TW202112845A - Radiation-sensitive resin composition, resist pattern formation method, and radiation-sensitive acid generator - Google Patents

Abstract

Provided are a radiation-sensitive resin composition with which it is possible to form a resist pattern having excellent sensitivity to exposure light and having exceptional LWR performance and resolution, a resist pattern formation method, and a radiation-sensitive acid generator. A radiation-sensitive resin composition that contains a radiation-sensitive acid generator and a polymer having a first structural unit that contains a first acid-dissociable group dissociated by the action of an acid to yield an alkali-soluble group, the radiation-sensitive resin composition being such that the radiation-sensitive acid generator contains a compound having a sulfonate anion and a radiation-sensitive onium cation, and the sulfonate anion has a second acid-dissociable group that dissociates by the action of a (thio)acetal structure, a carbonyloxy group, and an acid to yield a carboxy group.

Description

Radiation-sensitive resin composition, resist pattern forming method, and radiation-sensitive acid generator

The invention relates to a radiation-sensitive resin composition, a method for forming a resist pattern, and a radiation-sensitive acid generator.

The radiation-sensitive resin composition used in microfabrication by lithography is made of ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm) and other extreme ultraviolet and extreme ultraviolet (wavelength 248 nm). , EUV) (wavelength 13.5 nm) and other electromagnetic waves, electron beams and other charged particle beams and other radioactive rays produce acid in the exposed part, and the exposed part and the non-exposed part react to the developer by the chemical reaction using the acid as a catalyst. The dissolving speed of the film is different, thereby forming a resist pattern on the substrate.

For the radiation-sensitive resin composition, in addition to good sensitivity to exposure light such as extreme ultraviolet rays and electron beams, it also requires Line Width Roughness (LWR) performance and resolution that show the uniformity of the line width. Excellent.

In response to these requirements, the types and molecular structures of polymers, acid generators, and other components used in the radiation-sensitive resin composition have been studied, and their combinations have also been studied in detail (see Japanese Patent Laid-Open) 2010-134279, Japanese Patent Laid-Open No. 2014-224984, and Japanese Patent Laid-Open No. 2016-047815). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-134279 [Patent Document 2] Japanese Patent Laid-Open No. 2014-224984 [Patent Document 3] Japanese Patent Laid-Open No. 2016-047815

[The problem to be solved by the invention] In the current situation where the miniaturization of the resist pattern has progressed to a level below the line width of 40 nm, the required level of the performance has further increased, and the conventional radiation-sensitive resin composition cannot meet the requirements.

The present invention has been completed based on the above-mentioned circumstances, and its object is to provide a radiation-sensitive resin composition and resist that can form a resist pattern with good sensitivity to exposure light and excellent LWR performance and resolution. Pattern formation method and radiation-sensitive acid generator. [Means to solve the problem]

The invention completed to solve the above-mentioned problem is a radiation-sensitive resin composition containing: a polymer having a first structural unit including a first acid-dissociable group that is dissociated by the action of an acid and provides an alkali-soluble group (hereinafter , Also known as "[A] polymer"); and a radiation-sensitive acid generator (hereinafter, also referred to as "[B] acid generator"), the radiation-sensitive acid generator includes a sulfonate anion A compound with a radioactive onium cation, the sulfonate anion has a (sulfur) acetal structure, a carbonyloxy group, and a second acid dissociable group that dissociates by the action of an acid and provides a carboxyl group.

Another invention completed to solve the problem is a method of forming a resist pattern, including: directly or indirectly applying the radiation-sensitive resin composition to a substrate; The step of exposing the formed resist film; and the step of developing the exposed resist film.

Another invention completed to solve the problem is a radiation-sensitive acid generator ([B] acid generator) containing a compound having a sulfonate anion and a radiation-sensitive onium cation, and the radiation-sensitive acid generates The sulfonate anion in the agent has a (sulfur) acetal structure, a carbonyloxy group, and an acid dissociable group that dissociates by the action of an acid and provides a carboxyl group. [Effects of the invention]

According to the radiation-sensitive resin composition and the resist pattern forming method of the present invention, it is possible to form a resist pattern with good sensitivity to exposure light and excellent LWR performance and resolution. The radiation-sensitive acid generator of the present invention can be preferably used as a component of the radiation-sensitive resin composition. Therefore, these can be preferably used in the processing process of semiconductor devices that are expected to be further miniaturized in the future.

＜Radiation-sensitive resin composition＞ This radiation-sensitive resin composition contains [A] a polymer and [B] an acid generator. This radiation-sensitive resin composition usually contains an organic solvent (hereinafter, also referred to as "[D] organic solvent"). The radiation-sensitive resin composition may also contain an acid diffusion control body (hereinafter, also referred to as "[C] acid diffusion control body") as a preferable component. This radiation sensitive resin composition may contain other arbitrary components within the range which does not impair the effect of this invention.

By containing the [A] polymer and [B] acid generator, the radiation-sensitive resin composition can form a resist pattern with good sensitivity to exposure light and excellent LWR performance and resolution. Although the reason why the radiation-sensitive resin composition includes the structure and exerts the effect is not necessarily clear, it can be estimated as follows, for example. That is, when the [B] acid generator contained in the radiation-sensitive resin composition contains a sulfonate anion having a specific structure, the dissolution rate of the exposure part with respect to the developer is improved. As a result, it is considered that this radiation-sensitive resin composition can form a resist pattern that has good sensitivity to exposure light and is excellent in LWR performance and resolution.

Hereinafter, each component contained in this radiation sensitive resin composition is demonstrated.

＜[A] Polymer＞ [A] The polymer has a structural unit (hereinafter, also called "Structural Unit (I)").

[A] The polymer preferably has a structural unit containing a phenolic hydroxyl group in addition to the structural unit (I) (hereinafter, also referred to as "structural unit (II)"). [A] The polymer may further have structural units other than the structural unit (I) and the structural unit (II). The radiation-sensitive resin composition may contain one or two or more [A] polymers.

Hereinafter, each structural unit contained in the [A] polymer will be described.

[Structural unit (I)] The structural unit (I) is a structural unit including an acid-dissociable group (a) that is dissociated by the action of an acid and provides an alkali-soluble group. In this specification, the "alkali-soluble group" refers to a carboxyl group or a hydroxyl group, and the "acid-dissociable group (a)" refers to a group that replaces the hydrogen atom of the alkali-soluble group, and is dissociated and provided by the action of an acid The base of the alkali-soluble base. The acid-dissociable group (a) is dissociated by the action of the acid generated from the [B] acid generator by exposure to produce an alkali-soluble group, and the solubility of the [A] polymer in the exposed part to the developer changes. , Thereby forming a resist pattern.

As the structural unit (I), for example, the structural unit represented by the following formula (I-1A) (hereinafter, also referred to as "structural unit (I-1A)"), the structural unit represented by the following formula (I-1B) The structural unit represented (hereinafter also referred to as "structural unit (I-1B)"), the structural unit represented by the following formula (I-1C) (hereinafter also referred to as "structural unit (I-1C)") , The structural unit represented by the following formula (I-2A) (hereinafter also referred to as "structural unit (I-2A)"), the structural unit represented by the following formula (I-2B) (hereinafter also referred to as "Structural Unit (I-2B)") and so on. ^{In addition, the acid-dissociable group (a) is -C(R X} )(R ^Y )(R ^Z ) bonded to the etheric oxygen atom of the carbonyloxy group in the following formula (I-1A), for example.

[化1]

In the formula (I-1A), formula (I-1B), formula (I-1C), formula (I-2A) and formula (I-2B), R ^T is a hydrogen atom, a fluorine atom, a methyl group or Trifluoromethyl.

In the formulas (I-1A) and (I-1B), R ^X is a monovalent hydrocarbon group having 1 to 20 carbons. R ^Y and R ^Z are each independently a monovalent hydrocarbon group with 1 to 20 carbons, or a saturated alicyclic structure with 3 to 20 ring members formed by combining these groups with the carbon atoms to which they are bonded a part of.

In the formula (I-1C), R ^B , R ^C and R ^E are each independently a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. R ^A and R ^D are each independently a monovalent hydrocarbon group having 1 to 20 carbons, or an unsaturated carbon chain having 4 to 20 ring members formed by combining these groups with each other and the unsaturated carbon chain to which they are bonded. Part of the alicyclic structure.

In the formula (I-2A) and formula (I-2B), R ^U and R ^V are each independently a hydrogen atom or a monovalent hydrocarbon group having ^{1 to 20 carbons, and R W} is a monovalent hydrocarbon group having 1 to 20 carbons. Hydrocarbyl group, or R ^U and R ^V are bonded to each other and form part of an alicyclic structure with 3 to 20 ring members together with the bonded carbon atoms, or R ^U and R ^W are bonded to each other to ^{form a part of R U} The carbon atom to be bonded and ^{the oxygen atom to which R W} is bonded together constitute a part of an aliphatic heterocyclic structure having 5 to 20 ring members.

The "hydrocarbon group" includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The "hydrocarbon group" may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The "chain hydrocarbon group" refers to a hydrocarbon group that does not contain a cyclic structure but only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. The "alicyclic hydrocarbon group" refers to a hydrocarbon group containing only an alicyclic structure as a ring structure, and not an aromatic ring structure, and includes both a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic hydrocarbon group. However, it is not necessary to include only an alicyclic structure, and a chain structure may be included in a part thereof. The "aromatic hydrocarbon group" refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to include only an aromatic ring structure, and a chain structure or an alicyclic structure may be included in a part thereof.

