JP6171774B2 - Radiation sensitive resin composition, resist pattern forming method and radiation sensitive acid generator - Google Patents

Description

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

  The radiation-sensitive resin composition used for microfabrication by lithography is designed to irradiate the exposed area with charged particle beams such as deep ultraviolet rays such as ArF excimer laser light and KrF excimer laser light, extreme ultraviolet rays (EUV), and electron beams. A chemical reaction using this acid as a catalyst causes a difference in dissolution rate between the exposed portion and the unexposed portion in the developer, thereby forming a resist pattern on the substrate.

  In such a radiation-sensitive resin composition, it is required to improve resolution and rectangularity of the cross-sectional shape of the resist pattern as processing technology becomes finer. In response to this requirement, the types, molecular structures, and the like of polymers, acid generators, and other components contained in the composition have been studied, and further their combinations have been studied in detail (see Patent Documents 1 to 3). .

  The radiation-sensitive resin composition is prepared, for example, by mixing a polymer, an acid generator, a solvent, and other components at a predetermined ratio, and applied to various substrate surfaces such as a silicon wafer. After the composition is applied, a resist film is formed on various substrate surfaces when the solvent is volatilized.

  Here, in the radiation-sensitive resin composition, if the solubility of components such as a polymer and an acid generator in a solvent is insufficient, uneven coating occurs when the composition is applied to various substrate surfaces. Sometimes. When the substrate surface to which the composition is applied becomes large, uneven application tends to occur.

  If uneven application of the radiation-sensitive resin composition occurs, a resist pattern having desired performance (for example, LWR and resolution) may not be obtained. Among the components contained in the composition, many of the compounds conventionally used as acid generators are inadequately soluble in the solvent that disperses and dissolves the components of the composition, and are soluble in the solvent. There is a need to improve the performance.

Japanese Patent Laid-Open No. 11-125907 Japanese Patent Laid-Open No. 08-146610 JP 2000-298347 A

  The present invention has been completed based on the above circumstances, and an acid generator having high solubility in a solvent, and a radiation sensitive resin having improved LWR and resolution by including the acid generator. An object is to provide a composition.

    In order to solve the above problems, the present invention provides at least one radiation-sensitive acid selected from a polymer having a structural unit containing an acid-dissociable group and an onium salt compound having a cation represented by the following formula (1). A radiation-sensitive resin composition comprising a generator.

[式（１）中、Ｘは硫黄原子またはヨウ素原子であり、Ｙは（１＋ａ）価の芳香環含有基、ＡおよびＢは、それぞれ独立に酸素原子、硫黄原子または窒素原子である。Ｒ^１およびＲ^２は、それぞれ独立に１価の有機基であり、Ｒ^３は水素原子または１価の有機基であり、Ｒ^４は単結合または２価の有機基であって、Ｒ^１、Ｒ^２、Ｒ^３およびＲ^４は、いずれか２つが互いに連結してそれぞれが結合しているＡ、Ｂまたは炭素原子と共に環を形成していてもよい。Ｒ^５は１価の有機基であって、複数存在する場合は互いに連結してＸと共に環を形成していてもよい。ａは１〜５の整数であり、ｂは１〜３の整数であり、ｃは０〜２の整数である。但し、Ｘが硫黄原子の場合はｂ＋ｃ＝３であり、Ｘがヨウ素原子の場合はｂ＋ｃ＝２である。]

[In Formula (1), X is a sulfur atom or an iodine atom, Y is a (1 + a) -valent aromatic ring-containing group, and A and B are each independently an oxygen atom, a sulfur atom, or a nitrogen atom. R ¹ and R ² are each independently a monovalent organic group, R ³ is a hydrogen atom or a monovalent organic group, R ⁴ is a single bond or a divalent organic group, R ¹ , R ² , R ³ and R ⁴ may be linked to each other to form a ring together with A, B or carbon atom to which each is bonded. R ⁵ is a monovalent organic group, and when a plurality of R ⁵ are present, they may be linked together to form a ring with X. a is an integer of 1 to 5, b is an integer of 1 to 3, and c is an integer of 0 to 2. However, when X is a sulfur atom, b + c = 3, and when X is an iodine atom, b + c = 2. ]

  It is preferable that the radiation sensitive resin composition further includes a solvent containing 50% by mass or more of propylene glycol monomethyl ether acetate (PGMEA).

  Moreover, this invention is a resist pattern formation method which has the process of forming a resist film using the said radiation sensitive resin composition, the process of exposing the said resist film, and the process of developing the said exposed resist film. .

  Moreover, this invention is a 1 or more types of radiation sensitive acid generator chosen from the onium salt compound which has a cation represented by following formula (1).

[式（１）中、Ｘは硫黄原子またはヨウ素原子であり、Ｙは（１＋ａ）価の芳香環含有基、ＡおよびＢは、それぞれ独立に酸素原子、硫黄原子または窒素原子である。Ｒ^１およびＲ^２は、それぞれ独立に１価の有機基であり、Ｒ^３は水素原子または１価の有機基であり、Ｒ^４は単結合または２価の有機基であって、Ｒ^１、Ｒ^２、Ｒ^３およびＲ^４は、いずれか２つが互いに連結して、それぞれが結合しているＡ、Ｂまたは炭素原子と共に環を形成していてもよい。Ｒ^５は１価の有機基であって、複数存在する場合は互いに連結してＸと共に環を形成していてもよい。ａは１〜５の整数であり、ｂは１〜３の整数であり、ｃは０〜２の整数である。但し、Ｘが硫黄原子の場合はｂ＋ｃ＝３であり、Ｘがヨウ素原子の場合はｂ＋ｃ＝２である。]

[In Formula (1), X is a sulfur atom or an iodine atom, Y is a (1 + a) -valent aromatic ring-containing group, and A and B are each independently an oxygen atom, a sulfur atom, or a nitrogen atom. R ¹ and R ² are each independently a monovalent organic group, R ³ is a hydrogen atom or a monovalent organic group, R ⁴ is a single bond or a divalent organic group, R ¹ , Any ^{two of} R ² , R ³ and R ⁴ may be connected to each other to form a ring together with A, B or carbon atom to which each is bonded. R ⁵ is a monovalent organic group, and when a plurality of R ⁵ are present, they may be linked together to form a ring with X. a is an integer of 1 to 5, b is an integer of 1 to 3, and c is an integer of 0 to 2. However, when X is a sulfur atom, b + c = 3, and when X is an iodine atom, b + c = 2. ]

In the present invention, the radiation-sensitive acid generator is at least one selected from onium salt compounds having a cation represented by the above formula (1), and the compound has high solubility in a solvent. Therefore, according to the present invention, an acid generator having high solubility in a solvent can be provided. Moreover, according to this invention, the radiation sensitive resin composition which suppressed the coating nonuniformity and improved LWR and the resolution can be provided by including the acid generator with high solubility to the said solvent.

By the way, as a method for improving the solubility of the acid generator, there is a method of introducing an alkyl group into the cation part of the compound used as the acid generator (see Japanese Patent No. 4421707). In the present invention, an acetal structure is used. In addition to improving solubility, it also provides dissolution contrast.
In the present invention, when the acid generator is in a cationic state (mainly unexposed areas), the acetal structure is stable, and therefore the acetal structure is not decomposed even if an acid is generated. This is because the acetal that is electron-attracted by the central S ⁺ (or I ⁺ ) is stable in the cationic state. On the other hand, when the cation is decomposed by light, a diaryl sulfide structure is formed. In this case, the central S atom (or I atom) is a strong electron donating group. Then, the acetal becomes unstable and is decomposed by the surrounding acid to generate an aldehyde structure or a ketone structure. Due to the polar structure of the aldehyde structure or ketone structure-containing diaryl sulfide generated in the exposed area, the alkali development (positive type) improves the dissolution rate of the exposed area, and in the organic solvent development (negative type), It contributes to lowering the dissolution rate, and as a result, the dissolution contrast is increased, leading to improved lithographic performance. Such switching of the dissolution rate of the PAG cation by light is impossible simply by introducing an alkyl group into the cation moiety.

The present invention preferably has the following configuration.
In the onium salt compound having a cation represented by the above formula (1), a compound in which R ⁴ in the above formula (1) is a single bond is preferable.

  In the onium salt compound having a cation represented by the above formula (1), a compound in which A and B in the above formula (1) are oxygen atoms is preferable.

  The onium salt compound having a cation represented by the above formula (1) is a cation represented by the following formula (1-1), a cation represented by the following formula (1-2), and the following formula (1-3). It is preferable that it is an onium salt compound which has at least 1 type of cation chosen from the cation represented by these.

[式（１−１）〜（１−３）中、Ｒ^１およびＲ^２は、それぞれ独立に１価の有機基であり、互いに連結してそれぞれが結合している酸素原子と共に環を形成していてもよい。Ｒ^３１は、炭素数１〜６のアルキル基であり、Ｒは、それぞれ独立して、アルキル基、アルコキシ基、ヒドロキシ基又はハロゲン原子である。ｂ１は１〜３の整数であり、ｃ１は０〜２の整数である。但し、ｂ１＋ｃ１＝３である。ｂ２は１または２であり、ｃ２は０または１である。但し、ｂ２＋ｃ２＝２である。ｄ１、ｄ２およびｈは、それぞれ独立に０〜４の整数であり、ｅ１およびｅ２は、それぞれ独立に０〜５の整数であり、ｆは０〜６の整数である。]

[In Formulas (1-1) to (1-3), R ¹ and R ² are each independently a monovalent organic group, and are linked to each other to form a ring together with the oxygen atoms to which they are bonded. It may be. R ³¹ is an alkyl group having 1 to 6 carbon atoms, and each R is independently an alkyl group, an alkoxy group, a hydroxy group, or a halogen atom. b1 is an integer of 1 to 3, and c1 is an integer of 0 to 2. However, b1 + c1 = 3. b2 is 1 or 2, and c2 is 0 or 1. However, b2 + c2 = 2. d1, d2 and h are each independently an integer of 0 to 4, e1 and e2 are each independently an integer of 0 to 5, and f is an integer of 0 to 6. ]

  According to the radiation-sensitive resin composition, resist pattern forming method, and radiation-sensitive acid generator of the present invention, the radiation-sensitive resin having improved LWR and resolution by including an acid generator having high solubility in a solvent. A composition can be provided. In addition, according to the present invention, by introducing an acetal structure, dissolution contrast can be imparted.

