Radiation-sensitive resin composition, method of forming resist pattern, and polymer

Abstract

To provide a radiation-sensitive resin composition excellent in sensitivity, CDU performance and development defect suppression, a resist pattern forming method, and a polymer.SOLUTION: The radiation-sensitive resin composition contains a polymer having a first structural unit represented by formula (1) and a compound represented by formula (2).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a radiation-sensitive resin composition, a method for forming a resist pattern, and a polymer. [Background technology]

[0002] Radiation-sensitive resin compositions used in microfabrication by lithography generate acid in exposed areas when irradiated with radiation such as far ultraviolet rays such as ArF excimer laser light (wavelength 193 nm) or KrF excimer laser light (wavelength 248 nm), electromagnetic waves such as extreme ultraviolet (EUV) (wavelength 13.5 nm), or charged particle rays such as electron beams; this acid catalyzed a chemical reaction that creates a difference in the dissolution rate in a developer between exposed and unexposed areas, thereby forming a resist pattern on a substrate.

[0003] Radiation-sensitive resin compositions are required to have good sensitivity to exposure light such as extreme ultraviolet rays and electron beams, as well as excellent CDU (Critical Dimension Uniformity) performance and development defect suppression.

[0004] To meet these demands, the types and molecular structures of polymers, acid generators, and other components used in radiation-sensitive resin compositions have been investigated, and combinations of these components have also been studied in detail (see JP-A-2010-134279, JP-A-2014-224984, and JP-A-2016-047815). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-134279 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-224984 [Patent Document 3] Japanese Patent Application Publication No. 2016-047815 Summary of the Invention [Problem to be solved by the invention]

[0006] As resist patterns become finer, the level of performance required is becoming higher and higher, and there is a demand for radiation-sensitive resin compositions that satisfy these requirements.

[0007] The present invention has been made in light of the above-mentioned circumstances, and an object of the present invention is to provide a radiation-sensitive resin composition, a method for forming a resist pattern, and a polymer that are excellent in sensitivity, CDU performance, and suppression of development defects. [Means for solving the problem]

[0008] The invention made to solve the above-mentioned problems is a radiation-sensitive resin composition (hereinafter also referred to as "composition (I)") containing a polymer (hereinafter also referred to as "polymer [A1]") having a first structural unit represented by the following formula (1) and whose solubility in a developer changes under the action of an acid, and a compound (hereinafter also referred to as "compound [Z]") represented by the following formula (2): [ka] (In formula (1), R 1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2 is a group formed by removing two hydrogen atoms bonded to one carbon atom from a substituted or unsubstituted aliphatic hydrocarbon ring structure having 3 to 30 ring members. 1 is a group in which one hydrogen atom has been removed from a substituted or unsubstituted aromatic hydrocarbon ring structure having 6 to 30 ring members. [ka] (In formula (2), Z is an acid-dissociable group. L 1 is *-O-CO- or -O-CO-O-. * indicates the bonding site with Z. Y is an (n+1)-valent organic group having 1 to 30 carbon atoms and not containing a cyclic acetal structure. A -is a monovalent anionic group. n is an integer of 1 to 5. When n is 2 or more, two or more Z's may be the same or different, and two or more L's may be the same or different. 1 are the same or different. X + is a monovalent radiation-sensitive onium cation.

[0009] Another invention made to solve the above-mentioned problems is a radiation-sensitive resin composition (hereinafter also referred to as "composition (II)") containing a polymer (hereinafter also referred to as "polymer [A2]") having a first structural unit represented by the following formula (1) and a third structural unit represented by the following formula (3-2), and whose solubility in a developer changes under the action of an acid, and a radiation-sensitive acid generator (hereinafter also referred to as "acid generator [B]"). [ka] (In formula (1), R 1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2 is a group formed by removing two hydrogen atoms bonded to one carbon atom from a substituted or unsubstituted aliphatic hydrocarbon ring structure having 3 to 30 ring members. 1 is a group in which one hydrogen atom has been removed from a substituted or unsubstituted aromatic hydrocarbon ring structure having 6 to 30 ring members. [ka] (In formula (3-2), R 3 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2 is a single bond, -COO-, -O-, or -CONH-. 2 is a group obtained by removing (s+t+1) hydrogen atoms from an aromatic hydrocarbon ring structure having 6 to 30 ring members. s is an integer of 1 to 3. When s is 1, the hydroxy group is 2 Among the carbon atoms that make up L 2 When s is 2 or more, at least one hydroxy group is bonded to a carbon atom adjacent to the carbon atom bonded to Ar 2 Among the carbon atoms that make up L 2It bonds to the carbon atom adjacent to the carbon atom bonded to R. t is an integer from 0 to 8. When t is 1, R 4 is a halogen atom or a monovalent organic group having 1 to 10 carbon atoms. When t is 2 or more, multiple R 4 are the same or different and are a halogen atom or a monovalent organic group having 1 to 10 carbon atoms, or a plurality of R 4 Two or more of these are combined with each other to form an alicyclic structure having 4 to 20 ring members together with the carbon chain to which they are attached.)

[0010] Yet another invention made to solve the above-mentioned problems is a method for forming a resist pattern, comprising the steps of applying the above-mentioned radiation-sensitive resin composition (composition (I) or composition (II)) directly or indirectly to a substrate, exposing the resist film formed by the application to light, and developing the exposed resist film.

[0011] Yet another invention made to solve the above problems is the polymer [A2]. [Effects of the Invention]

[0012] The radiation-sensitive resin composition of the present invention is excellent in sensitivity, CDU performance, and suppression of development defects. According to the method for forming a resist pattern of the present invention, a resist pattern can be formed that has good sensitivity, excellent CDU performance, and suppresses the occurrence of development defects. The polymer of the present invention can be suitably used as a component of the radiation-sensitive resin composition. Therefore, these polymers can be suitably used in the processing of semiconductor devices, which are expected to become even more miniaturized in the future. DETAILED DESCRIPTION OF THE INVENTION

[0013] The radiation-sensitive resin composition, the method for forming a resist pattern, and the polymer of the present invention will be described in detail below.

[0014] <Radiation sensitive resin composition> The radiation-sensitive resin composition may be embodied as the following composition (I) and composition (II). Composition (I): Contains the polymer [A1] and the compound [Z]. Composition (II): Contains the polymer [A2] and the acid generator [B]. In this specification, the polymer [A1] and the polymer [A2] may be collectively referred to as the "polymer [A]."

[0015] As will be described in detail later, the polymer [A2] is included in the polymer [A1], and the acid generator [B] is a radiation-sensitive acid generator other than the compound [Z]. Thus, a radiation-sensitive resin composition containing the polymer [A2] and the compound [Z] is one embodiment of composition (I).

[0016] The radiation-sensitive resin composition will be described below in the order of composition (I) and composition (II).

[0017] <Composition (I)> Composition (I) contains the polymer [A1] and the compound [Z]. Composition (I) usually contains an organic solvent (hereinafter also referred to as "organic solvent [D]"). Composition (I) may contain, as a preferred component, a radiation-sensitive acid generator other than the compound [Z] (hereinafter also referred to as "acid generator [B]") and / or an acid diffusion controller other than the compound [Z] (hereinafter also referred to as "acid diffusion controller [C]"). Composition (I) may contain, as a preferred component, a polymer having a higher fluorine atom content than the polymer [A] (hereinafter also referred to as "polymer [F]"). Composition (I) may contain other optional components as long as they do not impair the effects of the present invention.

[0018] Composition (I) contains the polymer [A1] and the compound [Z], and therefore has excellent sensitivity, CDU performance, and development defect suppression. The reason why composition (I) exhibits the above-mentioned effects due to its configuration is not entirely clear, but it is presumed, for example, as follows. That is, the polymer [A1] and the compound [Z] each have the specific structures described below, which improve the solubility or insolubility of the exposed area in the developer. As a result, composition (I) is thought to have excellent sensitivity, CDU performance, and development defect suppression.

[0019] Composition (I) can be prepared, for example, by mixing the polymer [A1] and the compound [Z], and, if necessary, the acid generator [B], the acid diffusion controller [C], the organic solvent [D] and other optional components, etc., in a predetermined ratio, and filtering the resulting mixture preferably through a membrane filter having a pore size of 0.2 μm or less.

[0020] Each component contained in the composition (I) will be described below.

[0021] <[A1] Polymer> The polymer [A1] has a first structural unit (hereinafter also referred to as "structural unit (I)") represented by the formula (1) described below, and is a polymer whose solubility in a developer changes under the action of an acid. The polymer [A1] exhibits the property of changing its solubility in a developer under the action of an acid due to the presence of the structural unit (I). The composition (I) can contain one or more types of polymer [A].

[0022] The polymer [A1] preferably further comprises a structural unit containing a phenolic hydroxyl group (hereinafter also referred to as "structural unit (II)"). The polymer [A1] may further comprise structural units other than the structural units (I) and (II) (hereinafter also simply referred to as "other structural units"). The polymer [A1] may comprise one or more types of each structural unit.

[0023] The structural units contained in the polymer [A1] may be considered to overlap with the classification of two or more structural units (for example, a structural unit classified as structural unit (II) may be considered to be classified as not only structural unit (II) but also structural units other than structural unit (II)). In this specification, such structural units are treated as corresponding to the structural unit with the lower number in parentheses.

[0024] The lower limit of the content of the polymer [A1] in the composition (I) is preferably 50 mass %, more preferably 70 mass %, and even more preferably 80 mass %, based on all components other than the organic solvent [D] contained in the composition (I).The upper limit of the content is preferably 99 mass %, more preferably 95 mass %.

[0025] The lower limit of the weight-average molecular weight (Mw) of the polymer [A1], as measured by gel permeation chromatography (GPC) in terms of polystyrene, is preferably 1,000, more preferably 3,000, even more preferably 4,000, even more preferably 5,000, and particularly preferably 6,000. 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 the polymer [A1] within the above range, the coatability of the composition (I) can be improved. The Mw of the polymer [A1] can be adjusted, for example, by adjusting the type and amount of polymerization initiator used in the synthesis.

[0026] The upper limit of the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the polymer [A1] measured by GPC (hereinafter also referred to as "Mw / Mn" or "polydispersity") is preferably 2.5, more preferably 2.0, and even more preferably 1.8. The lower limit of this ratio is usually 1.0, preferably 1.1, more preferably 1.2, and even more preferably 1.3.