As the monovalent hydrocarbon group having 1 to 20 carbon atoms, ^{R X, R Y, R Z} , R A, R B, R C, R D, R E, R U, R V and R ^W represented, for example, include: A monovalent chain hydrocarbon group having 1 to 20 carbons, a monovalent alicyclic hydrocarbon group having 3 to 20 carbons, a monovalent aromatic hydrocarbon group having 6 to 20 carbons, and the like.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include: Alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, isobutyl, tertiary butyl, etc.; Vinyl, propenyl, butenyl and other alkenyl groups; Alkynyl groups such as ethynyl, propynyl, butynyl, etc.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include: Alicyclic saturated hydrocarbon groups such as cyclopentyl, cyclohexyl, norbornyl, adamantyl, tricyclodecyl, tetracyclododecyl, etc.; Alicyclic unsaturated hydrocarbon groups such as cyclopentenyl, cyclohexenyl, norbornenyl, tricyclodecenyl, tetracyclododecenyl, etc.

As the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, for example: Phenyl, tolyl, xylyl, naphthyl, anthryl and other aryl groups; Aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl.

Examples of saturated alicyclic structures with 3 to 20 ring members formed by R ^Y and R ^Z combined with the carbon atoms to which they are bonded include: cyclopropane structure, cyclobutane structure, and cyclopentane structure , Cyclohexane structure and other monocyclic saturated alicyclic structures; norbornane structure, adamantane structure and other polycyclic saturated alicyclic structures.

Examples of the alicyclic structure having 3 to 20 ring members formed by R ^U and R ^V combined with the carbon atoms to which they are bonded include: cyclopropane structure, cyclobutane structure, cyclopentane structure, Monocyclic saturated alicyclic structures such as cyclohexane structure; polycyclic saturated alicyclic structures such as norbornane structure and adamantane structure; cyclopropene structure, cyclobutene structure, cyclopentene structure, cyclohexene structure, etc. The unsaturated alicyclic structure of the ring; the polycyclic unsaturated alicyclic structure such as norbornene structure, etc.

As R ^A R ^D and bonded to each other and constitute together with the unsaturated carbon chain are bonded to the plurality of number of ring membered unsaturated alicyclic structure having 4 to 20, for example, include: Structure cyclobutene, cyclopentene structure, Monocyclic unsaturated alicyclic structures such as cyclohexene structure; polycyclic unsaturated alicyclic structures such as norbornene structure, etc.

Examples of an aliphatic heterocyclic structure with 5 to 20 ring members formed by R ^U and R ^W bonded together with the oxygen atom ^{to which R U is bonded and the carbon atom to which R W is bonded include:} Saturated oxygen-containing heterocyclic structures such as butane structure, oxolane structure, and oxane structure; unsaturated oxygen-containing heterocyclic structures such as oxetene structure, oxolene structure, and oxolene structure Heterocyclic structure and so on.

As R ^T , a hydrogen atom or a methyl group is preferable from the viewpoint of providing the copolymerizability of the monomer of the structural unit (I).

R ^{X is} preferably a chain hydrocarbon group or an aromatic hydrocarbon group, more preferably an alkyl group or an aryl group, and still more preferably a methyl group, an ethyl group, an isopropyl group, a tertiary butyl group, or a phenyl group.

R ^Y and R ^{Z are} preferably a part of a saturated alicyclic structure having 3 to 20 ring members, which is combined with each other to form a carbon atom. As the alicyclic structure, a monocyclic saturated alicyclic structure is preferable, and a cyclopentane structure is more preferable.

As R ^B and R ^C , a hydrogen atom is preferable.

As R ^E , a hydrogen atom or a chain hydrocarbon group is preferable, a hydrogen atom or an alkyl group is more preferable, and a hydrogen atom or a methyl group is more preferable.

R ^A and R ^{D are} preferably a part of an unsaturated alicyclic structure formed by these mutually bonded carbon atoms together with the bonded carbon atoms. The unsaturated alicyclic structure is preferably a monocyclic unsaturated alicyclic structure, more preferably a cyclopentene structure or a cyclohexene structure.

The structural unit (I) is preferably a structural unit (I-1A) or a structural unit (I-1C).

The structural unit (I-1A) is preferably a structural unit represented by the following formula (I-1A-1) to formula (I-1A-5) (hereinafter, also referred to as "structural unit (I-1A- 1) ~ Structural unit (I-1A-5)”).

[化2]

In the formulas (I-1A-1) to (I-1A-5), R ^T has the same meaning as the formula (I-1A).

The structural unit (I-1C) is preferably a structural unit represented by the following formula (I-1C-1) to formula (I-1C-2) (hereinafter, also referred to as "structural unit (I-1C- 1) ~ Structural unit (I-1C-2)”).

[化3]

In the formula (I-1C-1) and the formula (I-1C-2), R ^T has the same meaning as the formula (I-1C).

The lower limit of the content ratio of the structural unit (I) is preferably 5 mol%, more preferably 10 mol%, and still more preferably 15 mol% with respect to all the structural units constituting the [A] polymer. Preferably, it is 20 mol%. The upper limit of the content ratio is preferably 90 mol%, more preferably 80 mol%, further preferably 70 mol%, particularly preferably 65 mol%. By setting the content ratio of the structural unit (I) in the above range, the sensitivity of the radiation-sensitive resin composition to exposure light, LWR performance, and resolution can be further improved.

[Structural unit (II)] The structural unit (II) is a structural unit containing a phenolic hydroxyl group. The "phenolic hydroxyl group" is not limited to the hydroxyl group directly bonded to the benzene ring, but refers to all the hydroxyl groups directly bonded to the aromatic ring. In the case of KrF exposure, EUV exposure or electron beam exposure, the [A] polymer has the structural unit (II), which can further improve the sensitivity of the radiation-sensitive resin composition to exposure light.

As the structural unit (II), for example, structural units represented by the following formula (II-1) to formula (II-15) (hereinafter, also referred to as "structural unit (II-1) to structural unit (II- 15)”) etc.

[化4]

In the formulas (II-1) to (II-15), R ^P is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

As R ^P , from the viewpoint of providing the copolymerizability of the monomer of the structural unit (II), a hydrogen atom or a methyl group is preferable, and a hydrogen atom is more preferable.

As the structural unit (II), the structural unit (II-1) or the structural unit (II-2) is preferred.

In the case where the [A] polymer has the structural unit (II), the lower limit of the content of the structural unit (II) is preferably 10 mol% relative to all the structural units constituting the [A] polymer, and more It is preferably 20 mol%, and further preferably 25 mol%. The upper limit of the content ratio is preferably 80 mol%, more preferably 60 mol%, and still more preferably 50 mol%. By setting the content ratio of the structural unit (II) in the above range, the sensitivity of the radiation-sensitive resin composition to exposure light, LWR performance, and resolution can be further improved.

[Other structural units] Examples of other structural units include structural units containing alcoholic hydroxyl groups (hereinafter also referred to as "structural unit (III)" or "third structural unit"), lactone structures, cyclic carbonate structures, and sulfonic acid groups. A structural unit of a lactone structure or a combination of these structures, etc.

(Structural unit (III)) As a structural unit (III), the structural unit etc. which are represented by the following formula, for example are mentioned. [A] The polymer further has the structural unit (III), which can further improve the LWR performance and resolution.

[化5]

In the formula, R ^L2 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

In the case where the [A] polymer has other structural units, as the upper limit of the content ratio of the other structural units, relative to all the structural units constituting the [A] polymer, it is preferably 30 mol%, more preferably 15 mol%. ear%.

As the lower limit of the content of the [A] polymer in the radiation-sensitive resin composition, relative to all components other than the [D] organic solvent of the radiation-sensitive resin composition, it is preferably 50% by mass, more preferably It is 60% by mass, and more preferably 70% by mass. The upper limit of the content ratio is preferably 99% by mass, and more preferably 95% by mass.

[A] The lower limit of the polystyrene-converted weight average molecular weight (Mw) obtained by gel permeation chromatography (GPC) as the polymer is preferably 1,000, more preferably 3,000, and still more preferably 4,000, particularly preferably 5,000. The upper limit of the Mw is preferably 50,000, more preferably 30,000, still more preferably 20,000, and particularly preferably 10,000. By setting the Mw of the polymer [A] in the above range, the coating property of the radiation-sensitive resin composition can be improved.

[A] The upper limit of the ratio of the Mw of the polymer to the polystyrene-converted number average molecular weight (Mn) obtained by GPC (hereinafter also referred to as "dispersion degree" or "Mw/Mn") is preferable It is 5, more preferably 3, further preferably 2, and particularly preferably 1.8. As the lower limit of the ratio, it is usually 1, and preferably 1.1.

The Mw and Mn of the polymer in this specification are values measured using gel permeation chromatography (GPC) based on the following conditions. GPC string: two "G2000HXL", one "G3000HXL" and one "G4000HXL" from Tosoh (stock) Column temperature: 40℃ Dissolution solvent: Tetrahydrofuran (Fuji Film Wako Pure Chemical Industries, Ltd.) Flow rate: 1.0 mL/min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: Differential refractometer Standard material: monodisperse polystyrene

＜[B] Acid generator＞ [B] The acid generator contains a sulfonate anion and a radiation-sensitive onium cation, and the sulfonate anion has a (sulfur) acetal structure, a carbonyloxy group, and a second dissociated by the action of an acid to provide a carboxyl group. A compound of an acid dissociable group (hereinafter, also referred to as "acid dissociable group (b)") (hereinafter, also referred to as "compound (B)"). The compound (B) is a substance that generates acid by irradiation with radiation. Examples of radiation include electromagnetic waves such as visible rays, ultraviolet rays, extreme ultraviolet rays, extreme ultraviolet (EUV), X-rays, and gamma rays, and charged particle beams such as electron beams and alpha rays. Utilizing the acid generated from the compound (B) by irradiation with radiation, the acid dissociable group (a) contained in the structural unit (I) of the polymer is dissociated and an alkali-soluble group is generated. [A] The solubility of the polymer in the developer is changed, thereby forming a resist pattern. The radiation-sensitive resin composition may contain one or two or more [B] acid generators.