<Radiation sensitive resin composition>
The radiation-sensitive resin composition of the present invention includes a polymer having a structural unit containing an acid-dissociable group (hereinafter also referred to as [A] polymer) and an onium salt having a cation represented by the above formula (1). One or more radiation-sensitive acid generators (hereinafter also referred to as [B] acid generators) selected from compounds.
Further, the radiation sensitive resin composition contains [C] acid diffusion controller, [D] other acid generator, [E] fluorine atom-containing polymer, [F] solvent and [G] uneven distribution accelerator. And may contain other optional components as long as the effects of the present invention are not impaired. Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer is a polymer having the structural unit (I). According to the radiation-sensitive resin composition, the acid-dissociable group of the [A] polymer in the exposed area is dissociated by irradiation with radiation, resulting in a difference in solubility in the developer between the exposed area and the unexposed area. As a result, a resist pattern can be formed. The “acid-dissociable group” refers to a group that replaces a hydrogen atom such as a carboxy group or a hydroxy group and dissociates by the action of an acid. [A] The polymer is not particularly limited as long as it contains an acid-dissociable group, and may be present anywhere in the main chain, side chain, terminal and the like. [A] The polymer includes, in addition to the structural unit (I), a structural unit (II) containing a non-dissociable and polar group, a structural unit (III) represented by the following formula (4), and You may have other structural units other than the said structural units (I)-(III). [A] The polymer may have one or more of each structural unit. Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is a structural unit containing an acid dissociable group. Examples of the structural unit (I) include a structural unit represented by the following formula (2-1) (hereinafter, also referred to as “structural unit (I-1)”), and a structural unit (2-2). And a structural unit (hereinafter also referred to as “structural unit (I-2)”).

In the above formula (2-1), Q ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Y ¹ is a monovalent acid dissociable group.
In the formula (2-2), ^{Q 2} is a hydrogen atom or a methyl group. Y ² is a monovalent acid dissociable group.

Q ¹ is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoint of the copolymerizability of the monomer that gives the structural unit (I-1).

The monovalent acid-dissociable group represented by Y ^1, preferably a group represented by the following formula (Y-1).

In the above formula (Y-1), R ^e1 is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or an alicyclic hydrocarbon group having 3 to 20 carbon atoms. Or R ^e2 and ^{R e3} is independently a monovalent alicyclic hydrocarbon group having a monovalent chain hydrocarbon group or a 3 to 20 carbon atoms having 1 to 10 carbon atoms, or ^{R e2} and R ^e3 represents an alicyclic structure having 3 to 20 ring carbon atoms that is configured together with the carbon atoms to which they are bonded to each other.

Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by R ^e1 , R ^e2 and R ^e3 include, for example,
Alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl and n-pentyl;
Alkenyl groups such as ethenyl group, propenyl group, butenyl group, pentenyl group;
Examples include alkynyl groups such as ethynyl group, propynyl group, butynyl group, and pentynyl group.
Among these, an alkyl group is preferable, an alkyl group having 1 to 4 carbon atoms is preferable, a methyl group, an ethyl group, and an i-propyl group are more preferable, and an ethyl group is particularly preferable.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ^e1 , R ^e2 and R ^e3 include, for example,
A monocyclic cycloalkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group and a tetracyclododecyl group; a monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group and a cyclohexenyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a tricyclodecenyl group.
Among these, a monocyclic cycloalkyl group and a polycyclic cycloalkyl group are preferable, and a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group are more preferable.

Examples of the alicyclic structure having 3 to 20 ring carbon atoms configured together with the carbon atom to which these groups are combined with each other are as follows:
Monocyclic cycloalkane structures such as cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cyclooctane structure;
Polycyclic cycloalkane structures such as norbornane structure, adamantane structure, tricyclodecane structure and tetracyclododecane structure;
Monocyclic cycloalkene structures such as cyclopropene structure, cyclobutene structure, cyclopentene structure, cyclohexene structure, cyclooctene structure;
Examples thereof include polycyclic cycloalkene structures such as a norbornene structure, a tricyclodecene structure, and a tetracyclododecene structure.
Among these, a monocyclic cycloalkane structure and a polycyclic cycloalkane structure are preferable, a monocyclic cycloalkane structure having 5 to 8 carbon atoms, and a polycyclic cycloalkane structure having 7 to 12 carbon atoms are more preferable, A cyclopentane structure, a cyclohexane structure, a cyclooctane structure, a norbornane structure, and an adamantane structure are more preferable, and a cyclopentane structure and an adamantane structure are particularly preferable.
The alicyclic structure may have a substituent. Examples of the substituent include a hydroxy group, a carboxy group, and a cyano group.

The group represented by the formula (Y-1) is a carbon in which R ^e1 is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, and R ^e2 and R ^e3 are combined with each other. It is preferable to represent an alicyclic structure having 3 to 20 ring carbon atoms that is formed together with atoms, R ^e1 is an alkyl group having 1 to 10 carbon atoms, and R ^e2 and R ^e3 are combined with each other and bonded to each other It is more preferable to represent a cycloalkane structure having 3 to 20 ring carbon atoms constituted with atoms, R ^e1 is an alkyl group having 1 to 4 carbon atoms, and R ^e2 and R ^e3 are combined with each other and bonded to each other. More preferably, it represents a monocyclic cycloalkane structure having 5 to 8 ring carbon atoms or a polycyclic cycloalkane structure having 7 to 12 ring carbon atoms, which is constituted with carbon atoms, and 1-ethyl-1-cyclopentyl. , 2-ethyl-2-adamantyl group is particularly preferred.

Q ² is preferably a hydrogen atom from the viewpoint of the copolymerizability of the monomer that gives the structural unit (I-2).

The monovalent acid-dissociable group represented by Y ^2, preferably a group represented by the following formula (Y-2).

In the above formula (Y-2), R ^e4 , R ^e5 and R ^e6 are each independently a hydrogen atom, a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, or a monovalent group having 3 to 20 carbon atoms. Or an alicyclic hydrocarbon group having 1 to 20 carbon atoms or an oxyalicyclic hydrocarbon group having 1 to 20 carbon atoms. However, R ^e4 , R ^e5 and R ^e6 are not simultaneously hydrogen atoms.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by R ^e4 , R ^e5 and R ^e6 include, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n- Alkyl groups such as butyl group, i-butyl group, sec-butyl group, t-butyl group, n-pentyl group; alkenyl groups such as ethenyl group, propenyl group, butenyl group, pentenyl group; ethynyl group, propynyl group, butynyl And alkynyl groups such as a pentynyl group.
Among these, an alkyl group is preferable, an alkyl group having 1 to 4 carbon atoms is preferable, a methyl group, an ethyl group, and an n-propyl group are more preferable, and a methyl group is particularly preferable.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ^e4 , R ^e5 and R ^e6 include the same groups as those exemplified as R ^e1 , R ^e2 and R ^e3. Etc.
Among these, a monocyclic cycloalkyl group and a polycyclic cycloalkyl group are preferable, and a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group are more preferable.

Examples of the monovalent oxy chain hydrocarbon group having 1 to 20 carbon atoms represented by the above R ^e4 , R ^e5 and R ^e6 include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, n Alkoxy groups such as butoxy, i-butoxy, sec-butoxy, t-butoxy and n-pentyloxy; alkenyloxy such as ethenyloxy, propenyloxy, butenyloxy and pentenyloxy; ethynyloxy And alkynyloxy groups such as a propynyloxy group, a butynyloxy group, and a pentynyloxy group.
Among these, an alkoxy group is preferable, an alkoxy group having 1 to 4 carbon atoms is preferable, and a methoxy group, an ethoxy group, and an n-propoxy group are more preferable.

Examples of the monovalent oxyalicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ^e4 , R ^e5 and R ^e6 include, for example, a cyclopropyloxy group, a cyclobutyloxy group, a cyclopentyloxy group, and cyclohexyloxy. Groups, monocyclic cycloalkyloxy groups such as cyclooctyloxy group; polycyclic cycloalkyloxy groups such as norbornyloxy group, adamantyloxy group, tricyclodecyloxy group, tetracyclododecyloxy group; cyclopropenyloxy Groups, cyclobutenyloxy groups, cyclopentenyloxy groups, monocyclic cycloalkenyloxy groups such as cyclohexenyloxy groups; polycyclic cycloalkenyloxy groups such as norbornenyloxy groups and tricyclodecenyloxy groups, etc. Is mentioned.
Among these, a monocyclic cycloalkyloxy group and a polycyclic cycloalkyloxy group are preferable, and a cyclopentyloxy group, a cyclohexyloxy group, a norbornyloxy group, and an adamantyloxy group are more preferable.

Examples of the group represented by the formula (Y-2) include a group in which R ^e4 , R ^e5 and R ^e6 are monovalent chain hydrocarbon groups, and R ^e4 and R ^e5 are monovalent chain hydrocarbon groups. And R ^e6 is a monovalent oxy chain hydrocarbon group, R ^e4 is a monovalent chain hydrocarbon group, and R ^e5 and R ^e6 are monovalent oxy chain hydrocarbon groups, A group in which R ^e4 , R ^e5 and R ^e6 are alkyl groups, a group in which R ^e4 and R ^e5 are alkyl groups and R ^e6 is an alkoxy group, a group in which R ^e4 is an alkyl group and R ^e5 and R ^e6 are alkoxy groups ^Are more preferable, R ^e4 , R ^e5 and R ^e6 are more preferably an alkyl group, and a t-butyl group, a t-pentyl group, a t-hexyl group, and a t-heptyl group are particularly preferable.

  Examples of the structural unit (I) include the structural units represented by the following formulas (2-1-1) to (2-1-7) as the structural unit (I-1); Examples of 2) include structural units represented by the following formulas (2-2-1) to (2-2-3).

In the above formulas (2-1-1) to (2-1-7), Q ¹ has the same meaning as the above formula (2-1). R ^e1 , R ^e2 and R ^e3 have the same ^{meaning as} in the above formula (Y-1). Each r is independently an integer of 1 to 3.
In the above formulas (2-2-1) to (2-2-3), Q ² has the same meaning as the above formula (2-2).

  As the structural unit (I), the structural unit (I-1) is preferable, and the structural unit represented by the formula (2-1-2) and the structural unit represented by the formula (2-1-3) are More preferably, a group containing a cyclopentane structure or a group containing an adamantane structure is more preferred, a structural unit derived from 1-ethyl-1-cyclopentyl (meth) acrylate, or derived from 2-ethyl-2-adamantyl (meth) acrylate. Structural units are particularly preferred.

  As a content rate of structural unit (I), 10 mol%-90 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 20 mol%-70 mol% are more preferable, 30 mol% -60 mol% is more preferable, and 40 mol%-60 mol% is especially preferable. By making the content rate of structural unit (I) into the said range, the LWR performance of the said radiation sensitive resin composition, resolution, the rectangularity of a cross-sectional shape, and a depth of focus can be improved.

