JP7495404B2 - Actinic ray-sensitive or radiation-sensitive resin composition, resist film, pattern forming method, method for manufacturing electronic device, composition container - Google Patents

Description

The present invention relates to an actinic ray-sensitive or radiation-sensitive resin composition, a resist film, a pattern forming method, a method for manufacturing an electronic device, and a composition container.

After the resist for KrF excimer laser (248 nm), a pattern formation method using chemical amplification has been used to compensate for the decrease in sensitivity due to light absorption. For example, in the positive-type chemical amplification method, first, a photoacid generator contained in the exposed portion is decomposed by light irradiation to generate an acid. Then, in a post-exposure bake (PEB) process or the like, the catalytic action of the generated acid changes the alkali-insoluble group of the resin contained in the actinic ray-sensitive or radiation-sensitive resin composition to an alkali-soluble group, thereby changing the solubility in the developer. Then, development is performed using, for example, a basic aqueous solution. As a result, the exposed portion is removed to obtain a desired pattern.
In order to miniaturize semiconductor elements, the wavelength of exposure light sources has become shorter and the numerical aperture (NA) of projection lenses has become higher, and currently, exposure machines that use an ArF excimer laser having a wavelength of 193 nm as a light source have been developed.
Under these circumstances, various compositions have been proposed for actinic ray- or radiation-sensitive resin compositions (resist compositions).

For example, Patent Document 1 discloses an acid generator containing a salt represented by the following formula (I) as a component used in a resist composition.

JP 2015-024989 A

The present inventors have studied the resist composition described in Patent Document 1 and have found that when a pattern is formed using the resist composition after storage for a specified period of time, many defects occur in the pattern. In other words, it has become clear that the resist composition requires further improvement so as to prevent defects from occurring in the resulting pattern even when the resist composition is used to form a pattern after storage for a specified period of time.

Therefore, an object of the present invention is to provide an actinic ray-sensitive or radiation-sensitive resin composition capable of forming a pattern with reduced defects even after storage for a predetermined period of time.
Another object of the present invention is to provide a resist film and a pattern forming method using the actinic ray-sensitive or radiation-sensitive resin composition, as well as a method for manufacturing an electronic device using the pattern forming method.
Another object of the present invention is to provide a composition container containing the actinic ray-sensitive or radiation-sensitive resin composition.

As a result of intensive research into solving the above problems, the inventors have discovered that the above problems can be solved by the following configuration.

[1] An actinic ray-sensitive or radiation-sensitive resin composition comprising a resin that decomposes under the action of an acid to increase its polarity, a compound that generates an acid when irradiated with actinic rays or radiation, and a solvent,
the compound that generates an acid upon irradiation with actinic rays or radiation includes at least one selected from the group consisting of compounds (I) to (III) described below,
An actinic ray-sensitive or radiation-sensitive resin composition having a water content of 1.00 mass % or less, based on the total mass of the composition.
[2] The actinic ray-sensitive or radiation-sensitive resin composition according to [1], wherein the water content is 0.50 mass% or less, based on the total mass of the composition.
[3] The actinic ray-sensitive or radiation-sensitive resin composition according to [1] or [2], wherein the water content is 0.30 mass% or less based on the total mass of the composition.
[4] The actinic ray-sensitive or radiation-sensitive resin composition according to any one of [1] to [3], wherein the water content is 0.03 to 0.30 mass % based on the total mass of the composition.
[5] The actinic ray-sensitive or radiation-sensitive resin composition according to any one of [1] to [4], wherein the quantitative ratio T represented by the following formula (1X) is 4.0 to 500.0:
Formula (1X): Amount ratio T = content (mass%) of the compound selected from the group consisting of the above-mentioned compounds (I) to (III) relative to the solid content in the composition / water content (mass%) relative to the total mass of the composition
[6] A resist film formed using the actinic ray-sensitive or radiation-sensitive resin composition according to any one of [1] to [5].
[7] A process for forming a resist film on a support using the actinic ray-sensitive or radiation-sensitive resin composition according to any one of [1] to [5];
exposing the resist film to light;
and developing the exposed resist film with a developer.
[8] A method for manufacturing an electronic device, comprising the pattern forming method according to [7].
[9] A composition container comprising a container and the actinic ray-sensitive or radiation-sensitive resin composition according to any one of [1] to [5] contained in the container.
[10] The composition container according to [9], wherein a material of a region in the container that comes into contact with the actinic ray-sensitive or radiation-sensitive resin composition is a resin.
[11] The composition container according to [9] or [10], wherein a material of a region in the container that comes into contact with the actinic ray-sensitive or radiation-sensitive resin composition is one or more selected from the group consisting of polyolefin resins and fluorine atom-containing polyolefin resins.

According to the present invention, there is provided an actinic ray-sensitive or radiation-sensitive resin composition capable of forming a pattern with reduced defects even after storage for a predetermined period of time.
Furthermore, according to the present invention, there can be provided a resist film and a pattern forming method using the above-mentioned actinic ray-sensitive or radiation-sensitive resin composition, and a method for manufacturing an electronic device using the above-mentioned pattern forming method.
Furthermore, according to the present invention, there is provided a composition container containing the actinic ray-sensitive or radiation-sensitive resin composition.

FIG. 1 is a schematic diagram for explaining an evaluation method for evaluating defects after pattern formation, which is an example of a defect observed with a critical dimension scanning electron microscope (SEM). FIG. 11 is a schematic diagram for explaining an evaluation method for evaluating defects after pattern formation, which is another example of a defect observed with a critical dimension scanning electron microscope (SEM).

The present invention will be described in detail below.
The following description of the components may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment.
In the present specification, the notation of groups (atomic groups) that does not indicate whether they are substituted or unsubstituted includes both unsubstituted and substituted groups, unless it is contrary to the spirit of the present invention. For example, the term "alkyl group" includes not only alkyl groups that do not have a substituent (unsubstituted alkyl groups), but also alkyl groups that have a substituent (substituted alkyl groups). In addition, the term "organic group" in the present specification refers to a group that contains at least one carbon atom.
Unless otherwise specified, the substituent is preferably a monovalent substituent.
In this specification, "actinic rays" or "radiation" refers to, for example, the emission line spectrum of a mercury lamp, far ultraviolet rays represented by excimer lasers, extreme ultraviolet rays (EUV light: extreme ultraviolet), X-rays, and electron beams (EB: electron beam), etc. In this specification, "light" refers to actinic rays or radiation.
In this specification, unless otherwise specified, "exposure" includes not only exposure to the emission line spectrum of a mercury lamp, far ultraviolet light represented by an excimer laser, extreme ultraviolet light, X-rays, EUV light, and the like, but also drawing with particle beams such as electron beams and ion beams.
In this specification, the word "to" is used to mean that the numerical values before and after it are included as the lower limit and upper limit.
The bonding direction of the divalent group described in this specification is not limited unless otherwise specified. For example, when Y is -COO- in a compound represented by the general formula "X-Y-Z", Y may be -CO-O- or -O-CO-. In addition, the above compound may be "X-CO-O-Z" or "X-O-CO-Z".

In this specification, (meth)acrylate refers to acrylate and methacrylate, and (meth)acrylic refers to acrylic and methacrylic.
In this specification, the weight average molecular weight (Mw), number average molecular weight (Mn), and dispersity (also referred to as molecular weight distribution) (Mw/Mn) of a resin are defined as polystyrene-equivalent values measured using a Gel Permeation Chromatography (GPC) device (HLC-8120GPC manufactured by Tosoh Corporation) (solvent: tetrahydrofuran, flow rate (sample injection amount): 10 μL, column: TSK gel Multipore HXL-M manufactured by Tosoh Corporation, column temperature: 40° C., flow rate: 1.0 mL/min, detector: refractive index detector).

In this specification, the acid dissociation constant (pKa) refers to the pKa in an aqueous solution, and specifically, is a value calculated using the following software package 1 based on a database of Hammett's substituent constants and known literature values. All pKa values described in this specification are values calculated using this software package.

Software Package 1: Advanced Chemistry Development (ACD/Labs) Software V8.14 for Solaris (1994-2007 ACD/Labs).

On the other hand, pKa can also be obtained by molecular orbital calculation. A specific example of this method is a method of calculating H ⁺ dissociation free energy in an aqueous solution based on a thermodynamic cycle. The H ⁺ dissociation free energy can be calculated, for example, by DFT (density functional theory), but various other methods have been reported in literature, and the calculation method is not limited to this. There are several software programs that can perform DFT, and Gaussian16 is an example.

As described above, the pKa in this specification refers to a value calculated using the software package 1 based on a database of Hammett's substituent constants and known literature values. However, when the pKa cannot be calculated by this method, a value obtained by Gaussian 16 based on DFT (density functional theory) is adopted.
In addition, the pKa in this specification refers to "pKa in an aqueous solution" as described above, but when the pKa in an aqueous solution cannot be calculated, "pKa in a dimethyl sulfoxide (DMSO) solution" will be adopted.

As used herein, halogen atoms include, for example, fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[Actinic ray- or radiation-sensitive resin composition]
[0043] The actinic ray-sensitive or radiation-sensitive resin composition of the present invention (hereinafter also referred to as "resist composition") is characterized in that it contains one or more compounds (hereinafter also referred to as "photoacid generator B") selected from the group consisting of compounds (I) to (III) described below, as a compound that generates an acid upon irradiation with actinic rays or radiation (hereinafter also referred to simply as a "photoacid generator"), and that the water content of the resist composition is 1.00 mass % or less, relative to the total mass of the composition.

Photoacid generators with high hydrophilicity tend to have strong aggregating properties due to their high hydrophilicity. As for photoacid generators containing a polyvalent (e.g., divalent) salt structure in the molecule, such as the photoacid generator represented by the above general formula (I) used in Patent Document 1 and the above photoacid generator B, it is assumed that photoacid generators containing a polyvalent (e.g., divalent) salt structure in the molecule have strong aggregating properties due to their high hydrophilicity due to their salt structure, and when they are added to a resist composition, they tend to form aggregates with trace amounts of moisture contained in the resist composition as nuclei. For this reason, when a resist composition containing such a photoacid generator and having a high water content is stored for a certain period of time, a large number of aggregates of the photoacid generator are generated in the resist composition, and as a result, the pattern formed using the resist composition is thought to have many defects.
The present inventors have recently found that in a resist composition containing a photoacid generator that contains a polyvalent salt structure in its molecule, when the water content in the resist composition is 1.00 mass % or less relative to the total mass of the composition, the formation of aggregates of the photoacid generator is significantly suppressed. In other words, it has been found that the resist composition enables the formation of a pattern with excellent defect suppression ability.

As described below, the resist composition of the present invention preferably has a water content of 0.03% by mass or more relative to the total mass of the composition, in order to further suppress defects in the resulting pattern. As described above, a photoacid generator containing a polyvalent salt structure in the molecule has high hydrophilicity due to its salt structure, and therefore has strong coagulation properties, and may aggregate with other photoacid generators (i.e., self-aggregate). If the water content of the resist composition is 0.03% by mass or more relative to the total mass of the composition, aggregation between other photoacid generators can be suppressed, and a pattern with more suppressed defects can be formed. In particular, when the water content of the resist composition of the present invention is 0.03 to 0.30% by mass relative to the total mass of the composition, the defect suppression ability of the formed pattern is remarkably excellent.

As described later, in the case of a container for storing the resist composition of the present invention, the material of the region in contact with the resist composition (for example, the inner wall of the container that contains the resist composition and/or the flow path of the resist composition) is preferably a resin. For example, when the material of the region in contact with the resist composition of the container is glass, the moisture contained in the resist composition is likely to adhere to the surface of the glass because glass is highly hydrophilic. Photoacid generators containing a polyvalent salt structure in the molecule have strong coagulation properties due to their high hydrophilicity caused by the salt structure, and are likely to form aggregates with the moisture attached to the glass surface as a nucleus. In contrast, when the material of the region in contact with the resist composition of the container is a resin (preferably one or more resins selected from the group consisting of polyolefin resins and fluorine atom-containing polyolefin resins), adhesion of moisture to the above region is suppressed, making it difficult for the photoacid generator to form aggregates, and a pattern with more suppressed defects can be formed.

The resist composition of the present invention will be described in detail below.
The resist composition of the present invention may be a positive resist composition or a negative resist composition. Furthermore, it may be a resist composition for alkali development or a resist composition for organic solvent development.
The resist composition of the present invention is typically a chemically amplified resist composition.

[Moisture content]
The water content of the resist composition of the present invention is 1.00% by mass or less, preferably 0.50% by mass or less, and more preferably 0.30% by mass or less, based on the total mass of the composition. The lower limit is, for example, 0.00% by mass or more, based on the total mass of the composition, and from the viewpoint of further suppressing defects in the pattern to be formed, is preferably 0.01% by mass or more, and more preferably 0.03% by mass or more. The water content can be measured using a Karl Fischer moisture meter (for example, MKC-510N manufactured by Kyoto Electronics Manufacturing Co., Ltd.).

In order to further suppress defects in the pattern formed, the resist composition of the present invention preferably has a quantitative ratio T represented by the following formula (1X) of 1.0 to 1600.0, more preferably 2.0 to 1000.0, and even more preferably 4.0 to 500.0.
Formula (1X): Amount ratio T = content (mass %) of the compound (photoacid generator B) selected from the group consisting of compounds (I) to (III) relative to the solid content in the composition / water content (mass %) relative to the total mass of the composition

The various components of the resist composition of the present invention are described in detail below.
[Photoacid generator]
First, a compound that generates an acid upon irradiation with actinic rays or radiation (a photoacid generator) will be described below.
In the resist composition of the present invention, the content of the photoacid generator (when a plurality of types are contained, the total content thereof) is preferably 0.1 to 45.0 mass %, more preferably 2.0 to 40.0 mass %, and even more preferably 4.0 to 30.0 mass %, based on the total solid content of the composition.
The term "solid content" refers to components that form a resist film and does not include solvents. In addition, any component that forms a resist film is considered to be a solid content even if it is in a liquid state.

The photoacid generator contains one or more compounds (photoacid generator B) selected from the group consisting of compounds (I) to (III) described below.
The content of the photoacid generator B is preferably from 0.1 to 45.0% by mass, more preferably from 2.0 to 40.0% by mass, and even more preferably from 4.0 to 30.0% by mass, based on the total solid content of the composition.
The photoacid generator B may be used alone or in combination of two or more. When two or more types are used, the total content is preferably within the above-mentioned suitable content range.

The resist composition of the present invention may further contain a photoacid generator (hereinafter also referred to as "photoacid generator C") other than the photoacid generator B. The photoacid generator C is not particularly limited, but is preferably a compound selected from the group consisting of the compounds represented by general formula (1) described below and the compounds represented by general formula (2) described below, in that the LWR performance of the formed pattern is more excellent.
The content of the photoacid generator C is preferably 0.1 to 20.0 mass %, more preferably 0.1 to 15.0 mass %, even more preferably 0.1 to 12.0 mass %, and particularly preferably 0.1 to 8.0 mass %, based on the total solid content of the composition.
The photoacid generator C may be used alone or in combination of two or more. When two or more types are used, the total content is preferably within the above-mentioned suitable content range.

Below, photoacid generator B and photoacid generator C are each explained.

<Photoacid Generator B>
The photoacid generator B is a compound selected from the group consisting of the following compounds (I) to (III).

The pattern formed by the resist composition containing the photoacid generator B has excellent LWR performance. The photoacid generator B contains both a structural part X having a function corresponding to the photoacid generator and a structural part (structural part Y or structural part Z) having a function corresponding to the acid diffusion controller in one molecule, so that the presence ratio of each of the structural parts can be constant in the resist film. As a result, the concentration distribution of the photoacid generator and the acid diffusion controller can be made uniform in the resist film, so that the amount and diffusion of acid during exposure are likely to be uniform, and the width of the pattern obtained after development is likely to be stable. In other words, the LWR performance of the formed pattern is excellent.
Compounds (I) to (III) will be described below.

(Compound (I))
Compound (I) will be described below.
Compound (I): a compound having each of the following structural moieties X and Y, which generates an acid containing the following first acidic moiety derived from the following structural moiety X and the following second acidic moiety derived from the following structural moiety Y upon irradiation with actinic rays or radiation. Structural moiety X: a structural moiety consisting of an anionic moiety A ₁ ^- and a cationic moiety M ₁ ⁺ , and which forms a first acidic moiety represented by HA ₁ upon irradiation with actinic rays or radiation. Structural moiety Y: a structural moiety consisting of an anionic moiety A ₂ ^- and a cationic moiety M ₂ ⁺ , and which forms a second acidic moiety represented by HA ₂ having a structure different from the first acidic moiety formed at the structural moiety X upon irradiation with actinic rays or radiation. However, compound (I) satisfies the following condition I.
Condition I: Compound PI, which is obtained by replacing the cationic moiety M ₁ ⁺ in the structural moiety X and the cationic moiety M ₂ ⁺ in the structural moiety Y in compound (I) with H ⁺ , has an acid dissociation constant a1 derived from the acidic moiety represented by HA ₁ , which is obtained by replacing the cationic moiety M ₁ ⁺ in the structural moiety X with H ⁺ , and an acid dissociation constant a2 derived from the acidic moiety represented by HA ₂ , which is obtained by replacing the cationic moiety M ₂ ⁺ in the structural moiety Y with H ⁺ , and the acid dissociation constant a2 is greater than the acid dissociation constant a1.
The acid dissociation constant a1 and the acid dissociation constant a2 are determined by the method described above. More specifically, when the acid dissociation constant of compound PI is determined, the pKa of compound PI (compound PI corresponds to a "compound having HA ₁ and HA ₂ ") when it becomes a "compound having A ₁ ^- and HA ₂ " is the acid dissociation constant a1, and the pKa of the "compound having A ₁ ^- and HA ₂ " when it becomes a "compound having A ₁ ^- and A ₂ ^- " is the acid dissociation constant a2.
The compound PI corresponds to an acid generated by irradiating compound (I) with actinic rays or radiation.

In order to obtain a more excellent LWR performance of the pattern formed, the difference between the acid dissociation constant a1 and the acid dissociation constant a2 in the compound PI is preferably 2.0 or more, more preferably 3.0 or more. The upper limit of the difference between the acid dissociation constant a1 and the acid dissociation constant a2 is not particularly limited, but is, for example, 15.0 or less.

In addition, in the above compound PI, the acid dissociation constant a2 is, for example, 6.5 or less, and is preferably 2.0 or less, and more preferably 1.0 or less, in terms of superior stability of the cationic moiety of compound (I) in the resist composition. The lower limit of the acid dissociation constant a2 is, for example, -3.5 or more, and preferably -2.0 or more.

In addition, in order to obtain a pattern having better LWR performance, the acid dissociation constant a1 of the compound PI is preferably 2.0 or less, more preferably 0.5 or less, and even more preferably -0.1 or less. The lower limit of the acid dissociation constant a1 is preferably -15.0 or more.

Compound (I) is not particularly limited, but examples thereof include compounds represented by the following general formula (Ia).
_M11 ⁺ _A11 ^- _{-L1 -A12} ^- _M12 ⁺ (Ia)

In general formula (Ia), "M ₁₁ ⁺ A ₁₁ ^- " and "A ₁₂ ^- M ₁₂ ⁺ " correspond to the structural moiety X and the structural moiety Y, respectively. When irradiated with actinic rays or radiation, compound (Ia) generates an acid represented by HA ₁₁ -L ₁ -A ₂₁ H. That is, "M ₁₁ ⁺ A ₁₁ ^- " forms a first acidic moiety represented by HA ₁₁ , and "A ₁₂ ^- M ₁₂ ⁺ " forms a second acidic moiety represented by HA ₁₂ , which has a structure different from that of the first acidic moiety.

In formula (Ia), M ₁₁ ⁺ and M ₁₂ ⁺ each independently represent an organic cation.
A ₁₁ ^- and A ₁₂ ^- each independently represent an anionic functional group, provided that A ₁₂ ^- represents a structure different from the anionic functional group represented by A ₁₁ ^- .
_L1 represents a divalent linking group.
However, in the compound PIa (HA ₁₁ -L ₁ -A ₁₂ H) obtained by replacing the organic cations represented by M ₁₁ ⁺ and M ₁₂ ⁺ in the above general formula (Ia) with H ⁺ , the acid dissociation constant a2 derived from the acidic site represented by A ₁₂ H is larger than the acid dissociation constant a1 derived from the acidic site represented by HA _11. The preferred values of the acid dissociation constant a1 and the acid dissociation constant a2 are as described above.

In general formula (Ia), the organic cations represented by M ₁₁ ⁺ and M ₁₂ ⁺ are as described later.

Examples of the anionic functional groups represented by A ₁₁ ^- and A ₁₂ ^- include groups represented by the following general formulae (B-1) to (B-13).

In formulae (B-1), (B-2), (B-4), (B-5), and (B-12), R ^X1 represents a substituent.
R ^X1 is preferably a linear, branched, or cyclic alkyl group.
The alkyl group preferably has 1 to 15 carbon atoms, and more preferably has 1 to 10 carbon atoms.
The alkyl group may have a substituent. The substituent is preferably a fluorine atom or a cyano group. When the alkyl group has a fluorine atom as a substituent, it may be a perfluoroalkyl group.
In addition, the alkyl group may have a carbon atom substituted with a carbonyl group.

In formula (B-3), R ^X4 represents a substituent.
R ^X4 is preferably a linear, branched or cyclic alkyl group.
The alkyl group preferably has 1 to 15 carbon atoms, and more preferably has 1 to 10 carbon atoms.
The alkyl group may have a substituent. The substituent is preferably a fluorine atom or a cyano group. When R ^X4 is an alkyl group having a fluorine atom as a substituent, it is preferably not a perfluoroalkyl group.
In addition, the alkyl group may have a carbon atom substituted with a carbonyl group.

In formulae (B-7) and (B-11), R ^{1 X2} represents a hydrogen atom or a substituent other than a fluorine atom or a perfluoroalkyl group.
As the substituent other than a fluorine atom and a perfluoroalkyl group represented by R ^X2 , a linear, branched or cyclic alkyl group is preferable.
The alkyl group preferably has 1 to 15 carbon atoms, and more preferably has 1 to 10 carbon atoms.
The alkyl group may have a substituent other than a fluorine atom.

In formula (B-8), R ^XF1 represents a hydrogen atom, a fluorine atom, or a perfluoroalkyl group, provided that at least one of the multiple R ^XF1 represents a fluorine atom or a perfluoroalkyl group.
The perfluoroalkyl group represented by R ^{2 XF1} preferably has 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 6 carbon atoms.

In formula (B-10), R ^XF2 represents a fluorine atom or a perfluoroalkyl group.
The perfluoroalkyl group represented by R ^{2 XF2} preferably has 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 6 carbon atoms.

In general formula (B-9), n represents an integer from 0 to 4.

The combination of the anionic functional groups represented by A ₁₁ ^- and A ₁₂ ^- is not particularly limited, but for example, when A ₁₁ ^- is a group represented by general formula (B-8) or (B-10), the anionic functional group represented by A ₁₂ ^- includes groups represented by general formulas (B-1) to (B-7), (B-9), or (B-11) to (B-13), and when A ₁₁ ^- is a group represented by general formula (B-7), the anionic functional group represented by A ₁₂ ^- includes groups represented by general formula (B-6).

