following describes the various structural units of polymer [A].

[0068] [Structural Unit (I)] Structural unit (I) is a structural unit that contains an acid-dissociable group. An "acid-dissociable group" is a group that substitutes for a hydrogen atom in a carboxyl group and dissociates upon the action of an acid to give up a carboxyl group.

[0069] [A] The polymer has a structural unit (I) containing an acid-dissociable group, and thus exhibits the property that its solubility in a developer changes by the action of an acid. By the action of an acid generated from a radiation-sensitive acid-generating component by the action of radiation, the acid-dissociable group dissociates, and a difference in the solubility of the [A] polymer in the developer between the exposed portion and the unexposed portion occurs, whereby a resist pattern can be formed.

[0070] The acid-dissociable group is a group that substitutes a hydrogen atom of the carboxy group in the structural unit (I). In other words, in the structural unit (I), the acid-dissociable group is bonded to the etheric oxygen atom of the carbonyloxy group.

[0071] Examples of the acid-dissociable group include groups represented by the following formulas (a-1) to (a-2) (hereinafter, also referred to as "acid-dissociable groups (a-1) to (a-2)").

[0072]

[0073] In the above formulas (a-1) and (a-2), * indicates the bonding site with the etheric oxygen atom of the carbonyloxy group.

[0074] In the above formula (a-1), R Ｘ is a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms, or a group obtained by removing one hydrogen atom from a substituted or unsubstituted aromatic ring having 5 to 20 ring members. R Ｙ and R Ｚ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or these groups are combined with each other to form a saturated alicyclic ring having 3 to 20 ring members together with the carbon atom to which they are bonded.

[0075] In the above formula (a-2), R Ａ and R Ｂ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R Ａ and R Ｂ are combined with each other to form an unsaturated alicyclic ring having 3 to 20 ring members together with the carbon atom to which they are bonded. However, R Ｂ has a carbon atom constituting a carbon-carbon double bond at the α-position of the carbon atom bonded to *.

[0076] R Ｘ As a monovalent chain hydrocarbon group having 1 to 20 carbon atoms that gives the above-mentioned R １ Examples of hydrocarbon groups that provide this property include monovalent chain hydrocarbon groups having 1 to 20 carbon atoms.

[0077] R Ｘ As for aromatic rings with 5 to 20 members that give off fragrance, the above-mentioned Ar １ Examples of aromatic rings that provide fragrance include those mentioned above.

[0078] R Ｘ Substituents that the group represented by may have include, for example, halogen groups such as fluoro groups and iodo groups, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, and acyloxy groups.

[0079] R Ｙ , R Ｚ , R Ａ , or R Ｂ As a monovalent hydrocarbon group having 1 to 20 carbon atoms that gives the result, R １ Examples of hydrocarbon groups that give this include those shown below.

[0080] R Ｙ and R Ｚ Among saturated alicyclic rings with 3 to 20 members, formed by combining these rings with the carbon atoms to which they are bonded, examples of aliphatic hydrocarbon rings include monocyclic rings such as cyclopropane rings, cyclobutane rings, cyclopentane rings, and cyclohexane rings; and polycyclic rings such as norbornane rings, adamantane rings, tricyclodecane rings, and tetracyclododecane rings.

[0081] R Ｙ and R Ｚ Among saturated alicyclic rings with 3 to 20 members, formed by combining these rings with the carbon atoms to which they are bonded, examples of aliphatic heterocyclic rings include oxygen-containing heterocyclic rings such as tetrahydrofuran rings.

[0082] R Ａ and R ＢExamples of unsaturated alicyclic rings with 3 to 20 members, formed by combining these rings with the carbon atoms to which they are bonded, include monocyclic unsaturated alicyclic rings such as cyclobutene, cyclopentene, and cyclohexene structures, and polycyclic unsaturated alicyclic rings such as norbornene structures.

[0083] R Ｙ and R Ｚ If R is a monovalent hydrocarbon group having 1 to 20 carbon atoms, Ｙ and R Ｚ The preferred group is a chain-like hydrocarbon group, an alkyl group, and more preferably a methyl or ethyl group. Ｘ Preferably, the group is an aromatic ring with 5 to 20 members (substituted or unsubstituted) from which one hydrogen atom has been removed; more preferably, the group is an aromatic hydrocarbon ring with 6 to 20 members (substituted or unsubstituted) from which one hydrogen atom has been removed; and even more preferably, a phenyl group or an iodophenyl group.

[0084] R Ｙ and R Ｚ When these are combined with each other to form a saturated alicyclic ring with 3 to 20 member atoms, a cyclopentane ring is preferred as the saturated alicyclic ring. In this case, R Ｘ Alkyl groups are preferred, and methyl or i-propyl groups are more preferred.

[0085] R Ａ and R Ｂ For example, R Ａ and R Ｂ It is preferable that these elements are combined with each other to form an unsaturated alicyclic ring with 3 to 20 members, together with the carbon atoms to which they are bonded. In this case, a monocyclic unsaturated alicyclic ring is preferred, and a cyclohexene ring is more preferred.

[0086] Examples of acid-dissociable groups (a-1) include the groups represented by the following formulas (a-1-1) to (a-1-4). Examples of acid-dissociable groups (a-2) include the group represented by the following formula (a-2-1).

[0087]

[0088] Examples of structural units (I) include the structural unit represented by the following formula (I).

[0089]

[0090] In the above formula (I), R Ｈ１ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｈ The bond is a single bond, *-COO- or *-CONH-. * represents R Ｈ１ This indicates the bonding site with the carbon atom to which it is bonded. Ｈ２ R is a single bond, a divalent chain hydrocarbon group having 1 to 10 carbon atoms, or a group obtained by removing two hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 20 ring members. Ｈ３ This is the acid-dissociable group described above.

[0091] R Ｈ１ From the viewpoint of copolymerization of the monomer that gives structural unit (I), a hydrogen atom or a methyl group is preferred.

[0092] L Ｈ A single bond is preferred.

[0093] R Ｈ２ A single bond is preferred.

[0094] Specific examples of monomer structures that provide structural unit (I) include monomers (M-6) to (M-10) in the examples described later.

[0095] The lower limit of the content of structural unit (I) in polymer [A] is preferably 10 mol%, more preferably 20 mol%, and even more preferably 30 mol%, relative to the total structural units constituting polymer [A]. The upper limit of the above content is preferably 90 mol%, more preferably 80 mol%, and even more preferably 70 mol%.

[0096] [Structural Unit (II)] Structural unit (II) is a structural unit that contains a phenolic hydroxyl group. The term "phenolic hydroxyl group" refers not only to hydroxyl groups directly attached to a benzene ring, but to all hydroxyl groups directly attached to an aromatic ring.

