TWI900770B - Radiation-sensitive resin composition, resist pattern forming method and compound - Google Patents

Abstract

A radiation-sensitive resin composition comprises: a polymer having a structural unit containing an acid-dissociable group; and a compound having a cationic portion and a radiation-sensitive onium cation portion, wherein the cationic portion comprises an aromatic ring structure in which at least one hydrogen atom is substituted by a halogen atom or a halogen atom-containing group; and an anionic group-containing group bonded to the aromatic ring structure; and in the aromatic ring structure, the number of covalent bonds constituting the shortest atomic chain between a first atom bonded to the halogen atom or the halogen atom-containing group and a second atom bonded to the anionic group-containing group is 2 or less.

Description

Radiation-sensitive resin composition, resist pattern forming method and compound

The present invention relates to a radiation-sensitive resin composition, a method for forming an anti-etching pattern, and a compound.

The radiation-sensitive resin compositions used in microfabrication using lithography are irradiated with radiation, such as far ultraviolet light (e.g., ArF excimer lasers (wavelength 193 nm), KrF excimer lasers (wavelength 248 nm), electromagnetic waves (e.g., extreme ultraviolet (EUV) (wavelength 13.5 nm), and charged particle beams such as electron beams, to produce acid in the exposed areas. A chemical reaction catalyzed by this acid creates a difference in the dissolution rate of the developer between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

Radiation-sensitive resin compositions are required not only to have good sensitivity to exposure light such as extreme ultraviolet (EUV) and electron beams, but also to exhibit excellent line width roughness (LWR) performance.

In response to these requirements, research has been conducted on the types and molecular structures of polymers, acid generators, and other components used in radiation-sensitive resin compositions, and their combinations have also been studied in detail (see Japanese Patent Publication Nos. 2010-134279, 2014-224984, and 2016-047815). [Prior Art Literature] [Patent Literature]

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

[The problem that the invention aims to solve]

As resist patterns become increasingly smaller, the impact of slight variations in exposure and development conditions on resist pattern shape and defect formation becomes increasingly significant. Consequently, radiation-sensitive resin compositions with a wide process window (process margin) are required to absorb these slight variations in process conditions.

However, the conventional radiation-sensitive resin compositions cannot satisfy all of these requirements.

The present invention is based on the above-described circumstances and aims to provide a radiation-sensitive resin composition, a method for forming a resist pattern, and a compound capable of forming a resist pattern with good sensitivity to exposure light, excellent LWR performance, and a wide process window. [Means for Solving the Problem]

The invention achieved to solve the above-mentioned problems is a radiation-sensitive resin composition comprising: a polymer having a structural unit containing an acid-dissociable group (hereinafter also referred to as "[A] polymer"); and a compound having a cationic portion and a radiation-sensitive onium cation (hereinafter also referred to as "[Z] compound"), wherein the cationic portion has an aromatic ring structure in which at least one hydrogen atom is substituted with a halogen atom or a halogen atom-containing group, and an anionic group-containing group bonded to the aromatic ring structure; and in the aromatic ring structure, the number of covalent bonds constituting the shortest atomic chain between a first atom to which the halogen atom or halogen atom-containing group is bonded and a second atom to which the anionic group-containing group is bonded is 2 or less.

Another invention developed to solve the above-mentioned problem is a method for forming a resist pattern, comprising: directly or indirectly applying the radiation-sensitive resin composition to a substrate; exposing the resist film formed by the application; and developing the exposed resist film.

Another invention developed to solve the aforementioned problem is the "Z" compound. [Effects of the Invention]

The radiation-sensitive resin composition, resist pattern formation method, and compound of the present invention can form a resist pattern with good sensitivity to exposure light, excellent light-reduction (LWR) performance, and a wide process window. Therefore, these compositions are ideal for forming fine resist patterns during lithography steps for various electronic devices, including semiconductors and liquid crystal devices.

The radiation-sensitive resin composition, resist pattern forming method, and compound of the present invention are described in detail below.

<Radiation-Sensitive Resin Composition> The radiation-sensitive resin composition contains a polymer [A] and a compound [Z]. The radiation-sensitive resin composition typically contains an organic solvent (hereinafter also referred to as "[D] organic solvent"). The radiation-sensitive resin composition may also contain, as preferred components, a radiation-sensitive acid generator other than the [Z] compound (hereinafter also referred to as "[B] acid generator") and/or an acid diffusion controller other than the [Z] compound (hereinafter also referred to as "[C] acid diffusion controller"). The radiation-sensitive resin composition may also contain other optional components as long as they do not impair the effects of the present invention.

The radiation-sensitive resin composition, by containing the polymer [A] and the compound [Z], can form a resist pattern with good sensitivity to exposure light, excellent LWR performance, and a wide process window. The reason why the radiation-sensitive resin composition exhibits the above-described effect due to the inclusion of the above-described structure is not necessarily clear, but can be speculated as follows, for example. Specifically, it is believed that the [Z] compound contained in the radiation-sensitive resin composition has a cationic portion with a specific structure, which readily absorbs exposure light, thereby increasing the efficiency of acid generation due to exposure. As a result, the radiation-sensitive resin composition can form a resist pattern with good sensitivity to exposure light, excellent LWR performance, and a wide process window.

The radiation-sensitive resin composition can be prepared, for example, by mixing [A] the polymer and [Z] the compound, and optionally [B] the acid generator, [C] the acid diffusion control agent, [D] the organic solvent, and other optional components in a predetermined ratio, and filtering the resulting mixture, preferably through a membrane filter having a pore size of 0.20 μm or less.

Hereinafter, each component contained in the radiation-sensitive resin composition will be described.

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

The polymer [A] preferably further comprises a structural unit containing a phenolic hydroxyl group (hereinafter also referred to as "structural unit (II)"). The polymer [A] may further comprise other structural units other than structural unit (I) and structural unit (II) (hereinafter also referred to as "other structural units").

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

The lower limit of the polystyrene-equivalent weight average molecular weight (Mw) of polymer [A], as determined by gel permeation chromatography (GPC), is preferably 1,000, more preferably 3,000, and even more preferably 5,000. The upper limit of the Mw is preferably 50,000, more preferably 30,000, even more preferably 20,000, even more preferably 15,000, and particularly preferably 10,000. By setting the Mw of polymer [A] within this range, the coating properties of the radiation-sensitive resin composition can be improved. The Mw of polymer [A] can be adjusted, for example, by adjusting the type or amount of the polymerization initiator used in the synthesis.

The upper limit of the ratio of the Mw of the polymer [A] to the polystyrene-equivalent number average molecular weight (Mn) obtained by GPC (hereinafter also referred to as "dispersity" or "Mw/Mn") is preferably 2.50, more preferably 2.00, and further preferably 1.75. The lower limit of the ratio is generally 1.00, preferably 1.10, more preferably 1.20, and further preferably 1.30.

[Measurement Method for Mw and Mn] The Mw and Mn values of polymer [A] in this specification are values measured using gel permeation chromatography (GPC) under the following conditions. GPC columns: 2 Tosoh G2000HXL columns, 1 G3000HXL column, and 1 G4000HXL column Column temperature: 40°C Eluent: Tetrahydrofuran Flow rate: 1.0 mL/min Sample concentration: 1.0 mass% Sample injection volume: 100 μL Detector: Differential refractometer Standard material: Monodisperse polystyrene

[A] The polymer can be synthesized by, for example, polymerizing monomers providing each structural unit using a known method.

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

[Structural Unit (I)] Structural Unit (I) is a structural unit containing an acid-dissociable group. An "acid-dissociable group" is a group that replaces a hydrogen atom in a carboxyl group, a hydroxyl group, or the like, and is dissociated by the action of an acid to provide a carboxyl group, a hydroxyl group, or the like. Upon exposure to light, the acid-dissociable group dissociates from the acid generated by the [Z] compound or the [B] acid generator, thereby creating a difference in the solubility of the [A] polymer in the developer between the exposed and unexposed areas, thereby forming a resist pattern. The [A] polymer may contain one or more structural units (I).

Examples of structural unit (I) include the structural units represented by the following formulas (I-1) to (I-3) (hereinafter also referred to as "structural units (I-1) to (I-3)"). Furthermore, for example, in the following formula (I-1), -C( ^RX )( ^RY )( ^RZ ) bonded to the etheric oxygen atom derived from the carboxyl group corresponds to an acid-dissociable group.

[Chemistry 1]

In the formula (I-1), formula (I-2) and formula (I-3), ^RT is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

In the formula (I-1), ^RX is a substituted or unsubstituted monovalent alkyl group having 1 to 20 carbon atoms. ^RY and ^RZ are each independently a monovalent alkyl group having 1 to 20 carbon atoms, or a portion of a saturated alicyclic structure having 3 to 20 ring members formed by these groups bonded together with the carbon atoms to which they are bonded.