In the compound (B), the acid generated from the compound (B) by radiation (exposure) is used, and the acid dissociable group (b) of the compound (B) is dissociated to generate a carboxyl group, thereby interacting with the exposed part The difference (dissolution contrast) in the solubility of the resist film with respect to the developer between the non-exposed portions further increases. Therefore, it is considered that this radiation-sensitive resin composition can form a resist pattern excellent in LWR performance and resolution.

Hereinafter, each structure possessed by the compound (B) will be described.

[Sulfonate Anion] The sulfonate anion has a (sulfur) acetal structure, a carbonyloxy group, and an acid dissociable group (b) that is dissociated by the action of an acid and provides an alkali-soluble group. The sulfonate anion preferably further has an alicyclic structure other than the acid dissociable group (b) (hereinafter, also referred to as "alicyclic structure (c)"). It is preferable that the sulfonate anion further has a partial structure represented by the following formula (3) described later (hereinafter, also referred to as "partial structure (d)"). In addition, the sulfonate anion may have a structure other than the above-mentioned structure as necessary.

Hereinafter, each structure possessed by the sulfonate anion will be described.

((Sulfur)acetal structure) The "(sulfur)acetal structure" in this specification includes both the "acetal structure" and the "thioacetal structure". In addition, "(sulfur) acetal structure" includes both "chain (sulfur) acetal structure" and "cyclic (sulfur) acetal structure". Furthermore, the "thioacetal structure" includes both the "monothioacetal structure" and the "dithioacetal structure".

As the (sulfur) acetal structure, if focusing on the structure, it is preferably a cyclic (sulfur) acetal structure, and if focusing on the structural atoms, it is preferably an acetal structure or a monothioacetal structure. When the (sulfur) acetal structure is the above-mentioned structure, the LWR performance and resolution of the radiation-sensitive resin composition can be further improved. That is, the (sulfur) acetal structure is preferably a cyclic (sulfur) acetal structure, more preferably a cyclic acetal structure or a cyclic monothioacetal structure, and still more preferably a cyclic acetal structure.

As a cyclic (sulfur) acetal structure, the structure represented by following formula (1) is mentioned, for example.

[化6]

In the formula (1), X ¹ and X ² are each independently -O- or -S-. R ¹ is a (n+2) valent hydrocarbon group having 1 to 10 carbon atoms. n is an integer of 0-2. * Represents a bonding site with a part other than the structure represented by the formula (1) in the sulfonate anion.

Furthermore, regarding the classification of the cyclic (sulfur) acetal structure, in the formula (1), the case where X ¹ and X ² are both -O- is a "cyclic acetal structure", and X ¹ and When ^{at least one of X 2} is -S-, it is a "cyclic thioacetal structure". Furthermore, ^{a case where one of X 1} and X ² is -O- and the other is -S- is a "cyclic monothioacetal structure", ^{and a case where both X 1} and X ² are -S- is a "cyclic Shaped dithioacetal structure".

As X ¹ and X ² , it is preferable that at least one ^{of X 1} and X ^{2 is -O-.} In this case, the sensitivity, LWR performance, and resolution of the radiation-sensitive resin composition to exposure light can be further improved.

Examples of the (n+2) valent hydrocarbon group having 1 to 10 carbon atoms represented by R ¹ include groups obtained by removing (n+2) hydrogen atoms from alkanes such as methane, ethane, n-propane, and n-butane. . R ^{1 is} preferably a hydrocarbon group having a carbon number of 5 or 7 in the cyclic (sulfur) acetal structure represented by the formula (1). That is, as R ¹ , a group obtained by removing (n+2) hydrogen atoms from ethane or n-butane is preferable. In addition, the "number of ring members of the cyclic (sulfur) acetal structure" refers to the number of atoms of the ring structure constituting the cyclic (sulfur) acetal structure.

(Carbonyloxy and acid dissociable group (b)) In the sulfonate anion, the acid dissociable group (b) and the etheric oxygen atom of the carbonyloxy group (hereinafter sometimes described as "-C(=O)O-" or simply "-COO-") (Oxygen atom bonded to carbon atom by a single bond) Bonding. The acid dissociable group (b) is dissociated from the carbonyloxy group by the action of an acid, thereby generating a carboxyl group.

The acid dissociable group (b) is a group that is dissociated by the action of an acid and provides a carboxyl group. In more detail, the "acid dissociable group (b)" is a group that substitutes a hydrogen atom of a carboxyl group, and is a group that dissociates by the action of an acid to provide a carboxyl group.

As an acid dissociable group (b), the group represented by following formula (2-1), the group represented by following formula (2-2), etc. are mentioned, for example.

[化7]

In the formulas (2-1) and (2-2), ** represents the bonding site with the etheric oxygen atom of the carbonyloxy group in the sulfonate anion.

In the formula (2-1), R ² is a monovalent hydrocarbon group having 1 to 20 carbon atoms or a group containing the (sulfur) acetal structure. R ³ and R ⁴ are each independently a monovalent hydrocarbon group with 1 to 20 carbons, or a saturated alicyclic structure with 3 to 20 ring members formed by combining these groups with the carbon atoms to which they are bonded a part of.

In the formula (2-2), R ⁶ , R ⁷ and R ⁹ are each independently a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. R ⁵ and R ⁸ are each independently a monovalent hydrocarbon group with 1 to 20 carbons, or an unsaturated carbon chain with 4 to 20 ring members formed by combining these groups with each other and the unsaturated carbon chain to which they are bonded. Part of the alicyclic structure.

Regarding the monovalent hydrocarbon groups having 1 to 20 carbons represented ^{as R 2} , R ³ and R ⁴ , for example, the carbon numbers represented by ^{R X} , R ^Y and R ^{Z as the formula (I-1A)} The monovalent hydrocarbon group of 1-20 is the same as the exemplified group.

Examples of the saturated alicyclic structure of 3 to 20 ring members formed by R ³ and R ^{4 combined with the carbon atoms to which they are bonded include R Y} and R Y as the formula (I-1A). The saturated alicyclic structure constituted by R ^Z has the same structure as the exemplified structure.

Examples of the monovalent hydrocarbon group having 1 to 20 carbons represented by R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ^{9 include R A} , R ^B , and R ^{C as the formula (I-1C).} The monovalent hydrocarbon groups having 1 to 20 carbons represented by ^{R D} and R ^{E are the same groups as those exemplified.}

When R ² is a monovalent hydrocarbon group having 1 to 20 carbon atoms, R ^{2 is} preferably a chain hydrocarbon group, more preferably an alkyl group, and still more preferably a methyl group or an ethyl group.

When R ² is a group containing the (sulfur) acetal structure, R ^{2 is} preferably a group containing a cyclic (sulfur) acetal structure, and more preferably contains the group represented by the formula (1) The group of the structure of is more preferably a group including the structure represented by the formula (1) and the alicyclic structure (c) described later.

As R ² , a monovalent hydrocarbon group having 1 to 20 carbon atoms is preferred. When R ² is a monovalent hydrocarbon group with 1 to 20 carbon atoms, the sensitivity to exposure light, LWR performance, and resolution can be further improved.

When R ³ and R ⁴ are a monovalent hydrocarbon group having 1 to 20 carbon atoms, R ³ and R ^{4 are} preferably a chain hydrocarbon group, more preferably an alkyl group, and still more preferably a methyl group or an ethyl group.

In the case where R ³ and R ⁴ are part of an alicyclic structure having 3 to 20 ring members formed together with these bonded carbon atoms, the alicyclic structure is preferably The saturated alicyclic structure is more preferably a monocyclic saturated alicyclic structure, and even more preferably a cyclopentane structure.

As R ⁶ and R ⁷ , a hydrogen atom is preferred.

As R ⁹ , a chain hydrocarbon group is preferable, an alkyl group is more preferable, and a methyl group is still more preferable.

R ⁵ and R ^{8 are} preferably a part of an unsaturated alicyclic structure having 4 to 20 ring members, which is combined with the unsaturated carbon chains to be bonded to each other. The unsaturated alicyclic structure is preferably a monocyclic unsaturated alicyclic structure, and more preferably a cyclohexene structure.

(Alicyclic structure (c)) The sulfonate anion preferably further has an alicyclic structure (alicyclic structure (c)) other than the acid dissociable group (b). When the sulfonate anion further has an alicyclic structure (c), the diffusion of the acid generated from the compound (B) can be moderately suppressed, and as a result, the resolution and LWR performance can be further improved.

As the alicyclic structure (c), for example, the same structure as the structure exemplified as the alicyclic structure composed of ^{R U} and R ^{V of the formula (I-2A) can be cited.}

As the alicyclic structure (c), a saturated alicyclic structure is preferable, and a cyclohexane structure, a norbornane structure, or an adamantane structure is more preferable.