In the general formula (Ia), the divalent linking group represented by L ₁ is not particularly limited, and examples thereof include -CO-, -NR-, -CO-, -O-, an alkylene group (preferably having 1 to 6 carbon atoms, which may be linear or branched), a cycloalkylene group (preferably having 3 to 15 carbon atoms), an alkenylene group (preferably having 2 to 6 carbon atoms), a divalent aliphatic heterocyclic group (preferably a 5- to 10-membered ring having at least one N atom, O atom, S atom, or Se atom in the ring structure, more preferably a 5- to 7-membered ring, and even more preferably a 5- to 6-membered ring), and a divalent linking group combining a plurality of these. The R is a hydrogen atom or a monovalent substituent. The monovalent substituent is not particularly limited, but for example, an alkyl group (preferably having 1 to 6 carbon atoms) is preferable.
These divalent linking groups may further contain a group selected from the group consisting of -S-, -SO-, and -SO ₂ -.
The alkylene group, the cycloalkylene group, the alkenylene group, and the divalent aliphatic heterocyclic group may be substituted with a substituent, such as a halogen atom (preferably a fluorine atom).

In the general formula (Ia), preferred forms of the organic cations represented by M ₁₁ ⁺ and M ₁₂ ⁺ will be described in detail.
The organic cations represented by M ₁₁ ⁺ and M ₁₂ ⁺ are each independently preferably an organic cation represented by general formula (ZaI) (cation (ZaI)) or an organic cation represented by general formula (ZaII) (cation (ZaII)).

In the above general formula (ZaI),
R ²⁰¹ , R ²⁰² and R ²⁰³ each independently represent an organic group.
The number of carbon atoms in the organic group represented by R ²⁰¹ , R ²⁰² , and R ²⁰³ is usually 1 to 30, and preferably 1 to 20. Two of R ²⁰¹ to R ²⁰³ may be bonded to form a ring structure, and the ring may contain an oxygen atom, a sulfur atom, an ester group, an amide group, or a carbonyl group. Examples of the group formed by bonding two of R ²⁰¹ to R ²⁰³ include an alkylene group (e.g., a butylene group and a pentylene group) and -CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -.

Suitable embodiments of the organic cation in general formula (ZaI) include the cation (ZaI-1), cation (ZaI-2), the organic cation represented by general formula (ZaI-3b) (cation (ZaI-3b)), and the organic cation represented by general formula (ZaI-4b) (cation (ZaI-4b)), which will be described later.

First, the cation (ZaI-1) will be described.
The cation (ZaI-1) is an arylsulfonium cation in which at least one of R ²⁰¹ to R ²⁰³ in the above general formula (ZaI) is an aryl group.
In the arylsulfonium cation, all of R ₂₀₁ to R ₂₀₃ may be aryl groups, or some of R ₂₀₁ to R ₂₀₃ may be aryl groups, with the remainder being alkyl groups or cycloalkyl groups.
In addition, one of R ₂₀₁ to R ₂₀₃ may be an aryl group, and the remaining two of R ²⁰¹ to R ²⁰³ may be bonded to form a ring structure, which may contain an oxygen atom, a sulfur atom, an ester group, an amide group, or a carbonyl group in the ring. Examples of the group formed by bonding two of R ²⁰¹ to R ²⁰³ include alkylene groups in which one or more methylene groups may be substituted with oxygen atoms, sulfur atoms, ester groups, amide groups, and/or carbonyl groups (e.g., butylene group, pentylene group, or -CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -).
Examples of the arylsulfonium cation include triarylsulfonium cations, diarylalkylsulfonium cations, aryldialkylsulfonium cations, diarylcycloalkylsulfonium cations, and aryldicycloalkylsulfonium cations.

The aryl group contained in the arylsulfonium cation is preferably a phenyl group or a naphthyl group, more preferably a phenyl group. The aryl group may be an aryl group having a heterocyclic structure with an oxygen atom, a nitrogen atom, or a sulfur atom. Examples of the heterocyclic structure include a pyrrole residue, a furan residue, a thiophene residue, an indole residue, a benzofuran residue, and a benzothiophene residue. When the arylsulfonium cation has two or more aryl groups, the two or more aryl groups may be the same or different.
The alkyl group or cycloalkyl group that the arylsulfonium cation optionally has is preferably a linear alkyl group having 1 to 15 carbon atoms, a branched alkyl group having 3 to 15 carbon atoms, or a cycloalkyl group having 3 to 15 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a t-butyl group, a cyclopropyl group, a cyclobutyl group, and a cyclohexyl group.

Substituents that the aryl group, alkyl group, and cycloalkyl group of R ²⁰¹ to R ²⁰³ may have each independently include an alkyl group (e.g., 1 to 15 carbon atoms), a cycloalkyl group (e.g., 3 to 15 carbon atoms), an aryl group (e.g., 6 to 14 carbon atoms), an alkoxy group (e.g., 1 to 15 carbon atoms), a cycloalkylalkoxy group (e.g., 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, and a phenylthio group.
The above-mentioned substituents may further have a substituent if possible. For example, the above-mentioned alkyl group may have a halogen atom as a substituent to form a halogenated alkyl group such as a trifluoromethyl group.

Next, the cation (ZaI-2) will be described.
Cation (ZaI-2) is a cation in which R ²⁰¹ to R ²⁰³ in formula (ZaI) each independently represent an organic group not having an aromatic ring. Here, the aromatic ring also includes an aromatic ring containing a heteroatom.
The organic group not having an aromatic ring represented by R ²⁰¹ to R ²⁰³ generally has 1 to 30 carbon atoms, and preferably has 1 to 20 carbon atoms.
R ²⁰¹ to R ²⁰³ are each independently preferably an alkyl group, a cycloalkyl group, an allyl group, or a vinyl group, more preferably a linear or branched 2-oxoalkyl group, a 2-oxocycloalkyl group, or an alkoxycarbonylmethyl group, and still more preferably a linear or branched 2-oxoalkyl group.

Examples of the alkyl group and cycloalkyl group for R ²⁰¹ to R ²⁰³ include linear alkyl groups having 1 to 10 carbon atoms or branched alkyl groups having 3 to 10 carbon atoms (e.g., methyl, ethyl, propyl, butyl, and pentyl groups), and cycloalkyl groups having 3 to 10 carbon atoms (e.g., cyclopentyl, cyclohexyl, and norbornyl groups).
R ²⁰¹ to R ²⁰³ may be further substituted with a halogen atom, an alkoxy group (eg, having 1 to 5 carbon atoms), a hydroxyl group, a cyano group, or a nitro group.

Next, the cation (ZaI-3b) will be described.
The cation (ZaI-3b) is a cation represented by the following general formula (ZaI-3b).

In general formula (ZaI-3b),
R _1c to R _5c each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an alkylcarbonyloxy group, a cycloalkylcarbonyloxy group, a halogen atom, a hydroxyl group, a nitro group, an alkylthio group, or an arylthio group.
R _6c and R _7c each independently represent a hydrogen atom, an alkyl group (such as a t-butyl group), a cycloalkyl group, a halogen atom, a cyano group, or an aryl group.
R _x and R _y each independently represent an alkyl group, a cycloalkyl group, a 2-oxoalkyl group, a 2-oxocycloalkyl group, an alkoxycarbonylalkyl group, an allyl group, or a vinyl group.

Any two or more of R _1c to R _5c , R _5c and R _6c , R _6c and R _7c , R _5c and R _x , and R _x and R _y may be bonded to each other to form a ring, and each of these rings may independently contain an oxygen atom, a sulfur atom, a ketone group, an ester bond, or an amide bond.
Examples of the ring include an aromatic or non-aromatic hydrocarbon ring, an aromatic or non-aromatic heterocycle, and a polycyclic condensed ring formed by combining two or more of these rings. Examples of the ring include a 3- to 10-membered ring, preferably a 4- to 8-membered ring, and more preferably a 5- or 6-membered ring.

The group formed by combining any two or more of R _1c to R _5c , R _6c and R _7c , and R _x and R _y includes alkylene groups such as butylene and pentylene, in which the methylene group may be substituted with a heteroatom such as an oxygen atom.
The groups formed by combining _R5c and _R6c , and _R5c and _Rx are preferably a single bond or an alkylene group. Examples of the alkylene group include a methylene group and an ethylene group.

Next, the cation (ZaI-4b) will be described.
The cation (ZaI-4b) is a cation represented by the following general formula (ZaI-4b).

In general formula (ZaI-4b),
l represents an integer of 0 to 2.
r represents an integer of 0 to 8.
R ₁₃ represents a hydrogen atom, a fluorine atom, a hydroxyl group, an alkyl group, an alkoxy group, an alkoxycarbonyl group, or a group having a cycloalkyl group (which may be a cycloalkyl group itself or a group containing a cycloalkyl group as a part). These groups may have a substituent.
R ₁₄ represents a hydroxyl group, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkylcarbonyl group, an alkylsulfonyl group, a cycloalkylsulfonyl group, or a group having a cycloalkyl group (may be a cycloalkyl group itself, or a group containing a cycloalkyl group as a part). These groups may have a substituent. When there are a plurality of R ₁₄ , each independently represents the above group such as a hydroxyl group.
Each R ₁₅ independently represents an alkyl group, a cycloalkyl group, or a naphthyl group. These groups may have a substituent. Two R ₁₅ may be bonded to each other to form a ring. When two R ₁₅ are bonded to each other to form a ring, the ring skeleton may contain a heteroatom such as an oxygen atom or a nitrogen atom. In one embodiment, it is preferable that two R ₁₅ are alkylene groups and are bonded to each other to form a ring structure.

In general formula (ZaI-4b), the alkyl groups of R ₁₃ , R ₁₄ and R ₁₅ are linear or branched. The number of carbon atoms in the alkyl group is preferably 1 to 10. The alkyl group is more preferably a methyl group, an ethyl group, an n-butyl group, a t-butyl group or the like.

Next, general formula (ZaII) will be described.
In formula (ZaII), R ²⁰⁴ and R ²⁰⁵ each independently represent an aryl group, an alkyl group or a cycloalkyl group.
The aryl group of R ²⁰⁴ and R ²⁰⁵ is preferably a phenyl group or a naphthyl group, more preferably a phenyl group. The aryl group of R ²⁰⁴ and R ²⁰⁵ may be an aryl group having a heterocycle with an oxygen atom, a nitrogen atom, or a sulfur atom. Examples of the skeleton of the aryl group having a heterocycle include pyrrole, furan, thiophene, indole, benzofuran, and benzothiophene.
The alkyl group and cycloalkyl group of R ²⁰⁴ and R ²⁰⁵ are preferably a linear alkyl group having 1 to 10 carbon atoms or a branched alkyl group having 3 to 10 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group, a butyl group, or a pentyl group), or a cycloalkyl group having 3 to 10 carbon atoms (e.g., a cyclopentyl group, a cyclohexyl group, or a norbornyl group).

The aryl group, alkyl group, and cycloalkyl group of R ²⁰⁴ and R ²⁰⁵ may each independently have a substituent. Examples of the substituent that the aryl group, alkyl group, and cycloalkyl group of R ²⁰⁴ and R ²⁰⁵ may have include an alkyl group (e.g., carbon number 1 to 15), a cycloalkyl group (e.g., carbon number 3 to 15), an aryl group (e.g., carbon number 6 to 15), an alkoxy group (e.g., carbon number 1 to 15), a halogen atom, a hydroxyl group, and a phenylthio group.

(Compound (II))
Next, compound (II) will be described.
Compound (II): A compound having two or more of the structural moieties X and the structural moiety Y, which generates an acid containing two or more of the first acidic moieties derived from the structural moiety X and the second acidic moiety derived from the structural moiety Y when irradiated with actinic rays or radiation. However, compound (II) satisfies the following condition II.
Condition II: Compound PII, which is obtained by replacing the cationic moiety M ₁ ⁺ in the structural moiety X and the cationic moiety M ₂ ⁺ in the structural moiety Y in compound (II) with H ⁺ , has an acid dissociation constant a1 derived from the acidic moiety represented by HA ₁ obtained by replacing the cationic moiety M ₁ ⁺ in the structural moiety X with H ⁺ , and an acid dissociation constant a2 derived from the acidic moiety represented by HA ₂ obtained by replacing the cationic moiety M ₂ ⁺ in the structural moiety Y with H ⁺ , and the acid dissociation constant a2 is greater than the acid dissociation constant a1.
The acid dissociation constant a1 and the acid dissociation constant a2 are determined by the method described above.
Here, the acid dissociation constant a1 and the acid dissociation constant a2 of the compound PII will be described in more detail. When the compound (II) is, for example, a compound that generates an acid having two of the first acidic sites derived from the structural site X and one of the second acidic sites derived from the structural site Y, the compound PII corresponds to a "compound having two HA ₁ and HA ₂ ". When the acid dissociation constant of this compound PII is calculated, the pKa when the compound PII becomes a "compound having one A ₁ ^- and one HA ₁ and HA ₂ " is the acid dissociation constant a1, and the pKa when the "compound having two A ₁ ^- and HA ₂ " becomes a "compound having two A ₁ ^- and A ₂ ^-" is the acid dissociation constant a2. In other words, when the compound PII has a plurality of acid dissociation constants derived from the acidic site represented by _HA1 obtained by replacing the cationic site M ₁ ⁺ in the structural site X with H ⁺ , the smallest one is regarded as the acid dissociation constant a1.

The compound PII corresponds to an acid generated by irradiating the compound (II) with actinic rays or radiation.
Compound (II) may have a plurality of the structural moieties Y.

In order to obtain a more excellent LWR performance of the pattern formed, the difference between the acid dissociation constant a1 and the acid dissociation constant a2 in the compound PII is preferably 2.0 or more, more preferably 3.0 or more. The upper limit of the difference between the acid dissociation constant a1 and the acid dissociation constant a2 is not particularly limited, but is, for example, 15.0 or less.

In addition, in the compound PII, the acid dissociation constant a2 is, for example, 6.5 or less, and is preferably 2.0 or less, and more preferably 1.0 or less, in terms of superior stability of the cationic moiety of compound (I) in the resist composition. The lower limit of the acid dissociation constant a2 is, for example, -3.5 or more, and preferably -2.0 or more.

In addition, in order to obtain a pattern having better LWR performance, the acid dissociation constant a1 of the compound PII is preferably 2.0 or less, more preferably 0.5 or less, and even more preferably -0.1 or less. The lower limit of the acid dissociation constant a1 is preferably -15.0 or more.

Compound (II) is not particularly limited, and examples thereof include compounds represented by the following general formula (IIa):

In general formula (Ia), "M ₂₁ ⁺ A ₂₁ ^- " and "A ₂₂ ^- M ₂₂ ⁺ " correspond to the structural moiety X and the structural moiety Y, respectively. When irradiated with actinic rays or radiation, compound (IIa) generates an acid represented by the following general formula (IIa-1). That is, "M ₂₁ ⁺ A ₂₁ ^- " forms a first acidic moiety represented by HA ₂₁ , and "A ₂₂ ^- M ₂₂ ⁺ " forms a second acidic moiety represented by HA ₂₂ , which has a structure different from that of the first acidic moiety.

In formula (IIa), M ₂₁ ⁺ and M ₂₂ ⁺ each independently represent an organic cation.
A ₂₁ ^{- and} A ₂₂ ^- each independently represent _an anionic functional group.
represents a structure different from the anionic functional group represented by A ₂₁ ^- .
_L2 represents an organic group having a valence of (n1+n2).
n1 represents an integer of 2 or more; and n2 represents an integer of 1 or more.
However, in the compound PIIa (corresponding to the compound represented by the above general formula (IIa-1)) obtained by replacing the organic cations represented by M ₂₁ ⁺ and M ₂₂ ⁺ in the above general formula (IIa) below with H ⁺ , the acid dissociation constant a2 derived from the acidic site represented by A ₂₂ H is greater than the acid dissociation constant a1 derived from the acidic site represented by HA _21. The preferred values of the acid dissociation constant a1 and the acid dissociation constant a2 are as described above.

In the above general formula (IIa), M ₂₁ ⁺ , M ₂₂ ⁺ , A ₂₁ ⁻ and A ₂₂ ⁻ have the same meanings as M ₁₁ ⁺ , M ₁₂ ⁺ , A ₁₁ ⁻ and A ₁₂ ⁻ in the above general formula (Ia), respectively, and the preferred embodiments are also the same.
In the above general formula (IIa), n1 M ₂₁ ⁺ groups and n1 A ₂₁ ⁺ groups each represent the same group.

In the above general formula (IIa), the (n1+n2)-valent organic group represented by _L2 is not particularly limited, and examples thereof include the groups represented by the following (A1) and (A2). In the following (A1) and (A2), at least two of the * marks represent the bonding positions ^with _A21- , and at least one of the * marks represents the bonding position ^with _A22- .

In the above (A1) and (A2), T ¹ represents a trivalent hydrocarbon ring group or a trivalent heterocyclic group, and T ² represents a carbon atom, a tetravalent hydrocarbon ring group, or a tetravalent heterocyclic group.

The hydrocarbon ring group may be an aromatic hydrocarbon ring group or an aliphatic hydrocarbon ring group. The hydrocarbon ring group preferably contains 6 to 18 carbon atoms, and more preferably 6 to 14 carbon atoms.
The heterocyclic group may be an aromatic heterocyclic group or an aliphatic heterocyclic group. The heterocyclic ring is preferably a 5- to 10-membered ring having at least one N atom, O atom, S atom, or Se atom in the ring structure, more preferably a 5- to 7-membered ring, and even more preferably a 5- or 6-membered ring.

In the above (A1) and (A2), L ²¹ and L ²² each independently represent a single bond or a divalent linking group.
The divalent linking group represented by L ²¹ and L ²² has the same meaning as the divalent linking group represented by L ₁ in the above general formula (Ia), and the preferred embodiments are also the same.
n1 represents an integer of 2 or more. The upper limit is not particularly limited, but is, for example, 6 or less, preferably 4 or less, and more preferably 3 or less.
n2 represents an integer of 1 or more. There is no particular upper limit to the number, but it is, for example, 3 or less, and preferably 2 or less.

(Compound (III))
Next, compound (III) will be described.
Compound (III): a compound having two or more of the structural moieties X and the following structural moiety Z, which generates an acid containing two or more of the first acidic moieties derived from the structural moiety X and the structural moiety Z upon irradiation with actinic rays or radiation. Structural moiety Z: a nonionic organic moiety capable of neutralizing an acid.

The nonionic organic moiety capable of neutralizing an acid in the structural moiety Z is not particularly limited, and is preferably, for example, an organic moiety containing a functional group having an electron or a group capable of electrostatically interacting with a proton.
Examples of functional groups having a group or electrons capable of electrostatically interacting with a proton include functional groups having a macrocyclic structure such as cyclic polyether, or functional groups having a nitrogen atom having an unshared electron pair that does not contribute to π conjugation. The nitrogen atom having an unshared electron pair that does not contribute to π conjugation is, for example, a nitrogen atom having a partial structure shown in the following formula:

Examples of partial structures of functional groups having groups or electrons that can electrostatically interact with protons include crown ether structures, azacrown ether structures, primary to tertiary amine structures, pyridine structures, imidazole structures, and pyrazine structures, among which primary to tertiary amine structures are preferred.

In the compound PIII obtained by replacing the cationic moiety M ₁ ⁺ in the structural moiety X in the compound (III) with H ⁺ , the acid dissociation constant a1 derived from the acidic moiety represented by HA ₁ obtained by replacing the cationic moiety M ₁ ⁺ in the structural moiety X with H ⁺ is preferably 2.0 or less, more preferably 0.5 or less, and even more preferably -0.1 or less, in terms of better LWR performance of the formed pattern. The lower limit of the acid dissociation constant a1 is preferably -15.0 or more.
In addition, when the compound PIII has a plurality of acid dissociation constants derived from the acidic site represented by _HA1 obtained by replacing the cationic site M ₁ ⁺ in the structural site X with H ⁺ , the smallest one is regarded as the acid dissociation constant a1.
That is, when compound (III) is, for example, a compound that generates an acid having two of the first acidic sites derived from the structural site X and the structural site Z, compound PIII corresponds to a "compound having two HA _1s ". When the acid dissociation constant of this compound PIII is calculated, the pKa when compound PIII becomes a "compound having one A ₁ ^- and one HA ₁ " is the acid dissociation constant a1. That is, when compound PIII has a plurality of acid dissociation constants derived from the acidic site represented by HA ₁ obtained by replacing the cationic site M ₁ ⁺ in the structural site X with H ⁺ , the smallest value is regarded as the acid dissociation constant a1.
In addition, compound PIII obtained by replacing the cationic moiety M ₁ ⁺ in the structural moiety X in compound (III) with H ⁺ corresponds to, for example, HA ₃₁ -L ₃ -N(R ^2X )-L ₄ -A ₃₁ H when compound (III) is a compound represented by compound (IIIa) described later.

Compound (III) is not particularly limited, but examples thereof include compounds represented by the following general formula (IIIa):

In general formula (IIIa), "M ₃₁ ⁺ A ₃₁ ^- " corresponds to the structural moiety X. When irradiated with actinic rays or radiation, compound (IIIa) generates an acid represented by HA ₃₁ -L ₃ -N(R ^2X )-L ₄ -A ₃₁ H. In other words, "M ₃₁ ⁺ A ₃₁ ^- " forms a first acidic moiety represented by HA ₃₁ .

In formula (IIIa), M ₃₁ ⁺ represents an organic cation.
A ₃₁ ^- represents an anionic functional group.
_L3 and _L4 each independently represent a divalent linking group.
^R2X represents a monovalent substituent.

In the above general formula (IIIa), M ₃₁ ⁺ and A ₃₁ ⁻ have the same meanings as M ₁₁ ⁺ and A ₁₁ ⁻ in the above general formula (Ia), respectively, and the preferred embodiments are also the same.
In the above general formula (IIIa), _L3 and _L4 each have the same meaning as _L1 in the above general formula (Ia), and the preferred embodiments are also the same.
In the above general formula (IIIa), the two M ₃₁ ⁺ 's and the two A ₃₁ ^-'s each represent the same group.

In general formula (IIIa), the monovalent substituent represented by R ^2X is not particularly limited and examples thereof include an alkyl group (preferably having ₁ to 10 carbon atoms, which may be linear or branched), a cycloalkyl group (preferably having 3 to 15 carbon atoms), or an alkenyl group (preferably having 2 to 6 carbon atoms), in which -CH ₂ - may be substituted with one or a combination of two or more selected from the group consisting of -CO-, -NH-, -O-, -S-, -SO-, and -SO 2 -.
The alkylene group, the cycloalkylene group, and the alkenylene group may be substituted with a substituent.

The molecular weight of the compounds represented by the above compounds (I) to (III) is preferably 300 to 3,000, more preferably 500 to 2,000, and even more preferably 700 to 1,500.

Preferred examples of compounds represented by the above compounds (I) to (III) are shown below.

<Photoacid Generator C>
The resist composition may contain another photoacid generator (photoacid generator C).

As the photoacid generator C, known compounds that generate an acid upon irradiation with actinic rays or radiation can be appropriately selected and used, either alone or as a mixture thereof. For example, known compounds disclosed in paragraphs [0125] to [0319] of US Patent Application Publication No. 2016/0070167 A1, paragraphs [0086] to [0094] of US Patent Application Publication No. 2015/0004544 A1, paragraphs [0323] to [0402] of US Patent Application Publication No. 2016/0237190 A1, and paragraphs [0074] to [0122] and [0137] to [0146] of JP 2018-155788 A can be suitably used as the photoacid generator C.