In formula (I-2), ^RA is a hydrogen atom. ^RB and ^RC are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. ^RD is a divalent hydrocarbon group having 1 to 20 carbon atoms that, together with the carbon atoms to which ^RA , ^RB, and ^RC are bonded, forms an unsaturated alicyclic structure having 4 to 20 ring members.

In the above formula (I-3), R ^U and R ^V are each independently a hydrogen atom or a monovalent alkyl group having 1 to 20 carbon atoms, and R ^W is a monovalent alkyl group having 1 to 20 carbon atoms, or is a part of an aliphatic cyclic structure having 3 to 20 ring members formed by R ^U and R ^V being bonded to each other and together with the carbon atoms to which they are bonded, or is a part of an aliphatic heterocyclic structure having 4 to 20 ring members formed by R ^U and R ^W being bonded to each other and together with the carbon atom to which R ^U is bonded and the oxygen atom to which R ^W is bonded.

The term "carbon number" refers to the number of carbon atoms that make up a group. The term "ring member number" refers to the number of atoms that make up the ring structure. In the case of polycyclic rings, it refers to the number of atoms that make up the polycyclic ring.

"Hydrocarbon groups" include chain alkyl groups, alicyclic alkyl groups, and aromatic alkyl groups. These "alkyl groups" may be saturated or unsaturated. A "chain alkyl group" refers to a alkyl group consisting solely of a chain structure without a ring structure, and includes both straight chain alkyl groups and branched chain alkyl groups. An "alicyclic alkyl group" refers to a alkyl group containing only an alicyclic structure as a ring structure and not an aromatic ring structure, and includes both monocyclic alicyclic alkyl groups and polycyclic alicyclic alkyl groups. However, a alkyl group need not contain only an alicyclic structure; a chain structure may be contained in part. An "aromatic alkyl group" refers to a alkyl group containing an aromatic ring structure. It does not necessarily have to contain only an aromatic ring structure and may also contain a chain structure or an aliphatic ring structure as part of its ring structure.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by ^RX , ^RY , ^RZ , ^RB , ^RC , ^RU , ^RV or ^RW include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl; alkenyl groups such as ethenyl, propenyl, butenyl, and 2-methylpropane-1-en-1-yl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

Examples of the monovalent alicyclic alkyl group having 3 to 20 carbon atoms include monocyclic alicyclic saturated alkyl groups such as cyclopentyl and cyclohexyl; polycyclic alicyclic saturated alkyl groups such as norbornyl, adamantyl, tricyclodecanyl, and tetracyclododecyl; monocyclic alicyclic unsaturated alkyl groups such as cyclopentenyl and cyclohexenyl; and polycyclic alicyclic unsaturated alkyl groups such as norbornyl, tricyclodecanyl, and tetracyclododecenyl.

Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthracenyl; and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthracenylmethyl.

Examples of the substituents of the alkyl group represented by ^RX include halogen atoms such as fluorine atoms, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, and acyloxy groups.

As a saturated alicyclic structure with 3 to 20 ring members formed by R ^Y and R ^Z together with the carbon atoms to which they are bonded, and R ^U and R ^V is bonded to each other and to the carbon atoms to which it is bonded to form an alicyclic structure having 3 to 20 ring members, for example: a monocyclic saturated alicyclic structure such as a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, and a cyclohexane structure; a polycyclic saturated alicyclic structure such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure; a monocyclic unsaturated alicyclic structure such as a cyclopropene structure, a cyclobutene structure, a cyclopentene structure, and a cyclohexene structure; a polycyclic unsaturated alicyclic structure such as a norbornene structure, a tricyclodecene structure, and a tetracyclododecene structure; and the like.

Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by ^RD include groups obtained by removing one hydrogen atom from the groups exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by ^RX , ^RY , ^RZ , ^RB , ^RC , ^RU , ^RV or ^RW .

Examples of the unsaturated alicyclic structure having 4 to 20 ring members formed by the carbon atoms to which ^RD , ^RA , ^RB , and ^RC are respectively bonded include monocyclic unsaturated alicyclic structures such as cyclobutene structure, cyclopentene structure, and cyclohexene structure; and polycyclic unsaturated alicyclic structures such as norbornene structure.

Examples of the aliphatic heterocyclic structure having 4 to 20 ring members formed by R ^U and R ^W bonding to each other, together with the carbon atom to which R ^U is bonded and the oxygen atom to which R ^W is bonded include heterocyclic structures containing saturated oxygen such as oxycyclobutane structures, oxycyclopentane structures, and oxycyclohexane structures; and heterocyclic structures containing unsaturated oxygen such as oxycyclobutene structures, oxycyclopentene structures, and oxycyclohexene structures.

From the viewpoint of improving the copolymerizability of the monomers of the structural unit (I), ^RT is preferably a hydrogen atom or a methyl group.

R ^X is preferably a substituted or unsubstituted chain alkyl group or a substituted or unsubstituted aromatic alkyl group, more preferably an unsubstituted chain alkyl group or a substituted or unsubstituted aromatic alkyl group, further preferably an unsubstituted alkyl group or a substituted or unsubstituted aryl group, further preferably a methyl group, an ethyl group, an isopropyl group, a t-butyl group or a phenyl group.

^RY and ^RZ are preferably part of a saturated alicyclic structure having 3 to 20 ring members formed by these groups and the carbon atoms to which they are bonded. The saturated alicyclic structure is preferably a cyclopentane structure, a cyclohexane structure, or a tetracyclododecane structure.

R ^B is preferably a hydrogen atom.

^RC is preferably a hydrogen atom or a chain hydrocarbon group, more preferably a hydrogen atom or an alkyl group, further preferably a hydrogen atom or a methyl group.

The unsaturated alicyclic structure having 4 to 20 ring members formed by the carbon atoms to which ^RD , ^RA , ^RB , and ^RC are respectively bonded is preferably a monocyclic unsaturated alicyclic structure, more preferably a cyclopentene structure or a cyclohexene structure.

The structural unit (I) is preferably the structural unit (I-1) or the structural unit (I-2).

As the structural unit (I-1), for example, the structural units represented by the following formulas (I-1-1) to (I-1-6) (hereinafter also referred to as "structural units (I-1-1) to (I-1-6)") are preferred.

[Chemistry 2]

In the above formulas (I-1-1) to (I-1-6), ^RT has the same meaning as in the above formula (I-1).

As the structural unit (I-2), the structural units represented by the following formulas (I-2-1) and (I-2-2) (hereinafter also referred to as "structural units (I-2-1) and (I-2-2)") are preferred.

[Chemistry 3]

In the above formulas (I-2-1) and (I-2-2), ^RT has the same meaning as in the above formula (I-2).

The lower limit of the content of the structural unit (I) in the polymer [A] is preferably 30 mol%, more preferably 40 mol%, based on all the structural units constituting the polymer [A]. The upper limit of the content is preferably 80 mol%, more preferably 70 mol%.

[Structural Unit (II)] Structural Unit (II) is a structural unit containing a phenolic hydroxyl group. The term "phenolic hydroxyl group" is not limited to hydroxyl groups directly bonded to a benzene ring, but refers to all hydroxyl groups directly bonded to an aromatic ring. [A] The polymer may have one or more structural units (II).

When polymer [A] contains structural unit (II), the hydrophilicity of the resist film can be enhanced, allowing for appropriate adjustment of solubility in developer solutions. Furthermore, the adhesion of the resist pattern to the substrate can be improved. Furthermore, when extreme ultraviolet (EUV) or electron beam radiation is used as the radiation in the exposure step of the resist pattern formation method described below, the sensitivity to the exposure light can be further enhanced. Therefore, when polymer [A] contains structural unit (II), the radiation-sensitive resin composition can be particularly preferably used as a radiation-sensitive resin composition for EUV exposure or electron beam exposure.

Examples of the structural unit (II) include the structural units represented by the following formulas (II-1) to (II-19) (hereinafter also referred to as "structural units (II-1) to (II-19)").

[Chemistry 4]

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

As the structural unit (II), preferably, it is the structural unit (II-1), the structural unit (II-3), or a combination thereof.

When the polymer [A] contains the structural unit (II), the lower limit of the content of the structural unit (II) relative to all the structural units in the polymer [A] is preferably 20 mol%, more preferably 30 mol%. The upper limit of the content is preferably 60 mol%, more preferably 50 mol%.

[Other Structural Units] Examples of other structural units include: a structural unit containing an alcoholic hydroxyl group (hereinafter also referred to as "structural unit (III)"); a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof (hereinafter also referred to as "structural unit (IV)"); and the like. [A] The polymer may have one or more other structural units.

(Structural Unit (III)) Structural Unit (III) is a structural unit containing an alcoholic hydroxyl group. When the polymer [A] contains structural unit (III), its solubility in the developer solution can be appropriately adjusted.