[0027] [Method for measuring Mw and Mn] The Mw and Mn of the polymer in this specification are values ​​measured using gel permeation chromatography (GPC) under the following conditions. GPC columns: Two "G2000HXL" columns, one "G3000HXL" column, and one "G4000HXL" column from Tosoh Corporation Column temperature: 40℃ Elution solvent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0028] The polymer [A1] can be synthesized, for example, by polymerizing monomers that provide the respective structural units by a known method.

[0029] Each structural unit contained in the polymer [A1] will be described below.

[0030] Structural Units The structural unit (I) is a structural unit represented by the following formula (1).

[0031] [ka]

[0032] In the above formula (1), R 1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2 is a group formed by removing two hydrogen atoms bonded to one carbon atom from a substituted or unsubstituted aliphatic hydrocarbon ring structure having 3 to 30 ring members. 1 is a group in which one hydrogen atom has been removed from a substituted or unsubstituted aromatic hydrocarbon ring structure having 6 to 30 ring members.

[0033] The polymer [A1] can have one or more types of structural units (I).

[0034] The structural unit (I) is a structural unit containing an acid-dissociable group. The "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group, a hydroxy group, or the like, and dissociates under the action of an acid to give a carboxy group, a hydroxy group, or the like. In the above formula (1), the group bonded to the etheric oxygen atom of the carbonyloxy group (a group represented by the following formula (a)) is an acid-dissociable group (hereinafter also referred to as "acid-dissociable group (a)").

[0035] [ka]

[0036] In the above formula (a), R 2 and Ar 1 has the same meaning as in the above formula (1). * indicates the bonding site with the etheric oxygen atom of the carbonyloxy group in the above formula (1).

[0037] By using composition (I), the acid-dissociable group (a) dissociates from structural unit (I) due to the action of acid generated from compound [Z] upon exposure, resulting in a difference in the solubility of the polymer [A1] in a developer between the exposed and unexposed areas, allowing the formation of a resist pattern. The inclusion of the acid-dissociable group (a) in structural unit (I) of polymer [A1] is thought to be one of the reasons why composition (I) exhibits excellent sensitivity.

[0038] "Number of ring members" refers to the number of atoms constituting the ring structure, and in the case of a polycycle, it refers to the number of atoms constituting the polycycle. "Polycycle" includes not only spiro-type polycycles in which two rings share one shared atom and fused polycycles in which two rings share two shared atoms, but also ring assembly-type polycycles in which two rings do not share an atom and are connected by a single bond. "Ring structure" includes "alicyclic structure" and "aromatic ring structure." "Alicyclic structure" includes "aliphatic hydrocarbon ring structure" and "aliphatic heterocyclic structure." "Aromatic ring structure" includes "aromatic hydrocarbon ring structure" and "aromatic heterocyclic structure." "A group obtained by removing X hydrogen atoms from a ring structure" means a group obtained by removing X hydrogen atoms bonded to atoms constituting the ring structure.

[0039] R 1 From the viewpoint of copolymerizability of the monomer that gives the structural unit (I), a hydrogen atom or a methyl group is preferred, and a hydrogen atom is more preferred.

[0040] R 2Examples of the aliphatic hydrocarbon ring structure having 3 to 30 ring members that gives the formula include monocyclic saturated alicyclic structures such as a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, and a cyclohexane structure; polycyclic saturated alicyclic structures such as a norbornane structure and an adamantane structure; monocyclic unsaturated alicyclic structures such as a cyclobutene structure, a cyclopentene structure, and a cyclohexene structure; and polycyclic unsaturated alicyclic structures such as a norbornene structure. Among these, a monocyclic saturated alicyclic structure is preferred, and a cyclohexane structure is more preferred.

[0041] Some or all of the hydrogen atoms bonded to the carbon atoms constituting the aliphatic hydrocarbon ring structure may be substituted with a substituent, such as a halogen atom such as a fluorine atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, or an oxo group (═O).

[0042] The aliphatic hydrocarbon ring structure is preferably an unsubstituted aliphatic hydrocarbon ring structure.

[0043] R 2 is a group obtained by removing two hydrogen atoms bonded to one carbon atom from the above aliphatic hydrocarbon ring structure. 2 is a divalent group having two bonds on one carbon atom constituting an aliphatic hydrocarbon ring structure. In the above formula (1), the ether oxygen atom of the carbonyloxy group and Ar 1 is R 2 With this structure, the acid-dissociable group (a) is dissociated from the structural unit (I) by the action of acid generated by exposure, generating a carboxyl group.

[0044] Ar 1Examples of aromatic hydrocarbon ring structures having 6 to 30 ring members that give the formula include a benzene structure, condensed polycyclic aromatic hydrocarbon ring structures such as a naphthalene structure, an anthracene structure, a fluorene structure, a biphenylene structure, a phenanthrene structure, and a pyrene structure, and ring-assembled aromatic hydrocarbon ring structures such as a biphenyl structure, a terphenyl structure, a binaphthalene structure, and a phenylnaphthalene structure. Among these, a benzene structure is preferred.

[0045] Some or all of the hydrogen atoms bonded to the carbon atoms constituting the aromatic hydrocarbon ring structure may be substituted with a substituent, for example, the same as those exemplified as the substituents that the aliphatic hydrocarbon ring structure may have.

[0046] The acid-dissociable group (a) is preferably a 1-phenylcyclohexan-1-yl group.

[0047] The lower limit of the content of the structural unit (I) in the polymer [A1] is preferably 1 mol%, more preferably 5 mol%, and even more preferably 10 mol%, based on the total structural units constituting the polymer [A1]. The upper limit of the content is preferably 60 mol%, more preferably 50 mol%, and even more preferably 40 mol%. By setting the content of the structural unit (I) within the above range, the sensitivity, CDU performance, and development defect suppression properties of the composition (I) can be further improved. Unless otherwise specified, the upper and lower limits of numerical ranges described herein may be "equal to or less than" or "less than," and the lower limit may be "equal to or greater than" or "greater than." Furthermore, the upper and lower limits can be combined in any combination.

[0048] [Structural unit (II)] The structural unit (II) is a structural unit containing a phenolic hydroxyl group. The "phenolic hydroxyl group" refers not only to a hydroxyl group directly bonded to a benzene ring, but also to any hydroxyl group directly bonded to an aromatic ring. The polymer [A1] may contain one or more types of structural unit (II).

[0049] In the case of KrF exposure, EUV exposure, or electron beam exposure, the polymer [A1] having the structural unit (II) can further enhance the sensitivity of the composition (I). Therefore, when the polymer [A1] has the structural unit (II), the composition (I) can be suitably used as a radiation-sensitive resin composition for KrF exposure, EUV exposure, or electron beam exposure.

[0050] Examples of the structural unit (II) include a structural unit represented by the following formula (3-1) (hereinafter referred to as structural unit (II-1)).

[0051] [ka]

[0052] In the above formula (3-1), R 3 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2 is a single bond, -COO-, -O-, or -CONH-. 2 is a group obtained by removing (s+t+1) hydrogen atoms from an aromatic hydrocarbon ring structure having 6 to 30 ring members. s is an integer of 1 to 3. t is an integer of 0 to 8. When t is 1, R 4 is a halogen atom or a monovalent organic group having 1 to 20 carbon atoms. When t is 2 or more, multiple R 4 are the same or different and are a halogen atom or a monovalent organic group having 1 to 20 carbon atoms, or a plurality of R 4 Two or more of these are combined with each other to form an alicyclic structure having 4 to 20 ring members together with the carbon chain to which they are bonded.

[0053] "Carbon number" refers to the number of carbon atoms that make up a group. "Organic group" refers to a group that contains at least one carbon atom. "Valence" of a group refers to the number of atoms to which the group is bonded.

[0054] R 3 As the alkyl group, a hydrogen atom or a methyl group is preferred from the viewpoint of copolymerizability of the monomer that gives the structural unit (II-1).

[0055] L 2 is preferably a single bond or —COO—.

[0056] Ar 2 Examples of aromatic hydrocarbon ring structures having 6 to 30 ring members that give the formula (1) include Ar 1 Examples of the aromatic hydrocarbon ring structure having 6 to 30 ring members that gives the following formula are as follows: Among these, a benzene structure is preferred.

[0057] s is preferably 1 or 2, and more preferably 1.

[0058] R 4 The halogen atom in the formula (I) is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.

[0059] R 4 Examples of the monovalent organic group having 1 to 20 carbon atoms in the formula (I) include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group (α) containing a divalent heteroatom-containing group between the carbon-carbon bond of this hydrocarbon group, a group (β) in which some or all of the hydrogen atoms in the hydrocarbon group or the group (α) have been substituted with a monovalent heteroatom-containing group, and a group (γ) in which the hydrocarbon group, the group (α) or the group (β) is combined with a divalent heteroatom-containing group.

[0060] The term "hydrocarbon group" includes "aliphatic hydrocarbon groups" and "aromatic hydrocarbon groups." The term "aliphatic hydrocarbon group" includes "saturated hydrocarbon groups" and "unsaturated hydrocarbon groups." From another perspective, the term "aliphatic hydrocarbon group" includes "chain hydrocarbon groups" and "alicyclic hydrocarbon groups." A "chain hydrocarbon group" refers to a hydrocarbon group that does not contain a cyclic structure and is composed only of a chain structure, and includes both straight-chain hydrocarbon groups and branched hydrocarbon groups. An "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure as a ring structure and does not contain an aromatic ring structure, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups. However, it does not have to be composed solely of an alicyclic structure, and may contain a chain structure as part of it. An "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, it does not have to be composed solely of an aromatic ring structure, and may contain a chain structure or an alicyclic structure as part of it.

[0061] Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0062] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, isobutyl, and tert-butyl; alkenyl groups such as ethenyl, propenyl, butenyl, and 2-methylprop-1-en-1-yl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

[0063] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic alicyclic saturated hydrocarbon groups such as a cyclopentyl group and a cyclohexyl group; polycyclic alicyclic saturated hydrocarbon groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group; monocyclic alicyclic unsaturated hydrocarbon groups such as a cyclopentenyl group and a cyclohexenyl group; and polycyclic alicyclic unsaturated hydrocarbon groups such as a norbornenyl group, a tricyclodecenyl group, and a tetracyclododecenyl group.