As the photoacid generator C, for example, a compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2) are also preferred.
The compound represented by the general formula (1) and the compound represented by the following general formula (2) will be described below.

(Compound represented by general formula (1))

In formula (1), M ₃ ⁺ represents an organic cation, and A ₃ ^- represents an anionic functional group.
R _a represents a hydrogen atom or a monovalent organic group. L _a represents a single bond or a divalent linking group.

The organic cation represented by M ₃ ⁺ has the same meaning as M ₁₁ ⁺ in compound (Ia), and the preferred embodiments are also the same.
The anionic functional group represented by A ₃ ^- is not particularly limited, but may be, for example, any of the groups represented by the following general formulae (C-1) to (C-7).

In formula (C-1), ^R represents a substituent.
R ^X1 is preferably a linear, branched, or cyclic alkyl group.
The alkyl group preferably has 1 to 15 carbon atoms, and more preferably has 1 to 10 carbon atoms.
The alkyl group may have a substituent. The substituent is preferably a fluorine atom or a cyano group. When the alkyl group has a fluorine atom as a substituent, it may be a perfluoroalkyl group.

In formulae (C-2) and (C-3), R ^X2 represents a hydrogen atom or a substituent other than a fluorine atom or a perfluoroalkyl group.
As the substituent other than a fluorine atom and a perfluoroalkyl group represented by R ^x2 , a linear, branched or cyclic alkyl group is preferable.
The alkyl group preferably has 1 to 15 carbon atoms, and more preferably has 1 to 10 carbon atoms.
The alkyl group may have a substituent other than a fluorine atom.

In formula (C-3), R ^{1 XF1} represents a fluorine atom or a perfluoroalkyl group.
The perfluoroalkyl group represented by R ^{2 XF1} preferably has 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 6 carbon atoms.

In formula (C-5), R ^X3 represents a substituent other than a fluorine atom.
The substituent other than a fluorine atom represented by ^Rx2 is preferably a linear, branched or cyclic alkyl group.
The alkyl group preferably has 1 to 15 carbon atoms, and more preferably has 1 to 10 carbon atoms.

In general formulas (C-5) and (C-6), n represents an integer of 0 to 4. An integer of 1 to 4 is more preferable for n.

In formula (C-7), _Lc represents a linear, branched, or cyclic alkylene group, preferably having 1 to 15 carbon atoms, and more preferably having 1 to 10 carbon atoms.
The alkylene group may be substituted with a substituent (for example, a fluorine atom, etc.).

The divalent linking group represented by L _a is not particularly limited, and examples thereof include one or more groups selected from the group consisting of -CO-, -NH-, -O-, -S-, -SO-, -SO ₂ -, and an alkylene group (preferably having 1 to 10 carbon atoms, which may be linear or branched).
The alkylene group may be substituted with a substituent (for example, a fluorine atom, etc.).

The monovalent organic group represented by R _a is not particularly limited, and examples thereof include a fluoroalkyl group (preferably having 1 to 10 carbon atoms, more preferably having 1 to 6 carbon atoms) and an organic group containing a cyclic structure, and among these, a cyclic organic group is preferable.
Examples of the cyclic organic group include an alicyclic group, an aryl group, and a heterocyclic group.
The alicyclic group may be monocyclic or polycyclic. Examples of the monocyclic alicyclic group include monocyclic cycloalkyl groups such as cyclopentyl, cyclohexyl, and cyclooctyl. Examples of the polycyclic alicyclic group include polycyclic cycloalkyl groups such as norbornyl, tricyclodecanyl, tetracyclodecanyl, tetracyclododecanyl, and adamantyl. Among them, alicyclic groups having a bulky structure with 7 or more carbon atoms, such as norbornyl, tricyclodecanyl, tetracyclodecanyl, tetracyclododecanyl, and adamantyl, are preferred.
In addition, the carbon atom of the alicyclic group may be substituted with a carbonyl group.

The aryl group may be monocyclic or polycyclic and includes, for example, phenyl, naphthyl, phenanthryl, and anthryl groups.
The heterocyclic group may be monocyclic or polycyclic. The polycyclic group can suppress the diffusion of the acid more effectively. The heterocyclic group may have aromaticity or may not have aromaticity. Examples of the heterocyclic ring having aromaticity include a furan ring, a thiophene ring, a benzofuran ring, a benzothiophene ring, a dibenzofuran ring, a dibenzothiophene ring, and a pyridine ring. Examples of the heterocyclic ring not having aromaticity include a tetrahydropyran ring, a lactone ring, a sultone ring, and a decahydroisoquinoline ring. Examples of the lactone ring and the sultone ring include the lactone structure and the sultone structure exemplified in the resin described later. As the heterocyclic ring in the heterocyclic group, a furan ring, a thiophene ring, a pyridine ring, or a decahydroisoquinoline ring is particularly preferable.

The cyclic organic group may have a substituent. Examples of the substituent include an alkyl group (which may be either linear or branched, and preferably has 1 to 12 carbon atoms), a cycloalkyl group (which may be either a monocyclic, polycyclic, or spirocyclic group, and preferably has 3 to 20 carbon atoms), an aryl group (which preferably has 6 to 14 carbon atoms), a hydroxyl group, an alkoxy group, an ester group, an amide group, a urethane group, a ureido group, a thioether group, a sulfonamide group, and a sulfonate ester group. The carbon that constitutes the cyclic organic group (the carbon that contributes to the ring formation) may be a carbonyl carbon.

In terms of better LWR performance of the formed pattern, in compound Q represented by HA ₃ -La-Ra in which M ₃ ⁺ in the above general formula (1) is replaced by H ⁺ , the acid dissociation constant of the acidic site represented by HA ₃ is −2.0 or more, preferably −1.0 or more, and more preferably 0 or more. There is no particular upper limit to the acid dissociation constant, but it is, for example, 6.0 or less, and preferably 2.0 or less.

(Compound represented by general formula (2))

In the above general formula (2), M ₄ ⁺ represents a sulfur ion or an iodine ion.
m represents 1 or 2, and is 2 when M ₄ ⁺ is a sulfur ion, and is 1 when M 4 + is an iodine atom.
Each R _b independently represents an alkyl group or alkenyl group, an aryl group, or a heteroaryl group, which may contain a heteroatom. When m is 2, two R _b may be bonded to each other to form a ring.
_Lb represents a divalent linking group.
A ₄ ^- represents an anionic functional group.

The alkyl or alkenyl group which may contain a heteroatom represented by R _b is not particularly limited, and examples thereof include an alkyl group having 1 to 20 carbon atoms (preferably having 1 to 10 carbon atoms) in which -CH ₂ - may be substituted with a heteroatom, and an alkenyl group having 1 to 20 carbon atoms (preferably having 2 to 10 carbon atoms) in which -CH ₂ - may be substituted with a heteroatom, etc. Examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom.
The alkyl or alkenyl group which may contain a heteroatom and is represented by _Rb may be any of linear, branched, and cyclic.
The alkyl or alkenyl group which may contain a heteroatom represented by _Rb may have a substituent, for example, an aryl group (preferably having 6 to 14 carbon atoms), a hydroxyl group, an alkoxy group, an ester group, an amide group, a urethane group, a ureido group, a thioether group, a sulfonamide group, and a sulfonate ester group.

The aryl group represented by _Rb may be either monocyclic or polycyclic, and examples of the aryl group include a phenyl group, a naphthyl group, a phenanthryl group, and an anthryl group.
The heteroaryl group represented by _Rb may be monocyclic or polycyclic. The polycyclic group is more effective in suppressing the diffusion of acid. Examples of the aromatic heterocycle constituting the heteroaryl group include a furan ring, a thiophene ring, a benzofuran ring, a benzothiophene ring, a dibenzofuran ring, a dibenzothiophene ring, and a pyridine ring.

The aryl group and heteroaryl group represented by _Rb may have a substituent. Examples of the substituent include an alkyl group (which may be either linear or branched, and preferably has 1 to 12 carbon atoms), a cycloalkyl group (which may be either a monocyclic, polycyclic, or spirocyclic ring, and preferably has 3 to 20 carbon atoms), an aryl group (which preferably has 6 to 14 carbon atoms), a hydroxyl group, an alkoxy group, an ester group, an amide group, a urethane group, a ureido group, a thioether group, a sulfonamide group, and a sulfonate ester group.

The divalent linking group represented by _Lb is not particularly limited, and examples thereof include one or more groups selected from the group consisting of -CO-, -NH-, -O-, -S-, -SO-, -SO ₂ -, an alkylene group (preferably having 1 to 10 carbon atoms, which may be linear or branched), and an arylene group (preferably having 6 to 10 carbon atoms), or a combination of two or more groups selected from the group consisting of these.
The alkylene group and arylene group may be substituted with a substituent (for example, a fluorine atom, etc.).

The anionic functional group represented by A ₄ ^- has the same meaning as the anionic functional group represented by A ₃ ^- described above, and the preferred embodiments are also the same.

In terms of better LWR performance of the formed pattern, in compound R represented by HA ₄ -L _b -M ₄ ⁺ -(R _b ) _m in which A ₄ ^- in the above general formula (2) is replaced with HA ₄ , the acid dissociation constant of the acidic site represented by HA ₄ is -2.0 or more, preferably -1.0 or more, and more preferably 0 or more. There is no particular upper limit to the acid dissociation constant, but it is, for example, 6.0 or less, and preferably 2.0 or less.

The molecular weight of the compound represented by the above general formula (1) and the compound represented by the above general formula (2) is preferably 300 to 3,000, more preferably 500 to 2,000, and even more preferably 700 to 1,500.

Preferred examples of compounds represented by general formulas (1) and (2) are given below.

[Acid-decomposable resin (resin (A))]
The resist composition of the present invention contains a resin that decomposes under the action of an acid to increase its polarity (hereinafter, also referred to as an "acid-decomposable resin" or "resin (A)").
That is, in the pattern formation method of the present invention, typically, when an alkaline developer is used as the developer, a positive pattern is preferably formed, and when an organic developer is used as the developer, a negative pattern is preferably formed.
The resin (A) usually contains a group that decomposes under the action of an acid to increase its polarity (hereinafter also referred to as an "acid-decomposable group"), and preferably contains a repeating unit having an acid-decomposable group.

<Repeating Unit Having Acid-Decomposable Group>
The acid decomposable group refers to a group that decomposes under the action of an acid to generate a polar group. The acid decomposable group preferably has a structure in which a polar group is protected by a leaving group that is removed under the action of an acid. That is, the resin (A) has a repeating unit that decomposes under the action of an acid to generate a polar group. The resin having this repeating unit has an increased polarity under the action of an acid, and its solubility in an alkaline developer increases, and its solubility in an organic solvent decreases.
The polar group is preferably an alkali-soluble group, and examples thereof include acidic groups such as a carboxyl group, a phenolic hydroxyl group, a fluorinated alcohol group, a sulfonic acid group, a phosphate group, a sulfonamide group, a sulfonylimide group, an (alkylsulfonyl)(alkylcarbonyl)methylene group, an (alkylsulfonyl)(alkylcarbonyl)imide group, a bis(alkylcarbonyl)methylene group, a bis(alkylcarbonyl)imide group, a bis(alkylsulfonyl)methylene group, a bis(alkylsulfonyl)imide group, a tris(alkylcarbonyl)methylene group, and a tris(alkylsulfonyl)methylene group, as well as an alcoholic hydroxyl group.
Among these, the polar group is preferably a carboxyl group, a phenolic hydroxyl group, a fluorinated alcohol group (preferably a hexafluoroisopropanol group), or a sulfonic acid group.

Examples of the leaving group which is eliminated by the action of an acid include groups represented by the formulae (Y1) to (Y4).
Formula (Y1): -C(Rx ₁ )(Rx ₂ )(Rx ₃ )
Formula (Y2): -C(=O)OC( _Rx1 )( _Rx2 )( _Rx3 )
Formula (Y3): -C(R ₃₆ )(R ₃₇ )(OR ₃₈ )
Formula (Y4): -C(Rn)(H)(Ar)

In formula (Y1) and formula (Y2), Rx ₁ to Rx ₃ each independently represent an alkyl group (linear or branched), a cycloalkyl group (monocyclic or polycyclic), an alkenyl group (linear or branched), or an aryl group (monocyclic or polycyclic). When all of Rx ₁ to Rx ₃ are alkyl groups (linear or branched), it is preferable that at least two of Rx ₁ to Rx ₃ are methyl groups.
In particular, it is preferable that Rx ₁ to Rx ₃ each independently represent a linear or branched alkyl group, and it is more preferable that Rx ₁ to Rx ₃ each independently represent a linear alkyl group.
Two of Rx ₁ to Rx ₃ may be bonded to form a monocycle or polycycle.
The alkyl group of Rx ₁ to Rx ₃ is preferably an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a t-butyl group.
The cycloalkyl groups of Rx ₁ to Rx ₃ are preferably monocyclic cycloalkyl groups such as a cyclopentyl group and a cyclohexyl group, and polycyclic cycloalkyl groups such as a norbornyl group, a tetracyclodecanyl group, a tetracyclododecanyl group, and an adamantyl group.
The aryl group of Rx ₁ to Rx ₃ is preferably an aryl group having 6 to 10 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, and an anthryl group.
The alkenyl group of Rx ₁ to Rx ₃ is preferably a vinyl group.
The ring formed by combining two of Rx ₁ to Rx ₃ is preferably a cycloalkyl group. The cycloalkyl group formed by combining two of Rx ₁ to Rx ₃ is preferably a monocyclic cycloalkyl group such as a cyclopentyl group or a cyclohexyl group, or a polycyclic cycloalkyl group such as a norbornyl group, a tetracyclodecanyl group, a tetracyclododecanyl group, or an adamantyl group, and more preferably a monocyclic cycloalkyl group having 5 to 6 carbon atoms.
In the cycloalkyl group formed by combining two of _Rx1 to _Rx3 , for example, one of the methylene groups constituting the ring may be replaced with a heteroatom such as an oxygen atom, a group having a heteroatom such as a carbonyl group, or a vinylidene group. Furthermore, in these cycloalkyl groups, one or more of the ethylene groups constituting the cycloalkane ring may be replaced with a vinylene group.
may be substituted.
In the group represented by formula (Y1) or formula (Y2), for example, it is preferable that _Rx1 is a methyl group or an ethyl group, and _Rx2 and _Rx3 are bonded to form the above-mentioned cycloalkyl group.

In formula (Y3), R ₃₆ to R ₃₈ each independently represent a hydrogen atom or a monovalent organic group. R ₃₇ and R ₃₈ may be bonded to each other to form a ring. Examples of the monovalent organic group include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and an alkenyl group. It is also preferable that R ₃₆ is a hydrogen atom.
The alkyl group, cycloalkyl group, aryl group, and aralkyl group may contain a heteroatom such as an oxygen atom and/or a group having a heteroatom such as a carbonyl group. For example, the alkyl group, cycloalkyl group, aryl group, and aralkyl group may have one or more methylene groups replaced with a heteroatom such as an oxygen atom and/or a group having a heteroatom such as a carbonyl group.
In addition, R ₃₈ may be bonded to another substituent in the main chain of the repeating unit to form a ring. The group formed by bonding R ₃₈ to another substituent in the main chain of the repeating unit is preferably an alkylene group such as a methylene group.

As formula (Y3), a group represented by the following formula (Y3-1) is preferred.

Here, L ₁ and L ₂ each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or a group formed by combining these groups (for example, a group formed by combining an alkyl group with an aryl group).
M represents a single bond or a divalent linking group.
Q represents an alkyl group which may contain a heteroatom, a cycloalkyl group which may contain a heteroatom, an aryl group which may contain a heteroatom, an amino group, an ammonium group, a mercapto group, a cyano group, an aldehyde group, or a group combining these (for example, a group combining an alkyl group and a cycloalkyl group).
The alkyl and cycloalkyl groups may, for example, have one of the methylene groups replaced with a heteroatom such as an oxygen atom or a group containing a heteroatom such as a carbonyl group.
It is preferable that one of _L1 and _L2 is a hydrogen atom, and the other is an alkyl group, a cycloalkyl group, an aryl group, or a group formed by combining an alkylene group and an aryl group.
At least two of Q, M and _L1 may be bonded to form a ring (preferably a 5- or 6-membered ring).
From the viewpoint of miniaturization of the pattern, _L2 is preferably a secondary or tertiary alkyl group, and more preferably a tertiary alkyl group. Examples of the secondary alkyl group include an isopropyl group, a cyclohexyl group, and a norbornyl group, and examples of the tertiary alkyl group include a tert-butyl group and an adamantane group. In these embodiments, Tg (glass transition temperature) and activation energy are high, so that in addition to ensuring the film strength, fogging can be suppressed.

In formula (Y4), Ar represents an aromatic ring group. Rn represents an alkyl group, a cycloalkyl group, or an aryl group. Rn and Ar may be bonded to each other to form a non-aromatic ring. Ar is more preferably an aryl group.

In terms of excellent acid decomposition properties of the repeating unit, when a non-aromatic ring is directly bonded to a polar group (or a residue thereof) in a leaving group protecting a polar group, it is also preferable that a ring atom in the non-aromatic ring adjacent to the ring atom directly bonded to the polar group (or a residue thereof) does not have a halogen atom such as a fluorine atom as a substituent.

Other examples of leaving groups that are eliminated by the action of an acid include a 2-cyclopentenyl group having a substituent (such as an alkyl group), such as a 3-methyl-2-cyclopentenyl group, and a cyclohexyl group having a substituent (such as an alkyl group), such as a 1,1,4,4-tetramethylcyclohexyl group.

As a repeating unit having an acid-decomposable group, a repeating unit represented by formula (A) is also preferred.

_L1 represents a divalent linking group which may have a fluorine atom or an iodine atom, _R1 represents a hydrogen atom, a fluorine atom, an iodine atom, an alkyl group which may have a fluorine atom or an iodine atom, or an aryl group which may have a fluorine atom or an iodine atom, and _R2 represents a leaving group which is eliminated by the action of an acid and which may have a fluorine atom or an iodine atom, provided that at least one of _L1 , _R1 , and _R2 has a fluorine atom or an iodine atom.
_L1 represents a divalent linking group which may have a fluorine atom or an iodine atom. Examples of the divalent linking group which may have a fluorine atom or an iodine atom include -CO-, -O-, -S-, -SO-, -SO ₂ -, a hydrocarbon group which may have a fluorine atom or an iodine atom (e.g., an alkylene group, a cycloalkylene group, an alkenylene group, an arylene group, etc.), and linking groups in which a plurality of these are linked together. Among these, -CO- or -arylene group-alkylene group having a fluorine atom or an iodine atom- is preferred as _L1 .
The arylene group is preferably a phenylene group.
The alkylene group may be linear or branched. The number of carbon atoms in the alkylene group is not particularly limited, but is preferably 1 to 10, and more preferably 1 to 3.
The total number of fluorine atoms and iodine atoms contained in the alkylene group having a fluorine atom or an iodine atom is not particularly limited, but is preferably 2 or more, more preferably 2 to 10, and even more preferably 3 to 6.

R ₁ represents a hydrogen atom, a fluorine atom, an iodine atom, an alkyl group which may have a fluorine atom or an iodine atom, or an aryl group which may have a fluorine atom or an iodine atom.
The alkyl group may be linear or branched. The number of carbon atoms in the alkyl group is not particularly limited, but is preferably 1 to 10, and more preferably 1 to 3.
The total number of fluorine atoms and iodine atoms contained in the alkyl group having a fluorine atom or an iodine atom is not particularly limited, but is preferably 1 or more, more preferably 1 to 5, and even more preferably 1 to 3.
The alkyl group may contain a heteroatom other than a halogen atom, such as an oxygen atom.

_R2 represents a leaving group which is eliminated by the action of an acid and which may have a fluorine atom or an iodine atom.
Among them, examples of the leaving group include groups represented by formulae (Z1) to (Z4).
Formula (Z1): -C( _Rx11 )( _Rx12 )( _Rx13 ) Formula (Z2): -C(=O)OC( _Rx11 )( _Rx12 )( _Rx13 ) Formula (Z3): -C( _R136 )( _R137 )( _OR138 ) Formula (Z4): -C( _Rn1 )(H)( _Ar1 )

In formula (Z1) and (Z2), _Rx11 to _Rx13 each independently represent an alkyl group (linear or branched) which may have a fluorine atom or an iodine atom, a cycloalkyl group (monocyclic or polycyclic) which may have a fluorine atom or an iodine atom, an alkenyl group (linear or branched) which may have a fluorine atom or an iodine atom, or an aryl group (monocyclic or polycyclic) which may have a fluorine atom or an iodine atom. Note that when all of _Rx11 to _Rx13 are alkyl groups (linear or branched), it is preferable that at least two of _Rx11 to _Rx13 are methyl groups.
_Rx11 to _Rx13 are the same as Rx1 to _Rx3 in (Y1) and (Y2) described above, except that they may have a fluorine atom or an iodine atom, and the definitions and preferred ranges of an alkyl group, a cycloalkyl group, an alkenyl group, and an aryl group are the same as those of _Rx11 to Rx3 in (Y1) and (Y2).

In formula (Z3), R ₁₃₆ to R ₁₃₈ each independently represent a hydrogen atom, or a monovalent organic group which may have a fluorine atom or an iodine atom. R ₁₃₇ and R ₁₃₈ may be bonded to each other to form a ring. Examples of the monovalent organic group which may have a fluorine atom or an iodine atom include an alkyl group which may have a fluorine atom or an iodine atom, a cycloalkyl group which may have a fluorine atom or an iodine atom, an aryl group which may have a fluorine atom or an iodine atom, an aralkyl group which may have a fluorine atom or an iodine atom, and a group which combines these (for example, a group which combines an alkyl group and a cycloalkyl group).
The alkyl group, cycloalkyl group, aryl group, and aralkyl group may contain a heteroatom such as an oxygen atom in addition to a fluorine atom and an iodine atom. That is, the alkyl group, cycloalkyl group, aryl group, and aralkyl group may have, for example, one methylene group replaced with a heteroatom such as an oxygen atom or a group having a heteroatom such as a carbonyl group.
R ₁₃₈ may be bonded to another substituent in the main chain of the repeating unit to form a ring. In this case, the group formed by bonding R ₁₃₈ to another substituent in the main chain of the repeating unit is preferably an alkylene group such as a methylene group.

As formula (Z3), a group represented by the following formula (Z3-1) is preferred.

Here, _L11 and _L12 each independently represent a hydrogen atom; an alkyl group which may have a heteroatom selected from the group consisting of a fluorine atom, an iodine atom, and an oxygen atom; a cycloalkyl group which may have a heteroatom selected from the group consisting of a fluorine atom, an iodine atom, and an oxygen atom; an aryl group which may have a heteroatom selected from the group consisting of a fluorine atom, an iodine atom, and an oxygen atom; or a group combining these (for example, a group combining an alkyl group and a cycloalkyl group which may have a heteroatom selected from the group consisting of a fluorine atom, an iodine atom, and an oxygen atom).
M ₁ represents a single bond or a divalent linking group.
_Q1 represents an alkyl group which may have a heteroatom selected from the group consisting of a fluorine atom, an iodine atom, and an oxygen atom; a cycloalkyl group which may have a heteroatom selected from the group consisting of a fluorine atom, an iodine atom, and an oxygen atom; an aryl group which is selected from the group consisting of a fluorine atom, an iodine atom, and an oxygen atom; an amino group; an ammonium group; a mercapto group; a cyano group; an aldehyde group; or a group combining these (for example, a group combining an alkyl group and a cycloalkyl group which may have a heteroatom selected from the group consisting of a fluorine atom, an iodine atom, and an oxygen atom).

