WO2024101390A1

WO2024101390A1 - Resist composition, resist pattern formation method, and compound

Info

Publication number: WO2024101390A1
Application number: PCT/JP2023/040221
Authority: WO
Inventors: 諒大小林; 広樹加藤
Original assignee: 東京応化工業株式会社
Priority date: 2022-11-10
Filing date: 2023-11-08
Publication date: 2024-05-16
Also published as: JP2024070085A

Abstract

A resist composition containing a resin component (A1) having a structural unit (a0) derived from a compound represented by general formula (a0-1) (In the formula, R is a hydrogen atom, a C1-5 alkyl group, or a C1-5 halogenated alkyl group; La01 and La02 are each independently a single bond or a divalent linking group; Ar is an aromatic ring; Ra01 is a substituent other than a hydroxy group; m1 is an integer greater than or equal to 0, provided that valence requirements are met; and Rpg is an acid-dissociable group represented by general formula (a0-pg).)

Description

Resist composition, method for forming resist pattern, and compound

The present invention relates to a resist composition, a method of forming a resist pattern, and a compound.
This application claims priority based on Japanese Patent Application No. 2022-180462, filed in Japan on November 10, 2022, the contents of which are incorporated herein by reference.

In recent years, advances in lithography technology have led to rapid progress in miniaturizing patterns in the manufacture of semiconductor elements and liquid crystal display elements. A common method of miniaturization is to shorten the wavelength (increase the energy) of the exposure light source.

Resist materials are required to have lithography properties such as sensitivity to these exposure light sources and resolution capable of reproducing patterns with fine dimensions.
As a resist material that satisfies such requirements, a chemically amplified resist composition that contains a base component whose solubility in a developer changes due to the action of acid, and an acid generator component that generates acid upon exposure, has been used so far.

For example, Patent Document 1 discloses a resist composition that contains a resin component having a styrene carboxylic acid skeleton and a structural unit in which an acid-dissociable group is bonded to the end of the side chain. It is disclosed that this resist composition can achieve high sensitivity and improve lithography properties such as resolution and LWR.

JP 2019-219469 A

As lithography technology continues to advance and its application fields expand, patterns are becoming increasingly fine. As a result, there is a demand for technology that can form fine patterns with good shapes when manufacturing semiconductor devices, etc. For example, the goal of EUV and EB lithography is to form fine patterns of several tens of nanometers.

The present invention has been made in consideration of the above circumstances, and aims to provide a resist composition that provides high sensitivity and good resolution when forming a resist pattern, a method for forming a resist pattern using said resist composition, and a compound that is useful as a raw material for the base component used in said resist composition.

In order to solve the above problems, the present invention employs the following configuration.
That is, a first aspect of the present invention is a resist composition that generates acid upon exposure, and whose solubility in a developer changes due to the action of the acid, the resist composition containing a resin component (A1) whose solubility in a developer changes due to the action of an acid, the resin component (A1) having a structural unit (a0) derived from a compound represented by the following general formula (a0-1):

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; La ⁰¹ and La ⁰² are each independently a single bond or a divalent linking group; Ar is an aromatic ring; Ra ⁰¹ is a substituent other than a hydroxy group; m1 is an integer of 0 or more as long as the valence allows; and Rpg is an acid-dissociable group represented by the following general formula (a0-pg).]

[In the formula, * is a bond bonded to -O- in -La ⁰² -C(═O)-O-; Ra ⁰² is a hydrogen atom or a hydrocarbon group; C ¹ is a secondary carbon atom or a tertiary carbon atom; A is an aliphatic ring having 6 or more carbon atoms; C ² and C ³ are each independently a carbon atom constituting a carbon-carbon unsaturated bond forming a part of the ring skeleton of the aliphatic ring having 6 or more carbon atoms in A; Ra ⁰³ and Ra ⁰⁴ are each independently a hydrogen atom or a hydrocarbon group; Ra ⁰⁵ is a hydrocarbon group; n1 is an integer of 0 or more as far as the valence allows; with the proviso that C ¹ does not constitute a part of a crosslinked structure; and when Ra ⁰² , Ra ⁰³ and Ra ⁰⁴ are all hydrogen atoms, n1 is an integer of 1 or more.]

The second aspect of the present invention is a method for forming a resist pattern, comprising the steps of forming a resist film on a support using the resist composition according to the first aspect, exposing the resist film to light, and developing the exposed resist film to form a resist pattern.

The third aspect of the present invention is a compound represented by the following general formula (a0-1):

The present invention provides a resist composition that provides high sensitivity and good resolution when forming a resist pattern, a method for forming a resist pattern using the resist composition, and a compound that is useful as a raw material for the base component used in the resist composition.

In this specification and claims, the term "aliphatic" is a relative concept to aromaticity and is defined as meaning a group, compound, etc. that does not have aromaticity.
Unless otherwise specified, the term "alkyl group" includes linear, branched and cyclic monovalent saturated hydrocarbon groups. The same applies to the alkyl group in an alkoxy group.
Unless otherwise specified, the term "alkylene group" includes linear, branched and cyclic divalent saturated hydrocarbon groups.
The "halogen atom" includes a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
The term "structural unit" refers to a monomer unit that constitutes a polymeric compound (resin, polymer, copolymer).
The phrase "may have a substituent" includes both the case where a hydrogen atom (--H) is replaced with a monovalent group and the case where a methylene group (--CH ₂ -) is replaced with a divalent group.
The term "exposure" is intended to include any concept including irradiation with radiation.

The term "acid-decomposable group" refers to a group having acid decomposability in which at least a part of the bonds in the structure of the acid-decomposable group can be cleaved by the action of an acid.
Examples of acid-decomposable groups whose polarity increases under the action of an acid include groups that are decomposed by the action of an acid to generate a polar group.
Examples of the polar group include a carboxy group, a hydroxyl group, an amino group, and a sulfo group (-SO ₃ H).
More specific examples of the acid-decomposable group include groups in which the polar group is protected with an acid-dissociable group (for example, a group in which the hydrogen atom of an OH-containing polar group is protected with an acid-dissociable group).

The term "acid dissociable group" refers to both (i) a group having acid dissociability in which the bond between the acid dissociable group and an atom adjacent to the acid dissociable group can be cleaved by the action of an acid, and (ii) a group in which a part of the bond is cleaved by the action of an acid and then a decarboxylation reaction occurs, thereby cleaving the bond between the acid dissociable group and an atom adjacent to the acid dissociable group.
The acid dissociable group constituting the acid decomposable group must be a group with lower polarity than the polar group generated by dissociation of the acid dissociable group, and thus, when the acid dissociable group is dissociated by the action of acid, a polar group with higher polarity than the acid dissociable group is generated, and the polarity increases.As a result, the polarity of the entire (A1) component increases.By increasing the polarity, the solubility in the developer changes relatively, and when the developer is an alkaline developer, the solubility increases, and when the developer is an organic developer, the solubility decreases.

The "base material component" is an organic compound that has film-forming ability. Organic compounds used as base material components are broadly divided into non-polymers and polymers. Non-polymers usually have a molecular weight of 500 or more and less than 4000 (hereinafter referred to as "low molecular weight compounds"). Hereinafter, "resin," "polymeric compound," or "polymer" refers to a polymer with a molecular weight of 1000 or more. The molecular weight of the polymer is determined by the weight average molecular weight calculated in terms of polystyrene by GPC (gel permeation chromatography).

The term "derived structural unit" refers to a structural unit formed by cleavage of a multiple bond between carbon atoms, for example, an ethylenic double bond.
In the "acrylic acid ester", the hydrogen atom bonded to the carbon atom at the α-position may be substituted with a substituent. The substituent (R ^αx ) substituting the hydrogen atom bonded to the carbon atom at the α-position is an atom or group other than a hydrogen atom. It also includes an itaconic acid diester in which the substituent (R ^αx ) is substituted with a substituent containing an ester bond, and an α-hydroxyacrylic ester in which the substituent (R ^αx ) is substituted with a hydroxyalkyl group or a group in which the hydroxyl group is modified. The carbon atom at the α-position of an acrylic acid ester refers to the carbon atom to which the carbonyl group of acrylic acid is bonded, unless otherwise specified.
Hereinafter, an acrylic ester in which the hydrogen atom bonded to the carbon atom at the α-position is substituted with a substituent will sometimes be referred to as an α-substituted acrylic ester.

The term "derivative" refers to a concept that includes compounds in which the hydrogen atom at the α-position of the target compound is replaced with other substituents such as an alkyl group or a halogenated alkyl group, as well as derivatives thereof. Examples of such derivatives include compounds in which the hydrogen atom of the hydroxyl group of a target compound, which may have the hydrogen atom at the α-position replaced with a substituent, is replaced with an organic group; compounds in which the hydrogen atom at the α-position of the target compound, which may have the hydrogen atom at the α-position replaced with a substituent, is bonded to a substituent other than a hydroxyl group, and the like. The α-position refers to the first carbon atom adjacent to the functional group, unless otherwise specified.
Examples of the substituent that substitutes the hydrogen atom at the α-position of the hydroxystyrene include the same as those for R ^αx .

In this specification and claims, some structures represented by chemical formulas may have asymmetric carbons, and enantiomers or diastereoisomers may exist. In such cases, a single chemical formula is used to represent all of the isomers. These isomers may be used alone or as a mixture.

(Resist Composition)
The resist composition of this embodiment generates an acid upon exposure, and the solubility of the resist composition in a developer changes due to the action of the acid.
The resist composition contains a base component (A) (hereinafter also referred to as "component (A)") whose solubility in a developer changes under the action of an acid. The component (A1) has a structural unit (a0) derived from a compound represented by general formula (a0) described below.
Furthermore, the resist composition of this embodiment may further contain other components in addition to the component (A). Examples of other components include the below-described component (B), component (D), component (E), component (F), and component (S).

In the resist composition of this embodiment, the component (A) may generate an acid upon exposure, or an additive component that is formulated separately from the component (A) may generate an acid upon exposure.
Specifically, the resist composition of this embodiment may be one that further contains (1) an acid generator component (B) that generates an acid upon exposure (hereinafter referred to as “component (B)”); (2) the component (A) may be a component that generates an acid upon exposure; or (3) the component (A) is a component that generates an acid upon exposure, and further contains component (B).
That is, in the above cases of (2) and (3), the component (A) is a "base component that generates an acid upon exposure and changes its solubility in a developer by the action of the acid". When the component (A) is a base component that generates an acid upon exposure and changes its solubility in a developer by the action of the acid, the component (A1) described below is preferably a resin that generates an acid upon exposure and changes its solubility in a developer by the action of the acid. As such a resin, a polymer compound having a structural unit that generates an acid upon exposure can be used. As the structural unit that generates an acid upon exposure, a known one can be used.

The resist composition of this embodiment is preferably the above-mentioned case (1). In other words, the resist composition of this embodiment preferably contains component (A) and component (B).

When a resist film is formed using the resist composition of this embodiment and selective exposure is performed on the resist film, for example, an acid is generated from component (B) in the exposed parts of the resist film, and the action of the acid changes the solubility of component (A) in the developer, whereas the solubility of component (A) in the developer does not change in the unexposed parts of the resist film, resulting in a difference in solubility in the developer between the exposed and unexposed parts. Therefore, when the resist film is developed, if the resist composition is a positive type, the exposed parts of the resist film are dissolved and removed to form a positive type resist pattern, and if the resist composition is a negative type, the unexposed parts of the resist film are dissolved and removed to form a negative type resist pattern.

The resist composition of this embodiment may be a positive resist composition or a negative resist composition. The resist composition of this embodiment may be for an alkaline development process in which an alkaline developer is used in the development treatment during resist pattern formation, or may be for a solvent development process in which a developer containing an organic solvent (organic developer) is used in the development treatment.

<Component (A)>
In the resist composition of this embodiment, the component (A) contains a resin component (A1) (hereinafter also referred to as “component (A1)”) whose solubility in a developer changes under the action of an acid.
By using the component (A1), the polarity of the base component changes between before and after exposure, making it possible to obtain good development contrast not only in an alkali development process but also in a solvent development process.
As the component (A), other polymeric compounds and/or low molecular weight compounds may be used in combination with the component (A1).
The component (A) may be a "base component that generates an acid upon exposure and changes its solubility in a developer by the action of the acid". When the component (A) is a base component that generates an acid upon exposure and changes its solubility in a developer by the action of the acid, the component (A1) is preferably a resin that generates an acid upon exposure and changes its solubility in a developer by the action of the acid. As such a resin, a polymer compound having a structural unit that generates an acid upon exposure can be used. As the structural unit that generates an acid upon exposure, a known one can be used.

In the resist composition of this embodiment, the component (A) may be used alone or in combination of two or more types.

Regarding the Component (A1) The component (A1) is a resin component whose solubility in a developer changes due to the action of an acid.
The component (A1) has a structural unit (a0) derived from a compound represented by general formula (a0-1) shown below.
The component (A1) may contain other structural units, in addition to the structural unit (a0), as necessary.

In the formula (a0-1), R is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms, and from the viewpoint of industrial availability, a hydrogen atom, a methyl group, or a trifluoromethyl group is more preferable, a hydrogen atom or a methyl group is even more preferable, and a hydrogen atom is particularly preferable.

In the formula (a0-1), the divalent linking group in La ⁰¹ and La ⁰² is not particularly limited, but suitable examples thereof include a divalent hydrocarbon group which may have a substituent, and a divalent linking group containing a hetero atom.

La ⁰¹ is preferably a single bond, an ester bond [-C(=O)-O-, -O-C(=O)-], an ether bond (-O-), a linear or branched alkylene group, or a combination thereof, and more preferably a single bond or an ester bond [-C(=O)-O-, -O-C(=O)-]. Of these, from the viewpoint of increasing sensitivity and improving resolution, a single bond is particularly preferable as La ⁰¹ .

La ⁰² is preferably a single bond, an ester bond [-C(=O)-O-, -O-C(=O)-], an ether bond (-O-), a linear or branched alkylene group, or a combination thereof, and more preferably a single bond, -C(=O)-O-La ⁰²¹ -, -O-C(=O)-La ⁰²¹ -]. La ⁰²¹ is an alkylene group having 1 to 5 carbon atoms. Among these, from the viewpoint of increasing sensitivity and improving resolution, a single bond is particularly preferable as La ⁰² .

In the formula (a0-1), the aromatic ring in Ar is not particularly limited as long as it is a cyclic conjugated system having 4n+2 π electrons, and may be a monocyclic or polycyclic ring. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, further preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms.
Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene.
Among these, Ar is preferably a benzene ring, a naphthalene ring or an anthracene ring, more preferably a benzene ring or a naphthalene ring, and even more preferably a benzene ring.

In the formula (a0-1), examples of the substituent in Ra ⁰¹ include an alkyl group having 1 to 5 carbon atoms, a carboxyl group, a halogen atom, a halogenated alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an alkyloxycarbonyl group having 1 to 5 carbon atoms. The substituent in Ra ⁰¹ is preferably an alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group.

In the formula (a0-1), m1 is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

In the above formula (a0-pg), the hydrocarbon group for Ra ⁰² may be linear or branched, and may be saturated or unsaturated.
Examples of the saturated hydrocarbon group for Ra ⁰² include a linear alkyl group having 1 to 12 carbon atoms and a branched alkyl group having 1 to 12 carbon atoms.
Examples of the unsaturated hydrocarbon group for Ra ⁰² include linear alkenyl groups having 2 to 12 carbon atoms, branched alkenyl groups having 2 to 12 carbon atoms, and linear or branched alkynyl groups having 2 to 12 carbon atoms.

Examples of the linear alkyl group having 1 to 12 carbon atoms for Ra ⁰² include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, and the like. A linear alkyl group having 1 to 5 carbon atoms is preferable, a methyl group, an ethyl group, or a butyl group is more preferable, and a methyl group or an ethyl group is even more preferable.

Examples of the branched alkyl group having 1 to 12 carbon atoms for Ra ⁰² include an isopropyl group, an isobutyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a 1,1-diethylpropyl group, and a 2,2-dimethylbutyl group. A branched alkyl group having 3 to 5 carbon atoms is preferable, and an isopropyl group is more preferable.

Examples of the unsaturated hydrocarbon group for Ra ⁰² include -CH=CH ₂ , -CH=CHCH ₃ , -CH ₂ -CH=CH ₂ , -CH ₂ -CH=CHCH ₃ , -CH ₂ -(CH ₃ )C=CH ₂ , -CH ₂ CH ₂ -CH=CH ₂ , -CH ₂ CH ₂ -(CH ₃ )C=CH ₂ , -C≡CH, -C≡CCH ₃ , -CH ₂ -C≡CH, -CH ₂ -C≡CCH ₃ and the like.

In the above formula (a0-pg), Ra ⁰² is preferably a hydrogen atom or a saturated hydrocarbon group.

In the above formula (a0-pg), when Ra ⁰² is a hydrogen atom, C ¹ is a secondary carbon atom, and when Ra ⁰² is an alkyl group, C ¹ is a tertiary carbon atom.

In the above formula (a0-pg), the aliphatic ring for A may be a polycyclic group or a monocyclic group.
The aliphatic ring that is a monocyclic group is preferably a group in which one hydrogen atom has been removed from a monocycloalkene. The monocycloalkene preferably has 6 to 10 carbon atoms, and specific examples thereof include cyclohexene, cycloheptene, cyclooctene, cyclononene, and cyclodecene.
The cyclic alkene which is a polycyclic group is preferably a group in which one hydrogen atom has been removed from a polycycloalkene, and the polycycloalkene preferably has 7 to 12 carbon atoms. Specific examples thereof include bicyclo[3.1.1]hept-2-ene, tricyclodecene, and tetracyclododecene.
Among these, the aliphatic ring having 6 or more carbon atoms for A is more preferably a group in which one hydrogen atom has been removed from a monocycloalkene or a polycycloalkene, even more preferably a group in which one hydrogen atom has been removed from cyclohexene, cycloheptene, or bicyclo[3.1.1]hept-2-ene, and particularly preferably a group in which one hydrogen atom has been removed from cyclohexene.

In the above formula (a0-pg), examples of the saturated hydrocarbon group for Ra ⁰³ and Ra ⁰⁴ include a linear or branched alkyl group.
The linear alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and most preferably 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group.
The branched alkyl group preferably has 3 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and most preferably 3 to 10 carbon atoms. Specific examples include an isopropyl group, an isobutyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a 1,1-diethylpropyl group, and a 2,2-dimethylbutyl group.

Examples of the unsaturated hydrocarbon group for Ra ⁰³ and Ra ⁰⁴ include -CH=CH ₂ , -CH=CHCH ₃ , -CH ₂ -CH=CH ₂ , -CH ₂ -CH=CHCH ₃ , -CH ₂ -(CH ₃ )C=CH ₂ , -CH ₂ CH ₂ -CH=CH ₂ , -CH ₂ CH ₂ -(CH ₃ )C=CH ₂ , -C≡CH, -C≡CCH ₃ , -CH ₂ -C≡CH, -CH ₂ -C≡CCH ₃ and the like.

