JP7447725B2 - Radiation sensitive resin composition and resist pattern forming method - Google Patents

Description

The present invention relates to a radiation-sensitive resin composition, a resist pattern forming method, and a compound.

The radiation-sensitive resin composition used for microfabrication by lithography is capable of radiating far ultraviolet rays such as ArF excimer laser light (wavelength 193 nm) and KrF excimer laser light (wavelength 248 nm), extreme ultraviolet rays (EUV) (wavelength 13.5 nm), etc. Acid is generated in the exposed area by irradiation with radiation such as electromagnetic waves or charged particle beams such as electron beams, and a chemical reaction catalyzed by this acid causes a difference in the rate of dissolution in the developer between the exposed area and the non-exposed area. This forms a resist pattern on the substrate.

In addition to having good sensitivity to exposure light such as extreme ultraviolet rays and electron beams, radiation-sensitive resin compositions are required to have excellent LWR (Line Width Roughness) performance and resolution.

In order to meet these demands, the types and molecular structures of polymers, acid generators, and other components used in radiation-sensitive resin compositions have been studied, and their combinations have also been studied in detail (particularly (See JP-A No. 2010-134279, JP-A No. 2014-224984, and JP-A No. 2016-047815).

Japanese Patent Application Publication No. 2010-134279 JP2014-224984A Japanese Patent Application Publication No. 2016-047815

Nowadays, the miniaturization of resist patterns has progressed to the level of line widths of 40 nm or less, and the above-mentioned performance requirements have further increased, and the above-mentioned conventional radiation-sensitive resin compositions cannot satisfy the above-mentioned demands. has not been completed.

The present invention has been made based on the above-mentioned circumstances, and its purpose is to provide a radiation-sensitive resist pattern that has good sensitivity to exposure light and can form a resist pattern with excellent LWR performance and resolution. An object of the present invention is to provide a resin composition, a resist pattern forming method, and a compound.

（式（１）中、Ａｒ^１は、環員数６～２０のアレーンから（ｓ＋１）個の芳香環上の水素原子を除いた基である。ｓは、０～１１の整数である。ｓが１の場合、Ｒ^１は、炭素数１～２０の有機基、ヒドロキシ基、ニトロ基又はハロゲン原子である。ｓが２以上の場合、複数のＲ^１は、互いに同一又は異なり、炭素数１～２０の有機基、ヒドロキシ基、ニトロ基若しくはハロゲン原子であるか、又はこれらが互いに合わせられこれらが結合する炭素原子と共に構成される環員数４～２０の脂環構造若しくは環員数４～２０の脂肪族複素環構造の一部である。Ａｒ^２は、環員数６～２０のアレーンからｔ個の芳香環上の水素原子を除いた基である。ｔは、０～１０の整数である。ｔが１の場合、Ｒ^２は、炭素数１～２０の１価の有機基、ヒドロキシ基、ニトロ基又はハロゲン原子である。ｔが２以上の場合、複数のＲ^２は、互いに同一又は異なり、炭素数１～２０の１価の有機基、ヒドロキシ基、ニトロ基又はハロゲン原子であるか、又はこれらが互いに合わせられこれらが結合する炭素原子と共に構成される環員数４～２０の脂環構造若しくは環員数４～２０の脂肪族複素環構造の一部である。Ａｒ^３は、環員数６～２０のアレーンからｕ個の芳香環上の水素原子を除いた基である。ｕは、０～１０の整数である。ｕが１の場合、Ｒ^３は、炭素数１～２０の１価の有機基、ヒドロキシ基、ニトロ基又はハロゲン原子である。ｕが２以上の場合、複数のＲ^３は、互いに同一又は異なり、炭素数１～２０の１価の有機基、ヒドロキシ基、ニトロ基又はハロゲン原子であるか、又はこれらが互いに合わせられこれらが結合する炭素原子と共に構成される環員数４～２０の脂環構造若しくは環員数４～２０の脂肪族複素環構造の一部である。但し、Ａｒ^２及びＡｒ^３を与えるアレーンのうち少なくとも一方が多環のアレーンである。Ｘ^－は、下記式（２－１）で表されるスルホン酸アニオン又はカルボン酸アニオンである。）

（式（２－１）中、Ｒ^ｐ１は、環員数５以上の環構造を含む１価の基である。Ｒ^ｐ２は、２価の連結基である。Ｒ^ｐ３及びＲ^ｐ４は、それぞれ独立して、水素原子、フッ素原子、炭素数１～２０の１価の炭化水素基又は炭素数１～２０の１価のフッ素化炭化水素基である。Ｒ^ｐ５及びＲ^ｐ６は、それぞれ独立して、フッ素原子又は炭素数１～２０の１価のフッ素化炭化水素基である。ｎ^ｐ１は、０～１０の整数である。ｎ^ｐ２は、０～１０の整数である。ｎ^ｐ３は、０～１０の整数である。但し、ｎ^ｐ１＋ｎ^ｐ２＋ｎ^ｐ３は、１以上３０以下である。ｎ^ｐ１が２以上の場合、複数のＲ^ｐ２は互いに同一又は異なる。ｎ^ｐ２が２以上の場合、複数のＲ^ｐ３は互いに同一又は異なり、複数のＲ^ｐ４は互いに同一又は異なる。ｎ^ｐ３が２以上の場合、複数のＲ^ｐ５は互いに同一又は異なり、複数のＲ^ｐ６は互いに同一又は異なる。） The invention made to solve the above problems consists of a polymer having a structural unit containing an acid-dissociable group (hereinafter also referred to as "[A] polymer"), and a compound represented by the following formula (1) ( Hereinafter, it is a radiation-sensitive resin composition containing a "[Z] compound").

(In formula (1), Ar ¹ is a group obtained by removing hydrogen atoms on (s+1) aromatic rings from an arene having 6 to 20 ring members. s is an integer from 0 to 11. 1, R ¹ is an organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When s is 2 or more, multiple R ¹ 's are the same or different and have 1 to 20 carbon atoms. 20 organic groups, hydroxy groups, nitro groups, or halogen atoms, or an alicyclic structure with 4 to 20 ring members or an alicyclic structure with 4 to 20 ring members formed by combining these with the carbon atoms to which they are bonded. It is part of a group heterocyclic structure. Ar ² is a group obtained by removing hydrogen atoms on t aromatic rings from an arene having 6 to 20 ring members. t is an integer of 0 to 10. t When is 1, R ² is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When t is 2 or more, R ² are the same or different from each other, A monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or an alicyclic structure having 4 to 20 ring members formed by combining these with the carbon atoms to which they are bonded. It is part of an aliphatic heterocyclic structure having 4 to 20 ring members.Ar ³ is a group obtained by removing hydrogen atoms on u aromatic rings from an arene having 6 to 20 ring members.u is 0 to is an integer of 10. When u is 1, R ³ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When u is 2 or more, multiple R ³ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or a 4-membered ring formed by combining these together with the carbon atom to which they are bonded. It is a part of an alicyclic structure having ~20 members or an aliphatic heterocyclic structure having 4 to 20 ring members.However, at least one of the arenes providing Ar ² and Ar ³ is a polycyclic arene ^. It is a sulfonic acid anion or a carboxylic acid anion represented by the following formula (2-1).)

(In formula (2-1), R ^p1 is a monovalent group containing a ring structure with 5 or more ring members. R ^p2 is a divalent linking group. R ^p3 and R ^p4 are each independently and is a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms.R ^p5 and R ^p6 are each independently , a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. n ^p1 is an integer of 0 to 10. n ^p2 is an integer of 0 to 10. n ^p3 is 0 is an integer of ~10. However, n ^p1 + n ^p2 + n ^p3 is 1 or more and 30 or less. When n ^p1 is 2 or more, the plurality of R ^p2s are the same or different from each other. When n ^p2 is 2 or more, A plurality of R ^p3s are the same or different from each other, and a plurality of R ^p4s are the same or different from each other. When n ^p3 is 2 or more, a plurality of R ^p5s are the same or different from each other, and a plurality of R ^p6s are the same or different from each other.)

Another invention made to solve the above problems includes a step of directly or indirectly applying the above-mentioned radiation-sensitive resin composition to a substrate, and a step of exposing a resist film formed by the above-mentioned coating step. and a step of developing the exposed resist film.

Yet another invention made to solve the above problem is a compound ([Z] compound) represented by the above formula (1).