In formula (Z4), Ar ₁ represents an aromatic ring group which may have a fluorine atom or an iodine atom. Rn ₁ represents an alkyl group which may have a fluorine atom or an iodine atom, a cycloalkyl group which may have a fluorine atom or an iodine atom, or an aryl group which may have a fluorine atom or an iodine atom. Rn ₁ and Ar ₁ may be bonded to each other to form a non-aromatic ring.

As a repeating unit having an acid-decomposable group, a repeating unit represented by general formula (AI) is also preferred.

In general formula (AI),
_Xa1 represents a hydrogen atom or an alkyl group which may have a substituent.
T represents a single bond or a divalent linking group.
_Rx1 to _Rx3 each independently represent an alkyl group (linear or branched), a cycloalkyl group (monocyclic or polycyclic), an alkenyl group (linear or branched), or an aryl group (monocyclic or polycyclic). However, when all of _Rx1 to _Rx3 are alkyl groups (linear or branched), it is preferable that at least two of _Rx1 to _Rx3 are methyl groups.
Two of Rx ₁ to Rx ₃ may be bonded to form a monocyclic or polycyclic ring (eg, a monocyclic or polycyclic cycloalkyl group).

Examples of the alkyl group represented by Xa ₁ which may have a substituent include a methyl group or a group represented by -CH ₂ -R _{11. R 11} represents a halogen atom (such as a fluorine atom), a hydroxyl group or a monovalent organic group, and examples thereof include an alkyl group having 5 or less carbon atoms which may be substituted with a halogen atom, an acyl group having 5 or less carbon atoms which may be substituted with a halogen atom, and an alkoxy group having 5 or less carbon atoms which may be substituted with a halogen atom, with an alkyl group having 3 or less carbon atoms being preferred, and a methyl group being more preferred. Xa ₁ is preferably a hydrogen atom, a methyl group, a trifluoromethyl group, or a hydroxymethyl group.

Examples of the divalent linking group for T include an alkylene group, an aromatic ring group, a -COO-Rt- group, and a -O-Rt- group, in which Rt represents an alkylene group or a cycloalkylene group.
T is preferably a single bond or a -COO-Rt- group. When T represents a -COO-Rt- group, Rt is preferably an alkylene group having 1 to 5 carbon atoms, more preferably a -CH ₂ - group, a -(CH ₂ ) ₂ - group, or a -(CH ₂ ) ₃ - group.

The alkyl group of Rx ₁ to Rx ₃ is preferably an alkyl group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a t-butyl group.
The cycloalkyl groups of Rx ₁ to Rx ₃ are preferably monocyclic cycloalkyl groups such as a cyclopentyl group and a cyclohexyl group, or polycyclic cycloalkyl groups such as a norbornyl group, a tetracyclodecanyl group, a tetracyclododecanyl group, and an adamantyl group.
The aryl group of Rx ₁ to Rx ₃ is preferably an aryl group having 6 to 10 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, and an anthryl group.
The alkenyl group of Rx ₁ to Rx ₃ is preferably a vinyl group.
The cycloalkyl group formed by combining two of Rx ₁ to Rx ₃ is preferably a monocyclic cycloalkyl group such as a cyclopentyl group or a cyclohexyl group, and is further preferably a polycyclic cycloalkyl group such as a norbornyl group, a tetracyclodecanyl group, a tetracyclododecanyl group, an adamantyl group, etc. Among these, a monocyclic cycloalkyl group having 5 to 6 carbon atoms is preferred.
In the cycloalkyl group formed by combining two of _Rx1 to _Rx3 , for example, one of the methylene groups constituting the ring may be replaced with a heteroatom such as an oxygen atom, a group having a heteroatom such as a carbonyl group, or a vinylidene group. In addition, in these cycloalkyl groups, one or more of the ethylene groups constituting the cycloalkane ring may be replaced with a vinylene group.
In the repeating unit represented by formula (AI), for example, _Rx1 is preferably a methyl group or an ethyl group, and _Rx2 and _Rx3 are bonded to form the above-mentioned cycloalkyl group.

When each of the above groups has a substituent, examples of the substituent include an alkyl group (having 1 to 4 carbon atoms), a halogen atom, a hydroxyl group, an alkoxy group (having 1 to 4 carbon atoms), a carboxyl group, and an alkoxycarbonyl group (having 2 to 6 carbon atoms). The number of carbon atoms in the substituent is preferably 8 or less.

The repeating unit represented by general formula (AI) is preferably an acid-decomposable (meth)acrylic acid tertiary alkyl ester repeating unit (a repeating unit in which _Xa1 represents a hydrogen atom or a methyl group and T represents a single bond).

The content of the repeating units having an acid-decomposable group is preferably 15 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, based on the total repeating units in the resin (A). The upper limit is preferably 80 mol% or less, more preferably 70 mol% or less, and particularly preferably 60 mol% or less.

Specific examples of repeating units having an acid-decomposable group are shown below, but the present invention is not limited thereto. In the formula, _Xa1 is any one of H, CH ₃ , CF ₃ and CH ₂ OH, and Rxa and Rxb each represent a linear or branched alkyl group having 1 to 5 carbon atoms.

The resin (A) may contain repeating units other than the repeating units described above.
For example, resin (A) may contain at least one type of repeating unit selected from the group consisting of Group A below, and/or at least one type of repeating unit selected from the group consisting of Group B below.
Group A: A group consisting of the following repeating units (20) to (29).
(20) a repeating unit having an acid group, as described later; (21) a repeating unit having a fluorine atom or an iodine atom, as described later; (22) a repeating unit having a lactone group, a sultone group, or a carbonate group, as described later; (23) a repeating unit having a photoacid generating group, as described later; (24) a repeating unit represented by general formula (V-1) or the following general formula (V-2), as described later; (25) a repeating unit represented by formula (A), as described later; (26) a repeating unit represented by formula (B), as described later; (27) a repeating unit represented by formula (C), as described later; (28) a repeating unit represented by formula (D), as described later; (29) a repeating unit represented by formula (E), as described later. Group B: a group consisting of the following repeating units (30) to (32).
(30) A repeating unit having at least one group selected from a lactone group, a sultone group, a carbonate group, a hydroxyl group, a cyano group, and an alkali-soluble group, as described below. (31) A repeating unit having an alicyclic hydrocarbon structure and not exhibiting acid decomposability, as described below. (32) A repeating unit represented by general formula (III), as described below, which does not have either a hydroxyl group or a cyano group.

When the resist composition of the present invention is used as an actinic ray-sensitive or radiation-sensitive resin composition for EUV, the resin (A) preferably has at least one type of repeating unit selected from the group consisting of Group A above.
In addition, when the resist composition of the present invention is used as an actinic ray-sensitive or radiation-sensitive resin composition for EUV, it is preferable that the resin (A) contains at least one of a fluorine atom and an iodine atom. When the resin (A) contains both a fluorine atom and an iodine atom, the resin (A) may have one repeating unit containing both a fluorine atom and an iodine atom, or the resin (A) may contain two types of repeating units, a repeating unit containing a fluorine atom and a repeating unit containing an iodine atom.
Furthermore, when the resist composition of the present invention is used as an actinic ray-sensitive or radiation-sensitive resin composition for EUV, it is also preferable that the resin (A) has a repeating unit having an aromatic group.
When the resist composition of the present invention is used as an ArF actinic ray-sensitive or radiation-sensitive resin composition, the resin (A) preferably has at least one type of repeating unit selected from the group consisting of Group B above.
When the resist composition of the present invention is used as an ArF actinic ray-sensitive or radiation-sensitive resin composition, it is preferable that the resin (A) contains neither fluorine atoms nor silicon atoms.
Furthermore, when the resist composition of the present invention is used as an ArF actinic ray-sensitive or radiation-sensitive resin composition, it is preferable that the resin (A) does not have an aromatic group.

<Repeating Unit Having an Acid Group>
The resin (A) may have a repeating unit having an acid group.
The acid group is preferably an acid group having a pKa of 13 or less.
The acid group is preferably, for example, a carboxyl group, a phenolic hydroxyl group, a fluorinated alcohol group (preferably a hexafluoroisopropanol group), a sulfonic acid group, a sulfonamide group, or an isopropanol group.
In addition, in the above hexafluoroisopropanol group, one or more (preferably one or two) fluorine atoms may be substituted with a group other than a fluorine atom (such as an alkoxycarbonyl group). The thus formed -C( _CF3 )(OH) _-CF2- is also preferable as an acid group. In addition, one or more fluorine atoms may be substituted with a group other than a fluorine atom to form a ring containing -C( _CF3 )(OH) _-CF2- .
The repeating unit having an acid group is preferably a repeating unit different from the repeating unit having a structure in which a polar group is protected with a leaving group that is eliminated by the action of an acid described above, and the repeating unit having a lactone group, a sultone group, or a carbonate group described below.

The repeating unit having an acid group may have a fluorine atom or an iodine atom.

As a repeating unit having an acid group, a repeating unit represented by formula (B) is preferred.

_R3 represents a hydrogen atom or a monovalent organic group which may have a fluorine atom or an iodine atom.
The monovalent organic group which may have a fluorine atom or an iodine atom is preferably a group represented by -L ₄ -R _8. L ₄ represents a single bond or an ester group. R ₈ may be an alkyl group which may have a fluorine atom or an iodine atom, a cycloalkyl group which may have a fluorine atom or an iodine atom, an aryl group which may have a fluorine atom or an iodine atom, or a group which is a combination of these.

_R4 and _R5 each independently represent a hydrogen atom, a fluorine atom, an iodine atom, or an alkyl group which may have a fluorine atom or an iodine atom.

_L2 represents a single bond or an ester group.
_L3 represents an aromatic hydrocarbon ring group having a valence of (n+m+1) or an alicyclic hydrocarbon ring group having a valence of (n+m+1). Examples of the aromatic hydrocarbon ring group include a benzene ring group and a naphthalene ring group. Examples of the alicyclic hydrocarbon ring group include a monocyclic or polycyclic ring group, such as a cycloalkyl ring group.
_R6 represents a hydroxyl group or a fluorinated alcohol group (preferably a hexafluoroisopropanol group). When _R6 is a hydroxyl group, _L3 is preferably an aromatic hydrocarbon ring group having a valence of (n+m+1).
_R7 represents a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
m represents an integer of 1 or more, preferably an integer of 1 to 3, and more preferably an integer of 1 or 2.
n represents an integer of 0 or more, and is preferably an integer of 1 to 4.
Incidentally, (n+m+1) is preferably an integer of 1 to 5.

As a repeating unit having an acid group, a repeating unit represented by the following general formula (I) is also preferred.

In general formula (I),
R ₄₁ , R ₄₂ and R ₄₃ each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group or an alkoxycarbonyl group, provided that R ₄₂ may be bonded to Ar ₄ to form a ring, in which case R ₄₂ represents a single bond or an alkylene group.
X ₄ represents a single bond, —COO— or —CONR ₆₄ —, where R ₆₄ represents a hydrogen atom or an alkyl group.
_L4 represents a single bond or an alkylene group.
Ar ₄ represents an (n+1)-valent aromatic ring group, and when Ar 4 is bonded to R ₄₂ to form a ring, it represents an (n+2)-valent aromatic ring group.
n represents an integer of 1 to 5.

The alkyl group of R ₄₁ , R ₄₂ , and R ₄₃ in general formula (I) is preferably an alkyl group having 20 or less carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a hexyl group, a 2-ethylhexyl group, an octyl group, or a dodecyl group, more preferably an alkyl group having 8 or less carbon atoms, and even more preferably an alkyl group having 3 or less carbon atoms.

The cycloalkyl group of R ₄₁ , R ₄₂ , and R ₄₃ in the general formula (I) may be a monocyclic or polycyclic cycloalkyl group, and among them, a monocyclic cycloalkyl group having 3 to 8 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group, is preferred.
Examples of the halogen atom for R ₄₁ , R ₄₂ and R ₄₃ in formula (I) include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, with a fluorine atom being preferred.
As the alkyl group contained in the alkoxycarbonyl group of R ₄₁ , R ₄₂ and R ₄₃ in the general formula (I), the same as the alkyl group in the above R ₄₁ , R ₄₂ and R ₄₃ is preferable.

Preferred examples of the substituents in each of the above groups include alkyl groups, cycloalkyl groups, aryl groups, amino groups, amide groups, ureido groups, urethane groups, hydroxyl groups, carboxyl groups, halogen atoms, alkoxy groups, thioether groups, acyl groups, acyloxy groups, alkoxycarbonyl groups, cyano groups, and nitro groups. The number of carbon atoms in the substituents is preferably 8 or less.

Ar ₄ represents an aromatic ring group having a valence of (n+1). When n is 1, the divalent aromatic ring group is preferably an arylene group having 6 to 18 carbon atoms, such as a phenylene group, a tolylene group, a naphthylene group, or an anthracenylene group, or a divalent aromatic ring group containing a heterocycle, such as a thiophene ring, a furan ring, a pyrrole ring, a benzothiophene ring, a benzofuran ring, a benzopyrrole ring, a triazine ring, an imidazole ring, a benzimidazole ring, a triazole ring, a thiadiazole ring, or a thiazole ring. The aromatic ring group may have a substituent.

Specific examples of the (n+1)-valent aromatic ring group when n is an integer of 2 or more include groups obtained by removing any (n-1) hydrogen atoms from the above-mentioned specific examples of the divalent aromatic ring group.
The (n+1)-valent aromatic ring group may further have a substituent.

Examples of the substituent that the above-mentioned alkyl group, cycloalkyl group, alkoxycarbonyl group, alkylene group, and (n+1)-valent aromatic ring group may have include the alkyl groups listed as R ₄₁ , R ₄₂ , and R ₄₃ in general formula (I), alkoxy groups such as a methoxy group, an ethoxy group, a hydroxyethoxy group, a propoxy group, a hydroxypropoxy group, and a butoxy group; aryl groups such as a phenyl group; and the like.
Examples of the alkyl group for R ₆₄ in -CONR ₆₄ - (R ₆₄ represents a hydrogen atom or an alkyl group) represented by X ₄ include alkyl groups having 20 or less carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a hexyl group, a 2-ethylhexyl group, an octyl group, and a dodecyl group, and an alkyl group having 8 or less carbon atoms is preferred.
_X4 is preferably a single bond, --COO-- or --CONH--, and more preferably a single bond or --COO--.

The alkylene group in _L4 is preferably an alkylene group having 1 to 8 carbon atoms, such as a methylene group, an ethylene group, a propylene group, a butylene group, a hexylene group, or an octylene group.
Ar ₄ is preferably an aromatic ring group having 6 to 18 carbon atoms, more preferably a benzene ring group, a naphthalene ring group, or a biphenylene ring group.
The repeating unit represented by formula (I) preferably has a hydroxystyrene structure, i.e., _Ar4 is preferably a benzene ring group.

As the repeating unit represented by general formula (I), the repeating unit represented by the following general formula (1) is preferred.

In the general formula (1),
A represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, or a cyano group.
R represents a halogen atom, an alkyl group, a cycloalkyl group, an aryl group, an alkenyl group, an aralkyl group, an alkoxy group, an alkylcarbonyloxy group, an alkylsulfonyloxy group, an alkyloxycarbonyl group, or an aryloxycarbonyl group, and when there are a plurality of R, they may be the same or different. When there are a plurality of R, they may be combined together to form a ring. R is preferably a hydrogen atom.
a represents an integer of 1 to 3.
b represents an integer of 0 to (5-a).

The following are examples of repeating units having an acid group. In the formula, a represents 1 or 2.

Among the above repeating units, the repeating units specifically described below are preferred. In the formula, R represents a hydrogen atom or a methyl group, and a represents 2 or 3.

The content of the repeating units having an acid group is preferably 10 mol% or more, more preferably 15 mol% or more, based on the total repeating units in the resin (A). The upper limit is preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 60 mol% or less.

<Repeating Unit Having Fluorine Atom or Iodine Atom>
The resin (A) may have a repeating unit having a fluorine atom or an iodine atom in addition to the above-mentioned <repeating unit having an acid-decomposable group> and <repeating unit having an acid group>. The <repeating unit having a fluorine atom or an iodine atom> referred to here is preferably different from other types of repeating units belonging to Group A, such as the <repeating unit having a lactone group, a sultone group, or a carbonate group> and the <repeating unit having a photoacid generating group> described below.

As a repeating unit having a fluorine atom or an iodine atom, a repeating unit represented by formula (C) is preferred.

_L5 represents a single bond or an ester group.
R ₉ represents a hydrogen atom, or an alkyl group which may have a fluorine atom or an iodine atom.
R ₁₀ represents a hydrogen atom, an alkyl group which may have a fluorine atom or an iodine atom, a cycloalkyl group which may have a fluorine atom or an iodine atom, an aryl group which may have a fluorine atom or an iodine atom, or a group consisting of a combination thereof.

Examples of repeating units containing fluorine or iodine atoms are shown below.

The content of the repeating units having a fluorine atom or an iodine atom is preferably 0 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, based on the total repeating units in the resin (A), and the upper limit is preferably 50 mol% or less, more preferably 45 mol% or less, and even more preferably 40 mol% or less.
As described above, the repeating units having a fluorine atom or an iodine atom do not include <repeating units having an acid decomposable group> and <repeating units having an acid group>. Therefore, the content of the repeating units having a fluorine atom or an iodine atom also refers to the content of repeating units having a fluorine atom or an iodine atom excluding <repeating units having an acid decomposable group> and <repeating units having an acid group>.

The total content of repeating units containing at least one of a fluorine atom and an iodine atom in the repeating units of the resin (A) is preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 40 mol% or more, based on the total repeating units of the resin (A). The upper limit is not particularly limited, but is, for example, 100 mol% or less.
Examples of the repeating unit containing at least one of a fluorine atom and an iodine atom include a repeating unit having a fluorine atom or an iodine atom and an acid-decomposable group, a repeating unit having a fluorine atom or an iodine atom and an acid group, and a repeating unit having a fluorine atom or an iodine atom.

<Repeating Unit Having a Lactone Group, a Sultone Group, or a Carbonate Group>
Resin (A) may have a repeating unit having at least one selected from the group consisting of a lactone group, a sultone group, and a carbonate group (hereinafter, also collectively referred to as a "repeating unit having a lactone group, a sultone group, or a carbonate group").
It is also preferred that the repeating units having a lactone group, a sultone group, or a carbonate group do not have an acid group such as a hexafluoropropanol group.

The lactone group or sultone group may have a lactone structure or sultone structure. The lactone structure or sultone structure is preferably a 5- to 7-membered lactone structure or a 5- to 7-membered sultone structure. Among them, a 5- to 7-membered lactone structure having another ring structure condensed thereto in the form of a bicyclo structure or a spiro structure, or a 5- to 7-membered sultone structure having another ring structure condensed thereto in the form of a bicyclo structure or a spiro structure, is more preferred.
Resin (A) preferably has a repeating unit having a lactone structure represented by any of the following general formulas (LC1-1) to (LC1-21), or a lactone group or sultone group obtained by abstracting one or more hydrogen atoms from a ring member atom of a sultone structure represented by any of the following general formulas (SL1-1) to (SL1-3):
Furthermore, the lactone group or sultone group may be directly bonded to the main chain. For example, the ring atoms of the lactone group or sultone group may constitute the main chain of the resin (A).

The lactone structure or sultone structure portion may have a substituent (Rb ₂ ). Preferred substituents (Rb ₂ ) include an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 4 to 7 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an alkoxycarbonyl group having 1 to 8 carbon atoms, a carboxyl group, a halogen atom, a hydroxyl group, a cyano group, and an acid-decomposable group. n2 represents an integer of 0 to 4. When n2 is 2 or more, the multiple Rb _2s may be different from each other, and the multiple Rb _2s may be bonded to each other to form a ring.

Examples of repeating units having a group having a lactone structure represented by any of general formulas (LC1-1) to (LC1-21) or a sultone structure represented by any of general formulas (SL1-1) to (SL1-3) include repeating units represented by the following general formula (AI).

In formula (AI), Rb ₀ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms.
Preferred examples of the substituent that the alkyl group of _Rb0 may have include a hydroxyl group and a halogen atom.
Examples of the halogen atom of Rb ₀ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Rb ₀ is preferably a hydrogen atom or a methyl group.
Ab represents a single bond, an alkylene group, a divalent linking group having a monocyclic or polycyclic alicyclic hydrocarbon structure, an ether group, an ester group, a carbonyl group, a carboxyl group, or a divalent group combining these. Of these, a single bond or a linking group represented by -Ab ₁ -CO ₂ - is preferred. Ab ₁ represents a linear or branched alkylene group, or a monocyclic or polycyclic cycloalkylene group, and is preferably a methylene group, an ethylene group, a cyclohexylene group, an adamantylene group, or a norbornylene group.
V represents a group obtained by removing one hydrogen atom from a ring member atom of a lactone structure represented by any of general formulas (LC1-1) to (LC1-21), or a group obtained by removing one hydrogen atom from a ring member atom of a sultone structure represented by any of general formulas (SL1-1) to (SL1-3).

When optical isomers are present in the repeating unit having a lactone group or a sultone group, any of the optical isomers may be used. In addition, one optical isomer may be used alone, or multiple optical isomers may be used in combination. When one optical isomer is mainly used, the optical purity (ee) is preferably 90 or more, and more preferably 95 or more.

The carbonate group is preferably a cyclic carbonate group.
The repeating unit having a cyclic carbonate group is preferably a repeating unit represented by the following formula (A-1).

In formula (A-1), R _A ¹ represents a hydrogen atom, a halogen atom, or a monovalent organic group (preferably a methyl group).
n represents an integer of 0 or more.
R _A ² represents a substituent. When n is 2 or more, a plurality of R _A ² may be the same or different.
A represents a single bond or a divalent linking group. The divalent linking group is preferably an alkylene group, a divalent linking group having a monocyclic or polycyclic alicyclic hydrocarbon structure, an ether group, an ester group, a carbonyl group, a carboxyl group, or a divalent group formed by combining these groups.
Z represents an atomic group which forms a monocyclic or polycyclic ring together with the group represented by --O--CO--O-- in the formula.

Examples of repeating units having a lactone group, a sultone group, or a carbonate group are shown below.

The content of repeating units having a lactone group, a sultone group, or a carbonate group is preferably 1 mol% or more, more preferably 10 mol% or more, based on the total repeating units in resin (A). The upper limit is preferably 85 mol% or less, more preferably 80 mol% or less, even more preferably 70 mol% or less, and particularly preferably 60 mol% or less.

<Repeating Unit Having Photoacid Generating Group>
The resin (A) may contain, as a repeating unit other than those described above, a repeating unit having a group that generates an acid upon irradiation with actinic rays or radiation (hereinafter also referred to as a "photoacid generating group").
In this case, the repeating unit having the photoacid generating group can be considered to correspond to a compound (also called a "photoacid generator") that generates an acid when exposed to actinic rays or radiation, which will be described later.
An example of such a repeating unit is a repeating unit represented by the following general formula (4).

R ⁴¹ represents a hydrogen atom or a methyl group. L ⁴¹ represents a single bond or a divalent linking group. L ⁴² represents a divalent linking group. R ⁴⁰ represents a structural moiety that is decomposed by irradiation with actinic rays or radiation to generate an acid in a side chain.