Among these, it is preferable that one of Ra ⁰³ and Ra ⁰⁴ is a hydrogen atom and the other is a chain alkyl group having 1 to 20 carbon atoms, it is more preferable that one of Ra ⁰³ and Ra ⁰⁴ is a hydrogen atom and the other is a chain alkyl group having 1 to 10 carbon atoms, and it is even more preferable that one of Ra ⁰³ and Ra ⁰⁴ is a hydrogen atom and the other is a chain alkyl group having 1 to 5 carbon atoms.

In the above formula (a0-pg), the hydrocarbon group for Ra ⁰⁵ may be linear or branched, and may be saturated or unsaturated.
Examples of the saturated hydrocarbon group for Ra ⁰⁵ include a linear alkyl group having 1 to 12 carbon atoms and a branched alkyl group having 1 to 12 carbon atoms.
Examples of the unsaturated hydrocarbon group for Ra ⁰⁵ include linear alkenyl groups having 2 to 12 carbon atoms, branched alkenyl groups having 2 to 12 carbon atoms, and linear or branched alkynyl groups having 2 to 12 carbon atoms.

Examples of the linear alkyl group having 1 to 12 carbon atoms for Ra ⁰⁵ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, and the like. A linear alkyl group having 1 to 5 carbon atoms is preferable, a methyl group, an ethyl group, or a butyl group is more preferable, and a methyl group or an ethyl group is even more preferable.

Examples of the branched alkyl group having 1 to 12 carbon atoms for Ra ⁰⁵ include an isopropyl group, an isobutyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a 1,1-diethylpropyl group, and a 2,2-dimethylbutyl group. A branched alkyl group having 3 to 5 carbon atoms is preferable, and an isopropyl group is more preferable.

Examples of the unsaturated hydrocarbon group for Ra ⁰⁵ include -CH=CH ₂ , -CH=CHCH ₃ , -CH ₂ -CH=CH ₂ , -CH ₂ -CH=CHCH ₃ , -CH ₂ -(CH ₃ )C=CH ₂ , -CH ₂ CH ₂ -CH=CH ₂ , -CH ₂ CH ₂ -(CH ₃ )C=CH ₂ , -C≡CH, -C≡CCH ₃ , -CH ₂ -C≡CH, -CH ₂ -C≡CCH ₃ and the like.

In the above formula (a0-pg), Ra ⁰⁵ is preferably an alkyl group, more preferably an alkyl group having 1 to 5 carbon atoms, still more preferably an alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl group.

In the formula (a0-pg), n1 is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

In formula (a0-pg), ^C1 does not constitute a part of a crosslinked structure. In addition, in formula (a0-pg), when ^Ra02 , ^Ra03 and ^Ra04 are all hydrogen atoms, n1 is an integer of 1 or more. In other words, the aliphatic ring having 6 or more carbon atoms in A has at least one alkyl group as a substituent.

The structural unit (a0) may be a structural unit derived from a compound represented by the following general formula (a0-s1):

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; La ⁰¹ and La ⁰² are each independently a single bond or a divalent linking group; Ar is an aromatic ring; Ra ⁰¹ is a substituent other than a hydroxy group; m1 is an integer of 0 or more as long as the valence allows; Cs is a secondary carbon atom; A is an aliphatic ring having 6 or more carbon atoms; C ² and C ³ are each independently a carbon atom constituting a carbon-carbon unsaturated bond that forms part of the ring skeleton of the aliphatic ring having 6 or more carbon atoms in A; Ra ⁰³¹ and Ra ⁰⁴¹ are each independently a hydrogen atom or a hydrocarbon group; Ra ⁰⁵¹ is a hydrocarbon group; n11 is an integer of 0 or more as long as the valence allows; provided that when Ra ⁰³¹ and Ra ⁰⁴¹ are both hydrogen atoms, n11 is an integer of 1 or more.]

In the formula (a0-s1), R, La ⁰¹ , La ⁰² , Ar, Ra ⁰¹ and m1 are the same as R, La ⁰¹ , La ⁰² , Ar, Ra ⁰¹ and m1 in the formula (a0-1), respectively.
In the formula (a0-s1), A, ^C2 and ^C3 are the same as A, ^C2 and ^C3 in the formula (a0-pg), respectively.
In the formula (a0-s1), Ra ⁰³¹ , Ra ⁰⁴¹ , Ra ⁰⁵¹ and n11 are the same as Ra ⁰³ , Ra ⁰⁴ , Ra ⁰⁵ and n1 in the formula (a0-pg), respectively.

The structural unit (a0) may be a structural unit derived from a compound represented by the following general formula (a0-t1):

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; La ⁰¹ and La ⁰² are each independently a single bond or a divalent linking group; Ar is an aromatic ring; Ra ⁰¹ is a substituent other than a hydroxyl group; m1 is an integer of 0 or more as long as the valence allows; Ra ⁰²² is a hydrocarbon group; Ct is a tertiary carbon atom; A is an aliphatic ring having 6 or more carbon atoms; C ² and C ³ are each independently a carbon atom constituting a carbon-carbon unsaturated bond that forms part of the ring skeleton of the aliphatic ring having 6 or more carbon atoms in A; Ra ⁰³² and Ra ⁰⁴² are each independently a hydrogen atom or a hydrocarbon group; Ra ⁰⁵² is a hydrocarbon group; n12 is an integer of 0 or more as long as the valence allows.]

In the formula (a0-t1), R, La ⁰¹ , La ⁰² , Ar, Ra ⁰¹ and m1 are the same as R, La ⁰¹ , La ⁰² , Ar, Ra ⁰¹ and m1 in the formula (a0-1), respectively.
In the formula (a0-t1), A, ^C2 and ^C3 are the same as A, ^C2 and ^C3 in the formula (a0-pg), respectively.
In the formula (a0-t1), Ra ⁰²² , Ra ⁰³² , Ra ⁰⁴² , Ra ⁰⁵² and n12 are the same as Ra ⁰² , Ra ⁰³ , Ra ⁰⁴ , Ra ⁰⁵ and n1 in the formula (a0-pg), respectively.

Specific examples of the structural unit (a0) are shown below: In each of the following formulas, R ^α represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

The structural unit (a0) contained in the component (A1) may be of one type, or may be of two or more types.
The proportion of the structural unit (a0) in the component (A1) is preferably 40 to 80 mol %, more preferably 45 to 75 mol %, even more preferably 50 to 70 mol %, and particularly preferably 55 to 65 mol %, based on the total (100 mol %) of all structural units constituting the component (A1).
When the content of the structural unit (a0) is at least as large as the lower limit of the above preferred range, sensitivity is likely to be increased, whereas when the content is at most the upper limit, a good balance with other structural units is easily achieved, and resolution is likely to be improved.

Other structural units
The component (A1) may contain other structural units, in addition to the structural unit (a0) described above, as necessary.
Examples of other structural units include the structural unit (a1) containing an acid-decomposable group whose polarity increases by the action of acid (excluding those corresponding to the structural unit (a0)); the structural unit (a10) represented by general formula (a10-1) described below; the structural unit (a2) containing a lactone-containing cyclic group; and the structural unit (a8) derived from a compound represented by general formula (a8-1) described below.

Regarding the structural unit (a1):
The structural unit (a1) is a structural unit that contains an acid-decomposable group whose polarity increases when acted upon by an acid, with the proviso that structural units that fall under the category of the structural unit (a0) are excluded from the structural unit (a1).

Examples of the acid-dissociable group include those that have been proposed as acid-dissociable groups in base resins for chemically amplified resist compositions.
Specific examples of the acid dissociable group that have been proposed for the base resin of the chemically amplified resist composition include the "acetal type acid dissociable group,""tertiary alkyl ester type acid dissociable group," and "tertiary alkyloxycarbonyl acid dissociable group," which are explained below.

Acetal-type acid-dissociable group:
Among the polar groups, examples of the acid dissociable group protecting a carboxy group or a hydroxyl group include an acid dissociable group represented by the following general formula (a1-r-1) (hereinafter sometimes referred to as an “acetal-type acid dissociable group”).

[In the formula, Ra' ¹ and Ra' ² are a hydrogen atom or an alkyl group. Ra' ³ is a hydrocarbon group, and Ra' ³ may be bonded to either Ra' ¹ or Ra' ² to form a ring.]

In formula (a1-r-1), at least one of ^Ra'1 and ^Ra'2 is preferably a hydrogen atom, and more preferably both are hydrogen atoms.
When ^Ra'1 or ^Ra'2 is an alkyl group, examples of the alkyl group include the same alkyl groups as those exemplified as the substituent that may be bonded to the carbon atom at the α-position in the description of the above α-substituted acrylic acid ester, and an alkyl group having 1 to 5 carbon atoms is preferred. Specifically, preferred examples of the alkyl group include linear or branched alkyl groups. More specific examples include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, and neopentyl groups, and a methyl or ethyl group is more preferred, and a methyl group is particularly preferred.

In formula (a1-r-1), the hydrocarbon group for ^Ra'3 includes a linear or branched alkyl group, or a cyclic hydrocarbon group.
The linear alkyl group preferably has 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms. Specific examples include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-pentyl group. Of these, a methyl group, an ethyl group, or an n-butyl group is preferred, and a methyl group or an ethyl group is more preferred.

The branched alkyl group preferably has 3 to 10 carbon atoms, and more preferably has 3 to 5 carbon atoms. Specific examples include isopropyl, isobutyl, tert-butyl, isopentyl, neopentyl, 1,1-diethylpropyl, and 2,2-dimethylbutyl groups, with isopropyl being preferred.

When ^Ra'3 is a cyclic hydrocarbon group, the hydrocarbon group may be an alicyclic hydrocarbon group or an aromatic hydrocarbon group, and may be a polycyclic group or a monocyclic group.
The monocyclic alicyclic hydrocarbon group is preferably a group in which one hydrogen atom has been removed from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane.
The alicyclic hydrocarbon group that is a polycyclic group is preferably a group in which one hydrogen atom has been removed from a polycycloalkane, and the polycycloalkane preferably has 7 to 12 carbon atoms, and specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

When the cyclic hydrocarbon group of ^Ra'3 is an aromatic hydrocarbon group, the aromatic hydrocarbon group is a hydrocarbon group having at least one aromatic ring.
The aromatic ring is not particularly limited as long as it is a cyclic conjugated system having 4n+2 π electrons, and may be monocyclic or polycyclic. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, further preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms.
Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and aromatic heterocycles in which a part of the carbon atoms constituting the aromatic hydrocarbon ring is replaced with a heteroatom. Examples of the heteroatom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocycle include a pyridine ring and a thiophene ring.
Specific examples of the aromatic hydrocarbon group in ^Ra'3 include a group in which one hydrogen atom has been removed from the aromatic hydrocarbon ring or aromatic heterocycle (aryl group or heteroaryl group); a group in which one hydrogen atom has been removed from an aromatic compound containing two or more aromatic rings (e.g., biphenyl, fluorene, etc.); and a group in which one hydrogen atom of the aromatic hydrocarbon ring or aromatic heterocycle has been substituted with an alkylene group (e.g., arylalkyl groups such as benzyl group, phenethyl group, 1-naphthylmethyl group, 2-naphthylmethyl group, 1-naphthylethyl group, 2-naphthylethyl group, etc.). The alkylene group bonded to the aromatic hydrocarbon ring or aromatic heterocycle preferably has 1 to 4 carbon atoms, more preferably has 1 to 2 carbon atoms, and particularly preferably has 1 carbon atom.

The cyclic hydrocarbon group for ^Ra'3 may have a substituent. Examples of the substituent include -R ^P1 , -R ^P2 -O-R ^P1 , -R P2 -CO-R P1 , -R ^P2 -CO-OR ^P1 , -R ^P2 -O-CO- ^{R P1} ^, -R ^P2 -OH, -R ^P2 -CN or -R ^P2 ^-COOH (hereinafter these substituents are collectively referred to as "Ra ^x5 ").
Here, R ^P1 is a monovalent linear saturated hydrocarbon group having 1 to 10 carbon atoms, a monovalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms. R ^P2 is a single bond, a divalent linear saturated hydrocarbon group having 1 to 10 carbon atoms, a divalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 30 carbon atoms. However, some or all of the hydrogen atoms of the linear saturated hydrocarbon group, the aliphatic cyclic saturated hydrocarbon group, and the aromatic hydrocarbon group of R ^P1 and R ^P2 may be substituted with fluorine atoms. The aliphatic cyclic hydrocarbon group may have one or more of the above-mentioned substituents alone, or may have one or more of each of the above-mentioned substituents.
Examples of the monovalent chain saturated hydrocarbon group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a decyl group.
Examples of the monovalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms include monocyclic aliphatic saturated hydrocarbon groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecyl group, and a cyclododecyl group; and polycyclic aliphatic saturated hydrocarbon groups such as a bicyclo[2.2.2]octanyl group, a tricyclo[5.2.1.02,6]decanyl group, a tricyclo[3.3.1.13,7]decanyl group, a tetracyclo[6.2.1.13,6.02,7]dodecanyl group, and an adamantyl group.
Examples of the monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms include groups in which one hydrogen atom has been removed from an aromatic hydrocarbon ring such as benzene, biphenyl, fluorene, naphthalene, anthracene, and phenanthrene.

When ^Ra'3 is bonded to either ^Ra'1 or ^Ra'2 to form a ring, the cyclic group is preferably a 4- to 7-membered ring, more preferably a 4- to 6-membered ring. Specific examples of the cyclic group include a tetrahydropyranyl group and a tetrahydrofuranyl group.

Tertiary alkyl ester type acid-dissociable group:
Among the above polar groups, examples of the acid-dissociable group that protects the carboxy group include acid-dissociable groups represented by the following general formula (a1-r-2).
Among the acid-dissociable groups represented by the following formula (a1-r-2), those constituted by an alkyl group may be referred to as "tertiary alkyl ester-type acid-dissociable groups" hereinafter for the sake of convenience.

[In the formula, Ra' ⁴ to Ra' ⁶ are each a hydrocarbon group, and Ra' ⁵ and Ra' ⁶ may be bonded to each other to form a ring.]

Examples of the hydrocarbon group for ^Ra'4 include a linear or branched alkyl group, a linear or cyclic alkenyl group, a linear alkynyl group, or a cyclic hydrocarbon group.
Examples of the linear or branched alkyl group and cyclic hydrocarbon group (monocyclic alicyclic hydrocarbon group, polycyclic alicyclic hydrocarbon group, and aromatic hydrocarbon group) in ^Ra'4 are the same as those for ^Ra'3 .
The chain or cyclic alkenyl group for ^Ra'4 is preferably an alkenyl group having 2 to 10 carbon atoms.
Examples of the hydrocarbon group for Ra' ⁵ and Ra' ⁶ include the same as those for Ra' ³ above.

When ^Ra'5 and ^Ra'6 are bonded to each other to form a ring, suitable examples of such a ring include a group represented by the following general formula (a1-r2-1), a group represented by the following general formula (a1-r2-2), and a group represented by the following general formula (a1-r2-3).
On the other hand, when Ra' ⁴ to Ra' ⁶ are not bonded to one another and are independent hydrocarbon groups, suitable examples include groups represented by the following general formula (a1-r2-4).

[In formula (a1-r2-1), Ra' ¹⁰ represents a linear or branched alkyl group having 1 to 12 carbon atoms, some of which may be substituted with a halogen atom or a heteroatom-containing group. Ra' ¹¹ represents a group which forms an aliphatic cyclic group together with the carbon atom to which Ra' ¹⁰ is bonded. In formula (a1-r2-2), Ya represents a carbon atom. Xa represents a group which forms a cyclic hydrocarbon group together with Ya. Some or all of the hydrogen atoms in this cyclic hydrocarbon group may be substituted. Ra ¹⁰¹ to Ra ¹⁰³ are each independently a hydrogen atom, a monovalent linear saturated hydrocarbon group having 1 to 10 carbon atoms, or a monovalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms. Some or all of the hydrogen atoms in this linear saturated hydrocarbon group and aliphatic cyclic saturated hydrocarbon group may be substituted. Two or more of Ra ¹⁰¹ to Ra ¹⁰³ may be bonded to each other to form a cyclic structure. In formula (a1-r2-3), Yaa is a carbon atom. Xaa is a group forming an aliphatic cyclic group together with Yaa. Ra ¹⁰⁴ is an aromatic hydrocarbon group which may have a substituent. In formula (a1-r2-4), Ra' ¹² and Ra' ¹³ are each independently a monovalent chain saturated hydrocarbon group having 1 to 10 carbon atoms. Some or all of the hydrogen atoms in this chain saturated hydrocarbon group may be substituted. Ra' ¹⁴ is a hydrocarbon group which may have a substituent. * indicates a bond (the same applies below).]

In the above formula (a1-r2-1), Ra' ¹⁰ is a linear or branched alkyl group having 1 to 12 carbon atoms which may be partially substituted with a halogen atom or a heteroatom-containing group.

The linear alkyl group for Ra' ¹⁰ has 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, and particularly preferably 1 to 5 carbon atoms.
Examples of the branched alkyl group in ^Ra'10 include the same as those in ^Ra'3 .

The alkyl group in Ra' ¹⁰ may be partially substituted with a halogen atom or a heteroatom-containing group. For example, some of the hydrogen atoms constituting the alkyl group may be substituted with a halogen atom or a heteroatom-containing group. In addition, some of the carbon atoms (e.g., methylene groups) constituting the alkyl group may be substituted with a heteroatom-containing group.
Examples of the heteroatom include an oxygen atom, a sulfur atom, and a nitrogen atom. Examples of the heteroatom-containing group include (-O-), -C(=O)-O-, -O-C(=O)-, -C(=O)-, -O-C(=O)-O-, -C(=O)-NH-, -NH-, -S-, -S(=O) ₂ -, and -S(=O) ₂ -O-.

In formula (a1-r2-1), Ra' ¹¹ (the alicyclic group formed together with the carbon atom to which Ra' ¹⁰ is bonded) is preferably the group exemplified as the monocyclic or polycyclic alicyclic hydrocarbon group (alicyclic hydrocarbon group) for Ra' ³ in formula (a1-r-1). Among these, a monocyclic alicyclic hydrocarbon group is preferred, and specifically, a cyclopentyl group or a cyclohexyl group is more preferred.

In formula (a1-r2-2), examples of the cyclic hydrocarbon group formed by Xa together with Ya include groups in which one or more hydrogen atoms have been further removed from the cyclic monovalent hydrocarbon group (alicyclic hydrocarbon group) in ^Ra'3 in formula (a1-r-1).
The cyclic hydrocarbon group formed by Xa together with Ya may have a substituent. Examples of the substituent include the same substituents as those which the cyclic hydrocarbon group in ^Ra'3 may have.
In formula (a1-r2-2), examples of the monovalent chain saturated hydrocarbon group having 1 to 10 carbon atoms for Ra ¹⁰¹ to Ra ¹⁰³ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a decyl group.
Examples of the monovalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms in Ra ¹⁰¹ to Ra ¹⁰³ include monocyclic aliphatic saturated hydrocarbon groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecyl group, and a cyclododecyl group; and polycyclic aliphatic saturated hydrocarbon groups such as a bicyclo[2.2.2]octanyl group, a tricyclo[5.2.1.02,6]decanyl group, a tricyclo[3.3.1.13,7]decanyl group, a tetracyclo[6.2.1.13,6.02,7]dodecanyl group, and an adamantyl group.
From the viewpoint of ease of synthesis, Ra ¹⁰¹ to Ra ¹⁰³ are preferably a hydrogen atom or a monovalent linear saturated hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrogen atom, a methyl group, or an ethyl group, and particularly preferably a hydrogen atom.