According to the radiation-sensitive resin composition and resist pattern forming method of the present invention, it is possible to form a resist pattern that has good sensitivity to exposure light and excellent LWR performance and resolution. The compound of the present invention can be suitably used as a component of the radiation-sensitive resin composition. Therefore, the radiation-sensitive resin composition, the resist pattern forming method, and the compound can be suitably used in the processing of semiconductor devices, which are expected to become increasingly finer in the future.

Hereinafter, the radiation-sensitive resin composition, resist pattern forming method, and compound of the present invention will be explained in detail.

<Radiation-sensitive resin composition>
The radiation-sensitive resin composition contains a [A] polymer and a [Z] compound. The radiation-sensitive resin composition usually contains an organic solvent (hereinafter also referred to as "[D] organic solvent"). The radiation-sensitive resin composition preferably contains a radiation-sensitive acid generator other than the [Z] compound (hereinafter referred to as "[B] acid generator") and/or an acid diffusion control agent other than the [Z] compound. (hereinafter also referred to as "[C] acid diffusion control agent"). The radiation-sensitive resin composition may contain other optional components within a range that does not impair the effects of the present invention.

By containing the [A] polymer and the [Z] compound, the radiation-sensitive resin composition has good sensitivity to exposure light and can form a resist pattern with excellent LWR performance and resolution. can. Although the reason why the radiation-sensitive resin composition achieves the above effects by having the above structure is not necessarily clear, it can be inferred as follows, for example. That is, since the [Z] compound contained in the radiation-sensitive resin composition has a cation with a specific structure, it becomes easier to absorb exposure light, improving the efficiency of acid generation by exposure, and as a result, the radiation-sensitive resin composition It is thought that the resin composition has good sensitivity to exposure light and can form a resist pattern with excellent LWR performance and resolution.

Each component contained in the radiation-sensitive resin composition will be explained below.

<[A] Polymer>
[A] The polymer has a structural unit (hereinafter also referred to as "structural unit (I)") containing an acid-dissociable group. The radiation-sensitive resin composition can contain one or more kinds of [A] polymers.

[A] It is preferable that the polymer further has a structural unit containing a phenolic hydroxyl group (hereinafter also referred to as "structural unit (II)"). [A] It is preferable that the polymer further has a structural unit (hereinafter also referred to as "structural unit (III)") containing a partial structure represented by formula (4) described below. [A] The polymer may further have structural units other than structural units (I) to (III) (hereinafter also simply referred to as "other structural units").

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

[Structural unit (I)]
Structural unit (I) is a structural unit containing an acid dissociable group. As used herein, the term "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group, hydroxy group, etc., and is dissociated by the action of an acid to give a carboxy group, hydroxy group, etc. Upon exposure to light, the acid dissociable group is dissociated by the action of the acid generated from the [Z] compound, [B] acid generator, etc., and the [A] polymer is dissolved in the developer between the exposed area and the non-exposed area. Due to the difference in properties, a resist pattern can be formed. [A] The polymer can contain one or more types of structural units (I).

Examples of the structural unit (I) include structural units represented by the following formulas (3-1A) to (3-2B) (hereinafter also referred to as "structural units (I-1A) to (I-2B)"), etc. can be mentioned. Note that, for example, in the following formula (3-1A ⁾ , -C ^{( R}

In the above formulas (3-1A), (3-1B), (3-1C), (3-2A) and (3-2B), R ^T is each independently a hydrogen atom, a fluorine atom, a methyl group Or a trifluoromethyl group.

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

In the above formula (3-1C), R ^A is a hydrogen atom. R ^B and R ^C each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^D is a divalent hydrocarbon group having 1 to 20 carbon atoms that constitutes an unsaturated alicyclic structure having 4 to 20 ring members together with the carbon atoms to which R ^A , R ^B and R ^C are bonded.

In the above formulas (3-2A) and (3-2B), R ^U and R ^V are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^W is each Independently, it is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or an alicyclic structure having 3 to 20 ring members formed by combining R ^U and R ^V together with the carbon atoms to which they are bonded. or is part of an aliphatic heterocyclic structure having 5 to 20 ring members, in which R ^U and R ^W are combined together with the carbon atom to which R ^U is bonded and the oxygen atom to which R ^W is bonded. .

As used herein, "carbon number" refers to the number of carbon atoms constituting a group. In addition, in this specification, "number of ring members" refers to the number of atoms constituting the rings of alicyclic structures, aromatic carbocyclic structures, aliphatic heterocyclic structures, and aromatic heterocyclic structures, and in the case of polycyclic structures, This refers to the number of atoms that make up this polycyclic ring.

In this specification, the "hydrocarbon group" includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. This "hydrocarbon group" may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The term "chain hydrocarbon group" refers to a hydrocarbon group that does not contain a cyclic structure and is composed only of a chain structure, and includes both linear hydrocarbon groups and branched hydrocarbon groups. "Alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure as a ring structure and does not contain an aromatic ring structure, and includes a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic hydrocarbon group. Contains both hydrocarbon groups. However, it is not necessary to be composed only of an alicyclic structure, and a part thereof may include a chain structure. "Aromatic hydrocarbon group" refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to consist only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure.

The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^X , R ^Y , R ^Z , R ^B , R ^C , R ^U , R ^V or R ^W is, for example, Examples include a valent chain hydrocarbon group, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

Examples of monovalent chain hydrocarbon groups having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, iso-butyl group, tert Examples include alkyl groups such as -butyl, alkenyl groups such as ethenyl, propenyl and butenyl, and alkynyl groups such as ethynyl, propynyl and butynyl.

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

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, benzyl group, phenethyl group, naphthylmethyl group, and anthrylmethyl group. Examples include aralkyl groups such as groups.

Examples of alicyclic structures having 3 to 20 ring members formed by combining R ^Y and R ^Z together with the carbon atoms to which they are bonded include monocyclic structures such as cyclopropane structure, cyclobutane structure, cyclopentane structure, and cyclohexane structure. Polycyclic saturated alicyclic structures such as saturated alicyclic structures, norbornane structures, and adamantane structures, monocyclic unsaturated alicyclic structures such as cyclopropene structures, cyclobutene structures, cyclopentene structures, and cyclohexene structures, and polycyclic structures such as norbornene structures. Examples include unsaturated alicyclic structures.

The divalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^D is, for example, a carbon group represented by R ^X , R ^Y , R ^Z , R ^B , R ^C , R ^U , R ^V or R ^W Examples of the monovalent hydrocarbon group having numbers 1 to 20 include groups obtained by removing one hydrogen atom from the groups listed above.

Examples of the unsaturated alicyclic structure having 4 to 20 ring members that R ^D constitutes with the carbon atoms to which R ^A , R ^B and R ^C are bonded include monocyclic unsaturated structures such as a cyclobutene structure, a cyclopentene structure, and a cyclohexene structure. Examples include polycyclic unsaturated alicyclic structures such as alicyclic structures and norbornene structures.

For example, an alicyclic structure having 3 to 20 ring members formed by combining R ^U and R ^V with each other and the carbon atoms to which they are bonded is, for example, an alicyclic structure in which R ^Y and R ^Z are combined with each other and formed with the carbon atoms to which they are bonded. Examples of the alicyclic structure having 3 to 20 ring members include structures similar to those exemplified.

Examples of aliphatic heterocyclic structures having 4 to 20 ring members formed by combining R ^U and R ^W together with the carbon atom to which R ^U is bonded and the oxygen atom to which R ^W are bonded include oxacyclobutane structures and oxacyclopentane structures. structure, a saturated oxygen-containing heterocyclic structure such as an oxacyclohexane structure, an unsaturated oxygen-containing heterocyclic structure such as an oxacyclobutene structure, an oxacyclopentene structure, an oxacyclohexene structure, and the like.

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

R ^X is preferably a chain hydrocarbon group or an aromatic hydrocarbon group, more preferably an alkyl group or an aryl group, and even more preferably a methyl group, ethyl group, i-propyl group, tert-butyl group, or phenyl group.

R ^Y and R ^Z are preferably part of an alicyclic structure having 3 to 20 ring members formed by combining them together with the carbon atoms to which they are bonded. The alicyclic structure is preferably a saturated alicyclic structure, more preferably a monocyclic saturated alicyclic structure, and even more preferably a cyclopentane structure or a cyclohexane structure.