[Structural unit (II)]
The structural unit (II) is a structural unit containing a non-dissociable and polar group. When the [A] polymer has the structural unit (II), the dispersibility in the [A] polymer such as the [B] acid generator can be improved. As a result, the radiation sensitive resin composition can improve the LWR performance, resolution, rectangularity of the cross-sectional shape, and depth of focus. Moreover, the adhesiveness to the board | substrate of the resist pattern formed from the said radiation sensitive resin composition can be improved. As the structural unit (II), for example, a structural unit represented by the following formula (3-1) (hereinafter, also referred to as “structural unit (II-1)”), and represented by the following formula (3-2) A structural unit (hereinafter also referred to as “structural unit (II-2)”).

In the above formula (3-1), ^{Q 3} represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. E ¹ is a single bond, —CO—O—, —CO—NH—, or —CO—O— (CH ₂ ) _i —CO—O—. i is an integer of 1-6. R ^4a is a non-acid dissociable group containing a polar group.
In the formula (3-2), ^{Q 4} is a hydrogen atom or a methyl group. R ^a and R ^b are each independently a hydrogen atom, a fluorine atom, a hydroxy group, or a monovalent organic group. s is an integer of 1 to 3. When s is 2 or more, the plurality of R ^a and R ^b may be the same or different. R ^5a and R ^5b are each independently a hydrogen atom, a fluorine atom, a hydroxy group, or a monovalent organic group.

In the structural unit (II-1), Q ³ is preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (II-1).

E ¹ is preferably —CO—O— from the viewpoint of the copolymerizability of the monomer that gives the structural unit (II-1).

Examples of the polar group in the non-acid dissociable group represented by R ^4a and including a polar group include monovalent groups such as a hydroxy group, a carboxy group, a cyano group, a sulfo group, a mercapto group, and an amino group ( a); a carbonyl group, —O—, —S—, —NR′—, a divalent group (b) formed by combining these, and the like. R ′ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

Examples of the non-acid-dissociable and polar group-containing group represented by R ^{5 ′} include, for example, a part or all of the hydrogen atoms of a monovalent hydrocarbon group having 1 to 20 carbon atoms as the monovalent group. A group substituted with (a), a group having 1 to 20 carbon atoms, a group containing the above divalent group (b) between some or all of the carbon-carbon, 1 to 1 to 20 carbon atoms Groups in which part or all of the hydrogen atoms of the valent hydrocarbon group are substituted with the monovalent group (a) and the divalent group (b) is contained between some or all of the carbon-carbons, etc. Is mentioned.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and carbon. Examples thereof include monovalent aromatic hydrocarbon groups of several 6 to 20.
Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include groups similar to those exemplified as R ^e4 , R ^e5 and R ^e6 in the above formula (2-2).
Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include groups similar to those exemplified as R ^e1 , R ^e2 and R ^e3 in the formula (2-1).
Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl group, tolyl group, xylyl group, mesityl group, naphthyl group, methylnaphthyl group, anthryl group, and methylanthryl group. An aralkyl group such as a benzyl group, a phenethyl group, a naphthylmethyl group, or an anthrylmethyl group;

Examples of R ^{5 ′} include a group having a lactone structure, a group having a cyclic carbonate structure, a group having a sultone structure, and a group having a hydroxy group.

Examples of the group having the lactone structure include a butyrolactone-yl group, a norbornane lactone-yl group, and a 5-oxo-4-oxatricyclo [4.3.1.1 ^3,8 ] undecan-yl group. It is done.
Examples of the group having a cyclic carbonate structure include an ethylene carbonate-ylmethyl group.
Examples of the group having a sultone structure include groups having a sultone structure such as a propane sultone-yl group and a norbornane sultone-yl group.
Examples of the group having a hydroxy group include a hydroxyadamantyl group, a dihydroxyadamantyl group, a trihydroxyadamantyl group, and a hydroxyethyl group.

In the structural unit (II-2), Q ⁴ is preferably a hydrogen atom from the viewpoint of copolymerization of the monomer that gives the structural unit (II-2).

Examples of the monovalent organic group represented by R ^a , R ^b , R ^5a and R ^5b include, for example, a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and a monovalent fat having 3 to 20 carbon atoms. A cyclic hydrocarbon group, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a group in which part or all of the hydrogen atoms of these groups are substituted with a substituent, and between these carbon-carbon groups. , -CO-, -CS-, -O-, -S- or -NR "-, or a group containing a combination of two or more thereof. R" represents a hydrogen atom or carbon. It is a monovalent hydrocarbon group of the number 1-20.

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

  Examples of the structural unit (II) include structural units represented by the following formulas (3-1-1) to (3-1-14) as the structural unit (II-1); structural unit (II-2) Examples include structural units represented by the following formulas (3-2-1) to (3-2-4).

In the above formulas (3-1-1) to (3-1-13), Q ³ has the same meaning as the above formula (3-1).
In the above formulas (3-2-1) and (3-2-2), Q ⁴ has the same meaning as the above formula (3-2).

  Among these, the above formulas (3-1-1) to (3-1-6), (3-1-9), (3-1-13), (3-1-14), (3- The structural unit represented by 2-3) or (3-2-4) is preferable.

  As a content rate of structural unit (II), 0 mol%-90 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 20 mol%-70 mol% are more preferable, 30 mol% -60 mol% is more preferable. By making the content rate of structural unit (II) into the said range, the dispersibility in [A] polymer, such as an [B] acid generator, improves more, As a result, LWR of the said radiation sensitive resin composition concerned Performance such as performance can be further improved.

[Structural unit (III)]
The structural unit (III) is a structural unit represented by the following formula (4). When KrF excimer laser light, EUV, electron beam, or the like is used as the radiation to be irradiated, the radiation sensitive resin composition increases the sensitivity because the polymer [A] has the structural unit (III). Can do.

In the formula (4), ^{R 6} is a hydrogen atom or a methyl group. R ⁷ is a monovalent organic group having 1 to 20 carbon atoms. p is an integer of 0-3. If R ⁷ is plural, a plurality of R ⁷ may be the same or different. q is an integer of 1 to 3. However, p and q satisfy p + q ≦ 5.

R ⁶ is preferably a hydrogen atom from the viewpoint of the copolymerizability of the monomer that gives the structural unit (III).

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ⁷ include a monovalent group represented by R ^a , R ^b , R ^5a and R ^5b in the structural unit (II-2). Examples thereof include the same groups as those exemplified as the organic group. Among these, a monovalent chain hydrocarbon group is preferable, an alkyl group is more preferable, and a methyl group is more preferable.

  As said p, the integer of 0-2 is preferable, 0 or 1 is more preferable, and 0 is further more preferable.

  The q is preferably 1 or 2, and more preferably 1.

  Examples of the structural unit (III) include structural units represented by the following formulas (4-1) to (4-4).

In the above formulas (4-1) to (4-4), R ⁶ has the same meaning as in the above formula (4).

  Among these, the structural units represented by the above formulas (4-1) and (4-2) are preferable, and the structural unit represented by the above formula (4-1) is more preferable.

  As a content rate of structural unit (III), 0 mol%-90 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 30 mol%-80 mol% are more preferable, 50 mol% More preferred is ˜75 mol%. By making the content rate of structural unit (III) into the said range, the sensitivity of the said radiation sensitive resin composition can be improved more.

  The structural unit (III) is obtained by polymerizing a monomer in which the hydrogen atom of hydroxystyrene is substituted with a t-butyl group and the like, and then subjecting the obtained polymer to a hydrolysis reaction in the presence of an amine. It can be formed by performing etc.

[Other structural units]
[A] The polymer may have other structural units other than the structural units (I) to (III). Examples of the other structural unit include a structural unit derived from a (meth) acrylic acid ester containing a non-dissociable monovalent alicyclic hydrocarbon group. As a content rate of another structural unit, 20 mol% or less is preferable with respect to all the structural units which comprise a [A] polymer, and 10 mol% or less is more preferable.

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized according to a conventional method such as radical polymerization. For example, (1) a method in which a solution containing a monomer and a radical initiator is dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction, (2) a solution containing the monomer and radical initiation A solution containing an agent separately from a solution containing a reaction solvent or a monomer, and a polymerization reaction, (3) a plurality of types of solutions containing each monomer, and a radical initiator A solution containing a monomer and a radical initiator in a solvent-free or reaction solvent. It is preferable to synthesize by a polymerization reaction method or the like.

  In addition, when the monomer solution is dropped and reacted with respect to the monomer solution, the monomer amount in the dropped monomer solution is 30 mol with respect to the total amount of monomers used for polymerization. % Or more, more preferably 50 mol% or more, and even more preferably 70 mol% or more.

  What is necessary is just to determine the reaction temperature in these methods suitably with initiator seed | species. Usually, it is 30 degreeC-150 degreeC, 40 degreeC-150 degreeC is preferable, and 50 degreeC-140 degreeC is more preferable. Although dripping time changes with conditions, such as reaction temperature, the kind of initiator, and the monomer made to react, it is 30 minutes-8 hours normally, 45 minutes-6 hours are preferable, and 1 hour-5 hours are more preferable. Also, the total reaction time including the dropping time varies depending on the conditions as in the dropping time, but is usually 30 minutes to 12 hours, preferably 45 minutes to 12 hours, and more preferably 1 to 10 hours.

  Examples of the radical initiator used in the polymerization include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), and 2,2′-azobis. (2-cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate), dimethyl 2,2'-azobis Azo radical initiators such as isobutyrate; peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, and the like. Of these, AIBN and dimethyl 2,2'-azobis (2-methylpropionate) are preferred. In addition, you may use a radical initiator individually or in combination of 2 or more types.

  As a reaction solvent, any solvent other than a solvent that inhibits polymerization (nitrobenzene having a polymerization inhibiting effect, mercapto compound having a chain transfer effect, etc.) and capable of dissolving the monomer may be used. it can. Examples thereof include alcohols, ethers, ketones, amides, esters / lactones, nitriles, and mixed solvents thereof. These solvents may be used alone or in combination of two or more.

  The polymer obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after the polymerization reaction is completed, the polymer is recovered as a powder by introducing the polymerization solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols or alkanes may be used alone or in combination of two or more. In addition to the reprecipitation method, the polymer can be recovered by removing low molecular components such as monomers and oligomers by a liquid separation operation, a column operation, an ultrafiltration operation, or the like.

  [A] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 1,000 to 50,000, more preferably 2,000 to 40,000, and more preferably 3,000 to 3,000. 30,000 is more preferable, and 5,000 to 20,000 is particularly preferable. [A] If the Mw of the polymer is less than the lower limit, the heat resistance of the resist pattern formed from the radiation-sensitive resin composition may be lowered. [A] If the Mw of the polymer exceeds the above upper limit, the developability of the radiation-sensitive resin composition may be deteriorated.