[0064] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl; and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl.

[0065] Examples of heteroatoms constituting the monovalent or divalent heteroatom-containing group include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, and halogen atoms.

[0066] Examples of the monovalent heteroatom-containing group include a halogen atom, a hydroxy group, a carboxy group, a cyano group, an amino group, a sulfanyl group (-SH), and an oxo group (=O).

[0067] Examples of divalent heteroatom-containing groups include -O-, -CO-, -S-, -CS-, -NR'-, and groups combining two or more of these (for example, -COO-, -CONR'-, etc.). R' is 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 those having 1 to 10 carbon atoms among the groups exemplified above as "monovalent hydrocarbon groups having 1 to 20 carbon atoms".

[0068] Multiple R 4 Examples of the 4-20-membered alicyclic structure formed by combining two or more of the above together with the carbon chains to which they are bonded include monocyclic saturated alicyclic structures such as a cyclobutane structure, cyclopentane structure, and cyclohexane structure; polycyclic saturated alicyclic structures such as a norbornane structure, adamantane structure, tricyclodecane structure, and tetracyclododecane structure; monocyclic unsaturated alicyclic structures such as a cyclopropene structure, cyclobutene structure, cyclopentene structure, and cyclohexene structure; and polycyclic unsaturated alicyclic structures such as a norbornene structure, tricyclodecene structure, and tetracyclododecene structure.

[0069] t is preferably 0 or 1, and 0 is more preferable.

[0070] Examples of the structural unit (II-1) include structural units represented by the following formulas (3-1-1) to (3-1-18) (hereinafter also referred to as "structural units (II-1-1) to (II-1-18)"). Among these, the structural unit (3-1-1), the structural unit (3-1-3), the structural unit (3-1-8), the structural unit (3-1-9), the structural unit (3-1-12), or a combination thereof is preferred.

[0071] [ka]

[0072] In the above formulas (3-1-1) to (3-1-18), R 3 is synonymous with the above formula (3-1).

[0073] When the polymer [A1] has the structural unit (II-1), the lower limit of the content of the structural unit (II-1) in the polymer [A1] is preferably 20 mol %, more preferably 30 mol %, and even more preferably 40 mol %, based on the total structural units constituting the polymer [A1].The upper limit of the content is preferably 70 mol %, more preferably 60 mol %, and even more preferably 50 mol %.

[0074] Examples of monomers that provide the structural unit (II) include monomers in which the hydrogen atom of a phenolic hydroxyl group (-OH) is substituted with an acetyl group, such as 4-acetoxystyrene and 3,5-diacetoxystyrene. In this case, for example, the above-mentioned monomers can be polymerized, and then the resulting polymerization product can be hydrolyzed in the presence of a base such as an amine, thereby synthesizing the polymer [A1] having the structural unit (II).

[0075] From another viewpoint, among the structural units (II-1), the structural unit represented by the formula (3-2) described later (hereinafter also referred to as "structural unit (IIa)") is preferred, as this can further improve the suppression of development defects.

[0076] (Structural unit (IIa)) The structural unit (IIa) is a type of structural unit (structural unit (II)) containing a phenolic hydroxyl group, and is a structural unit represented by the following formula (3-2). The following formula (3-2) is a type of the above formula (3-1), and specifies the bonding position of the hydroxy group. Among the polymers [A1], a polymer further having the structural unit (IIa) is the polymer [A2].

[0077] [ka]

[0078] In the above formula (3-2), R 3 , L 2 , R 4 , Ar 2 , s and t have the same meanings as in the above formula (3-1). However, when s is 1, the hydroxy group is Ar 2 Among the carbon atoms that make up L 2 When s is 2 or more, at least one hydroxy group is bonded to a carbon atom adjacent to the carbon atom bonded to Ar 2 Among the carbon atoms that make up L 2 It bonds to the carbon atom adjacent to the carbon atom bonded to it.

[0079] The structural unit (IIa) is a structural unit represented by the above formula (3-1) in which at least one hydroxy group is Ar 2 Among the carbon atoms that make up L 2 In other words, at least one hydroxy group and L 2 Ar 2 are bonded to each other in the ortho position.

[0080] The polymer [A1] can further improve the development defect suppression property by containing the structural unit (IIa). The reason for this effect is not entirely clear, but it is presumed, for example, as follows. As described above, the polymer [A] and the compound [Z] each have a specific structure, which improves the solubility or insolubility in the developer in the exposed area. Furthermore, the polymer [A] has the structural unit (IIa), which makes it possible to appropriately adjust the interaction between the polymer [A] and the compound [Z], etc., and further improves the solubility or insolubility in the developer in the exposed area. As a result, it is believed that the composition (I) exhibits better development defect suppression property.

[0081] The structural unit (IIa) is preferably a structural unit represented by the above formula (3-1-3) (structural unit (II-1-3)), a structural unit represented by the above formula (3-1-8) (structural unit (II-1-8)), a structural unit represented by the above formula (3-1-12) (structural unit (II-1-12)), or a combination thereof, and more preferably a structural unit (II-1-3), a structural unit (II-1-12), or a combination thereof. In this case, development defect suppression can be further improved.

[0082] When the polymer [A1] has the structural unit (IIa), the lower limit of the content of the structural unit (IIa) in the polymer [A1] is preferably 10 mol %, more preferably 20 mol %, and even more preferably 30 mol %, based on the total structural units constituting the polymer [A1].The upper limit of the content is preferably 70 mol %, more preferably 60 mol %, and even more preferably 50 mol %.

[0083] When the polymer [A1] has the structural unit (IIa), the polymer [A1] may contain a structural unit (II) other than the structural unit (IIa) (hereinafter also referred to as "structural unit (IIb)"). In this case, the content of the structural unit (IIb) in the polymer [A1] can be appropriately adjusted based on the content of the structural unit (IIa) described above, within the range of the content of the structural unit (II) described above.

[0084] Other structural units Examples of other structural units include a structural unit containing an acid-dissociable group other than the acid-dissociable group (a) (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 a structural unit containing an alcoholic hydroxyl group (hereinafter also referred to as "structural unit (V)").

[0085] (Structural unit (III)) The structural unit (III) is a structural unit containing an acid dissociable group other than the acid dissociable group (a) (hereinafter also referred to as "acid dissociable group (b)"). The structural unit (III) is a structural unit different from the structural unit (I).

[0086] Examples of the structural unit (III) include structural units represented by the following formulae (III-1) to (III-3) (hereinafter also referred to as "structural units (III-1) to (III-3)"). For example, in the following formula (III-1), -C(R X )(R Y )(R Z ) corresponds to the acid-dissociable group (b).

[0087] [ka]

[0088] In the above formulas (III-1) to (III-3), R T are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0089] In the above formula (III-1), R X R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. Y and R Z are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or these groups are combined with each other to form a saturated alicyclic structure having 3 to 20 ring members together with the carbon atoms to which they are bonded.Y and R Z When R X is a substituted or unsubstituted monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms.

[0090] In the above formula (III-2), R A is a hydrogen atom. B and R C are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. D is R A , R B and R C are divalent hydrocarbon groups having 1 to 20 carbon atoms which, together with the carbon atoms to which they are bonded, form an unsaturated alicyclic structure having 4 to 20 ring members.

[0091] In the above formula (III-3), R U and R V are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R W is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R U and R V are combined with each other to form an alicyclic structure having 3 to 20 ring members together with the carbon atoms to which they are bonded, or R U and R W are aligned with each other and R U and the carbon atom to which R is bonded W together with the oxygen atom to which it is bonded, form an aliphatic heterocyclic structure having 4 to 20 ring members.

[0092] R T From the viewpoint of copolymerizability of the monomer that gives the structural unit (III), a hydrogen atom or a methyl group is preferred.

[0093] R X , R Y , R Z , R B , R C , R U , R V or R W Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (3-1) include R4 Among the monovalent organic groups having 1 to 20 carbon atoms represented by the following formula, the same groups as those exemplified as the monovalent hydrocarbon groups having 1 to 20 carbon atoms can be mentioned.

[0094] Above R X Examples of the substituents that may be possessed by the hydrocarbon group represented by the formula (1) include R 2 Examples of the substituent that the aliphatic hydrocarbon ring structure that gives the following formula may have include the same as those exemplified above.

[0095] R Y and R Z are combined with each other to form a saturated alicyclic structure having 3 to 20 ring members together with the carbon atoms to which they are bonded, and R U and R V Examples of the alicyclic structure having 3 to 20 ring members formed by combining these together with the carbon atoms to which they are bonded include monocyclic saturated alicyclic structures such as a cyclopropane structure, cyclobutane structure, cyclopentane structure, and cyclohexane structure; polycyclic saturated alicyclic structures such as a norbornane structure, adamantane structure, tricyclodecane structure, and tetracyclododecane structure; monocyclic unsaturated alicyclic structures such as a cyclopropene structure, cyclobutene structure, cyclopentene structure, and cyclohexene structure; and polycyclic unsaturated alicyclic structures such as a norbornene structure, tricyclodecene structure, and tetracyclododecene structure.

[0096] R D Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include the above-mentioned R X , R Y , R Z , R B , R C , R U , R V or R W Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include groups in which one hydrogen atom has been removed from the groups exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the following formula:

[0097] R D R A , R B and R CExamples of the unsaturated alicyclic structure having 4 to 20 ring members that is formed together with the carbon atoms to which each is bonded include monocyclic unsaturated alicyclic structures such as a cyclobutene structure, a cyclopentene structure, and a cyclohexene structure, and polycyclic unsaturated alicyclic structures such as a norbornene structure.

[0098] R U and R W are aligned with each other and R U and the carbon atom to which R is bonded W Examples of the 4-20-membered aliphatic heterocyclic structure formed together with the oxygen atom to which is bonded include saturated oxygen-containing heterocyclic structures such as an oxacyclobutane structure, an oxacyclopentane structure, and an oxacyclohexane structure; and unsaturated oxygen-containing heterocyclic structures such as an oxacyclobutene structure, an oxacyclopentene structure, and an oxacyclohexene structure.

[0099] R Y and R Z is a monovalent hydrocarbon group having 1 to 20 carbon atoms, R Y and R Z As R, a chain hydrocarbon group is preferable, an alkyl group is preferable, and a methyl group is more preferable. X As the alkyl group, a substituted or unsubstituted aromatic hydrocarbon group is preferable, an unsubstituted aryl group is more preferable, and a phenyl group is even more preferable.