Examples of the substituent that the chain saturated hydrocarbon group or the alicyclic saturated hydrocarbon group represented by the above Ra ¹⁰¹ to Ra ¹⁰³ may have include the same groups as those for the above Ra ^x5 .

Examples of groups containing a carbon-carbon double bond formed by two or more of Ra ¹⁰¹ to Ra ¹⁰³ bonding to each other to form a cyclic structure include a cyclopentenyl group, a cyclohexenyl group, a methylcyclopentenyl group, a methylcyclohexenyl group, a cyclopentylidene-ethenyl group, a cyclohexylidene-ethenyl group, etc. Among these, from the viewpoint of ease of synthesis, a cyclopentenyl group, a cyclohexenyl group, and a cyclopentylidene-ethenyl group are preferred.

In formula (a1-r2-3), the aliphatic cyclic group formed by Xaa together with Yaa is preferably the same as the groups exemplified as the monocyclic or polycyclic alicyclic hydrocarbon group for ^Ra'3 in formula (a1-r-1).
In formula (a1-r2-3), examples of the aromatic hydrocarbon group for Ra ¹⁰⁴ include groups in which one or more hydrogen atoms have been removed from an aromatic hydrocarbon ring having 5 to 30 carbon atoms. Among these, Ra ¹⁰⁴ is preferably a group in which one or more hydrogen atoms have been removed from an aromatic hydrocarbon ring having 6 to 15 carbon atoms, more preferably a group in which one or more hydrogen atoms have been removed from benzene, naphthalene, anthracene, or phenanthrene, even more preferably a group in which one or more hydrogen atoms have been removed from benzene, naphthalene, or anthracene, particularly preferably a group in which one or more hydrogen atoms have been removed from benzene or naphthalene, and most preferably a group in which one or more hydrogen atoms have been removed from benzene.

Examples of the substituent that Ra ¹⁰⁴ in formula (a1-r2-3) may have include a methyl group, an ethyl group, a propyl group, a hydroxyl group, a carboxyl group, a halogen atom, an alkoxy group (such as a methoxy group, an ethoxy group, a propoxy group, or a butoxy group), an alkyloxycarbonyl group, and the like.

In formula (a1-r2-4), Ra' ¹² and Ra' ¹³ are each independently a monovalent chain saturated hydrocarbon group having 1 to 10 carbon atoms. Examples of the monovalent chain saturated hydrocarbon group having 1 to 10 carbon atoms in Ra' ¹² and Ra' ¹³ include the same monovalent chain saturated hydrocarbon groups having 1 to 10 carbon atoms in the above Ra ¹⁰¹ to Ra ^103. Some or all of the hydrogen atoms in this chain saturated hydrocarbon group may be substituted.
Among them, Ra' ¹² and Ra' ¹³ are preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, further preferably a methyl group or an ethyl group, and particularly preferably a methyl group.
When the chain saturated hydrocarbon groups represented by the above Ra'- ¹² and Ra'- ¹³ are substituted, examples of the substituent include the same groups as those for the above Ra ^-x5 .

In formula (a1-r2-4), Ra' ¹⁴ is a hydrocarbon group which may have a substituent. Examples of the hydrocarbon group in Ra' ¹⁴ include a linear or branched alkyl group, and a cyclic hydrocarbon group.

The linear alkyl group for Ra' ¹⁴ preferably has 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2. Specific examples include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-pentyl group. Of these, a methyl group, an ethyl group, or an n-butyl group is preferable, and a methyl group or an ethyl group is more preferable.

The branched alkyl group for Ra' ¹⁴ preferably has 3 to 10 carbon atoms, and more preferably has 3 to 5 carbon atoms. Specific examples include an isopropyl group, an isobutyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a 1,1-diethylpropyl group, and a 2,2-dimethylbutyl group, and is preferably an isopropyl group.

When Ra' ¹⁴ is a cyclic hydrocarbon group, the hydrocarbon group may be an alicyclic hydrocarbon group or an aromatic hydrocarbon group, and may be a polycyclic group or a monocyclic group.
The monocyclic alicyclic hydrocarbon group is preferably a group in which one hydrogen atom has been removed from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane.
The alicyclic hydrocarbon group that is a polycyclic group is preferably a group in which one hydrogen atom has been removed from a polycycloalkane, and the polycycloalkane preferably has 7 to 12 carbon atoms, and specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

Examples of the aromatic hydrocarbon group for Ra' ¹⁴ include the same as the aromatic hydrocarbon group for Ra ^104. Among them, Ra' ¹⁴ is preferably a group in which one or more hydrogen atoms have been removed from an aromatic hydrocarbon ring having 6 to 15 carbon atoms, more preferably a group in which one or more hydrogen atoms have been removed from benzene, naphthalene, anthracene or phenanthrene, still more preferably a group in which one or more hydrogen atoms have been removed from benzene, naphthalene or anthracene, particularly preferably a group in which one or more hydrogen atoms have been removed from naphthalene or anthracene, and most preferably a group in which one or more hydrogen atoms have been removed from naphthalene.
Examples of the substituent which Ra' ¹⁴ may have include the same substituents as those which Ra ¹⁰⁴ may have.

When Ra' ¹⁴ in formula (a1-r2-4) is a naphthyl group, the position at which it bonds to the tertiary carbon atom in formula (a1-r2-4) may be either the 1st or 2nd position of the naphthyl group.
When Ra' ¹⁴ in formula (a1-r2-4) is an anthryl group, the position at which it bonds to the tertiary carbon atom in formula (a1-r2-4) may be any one of the 1-position, 2-position or 9-position of the anthryl group.

Specific examples of the group represented by formula (a1-r2-1) are given below.

Specific examples of the group represented by formula (a1-r2-2) are given below.

Specific examples of the group represented by the formula (a1-r2-3) are given below.

Specific examples of the group represented by formula (a1-r2-4) are given below.

Tertiary alkyloxycarbonyl acid dissociating group:
Among the polar groups, examples of the acid dissociable group that protects the hydroxyl group include acid dissociable groups represented by the following general formula (a1-r-3) (hereinafter, for convenience, may be referred to as “tertiary alkyloxycarbonyl acid dissociable group”).

[In the formula, Ra' ⁷ to Ra' ⁹ each represent an alkyl group.]

In formula (a1-r-3), Ra' ⁷ to Ra' ⁹ are each preferably an alkyl group having 1 to 5 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms.
The total number of carbon atoms in each alkyl group is preferably 3 to 7, more preferably 3 to 5, and most preferably 3 or 4.

Secondary alkyl ester type acid-dissociable group:
Among the above polar groups, examples of the acid-dissociable group that protects the carboxy group include acid-dissociable groups represented by the following general formula (a1-r-4).

[In the formula, ^Ra'10 is a hydrocarbon group. ^Ra'11a and ^Ra'11b are each independently a hydrogen atom, a halogen atom or an alkyl group. ^Ra'12 is a hydrogen atom or a hydrocarbon group. ^Ra'10 and ^Ra'11a or ^Ra'11b may be bonded to each other to form a ring. ^Ra'11a or ^Ra'11b and ^Ra'12 may be bonded to each other to form a ring.]

In the formula, examples of the hydrocarbon group in ^Ra'10 and ^Ra'12 include the same as those in ^Ra'3 above.
In the formula, examples of the alkyl group in ^Ra'11a and ^Ra'11b include the same as the alkyl group in ^Ra'1 .
In the formula, the hydrocarbon groups in ^Ra'10 and ^Ra'12 and the alkyl groups in ^Ra'11a and ^Ra'11b may have a substituent. Examples of the substituent include the above-mentioned ^Rax5 .

^Ra'10 and ^Ra'11a or ^Ra'11b may be bonded to each other to form a ring. The ring may be a polycyclic or monocyclic ring, an alicyclic or aromatic ring.
The alicyclic and aromatic rings may contain heteroatoms.

The ring formed by ^Ra'10 and ^Ra'11a or ^Ra'11b bonding to each other is preferably a monocycloalkene, a ring in which a part of the carbon atoms of a monocycloalkene is substituted with a heteroatom (oxygen atom, sulfur atom, etc.), or a monocycloalkadiene, more preferably a cycloalkene having 3 to 6 carbon atoms, and more preferably cyclopentene or cyclohexene.

The ring formed by bonding ^Ra'10 and ^Ra'11a or ^Ra'11b to each other may be a condensed ring. Specific examples of the condensed ring include indan.

The ring formed by bonding ^Ra'10 and ^Ra'11a or ^Ra'11b together may have a substituent. Examples of the substituent include the above-mentioned ^Rax5 .

^Ra'11a or ^Ra'11b and ^Ra'12 may be bonded to each other to form a ring, and examples of such a ring include the same as the ring formed by ^Ra'10 and ^Ra'11a or ^Ra'11b being bonded to each other.

Specific examples of the group represented by formula (a1-r-4) are given below.

Examples of the structural unit (a1) include structural units derived from acrylic esters in which the hydrogen atom bonded to the carbon atom at the α-position may be substituted with a substituent, structural units derived from acrylamide, structural units in which at least some of the hydrogen atoms in the hydroxyl groups of a structural unit derived from hydroxystyrene or a hydroxystyrene derivative are protected with a substituent containing the acid-decomposable group, and structural units in which at least some of the hydrogen atoms in -C(=O)-OH of a structural unit derived from vinylbenzoic acid or a vinylbenzoic acid derivative are protected with a substituent containing the acid-decomposable group.

Of the above, the structural unit (a1) is preferably a structural unit derived from an acrylate ester in which the hydrogen atom bonded to the carbon atom at the α-position may be substituted with a substituent.
Preferred specific examples of the structural unit (a1) include structural units represented by general formula (a1-1) or (a1-2) shown below.

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. Va ¹ is a divalent hydrocarbon group which may have an ether bond. n _a1 is an integer of 0 to 2. Ra ¹ is an acid dissociable group represented by the above general formula (a1-r-1) or (a1-r-2). Wa ¹ is n _a2 +1 valent hydrocarbon group, n _a2 is an integer of 1 to 3, and Ra ² is an acid dissociable group represented by the above general formula (a1-r-1) or (a1-r-3).]

In the formula (a1-1), the alkyl group having 1 to 5 carbon atoms represented by R is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. The halogenated alkyl group having 1 to 5 carbon atoms is a group in which some or all of the hydrogen atoms of the alkyl group having 1 to 5 carbon atoms are substituted with halogen atoms. As the halogen atom, a fluorine atom is particularly preferable.
R is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms, and from the viewpoint of industrial availability, a hydrogen atom or a methyl group is most preferred.

In the above formula (a1-1), the divalent hydrocarbon group for ^Va1 may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group.

The aliphatic hydrocarbon group as the divalent hydrocarbon group in ^Va1 may be saturated or unsaturated, and is usually preferably saturated.
More specifically, the aliphatic hydrocarbon group may be a straight-chain or branched-chain aliphatic hydrocarbon group, or an aliphatic hydrocarbon group containing a ring in the structure.

The linear aliphatic hydrocarbon group preferably contains 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, even more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.
As the straight-chain aliphatic hydrocarbon group, a straight-chain alkylene group is preferable, and specific examples thereof include a methylene group [-CH ₂ -], an ethylene group [-(CH ₂ ) ₂ -], a trimethylene group [-(CH ₂ ) ₃ -], a tetramethylene group [-(CH ₂ ) ₄ -], a pentamethylene group [-(CH ₂ ) ₅ -], etc.
The branched aliphatic hydrocarbon group preferably has 2 to 10 carbon atoms, more preferably has 3 to 6 carbon atoms, even more preferably has 3 or 4 carbon atoms, and most preferably has 3 carbon atoms.
The branched aliphatic hydrocarbon group is preferably a branched alkylene group, and specific examples thereof _include alkylmethylene groups such as -CH( _CH3 )-, -CH( _CH2CH3 )-, -C( _CH3 ) _2- _{, -C(CH3)(CH2CH3)-, -C(CH3)(CH2CH2CH3)-, and -C(CH2CH3} ₎ _2- _; _{alkylethylene} _groups _such _as _-CH ₍ _CH3 ₎ _CH2- _, -CH( _CH3 )CH( _CH3 ) _- , -C( _CH3 ) _2CH2- _, -CH ₍ _CH2CH3 ) _CH2- _, and -C( _CH2CH3 ) ₂ _- _CH2- _; and alkyl alkylene groups such as alkyl trimethylene groups such as _-CH (CH ₃ )CH ₂ CH ₂ CH ₂ -, -CH ₂ CH(CH ₃ )CH ₂ CH ₂ -, etc. The alkyl group in the alkyl alkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

Examples of the aliphatic hydrocarbon group containing a ring in the structure include an alicyclic hydrocarbon group (a group in which two hydrogen atoms have been removed from an aliphatic hydrocarbon ring), a group in which an alicyclic hydrocarbon group is bonded to the end of a linear or branched aliphatic hydrocarbon group, a group in which an alicyclic hydrocarbon group is interposed in the middle of a linear or branched aliphatic hydrocarbon group, etc. Examples of the linear or branched aliphatic hydrocarbon group include the same as the linear aliphatic hydrocarbon group or the branched aliphatic hydrocarbon group.
The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably has 3 to 12 carbon atoms.
The alicyclic hydrocarbon group may be polycyclic or monocyclic. The monocyclic alicyclic hydrocarbon group is preferably a group in which two hydrogen atoms have been removed from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane. The polycyclic alicyclic hydrocarbon group is preferably a group in which two hydrogen atoms have been removed from a polycycloalkane, and the polycycloalkane preferably has 7 to 12 carbon atoms, and specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

The aromatic hydrocarbon group as the divalent hydrocarbon group in ^Va1 is a hydrocarbon group having an aromatic ring.
The aromatic hydrocarbon group preferably has 3 to 30 carbon atoms, more preferably 5 to 30, even more preferably 5 to 20, particularly preferably 6 to 15, and most preferably 6 to 12. However, this number of carbon atoms does not include the number of carbon atoms in the substituents.
Specific examples of the aromatic ring contained in the aromatic hydrocarbon group include aromatic hydrocarbon rings such as benzene, biphenyl, fluorene, naphthalene, anthracene, and phenanthrene; aromatic heterocycles in which a part of the carbon atoms constituting the aromatic hydrocarbon ring is substituted with a heteroatom, etc. Examples of the heteroatom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom.
Specific examples of the aromatic hydrocarbon group include a group in which two hydrogen atoms have been removed from the aromatic hydrocarbon ring (arylene group); a group in which one hydrogen atom of a group in which one hydrogen atom has been removed from the aromatic hydrocarbon ring (aryl group) has been substituted with an alkylene group (for example, a group in which one hydrogen atom has been further removed from the aryl group in an arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethyl group). The number of carbon atoms in the alkylene group (the alkyl chain in the arylalkyl group) is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1.

In the formula (a1-1), Ra ¹ is an acid-dissociable group represented by the formula (a1-r-1) or (a1-r-2).

In the formula (a1-2), the n _a2 +1 valent hydrocarbon group in Wa ¹ may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. The aliphatic hydrocarbon group means a hydrocarbon group that does not have aromaticity, and may be saturated or unsaturated, and is usually preferably saturated. Examples of the aliphatic hydrocarbon group include linear or branched aliphatic hydrocarbon groups, aliphatic hydrocarbon groups containing a ring in the structure, and groups that combine linear or branched aliphatic hydrocarbon groups with aliphatic hydrocarbon groups containing a ring in the structure.
The n _a2 +1 valency is preferably divalent to tetravalent, and more preferably divalent or trivalent.

In the formula (a1-2), ^Ra2 is an acid-dissociable group represented by the above general formula (a1-r-1) or (a1-r-3).

Specific examples of the structural unit (a1) are shown below: In each of the following formulas, R ^α represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

The structural unit (a1) contained in the component (A1) may be of one type, or two or more types.
As the structural unit (a1), a structural unit represented by the above formula (a1-1) is more preferable, since it is easier to improve properties (CDU, etc.) in electron beam or EUV lithography.

[In the formula, Ra ¹ ″ is an acid-dissociable group represented by general formula (a1-r2-1), (a1-r2-3) or (a1-r2-4). * represents a bond.]

In the formula (a1-1-1), R, ^Va1 and n _a1 are the same as R, ^Va1 and n _a1 in the formula (a1-1).
The acid dissociable group represented by formula (a1-r2-1), (a1-r2-3) or (a1-r2-4) is as described above. Among them, it is preferable to select an acid dissociable group that is a cyclic group, since it is suitable for use with EB or EUV and can enhance reactivity, and an acid dissociable group represented by formula (a1-r2-1) is more preferable.

When the component (A1) contains the structural unit (a1), the proportion of the structural unit (a1) in the component (A1) is preferably 5 to 95 mol %, more preferably 10 to 90 mol %, even more preferably 30 to 70 mol %, and particularly preferably 40 to 60 mol %, based on the total (100 mol %) of all structural units constituting the component (A1).
By ensuring that the proportion of the structural unit (a1) is at least as large as the lower limit of the aforementioned preferred range, lithography properties such as sensitivity, CDU, resolution, and roughness can be improved. On the other hand, when the proportion is at most the upper limit of the aforementioned preferred range, a balance with other structural units can be achieved, resulting in various favorable lithography properties.

Regarding the structural unit (a10):
The structural unit (a10) is a structural unit represented by general formula (a10-1) shown below (however, this does not include those that correspond to the structural unit (a1)).

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. Ya ^x1 is a single bond or a divalent linking group. Wa ^x1 is an aromatic hydrocarbon group which may have a substituent. n _ax1 is an integer of 1 or more.]

In the above formula (a10-1), R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms.
R is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms, and from the viewpoint of industrial availability, a hydrogen atom, a methyl group, or a trifluoromethyl group is more preferable, a hydrogen atom or a methyl group is still more preferable, and a hydrogen atom is particularly preferable.

In the above formula (a10-1), Ya ^x1 represents a single bond or a divalent linking group.
In the above chemical formula, the divalent linking group for Ya ^x1 is not particularly limited, but suitable examples include a divalent hydrocarbon group which may have a substituent, and a divalent linking group containing a hetero atom.

Ya ^x1 is preferably a single bond, an ester bond [-C(=O)-O-, -O-C(=O)-], an ether bond (-O-), a linear or branched alkylene group, or a combination thereof, and more preferably a single bond or an ester bond [-C(=O)-O-, -O-C(=O)-].