In addition, the alicyclic structure (c) preferably shares a carbon atom or a part of the carbon chain with the (sulfur) acetal structure. For example, when the alicyclic structure (c) is a norbornane structure, a part of the carbon chains constituting the norbornane structure and a part of the carbon chains constituting the (sulfur) acetal structure are common. For example, when the alicyclic structure (c) is a cyclohexane structure or an adamantane structure, one carbon atom constituting the cyclohexane structure or adamantane structure and one carbon atom constituting the (sulfur) acetal structure are common State and so on.

(Partial structure (d)) The sulfonate anion preferably further has a partial structure (partial structure (d)) represented by the following formula (3). When the sulfonate anion further has a partial structure (d), the acid generated from the compound (B) becomes a stronger acid, which can further promote the acid dissociable group contained in the structural unit (I) of the polymer [A] ( a) dissociation.

[化8]

In the formula (3), R ¹⁰ and R ¹¹ are each independently a hydrogen atom, a fluorine atom, a C 1-20 monovalent hydrocarbon group or a C 1-20 monovalent fluorinated hydrocarbon group. Among them, ^{at least one of R 10} and R ¹¹ is a fluorine atom or a C 1-20 monovalent fluorinated hydrocarbon group. m is an integer of 1-10. When m is 2 or more, a plurality of R ¹⁰ are the same or different from each other, and a plurality of R ¹¹ are the same or different from each other. *** represents a bonding site with a part other than the structure represented by formula (3) in the sulfonate anion.

Examples of the monovalent hydrocarbon group having 1 to 20 carbons represented by R ¹⁰ and R ¹¹ include those with 1 to 20 carbons represented by ^{R X} , R ^Y and R ^{Z of the formula (I-1A).} The monovalent hydrocarbon group is the same as the exemplified group and the like.

Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbons represented by R ¹⁰ and R ^{11 include those having 1 to 20 carbons represented by R X} , R ^Y and R ^Z of the above formula (I-1A) Examples of monovalent hydrocarbon groups include groups in which at least one hydrogen atom is substituted with a fluorine atom.

The sulfonate anion has only the above-mentioned structures. In the chemical structure of the sulfonate anion, the position and orientation of the (sulfur) acetal structure, carbonyloxy group, and acid dissociable group (b) are not particularly limited. . The sulfonate anion preferably has an acid dissociable group (b) at the terminal. The sulfonate anion has an acid dissociable group (b) at the end, which can further improve the sensitivity to exposure light, LWR performance and resolution. In addition, when the (sulfur) acetal structure is the cyclic (sulfur) acetal structure represented by the formula (1), it is preferable that R ¹ is in the direction of the SO ^{3-side. When R 1 in} the above formula (1) is oriented toward the SO ^3- side, the sensitivity to exposure light, LWR performance, and resolution can be further improved.

As a sulfonate anion, the structure represented by following formula (4-1) or the structure represented by following formula (4-2), etc. are mentioned, for example.

[化9]

In the above formula (4-1) and formula (4-2), X is a group containing a (thio)acetal structure. Y is an acid dissociable group (b). L ¹ and L ² are each independently a single bond or a divalent linking group.

The ^{divalent linking group represented by L 1} and L ² includes, for example, a divalent heteroatom-containing group, a divalent hydrocarbon group, and a group including the divalent heteroatom-containing group between carbon and carbon of the hydrocarbon group. Group (hereinafter, also referred to as "group (α)"), a group in which part or all of the hydrogen atoms of the hydrocarbon group are substituted with a monovalent heteroatom-containing group (hereinafter, also referred to as "group (β)") A group in which part or all of the hydrogen atoms of the group (α) are substituted with a monovalent heteroatom-containing group (hereinafter, also referred to as "group (γ)"), etc.

As the divalent heteroatom-containing group, for example, -CO-, -CS-, -NH-, -O-, -S-, and a combination of these groups, etc. may be mentioned.

Examples of the monovalent heteroatom-containing group include a hydroxyl group, a mercapto group, a cyano group, a nitro group, and a halogen atom.

As the divalent hydrocarbon group, for example, a group obtained by removing one hydrogen atom from the group exemplified as the monovalent hydrocarbon group having 1 to 20 carbons represented ^{by R X} , R ^Y and R ^{Z of the above formula (I-1A)} Wait.

When the sulfonate anion further has an alicyclic structure (c), the alicyclic structure (c) is contained in the ^{divalent linking group represented by L 1} or L ² , or the (sulfur) acetal structure and the alicyclic structure (C) Sharing a carbon atom or part of a carbon chain.

L ^{2 is} preferably a structure including -(CR ¹⁰ R ¹¹ ) _m -in the formula (3).

As the sulfonate anion, the structure represented by the above formula (4-1) is preferred. When the sulfonate anion is the formula (4-1), the sensitivity to exposure light, LWR performance, and resolution can be further improved.

Examples of the structure represented by the formula (4-1) include the structure represented by the following formula (4-1-1) or the structure represented by the formula (4-1-2).

[化10]

In the formula (4-1-1) and the formula (4-1-2), Y, L ¹ and L ² have the same meaning as the formula (4-1). R ¹ , X ¹ and X ² have the same meaning as in the above formula (1).

In the formula (4-1-1), L ¹¹ is a divalent linking group, L ¹² is a hydrogen atom or a monovalent organic group having 1 to 20 carbons, or L ¹¹ and L ¹² are mutually bonded and combined with these The bonded carbon atoms together constitute part of a ring structure with 3 to 20 ring members.

In the formula (4-1-2), L ²¹ is a divalent linking group, L ²² is a hydrogen atom or a monovalent organic group having 1 to 20 carbons, or L ²¹ and L ²² are bonded to each other and are The bonded carbon atoms together constitute part of a ring structure with 3 to 20 ring members.

The so-called "organic group" refers to a group containing at least one carbon atom.

Examples of the divalent linking group represented by L ¹¹ and L ²¹ include the same groups as those exemplified as the divalent linking group represented by ^{L 1} and L ^{2 of the formula (4-1).}

Examples of the monovalent organic group having 1 to 20 carbons represented by L ¹² and L ²² include: a monovalent hydrocarbon group having 1 to 20 carbons, and a divalent heteroatom-containing group between carbon and carbon of the hydrocarbon group. The group (hereinafter, also referred to as "group (α')"), a group in which part or all of the hydrogen atoms of the hydrocarbon group are substituted with a monovalent heteroatom-containing group (hereinafter, also referred to as "group (β')"')”), a group in which part or all of the hydrogen atoms of the group (α') are substituted with a monovalent heteroatom-containing group (hereinafter, also referred to as "group (γ')"), and the like.

Examples of the ring structure having 3 to 20 ring members formed by L ¹¹ and L ¹² or L ²¹ and L ²² combined with each other and the carbon atoms to which they are bonded include, for example, the formula (I-1A) The alicyclic structure composed of R ^Y and R ^Z is the same structure as the exemplified structure.

The structure represented by the formula (4-1) is preferably the structure represented by the formula (4-1-1). When the sulfonate anion is the formula (4-1-1), the sensitivity to exposure light, LWR performance, and resolution can be further improved.

[Radio-sensitive onium cation] Examples of radiation-sensitive onium cations include monovalent cations represented by the following formula (ra) (hereinafter also referred to as "cations (ra)") and monovalent cations represented by the following formula (rb) ( Hereinafter, it is also referred to as "cation (rb)"), a monovalent cation represented by the following formula (rc) (hereinafter also referred to as "cation (rc)"), and the like.

[化11]

In the formula (ra), b1 is an integer of 0-4. When b1 is 1, R ^B1 is a monovalent organic group having 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom. When b1 is 2 or more, a plurality of R ^B1 are the same or different from each other, and are a monovalent organic group having 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom, or these groups are bonded to each other and are combined with these groups. The bonded carbon chains together constitute a part of a ring structure with 4 to 20 ring members. b2 is an integer of 0-4. When b2 is 1, R ^B2 is a monovalent organic group having 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom. When b2 is 2 or more, a plurality of R ^B2 are the same or different from each other and are a monovalent organic group having 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom, or these groups are bonded to each other and are combined with these groups. The bonded carbon chains together constitute a part of a ring structure with 4 to 20 ring members. R ^B3 and R ^B4 are each independently a hydrogen atom, a monovalent organic group having 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom, or R ^B3 and R ^B4 are bonded to each other to represent a single bond. b3 is an integer of 0-11. When b3 is 1, R ^B5 is a monovalent organic group having 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom. When b3 is 2 or more, a plurality of R ^B5 are the same or different from each other and are a monovalent organic group having 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom, or these groups are bonded to each other and are combined with these groups. The bonded carbon chains together constitute a part of a ring structure with 4 to 20 ring members. n _b1 is an integer of 0-3.

In the formula (rb), b4 is an integer of 0-9. When b4 is 1, R ^B6 is a monovalent organic group having 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom. When b4 is 2 or more, a plurality of R ^B6 are the same or different from each other, and are a monovalent organic group having 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom, or these groups are bonded to each other and are combined with these groups. The bonded carbon chains together constitute a part of a ring structure with 4 to 20 ring members. b5 is an integer of 0-10. When b5 is 1, R ^B7 is a monovalent organic group having 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom. When b5 is 2 or more, multiple R ^B7 are the same or different from each other, and are a monovalent organic group with 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom, or these groups are bonded to each other and are combined with these groups. The bonded carbon atoms or carbon chains together constitute a part of a ring structure with 3 to 20 ring members. n _b3 is an integer of 0-3. R ^B8 is a single bond or a divalent organic group having 1 to 20 carbons. n _b2 is an integer of 0-2.