[0100] R Y and R Z When these are combined with each other to form a saturated alicyclic structure having 3 to 20 ring members together with the carbon atoms to which they are bonded, the saturated alicyclic structure is preferably a monocyclic saturated alicyclic structure or a polycyclic saturated alicyclic structure, and more preferably a cyclopentane structure, an adamantane structure, or a tetracyclododecane structure. X As the alkyl group, a substituted or unsubstituted chain hydrocarbon group is preferable, an unsubstituted alkyl group is more preferable, and a methyl group or an ethyl group is even more preferable.

[0101] The structural unit (III) is preferably the structural unit (III-1).

[0102] As the structural unit (III-1), structural units represented by the following formulae (III-1-1) to (III-1-4) are preferred.

[0103] [ka]

[0104] In the above formulas (III-1-1) to (III-1-4), R T has the same meaning as the above formula (III-1).

[0105] When the polymer [A1] contains the structural unit (III), the lower limit of the content of the structural unit (III) is preferably 10 mol %, more preferably 20 mol %, based on the total structural units constituting the polymer [A1].The upper limit of the content is preferably 50 mol %, more preferably 40 mol %.

[0106] (Structural unit (IV)) The structural unit (IV) is a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof.

[0107] Examples of the structural unit (IV) include structural units represented by the following formula:

[0108] [ka]

[0109] [ka]

[0110] [ka]

[0111] [ka]

[0112] In the above formula, R L1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0113] The structural unit (IV) is preferably a structural unit containing a lactone structure, a sultone structure, or a combination thereof.

[0114] When the polymer [A1] has the structural unit (IV), the lower limit of the content of the structural unit (IV) is preferably 5 mol %, more preferably 10 mol %, based on the total structural units constituting the polymer [A1], and the upper limit of the content is preferably 30 mol %, more preferably 20 mol %.

[0115] (Structural unit (V)) The structural unit (V) is a structural unit containing an alcoholic hydroxyl group. By further including the structural unit (V), the solubility in the developer can be adjusted more appropriately. The polymer [A1] can contain one or more types of structural units (V).

[0116] Examples of the structural unit (V) include structural units represented by the following formulas.

[0117] [ka]

[0118] In the above formula, R L2 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0119] When the polymer [A1] has the structural unit (V), the lower limit of the content of the structural unit (V) is preferably 5 mol %, more preferably 15 mol %, based on the total structural units in the polymer [A1], and the upper limit of the content is preferably 30 mol %, more preferably 20 mol %.

[0120] <[Z] compound> The [Z] compound is a compound represented by the following formula (2): The composition (I) can contain one or more [Z] compounds.

[0121] [ka]

[0122] In the above formula (2), Z is an acid-dissociable group. 1 is -O-CO- or -O-. * indicates the bonding site with Z. Y is a (n+1)-valent organic group having 1 to 30 carbon atoms and not containing a cyclic acetal structure. n is an integer of 1 to 5. When n is 2 or more, two or more Zs may be the same or different, and two or more Ls may be the same or different. 1 are the same or different. A - is a monovalent anionic group. X + is a monovalent radiation-sensitive onium cation.

[0123] Hereinafter, (ZL 1 ) n -YA - The structure represented by X is also called the "anion part." + The structure represented by the formula (2) is also called the "cation moiety." In addition, Z in the formula (2) is also called the "acid-dissociable group (z)," Y is also called the "skeletal structure (Y)," and A - is also called an "anionic group."

[0124] Depending on the type of anionic group, the compound [Z] has the function of generating an acid in composition (I) upon irradiation with radiation, or the function of controlling the diffusion phenomenon in the resist film of an acid generated by the acid generator [B] or the like upon exposure, thereby suppressing undesirable chemical reactions in unexposed areas (for example, dissociation reactions of acid-dissociable groups). In other words, depending on the type of anionic group, the compound [Z] functions as a radiation-sensitive acid generator or an acid diffusion controller (quencher) in composition (I).

[0125] When the compound [Z] functions as a radiation-sensitive acid generator, examples of the radiation include the same as those exemplified as the exposure light in the exposure step of the method for forming a resist pattern described below. The acid generated from the compound [Z] upon irradiation with radiation dissociates the acid-dissociable group (a) contained in the structural unit (I) of the polymer [A1] to generate a carboxyl group, etc., which results in a difference in the solubility of the resist film in a developer between the exposed and unexposed areas, thereby forming a resist pattern.

[0126] When the compound [Z] functions as an acid diffusion controller, it generates acid in the exposed area to increase the solubility or insolubility of the polymer [A1] in a developer, while in the unexposed area, it exerts a high acid-scavenging function due to the anion, functions as a quencher, and captures acid diffusing from the exposed area, thereby improving the roughness at the interface between the exposed and unexposed areas and the contrast between the exposed and unexposed areas, thereby improving resolution.

[0127] Regardless of the function of the [Z] compound in composition (I) described above, the inclusion of the [Z] compound in composition (I) is considered to be one of the factors that enable composition (I) to exhibit excellent development defect suppression properties.

[0128] When the compound [Z] functions as a radiation-sensitive acid generator, the lower limit of the content of the compound [Z] in the composition (I) is preferably 1 part by mass, more preferably 2 parts by mass, relative to 100 parts by mass of the polymer [A1], and the upper limit of the content is preferably 10 parts by mass, more preferably 5 parts by mass.

[0129] When the compound [Z] functions as an acid diffusion controller, the lower limit of the content of the compound [Z] in the composition (I) is preferably 1 part by mass, more preferably 2 parts by mass, per 100 parts by mass of the polymer [A1], and the upper limit of the content is preferably 10 parts by mass, more preferably 5 parts by mass.

[0130] Each structure of the [Z] compound will be explained below.

[0131] [Anion part] The anion portion is (ZL 1 ) n -YA - It is a structure represented by the following formula: n is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1.

[0132] (L 1 ) L 1 are groups bonded to the acid-dissociable group (a) and the skeletal structure (Y), respectively. 1 When L is -O-CO-, a carboxyl group is generated when the acid-dissociable group (z) dissociates. 1 When is -O-, a hydroxy group is generated upon dissociation of the acid-dissociable group (z).

[0133] (Acid dissociable group (z)) The acid-labile group (z) is L 1 The acid-dissociable group (z) is a group that substitutes a hydrogen atom in a carboxy group or a hydroxy group, and dissociates by the action of an acid to give a carboxy group or a hydroxy group. The presence of the acid-dissociable group (z) in the [Z] compound is thought to be one of the factors that enable composition (I) to exhibit excellent development defect suppression properties.

[0134] Examples of the acid-dissociable group (z) include groups represented by the following formulae (z-1) to (z-3) (hereinafter also referred to as "acid-dissociable groups (z-1) to (z-3)").

[0135] [ka]

[0136] In the above formulas (z-1) to (z-3), * represents L in the above formula (2). 1 The binding site is shown.

[0137] In the above formula (z-1), R Z1 is a monovalent hydrocarbon group having 1 to 20 carbon atoms.Z2 and R Z3 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or these groups are combined with each other to form a saturated alicyclic structure having 3 to 20 ring members together with the carbon atoms to which they are bonded.

[0138] In the above formula (z-2), R Z4 is a hydrogen atom. Z5 and R Z6 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. Z7 is R Z4 , R Z5 and R Z6 are divalent hydrocarbon groups having 1 to 20 carbon atoms which, together with the carbon atoms to which they are bonded, form an unsaturated alicyclic structure having 4 to 20 ring members.

[0139] In the above formula (z-3), R Z8 and R Z9 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R Z10 is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R Z8 and R Z9 are combined with each other to form an alicyclic structure having 3 to 20 ring members together with the carbon atoms to which they are bonded, or R Z8 and R Z10 are aligned with each other and R Z8 and the carbon atom to which R is bonded Z10 together with the oxygen atom to which it is bonded, form an aliphatic heterocyclic structure having 4 to 20 ring members.

[0140] R Z1 , R Z2 , R Z3 , R Z5 , R Z6 , R Z8 , R Z9 or R Z10 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (3-1) include R 4 Among the monovalent organic groups having 1 to 20 carbon atoms represented by the following formula, the same groups as those exemplified as the monovalent hydrocarbon groups having 1 to 20 carbon atoms can be mentioned.

[0141] R Z2 and R Z3 are combined with each other to form a saturated alicyclic structure having 3 to 20 ring members together with the carbon atoms to which they are bonded, and R Z8 and R Z9 Examples of the alicyclic structure having 3 to 20 ring members formed by combining these together with the carbon atoms to which they are bonded include R Y and R Z are combined with each other to form a saturated alicyclic structure having 3 to 20 ring members together with the carbon atoms to which they are bonded, and R U and R V and the like, which are the same as those exemplified as examples of the alicyclic structure having 3 to 20 ring members formed by combining these together with the carbon atoms to which they are bonded.

[0142] R Z7 Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (3-1) include R 4 Among the monovalent organic groups having 1 to 20 carbon atoms represented by the following formula, groups in which one hydrogen atom has been removed from the groups exemplified as the monovalent hydrocarbon groups having 1 to 20 carbon atoms are exemplified.

[0143] R Z7 R Z4 , R Z5 and R Z6 Examples of the unsaturated alicyclic structure having 4 to 20 ring members formed together with the carbon atoms to which each of R is bonded include R in the above formula (III-2): D R A , R B and R C and the like, which are the same as the examples of the unsaturated alicyclic structure having 4 to 20 ring members that is formed together with the carbon atoms to which they are bonded.

[0144] R Z8 and R Z10 are aligned with each other and R Z8 and the carbon atom to which R is bonded Z10 Examples of the aliphatic heterocyclic structure having 4 to 20 ring members that is formed together with the oxygen atom to which R is bonded include R in the above formula (III-3). U and RW are aligned with each other and R U and the carbon atom to which R is bonded W Examples of the heterocyclic structure include the same as those exemplified as the aliphatic heterocyclic structure having 4 to 20 ring members that is formed together with the oxygen atom to which it is bonded.