Examples of repeating units having a photoacid generating group are shown below.

Other examples of the repeating units represented by general formula (4) include the repeating units described in paragraphs [0094] to [0105] of JP 2014-041327 A.

The content of the repeating unit having a photoacid generating group is preferably 1 mol% or more, more preferably 5 mol% or more, based on the total repeating units in the resin (A). The upper limit is preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less.

<Repeating units represented by general formula (V-1) or the following general formula (V-2)>
The resin (A) may have a repeating unit represented by the following general formula (V-1) or the following general formula (V-2).
The repeating units represented by the following general formula (V-1) and the following general formula (V-2) are preferably repeating units different from the repeating units described above.

In the formula,
_R6 and _R7 each independently represent a hydrogen atom, a hydroxyl group, an alkyl group, an alkoxy group, an acyloxy group, a cyano group, a nitro group, an amino group, a halogen atom, an ester group (-OCOR or -COOR: R is an alkyl group or a fluorinated alkyl group having 1 to 6 carbon atoms), or a carboxyl group. As the alkyl group, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms is preferable.
_n3 represents an integer of 0 to 6.
_n4 represents an integer of 0 to 4.
^X4 is a methylene group, an oxygen atom, or a sulfur atom.
Examples of the repeating units represented by formula (V-1) or (V-2) are shown below.

<Repeating units for reducing main chain mobility>
Resin (A) preferably has a high glass transition temperature (Tg) from the viewpoint of suppressing excessive diffusion of generated acid or pattern collapse during development. Tg is preferably higher than 90° C., more preferably higher than 100° C., even more preferably higher than 110° C., and particularly preferably higher than 125° C. In addition, since an excessively high Tg leads to a decrease in the dissolution rate in a developer, Tg is preferably 400° C. or lower, more preferably 350° C. or lower.
In this specification, the glass transition temperature (Tg) of a polymer such as resin (A) is calculated by the following method. First, the Tg of a homopolymer consisting of only each repeating unit contained in the polymer is calculated by the Bicerano method. Hereinafter, the calculated Tg is referred to as the "Tg of the repeating unit". Next, the mass ratio (%) of each repeating unit to the total repeating units in the polymer is calculated. Next, the Tg at each mass ratio is calculated using the Fox formula (described in Materials Letters 62 (2008) 3152, etc.), and these are summed up to obtain the Tg (°C) of the polymer.
The Bicerano method is described in Prediction of Polymer Properties, Marcel Dekker Inc., New York (1993), etc. The calculation of Tg by the Bicerano method can be performed using polymer property estimation software MDL Polymer (MDL Information Systems, Inc.).

In order to increase the Tg of the resin (A) (preferably to make the Tg exceed 90° C.), it is preferable to reduce the mobility of the main chain of the resin (A). Methods for reducing the mobility of the main chain of the resin (A) include the following methods (a) to (e).
(a) introduction of a bulky substituent into the main chain; (b) introduction of a plurality of substituents into the main chain; (c) introduction of a substituent inducing an interaction between resins (A) in the vicinity of the main chain; (d) formation of a main chain with a cyclic structure; (e) linking of a cyclic structure to the main chain. Note that resin (A) preferably has a repeating unit showing a homopolymer Tg of 130° C. or higher.
The type of repeating unit exhibiting a homopolymer Tg of 130° C. or higher is not particularly limited, and may be any repeating unit exhibiting a homopolymer Tg of 130° C. or higher as calculated by the Bicerano method. Depending on the type of functional group in the repeating units represented by formulae (A) to (E) described below, the repeating unit may be one exhibiting a homopolymer Tg of 130° C. or higher.

(Repeating unit represented by formula (A))
One example of a specific means for achieving the above (a) is a method in which a repeating unit represented by formula (A) is introduced into resin (A).

In formula (A), _R represents a group having a polycyclic structure. _Rx represents a hydrogen atom, a methyl group, or an ethyl group. The group having a polycyclic structure is a group having a plurality of ring structures, and the plurality of ring structures may or may not be condensed.
Specific examples of the repeating unit represented by formula (A) include the following repeating units.

In the above formula, R represents a hydrogen atom, a methyl group, or an ethyl group.
Ra represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an acyloxy group, a cyano group, a nitro group, an amino group, a halogen atom, an ester group (-OCOR''' or -COOR''': R''' is an alkyl group or a fluorinated alkyl group having 1 to 20 carbon atoms), or a carboxyl group. The alkyl group, the cycloalkyl group, the aryl group, the aralkyl group, and the alkenyl group may each have a substituent. In addition, a hydrogen atom bonded to a carbon atom in the group represented by Ra may be substituted with a fluorine atom or an iodine atom.
Furthermore, R' and R" each independently represent an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an acyloxy group, a cyano group, a nitro group, an amino group, a halogen atom, an ester group (-OCOR"' or -COOR"': R"' is an alkyl group or a fluorinated alkyl group having 1 to 20 carbon atoms), or a carboxyl group. The alkyl group, the cycloalkyl group, the aryl group, the aralkyl group, and the alkenyl group may each have a substituent. Furthermore, a hydrogen atom bonded to a carbon atom in the group represented by R' and R" may be substituted with a fluorine atom or an iodine atom.
L represents a single bond or a divalent linking group. Examples of the divalent linking group include -COO-, -CO-, -O-, -S-, -SO-, -SO ₂ -, an alkylene group, a cycloalkylene group, an alkenylene group, and a linking group in which a plurality of these groups are linked together.
m and n each independently represent an integer of 0 or more. There is no particular upper limit to m and n, but they are often 2 or less, and more often 1 or less.

(Repeating unit represented by formula (B))
One example of a specific means for achieving the above (b) is a method in which a repeating unit represented by formula (B) is introduced into resin (A).

In formula (B), R _b1 to R _b4 each independently represent a hydrogen atom or an organic group, and at least two of R _b1 to R _b4 represent an organic group.
In addition, when at least one of the organic groups is a group in which a ring structure is directly linked to the main chain in the repeating unit, the type of the other organic groups is not particularly limited.
Furthermore, when none of the organic groups has a ring structure directly linked to the main chain in the repeating unit, at least two of the organic groups are substituents having three or more constituent atoms excluding hydrogen atoms.

Specific examples of the repeating unit represented by formula (B) include the following repeating units.

In the above formula, each R independently represents a hydrogen atom or an organic group, such as an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group, each of which may have a substituent.
Each R' independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an acyloxy group, a cyano group, a nitro group, an amino group, a halogen atom, an ester group (-OCOR'' or -COOR'': R'' is an alkyl group or a fluorinated alkyl group having 1 to 20 carbon atoms), or a carboxyl group. The alkyl group, the cycloalkyl group, the aryl group, the aralkyl group, and the alkenyl group may each have a substituent. In addition, a hydrogen atom bonded to a carbon atom in the group represented by R' may be substituted with a fluorine atom or an iodine atom.
m represents an integer of 0 or more. There is no particular upper limit to m, but it is often 2 or less, and more often 1 or less.

(Repeating unit represented by formula (C))
One example of a specific means for achieving the above (c) is a method in which a repeating unit represented by formula (C) is introduced into resin (A).

In formula (C), R _c1 to R _c4 each independently represent a hydrogen atom or an organic group, and at least one of R _c1 to R _c4 is a group having a hydrogen-bonding hydrogen atom within three atoms from a main chain carbon. In particular, in order to induce an interaction between the main chains of resin (A), it is preferable to have a hydrogen-bonding hydrogen atom within two atoms (closer to the main chain).

Specific examples of the repeating unit represented by formula (C) include the following repeating units.

In the above formula, R represents an organic group. Examples of the organic group include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, and an ester group (-OCOR or -COOR: R is an alkyl group or a fluorinated alkyl group having 1 to 20 carbon atoms), each of which may have a substituent.
R' represents a hydrogen atom or an organic group. Examples of the organic group include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and an alkenyl group. The hydrogen atom in the organic group may be substituted with a fluorine atom or an iodine atom.

(Repeating unit represented by formula (D))
One example of a specific means for achieving the above (d) is a method in which a repeating unit represented by formula (D) is introduced into resin (A).

In formula (D), "cyclic" represents a group that forms a main chain with a cyclic structure. The number of constituent atoms of the ring is not particularly limited.

Specific examples of the repeating unit represented by formula (D) include the following repeating units.

In the above formula, each R independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an acyloxy group, a cyano group, a nitro group, an amino group, a halogen atom, an ester group (-OCOR" or -COOR": R" is an alkyl group or a fluorinated alkyl group having 1 to 20 carbon atoms), or a carboxyl group. The alkyl group, the cycloalkyl group, the aryl group, the aralkyl group, and the alkenyl group may each have a substituent. In addition, a hydrogen atom bonded to a carbon atom in the group represented by R may be substituted with a fluorine atom or an iodine atom.
In the above formula, R' each independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an acyloxy group, a cyano group, a nitro group, an amino group, a halogen atom, an ester group (-OCOR" or -COOR": R" is an alkyl group or a fluorinated alkyl group having 1 to 20 carbon atoms), or a carboxyl group. The alkyl group, the cycloalkyl group, the aryl group, the aralkyl group, and the alkenyl group may each have a substituent. In addition, a hydrogen atom bonded to a carbon atom in the group represented by R' may be substituted with a fluorine atom or an iodine atom.
m represents an integer of 0 or more. There is no particular upper limit to m, but it is often 2 or less, and more often 1 or less.

(Repeating unit represented by formula (E))
One example of a specific means for achieving the above (e) is to introduce a repeating unit represented by formula (E) into resin (A).

In formula (E), each Re independently represents a hydrogen atom or an organic group, such as an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group, each of which may have a substituent.
"Cyclic" refers to a cyclic group containing carbon atoms in the main chain. The number of atoms contained in the cyclic group is not particularly limited.

Specific examples of the repeating unit represented by formula (E) include the following repeating units.

In the above formula, each R independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an acyloxy group, a cyano group, a nitro group, an amino group, a halogen atom, an ester group (-OCOR" or -COOR": R" is an alkyl group or a fluorinated alkyl group having 1 to 20 carbon atoms), or a carboxyl group. The alkyl group, the cycloalkyl group, the aryl group, the aralkyl group, and the alkenyl group may each have a substituent. In addition, a hydrogen atom bonded to a carbon atom in the group represented by R may be substituted with a fluorine atom or an iodine atom.
Each R' independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an acyloxy group, a cyano group, a nitro group, an amino group, a halogen atom, an ester group (-OCOR" or -COOR": R" is an alkyl group or a fluorinated alkyl group having 1 to 20 carbon atoms), or a carboxyl group. The alkyl group, the cycloalkyl group, the aryl group, the aralkyl group, and the alkenyl group may each have a substituent. In addition, a hydrogen atom bonded to a carbon atom in the group represented by R' may be substituted with a fluorine atom or an iodine atom.
m represents an integer of 0 or more. There is no particular upper limit to m, but it is often 2 or less, and more often 1 or less.
In addition, in formulae (E-2), (E-4), (E-6), and (E-8), two R's may be bonded to each other to form a ring.

The content of the repeating unit represented by formula (E) is preferably 5 mol% or more, more preferably 10 mol% or more, based on the total repeating units in resin (A). The upper limit is preferably 60 mol% or less, more preferably 55 mol% or less.

<Repeating Unit Having at Least One Group Selected from Lactone Group, Sultone Group, Carbonate Group, Hydroxyl Group, Cyano Group, and Alkali-Soluble Group>
The resin (A) may have a repeating unit having at least one type of group selected from a lactone group, a sultone group, a carbonate group, a hydroxyl group, a cyano group, and an alkali-soluble group.
Examples of the repeating unit having a lactone group, a sultone group, or a carbonate group contained in the resin (A) include the repeating units described above in <Repeat units having a lactone group, a sultone group, or a carbonate group>. The preferred content is also as described above in <Repeat units having a lactone group, a sultone group, or a carbonate group>.

The resin (A) may contain a repeating unit having a hydroxyl group or a cyano group, which improves the adhesion to the substrate and the affinity for the developer.
The repeating unit having a hydroxyl group or a cyano group is preferably a repeating unit having an alicyclic hydrocarbon structure substituted with a hydroxyl group or a cyano group.
The repeating unit having a hydroxyl group or a cyano group preferably does not have an acid-decomposable group. Examples of the repeating unit having a hydroxyl group or a cyano group include repeating units represented by the following general formulae (AIIa) to (AIId).

In general formulae (AIIa) to (AIId),
R _1c represents a hydrogen atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group.
R _2c to R _4c each independently represent a hydrogen atom, a hydroxyl group, or a cyano group. However, at least one of R _2c to R _4c represents a hydroxyl group or a cyano group. Preferably, one or two of R _2c to R _4c are a hydroxyl group, and the remaining are hydrogen atoms. More preferably, two of R _2c to R _4c are hydroxyl groups, and the remaining are hydrogen atoms.

The content of repeating units having a hydroxyl group or a cyano group is preferably 5 mol% or more, more preferably 10 mol% or more, based on the total repeating units in the resin (A). The upper limit is preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less.

Specific examples of repeating units having a hydroxyl group or a cyano group are listed below, but the present invention is not limited to these.

The resin (A) may have a repeating unit having an alkali-soluble group.
Examples of the alkali-soluble group include a carboxyl group, a sulfonamide group, a sulfonylimide group, a bisulfonylimide group, and an aliphatic alcohol group (e.g., a hexafluoroisopropanol group) substituted with an electron-withdrawing group at the α-position, and the carboxyl group is preferred. The resin (A) contains a repeating unit having an alkali-soluble group, which increases the resolution in contact hole applications.
Examples of the repeating unit having an alkali-soluble group include a repeating unit having an alkali-soluble group bonded directly to the main chain of a resin, such as a repeating unit of acrylic acid or methacrylic acid, or a repeating unit having an alkali-soluble group bonded to the main chain of a resin via a linking group, which may have a monocyclic or polycyclic cyclic hydrocarbon structure.
The repeating unit having an alkali-soluble group is preferably a repeating unit derived from acrylic acid or methacrylic acid.

The content of the repeating units having an alkali-soluble group is preferably 0 mol% or more, more preferably 3 mol% or more, and even more preferably 5 mol% or more, based on the total repeating units in the resin (A). The upper limit is preferably 20 mol% or less, more preferably 15 mol% or less, and even more preferably 10 mol% or less.

Specific examples of the repeating unit having an alkali-soluble group are shown below, but the invention is not limited thereto. In the specific examples, Rx represents H, _CH3 , _CH2OH or _CF3 .

As a repeating unit having at least one type of group selected from a lactone group, a hydroxyl group, a cyano group, and an alkali-soluble group, a repeating unit having at least two selected from a lactone group, a hydroxyl group, a cyano group, and an alkali-soluble group is preferred, a repeating unit having a cyano group and a lactone group is more preferred, and a repeating unit having a structure in which a cyano group is substituted for the lactone structure represented by general formula (LC1-4) is even more preferred.

<Repeating Unit Having an Alicyclic Hydrocarbon Structure and Not Showing Acid Decomposability>
Resin (A) may have an alicyclic hydrocarbon structure and a repeating unit that does not exhibit acid decomposition. This can reduce the elution of low molecular weight components from the resist film into the immersion liquid during immersion exposure. Examples of such repeating units include repeating units derived from 1-adamantyl (meth)acrylate, diamantyl (meth)acrylate, tricyclodecanyl (meth)acrylate, or cyclohexyl (meth)acrylate.

<Repeating unit represented by formula (III) having neither a hydroxyl group nor a cyano group>
The resin (A) may have a repeating unit represented by general formula (III) which does not have either a hydroxyl group or a cyano group.

In formula (III), _R5 represents a hydrocarbon group having at least one cyclic structure and having neither a hydroxyl group nor a cyano group.
Ra represents a hydrogen atom, an alkyl group or a -CH ₂ -O-Ra ₂ group, where Ra ₂ represents a hydrogen atom, an alkyl group or an acyl group.

The cyclic structure contained in _R5 includes a monocyclic hydrocarbon group and a polycyclic hydrocarbon group. Examples of the monocyclic hydrocarbon group include a cycloalkyl group having 3 to 12 carbon atoms (more preferably 3 to 7 carbon atoms) and a cycloalkenyl group having 3 to 12 carbon atoms.

Polycyclic hydrocarbon groups include ring assembly hydrocarbon groups and bridged cyclic hydrocarbon groups.
Examples of the bridged cyclic hydrocarbon ring include a bicyclic hydrocarbon ring, a tricyclic hydrocarbon ring, and a tetracyclic hydrocarbon ring, etc. In addition, the bridged cyclic hydrocarbon ring also includes a fused ring in which a plurality of 5- to 8-membered cycloalkane rings are condensed.
As the bridged cyclic hydrocarbon group, a norbornyl group, an adamantyl group, a bicyclooctanyl group, or a tricyclo[5,2,1,0 ^2,6 ]decanyl group is preferable, and a norbornyl group or an adamantyl group is more preferable.

The alicyclic hydrocarbon group may have a substituent, and examples of the substituent include a halogen atom, an alkyl group, a hydroxyl group protected by a protecting group, and an amino group protected by a protecting group.
The halogen atom is preferably a bromine atom, a chlorine atom or a fluorine atom.
The alkyl group is preferably a methyl group, an ethyl group, a butyl group, or a t-butyl group. The alkyl group may further have a substituent, and the substituent may be a halogen atom, an alkyl group, a hydroxyl group protected by a protecting group, or an amino group protected by a protecting group.

Examples of the protecting group include an alkyl group, a cycloalkyl group, an aralkyl group, a substituted methyl group, a substituted ethyl group, an alkoxycarbonyl group, and an aralkyloxycarbonyl group.
The alkyl group is preferably an alkyl group having 1 to 4 carbon atoms.
The substituted methyl group is preferably a methoxymethyl group, a methoxythiomethyl group, a benzyloxymethyl group, a t-butoxymethyl group, or a 2-methoxyethoxymethyl group.
The substituted ethyl group is preferably a 1-ethoxyethyl group or a 1-methyl-1-methoxyethyl group.
The acyl group is preferably an aliphatic acyl group having 1 to 6 carbon atoms, such as a formyl group, an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a valeryl group, or a pivaloyl group.
The alkoxycarbonyl group is preferably an alkoxycarbonyl group having 1 to 4 carbon atoms.

The content of the repeating unit represented by formula (III) having neither a hydroxyl group nor a cyano group is preferably from 0 to 40 mol %, more preferably from 0 to 20 mol %, based on all repeating units in the resin (A).
Specific examples of the repeating unit represented by formula (III) are shown below, but the invention is not limited thereto: In the formula, Ra represents H, _CH3 , _CH2OH , or _CF3 .

<Other repeating units>
Furthermore, the resin (A) may have a repeating unit other than the repeating units described above.
For example, resin (A) may have a repeating unit selected from the group consisting of a repeating unit having an oxathiane ring group, a repeating unit having an oxazolone ring group, a repeating unit having a dioxane ring group, and a repeating unit having a hydantoin ring group.
Examples of such repeating units are shown below.

In addition to the above repeating structural units, resin (A) may have various repeating structural units for the purpose of adjusting dry etching resistance, suitability for standard developing solutions, substrate adhesion, resist profile, resolution, heat resistance, sensitivity, etc.

It is also preferable that all of the repeating units of the resin (A) are (meth)acrylate repeating units (especially when the resist composition of the present invention is used as an ArF actinic ray-sensitive or radiation-sensitive resin composition). In this case, any of the repeating units may be used, in which all of the repeating units are methacrylate repeating units, all of the repeating units are acrylate repeating units, or all of the repeating units are a combination of methacrylate repeating units and acrylate repeating units, and it is preferable that the acrylate repeating units account for 50 mol % or less of the total repeating units.

The resin (A) can be synthesized according to a conventional method (for example, radical polymerization).
The weight average molecular weight of the resin (A) is preferably 1,000 to 200,000, more preferably 3,000 to 20,000, and even more preferably 5,000 to 15,000, as calculated in terms of polystyrene by the GPC method. By setting the weight average molecular weight of the resin (A) to 1,000 to 200,000, deterioration of heat resistance and dry etching resistance can be further suppressed. In addition, deterioration of developability and deterioration of film formability due to an increase in viscosity can be further suppressed.
The dispersity (molecular weight distribution) of the resin (A) is usually from 1 to 5, preferably from 1 to 3, more preferably from 1.2 to 3.0, and even more preferably from 1.2 to 2.0. The smaller the dispersity, the better the resolution and resist shape, and further the smoother the side walls of the resist pattern and the better the roughness.

In the resist composition of the present invention, the content of the resin (A) is preferably from 50 to 99.9 mass %, and more preferably from 60 to 99.0 mass %, based on the total solid content of the composition.
The solid content refers to the components in the composition excluding the solvent, and any components other than the solvent are considered to be solids even if they are liquid components.
The resin (A) may be used alone or in combination of two or more kinds.

[Acid Diffusion Controller]
The resist composition of the present invention may contain an acid diffusion controller.
The acid diffusion controller traps the acid generated from the photoacid generator during exposure and acts as a quencher to suppress the reaction of the acid-decomposable resin in the unexposed area caused by the excess acid generated. Examples of the acid diffusion controller that can be used include basic compounds (DA), basic compounds (DB) whose basicity is reduced or eliminated by irradiation with actinic rays or radiation, and onium salt compounds (DE) having a nitrogen atom in the cation moiety. In the resist composition of the present invention, known acid diffusion controllers can be appropriately used. For example, known compounds disclosed in paragraphs [0627] to [0664] of U.S. Patent Application Publication No. 2016/0070167A1, paragraphs [0095] to [0187] of U.S. Patent Application Publication No. 2015/0004544A1, paragraphs [0403] to [0423] of U.S. Patent Application Publication No. 2016/0237190A1, and paragraphs [0259] to [0328] of U.S. Patent Application Publication No. 2016/0274458A1 can be suitably used as the acid diffusion controller.

<Basic Compound (DA)>
As the basic compound (DA), compounds having structures represented by the following formulae (A) to (E) are preferred.

In general formulae (A) and (E),
R ²⁰⁰ , R ²⁰¹ and R ²⁰² may be the same or different and each independently represents a hydrogen atom, an alkyl group (preferably having 1 to 20 carbon atoms), a cycloalkyl group (preferably having 3 to 20 carbon atoms) or an aryl group (having 6 to 20 carbon atoms). R ²⁰¹ and R ²⁰² may be bonded to each other to form a ring.
R ²⁰³ , R ²⁰⁴ , R ²⁰⁵ and R ²⁰⁶ may be the same or different and each independently represents an alkyl group having 1 to 20 carbon atoms.

The alkyl group in the general formulae (A) and (E) may be substituted or unsubstituted.
As for the above alkyl group, the alkyl group having a substituent is preferably an aminoalkyl group having 1 to 20 carbon atoms, a hydroxyalkyl group having 1 to 20 carbon atoms, or a cyanoalkyl group having 1 to 20 carbon atoms.
The alkyl groups in the general formulae (A) and (E) are more preferably unsubstituted.

As the basic compound (DA), guanidine, aminopyrrolidine, pyrazole, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholine, or piperidine is preferred, and a compound having an imidazole structure, a diazabicyclo structure, an onium hydroxide structure, an onium carboxylate structure, a trialkylamine structure, an aniline structure, or a pyridine structure, an alkylamine derivative having a hydroxyl group and/or an ether bond, or an aniline derivative having a hydroxyl group and/or an ether bond is more preferred.