In the formula (rc), b6 is an integer of 0-5. When b6 is 1, R ^B9 is a monovalent organic group having 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom. When b6 is 2 or more, multiple R ^B9 are the same or different from each other and are a monovalent organic group with 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom, or these groups are bonded to each other and are combined with these groups. The bonded carbon chains together constitute a part of a ring structure with 4 to 20 ring members. b7 is an integer of 0-5. When b7 is 1, R ^B10 is a monovalent organic group having 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom. When b7 is 2 or more, a plurality of R ^B10 are the same or different from each other and are a monovalent organic group with 1 to 20 carbons, a hydroxyl group, a nitro group, or a halogen atom, or these groups are bonded to each other and are combined with these groups. The bonded carbon chains together constitute a part of a ring structure with 4 to 20 ring members.

R ^B1 , R ^B2 , R ^B3 , R ^B4 , R ^B5 , R ^B6 , R ^B7 , R ^B9 and R ^B10 represent monovalent organic groups having 1 to 20 carbon atoms, for example, and as the above-mentioned formula ( The monovalent organic group having 1 to 20 carbon atoms represented ^{by L 12} in 4-1-1) is the same as the exemplified groups.

Examples of the divalent organic group represented by R ^B8 include the removal of one hydrogen atom from the group exemplified as the monovalent organic group having 1 to 20 carbons represented by ^{L 12 in the formula (4-1-1).} After the base and so on.

R ^B1 , R ^B2 and R ^{B5 are} preferably a halogen atom, a hydroxyl group or a monovalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a halogen atom, a hydroxyl group or an alicyclic hydrocarbon group, and still more preferably a halogen atom, a hydroxyl group or a saturated hydrocarbon group. The alicyclic hydrocarbon group of is particularly preferably a fluorine atom, a hydroxyl group or a cyclohexyl group.

R ^B3 and R ^{B4 are} preferably a hydrogen atom or a single bond formed by bonding ^{R B4} and R ^{B5 to each other.}

As b1 and b2, 0-2 are preferable, 0 or 1 are more preferable, and 0 is still more preferable. As b3, 0-4 are preferable, 0-2 is more preferable, and 0 or 1 is still more preferable. As n _b1 , 0 or 1 is preferable.

The radiation-sensitive onium cation is preferably a cation (r-a).

Examples of the cation (ra) include cations represented by the following formulas (ra-1) to (ra-8) (hereinafter also referred to as "cations (ra-1) to cations (ra-8)") .

[化12]

The compound (B) may appropriately combine the sulfonate anion and the radiosensitive onium cation.

The compound (B) is preferably a compound represented by the following formula (B1) to formula (B13) (hereinafter, also referred to as "compound (B1) to compound (B13)"). Furthermore, as an example in which the (sulfur) acetal structure is contained in the acid-dissociable group (b), the compound (B11)-the compound (B13) are mentioned.

[化13]

In the formulas (B1) to (B13), T ⁺ is the radiation-sensitive onium cation.

As the lower limit of the content of the [B] acid generator in the radiation-sensitive resin composition, relative to 100 parts by mass of the [A] polymer, it is preferably 5 parts by mass, more preferably 10 parts by mass, and still more preferably 15 Mass parts. The upper limit of the content is preferably 65 parts by mass, more preferably 60 parts by mass, and still more preferably 55 parts by mass. By setting the content of the [B] acid generator in the above range, the sensitivity to exposure light, LWR performance, and resolution can be further improved.

＜[C] Acid diffusion control body＞ [C] The acid diffusion control body has a function of controlling the diffusion phenomenon in the resist film of acid generated from the [B] acid generator or the like by exposure, and suppressing a poor chemical reaction in the non-exposed portion. In addition, the storage stability of the radiation-sensitive resin composition can be improved, and the resolution can be further improved. Furthermore, it is possible to suppress the line width change of the resist pattern due to the variation of the standing time from exposure to development processing, and it is possible to obtain a radiation-sensitive resin composition having excellent process stability. Examples of the form of the [C] acid diffusion control body contained in the radiation-sensitive resin composition include the form of a low-molecular compound (hereinafter, also referred to as "[C] acid diffusion control agent" as appropriate), as [A ] A form in which a part of a polymer such as a polymer is incorporated, and the form of both of these. The radiation-sensitive resin composition may contain one or two or more [C] acid diffusion controllers.

[C] The acid diffusion control agent includes, for example, a nitrogen atom-containing compound, a photodegradable base that generates light by exposure to light and generates a weak acid, and the like.

Examples of the nitrogen atom-containing compound include amine compounds such as tripentylamine and trioctylamine, amide group-containing compounds such as formamide, N,N-dimethylacetamide, urea, 1, Urea compounds such as 1-dimethylurea, nitrogen-containing heterocyclic compounds such as pyridine, N-(undecylcarbonyloxyethyl)morpholine, N-third pentyloxycarbonyl-4-hydroxypiperidine, etc.

As the photodegradable base, for example, a compound containing an onium cation that is decomposed by exposure and an anion of a weak acid, and the like. The photodegradable base generates an acid in the exposed portion to increase the solubility or insolubility of the [A] polymer in the developing solution, and as a result, the surface roughness of the exposed portion after development is suppressed. On the other hand, in the non-exposed part, it exhibits a high acid capturing function due to anions, functions as a quencher, and captures acid diffused from the exposed part. That is, since only the non-exposed part functions as a quencher, the contrast of the deprotection reaction is improved, and as a result, the resolution can be further improved.

Examples of the onium cations that are decomposed by exposure include those the same as the radiation-sensitive onium cations exemplified in the section of <[B] Acid Generator>.

Examples of the anion of the weak acid include anions represented by the following formulas (C1) to (C4).

[化14]

As the photodegradable base, a compound obtained by appropriately combining the onium cation decomposed by exposure and the anion of the weak acid can be used.

When the radiation-sensitive resin composition contains [C] acid diffusion control agent, the lower limit of the content ratio of [C] acid diffusion control agent is preferably 100 mol% relative to [B] acid generator 1 mol%, more preferably 5 mol%, and still more preferably 10 mol%. The upper limit of the content is preferably 100 mol%, more preferably 50 mol%, and still more preferably 30 mol%. By setting the content ratio of the [C] acid diffusion control agent in the above range, the sensitivity of the resist pattern formed of the radiation-sensitive resin composition to exposure light, LWR performance, and resolution can be further improved.

＜[D]Organic solvent＞ The radiation-sensitive resin composition usually contains [D] an organic solvent. [D] The organic solvent is not particularly limited as long as it can dissolve or disperse at least the [A] polymer and [B] acid generator, and optionally the [C] acid diffusion controller and other optional components. .

[D] The organic solvent includes, for example, alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents. [D] The organic solvent may contain one kind or two or more kinds.

Examples of alcohol solvents include aliphatic monoalcohol solvents having 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol, and alicyclic monoalcohols having 3 to 18 carbon atoms such as cyclohexanol. Solvents, C2-C18 polyol solvents such as 1,2-propylene glycol, C3-C19 polyol partial ether solvents such as propylene glycol-1-monomethyl ether, etc.

Examples of ether solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether, tetrahydrofuran, and tetrahydropyran. Cyclic ether solvents, diphenyl ether, anisole, and other aromatic ring-containing ether solvents.

Examples of ketone solvents include acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, methyl isobutyl ketone, 2-heptanone, and ethyl Chain ketone solvents such as n-butyl ketone, methyl n-hexyl ketone, diisobutyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone And other cyclic ketone solvents, 2,4-pentanedione, acetonylacetone, acetophenone, etc.

Examples of amide-based solvents include cyclic amide-based solvents such as N,N'-dimethylimidazolidone and N-methylpyrrolidone, N-methylmethamide, N,N-di Methylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylacetamide, etc. Amide-based solvents, etc.

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, and polyhydric alcohol carboxylic acid esters such as propylene glycol acetate. Solvents, polyhydric alcohol partial ether carboxylate solvents such as propylene glycol monomethyl ether acetate, polycarboxylic acid diester solvents such as diethyl oxalate, and carbonate-based solvents such as dimethyl carbonate and diethyl carbonate Wait.

Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents having 5 to 12 carbon atoms such as n-pentane and n-hexane, and aromatic hydrocarbon solvents having 6 to 16 carbon atoms such as toluene and xylene.

[D] The organic solvent is preferably an alcohol-based solvent or an ester-based solvent, more preferably a C3-19 polyhydric alcohol partial ether solvent or a polyhydric alcohol partial ether carboxylate solvent, and more preferably propylene glycol-1 -Monomethyl ether or propylene glycol monomethyl ether acetate.

When the radiation-sensitive resin composition contains [D] an organic solvent, the lower limit of the content ratio of [D] organic solvent is preferably 50 mass with respect to all components contained in the radiation-sensitive resin composition %, more preferably 60% by mass, still more preferably 70% by mass, particularly preferably 80% by mass. The upper limit of the content ratio is preferably 99.9% by mass, more preferably 99.5% by mass, and more preferably 99.0% by mass.

＜Other optional ingredients＞ As other optional components, for example, surfactants and the like can be cited. The radiation-sensitive resin composition may each contain one or two or more other optional components.

＜Preparation method of radiation-sensitive resin composition＞ The radiation-sensitive resin composition can be defined by, for example, [A] polymer, [B] acid generator, and optionally containing [C] acid diffusion controller, [D] organic solvent, and other optional components. It is preferably prepared by filtering the obtained mixture with a membrane filter with a pore size of 0.2 μm or less.

The radiation-sensitive resin composition can be used for both positive resist pattern formation using alkaline developer and negative resist pattern formation using organic solvent-containing developer.