Examples of the structural unit (III) include a structural unit containing a hydroxy alicyclic alkyl group, a structural unit containing a hydroxy chain alkyl group, and a structural unit containing a hydroxy fluorinated chain alkyl group. More specifically, the structural unit represented by the following formula can be cited.

[Chemistry 5]

In the formula, ^RL2 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

As the structural unit (III), a structural unit containing a hydroxyl alicyclic alkyl group or a structural unit containing a hydroxyl fluorinated chain alkyl group is preferred. Among the structural units containing a hydroxyl fluorinated chain alkyl group, a structural unit containing a hydroxyl fluorinated alkyl group is more preferred.

When the polymer [A] contains the structural unit (III), the lower limit of the content of the structural unit (III) is preferably 1 mol%, more preferably 5 mol%, relative to all the structural units constituting the polymer [A]. The upper limit of the content is preferably 40 mol%, more preferably 30 mol%.

(Structural Unit (IV)) Structural Unit (IV) is a structural unit comprising a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof. Furthermore, Structural Unit (IV) is a structural unit different from Structural Unit (III). If it further comprises an alcoholic hydroxyl group in addition to a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof, it is classified as Structural Unit (IV).

Examples of the structural unit (IV) include the structural unit represented by the following formula.

[Chemistry 6]

[Chemistry 7]

[Chemistry 8]

[Chemistry 9]

In the formula, ^RL1 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

As the structural unit (IV), a structural unit containing a lactone structure is preferred.

When the polymer [A] contains the structural unit (IV), the lower limit of the content of the structural unit (IV) is preferably 1 mol%, more preferably 5 mol%, relative to all the structural units constituting the polymer [A]. The upper limit of the content is preferably 60 mol%, more preferably 50 mol%.

<[Z] Compound> The [Z] compound is a compound having an anionic portion (hereinafter also referred to as the "anionic portion (X)") and a radiation-sensitive onium cation portion (hereinafter also referred to as the "cationic portion (Y)"). The radiation-sensitive resin composition may contain one or more [Z] compounds.

Depending on the type of anionic moiety (X), the compound [Z] has the following functions in the radiation-sensitive resin composition: generating an acid upon exposure to radiation, or controlling the diffusion of an acid generated by exposure from an acid generator (described later) [B] within the resist film, thereby controlling undesirable chemical reactions in non-exposed areas. In other words, depending on the type of anionic moiety (X), the compound [Z] functions as a radiation-sensitive acid generator or an acid diffusion controller in the radiation-sensitive resin composition.

When the [Z] compound functions as a radiation-sensitive acid generator, the radiation may be, for example, the same exposure light as exemplified in the exposure step of the resist pattern forming method described below. The acid generated from the [Z] compound by irradiation with the radiation dissociates acid-dissociable groups contained in the structural unit (I) of the [A] polymer, generating carboxyl groups, etc., thereby causing a difference in the solubility of the resist film in the developer between the exposed and unexposed areas, thereby forming a resist pattern.

When the [Z] compound functions as an acid diffusion control agent, it generates acid in the exposed areas, increasing the solubility or insolubility of the [A] polymer in the developer solution, thereby suppressing surface roughness in the exposed areas after development. Meanwhile, in the unexposed areas, the compound exerts its high acid-trapping function, brought about by anions, acting as a quencher, trapping acid diffused from the exposed areas. This means that since the compound functions as a quencher only in the unexposed areas, the contrast of the deprotection reaction is improved, resulting in enhanced resolution.

Hereinafter, each structure of the compound [Z] will be described.

<Anionic Moiety (X)> The anionic moiety (X) comprises an aromatic ring structure in which at least one hydrogen atom is substituted with a halogen atom or a halogen atom-containing group (hereinafter also referred to as "aromatic ring structure (a)"), and an anionic group bonded to the aromatic ring structure (a) (hereinafter also referred to as "anionic group (b)").

[Aromatic Ring Structure (a)] In the aromatic ring structure (a), at least one hydrogen atom in the aromatic ring (hereinafter also referred to as "aromatic ring (a1)") is substituted with a halogen atom or a halogen atom-containing group (hereinafter, the halogen atom and the halogen atom-containing group are collectively referred to as "halogen atom-containing group (a2)"). In other words, the aromatic ring structure (a) comprises the aromatic ring (a1) and the halogen atom-containing group (a2) bonded to the aromatic ring (a1). The aromatic ring structure (a) may also have a substituent other than the halogen atom-containing group (a2) (hereinafter, also referred to as "substituent (a3)"). The anionic portion (X) may have one or more aromatic ring structures (a), and preferably has one or two aromatic ring structures (a).

In the aromatic ring structure (a), the total number of halogen atoms constituting the one or more halogen-containing groups (a2) is preferably 2 or more, more preferably 3 or more. In this case, a resist pattern with a wider process window can be formed. The upper limit of the total number of halogen atoms is, for example, 10.

(Aromatic Ring (a1)) Aromatic ring (a1) is an aromatic ring that provides aromatic ring structure (a). Examples of aromatic ring (a1) include aromatic hydrocarbon rings having 6 to 30 ring members and aromatic heterocyclic rings having 5 to 30 ring members.

Examples of the aromatic hydrocarbon ring having 6 to 30 ring members include a benzene ring, a naphthalene ring, a phenanthrene ring, and anthracene ring.

Examples of the aromatic heterocyclic ring having 5 to 30 ring members include heterocyclic rings containing oxygen atoms such as furan ring, pyran ring, benzofuran ring, and benzopyran ring; and heterocyclic rings containing nitrogen atoms such as pyrrole ring, pyridine ring, pyrimidine ring, and indole ring.

The aromatic ring (a1) is preferably an aromatic hydrocarbon ring having 6 to 30 ring members, more preferably a benzene ring or a naphthalene ring, and even more preferably a benzene ring.

(Halogen Atom-Containing Group (a2)) The halogen atom-containing group (a2) is a halogen atom or a halogen atom-containing group. The term "halogen atom-containing group" refers to a group containing a halogen atom. The aromatic ring structure (a) may have one or more halogen atom-containing groups (a2).

Examples of the halogen atom in the halogen atom-containing group (a2) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a fluorine atom or an iodine atom is preferred, and a fluorine atom is more preferred.

Examples of the halogen-containing group in the halogen-containing group (a2) include alkyl halides having 1 to 20 carbon atoms and pentafluorothiohydrogen groups. "Alkyl halides" refer to groups in which some or all of the hydrogen atoms in an alkyl group are substituted with halogen atoms. Among these, fluorinated alkyl groups or pentafluorothiohydrogen groups are preferred, perfluoroalkyl groups or pentafluorothio hydrogen groups are more preferred, and trifluoromethyl groups or pentafluorothio hydrogen groups are even more preferred.

In the aromatic ring structure (a), the number of covalent bonds constituting the shortest atomic chain between the first atom to which the halogen-containing group (a2) is bonded and the second atom to which the anionic group (b) described later is bonded (hereinafter also referred to as the "shortest chain covalent bond number") is 2 or less. While not intended to be limiting, it is speculated that the inclusion of this specific structure in the anionic portion (X) of the [Z] compound facilitates absorption of exposure light, improving the efficiency of acid generation due to exposure. As a result, the radiation-sensitive resin composition can form a resist pattern having good sensitivity to exposure light, excellent LWR performance, and a wide process window.

Regardless of the type of covalent bond between two adjacent atoms, the number of covalent bonds is counted as "1." For example, when the shortest-chain covalent bond number is 2, it means that a third atom is present between the first and second atoms, while when the shortest-chain covalent bond number is 1, it means that the first and second atoms are adjacent.

The number of the shortest chain covalent bonds is 2 or 1, preferably 2. When the aromatic ring structure (a) has a plurality of halogen atom-containing groups (a2), there are a plurality of atoms corresponding to the first atom, but the number of the shortest chain covalent bonds between at least one of the first atoms and the second atom is 2 or less.

In the aromatic ring structure (a), the halogen atom-containing group (a2) is preferably not bonded to an atom having 3 or more shortest chain covalent bonds, and more preferably not bonded to an atom having 3 or more shortest chain covalent bonds.

(Substituent (a3)) Examples of substituent (a3) include hydroxyl, carboxyl, cyano, nitro, alkoxy, alkoxycarbonyl, alkoxycarbonyloxy, acyl, and acyloxy groups. Among these, hydroxyl and alkoxy groups are preferred, and hydroxyl and methoxy groups are more preferred.

Examples of the aromatic ring structure (a) include a 3-fluorobenzene structure, a 3,5-difluorobenzene structure, a 3-trifluoromethylbenzene structure, a 3,5-bis(trifluoro)benzene structure, a 3-fluoro-4-hydroxybenzene structure, a 3-fluoro-5-trifluoromethylbenzene structure, and a 3-pentafluorothiothiobenzene structure. In these examples, the carbon atom at position 1 of the benzene ring is the first atom.