[0097] In the case of KrF exposure, EUV exposure, or electron beam exposure, the presence of structural unit (II) in the [A] polymer can further enhance the sensitivity of the radiation-sensitive composition. Therefore, the radiation-sensitive composition can be suitably used as a radiation-sensitive composition for KrF exposure, EUV exposure, or electron beam exposure.

[0098] Examples of structural units (II) include the structural unit represented by the following formula (II).

[0099]

[0100] In the above formula (II), R Ｐ L is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. Ｐ The bond is a single bond, *-COO-, -O-, or *-CONH-. * is R Ｐ This indicates the bonding site with the carbon atom to which it is bonded. Ｐ This group is obtained by removing (p+1) hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring with 6 to 20 members. p is an integer from 1 to 3.

[0101] R Ｐ From the viewpoint of copolymerization of the monomer that gives structural unit (II), a hydrogen atom or a methyl group is preferred.

[0102] L Ｐ A single bond or an *-COO- bond is preferred.

[0103] Ar Ｐ As for aromatic hydrocarbon rings with 6 to 20 members that give ring membership, the above Ar １ Examples of aromatic hydrocarbon rings that give off fragrance include those with 6 to 20 members. Ｐ A benzene ring is preferred as the aromatic hydrocarbon ring that gives the above-mentioned property.

[0104] Ar Ｐ A substituent that may be present in the above aromatic hydrocarbon ring that gives is, for example, the above-mentioned R Ｘ Examples of substituents that the group represented by this symbol may have include those shown below.

[0105] For p, 1 or 2 is preferred.

[0106] Examples of structural units (II) include those represented by the following formulas (II-1) to (II-20).

[0107]

[0108] In the above formulas (II-1) to (II-20), R Ｐ This is equivalent to equation (II) above.

[0109] Specific examples of monomer structures that give structural unit (II) include monomers (M-1) to (M-5) in the examples described later.

[0110] The lower limit of the content of structural unit (II) in polymer [A] is preferably 10 mol%, and more preferably 20 mol%, relative to the total structural units constituting polymer [A]. The upper limit of the above content is preferably 70 mol%, and more preferably 60 mol%.

[0111] [Structural Unit (III)] Structural unit (III) is a structural unit containing a polar group. [A] The presence of structural unit (III) in the polymer allows for appropriate adjustment of its solubility in the developer. Examples of polar groups include lactone structures, cyclic carbonate structures, sultone structures or combinations thereof, alkoxy groups, and fluorinated alcohol groups.

[0112] Among structural units (III), structural units containing groups that include lactone structures, cyclic carbonate structures, sultone structures, or combinations thereof include, for example, structural units represented by the following formula.

[0113]

[0114]

[0115]

[0116]

[0117] In the above formula, R Ｌ１ These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0118] A specific example of a monomer that gives structural unit (III) is monomer (M-4) in the examples described later. Monomer (M-4) is a monomer that gives a structural unit containing a group with a lactone structure as a polar group.

[0119] [A] When polymer has structural unit (III), the lower limit of the content of structural unit (III) is preferably 5 mol%, more preferably 10 mol%, relative to the total structural units constituting polymer [A]. The upper limit of the above content is preferably 30 mol%, more preferably 20 mol%.

[0120] [Structural Unit (IV)] A structural unit (IV) is a structural unit that includes a substructure (x). When a polymer [A] has a structural unit (IV), the polymer [A] functions as an acid diffusion control agent. When a polymer [A] has a structural unit (IV), it generates carboxylic acids in response to radiation, and therefore, in a broad sense, it can also be called a "radiation-sensitive acid generator." However, the carboxylic acids generated from the substructure (x) in response to radiation do not dissociate the acid-dissociable groups under conditions where the acid generated from the acid generator [B] or the like dissociates the acid-dissociable groups, so a "radiation-sensitive acid generator" and an "acid diffusion control agent" are clearly distinguished.

[0121] Examples of structural units (IV) include structural units represented by the following formulas (IV-1) or (IV-2) (hereinafter also referred to as "structural unit (IV-1) or (IV-2)").

[0122]

[0123] In the above formulas (IV-1) and (IV-2), R ５ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ The bond is a single bond or an *-COO- bond. * is R ５ This shows the bonding site with the carbon atom to which it is bonded. A ＋ This represents the cation portion in formula (1) above.

[0124] In the above formula (IV-1), Ar ３ This group is obtained by removing two hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring with 6 to 20 members.

[0125] In the above formula (IV-2), R ６ and R ７ Each of these is independently a hydrogen atom, a fluoro group, a C1-C10 alkyl group, or a C1-C10 monovalent fluorinated alkyl group. １ n is an integer between 1 and 10. １ If there are two or more, multiple R ６ They are either identical or different from each other, and multiple R ７ They are either identical or different from each other. ８ and R ９ Each of these is independently a fluoro group or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. ２ n is an integer between 1 and 10. ２ If there are two or more, multiple R ８ They are either identical or different from each other, and multiple R ９ They are either identical or different from one another.

[0126] R ５ Hydrogen atoms or fluorine atoms are preferred as these elements.

[0127] L ２ *-COO- is preferred.

[0128] Ar ３ Examples of aromatic hydrocarbon rings with 6 to 20 members that give ring membership include the above-mentioned Ar １ Examples of aromatic hydrocarbon rings that give off fragrance include those with 6 to 20 members.

[0129] Ar ３ A benzene ring is preferred as the component.

[0130] Ar ３ A substituent that may be present in the above aromatic hydrocarbon ring that gives is, for example, the above-mentioned R Ｘ Examples of substituents that the group represented by this symbol may have include those shown below.

[0131] R ６ and R ７ Examples of alkyl groups having 1 to 10 carbon atoms, as represented by [the formula], include methyl, ethyl, and propyl groups.

[0132] R ６or R ７ A hydrogen atom or an ethyl group is preferred as the element.

[0133] n １ Of these, 1 to 5 are preferred, 1 to 3 are more preferred, and 1 is even more preferred.

[0134] R ８ or R ９ Examples of fluorinated alkyl groups having 1 to 10 carbon atoms, as represented by the formula, include perfluoroalkyl groups such as the trifluoromethyl group.

[0135] R ８ or R ９ A fluoro group is preferred as the component.

[0136] n ２ Of these, 1 to 5 are preferred, 1 to 3 are more preferred, and 1 is even more preferred.

[0137] When the structural unit (IV) is structural unit (IV-2), sensitivity and CDU tend to be improved, and development defects tend to be reduced, which is preferable.

[0138] Specific examples of monomers that provide structural units (IV) include monomers (M-13) to (M-14) in the examples described later.

[0139] [A] When the polymer has structural units (IV), the lower limit of the content of structural units (IV) is preferably 1 mol%, more preferably 5 mol%, relative to the total structural units constituting the polymer. The upper limit of the above content is preferably 20 mol%, more preferably 10 mol%.