<Basic Compound (DB) Whose Basicity is Reduced or Lost by Irradiation with Actinic Rays or Radiation>
The basic compound (DB) (hereinafter also referred to as "compound (DB)") whose basicity is reduced or eliminated by irradiation with actinic rays or radiation is a compound that has a proton acceptor functional group and is decomposed by irradiation with actinic rays or radiation, and the proton acceptor property is reduced or eliminated, or the proton acceptor property is changed from a proton acceptor property to an acidic property.

A proton acceptor functional group is a functional group having a group or electrons that can electrostatically interact with a proton, and means, for example, a functional group having a macrocyclic structure such as a cyclic polyether, or a functional group having a nitrogen atom with an unshared electron pair that does not contribute to π conjugation. A nitrogen atom with an unshared electron pair that does not contribute to π conjugation is, for example, a nitrogen atom having the partial structure shown in the following formula.

Preferred partial structures of the proton acceptor functional group include, for example, a crown ether structure, an azacrown ether structure, a primary to tertiary amine structure, a pyridine structure, an imidazole structure, and a pyrazine structure.

Compound (DB) is decomposed by irradiation with actinic rays or radiation to generate a compound in which the proton acceptor property is reduced or eliminated, or the proton acceptor property is changed from a proton acceptor property to an acidic property. Here, the reduction or elimination of the proton acceptor property, or the change from a proton acceptor property to an acidic property, refers to a change in the proton acceptor property caused by the addition of a proton to a proton acceptor functional group, and specifically, when a proton adduct is generated from compound (DB) having a proton acceptor functional group and a proton, the equilibrium constant in the chemical equilibrium is reduced.
The proton acceptor property can be confirmed by measuring the pH.

The acid dissociation constant pKa of the compound generated by decomposition of compound (DB) upon exposure to actinic rays or radiation preferably satisfies pKa<-1, more preferably satisfies -13<pKa<-1, and even more preferably satisfies -13<pKa<-3.

The acid dissociation constant pKa can be determined using the method described above.

<Low molecular weight compound (DD) having a nitrogen atom and a group that is cleaved by the action of an acid>
The low molecular weight compound (DD) having a nitrogen atom and a group that can be eliminated by the action of an acid (hereinafter also referred to as "compound (DD)") is preferably an amine derivative having, on the nitrogen atom, a group that can be eliminated by the action of an acid.
The group which is eliminated by the action of an acid is preferably an acetal group, a carbonate group, a carbamate group, a tertiary ester group, a tertiary hydroxyl group, or a hemiaminal ether group, more preferably a carbamate group or a hemiaminal ether group.
The molecular weight of the compound (DD) is preferably from 100 to 1,000, more preferably from 100 to 700, and even more preferably from 100 to 500.
Compound (DD) may have a carbamate group having a protecting group on the nitrogen atom. The protecting group constituting the carbamate group is represented by the following general formula (d-1).

In general formula (d-1),
Each R _b independently represents a hydrogen atom, an alkyl group (preferably having 1 to 10 carbon atoms), a cycloalkyl group (preferably having 3 to 30 carbon atoms), an aryl group (preferably having 3 to 30 carbon atoms), an aralkyl group (preferably having 1 to 10 carbon atoms), or an alkoxyalkyl group (preferably having 1 to 10 carbon atoms). _{R b} may be linked to each other to form a ring.
The alkyl group, cycloalkyl group, aryl group, and aralkyl group represented by _Rb may each independently be substituted with a functional group such as a hydroxyl group, a cyano group, an amino group, a pyrrolidino group, a piperidino group, a morpholino group, or an oxo group, an alkoxy group, or a halogen atom. The same applies to the alkoxyalkyl group represented by _Rb .

_Rb is preferably a linear or branched alkyl group, a cycloalkyl group, or an aryl group, and more preferably a linear or branched alkyl group, or a cycloalkyl group.
Examples of the ring formed by two _Rb's linked together include alicyclic hydrocarbons, aromatic hydrocarbons, heterocyclic hydrocarbons, and derivatives thereof.
Specific examples of the structure of the group represented by formula (d-1) include, but are not limited to, the structures disclosed in paragraph [0466] of US Patent Publication US 2012/0135348 A1.

It is preferable that compound (DD) is a compound represented by the following general formula (6).

In general formula (6),
l represents an integer of 0 to 2, m represents an integer of 1 to 3, and l+m=3 is satisfied.
R _a represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group. When l is 2, the two R _a may be the same or different, and the two R _a may be linked together to form a heterocycle together with the nitrogen atom in the formula. This heterocycle may contain a heteroatom other than the nitrogen atom in the formula.
R _b has the same meaning as R _b in formula (d-1) above, and preferred examples are also the same.
In general formula (6), the alkyl group, cycloalkyl group, aryl group, and aralkyl group represented by R _a may each independently be substituted with the same group as the group described above as the optionally substituted alkyl group, cycloalkyl group, aryl group, and aralkyl group represented by R _b .

Specific examples of the alkyl group, cycloalkyl group, aryl group, and aralkyl group (which may be substituted with the above groups) for R _a include the same groups as the specific examples given above for R _b .
Specific examples of particularly preferred compounds (DD) in the present invention include, but are not limited to, the compounds disclosed in paragraph [0475] of US Patent Application Publication No. 2012/0135348A1.

<Onium Salt Compound Having Nitrogen Atom in Cation Moiety (DE)>
The onium salt compound (DE) having a nitrogen atom in the cationic moiety (hereinafter also referred to as "compound (DE)") is preferably a compound having a basic moiety containing a nitrogen atom in the cationic moiety. The basic moiety is preferably an amino group, more preferably an aliphatic amino group. It is further preferable that all atoms adjacent to the nitrogen atom in the basic moiety are hydrogen atoms or carbon atoms. In addition, from the viewpoint of improving basicity, it is preferable that an electron-withdrawing functional group (carbonyl group, sulfonyl group, cyano group, halogen atom, etc.) is not directly bonded to the nitrogen atom.
Preferred specific examples of the compound (DE) include, but are not limited to, the compounds disclosed in paragraph [0203] of U.S. Patent Application Publication No. 2015/0309408 A1.

Preferred examples of acid diffusion control agents are shown below.

When the resist composition of the present invention contains an acid diffusion controller, the content of the acid diffusion controller (the total content when a plurality of types are present) is preferably 0.1 to 11.0 mass %, more preferably 0.1 to 10.0 mass %, even more preferably 0.1 to 8.0 mass %, and particularly preferably 0.1 to 5.0 mass %, based on the total solid content of the composition.
In the resist composition of the present invention, the acid diffusion controller may be used alone or in combination of two or more kinds.

[Hydrophobic resin]
The resist composition of the present invention may contain, in addition to the above-mentioned resin (A), a hydrophobic resin different from the resin (A).
The hydrophobic resin is preferably designed to be unevenly distributed on the surface of the resist film, but unlike a surfactant, it does not necessarily have to have a hydrophilic group in the molecule, and does not necessarily have to contribute to uniformly mixing polar and non-polar substances.
The effects of adding a hydrophobic resin include control of the static and dynamic contact angle of the resist film surface with water, and suppression of outgassing.

From the viewpoint of uneven distribution on the surface layer of the film, the hydrophobic resin preferably has one or more of "fluorine atoms", "silicon atoms", and " _CH3 partial structures contained in the side chain portion of the resin", and more preferably has two or more of them. In addition, the hydrophobic resin preferably has a hydrocarbon group having 5 or more carbon atoms. These groups may be present in the main chain of the resin or may be substituted on the side chain.

When the hydrophobic resin contains fluorine atoms and/or silicon atoms, the fluorine atoms and/or silicon atoms in the hydrophobic resin may be contained in the main chain or in the side chain of the resin.

When the hydrophobic resin contains a fluorine atom, the partial structure having a fluorine atom is preferably an alkyl group having a fluorine atom, a cycloalkyl group having a fluorine atom, or an aryl group having a fluorine atom.
The alkyl group having a fluorine atom (preferably having 1 to 10 carbon atoms, more preferably having 1 to 4 carbon atoms) is a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and may further have a substituent other than a fluorine atom.
The fluorine atom-containing cycloalkyl group is a monocyclic or polycyclic cycloalkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and may further have a substituent other than a fluorine atom.
Examples of aryl groups having a fluorine atom include aryl groups such as phenyl and naphthyl groups in which at least one hydrogen atom is substituted with a fluorine atom, and the aryl group may further have a substituent other than a fluorine atom.
Examples of the repeating unit having a fluorine atom or a silicon atom include those exemplified in paragraph [0519] of US 2012/0251948 A1.

As mentioned above, it is also preferred that the hydrophobic resin contains a _CH3 moiety in the side chain portion.
Here, the _CH3 partial structure possessed by the side chain portion in the hydrophobic resin includes the _CH3 partial structure possessed by an ethyl group, a propyl group, and the like.
On the other hand, a methyl group directly bonded to the main chain of a hydrophobic resin (for example, an α-methyl group of a repeating unit having a methacrylic acid structure) has a small contribution to the uneven distribution of the hydrophobic resin on the surface due to the influence of the main chain, and is therefore not included in the _CH3 partial structure in the present invention.

With regard to hydrophobic resins, please refer to the descriptions in paragraphs [0348] to [0415] of JP 2014-010245 A, the contents of which are incorporated herein by reference.

In addition, the resins described in JP-A-2011-248019, JP-A-2010-175859, and JP-A-2012-032544 can also be preferably used as hydrophobic resins.

Preferred examples of monomers corresponding to the repeating units that make up the hydrophobic resin are shown below.

When the resist composition of the present invention contains a hydrophobic resin, the content of the hydrophobic resin is preferably 0.01 to 15.0 mass% relative to the total solid content of the composition, more preferably 0.1 to 10.0 mass%, even more preferably 0.1 to 7.0 mass%, and particularly preferably 0.1 to 5.0 mass%.

[Surfactant]
The resist composition of the present invention may contain a surfactant. By containing a surfactant, it is possible to form a pattern with excellent adhesion and fewer development defects.
As the surfactant, a fluorine-based and/or silicon-based surfactant is preferred.
Examples of fluorine-based and/or silicone-based surfactants include those described in paragraph [0276] of the specification of U.S. Patent Application Publication No. 2008/0248425. Other examples include EFTOP EF301 or EF303 (manufactured by Shin-Akita Chemical Industry Co., Ltd.); Fluorad FC430, 431 or 4430 (manufactured by Sumitomo 3M Limited); Megafac F171, F173, F176, F189, F113, F110, F177, F120 or R08 (manufactured by DIC Corporation); Surflon S-382, SC101, 102, 103, 104, 105 or 106 (manufactured by Asahi Glass Co., Ltd.); Troysol S-366 (manufactured by Troy Chemical Co., Ltd.); GF-300 or GF-150 (manufactured by Toagosei Chemical Co., Ltd. ... Flon S-393 (manufactured by Seimi Chemical Co., Ltd.); EFTOP EF121, EF122A, EF122B, RF122C, EF125M, EF135M, EF351, EF352, EF801, EF802 or EF601 (manufactured by JEMCO Co., Ltd.); PF636, PF656, PF6320 or PF6520 (manufactured by OMNOVA); KH-20 (manufactured by Asahi Kasei Co., Ltd.); FTX-204G, 208G, 218G, 230G, 204D, 208D, 212D, 218D or 222D (manufactured by Neos Co., Ltd.) may also be used. Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can also be used as a silicon-based surfactant.

In addition to the above-mentioned known surfactants, the surfactant may be synthesized using a fluoroaliphatic compound produced by a telomerization method (also called a telomer method) or an oligomerization method (also called an oligomer method). Specifically, a polymer having a fluoroaliphatic group derived from the fluoroaliphatic compound may be used as the surfactant. The fluoroaliphatic compound may be synthesized by the method described in JP-A-2002-90991, for example.
The polymer having a fluoroaliphatic group is preferably a copolymer of a monomer having a fluoroaliphatic group and a (poly(oxyalkylene)) acrylate and/or a (poly(oxyalkylene)) methacrylate, and may be irregularly distributed or block copolymerized. The poly(oxyalkylene) group may be a poly(oxyethylene) group, a poly(oxypropylene) group, or a poly(oxybutylene) group, and may also be a unit having alkylenes of different chain lengths within the same chain length, such as poly(block linkage of oxyethylene, oxypropylene, and oxyethylene) or poly(block linkage of oxyethylene and oxypropylene). Furthermore, the copolymer of a monomer having a fluoroaliphatic group and a (poly(oxyalkylene)) acrylate (or methacrylate) may be not only a binary copolymer, but also a ternary or higher copolymer in which two or more different monomers having a fluoroaliphatic group and two or more different (poly(oxyalkylene)) acrylates (or methacrylates) are simultaneously copolymerized.
For example, commercially available surfactants include Megafac F178, F-470, F-473, F-475, F-476, and F-472 (manufactured by DIC Corporation), copolymers of an acrylate (or methacrylate) having a C ₆ F ₁₃ group and a (poly(oxyalkylene)) acrylate (or methacrylate), and copolymers of an acrylate (or methacrylate) having a C ₃ F ₇ group, a (poly(oxyethylene)) acrylate (or methacrylate), and a (poly(oxypropylene)) acrylate (or methacrylate).
Furthermore, surfactants other than the fluorine-based and/or silicon-based surfactants described in paragraph [0280] of US Patent Application Publication No. 2008/0248425 may be used.

These surfactants may be used alone or in combination of two or more.
The content of the surfactant is preferably from 0.0001 to 2 mass %, and more preferably from 0.0005 to 1 mass %, based on the total solid content of the resist composition of the present invention.

〔solvent〕
The resist composition of the present invention contains a solvent. The solvent preferably contains at least one selected from the group consisting of (M1) propylene glycol monoalkyl ether carboxylate and (M2) propylene glycol monoalkyl ether, lactate ester, acetate ester, alkoxypropionate ester, chain ketone, cyclic ketone, lactone, and alkylene carbonate. The solvent may further contain a component other than the components (M1) and (M2).

The inventors have found that using such a solvent in combination with the above-mentioned resin (A) improves the coatability of the composition and enables the formation of a pattern with fewer development defects. The reason for this is not entirely clear, but the inventors believe that this is due to the fact that these solvents have a good balance of the solubility, boiling point, and viscosity of the above-mentioned resin (A), making it possible to suppress unevenness in the film thickness of the composition film and the occurrence of precipitates during spin coating.

As component (M1), at least one selected from the group consisting of propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether propionate, and propylene glycol monoethyl ether acetate is preferred, with propylene glycol monomethyl ether acetate (PGMEA) being more preferred.

As the component (M2), the following are preferred.
As the propylene glycol monoalkyl ether, propylene glycol monomethyl ether (PGME) or propylene glycol monoethyl ether (PGEE) is preferred.
The lactate ester is preferably ethyl lactate, butyl lactate, or propyl lactate.
The acetate ester is preferably methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, propyl acetate, isoamyl acetate, methyl formate, ethyl formate, butyl formate, propyl formate, or 3-methoxybutyl acetate.
Also preferred is butyl butyrate.
As the alkoxypropionate, methyl 3-methoxypropionate (MMP) or ethyl 3-ethoxypropionate (EEP) is preferred.
As the chain ketone, 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 2-heptanone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, phenylacetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone, or methyl amyl ketone is preferred.
The cyclic ketone is preferably methylcyclohexanone, isophorone, or cyclohexanone.
The lactone is preferably γ-butyrolactone.
As the alkylene carbonate, propylene carbonate is preferred.

As component (M2), propylene glycol monomethyl ether (PGME), ethyl lactate, ethyl 3-ethoxypropionate, methyl amyl ketone, cyclohexanone, butyl acetate, pentyl acetate, gamma-butyrolactone, or propylene carbonate are more preferred.

In addition to the above components, it is preferable to use an ester-based solvent having 7 or more carbon atoms (preferably 7 to 14, more preferably 7 to 12, and even more preferably 7 to 10) and 2 or less heteroatoms.

Preferred ester solvents having 7 or more carbon atoms and 2 or less heteroatoms are amyl acetate, 2-methylbutyl acetate, 1-methylbutyl acetate, hexyl acetate, pentyl propionate, hexyl propionate, butyl propionate, isobutyl isobutyrate, heptyl propionate, or butyl butanoate, with isoamyl acetate being more preferred.

As the component (M2), those having a flash point (hereinafter also referred to as fp) of 37° C. or more are preferable. As such a component (M2), propylene glycol monomethyl ether (fp: 47° C.), ethyl lactate (fp: 53° C.), ethyl 3-ethoxypropionate (fp: 49° C.), methyl amyl ketone (fp: 42° C.), cyclohexanone (fp: 44° C.), pentyl acetate (fp: 45° C.), methyl 2-hydroxyisobutyrate (fp: 45° C.), γ-butyrolactone (fp: 101° C.), or propylene carbonate (fp: 132° C.) are preferable. Among these, propylene glycol monoethyl ether, ethyl lactate, pentyl acetate, or cyclohexanone are more preferable, and propylene glycol monoethyl ether or ethyl lactate are even more preferable.
The "flash point" herein refers to the value listed in the reagent catalog of Tokyo Chemical Industry Co., Ltd. or Sigma-Aldrich Co.

The mass ratio (M1/M2) of the mixed solvent of components (M1) and (M2) is preferably in the range of 100/0 to 15/85, and more preferably in the range of 100/0 to 40/60. By adopting such a configuration, it is possible to further reduce the number of development defects.

As described above, the solvent may further contain components other than components (M1) and (M2). In this case, the content of components other than components (M1) and (M2) is preferably in the range of 30 mass% or less, more preferably in the range of 5 to 30 mass%, based on the total amount of the solvent.

The content of the solvent in the resist composition of the present invention is preferably determined so that the solids concentration is 0.5 to 30% by mass, and more preferably 1 to 20% by mass. This provides better coatability for the resist composition of the present invention. As mentioned above, "solids" refers to components that form a resist film, and does not include solvents. Furthermore, any component that forms a resist film is considered to be a solid even if it is in a liquid state.

<Other additives>
The resist composition of the present invention may further contain a resin other than those mentioned above, a crosslinking agent, an acid amplifier, a dye, a plasticizer, a photosensitizer, a light absorber, an alkali-soluble resin, a dissolution inhibitor, a dissolution promoter, or the like.

[Method of Preparing Resist Composition]
<Method of adjusting moisture content>
An example of a method for reducing the moisture content of a resist composition to a predetermined value or less is shown below. The following methods may be carried out alone or in combination of two or more methods.
(1) A method in which the resist composition is prepared in a nitrogen atmosphere and/or a dry atmosphere:
By carrying out the mixing step of the components constituting the resist composition under a nitrogen atmosphere, it is possible to suppress the mixing of moisture during the preparation of the resist composition. Furthermore, when the resist composition contains a highly hygroscopic resin (A) and/or a highly hygroscopic photoacid generator, it is also preferable to carry out the mixing step of the components constituting the resist composition under a dry atmosphere (for example, humidity of 50% or less).
(2) Method for reducing the moisture content of each component (raw material component) constituting the resist composition:
The moisture content of the resist composition can be reduced by reducing the moisture content of each component (raw material component) that constitutes the resist composition itself. Specifically, one example of such a method is to vacuum dry each component (raw material component) to be blended into the resist composition prior to preparation of the resist composition.
The vacuum drying treatment may be carried out at room temperature or with heating.
By subjecting the resin (A), which may be contained in a large amount in the resist composition, to a vacuum drying treatment, the moisture content of the finally obtained resist composition can be further reduced. An example of the vacuum drying treatment of the resin (A) is a treatment in which the resin is dried under reduced pressure and heating (e.g., 15 mmHg; 40 to 60° C.) for a predetermined period of time (for example, preferably 30 minutes to 24 hours, more preferably 1 hour to 16 hours, and even more preferably adjusted within a range of 2 hours to 12 hours).
(3) Dehydration method using molecular sieves:
The water content of the resist composition can be reduced by dehydrating each of the components (raw material components) constituting the resist composition and/or the resist composition with a molecular sieve (e.g., a product of Union Showa Co., Ltd.) In particular, dehydrating each of the components (raw material components) constituting the resist composition with a molecular sieve makes it easier to reduce the water content of the final resist composition.

A specific example of a method for preparing the resist composition of the present invention will now be described.
In the resist composition, the content of metal atoms is preferably reduced.

In the following, first a specific example of a method for reducing the content of metal atoms in a resist composition will be described, and then a specific example of a method for preparing a resist composition will be described.
The method for reducing the content of metal atoms in the resist composition includes, for example, an adjustment method by filtration using a filter. The filter pore size is preferably less than 100 nm, more preferably 10 nm or less, and even more preferably 5 nm or less. The filter is preferably made of polytetrafluoroethylene, polyethylene, or nylon. The filter may be made of a composite material combining the above filter material and an ion exchange medium. The filter may be used after being washed in advance with an organic solvent. In the filter filtration process, multiple types of filters may be connected in series or parallel. When multiple types of filters are used, filters with different pore sizes and/or materials may be used in combination. In addition, various materials may be filtered multiple times, and the process of filtering multiple times may be a circulation filtration process.

Methods for reducing the content of metal atoms in a resist composition include selecting raw materials with a low metal content as the raw materials constituting the various materials in the resist composition, filtering the raw materials constituting the various materials in the resist composition, and performing distillation under conditions that minimize contamination as much as possible, for example by lining the inside of the apparatus with Teflon (registered trademark).

In addition, as a method for reducing the content of metal atoms in the resist composition, in addition to the above-mentioned filter filtration, removal with an adsorbent may be performed, or a combination of filter filtration and an adsorbent may be used. As the adsorbent, a known adsorbent may be used, for example, an inorganic adsorbent such as silica gel or zeolite, or an organic adsorbent such as activated carbon.
In order to reduce the content of metal atoms in the resist composition, it is necessary to prevent the incorporation of metal impurities during the manufacturing process. Whether or not metal impurities have been sufficiently removed from the manufacturing equipment can be confirmed by measuring the content of metal components contained in the cleaning solution used to clean the manufacturing equipment.

Next, a specific example of a method for preparing a resist composition will be described.
In producing the resist composition, in order to adjust the water content of the final resist composition to a specified value or less, a step of reducing the water content of each of the components (raw material components) constituting the resist composition, and/or the resist composition itself, is carried out by the method described above.

In the production of the resist composition, for example, various components such as the above-mentioned resin and photoacid generator are preferably dissolved in a solvent, and then filtration (which may be circulating filtration) is performed using multiple filters made of different materials. For example, it is preferable to connect a polyethylene filter with a pore size of 50 nm, a nylon filter with a pore size of 10 nm, and a polyethylene filter with a pore size of 3 to 5 nm in series and perform filtration. A method of performing circulating filtration two or more times is also preferable for the filtration. The above filtration step also has the effect of reducing the content of metal atoms in the resist composition. The smaller the pressure difference between the filters, the more preferable, and generally 0.1 MPa or less, preferably 0.05 MPa or less, and more preferably 0.01 MPa or less. The smaller the pressure difference between the filter and the filling nozzle, the more preferable, and generally 0.5 MPa or less, preferably 0.2 MPa or less, and more preferably 0.1 MPa or less.
As a method for carrying out circulating filtration using a filter in the production of the resist composition, for example, a method in which circulating filtration is carried out two or more times using a polytetrafluoroethylene filter having a pore size of 50 nm is also preferred.