[Anionic Group (b)] Anionic Group (b) is a group that is bonded to the aromatic ring structure (a) and has an anionic group (hereinafter also referred to as "anionic group (b1)"). "Anionic Group (b)" does not include a group consisting solely of anionic groups.

The anionic group-containing group (b) preferably further has a (thio)acetal structure (hereinafter also referred to as "(thio)acetal structure (b2)"). The anionic group-containing group (b) preferably further has an alicyclic structure (hereinafter also referred to as "alicyclic structure (b3)"). The anionic group-containing group (b) may also have a structure other than the anionic group (b1), (thio)acetal structure (b2), and alicyclic structure (b3).

(Anionic Group (b1)) The anionic group (b1) is, for example, a monovalent anionic group, and specific examples thereof include a sulfonic acid anionic group (-SO ₃ ^- ) and a carboxylic acid anionic group (-COO ^- ).

As described above, the [Z] compound functions as a radiation-sensitive acid generator or an acid diffusion control agent in the radiation-sensitive resin composition, depending on the type of the anion portion (X). More specifically, the [Z] compound functions as a radiation-sensitive acid generator or an acid diffusion control agent in the radiation-sensitive resin composition, depending on the type of the anion group (b1). For example, when the anion group (b1) is a sulfonate anion, the [Z] compound functions as a radiation-sensitive acid generator, whereas when the anion group (b1) is a carboxylate anion, the [Z] compound functions as an acid diffusion control agent. Hereinafter, the anion portion (X) in which the anion group (b1) is a sulfonate anion group may be referred to as "anion portion (X-1)", and the anion portion (X) in which the anion group (b1) is a carboxylate anion group may be referred to as "anion portion (X-2)".

When the anionic portion (X) is the anionic portion (X-1), the compound [Z] functions as a radiation-sensitive acid generator in the radiation-sensitive resin composition. In this case, the radiation-sensitive resin composition preferably contains an acid diffusion controller [C]. Furthermore, in this case, the radiation-sensitive resin composition may contain an acid generator other than the compound [Z] ([B] acid generator).

When the anionic portion (X) is the anionic portion (X-2), the compound [Z] functions as an acid diffusion controller in the radiation-sensitive resin composition. In this case, the radiation-sensitive resin composition preferably contains an acid generator [B]. Furthermore, in this case, the radiation-sensitive resin composition may contain an acid diffusion controller other than the compound [Z] ([C] acid diffusion controller).

The anion group (b1) is preferably a sulfonate anion group. In other words, the anion portion (X) is preferably an anion portion (X-1).

When the anionic portion (X) is the anionic portion (X-1), the anionic group-containing group (b) preferably has a partial structure represented by the following formula (1).

[Chemistry 10]

In the formula (1), ^R1 and ^R2 are each independently a hydrogen atom, a halogen atom, a monovalent alkyl group having 1 to 20 carbon atoms, or a monovalent alkyl halide group having 1 to 20 carbon atoms. n is an integer from 1 to 10. When n is 2 or greater, multiple ^R1s are the same or different, and multiple ^R2s are the same or different. * represents a bonding site with a portion of the anionic group-containing group (b) other than the structure represented by the formula (1).

Examples of the halogen atom in R ¹ and R ² include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms in ^R1 and ^R2 include the same groups as exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by ^RX , RY, ^RZ , ^RB , ^RC , ^RU , ^{RV ,} or ^RV in the above-mentioned formulae (I-1) to (I-3).

Examples of the monovalent halogenated alkyl group having 1 to 20 carbon atoms in R ¹ and R ² include groups in which a part or all of the hydrogen atoms in the above-mentioned alkyl group are substituted with halogen atoms.

Preferably, at least one of ^R1 and ^R2 is a halogen atom or a monovalent alkyl halide having 1 to 20 carbon atoms. The halogen atom is preferably a fluorine atom. The alkyl halide is preferably a fluorinated alkyl group, more preferably a perfluoroalkyl group, and still more preferably a trifluoromethyl group.

As n, 1 to 5 is preferred, 1 to 3 is more preferred, and 2 is further preferred.

Furthermore, when the anionic group-containing group (b) has an alicyclic structure (b3) described below, it is preferred that the partial structure is bonded to the alicyclic structure (b3).

((Thio)acetal structure (b2)) The term "(thio)acetal structure" encompasses both "acetal structure" and "thioacetal structure." Furthermore, "(thio)acetal structure" encompasses both "chain (thio)acetal structure" and "cyclic (thio)acetal structure." Furthermore, "thioacetal structure" encompasses both "monothioacetal structure" and "dithioacetal structure."

As the (thio)acetal structure, a cyclic (thio)acetal structure is preferred from the perspective of structure, and an acetal structure is preferred from the perspective of constituent atoms. That is, as the (thio)acetal structure, a cyclic (thio)acetal structure is preferred, and a cyclic acetal structure is more preferred.

Examples of cyclic (thio)acetal structures include the structure represented by the following formula (2).

[Chemistry 11]

In the formula (2), ^X1 and ^X2 are each independently an oxygen atom or a sulfur atom. ^R3 is a (m+2)-valent alkyl group having 1 to 20 carbon atoms. m is 1 or 2. ** represents a bonding site with a portion of the anionic group-containing group (b) other than the structure represented by the formula (2).

Furthermore, regarding the classification of the cyclic (thio)acetal structure, in the formula (2), when ^{both X1} and ^X2 are oxygen atoms, it is a "cyclic acetal structure", and when at least one of ^X1 and ^X2 is a sulfur atom, it is a "cyclic thioacetal structure". Furthermore, when one of ^X1 and ^X2 is an oxygen atom and the other is a sulfur atom, it is a "cyclic monothioacetal structure", and when ^{both X1} and ^X2 are sulfur atoms, it is a "cyclic dithioacetal structure".

As ^X1 and ^X2 , it is preferred that at least one of ^X1 and ^X2 is an oxygen atom, and it is more preferred that both ^X1 and ^X2 are oxygen atoms.

Examples of the (m+2)-valent alkyl group having 1 to 20 carbon atoms represented by R ³ include groups formed by removing (m+2) hydrogen atoms from alkanes such as methane, ethane, n-propane, and n-butane. R ³ is preferably a alkyl group having a carbon number of 5 or 7 ring members in the cyclic (thio)acetal structure represented by the above formula (2). That is, R ³ is preferably a group formed by removing (m+2) hydrogen atoms from ethane or n-butane. The term "ring member number of the cyclic (thio)acetal structure" refers to the number of atoms in the ring structure constituting the cyclic (thio)acetal structure.

The (thio)acetal structure (b2) is preferably bonded to the aromatic ring structure (a). In other words, when the anionic group (b) has the (thio)acetal structure (b2), the aromatic ring structure (a) in the anionic portion (X) is preferably bonded to the (thio)acetal structure (b2) in the anionic group (b). In this case, the atom to which the (thio)acetal structure (b2) in the aromatic ring structure (a) is bonded becomes the first atom when counting the number of the shortest chain covalent bonds.

(Alicyclic structure (b3)) Examples of the alicyclic structure (b3) include: monocyclic saturated alicyclic structures such as cyclopropane structure, cyclobutane structure, cyclopentane structure, and cyclohexane structure; polycyclic saturated alicyclic structures such as norbornane structure, adamantane structure, tricyclodecane structure, and tetracyclododecane structure; monocyclic unsaturated alicyclic structures such as cyclopropene structure, cyclobutene structure, cyclopentene structure, and cyclohexene structure; and polycyclic unsaturated alicyclic structures having 3 to 20 ring members such as norbornene structure, tricyclodecene structure, and tetracyclododecene structure.

The alicyclic structure (b3) is preferably a saturated alicyclic structure, more preferably a polycyclic saturated alicyclic structure, and still more preferably a norbornane structure.

Furthermore, the alicyclic structure (b3) preferably shares a carbon atom or a portion of a carbon chain with the (thio)acetal structure (b2). For example, when the alicyclic structure (b3) is a norbornane structure, embodiments can be exemplified in which a portion of the carbon chain constituting the norbornane structure is shared with a portion of the carbon chain constituting the (thio)acetal structure (b2). In this case, ^R3 in the formula (2) is a group formed by removing three hydrogen atoms from an alicyclic structure having 3 to 20 ring members.

As the anion part (X-1), for example, a structure represented by the following formula (3) is preferable.