[0140] [Structural Unit (V)] Structural unit (V) is a structural unit that contains a group that generates sulfonic acid upon the action of radiation. When polymer [A] has structural unit (V), polymer [A] functions as a radiation-sensitive acid generator in the radiation-sensitive composition. Furthermore, when polymer [A] has both structural unit (IV) and structural unit (V), polymer [A] functions as both a radiation-sensitive acid generator and an acid diffusion controller in the radiation-sensitive composition.

[0141] Groups that generate sulfonic acid through the action of the above-mentioned radiation include, for example, groups containing a sulfonate anion and a radiation-sensitive onium cation. Such groups are classified into two types: a structure in which the sulfonate anion is bonded to the side chain of the polymer (hereinafter also referred to as "structure 1") and a structure in which the radiation-sensitive onium cation is bonded to the side chain of the polymer (hereinafter also referred to as "structure 2"). Structure 1 is preferred as the structural unit (V).

[0142] Examples of radiation include those exemplified as radiation in the section on <Method for Forming Resist Patterns> described later.

[0143] When the group that generates sulfonic acid due to the action of the above-mentioned radiation corresponds to structure 1, an example of the structural unit (V) is the structural unit represented by the following formula (V).

[0144]

[0145] In the above formula (V), R Ｐ１ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｐ１ The bond is a single bond or an *-COO- bond. * is R Ｐ１ This indicates the bonding site with the carbon atom to which it is bonded. Ｐ２ n is a group obtained by removing two hydrogen atoms from a substituted or unsubstituted ring structure. Ｐ１ L is either 0 or 1. Ｐ２ R is a single bond or a divalent linking group. Ｐ３ and R Ｐ４ Each of these is independently a hydrogen atom, a fluoro group, a C1-C10 alkyl group, or a C1-C10 monovalent fluorinated alkyl group. Ｐ２ n is an integer between 0 and 10. Ｐ２ If there are two or more, multiple R Ｐ３ They are either identical or different from each other, and multiple R Ｐ４ They are either identical or different from each other. Ｐ５ and R Ｐ６ Each of these is independently a fluoro group or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. Ｐ３ n is an integer between 1 and 10. Ｐ３ If there are two or more, multiple R Ｐ５They are either identical or different from each other, and multiple R Ｐ６ They are either identical or different from each other. ＋ It is a monovalent radiation-sensitive onium cation.

[0146] R Ｐ１ From the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom or a methyl group is preferred.

[0147] R Ｐ２ The number of ring members in the ring structure that gives the property is preferably 5 to 30, and more preferably 6 to 30.

[0148] R Ｐ２ Examples of ring structures that give rise to this include aliphatic hydrocarbon rings, aliphatic heterocycles, aromatic hydrocarbon rings, and aromatic heterocycles.

[0149] Examples of the aliphatic hydrocarbon rings mentioned above include monocyclic saturated alicyclic rings such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, and cyclododecane rings; monocyclic unsaturated alicyclic rings such as cyclopentene, cyclohexene, cycloheptene, cyclooctene, and cyclodecene rings; polycyclic saturated alicyclic rings such as norbornane, adamantane, tricyclodecane, tetracyclododecane, and steroid structures; and polycyclic unsaturated alicyclic rings such as norbornene and tricyclodecene rings. A "steroid structure" refers to a structure whose basic skeleton is a stelane skeleton, which is a condensed skeleton of three six-membered rings and one five-membered ring.

[0150] Examples of the aliphatic heterocycles mentioned above include lactone rings such as hexanolactone rings and norbornanelactone rings; sultone rings such as hexanosultone rings and norbornanesultone rings; oxygen atom-containing heterocycles such as oxetane rings, tetrahydrofuran rings, dioxolane rings, oxacycloheptane rings and oxanorbornane rings; nitrogen atom-containing heterocycles such as azacyclohexane rings and diazabicyclooctane rings; and sulfur atom-containing heterocycles such as thiacyclohexane rings and thianorbornane rings.

[0151] Examples of the above aromatic hydrocarbon ring include the Ar mentioned above. １Examples of aromatic hydrocarbon rings that give off fragrance include those with 6 to 30 members.

[0152] Examples of the above aromatic heterocycles include the Ar mentioned above. １ Examples of aromatic heterocycles with 5 to 30 members that give off a fragrance include those that provide the fragrance.

[0153] A "linking group" refers to a group that links two or more structures. Linking groups remain in the structure of a compound or polymer due to the synthetic materials or methods used, etc., and do not affect the effects of the present invention, or have only a very small effect. This does not mean that all structures other than linking groups contribute to the performance of the effects of the present invention.

[0154] As a divalent linking group, L Ｐ２ The group linking the two structures to which the two bonds are attached is not particularly limited, and examples include carbonyl groups, ether groups, carbonyloxy groups, sulfide groups, sulfonyl groups, alkanediyl groups having 1 to 10 carbon atoms, or groups that are combinations thereof.

[0155] R Ｐ３ and R Ｐ４ Examples of alkyl groups having 1 to 10 carbon atoms, as represented by [the formula], include methyl, ethyl, and propyl groups.

[0156] R Ｐ３ , R Ｐ４ , R Ｐ５ or R Ｐ６ Examples of fluorinated alkyl groups having 1 to 10 carbon atoms, as represented by the formula, include perfluoroalkyl groups such as the trifluoromethyl group.

[0157] M ＋ The monovalent radiosensitive onium cation represented by is not particularly limited as long as it is known as a radiosensitive onium cation in onium salts used as radiosensitive acid generators contained in radiosensitive compositions. For example, a sulfonium cation (S ＋ ), iodonium cation (I ＋ ) are examples. Alternatively, the cation portion described in the section [Substructure (x)] above may also be used.

[0158] In addition to those exemplified as the cation portion in the section [Substructure (x)] above, examples of the above radiation-sensitive onium cation include cations represented by the following formulas (r-1) to (r-7).

[0159]

[0160] Specific examples of monomer structures that provide structural units (V) include monomers (M-11) to (M-12) in the examples described later.

[0161] The lower limit of the content of structural units (V) in polymer [A] is preferably 0.5 mol%, more preferably 1 mol%, even more preferably 2 mol%, and particularly preferably 5 mol%, relative to the total structural units constituting polymer [A]. The upper limit of the above content is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%.

[0162] <[B] Acid Generator> The [B] acid generator is a substance that generates acid upon exposure. Examples of radiation used for exposure include those exemplified as radiation in the <Method for Forming Resist Patterns> section described later. The acid generated by exposure causes the acid-dissociable groups of the [A] polymer to dissociate, generating carboxyl groups, which creates a difference in the solubility of the resist film in the developer between the exposed and unexposed areas, thereby forming a resist pattern. The radiation-sensitive composition may contain one or more [B] acid generators.