In the above formula (a10-1), Wa ^x1 represents an aromatic hydrocarbon group which may have a substituent.
The aromatic hydrocarbon group in Wa ^x1 may be a group in which (n _ax1 +1) hydrogen atoms have been removed from an aromatic ring which may have a substituent. The aromatic ring here is not particularly limited as long as it is a cyclic conjugated system having 4n+2 π electrons. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, even more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms. Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and aromatic heterocycles in which a part of the carbon atoms constituting the aromatic hydrocarbon ring is substituted with a heteroatom. Examples of the heteroatom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocycle include a pyridine ring and a thiophene ring.
Further, examples of the aromatic hydrocarbon group in Wa ^x1 include groups in which (n _ax1 +1) hydrogen atoms have been removed from an aromatic compound containing an aromatic ring which may have two or more substituents (e.g., biphenyl, fluorene, etc.).
Among the above, Wa ^x1 is preferably a group in which (n _ax1 +1) hydrogen atoms have been removed from benzene, naphthalene, anthracene or biphenyl, more preferably a group in which (n _ax1 +1) hydrogen atoms have been removed from benzene or naphthalene, and even more preferably a group in which (n _ax1 +1) hydrogen atoms have been removed from benzene.

The aromatic hydrocarbon group in Wa ^x1 may or may not have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, and a halogenated alkyl group. Examples of the alkyl group, alkoxy group, halogen atom, and halogenated alkyl group as the substituent include the same as those exemplified as the substituent of the cyclic alicyclic hydrocarbon group in Ya ^x1 . The substituent is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, more preferably a linear or branched alkyl group having 1 to 3 carbon atoms, further preferably an ethyl group or a methyl group, and particularly preferably a methyl group. It is preferable that the aromatic hydrocarbon group in Wa ^x1 does not have a substituent.

In the formula (a10-1), n _ax1 represents an integer of 1 or more, preferably an integer of 1 to 10, more preferably an integer of 1 to 5, still more preferably 1, 2 or 3, and particularly preferably 1 or 2.

Specific examples of the structural unit (a10) represented by the aforementioned formula (a10-1) are shown below.
In each of the following formulas, R ^α represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

The structural unit (a10) contained in the component (A1) may be of one type, or two or more types.
When the component (A1) contains the structural unit (a10), the proportion of the structural unit (a10) in the component (A1) is preferably 20 to 60 mol %, more preferably 25 to 55 mol %, even more preferably 30 to 50 mol %, and particularly preferably 35 to 45 mol %, based on the total (100 mol %) of all structural units constituting the component (A1).
By ensuring that the proportion of the structural unit (a10) is at least as large as the lower limit of the above range, sensitivity can be further improved, while by ensuring that the proportion is at most the upper limit of the above range, it is easier to achieve a balance with other structural units.

Regarding the structural unit (a2):
The component (A1) may further include a structural unit (a2) that contains a lactone-containing cyclic group (provided that this does not correspond to the structural unit (a1)).
The lactone-containing cyclic group of the structural unit (a2) is effective in improving the adhesion of the resist film to the substrate when the component (A1) is used to form a resist film. In addition, the structural unit (a2) has the effects of, for example, appropriately adjusting the acid diffusion length, improving the adhesion of the resist film to the substrate, and appropriately adjusting the solubility during development, thereby improving the lithography properties, etc.

A "lactone-containing cyclic group" refers to a cyclic group that contains a ring (lactone ring) that contains --O--C(=O)-- in its ring skeleton. The lactone ring is counted as the first ring, and when there is only a lactone ring, it is called a monocyclic group, and when there is further contained another ring structure, it is called a polycyclic group regardless of the structure. The lactone-containing cyclic group may be a monocyclic group or a polycyclic group.
The lactone-containing cyclic group in the structural unit (a2) is not particularly limited and any suitable group can be used. Specific examples include the groups represented by the following general formulae (a2-r-1) to (a2-r-7).

[In the formula, Ra' ²¹ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, -COOR", -OC(=O)R", a hydroxyalkyl group or a cyano group; R" is a hydrogen atom, an alkyl group or a lactone-containing cyclic group; A" is an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom (-O-) or a sulfur atom (-S-), an oxygen atom or a sulfur atom, n' is an integer of 0 to 2, and m' is 0 or 1. * represents a bond (the same applies hereinafter).]

In the general formulae (a2-r-1) to (a2-r-7), the alkyl group in ^Ra'21 is preferably an alkyl group having 1 to 6 carbon atoms. The alkyl group is preferably linear or branched. Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and a hexyl group. Of these, a methyl group or an ethyl group is preferred, and a methyl group is particularly preferred.
The alkoxy group in Ra' ²¹ is preferably an alkoxy group having 1 to 6 carbon atoms. The alkoxy group is preferably linear or branched. Specific examples include groups in which the alkyl groups listed above as the alkyl groups in Ra' ²¹ are linked to an oxygen atom (-O-).
The halogen atom in ^Ra'21 is preferably a fluorine atom.
The halogenated alkyl group in Ra' ²¹ may be a group in which some or all of the hydrogen atoms in the alkyl group in Ra' ²¹ have been substituted with the halogen atoms. As the halogenated alkyl group, a fluorinated alkyl group is preferable, and a perfluoroalkyl group is particularly preferable.

In --COOR" and --OC(.dbd.O)R" in Ra' ²¹ , R" is both a hydrogen atom, an alkyl group, or a lactone-containing cyclic group.
The alkyl group for R″ may be linear, branched, or cyclic, and preferably has 1 to 15 carbon atoms.
When R″ is a linear or branched alkyl group, it preferably has 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms, and is particularly preferably a methyl group or an ethyl group.
When R" is a cyclic alkyl group, it preferably has 3 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specific examples include groups in which one or more hydrogen atoms have been removed from a monocycloalkane which may or may not be substituted with a fluorine atom or a fluorinated alkyl group; and groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as a bicycloalkane, tricycloalkane, or tetracycloalkane. More specific examples include groups in which one or more hydrogen atoms have been removed from a monocycloalkane such as cyclopentane or cyclohexane; and groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane.
Examples of the lactone-containing cyclic group for R″ include the same groups as those represented by the general formulae (a2-r-1) to (a2-r-7).
The hydroxyalkyl group in Ra' ²¹ preferably has 1 to 6 carbon atoms, and specific examples include the alkyl group in Ra' ²¹ in which at least one hydrogen atom has been substituted with a hydroxyl group.

Among the above, it is preferable that ^Ra'21 each independently represents a hydrogen atom or a cyano group.

In the general formulae (a2-r-2), (a2-r-3) and (a2-r-5), the alkylene group having 1 to 5 carbon atoms in A" is preferably a straight-chain or branched-chain alkylene group, such as a methylene group, an ethylene group, an n-propylene group or an isopropylene group. When the alkylene group contains an oxygen atom or a sulfur atom, specific examples thereof include groups in which -O- or -S- is present at the terminal or between the carbon atoms of the alkylene group, such as -O-CH ₂ -, -CH ₂ -O-CH ₂ -, -S-CH ₂ - and -CH ₂ -S-CH ₂ -. A" is preferably an alkylene group having 1 to 5 carbon atoms or -O-, more preferably an alkylene group having 1 to 5 carbon atoms, and most preferably a methylene group.

Specific examples of the groups represented by general formulas (a2-r-1) to (a2-r-7) are listed below.

Of the various possibilities, the structural unit (a2) is preferably a structural unit derived from an acrylate ester in which the hydrogen atom bonded to the carbon atom at the α-position may be substituted with a substituent.
The structural unit (a2) is preferably a structural unit represented by general formula (a2-1) shown below.

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. Ya ²¹ is a single bond or a divalent linking group. La ²¹ is -O-, -COO-, -CON(R')-, -OCO-, -CONHCO-, or -CONHCS-, and R' represents a hydrogen atom or a methyl group. However, when La ²¹ is -O-, Ya ²¹ does not become -CO-. Ra ²¹ is a lactone-containing cyclic group.]

In the formula (a2-1), R is the same as above. R is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms, and from the viewpoint of industrial availability, a hydrogen atom or a methyl group is particularly preferred.

In the formula (a2-1), the divalent linking group for Ya ²¹ is not particularly limited, but suitable examples include a divalent hydrocarbon group which may have a substituent, and a divalent linking group containing a hetero atom.

Ya ²¹ is preferably a single bond, an ester bond [--C(.dbd.O)--O--], an ether bond (--O--), a linear or branched alkylene group, or a combination thereof.

In the formula (a2-1), it is preferable that Ya ²¹ is a single bond, and La ²¹ is --COO-- or --OCO--.

In the above formula (a2-1), Ra ²¹ represents a lactone-containing cyclic group.
Suitable examples of the lactone-containing cyclic group for Ra ²¹ include the groups represented by the above-mentioned general formulae (a2-r-1) to (a2-r-7), respectively.

The structural unit (a2) contained in the component (A1) may be of one type, or two or more types.
When the component (A1) contains the structural unit (a2), the proportion of the structural unit (a2) is preferably 1 to 20 mol %, more preferably 1 to 15 mol %, and even more preferably 1 to 10 mol %, based on the total (100 mol %) of all structural units constituting the component (A1).
When the proportion of the structural unit (a2) is at least as large as the preferable lower limit, the effects achieved by including the structural unit (a2) can be fully obtained due to the effects described above. When the proportion of the structural unit (a2) is no more than the upper limit, a balance with other structural units can be achieved, and various lithography properties become favorable.

Regarding the structural unit (a8):
The structural unit (a8) is a structural unit derived from a compound represented by general formula (a8-1) shown below.
However, those corresponding to the structural unit (a0) are excluded.

[Wherein, ^W2 is a polymerizable group-containing group. ^Yax2 is a single bond or a (n _ax2 +1)-valent linking group. ^Yax2 and ^W2 may form a condensed ring. ^R1 is a fluorinated alkyl group having 1 to 12 carbon atoms. ^R2 is an organic group having 1 to 12 carbon atoms which may have a fluorine atom or a hydrogen atom. ^R2 and ^Yax2 may be bonded to each other to form a ring structure. n _ax2 is an integer of 1 to 3.]

The "polymerizable group" in the polymerizable group-containing group of ^W2 is a group that enables a compound having a polymerizable group to be polymerized by radical polymerization or the like, and is, for example, a group that contains a multiple bond between carbon atoms, such as an ethylenic double bond.

The polymerizable group-containing group may be a group composed only of a polymerizable group, or may be a group composed of a polymerizable group and a group other than the polymerizable group. Examples of the group other than the polymerizable group include a divalent hydrocarbon group which may have a substituent, and a divalent linking group containing a hetero atom.
A suitable example of the polymerizable group-containing group is a group represented by the chemical formula: C(R ^x11 )(R ^x12 )=C(R ^x13 )-Ya ^x0 -.
In this chemical formula, R ^X11 , R ^X12 and R ^X13 each represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, and Ya ^x0 represents a single bond or a divalent linking group.

Examples of the fused ring formed by Ya ^x2 and ^W2 include a fused ring formed by the polymerizable group at the ^W2 site and Ya ^x2 , and a fused ring formed by Ya ^x2 and a group other than the polymerizable group at the ^W2 site.
The fused ring formed by Ya ^x2 and W ² may have a substituent.

Specific examples of the structural unit (a8) are shown below.
In the following formula, R ^α represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

Among the above examples, the structural unit (a8) is preferably at least one selected from the group consisting of structural units represented by the chemical formulas (a8-1-01) to (a8-1-04), (a8-1-06), (a8-1-08), (a8-1-09), and (a8-1-10), and more preferably at least one selected from the group consisting of structural units represented by the chemical formulas (a8-1-01) to (a8-1-04), and (a8-1-09).

The structural unit (a8) contained in the component (A1) may be of one type, or two or more types.
The amount of the structural unit (a8) in the component (A1) relative to the total amount (100 mol %) of all structural units constituting the component (A1), is preferably no more than 50 mol %, and more preferably from 0 to 30 mol %.

The component (A1) contained in the resist composition may use either a single type of compound, or a combination of two or more types of compounds.
In the resist composition of this embodiment, the component (A1) can be a polymeric compound that has a repeating structure of the structural unit (a0).
Among the above, suitable examples of the component (A1) include polymeric compounds that include a repeating structure of the structural unit (a0) and the structural unit (a10).

In polymeric compounds having a repeating structure of the structural unit (a0) and the structural unit (a10), the proportion of the structural unit (a0) relative to the total amount (100 mol%) of all structural units constituting the polymeric compound is preferably 40 to 80 mol%, more preferably 45 to 75 mol%, even more preferably 50 to 70 mol%, and particularly preferably 55 to 65 mol%.
Furthermore, the proportion of the structural unit (a10) in the polymer compound is preferably from 20 to 60 mol%, more preferably from 25 to 55 mol%, even more preferably from 30 to 50 mol%, and particularly preferably from 35 to 45 mol%, based on the total (100 mol%) of all structural units constituting the polymer compound.

The component (A1) can be produced by dissolving monomers from which each structural unit is derived in a polymerization solvent, and then adding a radical polymerization initiator such as azobisisobutyronitrile (AIBN) or dimethyl azobisisobutyrate (e.g., V-601), and polymerizing the resulting mixture.
Alternatively, the component (A1) can be produced by dissolving a monomer that derives the structural unit (a0) and, if necessary, a monomer that derives a structural unit other than the structural unit (a0) (for example, the structural unit (a10)) in a polymerization solvent, adding the above-mentioned radical polymerization initiator to the resulting solution to polymerize, and then carrying out a deprotection reaction.
During polymerization, a chain transfer agent such as HS-CH ₂ -CH ₂ -CH ₂ -C(CF ₃ ) ₂ -OH may be used in combination to introduce a -C(CF ₃ ) ₂ -OH group to the end. A copolymer having a hydroxyalkyl group in which some of the hydrogen atoms of the alkyl group are substituted with fluorine atoms in this way is effective in reducing development defects and LER (line edge roughness: non-uniform unevenness of the line sidewalls).

The weight average molecular weight (Mw) of the component (A1) (based on polystyrene equivalent by gel permeation chromatography (GPC)) is not particularly limited, but is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, and even more preferably 3,000 to 20,000.
When the Mw of the component (A1) is no more than the preferred upper limit of this range, the compound has sufficient solubility in a resist solvent for use as a resist, and when it is no less than the preferred lower limit of this range, the compound has good dry etching resistance and good cross-sectional shape of the resist pattern.
The dispersity (Mw/Mn) of the component (A1) is not particularly limited, but is preferably from 1.0 to 4.0, more preferably from 1.0 to 3.0, and particularly preferably from 1.0 to 2.0, where Mn represents the number average molecular weight.

Regarding the Component (A2) The resist composition of this embodiment may also use, as the component (A), a base component (A2) (hereafter referred to as the component (A2)) that does not fall under the category of the component (A1) above and whose solubility in a developer changes under the action of an acid.
There are no particular restrictions on the component (A2), and it may be any compound selected from the many compounds conventionally known as base components for chemically amplified resist compositions.
The component (A2) may be a polymeric compound or a low molecular weight compound, and may be a combination of two or more of these.

The proportion of component (A1) in component (A) is preferably 25% by mass or more, more preferably 50% by mass or more, even more preferably 75% by mass or more, and may be 100% by mass, based on the total mass of component (A). If the proportion is 25% by mass or more, a resist pattern that is excellent in various lithography properties such as high sensitivity, resolution, and improved roughness is easily formed.

The content of component (A) in the resist composition of this embodiment may be adjusted according to the thickness of the resist film to be formed, etc.

<Other ingredients>
The resist composition of this embodiment may further contain other components in addition to the above-mentioned components (A) and (B). Examples of the other components include the following components (B), (D), (E), (F), and (S).

<Acid generator component (B)>
The resist composition of this embodiment preferably further contains an acid generator component (B) that generates an acid upon exposure.
There are no particular limitations on the component (B), and any of the acid generators that have been proposed so far for use in chemically amplified resist compositions can be used.
Examples of such acid generators include onium salt-based acid generators such as iodonium salts and sulfonium salts, oxime sulfonate-based acid generators, diazomethane-based acid generators such as bisalkyl- or bisarylsulfonyl diazomethanes and poly(bissulfonyl) diazomethanes, nitrobenzylsulfonate-based acid generators, iminosulfonate-based acid generators, and disulfone-based acid generators.

Examples of onium salt acid generators include a compound represented by the following general formula (b-1) (hereinafter also referred to as "component (b-1)"), a compound represented by general formula (b-2) (hereinafter also referred to as "component (b-2)"), or a compound represented by general formula (b-3) (hereinafter also referred to as "component (b-3)").

[In the formula, R ¹⁰¹ and R ¹⁰⁴ to R ¹⁰⁸ are each independently a cyclic group which may have a substituent, a chain alkyl group which may have a substituent, or a chain alkenyl group which may have a substituent. R ¹⁰⁴ and R ¹⁰⁵ may be bonded to each other to form a ring structure. R ¹⁰² is a fluorinated alkyl group having 1 to 5 carbon atoms or a fluorine atom. Y ¹⁰¹ is a divalent linking group containing an oxygen atom or a single bond. V ¹⁰¹ to V ¹⁰³ are each independently a single bond, an alkylene group, or a fluorinated alkylene group. L ¹⁰¹ to L ¹⁰² are each independently a single bond or an oxygen atom. L ¹⁰³ to L ¹⁰⁵ are each independently a single bond, -CO-, or -SO ₂ -. m is an integer of 1 or more, and M' ^m+ is an m-valent onium cation.]

{anion portion}
Anion in Component (b-1) In formula (b-1), R ¹⁰¹ represents a cyclic group which may have a substituent, a chain alkyl group which may have a substituent, or a chain alkenyl group which may have a substituent.

Optionally substituted cyclic group:
The cyclic group is preferably a cyclic hydrocarbon group, and the cyclic hydrocarbon group may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group. An aliphatic hydrocarbon group means a hydrocarbon group that does not have aromaticity. In addition, the aliphatic hydrocarbon group is preferably saturated.

The aromatic hydrocarbon group for R ¹⁰¹ is a hydrocarbon group having an aromatic ring. The number of carbon atoms in the aromatic hydrocarbon group is preferably 3 to 30, more preferably 5 to 30, even more preferably 5 to 20, particularly preferably 6 to 15, and most preferably 6 to 10. However, this number of carbon atoms does not include the number of carbon atoms in the substituent.
Specific examples of the aromatic ring contained in the aromatic hydrocarbon group of R ¹⁰¹ include benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, and aromatic heterocycles in which a part of the carbon atoms constituting these aromatic rings are substituted with heteroatoms, etc. Examples of the heteroatom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom.
Specific examples of the aromatic hydrocarbon group for R ¹⁰¹ include a group in which one hydrogen atom has been removed from the aromatic ring (aryl group: for example, a phenyl group, a naphthyl group, etc.), a group in which one hydrogen atom of the aromatic ring has been substituted with an alkylene group (for example, a benzyl group, a phenethyl group, a 1-naphthylmethyl group, etc.), etc. The number of carbon atoms in the alkylene group (the alkyl chain in the arylalkyl group) is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1.