[Chemistry 12]

In the formula (3), R ¹ , R ^{2 ,} and n have the same meanings as in the formula (1). X ¹ and X ² have the same meanings as in the formula (2). R ^3′ is a group formed by removing three hydrogen atoms from the alicyclic structure (b3). Ar is a group formed by removing (q+r+1) hydrogen atoms from the aromatic ring (a1). ^{R 4} is a halogen atom-containing group (a2). q is an integer from 1 to 5. ^{R 5} is a substituent (a3). r is an integer from 0 to 3. p is 1 or 2. When p is 2, multiple Ar, R ^{4 ,} and R ⁵ are the same or different. R ⁶ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

R ⁶ is preferably a hydrogen atom, a chain hydrocarbon group having 1 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, and more preferably a hydrogen atom, an alkyl group, or a phenyl group.

As the anion portion (X-1), structures represented by the following formulas (3-1) to (3-19) (hereinafter also referred to as "anion portion (X-1-1) to anion portion (X-1-19)") are preferred, and anion portion (X-1-1) to anion portion (X-1-12) are more preferred.

[Chemistry 13]

<Cationic Moiety (Y)> Examples of the cationic moiety (Y) include a monovalent cation represented by the following formula (r-a) (hereinafter also referred to as "cationic moiety (Y-1)"), a monovalent cation represented by the following formula (r-b) (hereinafter also referred to as "cationic moiety (Y-2)"), and a monovalent cation represented by the following formula (r-c) (hereinafter also referred to as "cationic moiety (Y-3)").

[Chemistry 14]

In the above formula (ra), b1 is an integer from 0 to 4. When b1 is 1, ^RB1 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. When b1 is 2 or greater, multiple ^RB1s are the same or different and are monovalent organic groups, hydroxyl groups, nitro groups, or halogen atoms having 1 to 20 carbon atoms, or are part of a ring structure having 4 to 20 ring members formed by combining these groups with the carbon chain to which they are bonded. ^b2 is an integer from 0 to 4. When b2 is 1, RB2 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. When b2 is 2 or more, multiple R ^{B2 groups} are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom, or are part of a ring structure having 4 to 20 ring members formed by combining these groups with the carbon chain to which they are bonded. R ^B3 and R ^B4 are each independently a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom, or represent a single bond formed by combining these groups. b3 is an integer from 0 to 11. When b3 is 1, R ^B5 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. When b3 is 2 or greater, multiple ^{RB5 groups} are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom, or are part of a ring structure having 4 to 20 ring members formed by combining these groups with the carbon chain to which they are bonded. _nb1 is an integer from 0 to 3.

In the formula (rb), b4 is an integer from 0 to 9. When b4 is 1, ^RB6 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. When b4 is 2 or more, multiple ^RB6 groups are the same or different and are monovalent organic groups having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom, or are part of a ring structure having 4 to 20 ring members formed by combining these groups with the carbon chain to which they are bonded. b5 is an integer from 0 to 10. When b5 is 1, ^RB7 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. When b5 is 2 or greater, multiple ^{RB7 groups} are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom, or are part of a ring structure having 3 to 20 ring members formed by combining these groups with the carbon atom or carbon chain to which they are bound. _nb3 is an integer from 0 to 3. ^RB8 is a single bond or a divalent organic group having 1 to 20 carbon atoms. _nb2 is an integer from 0 to 2.

In the above formula (rc), b6 is an integer from 0 to 5. When b6 is 1, ^RB9 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. When b6 is 2 or greater, multiple ^RB9s are the same or different and are monovalent organic groups, hydroxyl groups, nitro groups, or halogen atoms having 1 to 20 carbon atoms, or are part of a ring structure having 4 to 20 ring members formed by combining these groups with the carbon chain to which they are bonded. b7 is an integer from 0 to 5. When b7 is 1, ^RB10 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. When b7 is 2 or greater, multiple ^{RB10 groups} are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom, or are part of a ring structure having 4 to 20 ring members formed by combining these groups with the carbon chain to which they are bonded.

The term "organic group" refers to a group containing at least one carbon atom.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by ^RB1 , ^RB2 , ^RB3 , ^RB4 , ^RB5 , ^RB6 , ^RB7 , ^RB9 , or ^RB10 include: a monovalent alkyl group having 1 to 20 carbon atoms; a group (α) containing a divalent heteroatom-containing group between the carbon atoms of the alkyl group; a group (β) in which a part or all of the hydrogen atoms contained in the alkyl group or the group (α) are substituted with a monovalent heteroatom-containing group; and a group (γ) in which the alkyl group, the group (α), or the group (β) are combined with a divalent heteroatom-containing group.

Examples of the heteroatom constituting the monovalent or divalent heteroatom-containing group include oxygen, nitrogen, sulfur, phosphorus, silicon, and halogen atoms. Examples of the halogen atom include fluorine, chlorine, bromine, and iodine.

Examples of divalent groups containing a heteroatom include -O-, -CO-, -S-, -CS-, -NR'-, and groups formed by combining two or more of these groups (e.g., -COO-, -CONR'-, etc.). R' represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R' include the same groups as exemplified above for ^RA .

Examples of the divalent organic group represented by ^RB8 include groups obtained by removing one hydrogen atom from the groups exemplified as the monovalent organic group having 1 to 20 carbon atoms.

^RB3 and ^RB4 are preferably hydrogen atoms or single bonds formed by these atoms.

b1 and b2 are preferably 0 to 2, more preferably 0 or 1, and further preferably 0. b3 is preferably 0 to 2, more preferably 0 or 1, and further preferably 0. n _b1 is preferably 0 or 1, and further preferably 0.

The cation portion (Y) is preferably the cation portion (Y-1), more preferably a triphenylcathium cation.

As the [Z] compound, a compound in which the anionic portion (X) and the cationic portion (Y) are appropriately combined can be used.

When the [Z] compound functions as a radiation-sensitive acid generator, the lower limit of the content of the [Z] compound in the radiation-sensitive resin composition is preferably 1 part by mass, more preferably 5 parts by mass, and even more preferably 10 parts by mass, relative to 100 parts by mass of the [A] polymer. The upper limit of the content is preferably 60 parts by mass, more preferably 50 parts by mass, and even more preferably 40 parts by mass.

When the [Z] compound functions as an acid diffusion controller, the lower limit of the content of the [Z] compound in the radiation-sensitive resin composition is preferably 1 mol%, more preferably 5 mol%, and even more preferably 10 mol%, relative to 100 mol% of the [B] acid generator. The upper limit of the content is preferably 100 mol%, more preferably 50 mol%, and even more preferably 30 mol%.

The compound [Z] can be synthesized, for example, by the method described in the Examples below.

<[B] Acid Generator> The [B] acid generator is a radiation-sensitive acid generator other than the [Z] compound. The [B] acid generator is a compound that generates an acid upon exposure to radiation. In particular, when the [Z] compound contained in the radiation-sensitive resin composition functions as an acid diffusion control agent, the radiation-sensitive resin composition preferably contains the [B] acid generator. In this case, the acid generated from the [B] acid generator upon irradiation with radiation dissociates the acid-dissociable groups contained in the structural unit (I) of the [A] polymer, generating carboxyl groups, etc., thereby creating a difference in the solubility of the resist film in the developer between the exposed and unexposed areas, thereby forming a resist pattern. The radiation-sensitive resin composition may contain one or more [B] acid generators.

Examples of the [B] acid generator include onium salt compounds, N-sulfonyloxyimide compounds, sulfonimide compounds, halogen-containing compounds, and diazoketone compounds.

Examples of the onium salt compound include coronium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts.

Specific examples of the acid generator [B] include the compounds described in paragraphs 0080 to 0113 of Japanese Patent Application Laid-Open No. 2009-134088.

When the radiation-sensitive resin composition contains an acid generator [B], the lower limit of the amount of the acid generator [B] in the radiation-sensitive resin composition is preferably 5 parts by mass, more preferably 10 parts by mass, per 100 parts by mass of the polymer [A]. The upper limit of the amount is preferably 60 parts by mass, more preferably 50 parts by mass.

<[C] Acid Diffusion Control Agent> A [C] acid diffusion control agent is an acid diffusion control agent other than the [Z] compound. In particular, when the [Z] compound contained in the radiation-sensitive resin composition functions as a radiation-sensitive acid generator, the radiation-sensitive resin composition preferably contains a [C] acid diffusion control agent. In this case, the [C] acid diffusion control agent exerts the effect of controlling the diffusion of acid generated from the [Z] compound during exposure into the resist film and suppressing undesirable chemical reactions in non-exposed areas. The radiation-sensitive resin composition may contain one or more [C] acid diffusion control agents.

Examples of [C] acid diffusion control agents include nitrogen-containing compounds and compounds that become sensitive to light and generate weak acids (hereinafter referred to as "photodegradable bases") upon exposure. [C] acid diffusion control agents are preferably photodegradable bases.

Examples of nitrogen-containing compounds include amine compounds such as tripentylamine and trioctylamine; amide-containing compounds such as formamide and N,N-dimethylacetamide; urea compounds such as urea and 1,1-dimethylurea; and nitrogen-containing heterocyclic compounds such as pyridine, N-(undecylcarbonyloxyethyl)morpholine, and N-tert-pentyloxycarbonyl-4-hydroxypiperidine.