As R ^B , a hydrogen atom is preferable.

R ^C is preferably a hydrogen atom or a chain hydrocarbon group, more preferably a hydrogen atom or an alkyl group, and even more preferably a hydrogen atom or a methyl group.

The unsaturated alicyclic structure having 4 to 20 ring members that R ^D constitutes with the carbon atoms to which R ^A , R ^B and R ^C are bonded is preferably a monocyclic unsaturated alicyclic structure, such as a cycloheptane structure or a cyclohexene structure. structure is more preferred.

The structural unit (I) is preferably a structural unit (I-1A), a structural unit (I-1B) or a structural unit (I-1C), and the structural unit (I-1A) or the structural unit (I-1C) is More preferred.

Structural units (I-1A) include structural units represented by the following formulas (3-1A-1) to (3-1A-5) (hereinafter referred to as "structural units (I-1A-1) to (I-1A-1)"). 1A-5)” is preferred.

In the above formulas (3-1A-1) to (3-1A-5), R ^T has the same meaning as in the above formula (3-1A).

The structural unit (I-1C) is a structural unit represented by the following formula (3-1C-1) to (3-1C-2) (hereinafter referred to as "structural unit (I-1C-1) to (I-1C-1)"). 1C-2)” is preferred.

In the above formulas (3-1C-1) to (3-1C-2), R ^T has the same meaning as in the above formula (3-1C).

[A] The lower limit of the content of the structural unit (I) in the polymer is preferably 30 mol%, more preferably 40 mol%, and 50 mol% based on the total structural units constituting the polymer [A]. is even more preferable. The upper limit of the content ratio is preferably 90 mol%, more preferably 80 mol%, and even more preferably 70 mol%. By setting the content of the structural unit (I) within the above range, the sensitivity to exposure light, LWR performance, and resolution of the radiation-sensitive resin composition can be further improved.

[Structural unit (II)]
Structural unit (II) is a structural unit containing a phenolic hydroxyl group. The term "phenolic hydroxyl group" refers not only to hydroxy groups directly connected to benzene rings, but also to all hydroxy groups directly connected to aromatic rings.

In the case of KrF exposure, EUV exposure or electron beam exposure, the [A] polymer having the structural unit (II) can further increase the sensitivity of the radiation-sensitive resin composition to exposure light. Therefore, when the [A] polymer has the structural unit (II), the radiation-sensitive resin composition can be suitably used as a radiation-sensitive resin composition for KrF exposure, EUV exposure, or electron beam exposure. Can be done.

Examples of the structural unit (II) include structural units represented by the following formulas (II-1) to (II-14) (hereinafter also referred to as "structural units (II-1) to (II-14)"), etc. can be mentioned.

In the above formulas (II-1) to (II-14), R ^P is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

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

The structural unit (II) is preferably a structural unit (II-1), a structural unit (II-2), or a combination thereof.

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

[Structural unit (III)]
The structural unit (III) is a structural unit containing a group represented by the following formula (4). [A] By further having the structural unit (III), the polymer can further improve the sensitivity to exposure light, LWR performance, and resolution of the radiation-sensitive resin composition.

In the above formula (4), R ¹² is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ¹³ and R ¹⁴ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. ** indicates a bonding site with a moiety other than the group represented by the above formula (4).

As used herein, "organic group" means a group containing at least one carbon atom.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹² include a monovalent hydrocarbon group having 1 to 20 carbon atoms, and a divalent hetero atom-containing between carbon atoms of the hydrocarbon group. group (hereinafter also referred to as "group (α)"), a group in which some or all of the hydrogen atoms of the above hydrocarbon group are substituted with a monovalent heteroatom-containing group (hereinafter referred to as "group (β)") ), a group in which part or all of the hydrogen atoms of the above group (α) are substituted with a monovalent heteroatom-containing group (hereinafter also referred to as “group (γ)”), and the like.

As the monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms represented by R ¹³ and R ¹⁴ , for example, at least one hydrogen atom possessed by the monovalent hydrocarbon group having 1 to 10 carbon atoms is replaced by a fluorine atom. Examples include groups substituted with . Specifically, partially fluorinated alkyl groups such as fluoromethyl group, difluoromethyl group, difluoroethyl group, trifluoroethyl group, trifluoropropyl group; trifluoromethyl group, pentafluoroethyl group, hexafluoropropyl group, etc. Examples include perfluoroalkyl groups.

As R ¹² , a hydrogen atom is preferable.

R ¹³ and R ¹⁴ are preferably a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms, more preferably a monovalent perfluoroalkyl group having 1 to 10 carbon atoms, and even more preferably a trifluoromethyl group.

As the group represented by the above formula (4), a hydroxybis(perfluoroalkyl)methyl group is preferable, and a hydroxybis(trifluoromethyl)methyl group is more preferable.

Examples of the structural unit (III) include structural units represented by the following formulas (III-1) to (III-2) (hereinafter also referred to as "structural units (III-1) to (III-2)"). Can be mentioned.

In the above formulas (III-1) and (III-2), R ^Q is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Z is a group represented by the above formula (4).

In the above formula (III-1), L ¹ is a single bond or a divalent organic group having 1 to 20 carbon atoms.

In the above formula (III-2), L ² is a single bond or a divalent organic group having 1 to 20 carbon atoms. R ¹⁵ , R ¹⁶ and R ¹⁷ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. s is an integer from 1 to 4. When s is 2 or more, multiple R ^15s are the same or different, multiple R ^16s are the same or different, and multiple R ^17s are the same or different.

Examples of the divalent organic group having 1 to 20 carbon atoms represented by L ¹ and L ² include the monovalent organic group having 1 to 20 carbon atoms represented by R ¹² in the above formula (4). Examples include a group obtained by removing one hydrogen atom from a group.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹⁵ , R ¹⁶ and R ¹⁷ include the monovalent organic group having 1 to 20 carbon atoms represented by R ¹² in the above formula (4). Examples include groups similar to those exemplified as .

R ^Q in the above formula (III-1) is preferably a hydrogen atom or a methyl group, and more preferably a methyl group.

R ^Q in the above formula (III-2) is preferably a hydrogen atom.

L ¹ is preferably a divalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

L ² is preferably a divalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a divalent chain hydrocarbon group having 1 to 20 carbon atoms.

A hydrogen atom is preferable as R ¹⁵ and R ¹⁶ .

R ¹⁷ is preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

s is preferably 1.

The structural unit (III-1) is preferably a structural unit represented by the following formula (III-1-1) (hereinafter also referred to as "structural unit (III-1-1)"); As 2), a structural unit represented by the following formula (III-2-1) (hereinafter also referred to as "structural unit (III-2-1)") is preferable.

In the above formulas (III-1-1) and (III-2-1), R ^Q and Z have the same meanings as in the above formulas (III-1) and (III-2), respectively.

[A] When the polymer has a structural unit (III), the lower limit of the content ratio of the structural unit (III) in the [A] polymer is 1 for all structural units constituting the [A] polymer. Mol% is preferred, and 5 mol% is more preferred. The upper limit of the content ratio is preferably 30 mol%, more preferably 20 mol%. By setting the content ratio of the structural unit (III) within the above range, the sensitivity to exposure light, LWR performance, and resolution of the radiation-sensitive resin composition can be further improved.

[Other structural units]
Examples of other structural units include, for example, structural units containing an alcoholic hydroxyl group other than the structural unit (III) above, structural units containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof.

[A] When the polymer has other structural units, the upper limit of the content of the other structural units is preferably 20 mol%, and 10 mol% based on the total structural units constituting the [A] polymer. is more preferable.

The lower limit of the content of the [A] polymer in the radiation-sensitive resin composition is preferably 50% by mass, and 70% by mass based on all components other than the organic solvent [D] in the radiation-sensitive resin composition. % is more preferable, and 80% by mass is even more preferable. The upper limit of the content ratio is preferably 99% by mass, more preferably 95% by mass.

[A] The lower limit of the polystyrene equivalent weight average molecular weight (Mw) of the polymer measured by gel permeation chromatography (GPC) is preferably 1,000, more preferably 3,000, even more preferably 4,000, 5, 000 is particularly preferred. The upper limit of Mw is preferably 50,000, more preferably 30,000, even more preferably 20,000, and particularly preferably 10,000. [A] By setting the Mw of the polymer within the above range, the coating properties of the radiation-sensitive resin composition can be improved, and as a result, the sensitivity to exposure light and LWR of the radiation-sensitive resin composition can be improved. Performance and resolution can be further improved.