The cyclic aliphatic hydrocarbon group for R ¹⁰¹ includes an aliphatic hydrocarbon group containing a ring in the structure.
Examples of the aliphatic hydrocarbon group containing a ring in its structure include alicyclic hydrocarbon groups (groups in which one hydrogen atom has been removed from an aliphatic hydrocarbon ring), groups in which an alicyclic hydrocarbon group is bonded to the end of a straight-chain or branched-chain aliphatic hydrocarbon group, and groups in which an alicyclic hydrocarbon group is present in the middle of a straight-chain or branched-chain aliphatic hydrocarbon group.
The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably has 3 to 12 carbon atoms.
The alicyclic hydrocarbon group may be a polycyclic group or a monocyclic group. The monocyclic alicyclic hydrocarbon group is preferably a group obtained by removing one or more hydrogen atoms from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane. The polycyclic alicyclic hydrocarbon group is preferably a group obtained by removing one or more hydrogen atoms from a polycycloalkane, and the polycycloalkane preferably has 7 to 30 carbon atoms. Among them, the polycycloalkane is more preferably a polycycloalkane having a polycyclic skeleton of a bridged ring system such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane; or a polycycloalkane having a polycyclic skeleton of a condensed ring system such as a cyclic group having a steroid skeleton.

Among these, the cyclic aliphatic hydrocarbon group for R ¹⁰¹ is preferably a group in which one or more hydrogen atoms have been removed from a monocycloalkane or polycycloalkane, more preferably a group in which one hydrogen atom has been removed from a polycycloalkane, further preferably an adamantyl group or a norbornyl group, and particularly preferably an adamantyl group.

The linear aliphatic hydrocarbon group which may be bonded to the alicyclic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6, even more preferably 1 to 4, and most preferably 1 to 3. As the linear aliphatic hydrocarbon group, linear alkylene groups are preferred, and specific examples thereof include a methylene group [-CH ₂ -], an ethylene group [-(CH ₂ ) ₂ -], a trimethylene group [-(CH ₂ ) ₃ -], a tetramethylene group [-(CH ₂ ) ₄ -], a pentamethylene group [-(CH ₂ ) ₅ -], and the like.
The branched aliphatic hydrocarbon group which may be bonded to the alicyclic hydrocarbon group preferably has 2 to 10 carbon atoms, more preferably 3 to 6 carbon atoms, even more preferably 3 or 4 carbon atoms, and most preferably 3 carbon atoms. The branched aliphatic hydrocarbon group is preferably a branched alkylene group, and specific examples thereof _include alkylmethylene groups such as -CH( _CH3 )-, -CH( _CH2CH3 )-, -C( _CH3 ) _2- _{, -C(CH3)(CH2CH3)-, -C(CH3)(CH2CH2CH3)-, and -C(CH2CH3} ₎ _2- _; _{alkylethylene} _groups _such _as _-CH ₍ _CH3 ₎ _CH2- _, -CH( _CH3 )CH( _CH3 ) _- , -C( _CH3 ) _2CH2- _, -CH ₍ _CH2CH3 ) _CH2- _, and -C( _CH2CH3 ) ₂ _- _CH2- _; and alkyl alkylene groups such as alkyl trimethylene groups such as _-CH (CH ₃ )CH ₂ CH ₂ CH ₂ -, -CH ₂ CH(CH ₃ )CH ₂ CH ₂ -, etc. The alkyl group in the alkyl alkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

Furthermore, the cyclic hydrocarbon group in R ¹⁰¹ may contain a heteroatom, such as a heterocycle. Specific examples include the lactone-containing cyclic groups represented by the above general formulae (a2-r-1) to (a2-r-7), the -SO ₂ -containing cyclic groups represented by the following general formulae (b5-r-1) to (b5-r-4), and other heterocyclic groups represented by the following chemical formulae (r-hr-1) to (r-hr-16). In the formulae, * represents a bond bonded to Y ¹⁰¹ in formula (b-1).

[In the formula, Rb' ⁵¹ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, -COOR", -OC(=O)R", a hydroxyalkyl group or a cyano group; R" is a hydrogen atom, an alkyl group, a lactone-containing cyclic group or an -SO ₂ - containing cyclic group; B" is an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, an oxygen atom or a sulfur atom, and n' is an integer of 0 to 2. * represents a bond.]

In the general formulae (b5-r-1) and (b5-r-2), B" represents an alkylene group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, an oxygen atom, or a sulfur atom.
B" is preferably an alkylene group having 1 to 5 carbon atoms or --O--, more preferably an alkylene group having 1 to 5 carbon atoms, and even more preferably a methylene group.

In the general formulae (b5-r-1) to (b5-r-4), ^Rb'51 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, -COOR", -OC(=O)R", a hydroxyalkyl group or a cyano group, and among these, it is preferable that they each independently represent a hydrogen atom or a cyano group.

Specific examples of groups represented by general formulas (b5-r-1) to (b5-r-4) are listed below. "Ac" in the formulas represents an acetyl group.

Examples of the substituent in the cyclic group of R ¹⁰¹ include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, and a nitro group.
The alkyl group as the substituent is preferably an alkyl group having 1 to 5 carbon atoms.
The alkoxy group as a substituent is preferably an alkoxy group having 1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, or a tert-butoxy group, and most preferably a methoxy group or an ethoxy group.
As the halogen atom as a substituent, a fluorine atom, a bromine atom or an iodine atom is preferred.
Examples of the halogenated alkyl group as a substituent include alkyl groups having 1 to 5 carbon atoms, such as methyl, ethyl, propyl, n-butyl, and tert-butyl groups, in which some or all of the hydrogen atoms have been substituted with the above-mentioned halogen atoms.
The carbonyl group as a substituent is a group that substitutes a methylene group (-CH ₂ -) that constitutes a cyclic hydrocarbon group.

The cyclic hydrocarbon group in R ¹⁰¹ may be a fused ring group containing a fused ring in which an aliphatic hydrocarbon ring and an aromatic ring are fused. Examples of the fused ring include a polycycloalkane having a polycyclic skeleton of a bridged ring system to which one or more aromatic rings are fused. Specific examples of the bridged ring polycycloalkane include bicycloalkanes such as bicyclo[2.2.1]heptane (norbornane) and bicyclo[2.2.2]octane. The fused ring group is preferably a group containing a fused ring in which two or three aromatic rings are fused to a bicycloalkane, and more preferably a group containing a fused ring in which two or three aromatic rings are fused to a bicyclo[2.2.2]octane. Specific examples of the fused ring group in R ¹⁰¹ include those represented by the following formulae (r-br-1) to (r-br-2). In the formulae, * represents a bond bonded to Y ¹⁰¹ in formula (b-1).

Examples of the substituent that the fused cyclic group for R ¹⁰¹ may have include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, a nitro group, an aromatic hydrocarbon group, and an alicyclic hydrocarbon group.
Examples of the alkyl group, alkoxy group, halogen atom and halogenated alkyl group as the substituent of the condensed cyclic group include the same as those exemplified as the substituent of the cyclic group in R ¹⁰¹ above.
Examples of the aromatic hydrocarbon group as the substituent of the fused ring group include a group in which one hydrogen atom has been removed from an aromatic ring (aryl group: for example, a phenyl group, a naphthyl group, etc.), a group in which one hydrogen atom of the aromatic ring has been substituted with an alkylene group (for example, an arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, a 2-naphthylethyl group, etc.), and the heterocyclic groups represented by the above formulas (r-hr-1) to (r-hr-6), respectively.
Examples of the alicyclic hydrocarbon group as a substituent of the fused cyclic group include groups in which one hydrogen atom has been removed from a monocycloalkane, such as cyclopentane or cyclohexane; groups in which one hydrogen atom has been removed from a polycycloalkane, such as adamantane, norbornane, isobornane, tricyclodecane or tetracyclododecane; lactone-containing cyclic groups represented by each of the general formulae (a2-r-1) to (a2-r-7); —SO ₂ -containing cyclic groups represented by each of the general formulae (b5-r-1) to (b5-r-4); and heterocyclic groups represented by each of the formulae (r-hr-7) to (r-hr-16).

A chain alkyl group which may have a substituent:
The chain alkyl group for R ¹⁰¹ may be either a straight chain or a branched chain.
The linear alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and most preferably 1 to 10 carbon atoms.
The branched alkyl group preferably has 3 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and most preferably 3 to 10. Specific examples include a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, and a 4-methylpentyl group.

A chain alkenyl group which may have a substituent:
The chain alkenyl group for R ¹⁰¹ may be either linear or branched, and preferably has 2 to 10 carbon atoms, more preferably 2 to 5, even more preferably 2 to 4, and particularly preferably 3. Examples of linear alkenyl groups include vinyl groups, propenyl groups (allyl groups), and butenyl groups. Examples of branched alkenyl groups include 1-methylvinyl groups, 2-methylvinyl groups, 1-methylpropenyl groups, and 2-methylpropenyl groups.
Of the above chain alkenyl groups, linear alkenyl groups are preferred, vinyl groups and propenyl groups are more preferred, and vinyl groups are particularly preferred.

Examples of the substituent in the chain alkyl or alkenyl group of R ¹⁰¹ include an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, a nitro group, an amino group, and the cyclic groups in R ¹⁰¹ above.

In formula (b-1), Y ¹⁰¹ is a single bond or a divalent linking group containing an oxygen atom.
When Y ¹⁰¹ is a divalent linking group containing an oxygen atom, Y ¹⁰¹ may contain an atom other than an oxygen atom. Examples of the atom other than an oxygen atom include a carbon atom, a hydrogen atom, a sulfur atom, and a nitrogen atom.
Examples of the divalent linking group containing an oxygen atom include linking groups represented by the following general formulae (y-al-1) to (y-al-7), respectively. In the following general formulae (y-al-1) to (y-al-7), what is bonded to R ¹⁰¹ in the above formula (b-1) is V' ¹⁰¹ in the following general formulae (y-al-1) to (y-al-7).

[In the formula, V' ¹⁰¹ is a single bond or an alkylene group having 1 to 5 carbon atoms, and V' ¹⁰² is a divalent saturated hydrocarbon group having 1 to 30 carbon atoms.]

The divalent saturated hydrocarbon group for V' ¹⁰² is preferably an alkylene group having 1 to 30 carbon atoms, more preferably an alkylene group having 1 to 10 carbon atoms, and even more preferably an alkylene group having 1 to 5 carbon atoms.

The alkylene group in ^V'101 and ^V'102 may be a linear alkylene group or a branched alkylene group, with a linear alkylene group being preferred.
Specific examples of the alkylene group in V' ¹⁰¹ and V' ¹⁰² include a methylene group [-CH ₂ -]; alkylmethylene groups such as -CH(CH ₃ )-, -CH(CH ₂ CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CH ₃ )(CH ₂ CH ₃ )-, -C(CH ₃ )(CH ₂ CH ₂ CH ₃ )-, and -C(CH ₂ CH ₃ ) ₂ -; an ethylene group [-CH ₂ CH ₂ -]; alkylethylene groups such as -CH(CH ₃ )CH ₂ -, -CH(CH ₃ )CH(CH ₃ )-, -C(CH ₃ ) ₂ CH ₂ -, and -CH(CH ₂ CH ₃ )CH ₂ -; a trimethylene group (n-propylene group) [-CH ₂ CH ₂ CH _2- ] _; alkyl trimethylene groups such as -CH( _CH3 ) _CH2CH2- _and _-CH2CH ₍ _CH3 ₎ _CH2- _; tetramethylene group _[ _{-CH2CH2CH2CH2-} ]; _alkyl tetramethylene groups such as -CH ₍ CH3 ₎ _CH2CH2CH2- _and _-CH2CH ₍ _CH3 ₎ _CH2CH2- ; pentamethylene group [ _{-CH2CH2CH2CH2CH2CH2-} ].
In addition, some of the methylene groups in the alkylene group in ^V'101 or ^V'102 may be substituted with a divalent aliphatic cyclic group having 5 to 10 carbon atoms. The aliphatic cyclic group is preferably a divalent group obtained by further removing one hydrogen atom from the cyclic aliphatic hydrocarbon group (monocyclic aliphatic hydrocarbon group, polycyclic aliphatic hydrocarbon group) of ^Ra'3 in formula (a1-r-1), and more preferably a cyclohexylene group, a 1,5-adamantylene group or a 2,6-adamantylene group.

In formula (b-1), V ¹⁰¹ is a single bond, an alkylene group or a fluorinated alkylene group. Of these, V ¹⁰¹ is preferably a single bond or a linear fluorinated alkylene group having 1 to 4 carbon atoms.

In formula (b-1), R ¹⁰² is a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms. R ¹⁰² is preferably a fluorine atom or a perfluoroalkyl group having 1 to 5 carbon atoms, and more preferably a fluorine atom.

Specific examples of the anion moiety represented by formula (b-1) include, for example, when Y ¹⁰¹ is a single bond, fluorinated alkylsulfonate anions such as trifluoromethanesulfonate anion and perfluorobutanesulfonate anion; and, when Y ¹⁰¹ is a divalent linking group containing an oxygen atom, anions represented by any of the following formulas (an-1) to (an-3) are included.

[In the formula, R" ¹⁰¹ is an aliphatic cyclic group which may have a substituent, a monovalent heterocyclic group represented by each of the above chemical formulas (r-hr-1) to (r-hr-6), a fused cyclic group represented by the above formula (r-br-1) or (r-br-2), a chain-like alkyl group which may have a substituent, or an aromatic cyclic group which may have a substituent. R" ¹⁰² is an aliphatic cyclic group which may have a substituent, a fused cyclic group represented by the above formula (r-br-1) or (r-br-2), a lactone-containing cyclic group represented by each of the above general formulas (a2-r-1), (a2-r-3) to (a2-r-7), or an -SO ₂ - containing cyclic group represented by each of the above general formulas (b5-r-1) to (b5-r-4). R" ¹⁰³ is an aromatic cyclic group which may have a substituent, an aliphatic cyclic group which may have a substituent, or a chain-like alkenyl group which may have a substituent. V" ¹⁰¹ is a single bond, an alkylene group having 1 to 4 carbon atoms, or a fluorinated alkylene group having 1 to 4 carbon atoms. R ¹⁰² is a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms. Each v" is independently an integer of 0 to 3, each q" is independently an integer of 0 to 20, and n" is 0 or 1.

The aliphatic cyclic groups which may have a substituent of R" ¹⁰¹ , R" ¹⁰² and R" ¹⁰³ are preferably the groups exemplified as the cyclic aliphatic hydrocarbon group in R ¹⁰¹ in formula (b-1) above. Examples of the substituent include the same as the substituents which may substitute the cyclic aliphatic hydrocarbon group in R ¹⁰¹ in formula (b-1) above.

The aromatic cyclic group which may have a substituent in R" ¹⁰¹ and R" ¹⁰³ is preferably a group exemplified as the aromatic hydrocarbon group in the cyclic hydrocarbon group in ^R101 in the above formula (b-1). Examples of the substituent include the same as the substituent which may substitute the aromatic hydrocarbon group in ^R101 in the above formula (b-1).

The chain alkyl group which may have a substituent in R″ ¹⁰¹ is preferably a group exemplified as the chain alkyl group in R ¹⁰¹ in the above formula (b-1).
The chain alkenyl group which may have a substituent in R″ ¹⁰³ is preferably a group exemplified as the chain alkenyl group in R ¹⁰¹ in the above formula (b-1).

Anion in Component (b-2) In formula (b-2), R ¹⁰⁴ and R ¹⁰⁵ each independently represent a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a chain-like alkenyl group which may have a substituent, and examples of these include the same as R ¹⁰¹ in formula (b-1). However, R ¹⁰⁴ and R ¹⁰⁵ may be bonded to each other to form a ring.
R ¹⁰⁴ and R ¹⁰⁵ are preferably a chain alkyl group which may have a substituent, and more preferably a linear or branched alkyl group, or a linear or branched fluorinated alkyl group.
The number of carbon atoms in the chain-like alkyl group is preferably 1 to 10, more preferably 1 to 7, and even more preferably 1 to 3. The number of carbon atoms in the chain-like alkyl group of R ¹⁰⁴ and R ¹⁰⁵ is preferably as small as possible within the above range of the number of carbon atoms, for reasons such as good solubility in a resist solvent. In addition, in the chain-like alkyl group of R ¹⁰⁴ and R ¹⁰⁵ , the more hydrogen atoms substituted with fluorine atoms, the stronger the acid strength becomes, and the more the transparency to high-energy light and electron beams of 250 nm or less is improved, which is preferable. The ratio of fluorine atoms in the chain-like alkyl group, i.e., the fluorination rate, is preferably 70 to 100%, more preferably 90 to 100%, and most preferably a perfluoroalkyl group in which all hydrogen atoms are substituted with fluorine atoms.
In formula (b-2), V ¹⁰² and V ¹⁰³ each independently represent a single bond, an alkylene group, or a fluorinated alkylene group, and examples of V ¹⁰¹ in formula (b-1) include the same as those described above.
In formula (b-2), L ¹⁰¹ and L ¹⁰² each independently represent a single bond or an oxygen atom.

Anion in Component (b-3) In formula (b- ³ ), R to R each independently represent a cyclic group which may have a substituent, ^a chain-like alkyl group which may have a substituent, or a chain-like alkenyl group which may have a substituent, and examples of these include the same as R ¹⁰¹ in formula (b-1).
In formula (b-3), L ¹⁰³ to L ¹⁰⁵ each independently represent a single bond, —CO— or —SO ₂ —.

Among the above, the anion in component (b-1) is preferred as the anion portion of component (B).

{Cation part}
In the above formulae (b-1), (b-2) and (b-3), ^M'm+ represents an m-valent onium cation, of which sulfonium cation and iodonium cation are preferred.
m is an integer of 1 or more.

Preferred cationic moieties ((M'm ⁺ ) _1/m ) include organic cations represented by the following general formulas (ca-1) to (ca-3).

[In the formula, R ²⁰¹ to R ²⁰⁷ each independently represent an aryl group, an alkyl group or an alkenyl group which may have a substituent. R ²⁰¹ to R ²⁰³ and R ²⁰⁶ to R ²⁰⁷ may be bonded to each other to form a ring together with the sulfur atom in the formula. R ²⁰⁸ to R ²⁰⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ²¹⁰ is an aryl group which may have a substituent, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, or an -SO ₂ - containing cyclic group which may have a substituent. L ²⁰¹ represents -C(=O)- or -C(=O)-O-.]

In the above general formulae (ca-1) to (ca-3), the aryl group for R ²⁰¹ to R ²⁰⁷ can be an unsubstituted aryl group having 6 to 20 carbon atoms, and a phenyl group or a naphthyl group is preferable.
The alkyl group for R ²⁰¹ to R ²⁰⁷ is preferably a chain or cyclic alkyl group having 1 to 30 carbon atoms.
The alkenyl group for R ²⁰¹ to R ²⁰⁷ preferably has 2 to 10 carbon atoms.
Examples of the substituent that R ²⁰¹ to R ²⁰⁷ and R ²¹⁰ may have include an alkyl group, a halogen atom, a halogenated alkyl group, a carbonyl group, a cyano group, an amino group, an aryl group, and groups represented by the following general formulas (ca-r-1) to (ca-r-7), respectively.

[In the formula, ^R'201 each independently represents a hydrogen atom, a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a chain-like alkenyl group which may have a substituent.]

Optionally substituted cyclic group:
The cyclic group is preferably a cyclic hydrocarbon group, and the cyclic hydrocarbon group may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group. The aliphatic hydrocarbon group means a hydrocarbon group that does not have aromaticity. The aliphatic hydrocarbon group may be saturated or unsaturated, and is usually preferably saturated.