Examples of photodegradable bases include compounds composed of radiation-sensitive onium cations and weak acid anions. The photodegradable base generates acid in the exposed areas, increasing the solubility or insolubility of polymer [A] in the developer solution, thereby suppressing surface roughness in the exposed areas after development. Meanwhile, in the unexposed areas, the anions exert their high acid-scavenging function, acting as a quencher and trapping acid diffused from the exposed areas. This means that since the quencher functions only in the unexposed areas, the contrast of the deprotection reaction is improved, resulting in enhanced resolution.

Examples of the radiation-sensitive onium cation include the same cations as those exemplified as the monovalent radiation-sensitive onium cation in the section <[Z] compound>. Among them, the triphenylphosphine cation is preferred.

Examples of the weak acid anion include salicylate anion and 10-camphorsulfonate anion.

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

When the radiation-sensitive resin composition contains a [C] acid diffusion controller, the lower limit of the content of the [C] acid diffusion controller in the radiation-sensitive resin composition is preferably 1 mol%, more preferably 5 mol%, and even more preferably 10 mol%, relative to 100 mol% of the [Z] compound or the [B] acid generator. The upper limit of the content is preferably 100 mol%, more preferably 50 mol%, and even more preferably 30 mol%.

<[D] Organic Solvent> The radiation-sensitive resin composition typically contains [D] an organic solvent. The [D] organic solvent is not particularly limited as long as it can dissolve or disperse at least the [A] polymer and the [Z] compound, as well as any other optional components as needed.

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

Examples of alcohol-based solvents include aliphatic monoalcohol-based solvents having 1 to 18 carbon atoms, such as 4-methyl-2-pentanol and n-hexanol; alicyclic monoalcohol-based solvents having 3 to 18 carbon atoms, such as cyclohexanol; polyol-based solvents having 2 to 18 carbon atoms, such as 1,2-propylene glycol; and polyol-based partial ether-based solvents having 3 to 19 carbon atoms, such as propylene glycol 1-monomethyl ether.

Examples of the ether solvent include dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, diamyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; and aromatic ring-containing ether solvents such as diphenyl ether and anisole.

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

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

Examples of ester solvents include monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; lactone solvents such as γ-butyrolactone and valerolactone; polyol carboxylic acid ester solvents such as propylene glycol acetate; polyol partial ether carboxylic acid ester solvents such as propylene glycol monomethyl ether acetate; polycarboxylic acid diester solvents such as diethyl oxalate; and carbonate solvents such as dimethyl carbonate and diethyl carbonate.

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

As the organic solvent [D], an alcohol solvent, an ester solvent, or a combination thereof is preferred, and a C3-19 polyol partial ether solvent, a lactone solvent, a polyol partial ether carboxylate solvent, or a combination thereof is more preferred, and propylene glycol 1-monomethyl ether, γ-butyrolactone, propylene glycol monomethyl ether acetate, or a combination thereof is further preferred.

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

<Other Optional Ingredients> Examples of other optional ingredients include surfactants. The radiation-sensitive resin composition may also contain one or more other optional ingredients.

<Resist Pattern Formation Method> This resist pattern formation method includes: directly or indirectly applying a radiation-sensitive resin composition to a substrate (hereinafter referred to as the "coating step"); exposing the resist film formed by the coating step (hereinafter referred to as the "exposure step"); and developing the exposed resist film (hereinafter referred to as the "development step"). In this resist pattern formation method, the radiation-sensitive resin composition is used as the radiation-sensitive resin composition.

According to the resist pattern forming method, by using the radiation-sensitive resin composition as the radiation-sensitive resin composition in the coating step, a resist pattern having good sensitivity to exposure light, excellent LWR performance, and a wide process window can be formed.

The following describes the steps involved in forming the resist pattern.

[Coating Step] In this step, a radiation-sensitive resin composition is applied directly or indirectly to the substrate. This forms an anti-etching film directly or indirectly on the substrate.

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

Examples of substrates include silicon wafers, silicon dioxide-coated wafers, and aluminum-coated wafers, among others. Alternatively, the substrate may be one that has undergone a pre-treatment such as hydrophobization with hexamethyldisilazane (HMDS) (hereinafter referred to as "HMDS"). Furthermore, an example of indirectly applying the radiation-sensitive resin composition to a substrate is applying the radiation-sensitive resin composition onto an antireflection film formed on the substrate. Examples of such antireflection films include organic or inorganic antireflection films disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Application Laid-Open No. 59-93448.

Examples of coating methods include spin coating (spin coating), cast coating, and roll coating. After coating, a pre-bake (PB) (hereinafter referred to as "PB") may be performed as needed to volatilize the solvent in the coating film. The lower limit of the PB temperature is preferably 60°C, more preferably 80°C. The upper limit of the PB temperature is preferably 150°C, more preferably 140°C. The lower limit of the PB time is preferably 5 seconds, more preferably 10 seconds. The upper limit of the PB time is preferably 600 seconds, more preferably 300 seconds. The lower limit of the average thickness of the formed anti-etching film is preferably 10 nm, more preferably 20 nm. The upper limit of the average thickness is preferably 1,000 nm, more preferably 500 nm.

[Exposure Step] In this step, the resist film formed in the coating step is exposed to light. Exposure is performed by irradiating the film with exposure light through a photomask (or, optionally, an immersion medium such as water). Examples of exposure light include visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), electromagnetic waves such as X-rays and gamma rays, and charged particle beams such as electron beams and alpha rays, depending on the line width of the target pattern. Among these, far ultraviolet light, EUV, or electron beam are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV (wavelength 13.5 nm), or electron beam are more preferred, ArF excimer laser light, EUV, or electron beam are further preferred, and EUV or electron beam is particularly preferred.

After the exposure, a post-exposure bake (PEB) (hereinafter referred to as "PEB") is preferably performed. In the exposed portions of the resist film, the acid generated by the [Z] compound or the [B] acid generator promotes the dissociation of the acid-dissociable groups of the [A] polymer, etc. This PEB can increase the difference in solubility in the developer between the exposed and unexposed areas. The lower limit of the PEB temperature is preferably 50°C, more preferably 80°C, and even more preferably 100°C. The upper limit of the PEB temperature is preferably 180°C, more preferably 130°C. The lower limit of the PEB time is preferably 5 seconds, more preferably 10 seconds, and even more preferably 30 seconds. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds, and even more preferably 100 seconds.

[Developing Step] In this step, the exposed resist film is developed to form a desired resist pattern. After development, the film is typically rinsed with a rinse solution such as water or alcohol and then dried. The developing method in this step can be either alkaline or organic solvent.

In the case of alkaline development, examples of the developer used for development include alkaline aqueous solutions prepared by dissolving at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia water, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH) (hereinafter also referred to as "TMAH"), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, a TMAH aqueous solution is preferred, and a 2.38 mass% TMAH aqueous solution is more preferred.

In the case of organic solvent development, examples of developer solutions include organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents; and solutions containing these organic solvents. Examples of the organic solvent include one or more of the solvents listed as [D] organic solvents in the section "Radiation-sensitive resin composition." Of these, ester solvents and ketone solvents are preferred. Ester solvents are preferably acetate solvents, and n-butyl acetate is more preferred. Ketone solvents are preferably chain ketones, and 2-heptanone is more preferred. The lower limit of the content of the organic solvent in the developer is preferably 80 mass%, more preferably 90 mass%, further preferably 95 mass%, and particularly preferably 99 mass%. Examples of components other than the organic solvent in the developer include water and silicone oil.

Examples of developing methods include: immersing the substrate in a tank filled with developer for a predetermined period of time (immersion method); utilizing surface tension to deposit developer on the substrate surface and allowing it to remain there for a predetermined period of time to develop (puddle method); spraying developer onto the substrate surface (spray method); and continuously applying developer onto a rotating substrate while scanning a developer dispensing nozzle at a predetermined speed (dynamic dispensing method).

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

<Compound> This compound is described as compound [Z] in the <Radiation-sensitive resin composition> section. This compound can be preferably used as a component of the radiation-sensitive resin composition. [Examples]

The present invention will be described in detail below based on the following examples, but the present invention is not limited to these examples. The following describes the measurement methods of various physical properties.

[Weight Average Molecular Weight (Mw), Number Average Molecular Weight (Mn), and Dispersity (Mw/Mn)] [A] The Mw and Mn of a polymer are measured according to the conditions described in [Mw and Mn Determination Methods]. The dispersity (Mw/Mn) of a polymer is calculated based on the Mw and Mn measurement results.