[0145] Some or all of the hydrogen atoms bonded to the atoms constituting the hydrocarbon group or ring structure may be substituted with a substituent. Examples of the substituent include a monovalent heteroatom-containing group and a monovalent organic group having 1 to 20 carbon atoms. The monovalent heteroatom-containing group and the monovalent organic group having 1 to 20 carbon atoms are represented by R in the above formula (3-1). 4 This is explained in.

[0146] Preferred examples of the substituent include a halogen atom, a hydroxy group, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group (α) containing a divalent heteroatom-containing group between the carbon-carbon bonds of this hydrocarbon group, a group (β) in which some or all of the hydrogen atoms in the hydrocarbon group or the group (α) have been substituted with a monovalent heteroatom-containing group, and a group (γ) in which the hydrocarbon group, the group (α) or the group (β) is combined with a divalent heteroatom-containing group.

[0147] Furthermore, a monovalent group containing an acid-dissociable group (z) is also preferred as the substituent. Examples of such a substituent include *-L A1 -L 1 -Z (L A1 is a divalent linking group described later. 1 and Z have the same meaning as in the above formula (2). * indicates the bonding site with the acid-dissociable group (z).

[0148] R Z1 As the alkyl group, a chain hydrocarbon group is preferable, an alkyl group is more preferable, and a methyl group, an ethyl group, an i-propyl group or a tert-butyl group is even more preferable.

[0149] R Z2 and R Z3 is a monovalent hydrocarbon group having 1 to 20 carbon atoms, R Y and R Zis preferably a chain hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group, more preferably an alkyl group, a monocyclic alicyclic saturated hydrocarbon group, a polycyclic alicyclic saturated hydrocarbon group, or an aryl group, and still more preferably a methyl group, an ethyl group, an i-propyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, or a phenyl group.

[0150] R Z2 and R Z3 When these are combined with each other to form a saturated alicyclic structure having 3 to 20 ring members together with the carbon atoms to which they are bonded, the saturated alicyclic structure is preferably a monocyclic saturated alicyclic structure or a polycyclic saturated alicyclic structure, and more preferably a cyclopentane structure, cyclohexane structure, norbornane structure, adamantane structure, tricyclodecane structure, or tetracyclododecane structure.

[0151] R Z5 is preferably a hydrogen atom.

[0152] R Z6 is preferably a hydrogen atom or a chain hydrocarbon group, more preferably a hydrogen atom or an alkyl group, and even more preferably a hydrogen atom or a methyl group.

[0153] R Z7 R Z4 , R Z5 and R Z6 The unsaturated alicyclic structure having 4 to 20 ring members constituted by these groups together with the carbon atoms to which they are bonded is preferably a monocyclic unsaturated alicyclic structure, more preferably a cyclopentene structure or a cyclohexene structure.

[0154] R Z8 and R Z9 is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and R Z10 The case where R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms (pattern 1) will be described. Z8 and R Z9is preferably a hydrogen atom or a chain hydrocarbon group, more preferably a hydrogen atom or an alkyl group, and even more preferably a hydrogen atom, a methyl group, an ethyl group, or an i-propyl group. Z10 As the alkyl group, a chain hydrocarbon group or an alicyclic hydrocarbon group is preferable, an alkyl group or a polycyclic alicyclic saturated hydrocarbon group is more preferable, and a methyl group, an ethyl group, an adamantyl group or a tricyclododecyl group is even more preferable.

[0155] R Z8 and R Z10 are aligned with each other and R Z8 and the carbon atom to which R is bonded Z10 Hereinafter, a case where, together with the oxygen atom to which it is bonded, it forms a substituted or unsubstituted aliphatic heterocyclic structure having 4 to 20 ring members (Pattern 3) will be described. In this case, the aliphatic heterocyclic structure is preferably a saturated oxygen-containing heterocyclic structure, and more preferably an oxacyclohexane structure.

[0156] The acid-dissociable group (z) is preferably the acid-dissociable group (z-1) or (z-3).

[0157] Examples of the acid dissociable group (z-1) include groups represented by the following formulae (z-1-1) to (z-1-26) (hereinafter also referred to as "acid dissociable groups (z-1-1) to (z-1-26)").

[0158] [ka]

[0159] In the above formulas (z-1-1) to (z-1-26), * has the same meaning as in the above formula (z-1).

[0160] Examples of the acid dissociable group (z-3) include groups represented by the following formulae (z-3-1) to (z-3-11) (hereinafter also referred to as "acid dissociable groups (z-3-1) to (z-3-11)").

[0161] [ka]

[0162] In the above formulas (z-3-1) to (z-3-11), * has the same meaning as in the above formula (z-3).

[0163] (skeletal structure (Y)) The skeletal structure (Y) is an (n+1)-valent organic group having 1 to 30 carbon atoms that does not contain a cyclic acetal structure. The "cyclic acetal structure" includes not only monocyclic cyclic acetal structures but also polycyclic cyclic acetal structures. Polycyclic cyclic acetal structures include spiro-type polycyclic structures in which a monocyclic acetal structure such as dioxolane and an aliphatic hydrocarbon ring structure such as cyclohexane share one shared atom, and fused polycyclic structures in which the two rings share two shared atoms.

[0164] Examples of the (n+1)-valent organic group having 1 to 30 carbon atoms and not containing a cyclic acetal structure include a monovalent hydrocarbon group having 1 to 30 carbon atoms, a group (α) containing a divalent heteroatom-containing group between the carbon-carbon bond of this hydrocarbon group, a group (β) in which some or all of the hydrogen atoms in the hydrocarbon group or the group (α) have been substituted with a monovalent heteroatom-containing group, and a group (γ) in which the hydrocarbon group, the group (α) or the group (β) is combined with a divalent heteroatom-containing group. The divalent heteroatom-containing group and the monovalent heteroatom-containing group are represented by R in the above formula (3-1). 4 Examples of the monovalent organic group having 1 to 20 carbon atoms include the same groups as those exemplified in the description of the monovalent organic group having 1 to 20 carbon atoms.

[0165] The skeletal structure (Y) preferably contains only an aliphatic hydrocarbon ring structure, an aromatic hydrocarbon ring structure, an aromatic heterocyclic structure, or a combination thereof as a ring structure. In other words, the skeletal structure (Y) does not contain any ring structure other than an aliphatic hydrocarbon ring structure, an aromatic hydrocarbon ring structure, an aromatic heterocyclic structure, or a combination thereof. The "combination thereof" includes not only cases where two or more ring structures are directly bonded, but also cases where they are bonded via a divalent linking group described below.

[0166] The aliphatic hydrocarbon ring structure includes R2 Among these, a monocyclic saturated alicyclic structure, a polycyclic saturated alicyclic structure, or a polycyclic unsaturated alicyclic structure is preferred, and a cyclohexane structure, an adamantane structure, or a norbornene structure is more preferred.

[0167] Examples of the aromatic hydrocarbon ring structure include Ar in the above formula (1). 1 Examples of the aromatic hydrocarbon ring structure having 6 to 30 ring members that gives the following formula are listed below. Among these, a benzene structure or a naphthalene structure is preferred.

[0168] Examples of the aromatic heterocyclic structure include oxygen atom-containing heterocyclic structures such as a furan structure, a pyran structure, a benzofuran structure, and a benzopyran structure, nitrogen atom-containing heterocyclic structures such as a pyridine structure, a pyrimidine structure, and an indole structure, and sulfur atom-containing heterocyclic structures such as a thiophene structure and a dibenzothiophene structure. Among these, an oxygen atom-containing heterocyclic structure or a sulfur atom-containing heterocyclic structure is preferred, and a benzofuran structure or a dibenzothiophene structure is more preferred.

[0169] Some or all of the hydrogen atoms bonded to the atoms constituting the ring structure may be substituted with a substituent. Examples of the substituent include a monovalent heteroatom-containing group and a monovalent organic group having 1 to 20 carbon atoms. The monovalent heteroatom-containing group and the monovalent organic group having 1 to 20 carbon atoms are R in the above formula (3-1). 4 This is explained in.

[0170] The above-mentioned substituent is preferably a halogen atom, a hydroxy group, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group (α) containing a divalent heteroatom-containing group between the carbon-carbon bond of a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a group (γ) combining a monovalent hydrocarbon group having 1 to 20 carbon atoms with a divalent heteroatom-containing group, and more preferably a fluorine atom, an iodine atom, a hydroxy group, an alkyl group, an alkoxy group, an alkoxyalkyloxy group, or a group combining a monovalent hydrocarbon group having 1 to 20 carbon atoms with a carbonyloxy group or an oxycarbonyl group.

[0171] The skeletal structure (Y) preferably further comprises a divalent chain hydrocarbon group having 1 to 10 carbon atoms or a group in which some or all of the hydrogen atoms in this chain hydrocarbon group have been substituted with fluorine atoms (hereinafter also referred to as a "fluorinated chain hydrocarbon group"). In addition, the chain hydrocarbon group or fluorinated chain hydrocarbon group is preferably bonded to the anionic group.

[0172] In the basic skeleton (Y), the ring structure and the chain hydrocarbon group or fluorinated chain hydrocarbon group may be bonded directly or via a divalent linking group.

[0173] Examples of the divalent linking group include a carbonyl group, an ether group, a sulfide group, an alkanediyl group having 1 to 10 carbon atoms, and groups formed by combining these groups.

[0174] Examples of the basic skeleton (Y) include an (n+1)-valent group represented by the following formula (Y-1).

[0175] [ka]

[0176] In the above formula (Y-1), R A1 is a group obtained by removing (n+b+1) hydrogen atoms from a ring structure other than a cyclic acetal structure. a is 0 or 1. R A2 is a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, or a monovalent organic group having 1 to 10 carbon atoms. b is an integer of 0 to 5. When a is 0, b is also 0. When b is 2 or more, multiple R A2 are the same or different. A1 and L A2 is a single bond or a divalent linking group. n is the same as n in the above formula (2). R A3 and R A4are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. c is an integer of 1 to 10. When c is 2 or more, multiple R A3 are the same or different, and multiple R A4 are the same or different. *1 is L in the above formula (2). 1 *2 is the bonding site with A in the above formula (2). - This is the binding site for

[0177] R A1 Examples of the ring structure other than the cyclic acetal structure that gives the above formula include the above-mentioned aliphatic hydrocarbon ring structure, aromatic hydrocarbon ring structure, and aromatic heterocyclic structure, as well as an aliphatic heterocyclic structure other than the cyclic acetal, or a combination thereof. Among these, an adamantane structure or a benzene structure is particularly preferred.