  [A] The ratio (Mw / Mn, dispersity) of Mw to polystyrene-equivalent number average molecular weight (Mn) by GPC of the polymer is preferably 1 to 5, more preferably 1 to 3, and 1 to 2.5. Further preferred.

  [A] The content of the polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 85% by mass or more based on the total solid content in the radiation-sensitive resin composition.

[式（１）中、Ｘは硫黄原子またはヨウ素原子であり、Ｙは（１＋ａ）価の芳香環含有基、ＡおよびＢは、それぞれ独立に酸素原子、硫黄原子または窒素原子である。Ｒ^１およびＲ^２は、それぞれ独立に１価の有機基であり、Ｒ^３は水素原子または１価の有機基であり、Ｒ^４は単結合または２価の有機基であって、Ｒ^１、Ｒ^２、Ｒ^３およびＲ^４は、いずれか２つが互いに連結してそれぞれが結合しているＡ、Ｂまたは炭素原子と共に環を形成していてもよい。Ｒ^５は１価の有機基であって、複数存在する場合は互いに連結してＸと共に環を形成していてもよい。ａは１〜５の整数であり、ｂは１〜３の整数であり、ｃは０〜２の整数である。但し、Ｘが硫黄原子の場合はｂ＋ｃ＝３であり、Ｘがヨウ素原子の場合はｂ＋ｃ＝２である。] <[B] Radiation sensitive acid generator>
[B] The radiation sensitive acid generator ([B] acid generator) is a substance that generates an acid upon exposure. Since the acid-dissociable group of the [A] polymer or the like is dissociated by the generated acid to generate a carboxy group or the like, and the solubility of the [A] polymer in the developer containing the organic solvent is reduced, From the radiation-sensitive resin composition, positive and negative resist patterns can be formed.
[B] The acid generator is composed of one or more compounds selected from onium salt compounds having a cation represented by the following formula (1).

[In Formula (1), X is a sulfur atom or an iodine atom, Y is a (1 + a) -valent aromatic ring-containing group, and A and B are each independently an oxygen atom, a sulfur atom, or a nitrogen atom. R ¹ and R ² are each independently a monovalent organic group, R ³ is a hydrogen atom or a monovalent organic group, R ⁴ is a single bond or a divalent organic group, R ¹ , R ² , R ³ and R ⁴ may be linked to each other to form a ring together with A, B or carbon atom to which each is bonded. R ⁵ is a monovalent organic group, and when a plurality of R ⁵ are present, they may be linked together to form a ring with X. a is an integer of 1 to 5, b is an integer of 1 to 3, and c is an integer of 0 to 2. However, when X is a sulfur atom, b + c = 3, and when X is an iodine atom, b + c = 2. ]

Examples of the aromatic ring-containing group represented by Y in Formula (1) include aryl groups such as phenyl group, tolyl group, xylyl group, mesityl group, naphthyl group, methylnaphthyl group, anthryl group, and methylanthryl group; Examples thereof include a group in which a hydrogen is removed from an aralkyl group such as a benzyl group, a phenethyl group, a naphthylmethyl group, and an anthrylmethyl group.
A and B in formula (1) are each preferably an oxygen atom.

Examples of the monovalent organic group represented by R ¹ , R ² and R ⁵ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, and a sec-butyl group. Alkyl groups having 1 to 6 carbon atoms, such as t-butyl group, n-pentyl group and n-hexyl group;
An alkynyl group having 2 to 5 carbon atoms; an alkynyl group having 2 to 5 carbon atoms; a cycloalkyl group having 3 to 10 carbon atoms such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group and a cyclooctyl group; a norbornyl group and an adamantyl group Bridged alicyclic hydrocarbon group having 7 to 20 carbon atoms such as a group, tricyclodecyl group and tetracyclododecyl group; 3 to 10 carbon atoms such as cyclopropenyl group, cyclobutenyl group, cyclopentenyl group and cyclohexenyl group Cycloalkenyl group; phenyl group, tolyl group, xylyl group, mesityl group, naphthyl group, methylnaphthyl group, anthryl group, methylanthryl group and other aryl groups having 6 to 20 carbon atoms; benzyl group, phenethyl group, naphthylmethyl group And aralkyl groups having 6 to 20 carbon atoms such as anthrylmethyl group, etc. It may have a substituent.
Of these, an alkyl group, a cycloalkyl group, and an aryl group are preferable.

R ³ is a hydrogen atom or a monovalent organic group, and specific examples in the case where R ³ is a monovalent organic group include the same groups as R ¹ and R ² described above. R ³ is preferably an alkyl group, a cycloalkyl group, or an aryl group, more preferably an alkyl group having 1 to 6 carbon atoms, and particularly preferably a methyl group.
R ⁴ is a single bond or a divalent organic group, and specific examples when R ⁴ is a divalent organic group include, for example, an alkanediyl group having 1 to 10 carbon atoms and an arylene group having 6 to 20 carbon atoms. These may be substituted. R ⁴ is preferably a single bond.
When any ^{two of} R ¹ , R ² , R ³ and R ⁴ are connected, the cyclic structure is preferably a hydrocarbon group (an alicyclic hydrocarbon group or an aromatic hydrocarbon group) or a heterocyclic group. .

    As an onium salt compound having a cation represented by the formula (1), a cation represented by the following formula (1-1), a cation represented by the following formula (1-2), and the following formula (1-3) It is preferable that it is an onium salt compound which has at least 1 type of cation chosen from the cation represented by these.

[式（１−１）〜（１−３）中、Ｒ^１およびＲ^２は、それぞれ独立に１価の有機基であり、互いに連結してそれぞれが結合している酸素原子と共に環を形成していてもよい。Ｒ^３１は、炭素数１〜６のアルキル基であり、Ｒは、それぞれ独立して、アルキル基、アルコキシ基、ヒドロキシ基又はハロゲン原子である。ｂ１は１〜３の整数であり、ｃ１は０〜２の整数である。但し、ｂ１＋ｃ１＝３である。ｂ２は１または２であり、ｃ２は０または１である。但し、ｂ２＋ｃ２＝２である。ｄ１、ｄ２およびｈは、それぞれ独立に０〜４の整数であり、ｅ１およびｅ２は、それぞれ独立に０〜５の整数であり、ｆは０〜６の整数である。]

[In Formulas (1-1) to (1-3), R ¹ and R ² are each independently a monovalent organic group, and are linked to each other to form a ring together with the oxygen atoms to which they are bonded. It may be. R ³¹ is an alkyl group having 1 to 6 carbon atoms, and each R is independently an alkyl group, an alkoxy group, a hydroxy group, or a halogen atom. b1 is an integer of 1 to 3, and c1 is an integer of 0 to 2. However, b1 + c1 = 3. b2 is 1 or 2, and c2 is 0 or 1. However, b2 + c2 = 2. d1, d2 and h are each independently an integer of 0 to 4, e1 and e2 are each independently an integer of 0 to 5, and f is an integer of 0 to 6. ]

  Specific examples of the cation represented by the formula (1-1) include cations represented by the following formulas (1-1-1) to (1-1-3), and the formula (1-2) Specific examples of the cation represented by formula (1) include the cation represented by the following formula (1-2-1). Specific examples of the cation represented by formula (1-3) include, for example, the following formula: Examples include cations represented by (1-3-1) to (1-3-2).

  As the onium salt compound having a cation represented by the formula (1), an onium salt compound having an anion represented by the following formula (5) is preferable. When the onium salt compound is a compound having an anion represented by the following formula (5), the diffusion length of the acid generated by exposure in the resist film due to the interaction with the structural unit (I) of the polymer [A] As a result, the above-described LWR performance and the like are improved.

_{^{R 10 -R 11 -SO 3 - (}} 5)

In the above formula (5), R ¹⁰ is a monovalent group containing an alicyclic structure having 6 or more ring members or a monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members. R ¹¹ is a fluorinated alkanediyl group having 1 to 10 carbon atoms.

Examples of the monovalent group containing an alicyclic structure having 6 or more ring members represented by R ¹⁰ include:
A monocyclic cycloalkyl group such as a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cyclododecyl group;
A monocyclic cycloalkenyl group such as a cyclooctenyl group and a cyclodecenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
Examples thereof include polycyclic cycloalkenyl groups such as norbornenyl group and tricyclodecenyl group.

Examples of the monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members represented by R ¹⁰ include:
A group containing a lactone structure such as a norbornanelactone-yl group;
A group containing a sultone structure such as a norbornane sultone-yl group;
An oxygen atom-containing heterocyclic group such as an oxacycloheptyl group and an oxanorbornyl group;
A nitrogen atom-containing heterocyclic group such as an azacyclohexyl group, an azacycloheptyl group, a diazabicyclooctane-yl group;
And sulfur atom-containing heterocyclic groups such as a thiacycloheptyl group and a thianorbornyl group.

The number of ring members of the group represented by R ¹⁰ is preferably 8 or more, more preferably 9 to 15 and even more preferably 10 to 13 from the viewpoint that the diffusion length of the acid described above becomes more appropriate.

R ¹⁰ is, in a range not impairing the effects of the present invention, between a monovalent group containing an alicyclic structure having 6 or more ring members and an aliphatic heterocyclic structure having 6 or more ring members and R ¹¹ , —COO— , —OCO—, —SO ₂ — and the like may be contained.

Among these, R ¹⁰ includes groups represented by the following formulas (5-A) to (5-D) from the viewpoint of further appropriately shortening the diffusion length of the acid generated by exposure in the resist film. preferable.

  In the above formulas (5-A), (5-B), (5-C), and (5-D), each * is a bond.

Examples of the fluorinated alkanediyl group having 1 to 10 carbon atoms represented by R ¹¹ include one or more hydrogen atoms of an alkanediyl group having 1 to 10 carbon atoms such as a methanediyl group, an ethanediyl group, and a propanediyl group. And a group in which is substituted with a fluorine atom.

Among these, as the fluorinated alkanediyl group having 1 to 10 carbon atoms represented by R ¹¹ , an SO ₃ ⁻ group is selected from the viewpoint that the diffusion length of the acid generated by exposure in the resist film is further appropriately shortened. A fluorinated alkanediyl group in which a fluorine atom is bonded to a carbon atom adjacent to, and a fluorinated alkanediyl group in which two fluorine atoms are bonded to a carbon atom adjacent to the SO ₃ ^— group is more preferable, More preferred are 1,1-difluoromethanediyl group, 1,1,2,2,3,3-hexafluoropropanediyl group and 1,1,3,3,3-pentafluoro-1,2-propanediyl group. .

  [B] The content of the acid generator is 0.1 to 30 parts by mass with respect to 100 parts by mass of the polymer [A] from the viewpoint of ensuring the sensitivity and developability of the radiation-sensitive resin composition. Or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, and further preferably 1 part by mass or more and 15 parts by mass or less. Thus, by making content of [B] acid generator into the said range, the sensitivity and developability of the said radiation sensitive resin composition improve.