[0163] The radiation-sensitive composition may or may not contain [B] an acid-generating agent. If the radiation-sensitive composition does not contain [B] an acid-generating agent, it is preferable that the [A] polymer has structural units (V). In other words, it is preferable that the radiation-sensitive composition contains a component having a structure that generates acid upon exposure.

[0164] [B] Examples of acids generated from the acid generator include sulfonic acid and imido acid.

[0165] [B] The acid generator is not particularly limited as long as it is used as a radiation-sensitive acid generator contained in the radiation-sensitive composition, and examples include onium salt compounds, N-sulfonyloxyimide compounds, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, etc.

[0166] Examples of onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts.

[0167] [B] Specific examples of acid generators include, for example, the compounds described in paragraphs

[0080] to

[0113] of Japanese Patent Application Publication No. 2009-134088.

[0168] [B] As an acid generator, an onium salt compound is preferred, and an onium salt compound consisting of a radiation-sensitive onium cation and an organic acid anion is more preferred.

[0169] Examples of acid generators that produce sulfonic acid upon exposure include compounds represented by the following formula (3).

[0170]

[0171] In the above formula (3), R Ｐ７ L is a group obtained by removing one hydrogen atom from a substituted or unsubstituted ring structure. Ｐ２ , R Ｐ３ , R Ｐ４ , R Ｐ５ , R Ｐ６ , n Ｐ２ , n Ｐ３ and M ＋ This is equivalent to equation (V) above.

[0172] R Ｐ７ The number of ring members in the ring structure that gives the property is preferably 5 to 30, and more preferably 6 to 30.

[0173] R Ｐ７ Examples of ring structures that give this structure include the above R ｐ２ Examples of ring structures that give this result include the following:

[0174] R Ｐ７A substituent that may be present in the ring structure that gives the result is, for example, the R mentioned above. Ｘ Examples of substituents that may be present include groups containing acid-dissociable groups.

[0175] [B]Specific examples of anions of acid generators that generate sulfonic acid upon exposure include, for example, the anions represented by the following formulas (3-1) to (3-7).

[0176]

[0177] [B] As the acid generator, a compound obtained by appropriately combining the above-mentioned radiation-sensitive onium cation and the above-mentioned anion can be used.

[0178] Furthermore, the above-mentioned radiation-sensitive onium cation can be the cation portion described in the section on [Structural Unit (V)] above.

[0179] [B] Specific structures of the acid generators include, for example, the acid generators (B-1) to (B-7) in the examples described later.

[0180] The lower limit of the content of the [B] acid generator in the radiation-sensitive composition is preferably 10 parts by mass, more preferably 20 parts by mass, and even more preferably 30 parts by mass, per 100 parts by mass of the [A] polymer. The upper limit of the above content is preferably 100 parts by mass, more preferably 80 parts by mass, and even more preferably 70 parts by mass.

[0181] <[C] Acid Diffusion Control Agent> The [C] acid diffusion control agent controls the diffusion phenomenon of acids generated from the [B] acid generator, etc., in the resist film upon exposure, and controls undesirable chemical reactions in the unexposed areas. The radiation-sensitive composition may contain one or more [C] acid diffusion control agents.

[0182] [C] Examples of acid diffusion control agents include nitrogen atom-containing compounds and compounds having a radiation-sensitive onium cation and an organic acid anion (hereinafter also referred to as "photodecayable bases").

[0183] Examples of nitrogen atom-containing compounds include amine compounds such as tripentylamine and trioctylamine, amide group-containing compounds such as formamide and N,N-dimethylacetamide, urea compounds such as urea and 1,1-dimethylurea, and nitrogen-containing heterocyclic compounds such as pyridine, N-(undecylcarbonyloxyethyl)morpholine and N-t-pentyloxycarbonyl-4-hydroxypiperidine.

[0184] The photo-decaying base generates a weak acid in the exposed area, increasing the solubility or insolubility of the [A] polymer in the developer, and consequently suppressing the roughness of the surface in the exposed area after development. On the other hand, in the unexposed area, the anion exhibits a high acid-catching function, acting as a quencher and capturing the acid diffusing from the exposed area.

[0185] The radioactive onium cation in a photodecayable base is not particularly limited as long as it is known as a radioactive onium cation in an onium salt used as a radioactive acid generator contained in a radioactive composition. For example, a sulfonium cation (S ＋ ), iodonium cation (I ＋ ) are examples. Alternatively, the cation portion described in the section [Substructure (x)] above may also be used.

[0186] The organic acid anions used in photodecayable bases are not particularly limited as long as they are used as organic acid anions in photodecayable bases; for example, carboxylic acid anions can be used.

[0187] As the photodecayable base, a compound obtained by appropriately combining the above-mentioned radiation-sensitive onium cation and the above-mentioned anion can be used.

[0188] Furthermore, the [C] acid diffusion control agent may be a compound containing the aforementioned substructure (x).

[0189] Examples of compounds containing substructure (x) include the compound represented by the following formula (1-1).

[0190]

[0191] In the above formula (1-1), M ＋Ar １ , R １ , m, n, and a are equivalent to those in formula (1) above. An － It is a carboxylic acid anion.

[0192] An － One embodiment of the carboxylic acid anion represented by the formula (2-1) below (hereinafter also referred to as the "aromatic carboxylic acid anion") is the anion represented by the formula (2-1) below. In this case, sensitivity tends to be improved.

[0193]

[0194] In the above formula (2-1), Ar ２ This is a group obtained by removing one hydrogen atom from a substituted or unsubstituted aromatic ring.

[0195] Ar ２ As for the aromatic ring that gives off the fragrance, the above-mentioned Ar １ Examples of aromatic rings that provide fragrance include those mentioned above.

[0196] Ar ２ As the aromatic ring that gives the fragrance, an aromatic hydrocarbon ring with 6 to 30 members is preferred, and a benzene ring is more preferred.

[0197] Ar ２ Substituents that may be present in the aromatic ring that gives the fragrance include, for example, fluoro groups, halogen groups such as iodo groups, hydroxyl groups, carboxyl groups, nitro groups, alkyl groups, aryl groups, alkoxy groups, fluorinated alkyl groups (groups in which at least one hydrogen atom of an alkyl group is replaced with a fluorine atom), alkoxycarbonyl groups, alkoxycarbonyloxy groups, alkylsulfonyl groups, acyl groups, acyloxy groups, and groups that are combinations of these.

[0198] Ar ２ When the aromatic ring that gives the fragrance has multiple substituents, the substituents are bonded to each other and form Ar ２ It may form a ring structure with the carbon atoms above. An example of such a ring structure is a 1,3-dioxolane ring.