[A] The upper limit of the ratio of Mw to polystyrene equivalent number average molecular weight (Mn) determined by GPC of the polymer (hereinafter also referred to as "dispersity" or "Mw/Mn") is preferably 5, more preferably 3, 2 is more preferred, and 1.8 is particularly preferred. The lower limit of the above ratio is usually 1.0, preferably 1.1.

The Mw and Mn of the polymer in this specification are values measured using gel permeation chromatography (GPC) under the following conditions.
GPC columns: 2 “G2000HXL”, 1 “G3000HXL” and 1 “G4000HXL” from Tosoh Co., Ltd. Column temperature: 40°C
Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL/min Sample concentration: 1.0% by mass
Sample injection volume: 100μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

<[Z] compound>
The [Z] compound is a compound represented by the following formula (1), which will be described later. The radiation-sensitive resin composition can contain one or more [Z] compounds.

The [Z] compound can be irradiated with radiation in the radiation-sensitive resin composition depending on the type of anion represented by X ⁻ in the following formula (1) (hereinafter also referred to as “anion (X)”). It has the effect of generating acid or controlling the diffusion phenomenon of acid generated from an acid generator or the like upon exposure in the resist film, and the effect of suppressing undesirable chemical reactions in non-exposed areas. In other words, the [Z] compound functions as a radiation-sensitive acid generator or an acid diffusion control agent in the radiation-sensitive resin composition, depending on the type of anion (X). Specifically, when the anion (X) is a sulfonic acid anion (hereinafter also referred to as "anion (X-1)") represented by the following formula (2-1), the [Z] compound functions as a radiation-sensitive acid generator, and when the anion (X) is a carboxylic acid anion (hereinafter also referred to as "anion (X-2)"), the [Z] compound functions as an acid diffusion control agent. do. Note that in this specification, the moiety other than the moiety represented by A ^- in the compound represented by the following formula (1) is referred to as a "cation (Y)."

When the [Z] compound functions as a radiation-sensitive acid generator, examples of the radiation include those similar to those exemplified as exposure light in the exposure step of the resist pattern forming method described below. Due to the acid generated from the [Z] compound upon irradiation with radiation, the acid-dissociable groups contained in the structural unit (I) of the [A] polymer are dissociated to form carboxyl groups, and the connection between the exposed and non-exposed areas is A resist pattern can be formed by the difference in solubility of the resist film in the developer between the two.

[Z] The lower limit of the temperature at which the acid generated from the compound dissociates the acid-dissociable group contained in the structural unit (I) of the polymer [A] is preferably 80°C, more preferably 90°C, and 100°C. is even more preferable. The upper limit of the above temperature is preferably 130°C, more preferably 120°C, and even more preferably 110°C. The lower limit of the time for the acid to dissociate the acid-dissociable group is preferably 10 seconds, more preferably 1 minute. The upper limit of the above time is preferably 10 minutes, more preferably 2 minutes.

In the above formula (1), Ar ¹ is a group obtained by removing hydrogen atoms on (s+1) aromatic rings from an arene having 6 to 20 ring members. s is an integer from 0 to 11. When s is 1, R ¹ is an organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When s is 2 or more, the plurality of R ¹ 's are the same or different and are an organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or a carbon atom to which these are combined and bonded. It is a part of an alicyclic structure having 4 to 20 ring members or an aliphatic heterocyclic structure having 4 to 20 ring members, which is formed together with atoms. Ar ² is a group obtained by removing hydrogen atoms on t aromatic rings from an arene having 6 to 20 ring members. t is an integer from 0 to 10. When t is 1, R ² is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When t is 2 or more, the plural R ² 's are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or they are combined with each other and these are It is part of an alicyclic structure having 4 to 20 ring members or an aliphatic heterocyclic structure having 4 to 20 ring members, which is formed together with the bonding carbon atoms. Ar ³ is a group obtained by removing hydrogen atoms on u aromatic rings from an arene having 6 to 20 ring members. u is an integer from 0 to 10. When u is 1, R ³ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When u is 2 or more, the plurality of R ³ 's are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or they are combined with each other and these are It is part of an alicyclic structure having 4 to 20 ring members or an aliphatic heterocyclic structure having 4 to 20 ring members, which is formed together with the bonding carbon atoms. However, at least one of the arenes providing Ar ² and Ar ³ is a polycyclic arene. X ⁻ is a sulfonic acid anion or a carboxylic acid anion represented by the following formula (2-1) described below.

Examples of arenes having 6 to 20 ring members that provide Ar ¹ include benzene, naphthalene, anthracene, phenanthrene, tetracene, and pyrene. Among these, benzene or naphthalene is preferred, and benzene is more preferred.

Examples of arenes having 6 to 20 ring members that provide Ar ² or Ar ³ include benzene, naphthalene, anthracene, phenanthrene, tetracene, and pyrene. Among these, benzene or naphthalene is preferred from the viewpoint of further improving the sensitivity to exposure light, LWR performance, and resolution of the radiation-sensitive resin composition.

At least one of the above arenes providing Ar ² and Ar ³ is a polycyclic arene. Examples of polycyclic arenes include arenes other than benzene among those exemplified as the above-mentioned arenes having 6 to 20 ring members that give Ar ² or Ar ³ . Further, it is preferable that at least one of the above arenes giving Ar ² and Ar ³ is an arene in which two or three benzene rings are condensed, and at least one of the above arenes giving Ar ² and Ar ³ is an arene with two or three benzene rings condensed. is more preferably a fused arene, and even more preferably one of the above arenes giving Ar ² and Ar ³ is an arene fused with two benzene rings. In this case, the sensitivity to exposure light, LWR performance, and resolution of the radiation-sensitive resin composition can be further improved. Examples of arenes in which two benzene rings are condensed include naphthalene, and examples of arenes in which three benzene rings are condensed include anthracene, phenanthrene, and phenalene.

Examples of the organic group having 1 to 20 carbon atoms represented by R ¹ , R ² or R ³ include the monovalent organic group having 1 to 20 carbon atoms represented by R ¹² in the above formula (4). Examples include groups similar to the above group.

Examples of alicyclic structures having 4 to 20 ring members formed by combining a plurality of R ¹ together with carbon atoms to which they are bonded include monocyclic saturated alicyclic structures such as a cyclobutane structure, a cyclopentane structure, and a cyclohexane structure; Polycyclic saturated alicyclic structures such as norbornane structure and adamantane structure, monocyclic unsaturated alicyclic structures such as cyclopropene structure, cyclobutene structure, cyclopentene structure, and cyclohexene structure, and polycyclic unsaturated alicyclic structures such as norbornene structure. Examples include.

An alicyclic structure having 4 to 20 ring members, in which a plurality of R ² are combined with each other and the carbon atoms to which they are bonded, or an alicyclic structure having 4 to 20 ring members, in which a plurality of R ³ are combined together and together with the carbon atoms to which they are bonded. Examples of the alicyclic structure of 20 include those similar to the alicyclic structure exemplified as an alicyclic structure having 4 to 20 ring members formed by combining a plurality of R ¹ together with the carbon atoms to which they are bonded. .

Examples of aliphatic heterocyclic structures having 4 to 20 ring members formed by combining a plurality of R ¹ together with the carbon atoms to which they are bonded include, for example, an azacyclopentane structure, an azacyclohexane structure, a thiacyclopentane structure, and a thiacyclohexane structure. structure, oxacyclopentane structure, oxacyclohexane structure, dioxacyclopentane structure, etc.

An aliphatic heterocyclic structure having 4 to 20 ring members in which a plurality of R ² are combined with each other and the carbon atoms to which they are bonded, or an aliphatic heterocyclic structure having a ring member number of 4 to 20 in which a plurality of R ³ is combined with each other and the carbon atoms to which they are bonded. Examples of 4-20 aliphatic heterocyclic structures include aliphatic heterocyclic structures exemplified as 4-20 ring member aliphatic heterocyclic structures in which a plurality of R ^1s are combined with each other and carbon atoms to which they are bonded. Examples include those similar to the above.