<Synthesis of Polymer [A]> Monomers represented by the following formulas (M-1) to (M-13) (hereinafter also referred to as "monomers (M-1) to (M-13)") were used to synthesize polymer [A]. In the following synthesis examples, unless otherwise specified, parts by mass refers to the value when the total mass of the monomers used is assumed to be 100 parts by mass, and mole % refers to the value when the total molar number of the monomers used is assumed to be 100 mole %.

[Chemistry 15]

[Synthesis Example 1-1] Synthesis of Polymer (A-1) Monomers (M-1) and (M-3) were dissolved in propylene glycol 1-monomethyl ether (200 parts by mass) at a molar ratio of 40/60. Next, 6 mol% of azobisisobutyronitrile (AIBN) was added as an initiator to prepare a monomer solution. Separately, propylene glycol 1-monomethyl ether (100 parts by mass) was added to an empty reaction vessel and heated to 85°C while stirring. The prepared monomer solution was then added dropwise over 3 hours, followed by further heating at 85°C for 3 hours and a polymerization reaction for a total of 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to room temperature.

The cooled polymerization solution was added to hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered and isolated. The filtered white powder was washed twice with 100 parts by mass of hexane relative to the polymerization solution, filtered and isolated, and dissolved in propylene glycol 1-monomethyl ether (300 parts by mass). Methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were then added, and a hydrolysis reaction was carried out at 70°C for 6 hours while stirring. After the hydrolysis reaction was completed, the residual solvent was distilled off, and the resulting solid was dissolved in acetone (100 parts by mass). The resin was then added dropwise to 500 parts by mass of water to solidify. The resulting solid was filtered and separated. The solid was then dried at 50°C for 12 hours to synthesize a white powdered polymer (A-1). The polymer (A-1) had an Mw of 5,700 and an Mw/Mn ratio of 1.61.

[Synthesis Examples 1-2 to 1-10] Synthesis of Polymers (A-2) to (A-10) Polymers (A-2) to (A-10) were synthesized in the same manner as in Synthesis Example 1-1, except that the monomers were used in the types and proportions shown in Table 1 below.

Table 1 below shows the types and ratios of monomers contributing to the various structural units of the polymers [A] obtained in Synthesis Examples 1-1 to 1-10, as well as their Mw and Mw/Mn values. In Table 1, "-" indicates that the corresponding monomer was not used. Furthermore, monomers (M-1) and (M-2) were deacetylated by hydrolysis to provide structural units derived from p-hydroxystyrene and m-hydroxystyrene, respectively.

[Table 1] [A] Polymer Provides a unit cell of structural unit (I) Provide a unit cell of structural unit (II) Provides units for other structural units Physical properties Kind Usage ratio (mol%) Kind Usage ratio (mol%) Kind Usage ratio (mol%) Mw Mw/Mn Synthesis example 1-1 A-1 M-3 60 M-1 40 - - 5700 1.61 Synthesis example 1-2 A-2 M-4 60 M-1 40 - - 5800 1.64 Synthesis Example 1-3 A-3 M-5 60 M-1/M-2 30/10 - - 6100 1.65 Synthesis Example 1-4 A-4 M-6 60 M-1 40 - - 6200 1.50 Synthesis Example 1-5 A-5 M-7 60 M-1 40 - - 5500 1.54 Synthesis Example 1-6 A-6 M-8 60 M-1 40 - - 5400 1.53 Synthesis Example 1-7 A-7 M-9 60 M-1 40 - - 6000 1.67 Synthesis Example 1-8 A-8 M-3 60 M-1 30 M-10 10 6900 1.70 Synthesis Example 1-9 A-9 M-3 60 M-1 30 M-11 10 6800 1.65 Synthesis Example 1-10 A-10 M-4/M-12 40/15 - - M-13 45 8800 1.50

<Synthesis of Compound [Z]> [Synthesis Example 2-1] Synthesis of Compound (Z-1) In a reaction vessel, 45.0 mmol of the compound represented by the following formula (S-1), 45.0 mmol of 3,3'-difluorobenzophenone, and 4.5 mmol of p-toluenesulfonic acid (p-TsOH) were dissolved in 150 ml of toluene. A Dean-Stark tube was placed in the reaction vessel, and the solution was stirred under reflux for 10 hours. After cooling to room temperature, saturated aqueous sodium bicarbonate solution was added to terminate the reaction. Ethyl acetate was added for extraction, and the organic layer was separated. The resulting organic layer was dried over anhydrous sodium sulfate, and the solvent was removed. Purification using a silica gel column yielded a compound represented by the following formula (S-2) (hereinafter also referred to as "Compound (S-2)") with a yield of 87%.

26.0 mmol of compound (S-2) was dissolved in a mixture of acetonitrile and water (1:1 (mass ratio)) to prepare a 1 M solution. 52.0 mmol of sodium dithionite and 78.0 mmol of sodium bicarbonate were added, and the mixture was reacted at 70°C for 4 hours. The reaction product was extracted with acetonitrile, and the solvent was distilled off. A mixture of acetonitrile and water (3:1 (mass ratio)) was added to prepare a 0.5 M solution. 50.0 mmol of hydrogen peroxide and 2.9 mmol of sodium tungstate were added to this solution, and the mixture was heated and stirred at 50°C for 7 hours. The reaction product was extracted with acetonitrile, and the solvent was distilled off to obtain the compound represented by the following formula (S-3) (hereinafter also referred to as "compound (S-3)"). To compound (S-3), 26.0 mmol of triphenylphosphine bromide (TPS ^{+ Br-} ) was added, followed by a mixture of water and dichloromethane (1:3 (mass ratio)) to prepare a 0.5 M solution. After stirring at room temperature for 1 hour, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over anhydrous sodium sulfate, and the solvent was distilled off. Purification using a silica gel column yielded the compound represented by the following formula (Z-1) (hereinafter also referred to as "Compound (Z-1)"). The synthesis scheme of Compound (Z-1) is shown below.

[Chemistry 16]

[Synthesis Examples 2-2 to 2-12] Synthesis of Compounds (Z-2) to (Z-12) Compounds represented by the following formulas (Z-2) to (Z-12) (hereinafter also referred to as "Compounds (Z-2) to (Z-12)") were synthesized in the same manner as in Synthesis Example 2-1, except that the precursors were appropriately selected.

[Chemistry 17]

<Preparation of Radiation-Sensitive Resin Composition> The following lists [B] acid generator, [C] acid diffusion control agent, and [D] organic solvent used in the preparation of the radiation-sensitive resin composition. In the following Examples and Comparative Examples, unless otherwise specified, parts by mass refers to the mass of the polymer [A] used as 100 parts by mass, and mole % refers to the molar amount of the acid generator [B] used as 100 mole %.

([B] Acid Generator) [B] Acid generators used were compounds (Z-1) to (Z-12) and compounds represented by the following formulas (b-1) to (b-2) (hereinafter also referred to as "compounds (b-1) to (b-2)").

[Chemistry 18]

([C] Acid Diffusion Control Agent) As the [C] acid diffusion control agent, compounds represented by the following formulas (C-1) to (C-3) (hereinafter also referred to as "acid diffusion control agents (C-1) to (C-3)") were used.

[Chemistry 19]

([D] Organic Solvent) As [D] Organic Solvent, the following organic solvents (D-1) to (D-3) were used. (D-1): Propylene glycol monomethyl ether acetate (D-2): Propylene glycol 1-monomethyl ether (D-3): γ-Butyrolactone

[Example 1] Preparation of Radiation-Sensitive Resin Composition (R-1) [A] 100 parts by mass of polymer (A-1), [B] 20 parts by mass of compound (Z-1), [C] 20 mol% of acid diffusion controller (C-1), and [D] organic solvents: 4,800 parts by mass of organic solvent (D-1) and 2,000 parts by mass of organic solvent (D-2) were mixed. The resulting mixture was filtered through a membrane filter with a pore size of 0.20 μm to prepare radiation-sensitive resin composition (R-1).

[Examples 2 to 21 and Comparative Examples 1 to 2] Preparation of Radiation-Sensitive Resin Compositions (R-2) to (R-21) and Radiation-Sensitive Resin Compositions (CR-1) to (CR-2) Radiation-sensitive resin compositions (R-2) to (R-21) and radiation-sensitive resin compositions (CR-1) to (CR-2) were prepared in the same manner as in Example 1, except that the types and amounts of the components shown in Table 2 were used.