The aromatic hydrocarbon group in ^R'201 is a hydrocarbon group having an aromatic ring. The aromatic hydrocarbon group preferably has 3 to 30 carbon atoms, more preferably 5 to 30 carbon atoms, even more preferably 5 to 20 carbon atoms, particularly preferably 6 to 15 carbon atoms, and most preferably 6 to 10 carbon atoms. However, this number of carbon atoms does not include the number of carbon atoms in the substituent.
Specific examples of the aromatic ring contained in the aromatic hydrocarbon group in ^R'201 include benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, and aromatic heterocycles in which some of the carbon atoms constituting these aromatic rings are substituted with heteroatoms. Examples of the heteroatom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom.
Specific examples of the aromatic hydrocarbon group for ^R'201 include a group in which one hydrogen atom has been removed from the aromatic ring (aryl group: for example, a phenyl group, a naphthyl group, etc.), a group in which one hydrogen atom of the aromatic ring has been substituted with an alkylene group (for example, an arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, a 2-naphthylethyl group, etc.). The alkylene group (the alkyl chain in the arylalkyl group) preferably has 1 to 4 carbon atoms, more preferably 1 to 2 carbon atoms, and particularly preferably 1 carbon atom.

The cyclic aliphatic hydrocarbon group for ^R'201 includes an aliphatic hydrocarbon group containing a ring in the structure.
Examples of the aliphatic hydrocarbon group containing a ring in its structure include alicyclic hydrocarbon groups (groups in which one hydrogen atom has been removed from an aliphatic hydrocarbon ring), groups in which an alicyclic hydrocarbon group is bonded to the end of a straight-chain or branched-chain aliphatic hydrocarbon group, and groups in which an alicyclic hydrocarbon group is present in the middle of a straight-chain or branched-chain aliphatic hydrocarbon group.
The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably has 3 to 12 carbon atoms.
The alicyclic hydrocarbon group may be a polycyclic group or a monocyclic group. The monocyclic alicyclic hydrocarbon group is preferably a group obtained by removing one or more hydrogen atoms from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane. The polycyclic alicyclic hydrocarbon group is preferably a group obtained by removing one or more hydrogen atoms from a polycycloalkane, and the polycycloalkane preferably has 7 to 30 carbon atoms. Among them, the polycycloalkane is more preferably a polycycloalkane having a polycyclic skeleton of a bridged ring system such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane; or a polycycloalkane having a polycyclic skeleton of a condensed ring system such as a cyclic group having a steroid skeleton.

Among these, the cyclic aliphatic hydrocarbon group for ^R'201 is preferably a group in which one or more hydrogen atoms have been removed from a monocycloalkane or polycycloalkane, more preferably a group in which one hydrogen atom has been removed from a polycycloalkane, particularly preferably an adamantyl group or a norbornyl group, and most preferably an adamantyl group.

The linear or branched aliphatic hydrocarbon group which may be bonded to the alicyclic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, and particularly preferably 1 to 3 carbon atoms.
As the straight-chain aliphatic hydrocarbon group, a straight-chain alkylene group is preferable, and specific examples thereof include a methylene group [-CH ₂ -], an ethylene group [-(CH ₂ ) ₂ -], a trimethylene group [-(CH ₂ ) ₃ -], a tetramethylene group [-(CH ₂ ) ₄ -], a pentamethylene group [-(CH ₂ ) ₅ -], etc.
The branched aliphatic hydrocarbon group is preferably a branched alkylene group, and specific examples thereof _include alkylmethylene groups such as -CH( _CH3 )-, -CH( _CH2CH3 )-, -C( _CH3 ) _2- _{, -C(CH3)(CH2CH3)-, -C(CH3)(CH2CH2CH3)-, and -C(CH2CH3} ₎ _2- _; _{alkylethylene} _groups _such _as _-CH ₍ _CH3 ₎ _CH2- _, -CH( _CH3 )CH( _CH3 ) _- , -C( _CH3 ) _2CH2- _, -CH ₍ _CH2CH3 ) _CH2- _, and -C( _CH2CH3 ) ₂ _- _CH2- _; and alkyl alkylene groups such as alkyl trimethylene groups such as _-CH (CH ₃ )CH ₂ CH ₂ CH ₂ -, -CH ₂ CH(CH ₃ )CH ₂ CH ₂ -, etc. The alkyl group in the alkyl alkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

Furthermore, the cyclic hydrocarbon group in ^R'201 may contain a heteroatom, such as a heterocycle. Specific examples include the lactone-containing cyclic groups represented by the general formulae (a2-r-1) to (a2-r-7) above, the -SO ₂ -containing cyclic groups represented by the general formulae (b5-r-1) to (b5-r-4) above, and the heterocyclic groups represented by the chemical formulae (r-hr-1) to (r-hr-16) above.

Examples of the substituent in the cyclic group of ^R'201 include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, and a nitro group.
The alkyl group as the substituent is preferably an alkyl group having 1 to 5 carbon atoms, and most preferably a methyl group, an ethyl group, a propyl group, an n-butyl group or a tert-butyl group.
The alkoxy group as a substituent is preferably an alkoxy group having 1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, or a tert-butoxy group, and most preferably a methoxy group or an ethoxy group.
As the halogen atom as a substituent, a fluorine atom is preferred.
Examples of the halogenated alkyl group as a substituent include alkyl groups having 1 to 5 carbon atoms, such as methyl, ethyl, propyl, n-butyl, and tert-butyl groups, in which some or all of the hydrogen atoms have been substituted with the above-mentioned halogen atoms.
The carbonyl group as a substituent is a group that substitutes a methylene group (-CH ₂ -) that constitutes a cyclic hydrocarbon group.

A chain alkyl group which may have a substituent:
The chain alkyl group of ^R'201 may be either linear or branched.
The linear alkyl group preferably has 1 to 20 carbon atoms, more preferably has 1 to 15 carbon atoms, and most preferably has 1 to 10 carbon atoms.
The branched alkyl group preferably has 3 to 20 carbon atoms, more preferably has 3 to 15 carbon atoms, and most preferably has 3 to 10 carbon atoms. Specific examples include a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, and a 4-methylpentyl group.

A chain alkenyl group which may have a substituent:
The chain alkenyl group of ^R'201 may be either linear or branched, and preferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms, further preferably 2 to 4 carbon atoms, and particularly preferably 3 carbon atoms. Examples of linear alkenyl groups include vinyl groups, propenyl groups (allyl groups), and butenyl groups. Examples of branched alkenyl groups include 1-methylvinyl groups, 2-methylvinyl groups, 1-methylpropenyl groups, and 2-methylpropenyl groups.
Of the above chain alkenyl groups, linear alkenyl groups are preferred, vinyl groups and propenyl groups are more preferred, and vinyl groups are particularly preferred.

Examples of the substituent in the chain alkyl or alkenyl group of ^R'201 include an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, a nitro group, an amino group, and the cyclic groups in ^R'201 described above.

The optionally substituted cyclic group, optionally substituted chain alkyl group, or optionally substituted chain alkenyl group for ^R'201 is as described above, and examples of the optionally substituted cyclic group or optionally substituted chain alkyl group include the same as the acid dissociable group represented by formula (a1-r-2) above.

Among these, ^R'201 is preferably a cyclic group which may have a substituent, and more preferably a cyclic hydrocarbon group which may have a substituent. More specifically, for example, a phenyl group, a naphthyl group, a group in which one or more hydrogen atoms have been removed from a polycycloalkane, a lactone-containing cyclic group represented by each of the general formulae (a2-r-1) to (a2-r-7), an -SO ₂ --containing cyclic group represented by each of the general formulae (b5-r-1) to (b5-r-4), etc. are preferred.

In the above general formulae (ca-1) to (ca-3), when R ²⁰¹ to R ²⁰³ and R ²⁰⁶ to R ²⁰⁷ are bonded to each other to form a ring together with the sulfur atom in the formula, they may be bonded via a heteroatom such as a sulfur atom, an oxygen atom or a nitrogen atom, or a functional group such as a carbonyl group, -SO-, -SO ₂ -, -SO ₃ -, -COO-, -CONH- or -N(R _N )- (wherein R _N is an alkyl group having 1 to 5 carbon atoms). As for the ring formed, one ring containing the sulfur atom in the ring skeleton in the formula is preferably a 3- to 10-membered ring including the sulfur atom, and particularly preferably a 5- to 7-membered ring. Specific examples of the ring formed include a thiophene ring, a thiazole ring, a benzothiophene ring, a dibenzothiophene ring, a 9H-thioxanthene ring, a thioxanthone ring, a thianthrene ring, a phenoxathiin ring, a tetrahydrothiophenium ring, and a tetrahydrothiopyranium ring.

R ²⁰⁸ to R ²⁰⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and when they represent an alkyl group, they may be bonded to each other to form a ring.

R ²¹⁰ is an aryl group which may have a substituent, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, or an --SO ₂ -- containing cyclic group which may have a substituent.
The aryl group for R ²¹⁰ includes unsubstituted aryl groups having 6 to 20 carbon atoms, and is preferably a phenyl group or a naphthyl group.
The alkyl group for R ²¹⁰ is preferably a chain or cyclic alkyl group having 1 to 30 carbon atoms.
The alkenyl group for R ²¹⁰ preferably has 2 to 10 carbon atoms.
As the -SO ₂ -containing cyclic group for R ²¹⁰ which may have a substituent, a "-SO ₂ -containing polycyclic group" is preferable, and a group represented by the above general formula (b5-r-1) is more preferable.

Specific examples of the cations represented by formula (ca-1) are shown below.

Specific examples of suitable cations represented by the formula (ca-1) include the cations represented by the following chemical formulas.

[In the formula, g1, g2, and g3 each represent a repeating number, where g1 is an integer of 1 to 5, g2 is an integer of 0 to 20, and g3 is an integer of 0 to 20.]

[In the formula, R″ ²⁰¹ is a hydrogen atom or a substituent, and the substituent is the same as those exemplified as the substituent that R ²⁰¹ to R ²⁰⁷ and R ²¹⁰ to R ²¹² may have.]

Specific examples of suitable cations represented by the formula (ca-2) include diphenyliodonium cation, bis(4-tert-butylphenyl)iodonium cation, etc.

Specific examples of suitable cations represented by the formula (ca-3) include the cations represented by the following formulas (ca-3-1) to (ca-3-6).

In the resist composition of this embodiment, the component (B) may use either a single type, or a combination of two or more types.
When the resist composition contains the component (B), the amount of the component (B) in the resist composition is preferably less than 50 parts by mass, and more preferably 10 to 40 parts by mass, per 100 parts by mass of the component (A).
By setting the content of the component (B) within the above-mentioned preferred range, sufficient pattern formation can be achieved. Furthermore, when the components of the resist composition are dissolved in an organic solvent, a homogeneous solution is easily obtained, and the storage stability of the resist composition is also favorable.

<<Base component (D)>>
The resist composition of this embodiment may further contain, in addition to the component (A), a base component (component (D)) that traps acid generated upon exposure (i.e., controls the diffusion of acid). The component (D) acts as a quencher (acid diffusion controller) that traps acid generated in the resist composition upon exposure.
Examples of the component (D) include a photodegradable base (D1) (hereinafter referred to as "component (D1)") that decomposes upon exposure to light and loses its acid diffusion controllability, and a nitrogen-containing organic compound (D2) (hereinafter referred to as "component (D2)") that does not fall under the category of component (D1). Among these, the photodegradable base (component (D1)) is preferred because it is likely to enhance all of the properties of increasing sensitivity, reducing roughness, and suppressing the occurrence of coating defects.

- Component (D1) By using a resist composition that contains the component (D1), the contrast between exposed and unexposed areas of the resist film can be further improved when forming a resist pattern.
The component (D1) is not particularly limited as long as it decomposes upon exposure to light and loses its acid diffusion controllability, and is preferably one or more compounds selected from the group consisting of a compound represented by the following general formula (d1-1) (hereinafter referred to as "component (d1-1)"), a compound represented by the following general formula (d1-2) (hereinafter referred to as "component (d1-2)"), and a compound represented by the following general formula (d1-3) (hereinafter referred to as "component (d1-3)"):
The components (d1-1) to (d1-3) do not act as quenchers in the exposed areas of the resist film because they decompose and lose their acid diffusion control ability (basicity), but act as quenchers in the unexposed areas of the resist film.

[In the formula, Rd ¹ to Rd ⁴ are a cyclic group which may have a substituent, a chain alkyl group which may have a substituent, or a chain alkenyl group which may have a substituent. However, in Rd ² in formula (d1-2), a fluorine atom is not bonded to the carbon atom adjacent to the S atom. Yd ¹ is a single bond or a divalent linking group. m is an integer of 1 or more, and each M ^m+ is independently an m-valent organic cation.]

{(d1-1) component}
In formula (d1-1), Rd ¹ represents a cyclic group which may have a substituent, a chain alkyl group which may have a substituent, or a chain alkenyl group which may have a substituent, and examples of these groups include the same as those for R' ²⁰¹ described above.
Among these, Rd ¹ is preferably an aromatic hydrocarbon group which may have a substituent, an aliphatic cyclic group which may have a substituent, or a chain-like alkyl group which may have a substituent. Examples of the substituent which these groups may have include a hydroxyl group, an oxo group, an alkyl group, an aryl group, a fluorine atom, a fluorinated alkyl group, a lactone-containing cyclic group represented by each of the above general formulas (a2-r-1) to (a2-r-7), an ether bond, an ester bond, or a combination thereof. When an ether bond or an ester bond is contained as a substituent, it may be via an alkylene group, and in this case, the substituent is preferably a linking group represented by each of the above formulas (y-al-1) to (y-al-5). When the aromatic hydrocarbon group, aliphatic cyclic group, or chain alkyl group in Rd ¹ has a linking group represented by each of the general formulae (y-al-1) to (y-al-7) as a substituent, in the above general formulae (y-al-1) to (y-al-7), V' 101 in the above general formulae (y-al-1) to (y-al-7) bonds to a carbon atom constituting the aromatic hydrocarbon group, aliphatic cyclic group, or chain alkyl group in ^Rd ¹ in formula (d3-1).
Suitable examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, and a polycyclic structure containing a bicyclooctane skeleton (a polycyclic structure consisting of a bicyclooctane skeleton and another ring structure).
The aliphatic cyclic group is more preferably a group in which one or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane.
The chain alkyl group preferably has 1 to 10 carbon atoms. Specific examples of the chain alkyl group include linear alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group; and branched alkyl groups such as a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, and a 4-methylpentyl group.

When the chain-like alkyl group is a fluorinated alkyl group having a fluorine atom or a fluorinated alkyl group as a substituent, the number of carbon atoms in the fluorinated alkyl group is preferably 1 to 11, more preferably 1 to 8, and even more preferably 1 to 4. The fluorinated alkyl group may contain atoms other than fluorine atoms. Examples of atoms other than fluorine atoms include oxygen atoms, sulfur atoms, and nitrogen atoms.

The following are preferred examples of the anion portion of component (d1-1):

In formula (d1-1), M ^m+ represents an m-valent organic cation.
Suitable examples of the organic cation of M ^m+ include the same cations as those represented by the general formulas (ca-1) to (ca-5), respectively, more preferably the cation represented by the general formula (ca-1), and even more preferably the cations represented by the general formulas (ca-1-1) to (ca-1-70).
The component (d1-1) may be used alone or in combination of two or more.

{(d1-2) component}
In formula (d1-2), ^Rd2 represents a cyclic group which may have a substituent, a chain alkyl group which may have a substituent, or a chain alkenyl group which may have a substituent, and examples of R'201 include the same as those described above for ^R'201 .
However, in ^Rd2 , the carbon atom adjacent to the S atom does not have a fluorine atom bonded thereto (is not substituted with fluorine), whereby the anion of the component (d1-2) becomes an appropriately weak acid anion, and the quenching ability of the component (D) is improved.
^Rd2 is preferably a chain alkyl group which may have a substituent, or an aliphatic cyclic group which may have a substituent. The chain alkyl group preferably has 1 to 10 carbon atoms, and more preferably has 3 to 10 carbon atoms. The aliphatic cyclic group is more preferably a group (which may have a substituent) in which one or more hydrogen atoms have been removed from adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane, or the like; or a group in which one or more hydrogen atoms have been removed from camphor, or the like.
The hydrocarbon group of ^Rd2 may have a substituent, and examples of the substituent include the same as the substituents that may be possessed by the hydrocarbon group (aromatic hydrocarbon group, aliphatic cyclic group, chain alkyl group) in ^Rd1 of the above formula (d1-1).

The following are preferred examples of the anion portion of component (d1-2):

Cation Moiety In formula (d1-2), M ^m+ represents an m-valent organic cation and is the same as M ^m+ in formula (d1-1).
The component (d1-2) may be used alone or in combination of two or more.

{(d1-3) component}
In formula (d1-3), Rd ³ is a cyclic group which may have a substituent, a chain alkyl group which may have a substituent, or a chain alkenyl group which may have a substituent, and examples thereof include the same as those of R' ²⁰¹ , and is preferably a cyclic group, chain alkyl group, or chain alkenyl group containing a fluorine atom. Among these, a fluorinated alkyl group is preferable, and the same as the fluorinated alkyl group of Rd ¹ is more preferable.

In formula (d1-3), ^Rd4 represents a cyclic group which may have a substituent, a chain alkyl group which may have a substituent, or a chain alkenyl group which may have a substituent, and examples of ^R'201 include the same as those described above.
Among these, an alkyl group, an alkoxy group, an alkenyl group, or a cyclic group, which may have a substituent, is preferable.
The alkyl group in Rd ⁴ is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, etc. A portion of the hydrogen atoms of the alkyl group in Rd ⁴ may be substituted with a hydroxyl group, a cyano group, etc.
The alkoxy group in Rd ⁴ is preferably an alkoxy group having 1 to 5 carbon atoms, and specific examples of the alkoxy group having 1 to 5 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, and a tert-butoxy group. Of these, a methoxy group and an ethoxy group are preferred.

The alkenyl group in ^Rd4 may be the same as the alkenyl group in ^R'201 , and preferably a vinyl group, a propenyl group (allyl group), a 1-methylpropenyl group, or a 2-methylpropenyl group. These groups may further have an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms as a substituent.

The cyclic group in Rd ⁴ may be the same as the cyclic group in R' ²⁰¹ , and is preferably an alicyclic group obtained by removing one or more hydrogen atoms from a cycloalkane such as cyclopentane, cyclohexane, adamantane, norbornane, isobornane, tricyclo[5.2.1.0 ^2,6 ]decane, or tetracyclododecane, or an aromatic group such as a phenyl group or naphthyl group. When Rd ⁴ is an alicyclic group, the resist composition dissolves well in an organic solvent, resulting in good lithography properties. In addition, when Rd ⁴ is an aromatic group, in lithography using EUV or the like as an exposure light source, the resist composition has excellent light absorption efficiency, and the sensitivity and lithography properties are good.