It is preferable to replace the inside of the resist composition production apparatus with an inert gas such as nitrogen, which can prevent active gases such as oxygen from dissolving in the resist composition.
The resist composition is filtered through a filter and then filled into a clean container. The resist composition filled into the container is preferably stored in a refrigerator. This suppresses deterioration of performance over time. The shorter the time from the completion of filling the resist composition into the container to the start of refrigerated storage, the more preferable, and is generally within 24 hours, preferably within 16 hours, more preferably within 12 hours, and even more preferably within 10 hours. The storage temperature is preferably 0 to 15°C, more preferably 0 to 10°C, and even more preferably 0 to 5°C.

[Resist film and pattern forming method]
The resist composition of the present invention can be used to form a resist film, and further, a pattern. The procedure for the pattern formation method using the resist composition of the present invention is not particularly limited, but it is preferable that the method includes the following steps.
Step 1: Forming a resist film on a support (substrate) using a resist composition. Step 2: Exposing the resist film to light. Step 3: Developing the exposed resist film using a developer. The procedures for each of the above steps will be described in detail below.

[Step 1: Resist film formation step]
Step 1 is a step of forming a resist film on a support (substrate) using a resist composition.
The definition of the resist composition and the method for preparing the resist composition are as described above.

Next, a method for forming a resist film on a substrate using the resist composition will be described.
An example of a method for forming a resist film on a substrate using a resist composition is a method in which the resist composition is applied onto a substrate.

The resist composition can be applied onto a substrate (e.g., silicon, silicon dioxide-coated) such as those used in the manufacture of integrated circuit elements by a suitable application method such as a spinner or coater. The preferred application method is spin coating using a spinner. The rotation speed when spin coating using a spinner is preferably 1000 to 3000 rpm.
After coating the resist composition, the substrate may be dried to form a resist film. If necessary, various undercoats (inorganic films, organic films, anti-reflective films) may be formed under the resist film.

Drying methods include a method of drying by heating. Heating can be performed by means provided in a normal exposure machine and/or developing machine, and may also be performed using a hot plate or the like. The heating temperature is preferably 80 to 150°C, more preferably 80 to 140°C, and even more preferably 80 to 130°C. The heating time is preferably 30 to 1000 seconds, more preferably 60 to 800 seconds, and even more preferably 60 to 600 seconds.

The thickness of the resist film is not particularly limited, but a thickness of 10 to 150 nm is preferable, and 15 to 100 nm is more preferable, as it allows the formation of fine patterns with higher precision.

A top coat may be formed on the resist film using a top coat composition.
It is preferable that the top coat composition does not mix with the resist film and can be applied uniformly onto the resist film.
It is also preferable to dry the resist film before forming the top coat. Next, a top coat composition is applied onto the obtained resist film by the same means as in the above-mentioned method for forming the resist film, and then dried to form the top coat.
The thickness of the top coat is preferably from 10 to 200 nm, and more preferably from 20 to 100 nm.
The topcoat composition includes, for example, a resin, an additive, and a solvent.
The resin may be the same as the hydrophobic resin described above. The content of the resin is preferably 50 to 99.9% by mass, more preferably 60 to 99.7% by mass, based on the total solid content of the top coat composition. Note that the "solid content" referred to here refers to the components forming the top coat, and does not include the solvent. In addition, any component that forms the top coat is considered to be a solid content even if it is in a liquid state.
As the additive, the above-mentioned acid diffusion control agent can be used. In addition, a compound having a radical trap group, such as a compound having an N-oxyl free radical group, can also be used. An example of such a compound is the [4-(benzoyloxy)-2,2,6,6-tetramethylpiperidinooxy] radical. The content of the additive is preferably 0.01 to 20 mass %, more preferably 0.1 to 15 mass %, based on the total solid content of the top coat composition.
The above solvent preferably does not dissolve the resist film, and examples thereof include alcohol-based solvents (such as 4-methyl-2-pentanol), ether-based solvents (such as diisoamyl ether), ester-based solvents, fluorine-based solvents, and hydrocarbon-based solvents (such as n-decane).
The content of the solvent in the top coat composition is preferably determined so that the solids concentration is 0.5 to 30% by mass, and more preferably 1 to 20% by mass.
The top coat composition may contain a surfactant in addition to the above-mentioned additives, and as the surfactant, a surfactant that may be contained in the resist composition of the present invention can be used. The content of the surfactant is preferably 0.0001 to 2 mass %, more preferably 0.0005 to 1 mass %, based on the total solid content of the top coat composition.
In addition, the top coat is not particularly limited, and a conventionally known top coat can be formed by a conventionally known method. For example, a top coat can be formed based on the description in paragraphs [0072] to [0082] of JP2014-059543A.
For example, it is preferable to form a top coat containing a basic compound such as that described in JP 2013-61648 A on the resist film. Specific examples of the basic compound that may be contained in the top coat include the basic compounds that may be contained in the resist composition of the present invention.
The top coat preferably contains a compound containing at least one group or bond selected from the group consisting of an ether bond, a thioether bond, a hydroxyl group, a thiol group, a carbonyl bond, and an ester bond.

[Step 2: Exposure Step]
Step 2 is a step of exposing the resist film to light.
The exposure method may be a method in which the formed resist film is irradiated with actinic rays or radiation through a predetermined mask.
Examples of actinic rays or radiation include infrared light, visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light, X-rays, and electron beams, and preferably far ultraviolet light having a wavelength of 250 nm or less, more preferably 220 nm or less, and particularly preferably 1 to 200 nm, specifically, KrF excimer laser (248 nm), ArF excimer laser (193 nm), _F2 excimer laser (157 nm), EUV (13 nm), X-rays, and electron beams.

After exposure, it is preferable to perform baking (heating) before development, which promotes the reaction of the exposed area and improves the sensitivity and pattern shape.
The heating temperature is preferably from 80 to 150°C, more preferably from 80 to 140°C, and even more preferably from 80 to 130°C.
The heating time is preferably from 10 to 1,000 seconds, more preferably from 10 to 180 seconds, and even more preferably from 30 to 120 seconds.
Heating can be carried out by a means provided in a normal exposure machine and/or a developing machine, and may also be carried out using a hot plate or the like.
This step is also called post-exposure bake.

[Step 3: Development Step]
Step 3 is a step of developing the exposed resist film with a developer to form a pattern.

The developing method includes a method of immersing a substrate in a tank filled with a developing solution for a certain period of time (dip method), a method of piling up the developing solution on the substrate surface by surface tension and leaving it to stand for a certain period of time to develop the substrate (paddle method), a method of spraying the developing solution on the substrate surface (spray method), and a method of continuously discharging the developing solution while scanning a developing solution discharge nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispense method).
After the development step, a step of stopping the development while replacing the solvent with another solvent may be carried out.
The development time is not particularly limited as long as the resin in the unexposed area is sufficiently dissolved, and is preferably from 10 to 300 seconds, more preferably from 20 to 120 seconds.
The temperature of the developer is preferably from 0 to 50°C, and more preferably from 15 to 35°C.

The developer may be an alkaline developer or an organic solvent developer.
The alkaline developer is preferably an aqueous alkaline solution containing an alkali. The type of the aqueous alkaline solution is not particularly limited, but examples include an aqueous alkaline solution containing a quaternary ammonium salt such as tetramethylammonium hydroxide, an inorganic alkali, a primary amine, a secondary amine, a tertiary amine, an alcohol amine, or a cyclic amine. In particular, the alkaline developer is preferably an aqueous solution of a quaternary ammonium salt such as tetramethylammonium hydroxide (TMAH). The alkaline developer may contain an appropriate amount of alcohols, surfactants, etc. The alkaline concentration of the alkaline developer is usually 0.1 to 20% by mass. The pH of the alkaline developer is usually 10.0 to 15.0.

The organic solvent developer is a developer that contains an organic solvent.
The vapor pressure of the organic solvent contained in the organic solvent developer (the overall vapor pressure in the case of a mixed solvent) is preferably 5 kPa or less, more preferably 3 kPa or less, and even more preferably 2 kPa or less at 20° C. By setting the vapor pressure of the organic solvent to 5 kPa or less, evaporation of the developer on the substrate or in the developing cup is suppressed, improving the temperature uniformity within the wafer surface, and as a result, improving the dimensional uniformity within the wafer surface.

Organic solvents used in organic solvent developers include known organic solvents, such as ester-based solvents, ketone-based solvents, alcohol-based solvents, amide-based solvents, ether-based solvents, and hydrocarbon-based solvents.

When EUV and electron beams are used in the exposure process, it is preferable that the organic solvent contained in the organic solvent developer is an ester-based solvent having 7 or more carbon atoms (preferably 7 to 14, more preferably 7 to 12, and even more preferably 7 to 10) and 2 or less heteroatoms, since this can suppress swelling of the resist film.

The heteroatoms of the ester solvent are atoms other than carbon and hydrogen atoms, such as oxygen atoms, nitrogen atoms, and sulfur atoms. The number of heteroatoms is preferably 2 or less.

Preferred ester solvents having 7 or more carbon atoms and 2 or less heteroatoms include amyl acetate, isoamyl acetate, 2-methylbutyl acetate, 1-methylbutyl acetate, hexyl acetate, pentyl propionate, hexyl propionate, butyl propionate, isobutyl isobutyrate, heptyl propionate, and butyl butanoate, with isoamyl acetate being more preferred.

When EUV and electron beams are used in the exposure step, the organic solvent contained in the organic solvent developer may be a mixed solvent of the ester solvent and the hydrocarbon solvent, or a mixed solvent of the ketone solvent and the hydrocarbon solvent, instead of an ester solvent having 7 or more carbon atoms and 2 or less heteroatoms. Even in this case, it is effective in suppressing swelling of the resist film.

When an ester solvent and a hydrocarbon solvent are used in combination, it is preferable to use isoamyl acetate as the ester solvent. In addition, as the hydrocarbon solvent, a saturated hydrocarbon solvent (e.g., octane, nonane, decane, dodecane, undecane, hexadecane, etc.) is preferable in terms of adjusting the solubility of the resist film.

When a ketone solvent and a hydrocarbon solvent are used in combination, it is preferable to use 2-heptanone as the ketone solvent. In addition, from the viewpoint of adjusting the solubility of the resist film, it is preferable to use a saturated hydrocarbon solvent (e.g., octane, nonane, decane, dodecane, undecane, hexadecane, etc.) as the hydrocarbon solvent.

When using the above mixed solvent, the content of the hydrocarbon-based solvent is not particularly limited since it depends on the solvent solubility of the resist film, and the required amount can be determined by appropriate preparation.

The above organic solvents may be mixed in combination, or may be mixed with other solvents or water. However, in order to fully achieve the effects of the present invention, it is preferable that the water content of the developer as a whole is less than 10% by mass, and it is more preferable that the developer contains substantially no water. The concentration of the organic solvent (total when multiple organic solvents are mixed) in the developer is preferably 50% by mass or more, more preferably 50 to 100% by mass, even more preferably 85 to 100% by mass, particularly preferably 90 to 100% by mass, and most preferably 95 to 100% by mass.

[Other steps]
The above pattern formation method preferably includes, after step 3, a step of cleaning with a rinsing liquid.
The rinse liquid used in the rinse step following the step of developing with a developer may be, for example, pure water, to which an appropriate amount of a surfactant may be added.
A suitable amount of a surfactant may be added to the rinse solution.

The method of the rinsing step is not particularly limited, but examples thereof include a method of continuously discharging a rinsing liquid onto a substrate rotating at a constant speed (spin coating method), a method of immersing a substrate in a tank filled with the rinsing liquid for a certain period of time (dip method), and a method of spraying the rinsing liquid onto the substrate surface (spray method).
The pattern forming method of the present invention may also include a heating step (Post Bake) after the rinsing step. This step removes the developer and rinsing solution remaining between the patterns and inside the pattern due to baking. This step also has the effect of annealing the resist pattern and improving the surface roughness of the pattern. The heating step after the rinsing step is usually performed at 40 to 250°C (preferably 90 to 200°C) for usually 10 seconds to 3 minutes (preferably 30 to 120 seconds).

Furthermore, the substrate may be etched using the formed pattern as a mask. That is, the substrate (or the underlayer film and the substrate) may be processed using the pattern formed in step 3 as a mask to form a pattern on the substrate.
The method for processing the substrate (or the underlayer film and the substrate) is not particularly limited, but a method in which the pattern formed in step 3 is used as a mask to perform dry etching on the substrate (or the underlayer film and the substrate) to form a pattern on the substrate is preferred.
The dry etching may be a single-stage etching or a multi-stage etching. If the etching is a multi-stage etching, each stage of the etching may be the same process or different processes.
Any known method can be used for the etching, and various conditions, etc. are appropriately determined depending on the type or use of the substrate. For example, etching can be performed according to the method described in "Chapter 4 Etching" of "Semiconductor Processing Textbook, Fourth Edition, Published in 2007, Publisher: SEMI Japan."
Among these, oxygen plasma etching is preferable as the dry etching.

The various materials other than the resist composition used in the pattern formation method of the present invention (e.g., developer, rinse solution, anti-reflective film forming composition, top coat forming composition, etc.) preferably have fewer impurities such as metals (e.g., Na, K, Ca, Fe, Cu, Mg, Al, Li, Cr, Ni, Sn, Ag, As, Au, Ba, Cd, Co, Pb, Ti, V, W, and Zn, etc.). The content of impurities contained in these materials is preferably, for example, 1 ppm by mass or less.

As a method for reducing impurities such as metals in various materials other than the resist composition, for example, filtration using a filter can be mentioned. The filter pore size is preferably less than 100 nm, more preferably 10 nm or less, and even more preferably 5 nm or less. As the filter, a filter made of polytetrafluoroethylene, polyethylene, or nylon is preferable. The filter may be composed of a composite material combining the above filter material and an ion exchange medium. The filter may be one that has been washed in advance with an organic solvent. In the filter filtration process, multiple types of filters may be connected in series or parallel. When multiple types of filters are used, filters with different pore sizes and/or materials may be used in combination. In addition, various materials may be filtered multiple times, and the process of filtering multiple times may be a circulation filtration process.

In addition, methods for reducing impurities such as metals in various materials other than the resist composition include selecting raw materials with a low metal content as the raw materials that make up the various materials, filtering the raw materials that make up the various materials, and performing distillation under conditions that minimize contamination as much as possible, such as by lining the inside of the equipment with Teflon (registered trademark).

In addition, as a method for reducing impurities such as metals in various materials other than the resist composition, in addition to the above-mentioned filter filtration, impurities may be removed using an adsorbent, or a combination of filter filtration and an adsorbent may be used. As the adsorbent, a known adsorbent may be used, for example, an inorganic adsorbent such as silica gel or zeolite, or an organic adsorbent such as activated carbon. In order to reduce impurities such as metals contained in various materials other than the resist composition, it is necessary to prevent the inclusion of metal impurities in the manufacturing process. Whether or not metal impurities have been sufficiently removed from the manufacturing equipment can be confirmed by measuring the content of metal components contained in the cleaning solution used to clean the manufacturing equipment.

An organic processing liquid such as a rinse liquid may contain a conductive compound to prevent breakdown of chemical liquid piping and various parts (filters, O-rings, tubes, etc.) due to static electricity buildup and subsequent static electricity discharge. The conductive compound is not particularly limited, but an example thereof is methanol. The amount added is not particularly limited, but from the viewpoint of maintaining favorable development characteristics or rinsing characteristics, it is preferably 10% by mass or less, and more preferably 5% by mass or less.
The chemical liquid piping may be made of stainless steel (SUS), or may be made of various piping coated with antistatic polyethylene, polypropylene, or fluororesin (polytetrafluoroethylene, perfluoroalkoxy resin, etc.). Similarly, the filter and O-ring may be made of antistatic polyethylene, polypropylene, or fluororesin (polytetrafluoroethylene, perfluoroalkoxy resin, etc.).

A method for improving the surface roughness of a pattern may be applied to the pattern formed by the method of the present invention. Examples of methods for improving the surface roughness of a pattern include a method of treating the pattern with a plasma of a gas containing hydrogen, as disclosed in International Publication No. 2014/002808. Other known methods include those described in JP 2004-235468 A, U.S. Patent Application Publication No. 2010/0020297 A, JP 2008-83384 A, and Proc. of SPIE Vol. 8328 83280N-1 "EUV Resist Curing Technique for LWR Reduction and Etch Selectivity Enhancement".

When the pattern to be formed is in the form of lines, the aspect ratio, calculated by dividing the pattern height by the line width, is preferably 2.5 or less, more preferably 2.1 or less, and even more preferably 1.7 or less.
When the pattern to be formed is a trench (groove) pattern or a contact hole pattern, the aspect ratio calculated by dividing the pattern height by the trench width or hole diameter is preferably 4.0 or less, more preferably 3.5 or less, and even more preferably 3.0 or less.

The pattern formation method of the present invention can also be used for forming guide patterns in DSA (Directed Self-Assembly) (see, for example, ACS Nano Vol. 4 No. 8 Pages 4815-4823).

Furthermore, the pattern formed by the above method can be used, for example, as a core material for the spacer process disclosed in JP-A-03-270227 and JP-A-2013-164509.

[Electronic device manufacturing method]
The present invention also relates to a method for manufacturing an electronic device, including the above-mentioned pattern formation method. Examples of the electronic device include those installed in electric and electronic devices (such as home appliances, OA (Office Automation), media-related devices, optical devices, and communication devices).

[Composition container]
The composition container of the present invention has a container and an actinic ray-sensitive or radiation-sensitive resin composition (resist composition) contained in the container.

[Storage container]
The container is not particularly limited, but it is preferable that the area in the container that comes into contact with the resist composition (for example, the inner wall of the container that contains the resist composition and/or the flow path for the resist composition) is made of a material mainly composed of a non-metal. Here, the term "main component" means that the main component constitutes 80 mass % or more of the area that comes into contact with a specific component.

As the material for the region that comes into contact with the resist composition in the storage container, a resin is preferred, and a polyolefin resin or a fluorine-based resin is more preferred, in order to suppress aggregation of photoacid generator B (corresponding to a photoacid generator that contains a polyvalent salt structure in its molecule) using moisture adhering to the above region as a nucleus, and to prevent contamination by elution from the storage container due to excessive affinity with the storage container.

Specific examples of storage containers in which the area that comes into contact with the resist composition is a fluororesin include the FluoroPure PFA composite drum manufactured by Entegris, and the containers described on page 4 of Published Japanese Translation of PCT International Publication No. 3-502677, page 3 of WO 2004/016526, and pages 9 and 16 of WO 99/46309.

As the material for the region that comes into contact with the resist composition in the container, one or more resins selected from the group consisting of polyolefin resins and fluorine atom-containing polyolefin resins are more preferable, in terms of further suppressing aggregation of photoacid generator B using moisture adhering to the above region as a nucleus.
As the polyolefin resin, high density polyethylene (HDPE) is preferred.
The fluorine atom-containing polyolefin resin is preferably perfluoroalkane (PFA) or polytetrafluoroethylene (PTFE).

As the storage container, containers described in U.S. Patent Application Publication No. 2015/0227049, Japanese Patent Application Publication No. 2015-123351 (JP 2015-123351), and Japanese Patent Application Publication No. 2017-13804 (JP 2017-13804), etc., can also be suitably used.

As for storage containers, those with a high degree of cleanliness inside the container and low elution of impurities for semiconductor applications can also be used suitably. Specific examples include the "Clean Bottle" series manufactured by Aicello Chemical Co., Ltd. and the "Pure Bottle" manufactured by Kodama Plastics Industry Co., Ltd.

It is preferable to wash the inside of the container before filling. There are no particular limitations on the liquid used for this washing, but it is preferable that the metal content be less than 0.001 parts per trillion by mass.

[Resist Composition]
The resist composition is as described above.

The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, processing contents, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the examples shown below.

[Various components of actinic ray- or radiation-sensitive resin composition]
[Acid-decomposable resin]
Resins A (Resins A-1 to A-20) shown in Tables 4 and 9 are shown below.
Resins A-1 to A-20 were synthesized in accordance with the synthesis method of Resin A-1 (Synthesis Example 1) described later. Table 1 shows the composition ratio (molar ratio; corresponding from left to right), weight average molecular weight (Mw), and dispersity (Mw/Mn) of each repeating unit shown later.
The weight average molecular weight (Mw) and dispersity (Mw/Mn) of Resins A-1 to A-20 were measured by GPC (carrier: tetrahydrofuran (THF)) (polystyrene equivalent amount). The composition ratio (mol % ratio) of the resins was measured by ^13C -NMR (nuclear magnetic resonance).

The structural formulas of resins A-1 to A-20 shown in Table 1 are shown below.

(Synthesis Example 1: Synthesis of Resin A-1)
Cyclohexanone (113 g) was heated to 80 ° C. under a nitrogen gas flow. While stirring this liquid, a mixed solution of a monomer represented by the following formula M-1 (25.5 g), a monomer represented by the following formula M-2 (31.6 g), cyclohexanone (210 g), and 2,2'-azobisisobutyric acid dimethyl [V-601, manufactured by Wako Pure Chemical Industries, Ltd.] (6.21 g) was dropped over 6 hours to obtain a reaction liquid. After the dropwise addition was completed, the reaction liquid was stirred at 80 ° C. for another 2 hours. The obtained reaction liquid was allowed to cool, and then reprecipitated with a large amount of methanol / water (mass ratio 9: 1), filtered, and the obtained solid was vacuum dried to obtain 52 g of resin A-1.

The weight average molecular weight (Mw: polystyrene equivalent) of the obtained resin A-1 determined by GPC (carrier: tetrahydrofuran (THF)) was 6,500, and the dispersity (Mw/Mn) was 1.52. The composition ratio measured by ¹³ C-NMR (nuclear magnetic resonance) was 50/50 in molar ratio.

[Photoacid generator]
<Photoacid Generator B>
The structures of photoacid generators B (compounds B-1 to B-24) shown in Tables 4 and 9 are shown below. Additionally, the structure of comparative photoacid generator B-25 shown in Tables 4 and 9 is shown below. Comparative photoacid generator B-25 does not fall under the category of compounds (photoacid generator B) selected from the group consisting of the above-mentioned compounds (I) to (III).

<Photoacid Generator C>
The structures of the photoacid generators C (compounds C-1 to C-21) shown in Tables 4 and 9 are shown below.

[Acid Diffusion Controller]
The structures of the acid diffusion controllers D (compounds D-1 to D-5) shown in Tables 4 and 9 are shown below.

[Hydrophobic resin and topcoat resin]
The hydrophobic resins (E-1 to E-11) shown in Tables 4 and 9 and the topcoat resins (PT-1 to PT-3) shown in Table 5 were synthesized.
Table 2 shows the molar ratios of repeating units, weight average molecular weights (Mw), and dispersities (Mw/Mn) of the hydrophobic resins shown in Tables 4 and 9 and the top coat resins shown in Table 5.
The weight average molecular weight (Mw) and dispersity (Mw/Mn) of the hydrophobic resins E-1 to E-11 and the topcoat resins PT-1 to PT-3 were measured by GPC (carrier: tetrahydrofuran (THF)) (polystyrene equivalent). The composition ratio (mol % ratio) of the resins was measured by ^13C -NMR (nuclear magnetic resonance).

The monomer structures used in the synthesis of hydrophobic resins E-1 to E-11 shown in Tables 4 and 9 and top coat resins PT-1 to PT-3 shown in Table 5 are shown below.