[0178] When a is 0, the basic skeleton (Y) does not contain a ring structure and has a chain structure.

[0179] R A2 is preferably an iodine atom.

[0180] b is preferably 0 to 2.

[0181] L A1 and L A2 is preferably a single bond, an ether group or a carbonyloxy group.

[0182] c is preferably 1 to 3, and more preferably 1 or 2.

[0183] -(C(R A3 )(R A4 )) cThe group represented by - is preferably a difluoromethyldiyl group, an ethane-1,2-diyl group, a 1-fluoroethane-1,2-diyl group, a 1,1-difluoroethane-1,2-diyl group, a 1,1-difluoro-2,2-dimethylethane-1,2-diyl group, or a 1,1-difluoro-2-isopropylethane-1,2-diyl group.

[0184] (anionic group) The anionic group is a group bonded to the above-mentioned skeletal structure (Y). As the anionic group, a monovalent organic acid anionic group is preferred, and a sulfonate group (-SO3 - ) or carboxylate group (-COO - ) is more preferred.

[0185] As described above, the compound [Z] functions as a radiation-sensitive acid generator or an acid diffusion controller (quencher) in the composition (I) depending on the type of anionic group.

[0186] When the anion group is a sulfonate group, the compound [Z] functions as a radiation-sensitive acid generator in the composition (I). In this case, the composition (I) preferably contains an acid diffusion controller [C]. In this case, the composition (I) may also contain an acid generator (acid generator [B]) other than the compound [Z].

[0187] When the anion group is a carboxylate group, the [Z] compound functions as an acid diffusion controller in the composition (I). In this case, the composition (I) preferably contains the acid generator [B]. In this case, the composition (I) may also contain an acid diffusion controller (acid diffusion controller [C]) other than the [Z] compound.

[0188] When the anionic group is a sulfonate group, examples of the anionic moiety include partial structures represented by the following formulas (A-1-1) to (A-1-3) (hereinafter also referred to as "anionic moieties (A-1-1) to (A-1-3)").

[0189] [ka]

[0190] When the anionic group is a carboxylate group, examples of the anionic moiety include partial structures represented by the following formulas (A-2-1) to (A-2-4) (hereinafter also referred to as "anionic moieties (A-2-1) to (A-2-4)").

[0191] [ka]

[0192] [Cation part] X + Examples of the monovalent radiation-sensitive onium cation represented by the formula (ra) include monovalent cations represented by the following formulas (ra) to (rc) (hereinafter also referred to as "cations (ra) to (rc)").

[0193] [ka]

[0194] In the above formula (ra), R B1 and R B2 are each independently a group in which one hydrogen atom has been removed from a substituted or unsubstituted aromatic hydrocarbon ring structure having 6 to 20 ring members, or R B1 and R B2 Together with the sulfur atom to which they are bonded, they form a substituted or unsubstituted polycyclic aromatic ring structure having 9 to 30 ring members. B3 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. b1 is an integer of 0 to 9. When b1 is 2 or more, multiple R B3 are the same or different. n b1 is an integer from 0 to 3.

[0195] In the above formula (rb), R B4 and R B5are each independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. b2 is an integer of 0 to 9. When b2 is 2 or more, multiple R B4 are the same or different from each other. b3 is an integer of 0 to 10. When b3 is 2 or more, multiple R B5 are the same or different. R is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. B6 is a single bond or a divalent organic group having 1 to 20 carbon atoms. b2 is an integer from 0 to 2. b3 is an integer from 0 to 3.

[0196] In the above formula (rc), R B7 and R B8 are each independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. b4 is an integer of 0 to 5. When b4 is 2 or more, multiple R B7 are the same or different from each other. b5 is an integer of 0 to 5. When b5 is 2 or more, multiple R B8 are the same or different from each other.

[0197] R B1 and R B2 is a group in which one hydrogen atom has been removed from a substituted or unsubstituted aromatic hydrocarbon ring structure having 6 to 20 ring members, examples of the aromatic hydrocarbon ring structure include Ar 1 Among the examples of aromatic hydrocarbon ring structures having 6 to 30 ring members that give the following formula, those having 6 to 20 ring members can be mentioned. Of these, a benzene structure is preferred.

[0198] R B1 and R B2 When these are combined with each other to form a polycyclic aromatic ring structure having 9 to 30 ring members together with the sulfur atom to which they are bonded, examples of the polycyclic aromatic ring structure include a benzothiophene structure, a dibenzothiophene structure, a thioxanthene structure, a thioxanthone structure, and a phenoxathiin structure. Of these, a dibenzothiophene structure is preferred.

[0199] A part or all of the hydrogen atoms bonded to the atoms constituting the aromatic hydrocarbon ring or the polycyclic aromatic ring structure may be substituted with a substituent. Examples of the substituent include R 1 Examples of the substituent that may be possessed by the aliphatic hydrocarbon ring structure that gives the formula (I) include the same as those exemplified above. Among these, a fluorine atom, an alkyl group, or a fluorinated alkyl group is preferred, a fluorine atom, a methyl group, a tert-butyl group, or a trifluoromethyl group is more preferred, and a fluorine atom or a trifluoromethyl group is even more preferred.

[0200] R B3 , R B4 , R B5 , R B7 and R B8 Examples of the monovalent organic group having 1 to 20 carbon atoms represented by the formula (3-1) include R 4 Examples of the monovalent organic group having 1 to 20 carbon atoms and represented by the following formula include the same groups as those exemplified above.

[0201] R B3 , R B4 , R B5 , R B7 and R B8 is preferably a fluorine atom, an alkyl group or a fluorinated alkyl group, more preferably a fluorine atom, a methyl group, a tert-butyl group or a trifluoromethyl group, and even more preferably a fluorine atom or a trifluoromethyl group.

[0202] b1 is preferably 0 to 3, and more preferably 0 to 2. b1 is preferably 0 or 1. b1 is 1 or more, and n b1 is 0, then at least one R B3 is preferably attached in the para position relative to the sulfur atom.

[0203] b2 is preferably 0 to 3, more preferably 0 to 2. b2 is preferably 0 or 1. b2 is 1 or more, and n b2 is 0, then at least one R B4is preferably attached in the para position relative to the sulfur atom.

[0204] b3 is preferably 0 to 2, and more preferably 0 or 1. b3 As the number, 2 or 3 is preferred.

[0205] b4 is preferably 0 to 2, more preferably 0 or 1. When b4 is 1 or more, at least one R B7 is preferably bonded to the para position relative to the iodine atom. b5 is preferably 0 to 2, more preferably 0 or 1. When b5 is 1 or more, at least one R B8 is preferably attached in the para position relative to the iodine atom.

[0206] R B6 Examples of the divalent organic group represented by the formula (3-1) include R 4 Examples of the monovalent organic group having 1 to 20 carbon atoms and represented by the following formula (I) include groups in which one hydrogen atom has been removed from the groups exemplified above.

[0207] R B6 is preferably a single bond.

[0208] X + The monovalent radiation-sensitive onium cation represented by the following formula is preferably the cation (ra) or the cation (rc).

[0209] As the cation (ra), cations represented by the following formulas (ra-1) to (ra-9) (hereinafter also referred to as "cations (ra-1) to (ra-9)") are preferred.

[0210] [ka]

[0211] As the cation (rc), cations represented by the following formulas (rc-1) to (rc-4) (hereinafter also referred to as "cations (rc-1) to (rc-4)") are preferred. [ka]

[0212] As the compound [Z], a compound in which the above anion moiety and the above cation moiety are appropriately combined can be used.

[0213] <[B] Acid generator> The acid generator [B] is a radiation-sensitive acid generator other than the compound [Z]. The acid generator [B] is a compound that generates an acid upon irradiation. When the compound [Z] contained in composition (I) functions as an acid diffusion controller, composition (I) preferably contains the acid generator [B]. In this case, the acid generated from the acid generator [B] upon irradiation dissociates the acid-dissociable group (a) contained in the structural unit (I) of the polymer [A1] to generate a carboxyl group or the like, which results in a difference in the solubility of the resist film in a developer between the exposed and unexposed areas, thereby forming a resist pattern. The composition (I) may contain one or more acid generators [B].

[0214] The acid generator [B] is not particularly limited as long as it is a compound that does not fall under the category of the compound [Z] and is used as a radiation-sensitive acid generator. Examples of the acid generator [B] include onium salt compounds, N-sulfonyloxyimide compounds, sulfonimide compounds, halogen-containing compounds, and diazoketone compounds. Specific examples of the acid generator [B] include the compounds described in paragraphs 0080 to 0113 of JP-A-2009-134088.

[0215] The acid generator [B] is preferably an onium salt compound, more preferably a compound containing a radiation-sensitive onium cation moiety and a strong acid anion moiety, and even more preferably a compound containing a radiation-sensitive onium cation moiety and a sulfonic acid anion moiety. In other words, the acid generator [B] is more preferably a compound that generates a strong acid upon exposure, and even more preferably a compound that generates a sulfonic acid upon exposure.

[0216] Examples of the radiation-sensitive onium cation include the same monovalent radiation-sensitive onium cations as those exemplified in the above section <[Z] Compound>.

[0217] The anion portion of the strong acid may, for example, contain a sulfonate anion as the anion group.

[0218] The anion moiety preferably further has a ring structure, preferably a ring structure having 5 or more ring members.

[0219] Examples of ring structures having 5 or more ring members include alicyclic structures having 5 or more ring members, aliphatic heterocyclic structures having 5 or more ring members, aromatic hydrocarbon ring structures having 5 or more ring members, aromatic heterocyclic structures having 5 or more ring members, and combinations thereof.

[0220] In the ring structure, some or all of the hydrogen atoms bonded to the atoms constituting the ring structure may be substituted with a substituent. Examples of the substituent include R 2 Examples of the substituent that the aliphatic hydrocarbon ring structure that gives the following formula may have include the same as those exemplified above.