In formula (d1-3), ^Yd1 represents a single bond or a divalent linking group.
The divalent linking group in Yd ¹ is not particularly limited, and examples thereof include a divalent hydrocarbon group which may have a substituent (an aliphatic hydrocarbon group, an aromatic hydrocarbon group), a divalent linking group containing a hetero atom, etc. These include the same as the divalent hydrocarbon group which may have a substituent and the divalent linking group containing a hetero atom mentioned in the description of the divalent linking group in Ya ²¹ in the above formula (a2-1).
^Yd1 is preferably a carbonyl group, an ester bond, an amide bond, an alkylene group, or a combination thereof. The alkylene group is more preferably a linear or branched alkylene group, and further preferably a methylene group or an ethylene group.

The following are preferred examples of the anion portion of component (d1-3):

Cation Moiety In formula (d1-3), M ^m+ represents an m-valent organic cation and is the same as M ^m+ in formula (d1-1).
The component (d1-3) may be used alone or in combination of two or more.

The component (D1) may be any one of the above components (d1-1) to (d1-3), or a combination of two or more of them.
When the resist composition contains the component (D1), the amount of the component (D1) in the resist composition is preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, and even more preferably 2 to 8 parts by mass, relative to 100 parts by mass of the component (A1).
When the amount of the component (D1) is at least as large as the preferred lower limit, particularly good lithography properties and resist pattern shape are likely to be obtained, while when the amount is no more than the upper limit, good sensitivity can be maintained and excellent throughput is also achieved.

Production method of component (D1):
The method for producing the components (d1-1) and (d1-2) is not particularly limited, and they can be produced by known methods.
The method for producing the component (d1-3) is not particularly limited, and it can be produced, for example, in the same manner as the method described in US 2012-0149916.

Regarding Component (D2) The component (D) may contain a nitrogen-containing organic compound component (hereinafter referred to as “component (D2)”) that does not fall under the category of the above-mentioned component (D1).
The component (D2) is not particularly limited as long as it acts as an acid diffusion controller and does not fall under the category of component (D1), and any known component may be used. Among these, aliphatic amines are preferred, and among these, secondary aliphatic amines and tertiary aliphatic amines are more preferred.
Aliphatic amines are amines that have one or more aliphatic groups, preferably having 1 to 12 carbon atoms.
Examples of aliphatic amines include amines in which at least one of the hydrogen atoms of ammonia _NH3 is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms (alkylamines or alkyl alcohol amines), or cyclic amines.
Specific examples of alkylamines and alkyl alcohol amines include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, and n-decylamine; dialkylamines such as diethylamine, di-n-propylamine, di-n-heptylamine, di-n-octylamine, and dicyclohexylamine; trialkylamines such as trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decylamine, and tri-n-dodecylamine; and alkyl alcohol amines such as diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, di-n-octanolamine, and tri-n-octanolamine. Among these, trialkylamines having 6 to 30 carbon atoms are more preferred, and tri-n-pentylamine or tri-n-octylamine is particularly preferred.

Examples of cyclic amines include heterocyclic compounds containing a nitrogen atom as a heteroatom. The heterocyclic compounds may be monocyclic (aliphatic monocyclic amines) or polycyclic (aliphatic polycyclic amines).
Specific examples of the aliphatic monocyclic amine include piperidine and piperazine.
The aliphatic polycyclic amine is preferably one having 6 to 10 carbon atoms, and specific examples thereof include 1,5-diazabicyclo[4.3.0]-5-nonene, 1,8-diazabicyclo[5.4.0]-7-undecene, hexamethylenetetramine, and 1,4-diazabicyclo[2.2.2]octane.

Other aliphatic amines include tris(2-methoxymethoxyethyl)amine, tris{2-(2-methoxyethoxy)ethyl}amine, tris{2-(2-methoxyethoxymethoxy)ethyl}amine, tris{2-(1-methoxyethoxy)ethyl}amine, tris{2-(1-ethoxyethoxy)ethyl}amine, tris{2-(1-ethoxypropoxy)ethyl}amine, tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine, triethanolamine triacetate, etc., with triethanolamine triacetate being preferred.

Furthermore, an aromatic amine may be used as the component (D2).
Examples of aromatic amines include 4-dimethylaminopyridine, pyrrole, indole, pyrazole, imidazole or derivatives thereof, tribenzylamine, 2,6-diisopropylaniline, N-tert-butoxycarbonylpyrrolidine, and 2,6-di-tert-butylpyridine.

The component (D2) may be used alone or in combination of two or more types.
When the resist composition contains the component (D2), the amount of the component (D2) in the resist composition is typically within the range from 0.01 to 5 parts by mass relative to 100 parts by mass of the component (A1). By ensuring that the amount is within this range, the resist pattern shape and the storage stability over time are improved.

<At least one compound (E) selected from the group consisting of organic carboxylic acids, phosphorus oxoacids and derivatives thereof>
For the purposes of preventing deterioration of sensitivity and improving the resist pattern shape and storage stability, etc., the resist composition of this embodiment may contain, as an optional component, at least one compound (E) selected from the group consisting of organic carboxylic acids, and phosphorus oxoacids and derivatives thereof (hereafter referred to as "component (E)").
Specific examples of the organic carboxylic acid include acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, and salicylic acid, and among these, salicylic acid is preferred.
Examples of phosphorus oxoacids include phosphoric acid, phosphonic acid, and phosphinic acid, with phosphonic acid being particularly preferred.
Examples of the derivatives of phosphorus oxoacids include esters in which the hydrogen atoms of the above oxoacids are substituted with hydrocarbon groups. Examples of the hydrocarbon groups include alkyl groups having 1 to 5 carbon atoms and aryl groups having 6 to 15 carbon atoms.
Examples of the derivatives of phosphoric acid include phosphoric acid esters such as di-n-butyl phosphoric acid ester and diphenyl phosphoric acid ester.
Examples of the derivatives of phosphonic acid include phosphonic acid esters such as dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonic acid, diphenyl phosphonate, and dibenzyl phosphonate.
Derivatives of phosphinic acid include phosphinic acid esters and phenylphosphinic acid.
In the resist composition of this embodiment, the component (E) may use either a single type, or a combination of two or more types.
When the resist composition contains the component (E), the content of the component (E) is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the component (A). By ensuring that the content is within this range, the sensitivity and lithography properties, etc. are improved.

<Fluorine additive component (F)>
The resist composition of this embodiment may contain a fluorine additive component (hereafter referred to as "component (F)") as a hydrophobic resin. The component (F) is used to impart water repellency to the resist film, and when used as a resin separate from the component (A), it can improve lithography properties.
As the component (F), for example, the fluorine-containing polymeric compounds described in JP-A-2010-002870, JP-A-2010-032994, JP-A-2010-277043, JP-A-2011-13569, and JP-A-2011-128226 can be used.
More specifically, the component (F) may be a polymer having a structural unit (f1) represented by the following general formula (f1-1). The polymer is preferably a polymer (homopolymer) consisting only of the structural unit (f1) represented by the following formula (f1-1); a copolymer of the structural unit (f1) and the structural unit (a1); or a copolymer of the structural unit (f1), a structural unit derived from acrylic acid or methacrylic acid, and the structural unit (a1), and more preferably a copolymer of the structural unit (f1) and the structural unit (a1). Here, the structural unit (a1) copolymerized with the structural unit (f1) is preferably a structural unit derived from 1-ethyl-1-cyclooctyl (meth)acrylate or a structural unit derived from 1-methyl-1-adamantyl (meth)acrylate, and more preferably a structural unit derived from 1-ethyl-1-cyclooctyl (meth)acrylate.

[In the formula, R is the same as above, Rf ¹⁰² and Rf ¹⁰³ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms, and Rf ¹⁰² and Rf ¹⁰³ may be the same or different. nf ¹ is an integer of 0 to 5, and Rf ¹⁰¹ is an organic group containing a fluorine atom.]

In formula (f1-1), R bonded to the carbon atom at the α-position is the same as defined above. R is preferably a hydrogen atom or a methyl group.
In formula (f1-1), the halogen atom of Rf ¹⁰² and Rf ¹⁰³ is preferably a fluorine atom. The alkyl group having 1 to 5 carbon atoms of Rf ¹⁰² and Rf ¹⁰³ may be the same as the alkyl group having 1 to 5 carbon atoms of R, and a methyl group or an ethyl group is preferable. Specific examples of the halogenated alkyl group having 1 to 5 carbon atoms of Rf ¹⁰² and Rf ¹⁰³ include groups in which part or all of the hydrogen atoms of an alkyl group having 1 to 5 carbon atoms are substituted with halogen atoms. The halogen atom is preferably a fluorine atom. Among them, Rf ¹⁰² and Rf ¹⁰³ are preferably a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 5 carbon atoms, more preferably a hydrogen atom, a fluorine atom, a methyl group, or an ethyl group, and even more preferably a hydrogen atom.
In formula (f1-1), nf ¹ represents an integer of 0 to 5, preferably an integer of 0 to 3, and more preferably 1 or 2.

In formula (f1-1), Rf ¹⁰¹ is an organic group containing a fluorine atom, and is preferably a hydrocarbon group containing a fluorine atom.
The fluorine atom-containing hydrocarbon group may be linear, branched, or cyclic and preferably has 1 to 20 carbon atoms, more preferably has 1 to 15 carbon atoms, and particularly preferably has 1 to 10 carbon atoms.
In addition, in the hydrocarbon group containing fluorine atoms, preferably 25% or more of the hydrogen atoms in the hydrocarbon group are fluorinated, more preferably 50% or more, and particularly preferably 60% or more are fluorinated, as this enhances the hydrophobicity of the resist film during immersion exposure.
Of these, Rf ¹⁰¹ is more preferably a fluorinated hydrocarbon group having 1 to 6 carbon atoms, with a trifluoromethyl group, -CH ₂ -CF ₃ , -CH ₂ -CF ₂ -CF ₃ , -CH(CF ₃ ) ₂ , -CH ₂ -CH ₂ -CF ₃ , and -CH ₂ -CH ₂ -CF ₂ -CF ₂ -CF ₂ -CF ₃ being particularly preferred.

The weight average molecular weight (Mw) of component (F) (based on polystyrene equivalent measured by gel permeation chromatography) is preferably 1,000 to 50,000, more preferably 5,000 to 40,000, and most preferably 10,000 to 30,000. When it is below the upper limit of this range, the compound has sufficient solubility in a resist solvent for use as a resist, and when it is above the lower limit of this range, the resist film has good water repellency.
The dispersity (Mw/Mn) of the component (F) is preferably from 1.0 to 5.0, more preferably from 1.0 to 3.0, and most preferably from 1.0 to 2.5.

In the resist composition of this embodiment, the component (F) may use either a single type, or a combination of two or more types.
When the resist composition contains the component (F), the amount of the component (F) per 100 parts by mass of the component (A) is preferably 0.5 to 10 parts by mass, and more preferably 1 to 10 parts by mass.

<Organic solvent component (S)>
The resist composition of this embodiment can be produced by dissolving the resist materials in an organic solvent component (hereafter referred to as “component (S)”).
The component (S) can be any solvent that is capable of dissolving the individual components used and forming a homogeneous solution, and any solvent can be appropriately selected from those that are conventionally known as solvents for chemically amplified resist compositions.
In the resist composition of this embodiment, the component (S) may be used alone or as a mixed solvent of two or more different types. Of these, PGMEA, PGME, γ-butyrolactone, EL, and cyclohexanone are preferred.

As the component (S), a mixed solvent of PGMEA and a polar solvent is also preferred. The blending ratio (mass ratio) may be appropriately determined taking into consideration the compatibility between PGMEA and the polar solvent, etc.
As the component (S), a mixed solvent of at least one selected from PGMEA and EL with γ-butyrolactone is also preferred. In this case, the mixing ratio of the former to the latter is preferably 70:30 to 95:5 by mass.
There are no particular limitations on the amount of the component (S) used, and it is set appropriately depending on the coating film thickness so as to provide a concentration that allows application to a substrate, etc. In general, the component (S) is used so that the solids concentration of the resist composition falls within the range of 0.1 to 20 mass %, and preferably 0.2 to 15 mass %.

The resist composition of this embodiment may further contain compatible additives, such as additional resins to improve the performance of the resist film, dissolution inhibitors, plasticizers, stabilizers, colorants, antihalation agents, dyes, etc., as desired.

In the resist composition of this embodiment, after dissolving the resist material in the component (S), impurities and the like may be removed using a polyimide porous film, a polyamideimide porous film, or the like. For example, the resist composition may be filtered using a filter made of a polyimide porous film, a filter made of a polyamideimide porous film, or a filter made of a polyimide porous film and a polyamideimide porous film. Examples of the polyimide porous film and the polyamideimide porous film include those described in JP 2016-155121 A.

The resist composition of the present embodiment described above contains a resin component (A1) that has a structural unit (a0) derived from a compound represented by general formula (a0-1).
In the structural unit (a0), an acid dissociable group represented by the general formula (a0-pg) (hereinafter also referred to as "acid dissociable group (a0-pg)") is bonded to an aromatic ring Ar. The acid dissociable group (a0-pg) forms an unsaturated double bond with the carbon atom C ² adjacent to the secondary carbon atom or tertiary carbon atom C ¹ bonded to the carbonyloxy group (C(=O)-O-) and the carbon atom C ² adjacent to the carbon atom C ^2. Therefore, the carbocation generated when the acid dissociable group (a0-pg) dissociates is more stable than the carbocation generated when an acid dissociable group that does not form an unsaturated double bond with the carbon C ² and the carbon C ³ dissociates. Therefore, the structural unit (a0) has improved acid dissociability.
Furthermore, in the structural unit (a0), the carboxylic acid generated upon dissociation of the acid dissociable group (a0-pg) contains an aromatic ring Ar, and therefore has higher hydrophobicity than methacrylic acid or acrylic acid. It is therefore presumed that this makes it possible to suppress film loss, pattern collapse, and the like of the resist pattern.

(Method of forming a resist pattern)
A method for forming a resist pattern according to the second aspect of the present invention is a method comprising the steps of forming a resist film on a support using the resist composition according to the first aspect of the present invention, exposing the resist film to light, and developing the exposed resist film to form a resist pattern.
One embodiment of the resist pattern forming method is, for example, a resist pattern forming method carried out as follows.

First, the resist composition of the above-described embodiment is applied onto a support using a spinner or the like, and then baked (post-applied bake (PAB)) at a temperature of, for example, 80 to 150° C. for 40 to 120 seconds, preferably 60 to 90 seconds, to form a resist film.
Next, the resist film is selectively exposed using an exposure device such as an electron beam lithography device or an ArF lithography device, either through a mask (mask pattern) on which a predetermined pattern has been formed, or by lithography using direct irradiation with an electron beam without using a mask pattern, and then baked (post-exposure bake (PEB)) for 40 to 120 seconds, preferably 60 to 90 seconds, at a temperature of, for example, 80 to 150° C.
Next, the resist film is developed using an alkaline developer in the case of an alkaline development process, or a developer containing an organic solvent (organic developer) in the case of a solvent development process.

After the development process, a rinse process is preferably carried out. In the case of an alkaline development process, the rinse process is preferably a water rinse using pure water, and in the case of a solvent development process, a rinse liquid containing an organic solvent is preferably used.
In the case of a solvent development process, after the development treatment or rinsing treatment, a treatment may be carried out in which the developer or rinsing liquid adhering to the pattern is removed by using a supercritical fluid.
After the development treatment or rinsing treatment, drying is performed. In some cases, a baking treatment (post-baking) may be performed after the development treatment.

The support is not particularly limited, and conventionally known materials can be used, such as substrates for electronic components and substrates on which a predetermined wiring pattern is formed. More specifically, examples include silicon wafers, substrates made of metals such as copper, chromium, iron, and aluminum, and glass substrates. Materials that can be used for the wiring pattern include, for example, copper, aluminum, nickel, and gold.

The wavelength used for exposure is not particularly limited, and radiation such as ArF excimer laser, KrF excimer laser, _F2 excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-rays, and soft X-rays can be used.

The exposure method for the resist film may be a normal exposure method (dry exposure) performed in air or an inert gas such as nitrogen, or may be liquid immersion exposure (liquid immersion lithography).
Immersion exposure is an exposure method in which the space between the resist film and the lowest lens of the exposure tool is filled with a solvent (immersion medium) that has a refractive index greater than that of air, and exposure (immersion exposure) is then performed in that state.
The immersion medium is preferably a solvent having a refractive index greater than that of air and less than that of the resist film to be exposed, and examples of such a solvent include water, a fluorine-based inert liquid, a silicon-based solvent, and a hydrocarbon-based solvent.
As the liquid immersion medium, water is preferably used.

The alkaline developer used in the development treatment in the alkaline development process may be, for example, a 0.1 to 10% by weight aqueous solution of tetramethylammonium hydroxide (TMAH).
The organic solvent contained in the organic developer used in the development treatment in the solvent development process may be any organic solvent capable of dissolving the component (A) (the component (A) before exposure), and may be appropriately selected from known organic solvents. Specific examples of the organic solvent include polar solvents such as ketone solvents, ester solvents, alcohol solvents, nitrile solvents, amide solvents, and ether solvents, and hydrocarbon solvents.

Examples of ester-based solvents include methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, pentyl acetate, isopentyl acetate, amyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl-3-ethoxypropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, propyl lactate, butyl butanoate, methyl 2-hydroxyisobutyrate, isoamyl acetate, isobutyl isobutyrate, and butyl propionate.

Examples of nitrile solvents include acetonitrile, propionitrile, valeronitrile, butyronitrile, etc.

　Known additives can be added to the organic developer as necessary. Examples of such additives include surfactants.

The development process can be carried out by a known development method, such as a method of immersing the support in a developer for a certain period of time (dip method), a method of piling up the developer on the surface of the support by surface tension and leaving it still for a certain period of time (paddle method), a method of spraying the developer on the surface of the support (spray method), or a method of continuously applying developer while scanning a developer application nozzle at a constant speed onto a support rotating at a constant speed (dynamic dispense method).

The organic solvent contained in the rinse solution used in the rinsing treatment after the development treatment in the solvent development process can be appropriately selected from the organic solvents listed above as the organic solvents used in the organic developer, which do not easily dissolve the resist pattern. Usually, at least one solvent selected from the group consisting of hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents, and ether solvents is used.
These organic solvents may be used alone or in combination of two or more thereof, and may be used in combination with other organic solvents or water.

The rinse treatment (cleaning treatment) using a rinse solution can be carried out by a known rinse method. Examples of the rinse treatment method include a method in which the rinse solution is continuously applied onto a support rotating at a constant speed (spin coating method), a method in which the support is immersed in the rinse solution for a certain period of time (dip method), and a method in which the rinse solution is sprayed onto the surface of the support (spray method).