R ¹ is preferably a monovalent organic group having 1 to 20 carbon atoms or a halogen atom, more preferably a trifluoromethyl group, a tetra-butyl group, or a fluorine atom.

s is preferably 0 to 2, more preferably 0 or 1.

t is preferably 0 to 2, more preferably 0 or 1, and even more preferably 0.

u is preferably 0 to 2, more preferably 0 or 1, and even more preferably 0.

[Cation (Y)]
Examples of the cation (Y) include cations represented by the following formulas (1-1) to (1-11) (hereinafter also referred to as "cations (Y-1) to (Y-11)"). .

As the cation (Y), cations (Y-1) to (Y-5) are preferred.

[Anion (X-1)]
The anion (X-1) is a sulfonic acid anion represented by the following formula (2-1). When anion (X) is anion (X-1), the [Z] compound functions as a radiation-sensitive acid generator in the radiation-sensitive resin composition. In this case, the radiation-sensitive resin composition may contain an acid generator ([B] acid generator) other than the [Z] compound.

In the above formula (2-1), R ^p1 is a monovalent group containing a ring structure having 5 or more ring members. R ^p2 is a divalent linking group. R ^p3 and R ^p4 are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R ^p5 and R ^p6 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. n ^p1 is an integer from 0 to 10. n ^p2 is an integer from 0 to 10. n ^p3 is an integer from 0 to 10. However, n ^p1 + n ^p2 + n ^p3 is 1 or more and 30 or less. When n ^p1 is 2 or more, a plurality of R ^p2s are the same or different from each other. When n ^p2 is 2 or more, a plurality of R ^p3s are the same or different from each other, and a plurality of R ^p4s are the same or different from each other. When n ^p3 is 2 or more, a plurality of R ^p5s are the same or different from each other, and a plurality of R ^p6s are the same or different from each other.

The monovalent group containing a ring structure with 5 or more ring members represented by R ^p1 includes, for example, a monovalent group containing an alicyclic structure with 5 or more ring members, and an aliphatic heterocyclic structure with 5 or more ring members. Examples include a monovalent group, a monovalent group containing an aromatic carbocyclic structure having 5 or more ring members, and a monovalent group containing an aromatic heterocyclic structure having 5 or more ring members.

Examples of alicyclic structures having 5 or more ring members include monocyclic saturated alicyclic structures such as cyclopentane structure, cyclohexane structure, cycloheptane structure, cyclooctane structure, cyclononane structure, cyclodecane structure, and cyclododecane structure, cyclopentene structure, and cyclohexene structure. Structure, monocyclic unsaturated alicyclic structure such as cycloheptene structure, cyclooctene structure, cyclodecene structure, polycyclic saturated alicyclic structure such as norbornane structure, adamantane structure, tricyclodecane structure, tetracyclododecane structure, norbornene structure, Examples include polycyclic unsaturated alicyclic structures such as tricyclodecene structures.

Examples of aliphatic heterocyclic structures having 5 or more ring members include lactone structures such as hexanolactone structures and norbornane lactone structures, sultone structures such as hexanosultone structures and norbornane sultone structures, oxacycloheptane structures, and oxanorbornane structures. Examples include nitrogen atom-containing heterocyclic structures such as oxygen atom-containing heterocyclic structures, azacyclohexane structures and diazabicyclooctane structures, and sulfur atom-containing heterocyclic structures such as thiacyclohexane structures and thianorbornane structures.

Examples of the aromatic carbocyclic structure having 5 or more ring members include a benzene structure, a naphthalene structure, a phenanthrene structure, an anthracene structure, and the like.

Examples of aromatic heterocyclic structures having 5 or more ring members include oxygen atom-containing heterocyclic structures such as furan structure, pyran structure, benzofuran structure, and benzopyran structure, and nitrogen atom-containing heterocyclic structures such as pyridine structure, pyrimidine structure, and indole structure. Examples include.

The lower limit of the number of ring members in the ring structure of R ^p1 is preferably 6, more preferably 8, even more preferably 9, and particularly preferably 10. The upper limit of the number of ring members is preferably 15, more preferably 14, even more preferably 13, and particularly preferably 12. By setting the number of ring members within the above range, the diffusion length of the acid described above can be further appropriately shortened.

Some or all of the hydrogen atoms included in the ring structure of R ^p1 may be substituted with a substituent. Examples of the above-mentioned substituents include halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom, hydroxy group, carboxy group, cyano group, nitro group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, Examples include acyloxy groups. Among these, hydroxy group is preferred.

R ^p1 is preferably a monovalent group containing an alicyclic structure having 5 or more ring members or a monovalent group containing an aliphatic heterocyclic structure having 5 or more ring members, and a monovalent group containing a polycyclic saturated alicyclic structure. A monovalent group containing an oxygen atom-containing heterocyclic structure, or a monovalent group containing a sulfur atom-containing heterocyclic structure is more preferable.

Examples of the divalent linking group represented by R ^p2 include a carbonyl group, an ether group, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, and a divalent hydrocarbon group. Among these, a carbonyloxy group, a sulfonyl group, an alkanediyl group, or a divalent alicyclic saturated hydrocarbon group is preferred, and a carbonyloxy group is more preferred.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^p3 and R ^p4 include an alkyl group having 1 to 20 carbon atoms. The monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R ^p3 and R ^p4 includes, for example, a fluorinated alkyl group having 1 to 20 carbon atoms. R ^p3 and R ^p4 are preferably a hydrogen atom, a fluorine atom or a fluorinated alkyl group, more preferably a fluorine atom or a perfluoroalkyl group, and even more preferably a fluorine atom or a trifluoromethyl group.

The monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R ^p5 and R ^p6 includes, for example, a fluorinated alkyl group having 1 to 20 carbon atoms. As R ^p5 and R ^p6 , a fluorine atom or a fluorinated alkyl group is preferred, a fluorine atom or a perfluoroalkyl group is more preferred, a fluorine atom or a trifluoromethyl group is even more preferred, and a fluorine atom is particularly preferred.

n ^p1 is preferably 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

n ^p2 is preferably 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

The lower limit of n ^p3 is preferably 1, more preferably 2. By setting n ^p3 to 1 or more, the strength of the acid can be increased. The upper limit of n ^p3 is preferably 4, more preferably 3, and even more preferably 2.

The lower limit of n ^p1 +n ^p2 +n ^p3 is preferably 2, and more preferably 4. The upper limit of n ^p1 +n ^p2 +n ^p3 is preferably 20, more preferably 10.

As the anion (X-1), for example, anions represented by the following formulas (2-1-1) to (2-1-12) (hereinafter referred to as "anions (X-1-1) to (X-1- (also referred to as ``12)'').

[Anion (X-2)]
Anion (X-2) is a carboxylic acid anion. When the anion (X) is the anion (X-2), the [Z] compound functions as an acid diffusion control agent in the radiation-sensitive resin composition. In this case, the radiation-sensitive resin composition preferably contains [B] an acid generator. Moreover, in this case, the radiation-sensitive resin composition may contain an acid diffusion control agent ([C] acid diffusion control agent) other than the [Z] compound.

As the anion (X-2), a carboxylic acid anion represented by the following formula (2-2) (hereinafter also referred to as "anion (X-2-1)") is preferable.

In the above formula (2-2), Ar ⁴ is a group obtained by removing hydrogen atoms on (m+n+1) aromatic rings from an arene having 6 to 20 ring members. m is an integer from 0 to 10. When m is 1, R ⁴ is an organic group having 1 to 20 carbon atoms, a nitro group, or a halogen atom. When m is 2 or more, the plurality of R ^4s are the same or different and are an organic group having 1 to 20 carbon atoms, a nitro group, or a halogen atom, or are combined with each other and constituted with the carbon atom to which they are bonded. It is a part of an alicyclic structure having 4 to 20 ring members or an aliphatic heterocyclic structure having 4 to 20 ring members. n is an integer from 1 to 10.

Examples of arenes having 6 to 20 ring members that provide Ar ⁴ include benzene, naphthalene, anthracene, phenanthrene, tetracene, and pyrene. Among these, benzene or naphthalene is preferred, and benzene is more preferred.

Examples of the organic group having 1 to 20 carbon atoms represented by R ⁴ include the same groups as those exemplified as the monovalent organic group having 1 to 20 carbon atoms represented by R ¹² in formula (4) above. can be mentioned.

R ⁴ is preferably an organic group having 1 to 20 carbon atoms, more preferably a trifluoromethyl group.