This radiation-sensitive resin composition is used for exposure with radiation (exposure light) irradiated in the exposure step of the resist pattern forming method described later. Among the exposure light, extreme ultraviolet (EUV) or electron beams have higher energy, but according to the radiation-sensitive resin composition, even when extreme ultraviolet or electron beams are used as exposure light, the exposure light can be formed. A resist pattern with good sensitivity and excellent LWR performance and resolution. Therefore, the radiation-sensitive resin composition can be particularly preferably used for extreme ultraviolet exposure applications or electron beam exposure applications.

<Method of forming resist pattern> The resist pattern forming method includes a step of directly or indirectly applying the radiation-sensitive resin composition to a substrate (hereinafter, also referred to as "coating step"); The step of exposing the resist film of (hereinafter, also referred to as "exposure step"); and the step of developing the exposed resist film (hereinafter, also referred to as "development step").

According to the resist pattern forming method, the radiation-sensitive resin composition is used in the coating step, whereby a resist having good sensitivity to exposure light and excellent LWR performance and resolution can be formed pattern.

Hereinafter, each step included in the resist pattern forming method will be described.

[Coating Step] In this step, the radiation-sensitive resin composition is directly or indirectly applied to the substrate. Thereby, a resist film is formed. Examples of the substrate include conventionally known ones such as silicon wafers, silicon dioxide, and aluminum-coated wafers. In addition, as a case of indirectly applying the radiation-sensitive resin composition on the substrate, for example, the case where the radiation-sensitive resin composition is applied on an anti-reflection film formed on the substrate. As such an anti-reflection film, for example, an organic or inorganic anti-reflection film disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Application Publication No. 59-93448, etc. can be cited.

As a coating method, spin coating (spin coating), cast coating, roll coating, etc. are mentioned, for example. After coating, in order to volatilize the solvent in the coating film, pre-baking (hereinafter, also referred to as "PB (prebake)") may be performed if necessary. The lower limit of the temperature of PB is preferably 60°C, more preferably 80°C. The upper limit of the temperature is preferably 150°C, more preferably 140°C. The lower limit of the PB time is preferably 5 seconds, more preferably 10 seconds. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds. The lower limit of the average thickness of the formed resist film is preferably 10 nm, and more preferably 20 nm. The upper limit of the average thickness is preferably 1,000 nm, and more preferably 500 nm.

[Exposure Step] In this step, the resist film formed by the coating step is exposed. This exposure is performed by irradiating exposure light through a photomask (water-proof and other liquid immersion medium as the case may be). As the exposure light, depending on the line width of the target pattern, for example, electromagnetic waves such as visible light, ultraviolet, extreme ultraviolet, extreme ultraviolet (EUV), X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays. Among these, it is preferably extreme ultraviolet, EUV or electron beam, more preferably ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV (wavelength 13.5 nm) or electron beam, Furthermore, ArF excimer laser light, EUV or electron beam is more preferable, and EUV or electron beam is particularly preferable.

It is preferable to perform post-exposure bake (hereinafter, also referred to as "PEB (post exposure bake)") after the exposure, to promote the self-exposure by the exposure in the exposed part of the resist film [B] [A] Dissociation of the acid dissociable group possessed by the polymer etc. caused by the acid generated by the acid generator or the like. With this PEB, the difference in solubility to the developer can be increased between the exposed part and the non-exposed part. The lower limit of the temperature of PEB is preferably 50°C, more preferably 80°C, and still more preferably 100°C. The upper limit of the temperature is preferably 180°C, more preferably 130°C. The lower limit of the PEB time is preferably 5 seconds, more preferably 10 seconds, and still more preferably 30 seconds. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds, and still more preferably 100 seconds.

[Development step] In this step, the exposed resist film is developed. Thereby, a predetermined resist pattern can be formed. Generally speaking, rinse with water or alcohol and other rinsing liquid after development and then dry. The development method in the development step may be alkaline development or organic solvent development.

In the case of alkali development, as the developer used for development, for example, dissolved sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, Diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (hereinafter, also referred to as "TMAH (tetramethyl ammonium hydroxide)”), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, 1,5-diazabicyclo-[4.3.0]-5 -An alkaline aqueous solution containing at least one of basic compounds such as nonene. Among these, a TMAH aqueous solution is preferred, and a 2.38% by mass TMAH aqueous solution is more preferred.

In the case of organic solvent development, examples of the developer include organic solvents such as hydrocarbon-based solvents, ether-based solvents, ester-based solvents, ketone-based solvents, and alcohol-based solvents, and solutions containing the organic solvents. Examples of the organic solvent include one or two or more of the solvents exemplified as [D] the organic solvent of the radiation-sensitive resin composition. Among these, an ester-based solvent or a ketone-based solvent is preferred. As the ester-based solvent, an acetate-based solvent is preferred, and n-butyl acetate is more preferred. As the ketone solvent, a chain ketone is preferred, and 2-heptanone is more preferred. The lower limit of the content of the organic solvent in the developer is preferably 80% by mass, more preferably 90% by mass, still more preferably 95% by mass, and particularly preferably 99% by mass. Examples of components other than the organic solvent in the developer include water and silicone oil.

Examples of the development method include: a method of immersing the substrate in a tank filled with a developer solution for a fixed period of time (dipping method); and a method of performing development by depositing the developer solution on the surface of the substrate using surface tension for a fixed period of time (coating method). Puddle method); method of spraying developer on the surface of the substrate (spray method); method of continuously spraying developer on the substrate rotating at a fixed speed while scanning the developer ejection nozzle at a fixed speed (dynamic distribution method) Wait.

As a pattern formed by this resist pattern forming method, a line and space pattern, a hole pattern, etc. are mentioned, for example.

＜Radiation-sensitive acid generator＞ The radiation-sensitive acid generator contains a compound having a sulfonate anion and a radiation-sensitive onium cation, and the sulfonate anion has a (sulfur) acetal structure, a carbonyloxy group, and the action of an acid Dissociate and provide acid-dissociable groups of alkali-soluble groups. By using the radiation-sensitive acid generator as a component of the radiation-sensitive resin composition, it is possible to form a resist pattern with good sensitivity to exposure light and excellent LWR performance and resolution. This radiation-sensitive acid generator will be described as the [B] acid generator. [Example]

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The measurement methods of various physical property values are shown below.

[Weight average molecular weight (Mw), number average molecular weight (Mn) and degree of dispersion (Mw/Mn)] The weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer are measured under the conditions described in the section of the above-mentioned <[A] polymer>. In addition, the degree of dispersion (Mw/Mn) is calculated from the measurement results of Mw and Mn.

[The content ratio of each structural unit of the polymer] The content ratio of each structural unit of the polymer is determined by ¹³ C-nuclear magnetic resonance (nuclear magnetic resonance) using a nuclear magnetic resonance device ("JNM-Delta400" of JEOL Ltd.) , NMR) analysis and determination.

＜[A] Synthesis of polymer＞ The monomers used in the synthesis of each polymer in each example and comparative example are shown below. In addition, in the following synthesis examples, unless otherwise specified, parts by mass means the value when the total mass of the monomers used is 100 parts by mass, and the mole% means the unit used The total number of moles of the body is the value when 100 mole%.

[化15]

[Synthesis Example 1] Synthesis of polymer (A-1) The monomer (M-1) and the monomer (M-3) are dissolved in propylene glycol-1-monomethyl ether (200 parts by mass) so that the molar ratio becomes 40/60. Add 6 mol% of azobisisobutyronitrile (AIBN) as a starter to prepare a monobody solution. On the other hand, propylene glycol-1-monomethyl ether (100 parts by mass) was added to an empty reaction vessel, and heated to 85°C while stirring. The monomer solution was added dropwise over 3 hours, and then further heated at 85°C for 3 hours to perform a polymerization reaction for a total of 6 hours. After the completion of the polymerization reaction, the polymerization solution was cooled to room temperature.

The cooled polymerization solution was poured into hexane (500 parts by mass with respect to the polymerization solution), and the precipitated white powder was separated by filtration. After washing the white powder separated by filtration twice with 100 parts by mass of hexane with respect to the polymerization solution, it was separated by filtration and dissolved in propylene glycol-1-monomethyl ether (300 parts by mass). Methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and the hydrolysis reaction was carried out at 70° C. for 6 hours while stirring. After the hydrolysis reaction is completed, the residual solvent is distilled off, and the obtained solid is dissolved in acetone (100 parts by mass). The resin was added dropwise to 500 parts by mass of water to solidify the resin, and the obtained solid was separated by filtration. It was dried at 50°C for 12 hours to obtain a white powdery polymer (A-1).

The Mw of the polymer (A-1) was 5,700, and the Mw/Mn was 1.61. In addition, as ^{a result of 13} C-NMR analysis, the content of each structural unit derived from the monomer (M-1) and the monomer (M-3) in the polymer (A-1) was 41.2 moles. Ear% and 58.8 mol%.

[Synthesis Example 2-Synthesis Example 9] Synthesis of Polymer (A-2)-Polymer (A-9) The polymer (A-2) to the polymer (A-9) were synthesized in the same manner as in Synthesis Example 1, except that the monomers of the type and the blending ratio shown in Table 1 below were used.