[0221] Examples of alicyclic structures having 5 or more ring members include monocyclic saturated alicyclic structures such as cyclopentane structure, cyclohexane structure, cycloheptane structure, cyclooctane structure, cyclononane structure, cyclodecane structure, and cyclododecane structure; monocyclic unsaturated alicyclic structures such as cyclopentene structure, cyclohexene structure, cycloheptene structure, cyclooctene structure, and cyclodecene structure; polycyclic saturated alicyclic structures such as norbornane structure, adamantane structure, tricyclodecane structure, tetracyclododecane structure, and steroid structure; and polycyclic unsaturated alicyclic structures such as norbornene structure and tricyclodecene structure. The term "steroid structure" refers to a structure having a basic skeleton (sterane skeleton) in which three six-membered rings and one four-membered ring are fused.

[0222] Examples of the aliphatic heterocyclic structure having 5 or more ring members include lactone structures such as a hexanolactone structure and a norbornanelactone structure; sultone structures such as a hexanosultone structure and a norbornanesultone structure; oxygen atom-containing heterocyclic structures such as a dioxolane structure, an oxacycloheptane structure and an oxanorbornane structure; nitrogen atom-containing heterocyclic structures such as an azacyclohexane structure and a diazabicyclooctane structure; and sulfur atom-containing heterocyclic structures such as a thiacyclohexane structure and a thianorbornane structure.

[0223] Examples of aromatic hydrocarbon ring structures having 5 or more ring members include a benzene structure; condensed polycyclic aromatic hydrocarbon ring structures such as a naphthalene structure, an anthracene structure, a fluorene structure, a biphenylene structure, a phenanthrene structure, and a pyrene structure; ring-assembled aromatic hydrocarbon ring structures such as a biphenyl structure, a terphenyl structure, a binaphthalene structure, and a phenylnaphthalene structure; and a 9,10-ethanoanthracene structure.

[0224] Examples of aromatic heterocyclic structures having 5 or more ring members include oxygen atom-containing heterocyclic structures such as a furan structure, a pyran structure, a benzofuran structure, and a benzopyran structure; nitrogen atom-containing heterocyclic structures such as a pyridine structure, a pyrimidine structure, and an indole structure; and sulfur atom-containing heterocyclic structures such as a thiophene structure.

[0225] The lower limit of the number of ring members in the ring structure is preferably 6, more preferably 8, still more preferably 9, and particularly preferably 10. The upper limit of the number of ring members is preferably 25.

[0226] The ring structure having 5 or more ring members is preferably an alicyclic structure or an aromatic hydrocarbon ring structure, more preferably a polycyclic saturated alicyclic structure, a benzene structure or a 9,10-ethanoanthracene structure, and even more preferably a steroid structure, a benzene structure or a 9,10-ethanoanthracene structure.

[0227] When the ring structure having 5 or more ring members is an aromatic hydrocarbon ring structure, it is preferable that some or all of the hydrogen atoms bonded to the carbon atoms constituting the ring structure are substituted with iodine atoms. In this case, the number of iodine atoms substituted is preferably 1 to 4, more preferably 1 to 3. The aromatic hydrocarbon ring structure is preferably a benzene structure or a naphthalene structure, more preferably a benzene structure.

[0228] As described above, the acid generator [B] is a compound different from the compound [Z], and therefore, the anion moiety preferably does not have the acid-dissociable group (z).

[0229] As the acid generator (B), a compound in which the above-mentioned radiation-sensitive onium cation moiety and the above-mentioned strong acid anion moiety are appropriately combined can be used.

[0230] As the acid generator [B], compounds represented by the following formulas (B-1) to (B-6) (hereinafter also referred to as "acid generators (B-1) to (B-6)") are preferred.

[0231] [ka]

[0232] In the above formulas (B-1) to (B-6), X + is a monovalent radiation-sensitive onium cation.

[0233] When composition (I) contains the acid generator [B], the lower limit of the content of the acid generator [B] in composition (I) is preferably 1 part by mass, more preferably 2 parts by mass, and even more preferably 3 parts by mass, relative to 100 parts by mass of the polymer [A1]. The upper limit of the content is preferably 30 parts by mass, more preferably 20 parts by mass, and even more preferably 10 parts by mass.

[0234] <[C] Acid diffusion controller> The acid diffusion controller [C] is an acid diffusion controller other than the compound [Z]. In particular, when the compound [Z] contained in composition (I) functions as a radiation-sensitive acid generator, composition (I) preferably contains the acid diffusion controller [C]. In this case, the acid diffusion controller [C] controls the diffusion phenomenon in the resist film of the acid generated from the compound [Z] upon exposure, thereby suppressing undesirable chemical reactions in unexposed areas. Composition (I) can contain one or more acid diffusion controllers [C].

[0235] Examples of the acid diffusion controller [C] include nitrogen atom-containing compounds, compounds that are photosensitive upon exposure to light and generate weak acids (hereinafter also referred to as "photodegradable bases"), etc. The acid diffusion controller [C] is preferably a photodegradable base.

[0236] Examples of the nitrogen atom-containing compound include amine compounds such as tripentylamine and trioctylamine, amide group-containing compounds such as formamide and N,N-dimethylacetamide, urea compounds such as urea and 1,1-dimethylurea, and nitrogen-containing heterocyclic compounds such as pyridine, N-(undecylcarbonyloxyethyl)morpholine, and Nt-pentyloxycarbonyl-4-hydroxypiperidine.

[0237] Examples of photodegradable bases include compounds containing a radiation-sensitive onium cation moiety and a weak acid anion moiety. The photodegradable base generates a weak acid in the exposed area to increase the solubility or insolubility of the polymer [A1] in a developer, thereby suppressing surface roughness in the exposed area after development. Meanwhile, in the unexposed area, the anion exerts a high acid-scavenging function, functioning as a quencher and capturing acid diffusing from the exposed area. In other words, because the base functions as a quencher only in the unexposed area, the contrast of the elimination reaction of the acid-dissociable group is improved, resulting in improved resolution.

[0238] Examples of the radiation-sensitive onium cation moiety include the same monovalent radiation-sensitive onium cations as those exemplified in the section <[Z] Compound>.

[0239] The anion portion of the weak acid may be, for example, a carboxylate anion (-COO - ) are included.

[0240] As described above, the acid diffusion controller [C] is a compound different from the compound [Z], and therefore, the anion moiety preferably does not have the acid-dissociable group (z).

[0241] As the photodegradable base, a compound in which the above-mentioned radiation-sensitive onium cation moiety and the above-mentioned weak acid anion moiety are appropriately combined can be used.

[0242] The acid diffusion controller [C] is preferably a compound represented by the following formulas (C-1) to (C-5) (hereinafter also referred to as "acid diffusion controllers (C-1) to (C-5)").

[0243] [ka]

[0244] In the above formulas (C-1) to (C-5), X + is a monovalent radiation-sensitive onium cation.

[0245] When composition (I) contains the acid diffusion controller [C], the lower limit of the content of the acid diffusion controller [C] in composition (I) is preferably 1 part by mass, more preferably 2 parts by mass, per 100 parts by mass of the polymer [A1], and the upper limit of the content is preferably 10 parts by mass, more preferably 5 parts by mass.

[0246] <[D] Organic Solvent> Composition (I) usually contains an organic solvent [D]. The organic solvent [D] is not particularly limited as long as it is a solvent that can dissolve or disperse at least the polymer [A1], the compound [Z], the acid generator [B], the acid diffusion controller [C], and other optional components that may be contained as needed.

[0247] Examples of the organic solvent [D] include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, etc. The composition (I) may contain one or more organic solvents [D].

[0248] Examples of alcohol-based solvents include aliphatic monoalcohol-based solvents having 1 to 18 carbon atoms, such as 4-methyl-2-pentanol, n-hexanol, and diacetone alcohol; alicyclic monoalcohol-based solvents having 3 to 18 carbon atoms, such as cyclohexanol; polyhydric alcohol-based solvents having 2 to 18 carbon atoms, such as 1,2-propylene glycol; and polyhydric alcohol partial ether-based solvents having 3 to 19 carbon atoms, such as propylene glycol monomethyl ether.

[0249] Examples of ether solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; and aromatic ring-containing ether solvents such as diphenyl ether and anisole.

[0250] Examples of ketone solvents include chain ketone solvents such as acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-iso-butyl ketone, and trimethylnonanone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone; 2,4-pentanedione, acetonylacetone, and acetophenone.

[0251] Examples of the amide solvent 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.

[0252] Examples of ester solvents include monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate, lactone solvents such as γ-butyrolactone and valerolactone, polyhydric alcohol carboxylate solvents such as propylene glycol acetate, polyhydric alcohol partial ether carboxylate 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.

[0253] 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.

[0254] [D] The organic solvent is preferably an alcohol solvent, a ketone solvent, an ester solvent, or a combination thereof; more preferably an aliphatic monoalcohol solvent having 1 to 18 carbon atoms, a polyhydric alcohol partial ether solvent having 3 to 19 carbon atoms, a cyclic ketone solvent, a monocarboxylic acid ester solvent, a lactone solvent, a polyhydric alcohol partial ether carboxylate solvent, or a combination thereof; and even more preferably diacetone alcohol, propylene glycol monomethyl ether, cyclohexanone, ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether acetate, or a combination thereof.

[0255] When composition (I) contains an organic solvent [D], the lower limit of the content of the organic solvent [D] is preferably 50 mass %, more preferably 60 mass %, even more preferably 70 mass %, and particularly preferably 80 mass %, based on all components contained in composition (I). The upper limit of the content is preferably 99.9 mass %, preferably 99.5 mass %, and more preferably 99.0 mass %.

[0256] <[F]polymer> The [F] polymer is a polymer different from the [A1] polymer and has a higher fluorine atom content than the [A1] polymer. Generally, polymers that are more hydrophobic than the base polymer tend to be unevenly distributed on the surface of the resist film. The [F] polymer has a higher fluorine atom content than the [A1] polymer, and this hydrophobicity-related characteristic tends to cause uneven distribution on the surface of the resist film. Consequently, when the [F] polymer is contained in the composition (I), the cross-sectional shape of the formed resist pattern is expected to be excellent. The composition (I) can contain the [F] polymer, for example, as a surface conditioner for the resist film. The composition (I) can contain one or more [F] polymers.

[0257] The lower limit of the fluorine atom content of the polymer [F] is preferably 1% by mass, more preferably 2% by mass, and even more preferably 3% by mass. The upper limit of the fluorine atom content is preferably 60% by mass, more preferably 50% by mass, and even more preferably 40% by mass. The fluorine atom content of the polymer is 13 The structure of the polymer is determined by C-NMR spectroscopy, and the molecular weight can be calculated from the structure.