[0199] Ar ２The aromatic ring that gives the fragrance preferably has at least one group selected from the group consisting of an iodo group, a hydroxyl group, a methoxy group, a carboxyl group, and an iodophenylmethoxy group as a substituent. In particular, Ar ２ Compared to cases where the aromatic ring giving the fragrance has hydroxyl and trifluoromethyl groups as substituents, the CDU tends to be higher.

[0200] Ar ２ The aromatic ring that gives the effect tends to have improved sensitivity and CDU when it has an iodine group as a substituent.

[0201] Ar ２ The aromatic ring that gives the product may also preferably have two hydroxyl groups as substituents. In this case, compared to the case where there is one hydroxyl group as substituent, the sensitivity tends to be improved and development defects can be reduced.

[0202] Examples of the above-mentioned aromatic carboxylic acid anions include those represented by the following formulas (2-1-1) to (2-1-12).

[0203]

[0204] An － One embodiment of the carboxylic acid anion represented by the formula (2-2) below is the anion represented by the formula (2-2) below (hereinafter also referred to as the "aliphatic carboxylic acid anion"). In this case, sensitivity tends to be improved.

[0205]

[0206] In the above equation (2-2), R ２ L is a group obtained by removing one hydrogen atom from a substituted or unsubstituted ring structure. １ R is a single bond or a divalent linking group. ３ and R ４ Each of these is independently a hydrogen atom, a fluoro group, a hydroxyl group, a C1-C10 alkyl group, a C1-C10 alkoxy group, or a C1-C10 monovalent fluorinated alkyl group. b is an integer from 1 to 10. If b is 2 or more, multiple R ３ They are either identical or different from each other, and multiple R ４ They are either identical or different from one another.

[0207] R ２ The number of ring members in the ring structure that gives the property is preferably 5 to 30, and more preferably 6 to 30.

[0208] R ２ The ring structure that gives this is the aforementioned R Ｐ２ Examples of ring structures that give this result include the following:

[0209] As a divalent linking group, L ２ The group linking the two structures to which the two bonds are attached is not particularly limited, and examples include carbonyl groups, ether groups, carbonyloxy groups, sulfide groups, sulfonyl groups, alkanediyl groups having 1 to 10 carbon atoms, or groups that are combinations thereof.

[0210] R ３ and R ４ Examples of alkyl groups having 1 to 10 carbon atoms, as represented by [the formula], include methyl, ethyl, and propyl groups.

[0211] R ３ and R ４ Examples of fluorinated alkyl groups having 1 to 10 carbon atoms, as represented by the formula, include perfluoroalkyl groups such as the trifluoromethyl group.

[0212] R ３ and R ４ Examples of alkoxy groups having 1 to 10 carbon atoms represented by this formula include the methoxy group.

[0213] For b, 1 to 5 is preferred, 1 to 3 is more preferred, 1 or 2 is even more preferred, and 1 is even more preferred.

[0214] If b is 1, R ３ is a fluoro group and R ４ A form in which R is a hydrogen atom, a hydroxyl group, or a methoxy group. ３ is a trifluoromethyl group and R ４ A mode in which is a hydrogen atom, a trifluoromethyl group, a hydroxyl group, or a methoxy group, or R ３ is a pentafluoroethyl group and R ４ A configuration in which is a hydrogen atom is preferred.

[0215] If b is 2, R ３ and R ４ A configuration in which both are fluorogroups is preferred.

[0216] Also, - (CR ３ R ４ ) ｂ The group represented by - is -COO － It is preferable that the fluoro group is located only on the carbon atom directly connected to it.

[0217] Examples of the above-mentioned aliphatic carboxylic acid anions include those represented by the following formulas (2-2-1) to (2-2-7).

[0218]

[0219] [C] Specific structures of the acid diffusion control agents include, for example, the acid diffusion control agents (C-1) to (C-18) and (RC-1) to (RC-3) in the examples described later. Of these, the acid diffusion control agents (RC-1) to (RC-3) are compounds that do not have the above-mentioned substructure (x).

[0220] If the radiation-sensitive composition contains a [C] acid diffusion control agent, the lower limit of the [C] acid diffusion control agent content in the radiation-sensitive composition is preferably 5 mol%, and more preferably 10 mol%, based on 100 mol% of the radiation-sensitive acid generator (total if there are multiple). The upper limit of the above content is preferably 100 mol%, and more preferably 80 mol%.

[0221] <[D] Organic Solvents> The radiation-sensitive composition typically contains [D] organic solvents. [D] organic solvents are not particularly limited as long as they are capable of dissolving or dispersing at least [A] polymers, and optionally [B] acid generators, [C] acid diffusion control agents, and other optional components.

[0222] Examples of [D] organic solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents. The radiation-sensitive composition may contain one or more [D] organic solvents.

[0223] Examples of alcohol-based solvents include aliphatic monoalcohol solvents such as 4-methyl-2-pentanol, n-hexanol, diacetone alcohol, and methyl 2-hydroxyisobutyrate; alicyclic monoalcohol solvents such as cyclohexanol; polyhydric alcohol solvents such as 1,2-propylene glycol; and polyhydric alcohol partial ether solvents such as propylene glycol monomethyl ether.

[0224] Examples of ether-based solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; and aromatic ring-containing ether solvents such as diphenyl ether and anisole.

[0225] Examples of ketone solvents include linear ketone solvents such as acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-iso-butyl ketone, and trimethylnonanone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone; and 2,4-pentanedione, acetonylacetone, and acetophenone.

[0226] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain-like amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0227] Examples of ester solvents include monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; lactone solvents such as γ-butyrolactone and valerolactone; polyhydric alcohol carboxylate solvents such as propylene glycol acetate; polyhydric alcohol partial ether carboxylate solvents such as propylene glycol monomethyl ether acetate; polyhydric carboxylic acid diester solvents such as diethyl oxalate; and carbonate solvents such as dimethyl carbonate and diethyl carbonate.

[0228] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane and n-hexane, and aromatic hydrocarbon solvents such as toluene and xylene.

[0229] [D] As organic solvents, alcohol-based solvents, ester-based solvents or combinations thereof are preferred, aliphatic monoalcohol-based solvents, polyhydric alcohol partial ether-based solvents, polyhydric alcohol partial ether carboxylate-based solvents or combinations thereof are more preferred, and methyl 2-hydroxyisobutyrate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate or combinations thereof are even more preferred.

[0230] If the radiation-sensitive composition contains an organic solvent [D], the lower limit of the content of the organic solvent [D] is preferably 50% by mass, more preferably 60% by mass, even more preferably 70% by mass, and particularly preferably 80% by mass, relative to the total components contained in the radiation-sensitive composition. The upper limit of the above content is preferably 99.9% by mass, more preferably 99.5% by mass, and even more preferably 99.0% by mass.

[0231] <Other optional components> Other optional components include polymers and surfactants with a higher fluorine atom content than polymer [A]. The radiation-sensitive composition may contain one or more other optional components.