[Table 2] Radiation-sensitive resin composition [A] Polymer [B] Acid generator [C] Acid diffusion control agent [D]Organic solvent Kind Content (weight) Kind Content (weight) Kind Content ratio (mol%) Kind Content (weight) Example 1 R-1 A-1 100 Z-1 20 C-1 20 D-1/D-2 4800/2000 Example 2 R-2 A-1 100 Z-2 20 C-1 20 D-1/D-2 4800/2000 Example 3 R-3 A-1 100 Z-3 20 C-1 20 D-1/D-2 4800/2000 Example 4 R-4 A-1 100 Z-4 20 C-1 20 D-1/D-2 4800/2000 Example 5 R-5 A-1 100 Z-5 20 C-1 20 D-1/D-2 4800/2000 Example 6 R-6 A-1 100 Z-6 20 C-1 20 D-1/D-2 4800/2000 Example 7 R-7 A-1 100 Z-7 20 C-1 20 D-1/D-2 4800/2000 Example 8 R-8 A-1 100 Z-8 20 C-1 20 D-1/D-2 4800/2000 Example 9 R-9 A-1 100 Z-9 20 C-1 20 D-1/D-2 4800/2000 Example 10 R-10 A-1 100 Z-10 20 C-1 20 D-1/D-2 4800/2000 Example 11 R-11 A-1 100 Z-11 20 C-1 20 D-1/D-2 4800/2000 Example 12 R-12 A-1 100 Z-12 20 C-1 20 D-1/D-2 4800/2000 Example 13 R-13 A-2 100 Z-7 20 C-1 20 D-1/D-2 4800/2000 Example 14 R-14 A-3 100 Z-7 20 C-1 20 D-1/D-2 4800/2000 Example 15 R-15 A-4 100 Z-7 20 C-1 20 D-1/D-2 4800/2000 Example 16 R-16 A-5 100 Z-7 20 C-1 20 D-1/D-2 4800/2000 Example 17 R-17 A-6 100 Z-7 20 C-1 20 D-1/D-2 4800/2000 Example 18 R-18 A-7 100 Z-7 20 C-2 20 D-1/D-2 4800/2000 Example 19 R-19 A-8 100 Z-7 20 C-1 20 D-1/D-2 4800/2000 Example 20 R-20 A-9 100 Z-7 20 C-1 20 D-1/D-2 4800/2000 Comparative example 1 CR-1 A-1 100 b-1 20 C-1 20 D-1/D-2 4800/2000 Comparative example 2 CR-2 A-1 100 b-2 20 C-1 20 D-1/D-2 4800/2000 Example 21 R-21 A-10 100 Z-7 12 C-3 3.0 D-1/D-2/D-3 2240/960/30

<Resist Pattern Formation> Using a spin coater (Tokyo Electron's "CLEAN TRACK ACT12"), the radiation-sensitive resin compositions prepared in Examples 1-20 and Comparative Examples 1-2 were applied to a 12-inch silicon wafer with an average thickness of 20 nm (Brewer Science's "AL412") formed on the surface. After a 60-second pre-bake (PB) at 130°C and a 30-second cooling period at 23°C, a resist film with an average thickness of 50 nm was formed. Next, the resist film was exposed to EUV light using an ASML NXE3300, NA = 0.33, illumination conditions: Conventional s = 0.89, and a mask imecDEFECT32FFR02. Following exposure, the resist film underwent a post-exposure bake (PEB) at 110°C for 60 seconds. Subsequently, development was performed at 23°C for 30 seconds using a 2.38% by mass aqueous TMAH solution as an alkaline developer, forming a positive 32 nm line and space pattern.

<Evaluation> The sensitivity, LWR performance, and process window of each of the resist patterns formed above were evaluated using the following methods. A scanning electron microscope (Hitachi High-Tech's CG-4100) was used to measure the resist pattern length. The evaluation results are shown in Table 3 below.

[Sensitivity] In the resist pattern formation, the exposure required to form a 32 nm line and space pattern was defined as the optimal exposure, and this optimal exposure was defined as Eop (unit: mJ/cm ² ). Regarding sensitivity, a smaller Eop value indicates better sensitivity.

[LWR Performance] Using the scanning electron microscope, observe the formed resist pattern from above. Measure the line width at a total of 50 points at random locations. Calculate the 3-sigma value based on the distribution of these measured values and define this as the LWR (unit: nm). Regarding LWR performance, smaller LWR values indicate less line jitter and better quality.

[Process Window] The term "process window" refers to the range of resist dimensions within which patterns can be formed without bridging defects or pattern collapse. Using a mask that forms 32 nm lines and spaces (1L/1S), patterns are formed at exposures ranging from low to high. Typically, defects such as bridging between patterns are visible at low exposures, while defects such as pattern collapse are visible at high exposures. The difference between the maximum and minimum resist dimensions at which these defects are not visible is defined as the critical dimension (CD) margin (unit: nm). A larger CD margin indicates a wider and better process window.

[Table 3] Radiation-sensitive resin composition Eop (mJ/cm ² ) LWR (nm) CD margin (nm) Example 1 R-1 29 3.8 31 Example 2 R-2 28 3.9 31 Example 3 R-3 28 3.9 31 Example 4 R-4 30 3.8 32 Example 5 R-5 30 3.8 33 Example 6 R-6 30 3.8 31 Example 7 R-7 30 3.6 33 Example 8 R-8 29 3.8 33 Example 9 R-9 27 4.0 32 Example 10 R-10 29 3.9 32 Example 11 R-11 29 3.9 31 Example 12 R-12 30 3.8 32 Example 13 R-13 29 3.8 32 Example 14 R-14 28 3.8 32 Example 15 R-15 30 3.8 33 Example 16 R-16 28 3.8 31 Example 17 R-17 30 3.8 31 Example 18 R-18 29 3.8 32 Example 19 R-19 29 3.7 33 Example 20 R-20 29 3.8 33 Comparative example 1 CR-1 32 4.0 30 Comparative example 2 CR-2 29 4.2 28 [Industrial Availability]

The radiation-sensitive resin composition, resist pattern formation method, and compound of the present invention can form a resist pattern with good sensitivity to exposure light, excellent light-reduction (LWR) performance, and a wide process window. Therefore, these compositions are ideal for forming fine resist patterns during lithography steps for various electronic devices, including semiconductors and liquid crystal devices.

without

without

Claims (11)

A radiation-sensitive resin composition comprises: a polymer having structural units containing acid-dissociable groups; and a compound having an anionic portion and a radiation-sensitive onium cation; wherein the anionic portion comprises an aromatic ring structure in which at least one hydrogen atom is substituted with a fluorine atom or a fluorine-containing group; and an anionic group bonded to the aromatic ring structure; and in the aromatic ring structure, the number of covalent bonds constituting the shortest atomic chain between a first atom bonded to the fluorine atom or the fluorine-containing group and a second atom bonded to the anionic group is 2 or less. The radiation-sensitive resin composition according to claim 1, wherein the anion contained in the anion-containing group is a sulfonate anion or a carboxylate anion. The radiation-sensitive resin composition according to claim 2, wherein the anionic group-containing group has a partial structure represented by the following formula (1): (In formula (1), R ¹ and R ² are each independently a hydrogen atom, a halogen atom, a monovalent alkyl group having 1 to 20 carbon atoms, or a monovalent alkyl halide group having 1 to 20 carbon atoms; n is an integer from 1 to 10; when n is 2 or greater, multiple R ^1s are the same or different from each other, and multiple R ^2s are the same or different from each other; * represents a bonding site with a portion other than the structure represented by formula (1) in the anionic group-containing group).   The radiation-sensitive resin composition according to claim 3, wherein in the formula (1), at least one of ^R1 and ^R2 is a halogen atom or a monovalent halogenated alkyl group having 1 to 20 carbon atoms. The radiation-sensitive resin composition according to claim 1, wherein the anion-containing group further has a (thio)acetal structure. The radiation-sensitive resin composition according to claim 5, wherein the aromatic ring structure is bonded to the (thio)acetal structure. The radiation-sensitive resin composition according to claim 5, wherein the (thio)acetal structure is a cyclic (thio)acetal structure. The radiation-sensitive resin composition according to claim 7, wherein the cyclic (thio)acetal structure is represented by the following formula (2): (In formula (2), ^X1 and ^X2 are each independently an oxygen atom or a sulfur atom; ^R3 is a (m+2)-valent alkyl group having 1 to 20 carbon atoms; m is 1 or 2; and ** each represents a bonding site with a portion of the anionic group-containing group other than the structure represented by formula (2)). The radiation-sensitive resin composition according to claim 1, wherein the anion-containing group further has an alicyclic structure. A method for forming an anti-etching pattern comprises: directly or indirectly applying a radiation-sensitive resin composition as described in any one of claims 1 to 9 to a substrate; exposing the anti-etching film formed by the applying step; and developing the exposed anti-etching film. A compound comprising a cationic portion and a radiation-sensitive onium cation portion, wherein the cationic portion comprises an aromatic ring structure in which at least one hydrogen atom is substituted with a fluorine atom or a fluorine-containing group, and an anionic group bonded to the aromatic ring structure; wherein, in the aromatic ring structure, the number of covalent bonds constituting the shortest atomic chain between a first atom bonded to the fluorine atom or the fluorine-containing group and a second atom bonded to the anionic group is 2 or less.