As n, 1 or 2 is preferable, and 1 is more preferable.

m is preferably 0 to 2, more preferably 0 or 1.

Examples of the anion (X-2) include anions represented by the following formulas (2-2-1) to (2-2-4). Among these, anions represented by the following formulas (2-2-1) and (2-2-2) are preferable examples as anion (X-2-1).

When the [Z] compound functions as a radiation-sensitive acid generator, the lower limit of the content of the [Z] compound in the radiation-sensitive resin composition is 5 parts by mass per 100 parts by mass of the [A] polymer. parts, more preferably 10 parts by weight, and even more preferably 15 parts by weight. The upper limit of the content is preferably 60 parts by mass, more preferably 55 parts by mass, and even more preferably 50 parts by mass. By setting the content of the [Z] compound within the above range, sensitivity to exposure light, LWR performance, and resolution can be further improved.

When the [Z] compound functions as an acid diffusion control agent, the lower limit of the content of the [Z] compound in the radiation-sensitive resin composition is 1 mol% with respect to 100 mol% of the [B] acid generator. is preferable, 5 mol% is more preferable, and even more preferably 10 mol%. The upper limit of the content ratio is preferably 100 mol%, more preferably 50 mol%, and even more preferably 30 mol%. By setting the content ratio of the [Z] compound within the above range, the sensitivity to exposure light, LWR performance, and resolution of the resist pattern formed by the radiation-sensitive resin composition can be further improved.

<[B] Acid generator>
[B] The acid generator is a radiation-sensitive acid generator other than the [Z] compound. [B] The acid generator is a compound that generates acid upon irradiation with radiation. Examples of the radiation include those similar to those exemplified as exposure light in the exposure step of the resist pattern forming method described later. Upon irradiation with radiation, the acid generated from the acid generator [B] dissociates the acid-dissociable groups contained in the structural unit (I) of the polymer [A] to form carboxyl groups, and the exposed and non-exposed areas are separated. A resist pattern can be formed by the difference in solubility of the resist film in the developer between the two. The radiation-sensitive resin composition may contain one or more [B] acid generators.

[B] Examples of the acid generator include triphenylsulfonium salts, diphenyliodonium salts, and compounds described in paragraphs [0080] to [0113] of JP-A No. 2009-134088.

Examples of the triphenylsulfonium salt or diphenyliodonium salt include compounds that are a combination of a triphenylsulfonium cation or diphenyliodonium cation and a sulfonic acid anion exemplified as the anion (X-1) in the [Z] compound.

The lower limit of the content of the acid generator [B] in the radiation-sensitive resin composition is preferably 5 parts by mass, more preferably 10 parts by mass, and 15 parts by mass based on 100 parts by mass of the polymer [A]. is even more preferable. The upper limit of the content is preferably 60 parts by mass, more preferably 55 parts by mass, and even more preferably 50 parts by mass. [B] By setting the content of the acid generator within the above range, sensitivity to exposure light, LWR performance, and resolution can be further improved.

<[C] Acid diffusion control agent>
[C] The acid diffusion control agent is an acid diffusion control agent other than the [Z] compound. [C] Acid diffusion control agent controls the diffusion phenomenon of acid generated from [Z] compound, [B] acid generator, etc. in the resist film upon exposure, and has the effect of controlling undesirable chemical reactions in non-exposed areas. play. By containing the [C] acid diffusion control agent, the radiation-sensitive resin composition can further improve the sensitivity to exposure light, LWR performance, and resolution of the radiation-sensitive resin composition. The radiation-sensitive resin composition may contain one or more [C] acid diffusion control agents.

[C] Examples of the acid diffusion control agent include a nitrogen atom-containing compound, a photodegradable base that generates a weak acid upon exposure to light, and the like.

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, pyridine, Examples include nitrogen-containing heterocyclic compounds such as N-(undecylcarbonyloxyethyl)morpholine and Nt-pentyloxycarbonyl-4-hydroxypiperidine.

Examples of the photodegradable base include compounds containing an onium cation and a weak acid anion that decompose upon exposure to light. In the photodegradable base, a weak acid is generated from protons generated by decomposition of an onium cation and an anion of a weak acid in the exposed area, so that acid diffusion controllability is reduced.

Examples of onium cations that decompose upon exposure include triphenylsulfonium cations, phenyldibenzothiophenium cations, diphenyl(4-fluorophenyl)sulfonium cations, and the like.

Examples of the above-mentioned weak acid anions include those similar to the carboxylic acid anions exemplified as the anion (X-2) in the above-mentioned [Z] compound.

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

The lower limit of the content of the acid diffusion control agent [C] in the radiation-sensitive resin composition is preferably 1 mol%, more preferably 5 mol%, and more preferably 10 mol%, based on 100 mol% of the acid generator [B]. More preferred is mole %. The upper limit of the content is preferably 100 mol%, more preferably 50 mol%, and even more preferably 30 mol%. [C] By setting the content ratio of the acid diffusion control agent within the above range, the sensitivity to exposure light, LWR performance, and resolution of the resist pattern formed by the radiation-sensitive resin composition 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, the [Z] compound, and other optional components contained as necessary.

[D] Examples of the organic solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and hydrocarbon solvents. [D] The organic solvent may contain one type or two or more types.

Examples of alcoholic solvents include aliphatic monoalcohols 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. Examples include solvents, polyhydric alcohol solvents having 2 to 18 carbon atoms such as 1,2-propylene glycol, and partial ether solvents of polyhydric alcohols having 3 to 19 carbon atoms such as propylene glycol-1-monomethyl ether.

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, cyclic ether solvents such as tetrahydrofuran and tetrahydropyran, diphenyl ether, Examples include aromatic ring-containing ether solvents such as anisole.

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

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

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, and propylene acetate. Examples include polyhydric alcohol partial ether carboxylate solvents such as glycol monomethyl ether, polyhydric carboxylic acid diester solvents such as diethyl oxalate, and carbonate solvents such as dimethyl carbonate and diethyl carbonate.

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. It will be done.

[D] As the organic solvent, alcohol solvents and/or ester solvents are preferred, polyhydric alcohol partial ether solvents and/or polyhydric alcohol partial ether carboxylate solvents having 3 to 19 carbon atoms are more preferred, and propylene More preferred are glycol-1-monomethyl ether and/or propylene glycol monomethyl acetate.

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

<Other optional ingredients>
Other optional components include, for example, surfactants. The radiation-sensitive resin composition may contain one or more other optional components.

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

According to the resist pattern forming method, by using the radiation-sensitive resin composition described above as the radiation-sensitive resin composition in the coating step, sensitivity to exposure light is good, and LWR performance and resolution are improved. A resist pattern with excellent properties can be formed.

Each step included in the resist pattern forming method will be described below.

[Coating process]
In this step, a radiation-sensitive resin composition is applied directly or indirectly to the substrate. As a result, a resist film is formed directly or indirectly on the substrate.

In this step, the above-mentioned radiation-sensitive resin composition is used as the radiation-sensitive resin composition.

Examples of the substrate include conventionally known substrates such as silicon wafers, silicon dioxide, and aluminum-coated wafers. In addition, examples of cases in which the radiation-sensitive resin composition is indirectly applied to the substrate include, for example, cases in which the radiation-sensitive resin composition is applied onto an antireflection film formed on the substrate. Examples of such an antireflection film include organic or inorganic antireflection films disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, and the like.

Examples of the coating method include rotation coating (spin coating), casting coating, roll coating, and the like. After coating, if necessary, pre-baking (hereinafter also referred to as "PB") may be performed in order to volatilize the solvent in the coating film. The lower limit of the temperature of PB is preferably 60°C, more preferably 80°C. The upper limit of the above 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 lower limit of the above time is preferably 600 seconds, more preferably 300 seconds. The lower limit of the average thickness of the resist film to be formed is preferably 10 nm, more preferably 20 nm. The upper limit of the average thickness is preferably 1,000 nm, more preferably 500 nm.

[Exposure process]
In this step, the resist film formed in the above coating step is exposed. This exposure is performed by irradiating exposure light through a photomask (in some cases, through an immersion medium such as water). The exposure light can be electromagnetic waves such as visible light, ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays (EUV), X-rays, and γ-rays; charged particles such as electron beams and α-rays, depending on the line width of the target pattern, etc. Examples include lines. Among these, far ultraviolet rays, 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, and ArF excimer laser light , EUV or electron beams are more preferred, and EUV or electron beams are particularly preferred.