[0232] <Method for forming a resist pattern> The resist pattern formation method comprises the steps of directly or indirectly coating a substrate with a radiation-sensitive composition (hereinafter also referred to as the "coating step"), exposing the resist film formed by the coating step (hereinafter also referred to as the "exposure step"), and developing the exposed resist film (hereinafter also referred to as the "development step").

[0233] In the above coating process, the aforementioned radiation-sensitive composition is used as the radiation-sensitive composition. Therefore, according to this resist pattern formation method, a resist pattern with good sensitivity, LWR, and resolution can be formed.

[0234] The following describes each step of the resist pattern formation method.

[0235] [Coating Process] In this process, a radiation-sensitive composition is coated onto the substrate directly or indirectly. This forms a resist film on the substrate directly or indirectly.

[0236] In this process, the above-mentioned radiation-sensitive composition is used as the radiation-sensitive composition.

[0237] Examples of substrates include silicon wafers, silicon dioxide wafers, and aluminum-coated wafers.

[0238] Examples of coating methods include rotary coating (spin coating), casting coating, and roll coating. After coating, pre-baking (hereinafter also referred to as "PB") may be performed as needed to volatilize the solvent in the coating film. The temperature and duration of PB are not particularly limited, for example, it may be performed at a temperature of 60°C to 150°C for a period of 5 seconds to 300 seconds. The average thickness of the formed resist film is not particularly limited, for example, it may be between 10 nm and 1,000 nm.

[0239] [Exposure Process] In this process, the resist film formed by the coating process described above is exposed. This exposure is performed by irradiating the film with radiation through a photomask (or, in some cases, through an immersion medium such as water). The radiation can be appropriately selected according to the line width and diameter of the desired pattern, and examples include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays. Among these, far ultraviolet light, EUV, or electron beams are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV (wavelength 13.5 nm), or electron beams are more preferred, KrF excimer laser light, EUV, or electron beams are even more preferred, and EUV or electron beams are particularly preferred.

[0240] After the exposure described above, it is preferable to perform a post-exposure bake (hereinafter also referred to as "PEB"). This PEB can increase the difference in solubility in the developer between the exposed and unexposed areas. The temperature and duration of the PEB are not particularly limited; for example, it can be performed at a temperature of 50°C to 180°C for a period of 5 seconds to 600 seconds.

[0241] [Development Process] In this process, the exposed resist film is developed. This allows for the formation of a predetermined resist pattern. The development method in the development process may be alkaline development or organic solvent development.

[0242] In the case of alkaline development, examples of developer solutions include alkaline aqueous solutions containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (hereinafter also referred to as "TMAH"), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, aqueous TMAH solutions are preferred, and 2.38% by mass aqueous TMAH solutions are more preferred.

[0243] In the case of organic solvent development, examples of the developing solution include the organic solvent exemplified as [D] organic solvent in the above-mentioned radiation-sensitive composition.

[0244] <Compound> This compound is described in the section above under <[C] Acid Diffusion Control Agent> as a compound containing substructure (x). This compound can be suitably used as an acid diffusion control agent for radiation-sensitive compositions.

[0245] Specific structures of the compounds in question include, for example, compounds (C-1) to (C-18) in the examples described later.

[0246] <Polymer> The polymer is described in the section <[A] Polymer> above as a polymer having a structural unit including a substructure (x). The polymer can be suitably used as a base resin and acid diffusion control agent for radiation-sensitive compositions.

[0247] Specific examples of the polymer include polymers (A-12) to (A-14) in the examples described later.

[0248] <Monomer> The monomer is a monomer represented by the following formula (iv-1) or (iv-2).

[0249]

[0250] In the above formulas (iv-1) and (iv-2), R ５ , L ２ , *, and A ＋ This is equivalent to the above formulas (IV-1) and (IV-2).

[0251] In the above formula (iv-1), Ar ３ This is equivalent to the above formula (IV-1).

[0252] In the above formula (iv-2), R ６ , R ７ , n １ , R ８ , R ９ , n ２ This is equivalent to the above formula (IV-2).

[0253] Specific examples of the monomer include the polymers (M-13) to (M-14) in the examples described later.

[0254] The present invention will be described in detail below based on examples. The present invention is not limited to these examples.

[0255] <[C] Synthesis of Acid Diffusion Control Agents> Compounds represented by the following formulas (C-1) to (C-18) (hereinafter also referred to as "acid diffusion control agents (C-1) to (C-18)") were synthesized according to the following method.

[0256]

[0257]

[0258] [Synthesis Example 1-1] Synthesis of Acid Diffusion Control Agent (C-1) The acid diffusion control agent (C-1) was synthesized according to the reaction scheme below.

[0259]

[0260] Compound (PPPC-1) (16 mmol) and benzene (80 mmol) were added to a container containing dichloromethane (30 mL) and cooled on ice. Trifluoromethanesulfonic anhydride (18 mmol) was added dropwise, and the mixture was stirred at room temperature for 5 hours. After cooling on ice, 100 mL of ultrapure water was added. After stirring, the aqueous layer was removed, and the organic layer was washed three times with 100 mL of ultrapure water. The resulting organic layer was then concentrated to dryness. Dichloromethane (15 mL) and diisopropyl ether (30 mL) were added, and the mixture was stirred for 30 minutes. The precipitated solid was filtered to obtain compound (PPC-1).

[0261] Compound (PPC-1) (10 mmol) was reacted with Sigma-Aldrich's "Sephadex QAE A-25" in the presence of methanol, and the solvent was removed by distillation to obtain compound (PC-1).

[0262] Compound (PC-1) (10 mmol) and compound (P-1) (10 mmol) were added to a container containing dichloromethane (50 mL) and ultrapure water (50 mL). After stirring at room temperature for 30 minutes, the aqueous layer was removed, and the organic layer was washed three times with 50 mL of ultrapure water. The resulting organic layer was concentrated to dryness to obtain the acid diffusion control agent (C-1).

[0263] [Synthesis Examples 1-2 to 1-17] Acid diffusion control agents (C-2) to (C-17) were synthesized in the same manner as in Synthesis Example 1-1, except that the synthesis precursors of the acid diffusion control agents (C-2) to (C-17) were appropriately selected.

[0264] [Synthesis Example 1-18] Synthesis of Acid Diffusion Control Agent (C-18) The acid diffusion control agent (C-18) was synthesized according to the reaction scheme below.

[0265]

[0266] Compound (PC-18) (10 mmol) and compound (P-18) (10 mmol) were added to a container containing dichloromethane (50 mL) and ultrapure water (50 mL). After stirring at room temperature for 30 minutes, the aqueous layer was removed, and the organic layer was washed three times with 50 mL of ultrapure water. The resulting organic layer was concentrated to dryness to obtain the acid diffusion control agent (C-18).