[Surfactant]
The surfactants shown in Tables 4 and 9 are as follows:
H-1: Megafac F176 (DIC Corporation, fluorosurfactant)
H-2: Megafac R08 (manufactured by DIC Corporation, fluorine and silicon-based surfactant)
H-3: PF656 (manufactured by OMNOVA, fluorosurfactant)

〔solvent〕
The solvents shown in Tables 4 and 9 are as follows.
F-1: Propylene glycol monomethyl ether acetate (PGMEA)
F-2: Propylene glycol monomethyl ether (PGME)
F-3: Propylene glycol monoethyl ether (PGEE)
F-4: Cyclohexanone F-5: Cyclopentanone F-6: 2-heptanone F-7: Ethyl lactate F-8: γ-butyrolactone F-9: Propylene carbonate

[Preparation of actinic ray- or radiation-sensitive resin composition and pattern formation: ArF immersion exposure]
[Preparation of actinic ray- or radiation-sensitive resin composition (1)]
<Actinic ray-sensitive or radiation-sensitive resin compositions Re-1 to Re-29, Re-31, and Re-33>
First, the acid-decomposable resin (resin A) was vacuum-dried at 15 mmHg and 60° C. for a predetermined time (the drying time for the acid-decomposable resin (resin A) was adjusted for each composition within the range of 2 to 12 hours so that the water content of each actinic ray-sensitive or radiation-sensitive resin composition was the water content shown in Table 3). Then, the components shown in Table 4 were mixed so that the solid content concentration was 4 mass%. Next, the resulting mixture was first filtered through a polyethylene filter having a pore size of 50 nm, then a nylon filter having a pore size of 10 nm, and finally a polyethylene filter having a pore size of 5 nm in this order to prepare actinic ray-sensitive or radiation-sensitive resin compositions (hereinafter also referred to as resin compositions) Re-1 to Re-29, Re-31, and Re-33. In the resin composition, the solid content means all components other than the solvent. Next, the resulting resin composition was sealed in a predetermined container (the types of containers are shown in Tables 6 and 7, respectively). The composition container containing the resin composition was left for 4 weeks in an environment of a temperature of 23° C. and a humidity of 60%. The resin composition that was sealed in the specified storage container and left for the specified period was used for pattern formation, which will be described later.

<Actinic ray-sensitive or radiation-sensitive resin compositions Re-30 and Re-32>
Resin compositions Re-30 and Re-32 were prepared in the same manner as resin compositions Re-1 to Re-29, Re-31, and Re-33, except that the acid-decomposable resin (resin A) was not vacuum-dried prior to mixing of each component. The obtained resin composition was then sealed in a predetermined container (the types of containers are shown in Tables 6 and 7, respectively). The composition container in which the resin composition was sealed was left for 4 weeks in an environment at a temperature of 23° C. and a humidity of 60%. The resin composition sealed in the predetermined storage container and aged for a predetermined period of time was used for pattern formation, which will be described later.

<Measurement of Moisture Content>
Immediately after preparation, the water content of each of the resin compositions was measured using a Karl Fischer moisture meter (MKC-510N manufactured by Kyoto Electronics Manufacturing Co., Ltd.) according to the following procedure.
Specifically, 10 mL of the resist composition was placed in a titration flask in the air at 23° C., and the water content was calculated using MKC-510N manufactured by Kyoto Electronics Manufacturing Co., Ltd. The results are shown in Table 3.

Table 4 is shown below.
In Table 4, the content (mass %) of each component means the content relative to the total solid content.

[Preparation of Topcoat Composition]
The various components contained in the topcoat composition shown in Table 5 are listed below.
<Resin>
As the resins shown in Table 5, resins PT-1 to PT-3 shown in Table 2 were used.
<Additives>
The structures of the additives shown in Table 5 are shown below.

<Surfactant>
As the surfactant shown in Table 5, the above-mentioned surfactant H-3 was used.

<Solvent>
The solvents shown in Table 5 are as follows:
FT-1: 4-methyl-2-pentanol (MIBC)
FT-2: n-decane FT-3: diisoamyl ether

<Preparation of Top Coat Composition>
The components shown in Table 5 are mixed so that the solid content concentration is 3 mass%, and then the resulting mixture is filtered in the order of a polyethylene filter having a pore size of 50 nm, a nylon filter having a pore size of 10 nm, and a polyethylene filter having a pore size of 5 nm, to prepare a top coat composition. The solid content here means all components other than the solvent. The obtained top coat composition is used in the examples.

[Pattern formation (1): ArF immersion exposure, organic solvent development]
A composition for forming an organic anti-reflective coating ARC29SR (manufactured by Brewer Science) was applied onto a silicon wafer and baked at 205°C for 60 seconds to form an anti-reflective coating having a thickness of 98 nm. On top of that, each resin composition shown in Table 4 (a resin composition sealed in a predetermined storage container and aged for a predetermined period of time) was applied thereon and baked at 100°C for 60 seconds to form a resist film (actinic ray-sensitive or radiation-sensitive film) having a thickness of 90 nm. In addition, in Examples 1-5, 1-6, and 1-7, a topcoat film was formed on the upper layer of the resist film (the type of topcoat composition used is shown in Table 6). The thickness of the topcoat film was 100 nm in all cases.
The resist film was exposed to light through a 6% halftone mask of a 1:1 line and space pattern with a line width of 45 nm using an ArF excimer laser immersion scanner (manufactured by ASML; XT1700i, NA 1.20, Dipole, outer sigma 0.950, inner sigma 0.850, Y deflection). Ultrapure water was used as the immersion liquid.
The exposed resist film was baked at 90° C. for 60 seconds, developed with n-butyl acetate for 30 seconds, rinsed with 4-methyl-2-pentanol for 30 seconds, and then spin-dried to obtain a negative pattern.

<Defect evaluation>
After forming the pattern with a line width of 45 nm, the distribution of defects on the silicon wafer was detected using UVision 5 (manufactured by AMAT), and the shape of the defects was observed using SEMVision G4 (manufactured by AMAT). The defects on the patterned wafer were observed as images such as those shown in Figures 1 and 2. The number of defects per silicon wafer was counted and evaluated according to the following evaluation criteria. The fewer the number of defects, the better the results.
(Evaluation criteria)
"S": The number of defects is 50 or less; "A": The number of defects is more than 50 and less than 200; "B": The number of defects is more than 200 and less than 300; "C": The number of defects is more than 300 and less than 400; "D": The number of defects is more than 400 and less than 500; "E": The number of defects is more than 500

<Evaluation Results>
The results of the above evaluation tests are shown in Table 6.
The storage containers listed in Table 6 are as follows.
"A": A container with an inner wall of the container section made of glass.
"B": A container whose inner wall is made of polyethylene (PE).
"C": A container whose inner wall is made of polytetrafluoroethylene (PTFE).
Moreover, the "amount ratio T" in Table 6 is expressed by the following formula (1X).
Formula (1X): Amount ratio T = content (mass %) of a compound selected from the group consisting of compounds (I) to (III) (corresponding to photoacid generator B) relative to the solid content in the composition / water content (mass %) relative to the total mass of the composition

As shown in Table 6, it is clear that the resist composition of the present invention can form a pattern with suppressed defects even after storage for a specified period of time.
Moreover, from a comparison of Examples 1-1 to 1-13 and Examples 1-16 to 1-19 (particularly, a comparison of Example 1-6 with Example 1-18, and Example 1-13 with Example 1-19), it is clear that the defect suppression performance of the formed pattern is more excellent when the quantitative ratio T represented by the above formula (1X) is 4.0 to 500.0. Furthermore, it is clear that the defect suppression performance of the formed pattern is more excellent when the water content is 0.50 mass % or less (preferably 0.03 to 0.30 mass %) with respect to the total mass of the composition.
Furthermore, from a comparison of Examples 1-1, 1-14, and 1-15, it is clear that when the inner wall of the storage portion of the storage container is made of one or more resins selected from the group consisting of polyolefin resins and fluorine atom-containing polyolefin resins, the defect suppression performance of the formed pattern is more excellent.
On the other hand, it is clear that the resist compositions of the comparative examples do not satisfy the desired requirements.

[Pattern formation (2): ArF immersion exposure, alkaline aqueous solution development]
A composition for forming an organic anti-reflective coating ARC29SR (manufactured by Brewer Science) was applied onto a silicon wafer and baked at 205°C for 60 seconds to form an anti-reflective coating having a thickness of 98 nm. On top of that, each resin composition shown in Table 4 (a resin composition sealed in a predetermined storage container and aged for a predetermined period of time) was applied and baked at 100°C for 60 seconds to form a resist film having a thickness of 90 nm. In addition, in Examples 2-3, 2-4, and 2-5, a topcoat film was formed on the upper layer of the resist film (the type of topcoat composition used is shown in Table 7). The thickness of the topcoat film was 100 nm in all cases.
The resist film was exposed to light through a 6% halftone mask of a 1:1 line and space pattern with a line width of 45 nm using an ArF excimer laser immersion scanner (manufactured by ASML; XT1700i, NA 1.20, Dipole, outer sigma 0.950, inner sigma 0.890, Y deflection). Ultrapure water was used as the immersion liquid.
The exposed resist film was baked at 90° C. for 60 seconds, developed with an aqueous solution of tetramethylammonium hydroxide (2.38% by mass) for 30 seconds, rinsed with pure water for 30 seconds, and then spin-dried to obtain a positive pattern.
The resulting positive pattern was subjected to the same <Defect Evaluation> as that performed on the negative pattern obtained in the above-mentioned [Pattern Formation (1): ArF immersion exposure, organic solvent development].

<Evaluation Results>
The results of the above evaluation tests are shown in Table 7.
The storage containers listed in Table 7 are as follows.
"A": A container with an inner wall of the container section made of glass.
"B": A container whose inner wall is made of polyethylene (PE).
"C": A container whose inner wall is made of polytetrafluoroethylene (PTFE).
Moreover, the "amount ratio T" in Table 7 is expressed by the following formula (1X).
Formula (1X): Amount ratio T = content (mass %) of the compound selected from the group consisting of compounds (I) to (III) (corresponding to photoacid generator B) relative to the solid content in the composition / water content (mass %) relative to the total mass of the composition

As shown in Table 7, it is clear that the resist composition of the present invention can form a pattern with suppressed defects even after storage for a specified period of time.
Moreover, it is clear from Examples 2-1 to 2-13 and Examples 2-16 to 2-18 that the defect suppression performance of the formed pattern is more excellent when the quantitative ratio T represented by the above formula (1X) is 4.0 to 500.0. Furthermore, it is clear that the defect suppression performance of the formed pattern is more excellent when the water content is 0.50 mass % or less (preferably 0.03 to 0.30 mass %) with respect to the total mass of the composition.
Furthermore, from a comparison of Examples 2-1, 2-14, and 2-15, it is clear that when the inner wall of the storage portion of the storage container is made of one or more resins selected from the group consisting of polyolefin resins and fluorine atom-containing polyolefin resins, the defect suppression performance of the formed pattern is superior.
On the other hand, it is clear that the resist compositions of the comparative examples do not satisfy the desired requirements.

[Preparation of actinic ray- or radiation-sensitive resin composition and pattern formation: EUV exposure]
[Preparation of actinic ray- or radiation-sensitive resin composition (2)]
<Actinic ray-sensitive or radiation-sensitive resin compositions Re-34 to Re-54, Re-56, and Re-58>
First, the acid-decomposable resin was vacuum-dried at 15 mmHg and 60° C. for a predetermined time (the drying time for the acid-decomposable resin (resin A) was adjusted for each composition within the range of 2 to 12 hours so that the water content of each actinic ray-sensitive or radiation-sensitive resin composition was the water content shown in Table 8). Then, each component shown in Table 9 was mixed so that the solid content concentration was 2 mass%. Next, the resulting mixture was first filtered through a polyethylene filter having a pore size of 50 nm, then a nylon filter having a pore size of 10 nm, and finally a polyethylene filter having a pore size of 5 nm in this order to prepare actinic ray-sensitive or radiation-sensitive resin compositions (hereinafter also referred to as resin compositions) Re-34 to Re-54, Re-56, and Re-58. In the resin composition, the solid content means all components other than the solvent. Next, the resulting resin composition was sealed in a predetermined container (the types of containers are shown in Tables 10 and 11, respectively). The composition container containing the resin composition was left for 4 weeks in an environment of a temperature of 23° C. and a humidity of 60%. The resin composition that was sealed in the specified storage container and left for the specified period was used for pattern formation, which will be described later.

<Actinic ray-sensitive or radiation-sensitive resin compositions Re-55 and Re-57>
Resin compositions Re-55 and Re-57 were prepared in the same manner as resin compositions Re-34 to Re-54, Re-56, and Re-58, except that the acid-decomposable resin (resin A) was not vacuum-dried prior to mixing of each component. The obtained resin composition was then sealed in a predetermined container (the types of containers are shown in Tables 10 and 11, respectively). The composition container in which the resin composition was sealed was left for 4 weeks in an environment at a temperature of 23° C. and a humidity of 60%. The resin composition sealed in the predetermined storage container and aged for a predetermined period of time was used for pattern formation described below.

<Measurement of Moisture Content>
Immediately after preparation, the water content of each of the resin compositions was measured using a Karl Fischer moisture meter (MKC-510N manufactured by Kyoto Electronics Manufacturing Co., Ltd.) according to the following procedure.
Specifically, 10 mL of the resist composition was placed in a titration flask in the air at 23° C., and the water content was calculated using MKC-510N manufactured by Kyoto Electronics Manufacturing Co., Ltd. The results are shown in Table 8.

Table 9 is shown below.
In Table 9, the content (mass%) of each component means the content relative to the total solid content.

[Pattern formation (3): EUV exposure, organic solvent development]
A composition for forming an underlayer film, AL412 (manufactured by Brewer Science), was applied onto a silicon wafer and baked at 205° C. for 60 seconds to form a 20 nm thick undercoat film. Each of the resin compositions shown in Table 8 (resin compositions sealed in a designated storage container and aged for a designated period of time) was applied thereon and baked at 100° C. for 60 seconds to form a 30 nm thick resist film.
The silicon wafer having the resist film thus obtained was subjected to pattern irradiation using an EUV exposure apparatus (Micro Exposure Tool, NA 0.3, Quadrupol, outer sigma 0.68, inner sigma 0.36, manufactured by Exitech). As a reticle, a mask with a line size of 20 nm and a line:space ratio of 1:1 was used.
The exposed resist film was baked at 90° C. for 60 seconds, developed with n-butyl acetate for 30 seconds, and then spin-dried to obtain a negative pattern.

<Defect evaluation>
After forming the pattern with a line width of 20 nm, the defect distribution on the silicon wafer was detected using UVision 5 (manufactured by AMAT), and the shape of the defects was observed using SEMVision G4 (manufactured by AMAT). The defects generated on the pattern wafer were observed as images such as those shown in Figures 1 and 2. The number of defects per silicon wafer was counted and evaluated according to the following evaluation criteria. The fewer the number of defects, the better the results.
(Evaluation criteria)
"S": The number of defects is 50 or less; "A": The number of defects is more than 50 and less than 200; "B": The number of defects is more than 200 and less than 300; "C": The number of defects is more than 300 and less than 400; "D": The number of defects is more than 400 and less than 500; "E": The number of defects is more than 500

<Evaluation Results>
The results of the above evaluation tests are shown in Table 10.
The storage containers listed in Table 10 are as follows.
"A": A container with an inner wall of the container section made of glass.
"B": A container whose inner wall is made of polyethylene (PE).
"C": A container whose inner wall is made of polytetrafluoroethylene (PTFE).
Moreover, the "amount ratio T" in Table 10 is expressed by the following formula (1X).
Formula (1X): Amount ratio T = content (mass %) of the compound selected from the group consisting of compounds (I) to (III) (corresponding to photoacid generator B) relative to the solid content in the composition / water content (mass %) relative to the total mass of the composition

As shown in Table 10, it is clear that the resist composition of the present invention can form a pattern with suppressed defects even after storage for a specified period of time.
In addition, from a comparison of Examples 3-1 to 3-9 and Examples 3-12 to 3-14, it is clear that the defect suppression performance of the formed pattern is more excellent when the quantitative ratio T represented by the above formula (1X) is 4.0 to 500.0. Furthermore, it is clear that the defect suppression performance of the formed pattern is more excellent when the water content is 0.50 mass% or less (preferably 0.03 to 0.30 mass%) with respect to the total mass of the composition.
Furthermore, from a comparison of Examples 3-1, 3-10, and 3-11, it is clear that when the inner wall of the storage portion of the storage container is made of one or more resins selected from the group consisting of polyolefin resins and fluorine atom-containing polyolefin resins, the defect suppression performance of the formed pattern is superior.
On the other hand, it is clear that the resist compositions of the comparative examples do not satisfy the desired requirements.

[Pattern formation (4): EUV exposure, alkaline aqueous solution development]
A composition for forming an underlayer film, AL412 (manufactured by Brewer Science), was applied onto a silicon wafer and baked at 205° C. for 60 seconds to form a 20 nm thick undercoat film. Each of the resin compositions shown in Table 11 (resin compositions sealed in a designated storage container and aged for a designated period of time) was applied thereon and baked at 100° C. for 60 seconds to form a 30 nm thick resist film.
The silicon wafer having the resist film thus obtained was subjected to pattern irradiation using an EUV exposure apparatus (Micro Exposure Tool, NA 0.3, Quadrupol, outer sigma 0.68, inner sigma 0.36, manufactured by Exitech). As a reticle, a mask with a line size of 20 nm and a line:space ratio of 1:1 was used.
The exposed resist film was baked at 90° C. for 60 seconds, developed with an aqueous solution of tetramethylammonium hydroxide (2.38% by mass) for 30 seconds, rinsed with pure water for 30 seconds, and then spin-dried to obtain a positive pattern.
The resulting positive pattern was subjected to the same <Defect Evaluation> as that performed on the negative pattern obtained in the above-mentioned [Pattern Formation (3): EUV Exposure, Organic Solvent Development].

<Evaluation Results>
The results of the above evaluation tests are shown in Table 11.
The storage containers listed in Table 11 are as follows.
"A": A container with an inner wall of the container section made of glass.
"B": A container whose inner wall is made of polyethylene (PE).
"C": A container whose inner wall is made of polytetrafluoroethylene (PTFE).
Moreover, the "amount ratio T" in Table 11 is expressed by the following formula (1X).
Formula (1X): Amount ratio T = content (mass %) of the compound selected from the group consisting of compounds (I) to (III) (corresponding to photoacid generator B) relative to the solid content in the composition / water content (mass %) relative to the total mass of the composition

As shown in Table 11, it is clear that the resist composition of the present invention can form a pattern with suppressed defects even after storage for a specified period of time.
In addition, from a comparison of Examples 4-1 to 4-9 and Examples 4-12 to 4-15, it is clear that the defect suppression performance of the formed pattern is more excellent when the quantitative ratio T represented by the above formula (1X) is 4.0 to 500.0. Furthermore, it is clear that the defect suppression performance of the formed pattern is more excellent when the water content is 0.50 mass% or less (preferably 0.03 to 0.30 mass%) with respect to the total mass of the composition.
Furthermore, from a comparison of Examples 4-1, 4-10, and 4-11, it is clear that when the inner wall of the storage portion of the storage container is made of one or more resins selected from the group consisting of polyolefin resins and fluorine atom-containing polyolefin resins, the defect suppression performance of the formed pattern is superior.
On the other hand, it is clear that the resist compositions of the comparative examples do not satisfy the desired requirements.

Claims (4)

A composition container having a container and an actinic ray-sensitive or radiation-sensitive resin composition contained in the container,
a material of a region in the container that comes into contact with the composition is at least one selected from the group consisting of polyolefin resins and fluorine atom-containing polyolefin resins;
The composition comprises a resin that decomposes under the action of an acid to increase its polarity;
A compound that generates an acid when irradiated with actinic rays or radiation;
A solvent ,
The compound that generates an acid upon irradiation with actinic rays or radiation includes one or more compounds selected from the group consisting of the following compounds (I) to (III):
The water content in the composition is 1.00% by mass or less based on the total mass of the composition,
A composition container , in which a quantitative ratio T represented by the following formula (1X) is 4.0 to 500.0:
Formula (1X): Amount ratio T=content (mass%) of the compound selected from the group consisting of the compound (I) to the compound (III) relative to the solid content in the composition/water content (mass%) relative to the total mass of the composition
Compound (I): a compound having each of the following structural moieties X and Y, which generates an acid containing the following first acidic moiety derived from the following structural moiety X and the following second acidic moiety derived from the following structural moiety Y upon irradiation with actinic rays or radiation; Structural moiety X: a structural moiety consisting of an anionic moiety A ₁ ^- and a cationic moiety M ₁ ⁺ , and which forms a first acidic moiety represented by HA ₁ upon irradiation with actinic rays or radiation; Structural moiety Y: a structural moiety consisting of an anionic moiety A ₂ ^- and a cationic moiety M ₂ ⁺ , and which forms a second acidic moiety represented by HA ₂ having a structure different from the first acidic moiety formed at the structural moiety X upon irradiation with actinic rays or radiation; provided that compound (I) satisfies the following condition I.
Condition I: Compound PI, which is obtained by replacing the cationic moiety M ₁ ⁺ in the structural moiety X and the cationic moiety M ₂ ⁺ in the structural moiety Y in compound (I) with H ⁺ , has an acid dissociation constant a1 derived from an acidic moiety represented by HA ₁ obtained by replacing the cationic moiety M ₁ ⁺ in the structural moiety X with H ⁺ , and an acid dissociation constant a2 derived from an acidic moiety represented by HA ₂ obtained by replacing the cationic moiety M ₂ ⁺ in the structural moiety Y with H ⁺ , and the acid dissociation constant a2 is greater than the acid dissociation constant a1.
Compound (II): A compound having two or more of the structural moieties X and the structural moiety Y, which generates an acid containing two or more of the first acidic moieties derived from the structural moiety X and the second acidic moiety derived from the structural moiety Y when irradiated with actinic rays or radiation. However, compound (II) satisfies the following condition II.
Condition II: Compound PII, which is obtained by replacing the cationic moiety M ₁ ⁺ in the structural moiety X and the cationic moiety M ₂ ⁺ in the structural moiety Y in compound (II) with H ⁺ , has an acid dissociation constant a1 derived from an acidic moiety represented by HA ₁ obtained by replacing the cationic moiety M ₁ ⁺ in the structural moiety X with H ⁺ , and an acid dissociation constant a2 derived from an acidic moiety represented by HA ₂ obtained by replacing the cationic moiety M ₂ ⁺ in the structural moiety Y with H ⁺ , and the acid dissociation constant a2 is greater than the acid dissociation constant a1.
Compound (III): A compound having two or more of the structural moieties X and the following structural moiety Z, which generates an acid containing two or more of the first acidic moieties derived from the structural moiety X and the structural moiety Z upon irradiation with actinic rays or radiation. Structural moiety Z: A nonionic organic moiety capable of neutralizing an acid. The composition container according to claim 1 , wherein the moisture content in the composition is 0.50% by mass or less with respect to the total mass of the composition. The composition container according to claim 1 or 2, wherein the water content in the composition is 0.30% by mass or less with respect to the total mass of the composition. The composition container according to any one of claims 1 to 3, wherein the water content in the composition is 0.03 to 0.30% by mass with respect to the total mass of the composition.