After the above-mentioned exposure, a post-exposure bake (hereinafter also referred to as "PEB") is performed, and in the exposed portion of the resist film, [A] polymers etc. are formed by the acid generated from [B] acid generator etc. due to exposure. It is preferable to promote the dissociation of the acid dissociable group. This PEB can increase the difference in solubility in the developer between the exposed area and the non-exposed area. The lower limit of the temperature of PEB is preferably 50°C, more preferably 80°C, and even more preferably 100°C. The upper limit of the above 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 even more preferably 30 seconds. The upper limit of the above time is preferably 600 seconds, more preferably 300 seconds, and even more preferably 100 seconds.

[Development process]
In this step, the exposed resist film is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with a rinsing liquid such as water or alcohol and dry. The developing method in the developing step may be alkaline development or organic solvent development.

In the case of alkaline development, the developer used for development includes, for example, 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] Examples include aqueous alkaline solutions in which at least one alkaline compound such as -7-undecene and 1,5-diazabicyclo-[4.3.0]-5-nonene is dissolved. 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 solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, and solutions containing the above organic solvents. Examples of the organic solvent include one or more of the solvents exemplified as the organic solvent [D] in the radiation-sensitive resin composition described above. Among these, ester solvents or ketone solvents are preferred. As the ester solvent, an acetate ester solvent is preferred, and n-butyl acetate is more preferred. As the ketone solvent, chain ketones are 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, even more preferably 95% by mass, and particularly preferably 99% by mass. Examples of components other than the organic solvent in the developer include water, silicone oil, and the like.

Development methods include, for example, a method in which the substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and the substrate is left stationary for a certain period of time (paddle method). ), a method in which the developer is sprayed onto the surface of the substrate (spray method), and a method in which the developer is continuously applied while scanning the developer application nozzle at a constant speed onto a rotating substrate (dynamic dispensing method). etc.

Examples of patterns formed by the resist pattern forming method include line and space patterns, hole patterns, and the like.

<Compound>
The compound is described as the [Z] compound in the radiation-sensitive resin composition described above. The compound can be suitably used as a radiation-sensitive acid generator or an acid diffusion control agent in a radiation-sensitive resin composition depending on the type of anion contained in the compound.

Hereinafter, the present invention will be specifically explained based on Examples, but the present invention is not limited to these Examples. The method for measuring each physical property value is shown below.

[Weight average molecular weight (Mw), number average molecular weight (Mn) and dispersity (Mw/Mn)]
The Mw and Mn of the polymer were determined by gel permeation chromatography (GPC) using Tosoh Corporation's GPC columns (2 "G2000HXL", 1 "G3000HXL" and 1 "G4000HXL") under the following conditions. It was measured by
Elution solvent: Tetrahydrofuran Flow rate: 1.0mL/min Sample concentration: 1.0% by mass
Sample injection volume: 100μL
Column temperature: 40℃
Detector: Differential refractometer Standard material: Monodisperse polystyrene

[Content ratio of structural units]
The content ratio of each structural unit in the polymer was measured by ¹³ C-NMR analysis using a nuclear magnetic resonance apparatus (JNM-Delta400, manufactured by JEOL Ltd.).

<[A] Synthesis of polymer>
Monomers represented by the following formulas (M-1) to (M-11) (hereinafter also referred to as "monomers (M-1) to (M-11)") are used to synthesize [A] polymer. It was used for. 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 "mol%" means the value when the total number of moles of the monomers used is 100 parts by mass. Means the value expressed as mol%.

[Synthesis Example 1] Synthesis of Polymer (A-1) Monomer (M-1) and monomer (M-3) were mixed with 1-methoxy-2-propanol (1-methoxy-2-propanol) in a molar ratio of 40/60. 200 parts by mass). Next, 6 mol% of azobisisobutyronitrile was added as an initiator to prepare a monomer solution. Meanwhile, 1-methoxy-2-propanol (100 parts by mass) was added to an empty reaction vessel, and the mixture was 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 an additional 3 hours to carry out the polymerization reaction for a total of 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to room temperature.

The cooled polymerization solution was poured into hexane (500 parts by mass based on the polymerization solution), and the precipitated white powder was filtered out. The filtered white powder was washed twice with 100 parts by mass of hexane based on the polymerization solution, filtered, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass) and ultrapure water (10 parts by mass) were added, and a hydrolysis reaction was carried out at 70° C. for 6 hours with stirring. After the hydrolysis reaction was completed, the remaining solvent was distilled off, and the obtained solid was dissolved in acetone (100 parts by mass). The resin was solidified by dropping it into 500 parts by mass of water, and the resulting solid was filtered out. 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. Furthermore, as a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from monomer (M-1) and monomer (M-3) in polymer (A-1) was 41.2 mol each. % and 58.8 mol%.

[Synthesis Examples 2 to 9] Synthesis of Polymers (A-2) to (A-9) Polymers were synthesized in the same manner as Synthesis Example 1, except that the types and proportions of monomers shown in Table 1 below were used. Combined compounds (A-2) to (A-9) were synthesized.

<Synthesis of [Z] compound>
[Synthesis Example 10] Synthesis of Compound (Z-1) 22.0 mmol of the compound represented by the following formula (P-1), 20.0 mmol of the compound represented by the following formula (P-2), and copper acetate were placed in a reaction vessel. (II) 1.0 mmol was mixed and heated and stirred at 130° C. for 30 minutes. After cooling to room temperature, dichloromethane and water were added and the organic layer was separated. The obtained organic layer was washed with water. After drying with sodium sulfate, the solvent was distilled off and purified by silica gel column chromatography to obtain a compound represented by the following formula (P-3) (hereinafter also referred to as "compound (P-3)"). (Yield 55%). The synthesis scheme of compound (P-3) is shown below.

Next, a salt exchange reaction was performed. The specific operating method is as follows. In a reaction vessel, 5.0 mmol of compound (P-3), 5.0 mmol of a compound represented by the following formula (P-4) (hereinafter also referred to as "compound (P-4)"), 50 g of dichloromethane, and 50 g of ultrapure water. added. After stirring at room temperature for 30 minutes, the organic layer was separated. The obtained organic layer was washed with ultrapure water. After drying with sodium sulfate, the solvent was distilled off and purified by silica gel column chromatography to obtain a compound represented by the following formula (Z-1) (hereinafter also referred to as "compound (Z-1)"). (Yield 90%). The synthesis scheme of compound (Z-1) is shown below.

[Synthesis Examples 11 to 25] Synthesis of compounds (Z-2) to (Z-15) and (cz-1) In the same manner as the salt exchange reaction of Synthesis Example 10 except that the precursor was appropriately selected, the following formula Compounds represented by (Z-2) to (Z-15) and (cz-1) (hereinafter referred to as "compounds (Z-2) to (Z-15) and (cz-1)") were synthesized.

[Synthesis Example 26] Synthesis of Compound (Z-16) In the same manner as the salt exchange reaction of Synthesis Example 10, except that sodium 4-(trifluoromethyl)salicylate was used instead of Compound (P-4), A compound represented by the following formula (Z-16) (hereinafter also referred to as "compound (Z-16)") was synthesized.

<Preparation of radiation-sensitive resin composition>
The [B] acid generator, [C] acid diffusion control agent, and [D] organic solvent used in the preparation of the radiation-sensitive resin composition are shown below. In addition, in the following Examples and Comparative Examples, unless otherwise specified, parts by mass mean the values when the mass of the [A] polymer used is 100 parts by mass, and mol % means the value when the mass of the [B] polymer used is 100 parts by mass. It means the value when the number of moles of the acid generator is 100 mol%.

[[B] Acid generator]
[B] As the acid generator, the compounds (Z-1) to (Z-15) and (cz-1) synthesized above were used.

[[C] Acid diffusion control agent]
[C] As the acid diffusion control agent, the compound (Z-16) synthesized above and the compounds represented by the following formulas (C-1) to (C-6) were used.

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

[Example 1] Preparation of radiation-sensitive resin composition (R-1) [A] 100 parts by mass of (A-1) as a polymer, [B] 20 parts by mass of (Z-1) as an acid generator , [C] 20 mol% of (C-1) as an acid diffusion inhibitor based on (Z-1), and [D] 4,800 parts by mass of (D-1) as an organic solvent and (D- 2) A radiation-sensitive resin composition (R-1) was prepared by mixing 2,000 parts by mass.