The radiation sensitive resin composition may contain other acid generators ([D] other acid generators). Examples of such other acid generators include onium salt compounds, N-sulfonyloxyimide compounds, halogen-containing compounds, diazoketone compounds, and the like other than the compounds exemplified for [B] acid generators.
As other onium salt compounds, sulfonium salts and iodonium salts other than those described above are preferably used, and particularly preferably have an anion represented by the above formula (5) and represented by the above formula (1). The compound which has cations other than a cation is mentioned. As the cation in the compound, cations represented by the following formulas (i-1) to (i-3) are preferable.

（上記式（ｉ−１）〜（ｉ−３）中、Ｒは、それぞれ独立して、アルキル基、アルコキシ基、ヒドロキシ基又はハロゲン原子である。ｉ、ｊ、ｋ、ｎおよびｏは、それぞれ独立して、０〜５の整数であり、ｌは０〜７の整数であり、ｍは０〜４の整数である。）
その他のオニウム塩化合物としては、例えば、テトラヒドロチオフェニウム塩、ホスホニウム塩、ジアゾニウム塩、ピリジニウム塩等が挙げられる。

(In the above formulas (i-1) to (i-3), each R is independently an alkyl group, an alkoxy group, a hydroxy group or a halogen atom. I, j, k, n and o are each Independently, it is an integer of 0-5, l is an integer of 0-7, and m is an integer of 0-4.)
Examples of other onium salt compounds include tetrahydrothiophenium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like.

  Examples of the tetrahydrothiophenium salt include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium. Nonafluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothio Phenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphor Sulfonate, 1- (6-n-butoxynaphthalen-2-yl) Tetrahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothio Phenium perfluoro-n-octanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2, 2-tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium camphorsulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (3,5-dimethyl- -Hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl -4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl-4- Hydroxyphenyl) tetrahydrothiophenium camphorsulfonate and the like.

Examples of the N-sulfonyloxyimide compound include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyl). Oxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene- 2,3-dicarboximide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept 5-ene-2,3-dicarboximide, N- (2- (3- tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1 Jifuruoroe Tansulfonylsulfonyl) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3 -Dicarboximide etc. are mentioned.

<[C] Acid diffusion controller>
The radiation sensitive resin composition may contain a [C] acid diffusion controller. [C] The acid nucleic acid controller is a component that controls the diffusion phenomenon of the acid generated from the [B] acid generator and the like in the resist film by exposure and suppresses an undesirable chemical reaction in the unexposed area. Moreover, a change in the line width of the resist pattern due to a change in the holding time from exposure to development processing can be suppressed, and a composition having excellent process stability can be obtained. The radiation-sensitive resin composition can further improve LWR performance, resolution, rectangularity of the cross-sectional shape, and depth of focus by further containing a [C] acid diffusion controller. As the inclusion form of the [C] acid diffusion controller in the radiation sensitive resin composition, a low molecular compound form (hereinafter referred to as “[C] acid diffusion controller” as appropriate) is incorporated as a part of the polymer. Or both of these forms. The radiation sensitive resin composition may contain one or more [C] acid diffusion controllers.

  [C] Examples of the acid diffusion controller include amine compounds, amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

  Examples of the amine compound include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines or derivatives thereof; ethylenediamine, N, N, N ′, N ′. -Tetramethylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylamine, 2,2-bis (4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4 -Aminophenyl) -2- (4-hydroxyphenyl) propane 1,4-bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, bis (2-dimethylamino) Ethyl) ether, bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxalinol, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ) Ethylenediamine, N, N, N ′, N ″ N ″ -pentamethyldiethylenetriamine and the like.

Examples of the amide group-containing compound include:
Nt-butoxycarbonyl group-containing amino compounds such as Nt-butoxycarbonyl-4-hydroxypiperidine;
Nt-amyloxycarbonyl group-containing amino compounds such as Nt-amyloxycarbonyl-4-hydroxypiperidine;
Formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, N-acetyl-1-adamantylamine, isocyanuric Examples include acid tris (2-hydroxyethyl).

  Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, and tri-n-butyl. Examples include thiourea.

  Examples of the nitrogen-containing heterocyclic compound include imidazoles such as 2-phenylimidazole; pyridines; piperazines; pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, piperidineethanol, 3-piperidino-1,2 -Propanediol, morpholine, 4-methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine, 3- (N-morpholino) -1,2-propanediol, 2-morpholinoethyl dodecylate, 1,4 -Dimethyl piperazine, 1, 4-diazabicyclo [2.2.2] octane, etc. are mentioned.

  Of these, 2-morpholinoethyl dodecylate is preferred.

In addition, as the [C] acid diffusion controller, a photodisintegratable base that is exposed to light and generates a weak acid upon exposure can also be used. Examples of the photodegradable base include an onium salt compound that decomposes upon exposure and loses acid diffusion controllability. Examples of the onium salt compound include cations represented by the above formulas (i-1) to (i-3), and include OH ⁻ , R ⁸ —COO ⁻ , R ⁸ —SO ₃ ^—, or the following formula (ii) The compound which has an anion represented by this is mention | raise | lifted. However, R ⁸ is an alkyl group, an aryl group or an aralkyl group.

In said formula (ii), R < ⁹ > is a C1-C12 linear or branched alkyl group by which some or all of the hydrogen atoms may be substituted by the fluorine atom, or C1-C12 These are linear or branched alkoxy groups. k is an integer of 0-2.

  As said other photodegradable base, the compound etc. which are represented by a following formula are mentioned, for example.

  [C] The content of the acid diffusion controller is 30 parts by mass or less with respect to 100 parts by mass of the polymer [A] when the [C] acid diffusion controller is a [C] acid diffusion controller. Preferably, 0.1 mass part-20 mass parts are more preferable, and 0.5 mass part-10 mass parts are further more preferable. [C] By making content of an acid diffusion control agent into the said range, the LWR performance of the said radiation sensitive resin composition etc. can be improved further.

<[E] polymer>
According to the radiation sensitive resin composition, in addition to the [A] polymer, the [E] fluorine atom-containing polymer ([E] polymer) is further contained, so that the surface layer of the resist film to be formed is [E]. The polymer is unevenly distributed, and as a result, the hydrophobicity of the resist film surface can be improved. As a result, when performing immersion exposure, etc., the substance elution suppression from the resist film is excellent, and the receding contact angle between the resist film and the immersion liquid can be sufficiently increased, enabling faster scanning. Become.

  [E] The polymer is not particularly limited as long as it is a polymer containing a fluorine atom. (1) A polymer that is insoluble in a developer and becomes alkali-soluble by the action of an acid; A polymer which is itself soluble in a developer and whose alkali solubility is increased by the action of an acid; (3) a polymer which is itself insoluble in a developer and becomes alkali-soluble by the action of an alkali; (4) itself Is a polymer that is soluble in a developer and whose alkali solubility is increased by the action of an alkali.

[E] As an aspect of the polymer, for example, a structure in which a fluorinated alkyl group is bonded to the main chain;
Examples include a structure in which a fluorinated alkyl group is bonded to the side chain; a structure in which a fluorinated alkyl group is bonded to the main chain and the side chain, and the like.

  Examples of the monomer that gives a structure in which a fluorinated alkyl group is bonded to the main chain include, for example, α-trifluoromethyl acrylate compound, β-trifluoromethyl acrylate compound, α, β-trifluoromethyl acrylate compound, one or more types And compounds in which the hydrogen atom of the vinyl moiety is substituted with a fluorinated alkyl group such as a trifluoromethyl group.

  Examples of monomers that give a structure in which a fluorinated alkyl group is bonded to the side chain include, for example, those in which the side chain of an alicyclic olefin compound such as norbornene is a fluorinated alkyl group or a derivative thereof, acrylic acid or methacrylic acid. Examples include ester compounds in which the side chain is a fluorinated alkyl group or a derivative thereof, and one or more olefin side chains (sites not including a double bond) being a fluorinated alkyl group or a derivative thereof.

  Monomers that give a structure in which a fluorinated alkyl group is bonded to the main chain and side chain include, for example, α-trifluoromethylacrylic acid, β-trifluoromethylacrylic acid, α, β-trifluoromethylacrylic acid. Such as a fluorinated alkyl group or its derivative ester compound, or a compound in which the hydrogen atom of one or more vinyl moieties is substituted with a fluorinated alkyl group such as a trifluoromethyl group, Substituted by the derivative, a hydrogen atom bonded to a double bond of one or more alicyclic olefin compounds is substituted with a fluorinated alkyl group such as a trifluoromethyl group, and the side chain is a fluorinated alkyl group And those which are derivatives thereof. In addition, an alicyclic olefin compound shows the compound in which a part of ring is a double bond.

  [E] The polymer preferably has a structural unit (f1) represented by the following formula (6) and / or a structural unit (f2) represented by the following formula (7). [E] The polymer may have “another structural unit” other than the structural unit (f1) and the structural unit (f2). In addition, the [E] polymer may contain 1 type, or 2 or more types of each structural unit. Hereinafter, each structural unit will be described in detail.

[Structural unit (f1)]
The structural unit (f1) is a structural unit represented by the following formula (6).

In said formula (6), ^Rf1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ^f2 is a C 1-6 linear or branched alkyl group having a fluorine atom or a C 4-20 monovalent alicyclic hydrocarbon group having a fluorine atom. However, one part or all part of the hydrogen atom which the said alkyl group and alicyclic hydrocarbon group have may be substituted.

  As said C1-C6 linear or branched alkyl group, a methyl group, an ethyl group, a propyl group, a butyl group etc. are mentioned, for example.

  Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms include a cyclopentyl group, a cyclopentylpropyl group, a cyclohexyl group, a cyclohexylmethyl group, a cycloheptyl group, a cyclooctyl group, and a cyclooctylmethyl group. It is done.

  Examples of the monomer that gives the structural unit (f1) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, perfluoroethyl (meth) acrylate, and perfluoro n-propyl. (Meth) acrylate, perfluoro i-propyl (meth) acrylate, perfluoro n-butyl (meth) acrylate, perfluoro i-butyl (meth) acrylate, perfluoro t-butyl (meth) acrylate, perfluorocyclohexyl (meta ) Acrylate, 2- (1,1,1,3,3,3-hexafluoro) propyl (meth) acrylate, 1- (2,2,3,3,4,4,5,5-octafluoro) pentyl (Meth) acrylate, 1- (2,2,3,3,4,4,5,5-octafluoro) he Sil (meth) acrylate, perfluorocyclohexylmethyl (meth) acrylate, 1- (2,2,3,3,3-pentafluoro) propyl (meth) acrylate, 1- (2,2,3,3,4,4) 4,4-Heptafluoro) penta (meth) acrylate, 1- (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10- Heptadecafluoro) decyl (meth) acrylate, 1- (5-trifluoromethyl-3,3,4,4,5,6,6,6-octafluoro) hexyl (meth) acrylate and the like.