[Table 1] [A] Polymer Provide a single body of structural unit (I) Provide a single body of structural unit (II) Provide a single body of other structural units Mw Mw/Mn species Use ratio (mol%) Containing ratio of structural unit (mol%) species Use ratio (mol%) Containing ratio of structural unit (mol%) species Use ratio (mol%) Containing ratio of structural unit (mol%) Synthesis example 1 A-1 M-1 ^a 40 41.2 M-3 60 58.8 - - - 5700 1.61 Synthesis Example 2 A-2 M-1 ^a 40 42.3 M-4 60 57.7 - - - 5800 1.64 Synthesis Example 3 A-3 M-1 ^a 30 33.1 M-5 60 56.8 - - - 6100 1.65 M-2 ^a 10 10.1 Synthesis Example 4 A-4 M-1 ^a 40 41.9 M-6 60 58.1 - - - 6200 1.50 Synthesis Example 5 A-5 M-1 ^a 40 39.9 M-7 60 60.1 - - - 5500 1.54 Synthesis Example 6 A-6 M-1 ^a 40 40.1 M-8 60 59.9 - - - 5400 1.53 Synthesis Example 7 A-7 M-1 ^a 40 43.2 M-9 60 56.8 - - - 6000 1.67 Synthesis Example 8 A-8 M-1 ^a 30 30.4 M-3 60 58.2 M-10 10 11.4 6900 1.70 Synthesis Example 9 A-9 M-1 ^a 30 30.2 M-3 60 59.1 M-11 10 10.7 6800 1.65 a: Exist in the form of hydroxystyrene unit

＜[B] Synthesis of acid generator＞ [Synthesis Example 10] Synthesis of acid generator (B-1) In a reaction container, 10 mmol of the compound represented by the following formula (S-1), 10 mmol of 4-hydroxybenzaldehyde, and 1 mmol of p-toluenesulfonic acid were dissolved in toluene to make 1M. A Dean-Stark tube was set in the reaction vessel, and the solution was stirred for 5 hours under reflux conditions. After the reaction was completed, saturated aqueous sodium bicarbonate solution was added, dichloromethane was added for extraction, and the organic layer was separated. After the organic layer was dried with sodium sulfate, the solvent was removed and column purification was performed to obtain a compound represented by the following formula (Z-1) (hereinafter, also referred to as "compound (Z- 1)").

To the reaction vessel were added 10 mmol of compound (Z-1), 15 mmol of compound represented by the following formula (P-1), 15 mmol of potassium carbonate, and 100 g of acetone. After stirring the solution for 5 hours under reflux conditions, the acetone was distilled off. After adding dichloromethane, it was washed three times with ultrapure water. After drying with sodium sulfate, the solvent is distilled off and purified by column chromatography to obtain a compound represented by the following formula (B-1) (hereinafter, also referred to as "acid generator (B-1) )”).

The synthesis flow of the acid generator (B-1) is shown below.

[化16]

In the synthetic process, pTsOH is p-toluenesulfonic acid. TPS ⁺ is a triphenyl alumium cation.

[Synthesis Example 11-Synthesis Example 22] Synthesis of acid generator (B-2)-acid generator (B-13) Except for appropriately selecting the precursor, the compound represented by the following formula (B-2) to formula (B-13) (hereinafter, also referred to as "acid generator (B-2)-acid") was synthesized in the same manner as in Synthesis Example 10. Generating agent (B-13)”).

[化17]

<Preparation of Radiation Sensitive Resin Composition> [B] Acid generators other than acid generators used in the preparation of the radiation-sensitive resin composition of the comparative example, and [C] used in the preparation of the radiation-sensitive resin composition of the examples and comparative examples are shown below Acid diffusion control agent and [D] organic solvent. In addition, in the following examples and comparative examples, unless otherwise specified, parts by mass refers to the value when the mass of the polymer used is 100 parts by mass, and mole% refers to the acid used The number of moles of the generator is set to a value at 100 mole%.

[[B] Acid generators other than acid generators] b-1 to b-3: Compounds represented by the following formulas (b-1) to (b-3)

[化18]

[[C] Acid diffusion control agent] C-1 to C-4: Compounds represented by the following formulas (C-1) to (C-4)

[化19]

[[D]Organic solvent] D-1: Propylene glycol monomethyl ether acetate D-2: Propylene glycol-1-monomethyl ether

[Example 1] 100 parts by mass of (A-1) as [A] polymer, 20 parts by mass of (B-1) as [B] acid generator, and 20 parts by mass relative to 100 mol% of (B-1) Ear% (C-1) as [C] acid diffusion control agent, and (D-1) 4,800 parts by mass and (D-2) 2,000 parts by mass as [D] solvent are mixed to prepare radiation-sensitive resin composition物(R-1).

[Example 2 to Example 27 and Comparative Example 1 to Comparative Example 3] Except for using the types and contents of the components shown in Table 2 below, the radiation-sensitive resin composition (R-2) to the radiation-sensitive resin composition (R-27) and the radiation-sensitive resin composition (R-27) were prepared in the same manner as in Example 1 Resin composition (CR-1) ~ Radiation-sensitive resin composition (CR-3).

[Table 2] Radiation-sensitive resin composition [A] Polymer [B] Acid generators or [B] Acid generators other than acid generators [C] Acid diffusion control agent [D] Organic solvent species Content (parts by mass) species Content (parts by mass) species Containing ratio (mol%) Solvent Mass parts Example 1 R-1 A-1 100 B-1 20 C-1 20 D-1/D-2 4800/2000 Example 2 R-2 A-1 100 B-2 20 C-1 20 D-1/D-2 4800/2000 Example 3 R-3 A-1 100 B-3 20 C-1 20 D-1/D-2 4800/2000 Example 4 R-4 A-1 100 B-4 20 C-1 20 D-1/D-2 4800/2000 Example 5 R-5 A-1 100 B-5 20 C-1 20 D-1/D-2 4800/2000 Example 6 R-6 A-1 100 B-6 20 C-1 20 D-1/D-2 4800/2000 Example 7 R-7 A-1 100 B-7 20 C-1 20 D-1/D-2 4800/2000 Example 8 R-8 A-1 100 B-8 20 C-1 20 D-1/D-2 4800/2000 Example 9 R-9 A-1 100 B-9 20 C-1 20 D-1/D-2 4800/2000 Example 10 R-10 A-1 100 B-10 20 C-1 20 D-1/D-2 4800/2000 Example 11 R-11 A-1 100 B-11 20 C-1 20 D-1/D-2 4800/2000 Example 12 R-12 A-1 100 B-12 20 C-1 20 D-1/D-2 4800/2000 Example 13 R-13 A-1 100 B-13 20 C-1 20 D-1/D-2 4800/2000 Example 14 R-14 A-1 100 B-1 40 C-1 20 D-1/D-2 4800/2000 Example 15 R-15 A-1 100 B-1 30 C-1 20 D-1/D-2 4800/2000 Example 16 R-16 A-1 100 B-1 10 C-1 20 D-1/D-2 4800/2000 Example 17 R-17 A-1 100 B-1 20 C-2 20 D-1/D-2 4800/2000 Example 18 R-18 A-1 100 B-1 20 C-3 20 D-1/D-2 4800/2000 Example 19 R-19 A-1 100 B-1 20 C-4 20 D-1/D-2 4800/2000 Example 20 R-20 A-2 100 B-1 20 C-1 20 D-1/D-2 4800/2000 Example 21 R-21 A-3 100 B-1 20 C-1 20 D-1/D-2 4800/2000 Example 22 R-22 A-4 100 B-1 20 C-1 20 D-1/D-2 4800/2000 Example 23 R-23 A-5 100 B-1 20 C-1 20 D-1/D-2 4800/2000 Example 24 R-24 A-6 100 B-1 20 C-1 20 D-1/D-2 4800/2000 Example 25 R-25 A-7 100 B-1 20 C-1 20 D-1/D-2 4800/2000 Example 26 R-26 A-8 100 B-1 20 C-1 20 D-1/D-2 4800/2000 Example 27 R-27 A-9 100 B-1 20 C-1 20 D-1/D-2 4800/2000 Comparative example 1 CR-1 A-1 100 b-1 20 C-1 20 D-1/D-2 4800/2000 Comparative example 2 CR-2 A-1 100 b-2 20 C-1 20 D-1/D-2 4800/2000 Comparative example 3 CR-3 A-1 100 b-3 20 C-1 20 D-1/D-2 4800/2000

＜Formation of resist pattern＞ A spin coater ("CLEAN TRACK ACT12" of Tokyo Electronics Co., Ltd.) was used on the surface of a 12-inch silicon wafer with an average thickness of 20 nm underlayer film ("AL412" of Brewer Science) ) To apply the prepared radiation-sensitive resin composition, and perform soft bake (SB) at 130°C for 60 seconds, and cool at 23°C for 30 seconds to form an average thickness of 50 nm resist film. Next, the resist film was irradiated with EUV light using an EUV exposure machine ("NXE3300" from ASML, NA=0.33, lighting conditions: conventional (Conventional) s=0.89, mask imecDEFECT32FFR02). After the irradiation, PEB was performed on the resist film at 130°C for 60 seconds. Then, a 2.38% by mass TMAH aqueous solution was used to develop at 23° C. for 30 seconds to form a positive resist pattern (32 nm line and space pattern).

＜Evaluation＞ For each resist pattern formed as described above, the sensitivity, LWR performance, and resolution of each radiation-sensitive resin composition were evaluated in accordance with the following methods. Furthermore, for the length measurement of the resist pattern, a scanning electron microscope (“CG-4100” of Hitachi High-Technologies (stock)) is used. The evaluation results are shown in Table 3 below.