[Examples 2 to 30 and Comparative Example 1] Preparation of radiation-sensitive resin compositions (R-2) to (R-30) and (CR-1) Using each component of the type and content shown in Table 2 below. Radiation-sensitive resin compositions (R-2) to (R-30) and (CR-1) were prepared in the same manner as in Example 1, except for the following.

<Formation of resist pattern>
The above prepared film was applied to the surface of a 12-inch silicon wafer on which a lower layer film ("AL412" manufactured by Brewer Science) with an average thickness of 20 nm was formed using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Ltd.). Each radiation-sensitive resin composition was applied, soft-baked (SB) at 130°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 50 nm. Next, this resist film was irradiated with EUV light using an EUV exposure machine (“NXE3300” manufactured by ASML, NA=0.33, illumination conditions: Conventional s=0.89, mask imecDEFECT32FFR02). After irradiation, the resist film was subjected to post-exposure baking (PEB) at 130° C. for 60 seconds. Next, using a 2.38% by mass TMAH aqueous solution, development was performed at 23° C. for 30 seconds to form a positive 32 nm line-and-space pattern.

<Evaluation>
Regarding each resist pattern formed above, the sensitivity, LWR performance, and resolution of each radiation-sensitive resin composition were evaluated according to the following method. Note that a scanning electron microscope (“CG-4100” manufactured by Hitachi High-Technologies Corporation) was used to measure the length of the resist pattern. The evaluation results are shown in Table 3 below.

[sensitivity]
In forming the resist pattern, the exposure amount for forming a 32 nm line-and-space pattern was defined as the optimum exposure amount, and this optimum exposure amount was defined as Eop (unit: mJ/cm ² ). The sensitivity was determined to be "good" when Eop was 30 mJ/cm ² or less, and "poor" when it exceeded 30 mJ/cm ² .

[LWR performance]
The resist pattern was observed from above using the above scanning electron microscope. The line width was measured at a total of 50 points at arbitrary locations, a 3 sigma value was determined from the distribution of the measured values, and this was defined as LWR (unit: nm). The smaller the value of LWR, the less wobbling the line is, indicating that it is better. The LWR performance was determined to be "good" when the LWR was less than 4.0 nm, and "poor" when it was 4.0 nm or more.

[Resolution]
At the optimum exposure amount above, measure the dimension of the minimum resist pattern that is resolved when changing the size of the mask pattern forming line and space (1L/1S), and calculate this measurement value as the resolution (unit: nm). And so. The smaller the resolution value, the better the ability to form a finer pattern. The resolution was determined to be "good" if the resolution was 25 nm or less, and "poor" if it exceeded 25 nm.

As is clear from the results in Table 3, all of the radiation-sensitive resin compositions of Examples had better sensitivity, LWR performance, and resolution than the radiation-sensitive resin compositions of Comparative Examples.

According to the radiation-sensitive resin composition and resist pattern forming method of the present invention, it is possible to form a resist pattern that has good sensitivity to exposure light and excellent LWR performance and resolution. Therefore, it can be suitably used for forming fine resist patterns in the lithography process of various electronic devices such as semiconductor devices and liquid crystal devices.

Claims (4)

A polymer having a structural unit containing an acid-dissociable group;
A radiation-sensitive resin composition containing a compound represented by the following formula (1).

(In formula (1), Ar ¹ is a group obtained by removing hydrogen atoms on (s+1) aromatic rings from an arene having 6 to 20 ring members. s is an integer from 0 to 11. 1, R ¹ is an organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When s is 2 or more, R ¹ 's are the same or different and have 1 to 20 carbon atoms. 20 organic groups, hydroxy groups, nitro groups, or halogen atoms, or an alicyclic structure with 4 to 20 ring members or an alicyclic structure with 4 to 20 ring members formed by combining these with the carbon atoms to which they are bonded. It is part of a group heterocyclic structure. Ar ² is a group obtained by removing hydrogen atoms on t aromatic rings from an arene having 6 to 20 ring members. t is an integer of 0 to 10. t When is 1, R ² is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When t is 2 or more, R ² are the same or different from each other, A monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or an alicyclic structure having 4 to 20 ring members formed by combining these with the carbon atoms to which they are bonded. It is part of an aliphatic heterocyclic structure having 4 to 20 ring members.Ar ³ is a group obtained by removing hydrogen atoms on u aromatic rings from an arene having 6 to 20 ring members.u is 0 to is an integer of 10. When u is 1, R ³ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When u is 2 or more, multiple R ³ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or a 4-membered ring formed by combining these together with the carbon atom to which they are bonded. It is a part of an alicyclic structure having ~20 members or an aliphatic heterocyclic structure having 4 to 20 ring members.However, at least one of the arenes providing Ar ² and Ar ³ is a polycyclic arene ^. It is a sulfonic acid anion represented by the following formula (2-1) or a carboxylic acid anion represented by the following formula (2-2) .)

(In formula (2-1), R ^p1 is a monovalent group containing a ring structure with 5 or more ring members. R ^p2 is a divalent linking group. R ^p3 and R ^p4 are each independently and is a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms.R ^p5 and R ^p6 are each independently , a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. n ^p1 is an integer of 0 to 10. n ^p2 is an integer of 0 to 10. n ^p3 is 0 is an integer of ~10. However, n ^p1 + n ^p2 + n ^p3 is 1 or more and 30 or less. When n ^p1 is 2 or more, the plurality of R ^p2s are the same or different from each other. When n ^p2 is 2 or more, A plurality of R ^p3s are the same or different from each other, and a plurality of R ^p4s are the same or different from each other. When n ^p3 is 2 or more, a plurality of R ^p5s are the same or different from each other, and a plurality of R ^p6s are the same or different from each other.)

(In formula (2-2), Ar ⁴ is a group obtained by removing hydrogen atoms on (m+n+1) aromatic rings from an arene having 6 to 20 ring members. m is an integer of 0 to 10. When m is 1, R ⁴ is an organic group having 1 to 20 carbon atoms, a nitro group, or a halogen atom. When m is 2 or more, multiple R ^4s are the same or different and have 1 to 20 carbon atoms. an organic group, a nitro group, or a halogen atom, or an alicyclic structure having 4 to 20 ring members or an aliphatic heterocyclic structure having 4 to 20 ring members, which is formed by combining these with the carbon atoms to which they are bonded. (n is an integer from 1 to 10.) The radiation-sensitive resin composition according to claim 1, wherein the arene having 6 to 20 ring members providing Ar ² in the above formula (1) is benzene, and the arene having 6 to 20 ring members providing Ar ³ is naphthalene. Claim 1 or Claim 2 wherein the structural unit is represented by the following formula (3-1A), formula (3-1B), formula (3-1C), formula (3-2A), or formula (3-2B). The radiation-sensitive resin composition described in .

(In formulas (3-1A), (3-1B), (3-1C), (3-2A) and (3-2B), R ^T is each independently a hydrogen atom, a fluorine atom, a methyl group Or a trifluoromethyl group.
In formulas (3-1A) and (3-1B), R ^X is each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^Y and R ^Z are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or the number of ring members formed by combining these groups together with the carbon atoms to which these groups are bonded. It is part of the alicyclic structure of 3 to 20.
In formula (3-1C), R ^A is a hydrogen atom. R ^B and R ^C each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^D is a divalent hydrocarbon group having 1 to 20 carbon atoms that constitutes an unsaturated alicyclic structure having 4 to 20 ring members together with the carbon atoms to which R ^A , R ^B and R ^C are bonded.
In formulas (3-2A) and (3-2B), R ^U and R ^V are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^W is each independently and is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a part of an alicyclic structure having 3 to 20 ring members formed by combining R ^U and R ^V together with the carbon atoms to which they are bonded. or is part of an aliphatic heterocyclic structure having 5 to 20 ring members formed by combining R ^U and R ^W together with the carbon atom to which R ^U is bonded and the oxygen atom to which R ^W is bonded. ) Coating the radiation-sensitive resin composition according to any one of claims 1 to 3 directly or indirectly onto a substrate;
a step of exposing the resist film formed by the above coating step;
A resist pattern forming method comprising : developing the exposed resist film.