  As the structural unit (f1), structural units represented by the following formulas (6-1) and (6-2) are preferable.

In the formulas (6-1) and (6-2), R ^f1 has the same ^meaning as the formula (6).

  Among these, the structural unit represented by the formula (6-1) is more preferable.

  As a content rate of a structural unit (f1), 10 mol%-70 mol% are preferable with respect to all the structural units which comprise a [E] polymer, and 20 mol%-50 mol% are more preferable.

[Structural unit (f2)]
The structural unit (f2) is a structural unit represented by the following formula (7).

In the above formula (7), R ^f3 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ^f4 is a (r + 1) -valent linking group. X ¹ is a divalent linking group having a fluorine atom. R ^f5 is a hydrogen atom or a monovalent organic group. r is an integer of 1 to 3. However, when r is 2 or 3, the plurality of X ¹ and R ^f5 may be the same or different.

In the above formula (7), examples of the (r + 1) -valent linking group represented by R ^f4 include a linear or branched hydrocarbon group having 1 to 30 carbon atoms and an alicyclic group having 3 to 30 carbon atoms. One selected from the group consisting of a formula hydrocarbon group, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an oxygen atom, a sulfur atom, an ether group, an ester group, a carbonyl group, an imino group, and an amide group. The group which combined the above group is mentioned. The (r + 1) -valent linking group may have a substituent.

  Examples of the linear or branched hydrocarbon group having 1 to 30 carbon atoms include hydrocarbon groups such as methane, ethane, propane, butane, pentane, hexane, heptane, decane, icosane, and triacontane (r + 1). ) Groups from which a single hydrogen atom is removed.

Examples of the alicyclic hydrocarbon group having 3 to 30 carbon atoms include:
As monocyclic saturated hydrocarbons, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, methylcyclohexane, ethylcyclohexane, etc .;
As monocyclic unsaturated hydrocarbons, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, cyclopentadiene, cyclohexadiene, cyclooctadiene, cyclodecadiene, etc .;
As polycyclic saturated hydrocarbons, bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane, tricyclo [5.2.1.0 ^2,6 ] decane, tricyclo [3.3.1]. ^.1,3,7 ] decane, tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodecane, adamantane, etc .;
As polycyclic unsaturated hydrocarbons, bicyclo [2.2.1] heptene, bicyclo [2.2.2] octene, tricyclo [5.2.1.0 ^2,6 ] decene, tricyclo [3.3. 1.1 ^3,7 ] decene, tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodecene and the like, and (r + 1) hydrogen atoms are removed.

  Examples of the aromatic hydrocarbon group having 6 to 30 carbon atoms include aromatic hydrocarbon groups such as benzene, naphthalene, phenanthrene, anthracene, tetracene, pentacene, pyrene, picene, toluene, xylene, ethylbenzene, mesitylene, cumene, and the like. And groups excluding (r + 1) hydrogen atoms.

In the above formula (7), the divalent linking group having a fluorine atom represented by X ^1, include a divalent linear hydrocarbon group having 1 to 20 carbon atoms having a fluorine atom. Examples of X ¹ include groups represented by the following formulas (X1-1) to (X1-6).

X ¹ is preferably a group represented by the above formulas (X1-1) and (X1-2), more preferably a group represented by the formula (X1-2).

In the above formula (7), examples of the monovalent organic group represented by R ^f5 include a linear or branched hydrocarbon group having 1 to 30 carbon atoms and an alicyclic carbonization having 3 to 30 carbon atoms. One or more selected from the group consisting of a hydrogen group, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an oxygen atom, a sulfur atom, an ether group, an ester group, a carbonyl group, an imino group, and an amide group. Examples include a group combined with a group.

  Examples of the structural unit (f2) include structural units represented by the following formulas (7-1) and (7-2).

In the above formula (7-1), R ^f4 is a divalent linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms. R ^f3 , X ¹ and R ^f5 are synonymous with the above formula (7).

In the above formula (7-2), R ^f3 , X ¹ , R ^f5 and r are as defined in the above formula (7). However, when r is 2 or 3, the plurality of X ¹ and R ^f5 may be the same or different.

  Examples of the structural unit represented by the above formula (7-1) and formula (7-2) include the following formulas (7-1-1) to (7-1-3) and formula (7-2-1). ) And the like.

In the formulas (7-1-1) to (7-1-3) and the formula (7-2-1), R ^f3 has the same meaning as the formula (7).

  As the structural unit (f2), a structural unit represented by the above formula (7-1) is preferable, and a structural unit represented by the above formula (7-1-3) is more preferable.

  Examples of the monomer that gives the structural unit (f2) include (meth) acrylic acid [2- (1-ethyloxycarbonyl-1,1-difluoro-n-butyl)] ester, (meth) acrylic acid (1 , 1,1-trifluoro-2-trifluoromethyl-2-hydroxy-3-propyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4 -Butyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-5-pentyl) ester, (meth) acrylic acid 2-{[5- (1 ' , 1 ′, 1′-trifluoro-2′-trifluoromethyl-2′-hydroxy) propyl] bicyclo [2.2.1] heptyl} ester and the like. Among these, (meth) acrylic acid [2- (1-ethyloxycarbonyl-1,1-difluoro-n-butyl)] ester is preferable.

  As a content rate of a structural unit (f2), 30 mol%-90 mol% are preferable with respect to all the structural units which comprise a [E] polymer, and 50 mol%-80 mol% are more preferable.

[Other structural units]
[E] The polymer may contain “other structural units” other than the structural unit (f1) and the structural unit (f2). Examples of other structural units include the structural unit (I) of [A] polymer.

  As a content rate of another structural unit, 5 mol%-90 mol% are preferable with respect to all the structural units which comprise a [E] polymer, 10 mol%-80 mol% are more preferable, 20 mol%- 70 mol% is more preferable.

  [E] The content of the polymer is preferably 20 parts by mass or less, more preferably 0.1 part by mass to 15 parts by mass with respect to 100 parts by mass of the polymer [A], and 1 part by mass to 10 parts by mass. Is more preferable, and 1 to 6 parts by mass is particularly preferable. [E] When the content of the polymer exceeds the above upper limit, the water repellency of the resist film surface becomes too high and development failure may occur.

[E] The fluorine atom content of the polymer is preferably larger than the fluorine atom content of the [A] polymer. When the fluorine atom content in the [E] polymer is larger than that in the [A] polymer, the repellency of the resist film surface formed by the radiation sensitive resin composition containing the [A] polymer and the [E] polymer is determined. The aqueous property can be further increased. [E] The difference between the fluorine atom content of the polymer and the fluorine atom content of the [A] polymer is preferably 1% by mass or more, and more preferably 3% by mass or more.
[E] The fluorine atom content of the polymer is preferably 1% by mass or more, more preferably 3% by mass or more, further preferably 5% by mass or more, and particularly preferably 10% by mass or more.
The fluorine atom content (% by mass) can be calculated from the structure of the polymer obtained by ¹³ C-NMR.

<[E] Production Method of Polymer>
[E] The polymer can be produced, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable polymerization solvent using a radical polymerization initiator.

  Examples of the radical polymerization initiator include those similar to the radical polymerization initiator used in the method for producing the polymer [A]. As said polymerization solvent, the thing similar to the polymerization solvent used by the manufacturing method of [A] polymer is mentioned, for example.

  As reaction temperature in the said superposition | polymerization, it is 40 to 150 degreeC normally, and 50 to 120 degreeC is preferable. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

  [E] The Mw of the polymer is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, and still more preferably 3,000 to 10,000. [E] When the Mw of the polymer is less than 1,000, a sufficient receding contact angle cannot be obtained. On the other hand, when Mw exceeds 50,000, the developability of the resist tends to decrease.

  [E] As a ratio (Mw / Mn) of Mw and Mn of the polymer, 1 to 5 is preferable, and 1 to 3 is more preferable.

<[F] solvent>
[F] The solvent is a component for dissolving or dispersing the [A] polymer, [B] acid generator, and optional components. [F] Examples of the solvent include alcohol solvents, ketone solvents, amide solvents, ether solvents, ester solvents, and the like. [F] You may use a solvent individually by 1 type or in combination of 2 or more types.

As an alcohol solvent, for example,
Methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec-pentanol, tert- Pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n- Nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, furf Alcohol, phenol, cyclohexanol, methyl cyclohexanol, 3,3,5-trimethyl cyclohexanol, benzyl alcohol, mono-alcohol solvents such as diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 -Polyhydric alcohol solvents such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether solvents such as dipropylene glycol monopropyl ether.

Examples of the ketone solvent include:
Acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-iso- Chain ketone solvents such as butyl ketone, trimethylnonanone, 2,4-pentanedione, acetonyl acetone, diacetone alcohol, acetophenone;
Examples thereof include cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone.

As the amide solvent, for example,
Chain amide solvents such as N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide;
Examples thereof include cyclic amide solvents such as N-methylpyrrolidone and N, N′-dimethylimidazolidinone.

As the ether solvent, for example,
Chain ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, diphenyl ether;
Examples thereof include cyclic ether solvents such as tetrahydrofuran and tetrahydropyran.

As the ester solvent, for example,
Methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate Acetate solvents such as 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, glycol diacetate, and methoxytriglycol acetate;
Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, propylene acetate Acetate solvents of polyhydric alcohol partial ethers such as glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate;
Carbonate solvents such as dimethyl carbonate and diethyl carbonate;
Other carboxylic acid ester solvents include methyl acetoacetate, ethyl acetoacetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, lactic acid Examples thereof include ethyl, n-butyl lactate, n-amyl lactate, diethyl malonate, dimethyl phthalate, and diethyl phthalate.

Among these, ketone solvents and ester solvents are preferable. As the ketone solvent, a cyclic ketone solvent is more preferable, and cyclohexanone is more preferable. As the ester solvent, an acetate ester of a polyhydric alcohol partial ether is used. System solvents are more preferred, and propylene glycol monomethyl ether acetate is more preferred.
As the [F] solvent, a solvent containing 50% by mass or more of propylene glycol monomethyl ether acetate is particularly preferable because it improves the solubility of the [B] acid generator.

<[G] Uneven distribution promoter>
[G] The uneven distribution accelerator is a component that segregates the [E] polymer on the resist film surface more efficiently. When the radiation sensitive resin composition contains the [G] uneven distribution accelerator, the [E] polymer can be segregated more effectively on the resist film surface, and as a result, the amount of the [E] polymer used Can be reduced. [G] Examples of the uneven distribution accelerator include lactone compounds, carbonate compounds, nitrile compounds, polyhydric alcohols, and the like. [G] The uneven distribution promoter may be used alone or in combination of two or more.

  Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, norbornane lactone, and the like.

  Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, and the like.

  Examples of the nitrile compound include succinonitrile.

  Examples of the polyhydric alcohol include glycerin.

  Of these, lactone compounds are preferred, and γ-butyrolactone is more preferred.

  [G] The content of the uneven distribution accelerator is preferably 5 to 300 parts by mass, more preferably 10 to 100 parts by mass, and 20 to 70 parts by mass with respect to 100 parts by mass of the polymer (A). Part by mass is more preferable.

<Other optional components>
The radiation-sensitive resin composition may contain other optional components such as a surfactant, an alicyclic skeleton-containing compound, and a sensitizer in addition to the components [A] to [G]. . Other optional components may be used alone or in combination of two or more. Further, the content of other optional components can be appropriately determined according to the purpose.

(Surfactant)
Surfactants have the effect of improving coatability, striation, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. Nonionic surfactants such as stearate; commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, manufactured by Tochem Products), MegaFuck F171, F173 (above, manufactured by DIC), Florard FC430, FC431 (above, Sumitomo 3M) Manufactured by Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, manufactured by Asahi Glass Industrial Co., Ltd.) Can be mentioned. As content of surfactant in the said radiation sensitive resin composition, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

(Alicyclic skeleton-containing compound)
The alicyclic skeleton-containing compound has an effect of improving dry etching resistance, pattern shape, adhesion to the substrate, and the like.

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-Hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like. As content of the alicyclic skeleton containing compound in the said radiation sensitive resin composition, it is 5 mass parts or less normally with respect to 100 mass parts of [A] polymers.

(Sensitizer)
A sensitizer exhibits the effect | action which increases the production amount of the acid from [B] acid generator etc., and there exists an effect which improves the "apparent sensitivity" of the said radiation sensitive resin composition.

  Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like. These sensitizers may be used alone or in combination of two or more. As content of the sensitizer in the said radiation sensitive resin composition, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

<Method for preparing radiation-sensitive resin composition>
The radiation-sensitive resin composition includes, for example, [A] polymer, [B] acid generator, and [C] acid generator, [D] acid diffusion controller, [E] polymer, if necessary. F] solvent and [G] uneven distribution promoter can be prepared by mixing each arbitrary component in a predetermined ratio. As solid content concentration of the said radiation sensitive resin composition, 0.1 mass%-50 mass% are preferable, 0.5 mass%-30 mass% are more preferable, 1 mass%-10 mass% are more preferable.

<Method for forming resist pattern>
The resist pattern forming method includes a step of forming a resist film with the radiation-sensitive resin composition (hereinafter also referred to as “resist film forming step”) and a step of exposing the resist film (hereinafter referred to as “exposure step”). And a step of developing the exposed resist film (hereinafter also referred to as “development step”). Hereinafter, each step will be described.

[Resist film forming step]
In this step, a resist film is formed with the above-described radiation-sensitive resin composition of the present invention. Although it does not specifically limit as a coating method, For example, appropriate coating means, such as spin coating, cast coating, roll coating, can be employ | adopted. Examples of the substrate include a silicon wafer and a wafer coated with aluminum. Specifically, after applying the composition so that the resulting resist film has a predetermined thickness, the solvent in the coating film is volatilized by pre-baking (PB) as necessary. As a film thickness of a coating film, 10 nm-500 nm are preferable. As temperature of PB, it is 60 to 140 degreeC normally, and 80 to 120 degreeC is preferable. The PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[Exposure process]
In this step, the resist film formed in the resist film forming step is exposed. This exposure is performed by irradiating with radiation through a mask having a predetermined pattern through an immersion medium such as water in some cases. Examples of the radiation include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (wavelength 13.5 nm), X-rays, γ-rays, electron beams, α-rays, etc., depending on the line width of the target pattern. It is appropriately selected from charged particle beams and the like. Among these, when the [A] polymer of the radiation sensitive resin composition has the structural unit (I-1), far ultraviolet rays are preferable, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light, and the like. (Wavelength 248 nm) is more preferable, and ArF excimer laser light is more preferable. Moreover, when the [A] polymer of the said radiation sensitive resin composition has a structural unit (I-2) etc., an electron beam and EUV are preferable.

  Moreover, it is preferable to perform post-exposure baking (PEB) after exposure. By performing PEB, the dissociation reaction of the acid dissociable group in the exposed portion of the resist film can be smoothly advanced. As temperature of PEB, it is 50 to 180 degreeC normally, and 80 to 130 degreeC is preferable. The PEB time is usually 5 to 600 seconds, preferably 10 to 300 seconds.

  In the present invention, in order to maximize the potential of the radiation-sensitive resin composition, for example, an organic or inorganic antireflection film can be formed on the substrate to be used. Moreover, in order to prevent the influence of the basic impurity etc. which are contained in environmental atmosphere, a protective film can also be provided on a coating film, for example. Further, when performing immersion exposure, in order to avoid direct contact between the immersion medium and the resist film, for example, an immersion protective film may be provided on the resist film.

[Development process]
In this step, the resist film exposed in the exposure step is developed. Examples of the developer used for the development include an alkali developer and an organic solvent developer. Thereby, a predetermined resist pattern is formed.

  Examples of the alkali developer include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, Methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4.3.0] -5-Alkaline aqueous solution in which at least one kind of alkaline compound such as nonene is dissolved.

As the organic solvent developer, for example,
Examples of alcohol solvents include methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol and the like;
Examples of ether solvents include diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, dioxane, diphenyl ether, anisole and the like;
Examples of ketone solvents include acetone, methyl ethyl ketone, methyl-n-propyl ketone, and methyl-n-butyl ketone;
Examples of amide solvents include N, N′-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide and the like;
Examples of ester solvents include diethyl carbonate, methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, and n-butyl acetate.

  These developers may be used alone or in combination of two or more. In general, after development, the substrate is washed with water or the like and dried.

<Radiation sensitive acid generator>
The radiation sensitive acid generator of the present invention is selected from onium salt compounds having a cation represented by the above formula (1). Since the radiation sensitive acid generator has high solubility in the [F] solvent, it is possible to prevent coating unevenness when applied to the substrate surface.

<Example>
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, each measurement in an Example and a comparative example was performed with the following method.

[Weight average molecular weight (Mw) and number average molecular weight (Mn)]
Using Tosoh GPC columns (G2000HXL: 2, G3000HXL: 1, G4000HXL: 1), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1.0 mass%, sample injection amount: 100 μL Column temperature: 40 ° C., detector: measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under the analysis conditions of a differential refractometer. The degree of dispersion (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[ ¹³ C-NMR analysis]
JNM-ECX400 manufactured by JEOL Ltd. was used and deuterated chloroform was used as a measurement solvent, and an analysis for determining the content ratio (mol%) of each structural unit in each polymer was performed.

<Synthesis of compounds>
[Synthesis Example 1] (Synthesis of Compound (S-1))
In a 1000 mL round bottom flask, 43.4 g (218 mmol) of 4′-bromoacetophenone, 25.0 g (240 mmol) of 2,2-dimethyl-1,3-propanediol, 4.15 g of p-toluenesulfonic acid monohydrate ( 21.8 mmol) and 500 g of toluene were added, and the mixture was heated to reflux for 10 hours using a Dean-Stark apparatus. After cooling to room temperature, it was washed 4 times with a saturated aqueous sodium hydrogen carbonate solution and dried over anhydrous sodium sulfate. After removing the solvent, the residue was purified by column chromatography to obtain 47.8 g (yield 77%) of the acetal protected product (A).

  To a 500 mL eggplant-shaped flask, 3.16 g (130 mmol) of milled magnesium, 0.02 g of iodine, and 10 mL of dry tetrahydrofuran were added and stirred at room temperature. Thereto was slowly added dropwise a solution prepared by dissolving 28.5 g (100 mmol) of the protected acetal (A) in 60 mL of dry tetrahydrofuran to prepare a Grignard reagent. To this, 2.20 g (20.0 mmol) of dimethyl sulfite was slowly added dropwise, and then 5.43 g (50.0 mmol) of trimethylsilyl chloride was slowly added dropwise. After stirring at room temperature for 8 hours, 10 mL of 3M hydrochloric acid was added. After adding 40 mL of dichloromethane, washing with water was performed 4 times and dried over anhydrous sodium sulfate. After distilling off the solvent, the residue was purified by column chromatography to obtain 9.5 g of chloride (B) (yield 69%).

To a 300 mL eggplant-shaped flask, 6.86 g (10.0 mmol) of chloride (B), 4.56 g (11.0 mmol) of sulfonic acid sodium salt (C), 100 mL of dichloromethane, and 50 mL of water were added and stirred at room temperature for 12 hours. The organic phase was washed with water four times and then dried over anhydrous sodium sulfate. After the solvent was distilled off, purification by column chromatography yielded (S-1) in 8.78 g (yield 84%).

[Synthesis Example 2 to Synthesis Example 6] (Synthesis of Compounds (S-2) to (S-6))
A precursor represented by the following formulas (S-2) to (S-6) was synthesized by appropriately selecting a precursor of the acetal protector and performing the same operation as in Example 1.

<Synthesis of [A] polymer and [E] polymer>
Monomers [compound (M-1) to compound (M-5)] used in the synthesis of each polymer in each example and comparative example are shown below.

[Synthesis Example 7] (Synthesis of Polymer (A-1))
Compound (M-1) 7.97 g (35 mol%), compound (M-2) 7.44 g (45 mol%), and compound (M-3) 4.49 g (20 mol%) were converted to 2-butanone 40 g. The monomer solution was prepared by adding 0.80 g of AIBN (5 mol% based on the total monomers) as an initiator. Next, a 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. The polymerization solution cooled in 400 g of methanol was added, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 80 g of methanol, filtered, and dried at 50 ° C. for 17 hours to synthesize a white powder polymer (A-1) (15.2 g, yield 76). %). Mw of the polymer (A-1) was 7,300, and Mw / Mn was 1.53. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from the compound (M-1), the compound (M-2), and the compound (M-3) is 34.3 mol% and 45.1 mol, respectively. %, And 20.6 mol%.