[0267] <Synthesis of Polymers [A]> Polymers (A-1) to (A-14) were synthesized according to the following method. Compounds represented by the following formulas (M-1) to (M-14) (hereinafter also referred to as "monomers (M-1) to (M-14)") were used for the synthesis of polymers [A]. The Mw and Mw / Mn of the obtained polymers [A] were confirmed by GPC as described in the section [Method for measuring Mw and Mn] above. Monomers (M-13) and (M-14) are monomers having the above-mentioned substructure (x). Monomers (M-13) and (M-14) were synthesized in the same manner as in Synthesis Example 1-1, except that the precursor was appropriately selected.

[0268]

[0269] [Synthesis Example 2-1] The monomers (M-6) and (M-2) of polymer (A-1) were dissolved in propylene glycol monomethyl ether (200 parts by mass relative to the total amount of monomer) so that the molar ratio in the final polymer was 55 / 45. Next, azobisisobutyronitrile was added as an initiator at a concentration of 6 mol% relative to the total amount of monomer to prepare a monomer solution. Meanwhile, propylene glycol monomethyl ether (100 parts by mass relative to the total amount of monomer) was added to an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 85°C for another 3 hours. After the polymerization reaction was complete, the polymerization solution was cooled to room temperature.

[0270] The cooled polymerization solution was added to hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane (100 parts by mass relative to the polymerization solution), and then dried at 50°C for 12 hours to obtain a white powdery polymer (A-1).

[0271] [Synthesis Examples 2-2 to 2-14] Synthesis of polymers (A-2) to (A-14) Polymers (A-2) to (A-14) were synthesized in the same manner as in Synthesis Example 2-1, except that the types of components shown in Table 1 below were used.

[0272] Table 1 below shows the types and amounts (in mol%) of monomers that give each structural unit of the [A] polymer obtained in Synthesis Examples 2-1 to 2-14, as well as Mw and Mw / Mn. In Table 1 below, "-" indicates that the corresponding monomer was not used.

[0273]

[0274] <Preparation of Radiation-Sensitive Composition> The components used in the preparation of the radiation-sensitive composition are shown below. In the following examples and comparative examples, unless otherwise specified, "parts by mass" refers to the value when the mass of the [A] polymer used is 100 parts by mass.

[0275] [A polymer] Polymers (A-1) to (A-14) were used as [A] polymers.

[0276] [[B] Acid Generator] As the acid generator, compounds represented by the following formulas (B-1) to (B-7) (hereinafter also referred to as "acid generators (B-1) to (B-7)") were used.

[0277]

[0278] [C] Acid Diffusion Control Agents As acid diffusion control agents, acid diffusion control agents (C-1) to (C-18) and compounds represented by the following formulas (RC-1) to (RC-3) (hereinafter also referred to as "acid diffusion control agents (RC-1) to (RC-3)") were used. Note that acid diffusion control agents (RC-1) to (RC-3) are compounds that do not have the above-mentioned substructure (x).

[0279]

[0280] [D] Organic solvents The following organic solvents were used as [D] organic solvents: (D-1): Propylene glycol monomethyl ether acetate (D-2): Propylene glycol monomethyl ether (D-3): Methyl 2-hydroxyisobutyrate

[0281] [Example 1] Preparation of Radiation-Sensitive Composition (R-1) 100 parts by mass of (A-1) as a polymer, 60 parts by mass of (B-1) as an acid generator, 70 mol% of (C-1) as an acid diffusion controller with respect to (B-1), and 5,500 parts by mass of (D-1) and 1,500 parts by mass of (D-2) as organic solvents were mixed. The obtained mixture was filtered through a filter with a pore size of 0.2 μm to prepare a radiation-sensitive composition (R-1).

[0282] [Examples 2 to 37 and Comparative Examples 1 to 3] Preparation of Radiation-Sensitive Compositions (R-2) to (R-37) and (CR-1) to (CR-3) Radiation-sensitive compositions (R-2) to (R-37) and (CR-1) to (CR-3) were prepared in the same manner as in Example 1, except that the components of the types and contents shown in Table 2 below were used.

[0283] In Table 2 below, "-" indicates that the corresponding component is not used. In Table 2 below, the content ratio of [C] acid diffusion controller means the molar ratio with respect to the radiation-sensitive acid generator (the total in the case of multiple).

[0284]

[0285] <Formation of Resist Pattern>On the surface of a 12-inch silicon wafer on which an underlayer film (AL412 (manufactured by Brewer Science)) with a film thickness of 40 nm was formed, each of the above-prepared radiation-sensitive compositions was coated using a spin coater ("CLEAN TRACK ACT12" of Tokyo Electron Limited). After performing PB at 130°C for 60 seconds, it was cooled at 23°C for 30 seconds to form a resist film with a film thickness of 45 nm. This resist film was irradiated with EUV using an EUV scanner ("NXE3300" of ASML, NA 0.33, σ 0.9 / 0.6, quadrupole illumination, mask with a hole pattern having a pitch of 50 nm and a +20% bias on the wafer). The above resist film was subjected to PEB at 105°C for 60 seconds. Then, development was performed for 30 seconds using a 2.38 mass% aqueous TMAH solution to form a resist pattern with a 25 nm hole and a 50 nm pitch (hereinafter, also referred to as "25 nm contact hole pattern").

[0286] <Evaluation> Sensitivity, CDU, and development defects were evaluated according to the following method. The results are shown in Table 3 below.

[0287] [Sensitivity] In the section <Formation of Resist Pattern> above, the exposure dose at which the resist pattern was formed was taken as the optimum exposure dose, and this value was taken as the sensitivity (unit: mJ / cm ２ ). A smaller value of sensitivity indicates better performance. If the sensitivity is less than 59 mJ / cm ２ , it was evaluated as "A" (extremely good); if it is 59 mJ / cm ２ or more and 62 mJ / cm ２ or less, it was evaluated as "B" (good); if it exceeds 62 mJ / cm ２ , it was evaluated as "C" (bad).

[0288] [CDU] The resist pattern formed in the section <Formation of Resist Pattern> above was observed from the top of the pattern using a scanning electron microscope ("CG-4100" of Hitachi High-Tech Corporation), and a total of 800 hole diameters were measured at arbitrary points. The dimensional variation (3σ) was determined, and this was taken as the CDU (unit: nm). A smaller value of CDU indicates that the variation in hole diameter over a long period is smaller and better. If the CDU is less than 3.3 nm, it was evaluated as "A" (extremely good); if it is 3.3 nm or more and less than 3.6 nm, it was evaluated as "B" (good); if it is 3.6 nm or more, it was evaluated as "C" (bad).