[Sensitivity] In the formation of the resist pattern, the exposure amount for forming the 32 nm line and space pattern was set as the optimal exposure amount, and the optimal exposure amount was set as Eop (unit: mJ/cm ² ). Regarding the sensitivity, when Eop is 30 mJ/cm ² or less, it can be evaluated as "good", and when it exceeds 30 mJ/cm ² it can be evaluated as "bad".

[LWR performance] Using the scanning electron microscope, the resist pattern formed during the formation of the resist pattern was observed from above. A total of 50 line widths are measured at an arbitrary location, and a 3 sigma value is obtained from the distribution of the measured values, and this is set as LWR (unit: nm). The smaller the value of LWR, the smaller and better the line wobble. Regarding the LWR performance, when the LWR is 4.0 nm or less, it can be evaluated as "good", and when it exceeds 4.0 nm, it can be evaluated as "bad".

[Analysis] In the optimal exposure level, the size of the smallest resist pattern analyzed is measured while changing the size of the mask pattern forming the line and space (1L/1S), and the measured value is set as the resolution (Unit: nm). The smaller the value of the resolution, the finer patterns can be formed and it is good. Regarding the resolution, when the resolution is 25 nm or less, it can be evaluated as "good", and when it exceeds 25 nm, it can be evaluated as "bad".

[table 3] Radiation-sensitive resin composition Eop (mJ/cm ² ) LWR (nm) Resolution (nm) Example 1 R-1 26 3.6 twenty three Example 2 R-2 27 3.5 twenty two Example 3 R-3 27 3.7 twenty two Example 4 R-4 27 3.7 twenty three Example 5 R-5 27 3.5 twenty two Example 6 R-6 26 3.5 twenty three Example 7 R-7 28 3.8 twenty four Example 8 R-8 27 3.9 twenty four Example 9 R-9 26 3.7 twenty three Example 10 R-10 27 3.6 twenty two Example 11 R-11 28 3.7 twenty three Example 12 R-12 29 3.8 twenty four Example 13 R-13 27 3.8 twenty three Example 14 R-14 25 3.6 twenty two Example 15 R-15 26 3.5 twenty two Example 16 R-16 29 3.8 twenty four Example 17 R-17 25 3.6 twenty three Example 18 R-18 twenty four 3.7 twenty three Example 19 R-19 twenty four 3.5 twenty three Example 20 R-20 27 3.4 twenty two Example 21 R-21 27 3.5 twenty one Example 22 R-22 28 3.7 twenty one Example 23 R-23 27 3.6 twenty two Example 24 R-24 26 3.7 twenty three Example 25 R-25 28 3.8 twenty four Example 26 R-26 27 3.4 twenty one Example 27 R-27 27 3.5 twenty one Comparative example 1 CR-1 28 4.3 26 Comparative example 2 CR-2 32 4.2 28 Comparative example 3 CR-3 34 3.9 25

As is clear from the results of Table 3, the radiation-sensitive resin composition of the examples is better in sensitivity, LWR performance, and resolution than the radiation-sensitive resin composition of the comparative example. [Industrial availability]

According to the radiation-sensitive resin composition and the resist pattern forming method of the present invention, it is possible to form a resist pattern with good sensitivity to exposure light and excellent LWR performance and resolution. The radiation-sensitive acid generator of the present invention can be preferably used as a component of the radiation-sensitive resin composition. Therefore, these can be preferably used in the processing process of semiconductor devices that are expected to be further miniaturized in the future.

no

Claims (12)

A radiation-sensitive resin composition containing: A polymer having a first structural unit, the first structural unit including a first acid dissociable group that is dissociated by the action of an acid and provides an alkali-soluble group; and Radiation-sensitive acid generator, The radiation-sensitive acid generator includes a compound having a sulfonate anion and a radiation-sensitive onium cation, The sulfonate anion has a (sulfur) acetal structure, a carbonyloxy group, and a second acid dissociable group that is dissociated by the action of an acid and provides a carboxyl group. The radiation-sensitive resin composition according to claim 1, wherein the (sulfur) acetal structure is a cyclic (sulfur) acetal structure. The radiation-sensitive resin composition according to claim 2, wherein the cyclic (sulfur) acetal structure is represented by the following formula (1),

(In formula (1), X ¹ and X ² are each independently -O- or -S-; R ¹ is a (n+2)-valent hydrocarbon group with 1 to 10 carbons; n is an integer of 0 to 2; * Represents the bonding site with the part other than the structure represented by formula (1) in the sulfonate anion). The radiation-sensitive resin composition according to claim 2 or claim 3, wherein the second acid dissociable group is represented by the following formula (2-1) or (2-2),

(In formula (2-1) and formula (2-2), ** represents the bonding site with the etheric oxygen atom of the carbonyloxy group in the sulfonate anion; in formula (2-1), R ² is a monovalent hydrocarbon group with 1 to 20 carbons or a group containing the (sulfur) acetal structure; R ³ and R ⁴ are each independently a monovalent hydrocarbon group with 1 to 20 carbons, or these groups are bonded to each other And form part of an alicyclic structure with 3 to 20 ring members together with the carbon atoms to which they are bonded; in formula (2-2), R ⁶ , R ⁷ and R ⁹ are each independently a hydrogen atom or carbon A hydrocarbon group of 1 to 20; R ⁵ and R ⁸ are each independently a monovalent hydrocarbon group of 1 to 20 carbons, or a ring member formed by combining these groups with the unsaturated carbon chains to which they are bonded Part of the unsaturated alicyclic structure of 4-20). The radiation-sensitive resin composition according to any one of claims 1 to 4, wherein the sulfonate anion further has an alicyclic structure. The radiation-sensitive resin composition according to any one of claims 1 to 5, wherein the sulfonate anion further has a partial structure represented by the following formula (3),

(In formula (3), R ¹⁰ and R ¹¹ are each independently a hydrogen atom, a fluorine atom, a C 1-20 monovalent hydrocarbon group or a C 1-20 monovalent fluorinated hydrocarbon group; wherein, R ¹⁰ and R ^At least one of 11 is a fluorine atom or a monovalent fluorinated hydrocarbon group with 1 to 20 carbon atoms; m is an integer of 1 to 10; when m is 2 or more, multiple R ¹⁰ are the same or different from each other, and multiple R ¹¹ are the same or different from each other; *** represents a bonding site with a part other than the structure represented by formula (3) in the sulfonate anion). The radiation-sensitive resin composition according to any one of claims 1 to 6, wherein the polymer further has a second structural unit containing a phenolic hydroxyl group. A method for forming a resist pattern includes: The step of directly or indirectly coating the radiation-sensitive resin composition on the substrate; A step of exposing the resist film formed by the coating step; and The step of developing the exposed resist film, The radiation-sensitive resin composition contains: A polymer having a first structural unit, the first structural unit including a first acid dissociable group that is dissociated by the action of an acid and provides an alkali-soluble group; and Radiation-sensitive acid generator, The radiation-sensitive acid generator includes a compound having a sulfonate anion and a radiation-sensitive onium cation, The sulfonate anion has a (sulfur) acetal structure, a carbonyloxy group, and a second acid dissociable group that is dissociated by the action of an acid and provides a carboxyl group. A radiation-sensitive acid generator, which contains a compound having a sulfonate anion and a radiation-sensitive onium cation. In the radiation-sensitive acid generator, The sulfonate anion has a (sulfur) acetal structure, a carbonyloxy group, and an acid dissociable group that is dissociated by the action of an acid and provides a carboxyl group. The radiation-sensitive acid generator according to claim 9, wherein the sulfonate anion has a cyclic (sulfur) acetal structure represented by the following formula (1) and the following formula (2-1) or (2-2) The acid dissociable group represented by,

(In formula (1), X ¹ and X ² are each independently -O- or -S-; R ¹ is a (n+2)-valent hydrocarbon group with 1 to 10 carbons; n is an integer of 0 to 2; * Indicates the bonding site with the part other than the structure represented by formula (1) in the sulfonate anion)

(In formula (2-1) and formula (2-2), ** represents the bonding site with the etheric oxygen atom of the carbonyloxy group in the sulfonate anion; in formula (2-1), R ² is a monovalent hydrocarbon group with 1 to 20 carbons or a group containing the (sulfur) acetal structure; R ³ and R ⁴ are each independently a monovalent hydrocarbon group with 1 to 20 carbons, or these groups are bonded to each other And form part of an alicyclic structure with 3 to 20 ring members together with the carbon atoms to which they are bonded; in formula (2-2), R ⁶ , R ⁷ and R ⁹ are each independently a hydrogen atom or carbon A hydrocarbon group of 1 to 20; R ⁵ and R ⁸ are each independently a monovalent hydrocarbon group of 1 to 20 carbons, or the number of ring members formed by combining these groups with the carbon atoms to which they are bonded is 4 ～20 part of the unsaturated alicyclic structure). The radiation-sensitive acid generator according to claim 9 or claim 10, wherein the sulfonate anion further has an alicyclic structure. The radiation-sensitive acid generator according to claim 10 or claim 11, wherein the sulfonate anion further has a partial structure represented by the following formula (3),

(In formula (3), R ¹⁰ and R ¹¹ are each independently a hydrogen atom, a fluorine atom, a C 1-20 monovalent hydrocarbon group or a C 1-20 monovalent fluorinated hydrocarbon group; wherein, R ¹⁰ and R ^At least one of 11 is a fluorine atom or a monovalent fluorinated hydrocarbon group with 1 to 20 carbon atoms; m is an integer of 1 to 10; when m is 2 or more, multiple R ¹⁰ are the same or different from each other, and multiple R ¹¹ are the same or different from each other; *** represents a bonding site with a part other than the structure represented by formula (3) in the sulfonate anion).