The resist composition of the above-mentioned embodiment and the various materials used in the method of forming a resist pattern of the above-mentioned embodiment (e.g., a resist solvent, a developer, a rinse solution, a composition for forming an antireflective film, a composition for forming a top coat, etc.) preferably do not contain impurities such as metals, metal salts containing halogens, acids, alkalis, and components containing sulfur atoms or phosphorus atoms.
Here, examples of impurities containing metal atoms include Na, K, Ca, Fe, Cu, Mn, Mg, Al, Cr, Ni, Zn, Ag, Sn, Pb, Li, or salts thereof. The content of impurities contained in these materials is preferably 200 ppb or less, more preferably 1 ppb or less, even more preferably 100 ppt (parts per trillion) or less, particularly preferably 10 ppt or less, and most preferably substantially free of impurities (below the detection limit of the measuring device).

The resist pattern forming method of this embodiment described above uses the resist composition described above, which allows for high sensitivity and the formation of a resist pattern with good resolution.

(Compound)
The compound of this embodiment is represented by the following general formula (a0-1).

The compound of this embodiment is the same as the compound that derives the structural unit (a0) that is contained in the component (A1) of the resist composition related to the first aspect.
The compound of this embodiment is preferably at least one selected from the group consisting of compounds represented by the general formula (a0-t1) and compounds represented by the general formula (a0-s1).

(Method of producing the compound)
The method for producing the compound of the present embodiment is not particularly limited, and the compound can be produced by appropriately combining known methods.

The compound of this embodiment is useful for producing a polymeric compound having the structural unit (a0) (resin component (A1) in the first embodiment).

<Polymer Compound>
The polymer compound of this embodiment has a structural unit (a0) derived from a compound represented by formula (a0-1). That is, the polymer compound of this embodiment is the same as the resin component (A1) in the first aspect.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

<Synthesis of Compounds>
[Synthesis Example 1: Synthesis of Monomer (m01)]
5.9 g of styrene carboxylic acid was dissolved in 40.0 g of tetrahydrofuran, and a mixed solution of 7.6 g of diazabicycloundenose (DBU), 5.8 g of 3-methylcyclohexenol, 9.0 g of carbonyldiimidazole (CDI), and 40.0 g of tetrahydrofuran was added dropwise to the solution under ice cooling. After stirring at 60°C for 4 hours, the solvent was distilled off, 80.0 g of heptane was added to the residue, and impurities were removed by filtration. Then, the mixture was purified by column chromatography to obtain a monomer (m01).

^{The 1} H NMR measurement results of the monomer (m01) are shown below.
^1H NMR (400MHz, DMSO-d6) δ (ppm) = 1.63 (4H, m), 1.93 (2H, m), 2.19 (2H, m), 5.13 (1H, q), 5.25 (1H, dd), 5.37 (1H, m), 5.76 (1H, dd), 6.72 (1H, dd), 7.45 (2H, d), 7.67 (2H, d)

[Synthesis Examples 2 to 10: Synthesis of Monomers (m02) to (m06)]
Monomers (m02) to (m06) were obtained in the same manner as in the above "Synthesis Example 1: Synthesis of Monomer (m01)" except that the combination of starting materials was changed.

^{The 1} H NMR measurement results of the monomer (m02) are shown below.
^1H NMR (400MHz, DMSO-d6) δ (ppm) = 1.50 (2H,m), 1.73 (5H,m), 2.09 (4H,m), 5.20 (1H,m), 5.25 (1H,m), 5.29 (1H,m), 5.76 (1H,dd), 6.72 (1H,dd), 7.45 (2H,d), 7.67 (2H,d)

^{The 1} H NMR measurement results of the monomer (m03) are shown below.
^1H NMR (400MHz, DMSO-d6) δ (ppm) = 1.63 (4H, m), 1.93 (2H, m), 2.19 (2H, m), 5.13 (1H, q), 5.25 (1H, dd), 5.37 (1H, m), 5.76 (1H, dd), 6.72 (1H, dd), 7.37 (2H, m), 7.84 (2H, m)

^{The 1} H NMR measurement results of the monomer (m04) are shown below.
^1H NMR (400MHz, DMSO-d6) δ (ppm) = 1.70 (4H, m), 2.01 (4H, m), 5.13 (1H, m), 5.27 (1H, m), 5.76 (1H, dd), 6.72 (1H, dd), 7.45 (2H, d), 7.67 (2H, d)

^{The 1} H NMR measurement results of the monomer (m05) are shown below.
^1H NMR (400MHz, DMSO-d6) δ (ppm) = 1.24 (3H,m), 1.65 (2H,m), 1.88 (2H,m), 2.06 (2H,m), 5.25 (1H,dd), 5.59 (1H,m), 5.68 (1H,m), 5.76 (1H,dd), 6.72 (1H,dd), 7.45 (2H,d), 7.69 (2H,d)

^{The 1} H NMR measurement results of the monomer (m06) are shown below.
^1H NMR (400MHz, DMSO-d6) δ (ppm) = 1.47 (4H,m), 1.66 (3H,m), 2.76 (1H,m), 2.90 (1H,m), 5.03 (1H,m), 5.25 (1H,dd), 5.37 (1H,m), 5.76 (1H,dd), 6.72 (1H,dd), 7.45 (2H,d), 7.67 (2H,d)

[Synthesis Example 7: Synthesis of Monomer (m07)]
20.0 g of 4-hydroxybenzoic acid and 16.9 g of triethylamine were dissolved in 100 g of dichloromethane, and a mixed solution of 18.2 g of methacrylic acid chloride and 36.4 g of dichloromethane was added dropwise to the solution in an ice bath. After stirring for 2 hours at 25°C, the solvent was distilled off, and the residue was purified by column chromatography to obtain methacryloyloxybenzoic acid.

10.0 g of methacryloyloxybenzoic acid was dissolved in 60.0 g of tetrahydrofuran, and a mixed solution of 9.2 g of diazabicycloundenose (DBU), 7.1 g of 3-methylcyclohexenol, 11.0 g of carbonyldiimidazole (CDI), and 60.0 g of tetrahydrofuran was added dropwise to the solution under ice cooling. After stirring at 60°C for 4 hours, the solvent was distilled off, 120 g of heptane was added to the residue, and impurities were removed by filtration. The solution was then purified by column chromatography to obtain monomer (m07).

^{The 1} H NMR measurement results of the monomer (m07) are shown below.
^1H NMR (400MHz, DMSO-d6) δ (ppm) = 1.65 (4H,m), 1.94 (2H,m), 2.01 (3H,m), 2.19 (2H,m), 5.13 (1H,m), 5.37 (1H,m), 6.18 (1H,d), 6.43 (1H,d), 7.44 (2H,d), 8.06 (2H,d)

[Synthesis Example 8: Synthesis of Monomer (m08)]
10.0 g of hydroxyacetic acid and 15.3 g of triethylamine were dissolved in 100 g of dichloromethane, and a mixed solution of 26.3 g of benzoyl chloride and 52.6 g of dichloromethane was added dropwise to the solution in an ice bath. After stirring at 25° C. for 2 hours, the solvent was distilled off, and the mixture was purified by column chromatography to obtain intermediate A.

10 g of intermediate A was dissolved in 60.0 g of tetrahydrofuran, and a mixed solution of 9.2 g of diazabicycloundenose (DBU), 7.1 g of 3-methylcyclohexenol, 11.0 g of carbonyldiimidazole (CDI), and 60.0 g of tetrahydrofuran was added dropwise to the solution under ice cooling. After stirring at 60°C for 4 hours, the solvent was distilled off, 120 g of heptane was added to the residue, and impurities were removed by filtration. The mixture was then purified by column chromatography to obtain monomer (m08).

^{The 1} H NMR measurement results of the monomer (m08) are shown below.
^1H NMR (400MHz, DMSO-d6) δ (ppm) = 1.65 (3H,m), 1.70 (2H,m), 1.98 (4H,m), 5.13 (1H,m), 5.21 (2H,m), 5.25 (1H,m), 5.37 (1H,m), 5.76 (1H,dd), 6.72 (1H,dd), 7.45 (2H,d), 7.67 (2H,d)

[Synthesis Examples 9 to 10: Synthesis of Monomers (m09) to (m010)]
Monomers (m09) to (m010) were obtained in the same manner as in the above "Synthesis Example 1: Synthesis of Monomer (m01)" except that the combination of starting materials was changed.

^{The 1} H NMR measurement results of the monomer (m09) are shown below.
^1H NMR (400MHz, DMSO-d6) δ (ppm) = 0.95 (3H, d), 1.64 (1H, m), 1.65 (3H, m), 1.85 (2H, m), 2.03 (2H, m), 5.13 (1H, m), 5.25 (1H, dd), 5.37 (1H, m), 5.76 (1H, dd), 6.72 (1H, dd), 7.45 (2H, d), 7.67 (2H, d)

The ¹ H NMR measurement results of the monomer (m010) are shown below.
^1H NMR (400MHz, DMSO-d6) δ (ppm) = 1.65 (3H,m), 1.70 (2H,m), 1.94 (2H,m), 2.09 (2H,m), 2.48 (3H,s), 5.13 (1H,m), 5.37 (1H,m), 5.60 (1H,dd), 5.72 (1H,dd), 7.37 (1H,m), 7.40 (1H,m), 7.57 (1H,m), 7.78 (1H,m)

<Synthesis of polymer compounds>
The polymer compounds (A0-1) to (A0-10) and (A1-1) to (A1-5) used in this example were each obtained by radical polymerization using monomers that derive the structural units constituting each polymer compound in a predetermined molar ratio.
The weight average molecular weight (Mw) and the molecular weight dispersity (Mw/Mn) of each of the obtained polymer compounds were determined by GPC measurement (converted into standard polystyrene). The results are shown in Table 1.
Furthermore, the copolymer composition ratio (the ratio (molar ratio) of each structural unit in the structural formula) of each of the obtained polymer compounds was determined by carbon-13 nuclear magnetic resonance spectroscopy (600 MHz, ¹³ C-NMR). The results are shown in Table 1.

The structures of polymer compounds (A0-1) to (A0-10) and (A1-1) to (A1-5) are shown below. In each formula, l and m indicate the composition ratio of each structural unit, and l/m = 60/40.

<Preparation of Resist Composition>
(Examples 1 to 16, Comparative Examples 1 to 5)
The components shown in Tables 2 and 3 were mixed and dissolved to prepare resist compositions of each example.

In Tables 2 and 3, the abbreviations have the following meanings. The numbers in brackets [ ] are the amounts used (parts by mass).

(A0)-1 to (A0)-10: the polymer compounds (A0-1) to (A0-10).
(A1)-1 to (A1)-5: the polymeric compounds (A1-1) to (A1-5).

(B)-1: An acid generator comprising the following compound (B1-1).
(B)-2: An acid generator comprising the following compound (B1-2).
(B)-3: An acid generator comprising the following compound (B1-3).
(B)-4: An acid generator comprising the following compound (B1-4).
(B)-5: An acid generator consisting of the following compound (B1-5).
(B)-6: An acid generator consisting of the following compound (B1-6).
(B)-7: An acid generator consisting of the following compound (B1-7).
(D)-1: An acid diffusion controller consisting of the following compound (D1-1).
(S)-1: a mixed solvent of propylene glycol monomethyl ether acetate/propylene glycol monomethyl ether=60/40 (mass ratio).

<Formation of Resist Pattern>
Each resist composition of the examples was applied using a spinner onto an 8-inch silicon substrate that had been treated with hexamethyldisilazane (HMDS), and the substrate was pre-baked (PAB) on a hot plate at a temperature of 110° C. for 60 seconds, followed by drying to form a resist film with a thickness of 50 nm.
Next, the resist film was subjected to drawing (exposure) using an electron beam lithography system JEOL-JBX-9300FS (manufactured by JEOL Ltd.) at an acceleration voltage of 100 kV to form a 1:1 line and space pattern (hereinafter referred to as LS pattern) with a target size of a line width of 50 nm, and then subjected to a post-exposure bake (PEB) treatment at 100° C. for 60 seconds.
Next, alkaline development was carried out at 23° C. for 60 seconds using a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) “NMD-3” (product name, manufactured by Tokyo Ohka Kogyo Co., Ltd.).
Thereafter, the substrate was rinsed with pure water for 15 seconds.
As a result, a 1:1 LS pattern with a line width of 50 nm was formed.

[Evaluation of Optimal Exposure (Eop)]
The optimum exposure dose Eop (μC/cm ² ) for forming an LS pattern of the target size by the above resist pattern forming method was determined. The results are shown in Tables 2 and 3 as "Eop (μC/cm ² )."

[Evaluation of Resolution]
When an LS pattern was formed by gradually increasing the exposure dose from the optimum exposure dose Eop (μC/cm ² ) at which an LS pattern of the target size was formed by the above <Formation of Resist Pattern>, the minimum dimension at which the pattern was resolved was determined using a scanning electron microscope S-9380 (manufactured by Hitachi High-Technologies Corporation). The results are shown in Tables 2 and 3 as "resolution (nm)".

The results shown in Tables 2 to 3 confirm that the resist compositions of Examples 1 to 10 provide higher sensitivity and better resolution in forming resist patterns than the resist compositions of Comparative Examples 1 to 5.

The above describes preferred embodiments of the present invention, but the present invention is not limited to these embodiments. Addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the scope of the attached claims.

Claims

A resist composition which generates an acid upon exposure and changes its solubility in a developer by the action of the acid,
Contains a resin component (A1) whose solubility in a developer changes under the action of an acid,
The resist composition, wherein the resin component (A1) has a structural unit (a0) derived from a compound represented by the following general formula (a0-1):

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; La 01 and La 02 are each independently a single bond or a divalent linking group; Ar is an aromatic ring; Ra 01 is a substituent other than a hydroxy group; m1 is an integer of 0 or more as long as the valence allows; and Rpg is an acid-dissociable group represented by the following general formula (a0-pg).]

[In the formula, * is a bond bonded to -O- in -La 02 -C(═O)-O-; Ra 02 is a hydrogen atom or a hydrocarbon group; C 1 is a secondary carbon atom or a tertiary carbon atom; A is an aliphatic ring having 6 or more carbon atoms; C 2 and C 3 are each independently a carbon atom constituting a carbon-carbon unsaturated bond forming a part of the ring skeleton of the aliphatic ring having 6 or more carbon atoms in A; Ra 03 and Ra 04 are each independently a hydrogen atom or a hydrocarbon group; Ra 05 is a hydrocarbon group; n1 is an integer of 0 or more as far as the valence allows; with the proviso that C 1 does not constitute a part of a crosslinked structure; and when Ra 02 , Ra 03 and Ra 04 are all hydrogen atoms, n1 is an integer of 1 or more.]
2. The resist composition according to claim 1, wherein the structural unit (a0) is a structural unit derived from a compound represented by the following general formula (a0-s1):

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; La 01 and La 02 are each independently a single bond or a divalent linking group; Ar is an aromatic ring; Ra 01 is a substituent other than a hydroxy group; m1 is an integer of 0 or more as long as the valence allows; Cs is a secondary carbon atom; A is an aliphatic ring having 6 or more carbon atoms; C 2 and C 3 are each independently a carbon atom constituting a carbon-carbon unsaturated bond that forms part of the ring skeleton of the aliphatic ring having 6 or more carbon atoms in A; Ra 031 and Ra 041 are each independently a hydrogen atom or a hydrocarbon group; Ra 051 is a hydrocarbon group; n11 is an integer of 0 or more as long as the valence allows; provided that when Ra 031 and Ra 041 are both hydrogen atoms, n11 is an integer of 1 or more.]
2. The resist composition according to claim 1, wherein the structural unit (a0) is a structural unit derived from a compound represented by the following general formula (a0-t1):

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; La 01 and La 02 are each independently a single bond or a divalent linking group; Ar is an aromatic ring; Ra 01 is a substituent other than a hydroxyl group; m1 is an integer of 0 or more as long as the valence allows; Ra 022 is a hydrocarbon group; Ct is a tertiary carbon atom; A is an aliphatic ring having 6 or more carbon atoms; C 2 and C 3 are each independently a carbon atom constituting a carbon-carbon unsaturated bond that forms part of the ring skeleton of the aliphatic ring having 6 or more carbon atoms in A; Ra 032 and Ra 042 are each independently a hydrogen atom or a hydrocarbon group; Ra 052 is a hydrocarbon group; n12 is an integer of 0 or more as long as the valence allows.]
A method for forming a resist pattern, comprising the steps of forming a resist film on a support using the resist composition according to any one of claims 1 to 3, exposing the resist film to light, and developing the exposed resist film to form a resist pattern.
The method for forming a resist pattern according to claim 4, wherein in the step of exposing the resist film, the resist film is exposed to EUV (extreme ultraviolet) or EB (electron beam).
A compound represented by the following general formula (a0-1):

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; La 01 and La 02 are each independently a single bond or a divalent linking group; Ar is an aromatic ring; Ra 01 is a substituent other than a hydroxy group; m1 is an integer of 0 or more as long as the valence allows; and Rpg is an acid-dissociable group represented by the following general formula (a0-pg).]

[In the formula, * is a bond bonded to -O- in -La 02 -C(═O)-O-; Ra 02 is a hydrogen atom or a hydrocarbon group; C 1 is a secondary carbon atom or a tertiary carbon atom; A is an aliphatic ring having 6 or more carbon atoms; C 2 and C 3 are each independently a carbon atom constituting a carbon-carbon unsaturated bond forming a part of the ring skeleton of the aliphatic ring having 6 or more carbon atoms in A; Ra 03 and Ra 04 are each independently a hydrogen atom or a hydrocarbon group; Ra 05 is a hydrocarbon group; n1 is an integer of 0 or more as far as the valence allows; with the proviso that C 1 does not constitute a part of a crosslinked structure; and when Ra 02 , Ra 03 and Ra 04 are all hydrogen atoms, n1 is an integer of 1 or more.]
The compound according to claim 6, represented by the following general formula (a0-s1):

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; La 01 and La 02 are each independently a single bond or a divalent linking group; Ar is an aromatic ring; Ra 01 is a substituent other than a hydroxy group; m1 is an integer of 0 or more as long as the valence allows; Cs is a secondary carbon atom; A is an aliphatic ring having 6 or more carbon atoms; C 2 and C 3 are each independently a carbon atom constituting a carbon-carbon unsaturated bond that forms part of the ring skeleton of the aliphatic ring having 6 or more carbon atoms in A; Ra 031 and Ra 041 are each independently a hydrogen atom or a hydrocarbon group; Ra 051 is a hydrocarbon group; n11 is an integer of 0 or more as long as the valence allows; provided that when Ra 031 and Ra 041 are both hydrogen atoms, n11 is an integer of 1 or more.]
The compound according to claim 6, which is a structural unit derived from a compound represented by the following general formula (a0-t1):

[In the formula, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; La 01 and La 02 are each independently a single bond or a divalent linking group; Ar is an aromatic ring; Ra 01 is a substituent other than a hydroxyl group; m1 is an integer of 0 or more, as long as the valence allows; Ra 022 is an alkyl group or a hydrocarbon group; Ct is a tertiary carbon atom; A is an aliphatic ring having 6 or more carbon atoms; C 2 and C 3 are each independently a carbon atom constituting a carbon-carbon unsaturated bond that forms part of the ring skeleton of the aliphatic ring having 6 or more carbon atoms in A; Ra 032 and Ra 042 are each independently a hydrogen atom or a hydrocarbon group; Ra 052 is a hydrocarbon group; n12 is an integer of 0 or more, as long as the valence allows.]