[0289] [Development Defects] The number of defects in the resist pattern formed in the section <Formation of Resist Pattern> above was measured using a defect inspection apparatus ("KLA2810" of KLA-Tencor Corporation). Then, the measured defects were classified into those determined to be derived from the resist film and foreign substances derived from the external environment. If the number of defects determined to be derived from the resist film is less than 30, the development defects were evaluated as "A" (extremely good); if it is 30 or more and 50 or less, it was evaluated as "B" (good); if it exceeds 50, it was evaluated as "C" (bad).

[0290]

Claims

1. A radiation-sensitive composition containing a polymer whose solubility in a developer changes by the action of an acid, wherein the polymer, a component other than the polymer, or both have a partial structure represented by the following formula (1). (In formula (1), M ＋ is S ＋ or I ＋ . n is an integer of 1 or more and m or less. When M ＋ is S ＋ , m is 3, and when M ＋ is I ＋ , m is 2. Ar １ is a group obtained by removing (a + 1) hydrogen atoms from a substituted or unsubstituted aromatic ring. When n is 2 or 3, the plurality of Ar １ are the same or different. a is an integer of 1 to 5. R １ is a substituted or unsubstituted hydrocarbon group. When m - n is 2, the two R １ are the same or different. *1 indicates a bonding site.) 2. The radiation-sensitive composition according to claim 1, which contains a compound comprising the above-mentioned substructure as a component other than the polymer.

3. The radiation-sensitive composition according to claim 2, wherein the above compound is represented by the following formula (1-1). (In formula (1-1), M ＋ Ar １ , R １ , m, n, and a are equivalent to those in formula (1) above. An － (This is a carboxylic acid anion.) 4. An in the above formula (1-1) － The radiation-sensitive composition according to claim 3, wherein the element is represented by the following formula (2-1). (In the above formula (2-1), Ar ２ (This is a group obtained by removing one hydrogen atom from a substituted or unsubstituted aromatic ring.) 5. Ar in the above formula (2-1) ２ However, it has at least one substituent selected from the group consisting of an iodine group, a hydroxyl group, a methoxy group, a carboxyl group, and an iodophenylmethoxy group, or multiple substituents are bonded to each other in an Ar ２ The radiation-sensitive composition according to claim 4, wherein a 1,3-dioxolane ring is formed together with the carbon atom above.

6. An in the above formula (1-1) － The radiation-sensitive composition according to claim 3, wherein the ratio is represented by the following formula (2-2). (In the above equation (2-2), R ２ L is a group obtained by removing one hydrogen atom from a substituted or unsubstituted ring structure. １ R is a single bond or a divalent linking group. ３ and R ４ Each of these is independently a hydrogen atom, a fluoro group, a C1-C10 alkyl group, or a C1-C10 monovalent fluorinated alkyl group. b is an integer from 1 to 10. If b is 2 or more, multiple R ３ They are either identical or different from each other, and multiple R ４ They are either identical or different from one another.

7. In the above equation (2-2), b is 1, and R ３ and R ４ The radiation-sensitive composition according to claim 6, wherein each is independently a fluoro group or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms.

8. The radiation-sensitive composition according to claim 1, wherein the polymer has a structural unit comprising the substructure described above.

9. The radiation-sensitive composition according to claim 8, wherein the above structural unit is represented by the following formula (IV-1) or (IV-2). (In formulas (IV-1) and (IV-2), R ５ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ The bond is a single bond or an *-COO- bond. * is R ５ This shows the bonding site with the carbon atom to which it is bonded. A ＋ represents the cation portion in formula (1) above. In formula (IV-1), Ar ３ R is a group obtained by removing two hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 20 members. In formula (IV-2), R ６ and R ７ Each of these is independently a hydrogen atom, a fluoro group, a C1-C10 alkyl group, or a C1-C10 monovalent fluorinated alkyl group. １ n is an integer between 1 and 10. １ If there are two or more, multiple R ６ They are either identical or different from each other, and multiple R ７ They are either identical or different from each other. ８ and R ９ Each of these is independently a fluoro group or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. ２ n is an integer between 1 and 10. ２ If there are two or more, multiple R ８ They are either identical or different from each other, and multiple R ９ They are either identical or different from one another.

10. A method for forming a resist pattern, comprising the steps of: coating a substrate directly or indirectly with a radiation-sensitive composition according to any one of claims 1 to 9; exposing a resist film formed by the above coating; and developing the exposed resist film.

11. A compound represented by the following formula (1-1). (In formula (1-1), M ＋ is, S ＋ Or I ＋ n is an integer between 1 and m, inclusive. ＋ S ＋ In that case, m is 3, and M ＋ I ＋ In that case, m is 2. １ This is a group obtained by removing (a+1) hydrogen atoms from a substituted or unsubstituted aromatic ring. When n is 2 or 3, multiple Ar １ They are either the same or different. a is an integer between 1 and 5. R １ is a substituted or unsubstituted hydrocarbon group. When m-n is 2, there are two R １ They are either the same or different. － (This is a carboxylic acid anion.) 12. A polymer having a structural unit represented by the following formula (IV-1) or (IV-2). (In formulas (IV-1) and (IV-2), R ５ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ The bond is a single bond or an *-COO- bond. * is R ５ This shows the bonding site with the carbon atom to which it is bonded. A ＋ represents the cation portion in formula (1) above. In formula (IV-1), Ar ３ R is a group obtained by removing two hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 20 members. In formula (IV-2), R ６ and R ７ Each of these is independently a hydrogen atom, a fluoro group, a C1-C10 alkyl group, or a C1-C10 monovalent fluorinated alkyl group. １ n is an integer between 1 and 10. １ If there are two or more, multiple R ６ They are either identical or different from each other, and multiple R ７ They are either identical or different from each other. ８ and R ９ Each of these is independently a fluoro group or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. ２ n is an integer between 1 and 10. ２ If there are two or more, multiple R ８ They are either identical or different from each other, and multiple R ９ They are either identical or different from one another.

13. A monomer represented by the following formula (iv-1) or (iv-2). (In formula (iv-1) and (iv-2), R ５ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L ２ is a single bond or *-COO-. * indicates the bonding site with the carbon atom to which R ５ is bonded. A ＋ represents the cationic part in the above formula (1). In formula (iv-1), Ar ３ is a group obtained by removing two hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 20 ring members. In formula (iv-2), R ６ and R ７ are each independently a hydrogen atom, a fluoro group, an alkyl group having 1 to 10 carbon atoms or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. n １ is an integer of 1 to 10. When n １ is 2 or more, a plurality of R ６ are the same as or different from each other, and a plurality of R ７ are the same as or different from each other. R ８ and R ９ are each independently a fluoro group or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. n ２ is an integer of 1 to 10. When n ２ is 2 or more, a plurality of R ８ are the same as or different from each other, and a plurality of R ９ are the same as or different from each other.)

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