[Synthesis Example 8] (Synthesis of polymer (E-1))
Compound (M-4) 79.9 g (70 mol%) and compound (M-5) 20.91 g (30 mol%) were dissolved in 100 g of 2-butanone, and dimethyl 2,2′-azo was used as an initiator. A monomer solution was prepared by dissolving 4.77 g of bisisobutyrate. Next, a 1,000 mL three-necked flask containing 100 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the monomer solution prepared above was added dropwise over 3 hours using a dropping funnel. . The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. The reaction solution was transferred to a 2 L separatory funnel, and then the polymerization solution was uniformly diluted with 150 g of n-hexane, and 600 g of methanol was added and mixed.
Next, 30 g of distilled water was added, and the mixture was further stirred and allowed to stand for 30 minutes. Thereafter, the lower layer was recovered to obtain a propylene glycol monomethyl ether acetate solution containing the polymer (E-1) as a solid content (yield 60%). Mw of the polymer (E-1) was 7,200, and Mw / Mn was 2.00. As a result of ¹³ C-NMR analysis, the content of each structural unit derived from the compound (M-4) and the compound (M-5) was 71.1 mol% and 28.9 mol%, respectively.

<Preparation of photoresist composition (I)>
The [B] acid generator, [C] acid diffusion controller, [F] solvent and [G] uneven distribution accelerator used in the preparation of the photoresist compositions (I) of the following Examples and Comparative Examples are shown below. .

[B] Acid generator

[C] Acid diffusion controller

[F] Solvent F-1: Propylene glycol monomethyl ether acetate F-2: Cyclohexanone

[G] Uneven distribution promoter G-1: γ-butyrolactone

[Examples 1 to 6 and Comparative Example 1]
<Solubility test in propylene glycol acetate monomethyl ether>
1.00 g of the target compound was weighed into a sample bottle, and propylene glycol monomethyl ether acetate was added thereto to make the total mass 10.0 g. After attaching a lid to the sample bottle, table-top ball mill stirring was performed at room temperature (25 ° C.) for 1 hour. When the sample immediately after stirring was visually observed, the case where turbidity or precipitation was confirmed was indicated as “x”. Although it was not confirmed immediately after stirring, an increase in turbidity or precipitation was confirmed after storage at 5 ° C. for 2 weeks. The product was indicated as “Δ”, and the product in which no turbidity or precipitation was confirmed even after storage at 5 ° C. for 1 month or more immediately after stirring was indicated as “◯”. The results are shown in Table 1.

  As shown in Table 1, the acid generators of Examples 1 to 6 had good solubility in PGMEA, but in the compound of Comparative Example 1 (B-1), turbidity and precipitation were confirmed immediately after stirring, In the compound (B-2) of Comparative Example 2, turbidity and increase in precipitation were confirmed with the passage of time.

[Example 7]
[A] 100 parts by mass of (A-1) as the polymer, 8.5 parts by mass of (S-1) as the [B] acid generator, and 2 (C-1) as the [C] acid diffusion controller. .3 parts by weight, 3 parts by weight of (E-1) as the [E] polymer, 3,200 parts by weight of (F-1) as the [F] solvent, and (H- 30 parts by mass of 1) was blended to prepare a photoresist composition (J-1).

[Examples 8 to 12]
Photoresist compositions (J-2) to (J-6) were prepared in the same manner as in Example 1 except that the components of the types and amounts shown in Table 2 were used.

[Comparative Example 2]
[C] Except that the acid generator was changed to (C-1), the same operation as in Example 1 was carried out to prepare a photoresist composition. As a result, the solution became cloudy and could not be prepared.
[Comparative Examples 3 to 4]
[C] Implemented except that the acid generator was (C-1) or (B-2) and the [F] solvent was (F-1) 2,240 parts by mass and (F-2) 960 parts by mass. In the same manner as in Example 1, photoresist compositions (J-7) to (J-8) were prepared.

<Formation of resist pattern (1)>
Using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron) on the surface of a 12-inch silicon wafer, a composition for forming an antireflection film (ARC66, manufactured by Brewer Science) was applied, and then heated at 205 ° C. for 60 seconds. As a result, a lower antireflection film having a thickness of 105 nm was formed. On the lower antireflection film, each of the prepared photoresist compositions was applied using the spin coater, and PB was performed at 90 ° C. for 60 seconds. Then, it cooled at 23 degreeC for 30 second, and formed the resist film with a film thickness of 90 nm. Next, this resist film is 40 nm under an optical condition of NA = 1.3 and dipole (Sigma 0.977 / 0.782) using an ArF excimer laser immersion exposure apparatus (NSR-S610C, manufactured by NIKON). Exposure was through a line and space (1L1S) mask pattern. After the exposure, PEB was performed at 90 ° C. for 60 seconds. Thereafter, alkali development was performed using a 2.38% by mass TMAH aqueous solution as an alkali developer, washed with water, and dried to form a positive resist pattern. When this resist pattern is formed, the line width formed through a one-to-one line and space mask having a target dimension of 40 nm is defined as an optimum exposure amount. did.

<Formation of resist pattern (2)>
A negative resist pattern was prepared in the same manner as in the above resist pattern formation (1) except that n-butyl acetate was used instead of the TMAH aqueous solution and the organic solvent was developed, and washing with water was not performed. Formed.

<Evaluation>
About the resist pattern formed also using each said photoresist composition, LWR performance, resolution, cross-sectional shape, and depth of focus were evaluated in accordance with the following method. The results are shown in Table 3. For measuring the resist pattern, a scanning electron microscope (S-9380, manufactured by Hitachi High-Technologies Corporation) was used.

[LWR performance]
The resist pattern was observed from above the pattern using the scanning electron microscope. A total of 50 line widths were measured at arbitrary points, and a 3-sigma value was obtained from the distribution of the measured values, and this was defined as LWR performance. The LWR performance indicates that the smaller the value, the better. When compared with the comparative example, the equivalent or better LWR performance was “◯”, and the equivalent or lower LWR performance was “x”.

[Resolution]
The dimension of the minimum resist pattern that can be resolved at the optimum exposure dose was measured, and the measurement result was defined as resolution. The smaller the measured value, the better the resolution. When the measured values obtained were compared with those of Comparative Examples 3 and 4, a resolution equal to or higher than that of each was “◯”, and a resolution equal to or lower than that was “×”.

  As shown in Table 3, in the case of ArF exposure, the radiation sensitive resin compositions of Examples 7 to 12 have LWR performance, both in the case of a positive type by alkali development and in the case of a negative type by organic solvent development. Both resolutions were excellent. On the other hand, the composition of Comparative Example 3 containing the compound of B-1 as an acid generator was inferior in LWR performance and resolution as compared with Examples 7-12.

  According to the radiation sensitive resin composition and the resist pattern forming method of the present invention, a resist pattern having a small LWR and a high resolution can be formed. The acid generator of the present invention is excellent in solubility in a solvent, and can be suitably used as a component of the radiation sensitive resin composition.

Claims (7)

A polymer having a structural unit containing an acid dissociable group;
A radiation-sensitive resin composition comprising one or more radiation-sensitive acid generators selected from onium salt compounds having a cation represented by the following formula (1).

[In Formula (1), X is a sulfur atom or an iodine atom, Y is a (1 + a) -valent aromatic ring-containing group, and A and B are each independently an oxygen atom, a sulfur atom, or a nitrogen atom. R ¹ and R ² are each independently a monovalent organic group, R ³ is a hydrogen atom or a monovalent organic group, R ⁴ is a single bond, R ¹ , R ² , R ³ and R ⁴ may be linked to each other to form a ring together with A, B or carbon atoms to which each two are bonded. R ⁵ is a monovalent organic group, and when a plurality of R ⁵ are present, they may be linked together to form a ring with X. a is an integer of 1 to 5, b is an integer of 1 to 3, and c is an integer of 0 to 2. However, when X is a sulfur atom, b + c = 3, and when X is an iodine atom, b + c = 2. ]   2. The radiation-sensitive resin composition according to claim 1, wherein A and B in the formula (1) are oxygen atoms in the onium salt compound having a cation represented by the formula (1). The onium salt compound having a cation represented by the formula (1) is a cation represented by the following formula (1-1), a cation represented by the following formula (1-2), and the following formula (1-3). The radiation sensitive resin composition according to claim 1 or 2, which is an onium salt compound having at least one cation selected from cations represented by formula (1).

[In the formulas (1-1) to (1-3), R ¹ and R ² are each independently a monovalent organic group, which are connected to each other to form a ring together with the oxygen atoms to which they are bonded. It may be. R ³¹ is an alkyl group having 1 to 6 carbon atoms, and each R is independently an alkyl group, an alkoxy group, a hydroxy group, or a halogen atom. b1 is an integer of 1 to 3, and c1 is an integer of 0 to 2. However, b1 + c1 = 3. b2 is 1 or 2, and c2 is 0 or 1. However, b2 + c2 = 2. d1, d2 and h are each independently an integer of 0 to 4, e1 and e2 are each independently an integer of 0 to 5, and f is an integer of 0 to 6. ]   The radiation-sensitive resin composition according to any one of claims 1 to 3, further comprising a solvent containing 50 mass% or more of propylene glycol monomethyl ether (PGMEA). Forming a resist film using the radiation-sensitive resin composition according to any one of claims 1 to 4,
A resist pattern forming method comprising: exposing the resist film; and developing the exposed resist film. The radiation sensitive acid generator chosen from the onium salt compound which has a cation represented by following formula (1).

[In Formula (1), X is a sulfur atom or an iodine atom, Y is a (1 + a) -valent aromatic ring-containing group, and A and B are each independently an oxygen atom, a sulfur atom, or a nitrogen atom. R ¹ and R ² are each independently a monovalent organic group, R ³ is a hydrogen atom or a monovalent organic group, R ⁴ is a single bond, R ¹ , R ² , R ³ and Any two of R ⁴ may be connected to each other to form a ring together with A, B, or carbon atoms to which they are bonded. R ⁵ is a monovalent organic group, and when a plurality of R ⁵ are present, they may be linked together to form a ring with X. a is an integer of 1 to 5, b is an integer of 1 to 3, and c is an integer of 0 to 2. However, when X is a sulfur atom, b + c = 3, and when X is an iodine atom, b + c = 2. ] The onium salt compound having a cation represented by the formula (1) is a cation represented by the following formula (1-1), a cation represented by the following formula (1-2), and the following formula (1-3). The radiation-sensitive acid generator according to claim 6, which is an onium salt compound having at least one cation selected from cations represented by:

[In the formulas (1-1) to (1-3), R ¹ and R ² are each independently a monovalent organic group, which are connected to each other to form a ring together with the oxygen atoms to which they are bonded. It may be. R ³¹ is an alkyl group having 1 to 6 carbon atoms, and each R is independently an alkyl group, an alkoxy group, a hydroxy group, or a halogen atom. b1 is an integer of 1 to 3, and c1 is an integer of 0 to 2. However, b1 + c1 = 3. b2 is 1 or 2, and c2 is 0 or 1. However, b2 + c2 = 2. d1, d2 and h are each independently an integer of 0 to 4, e1 and e2 are each independently an integer of 0 to 5, and f is an integer of 0 to 6. ]