[0258] The form of fluorine atoms contained in the [F] polymer is not particularly limited, and they may be bonded to either the main chain or the side chain of the [F] polymer. Regarding the form of fluorine atoms contained in the [F] polymer, it is preferable that the [F] polymer has a structural unit containing a fluorine atom (hereinafter also referred to as "structural unit (f)"). The [F] polymer may further have a structural unit other than the structural unit (f). The [F] polymer may have one or more types of each structural unit.

[0259] The lower limit of the Mw of the polymer [F] measured by GPC is preferably 2,000, more preferably 3,000, and even more preferably 5,000. The upper limit of the Mw is preferably 50,000, more preferably 20,000, and even more preferably 10,000.

[0260] The upper limit of the ratio of Mw to Mn (Mw / Mn) of the polymer [F] measured by GPC is preferably 5.0, more preferably 3.0, still more preferably 2.5, and particularly preferably 2.0. The lower limit of this ratio is usually 1.0, and preferably 1.2.

[0261] When composition (I) contains the polymer [F], the lower limit of the content of the polymer [F] is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, relative to 100 parts by mass of the polymer [A1], and the upper limit of the content is preferably 10 parts by mass, more preferably 5 parts by mass.

[0262] The polymer [F] can be synthesized, for example, by polymerizing the monomers that provide the respective structural units in a known manner, similar to the polymer [A1].

[0263] Each structural unit contained in the polymer [F] will be described below.

[0264] Structural Units (f) The structural unit (f) is a structural unit containing a fluorine atom. The fluorine atom content of the polymer [F] can be adjusted by adjusting the content of the structural unit (f) in the polymer [F]. Examples of the structural unit (F) include a structural unit represented by the following formula (f) (hereinafter also referred to as "structural unit (f-1)").

[0265] [ka]

[0266] In the above formula (f), R f1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. f is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2NH-, -CONH- or -OCONH-. f2 is a monovalent organic group having 1 to 20 carbon atoms and containing a fluorine atom.

[0267] R f1 From the viewpoint of copolymerizability of the monomer that gives the structural unit (f-1), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0268] L f As the alkyl group, —COO— is preferred.

[0269] R f2 Examples of the monovalent organic group having 1 to 20 carbon atoms and a fluorine atom represented by the formula (1) include R 1 , R 2 or R 3 Examples of the monovalent organic group having 1 to 20 carbon atoms represented by the following formula (I) include groups in which some or all of the hydrogen atoms in the groups exemplified as the monovalent organic group having 1 to 20 carbon atoms are substituted with fluorine atoms.

[0270] R f2 As the alkyl group, a group in which some or all of the hydrogen atoms of a monovalent chain hydrocarbon group having 1 to 20 carbon atoms have been substituted with fluorine atoms (a fluorinated chain hydrocarbon group) is preferred, and a monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms is more preferred.

[0271] When the polymer [F] has the structural unit (f), the lower limit of the content of the structural unit (f) is preferably 10 mol %, more preferably 20 mol %, and even more preferably 25 mol %, based on the total structural units constituting the polymer [F]. The upper limit of the content is, for example, 100 mol %.

[0272] (Other structural units) Examples of other structural units include structural units having an acid-dissociable group.

[0273] <Other optional ingredients> Examples of other optional components include surfactants, etc. Composition (I) may contain one or more other optional components.

[0274] <Composition (II)> Composition (II) contains [A2] a polymer and [B] an acid generator. Composition (II) usually contains [D] an organic solvent. Composition (II) may contain [C] an acid diffusion controller as a preferred component. Composition (II) may contain [F] a polymer as a preferred component. Composition (II) may contain other optional components as long as the effects of the present invention are not impaired.

[0275] Composition (II) contains the polymer [A2] and the acid generator [B], and therefore has excellent sensitivity, CDU performance, and development defect suppression. The reason why composition (II) exhibits the above-mentioned effects due to the above-mentioned configuration is not entirely clear, but it is presumed, for example, as follows. That is, the polymer [A2] has the above-mentioned structural unit (I) and structural unit (IIa), which improves the solubility or insolubility in the developer in the exposed area. As a result, composition (II) is thought to have excellent sensitivity, CDU performance, and development defect suppression.

[0276] The polymer [A2] is a polymer having the structural unit (I) and the structural unit (IIa) described above. In other words, the polymer [A2] is included in the polymer [A1], and the polymer [A1] having the structural unit (IIa) is the polymer [A2]. Therefore, the description in the above section on polymer [A1] is incorporated by reference for the parts of the polymer [A2] that are common to the polymer [A1].

[0277] In addition, with regard to the acid generator [B], organic solvent [D], acid diffusion controller [C], and other optional components contained in composition (II), the descriptions in the above <Composition (I)> section are incorporated by reference.

[0278] <Method for forming a resist pattern> The resist pattern forming method includes a step of applying a radiation-sensitive resin composition directly or indirectly to a substrate (hereinafter also referred to as a "coating step"), a step of exposing the resist film formed by the coating step (hereinafter also referred to as an "exposure step"), and a step of developing the exposed resist film (hereinafter also referred to as a "developing step").

[0279] In the coating step, the radiation-sensitive resin composition is either composition (I) or composition (II). Therefore, according to the method for forming a resist pattern, a resist pattern can be formed that has good sensitivity, excellent CDU, and suppresses the occurrence of development defects.

[0280] Each step of the resist pattern forming method will be described below.

[0281] [Coating process] In this step, the radiation-sensitive resin composition is applied directly or indirectly to a substrate, thereby forming a resist film directly or indirectly on the substrate.

[0282] In this step, the above composition (I) or composition (II) is used as the radiation-sensitive resin composition.

[0283] Examples of the substrate include conventionally known substrates such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Examples of indirectly coating the radiation-sensitive resin composition on a substrate include coating the radiation-sensitive resin composition on an anti-reflection film formed on a substrate. Examples of such anti-reflection films include organic or inorganic anti-reflection films disclosed in, for example, JP-B-6-12452 and JP-A-59-93448.

[0284] Examples of coating methods include spin coating, casting coating, and roll coating. After coating, if necessary, pre-baking (hereinafter also referred to as "PB") may be performed 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 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 time is preferably 600 seconds, more preferably 300 seconds. The lower limit of the average thickness of the formed resist 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.

[0285] [Exposure process] In this step, the resist film formed in the coating step is exposed to light. This exposure is carried out by irradiating the resist film through a photomask (or, in some cases, through an immersion medium such as water). Examples of the exposure light include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays, depending on the line width of the desired pattern. Among these, far ultraviolet light, EUV, or electron beams are preferred, with ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV (wavelength 13.5 nm), or electron beams being more preferred, and KrF excimer laser light, EUV, or electron beams being even more preferred, with EUV or electron beams being particularly preferred.

[0286] After the exposure, post-exposure baking (hereinafter also referred to as "PEB") is preferably performed to promote dissociation of acid-dissociable groups in the polymer [A1] or the like in the exposed portions of the resist film by the acid generated from the acid generator [B] or the like upon exposure. This PEB can increase the difference in solubility in a developer between the exposed and unexposed portions. 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 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.

[0287] [Development process] In this step, the exposed resist film is developed. This allows a predetermined resist pattern to be formed. After development, the resist film is generally washed with a rinse liquid such as water or alcohol, and then dried. The development method in the development step may be alkaline development or organic solvent development.

[0288] In the case of alkaline development, examples of the developer used for development include an alkaline aqueous solution containing at least one alkaline compound dissolved therein, such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (hereinafter also referred to as "TMAH"), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38 mass % TMAH solution is more preferred.

[0289] In the case of organic solvent development, examples of the developer include organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, as well as solutions containing the above organic solvents. Examples of the organic solvent include the solvents exemplified as the organic solvent [D] in the radiation-sensitive resin composition described above. Among these, ester solvents or ketone solvents are preferred. As the ester solvent, acetate ester solvents are preferred, and n-butyl acetate is more preferred. As the ketone solvent, chain ketones are preferred, and 2-heptanone is more preferred. The lower limit of the content of the organic solvent in the developer is preferably 80% by mass, more preferably 90% by mass, even more preferably 95% by mass, and particularly preferably 99% by mass. Examples of components other than the organic solvent in the developer include water and silicone oil.

[0290] Examples of development methods include the dip method, in which the substrate is immersed in a tank filled with developer for a certain period of time; the puddle method, in which developer is piled up on the surface of the substrate by surface tension and left to stand for a certain period of time to develop; the spray method, in which developer is sprayed onto the surface of the substrate; and the dynamic dispense method, in which developer is continuously dispensed while scanning a developer dispense nozzle at a constant speed over a substrate that is rotating at a constant speed.

[0291] Examples of patterns formed by the resist pattern forming method include line and space patterns and hole patterns.

[0292] <Polymer> This polymer is described as the polymer [A2] in the composition (II) above, and can be suitably used as a component of a radiation-sensitive resin composition. [Example]

[0293] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The methods for measuring the various physical properties are shown below.

[0294] [Weight average molecular weight (Mw), number average molecular weight (Mn) and polydispersity (Mw / Mn)] The Mw and Mn of the polymer were measured according to the conditions described above in the section "Method for measuring Mw and Mn." The polydispersity (Mw / Mn) of the polymer was calculated from the measurement results of Mw and Mn.

[0295] <Synthesis of Polymer [A]> [Synthesis Example] Synthesis of polymers (P-1) to (P-7) Each monomer was combined and copolymerized in tetrahydrofuran (THF) solvent, followed by crystallization in methanol. After repeated washing with hexane, the product was isolated and dried to obtain polymers represented by the following formulas (P-1) to (P-7) (hereinafter also referred to as "polymers (P-1) to (P-7)"). The composition of the obtained polymer [A] was: 1 It was measured by H-NMR. In the following formulas (P-1) to (P-7), the numerical value written to the lower right of each structural unit indicates the content (molar ratio) of each structural unit relative to all structural units constituting the polymer [A].

[0296] The Mw and Mw / Mn of the polymers (P-1) to (P-7) were as follows: P-1: Mw = 8,100, Mw / Mn = 1.7 P-2: Mw=8,300, Mw / Mn=1.7 P-3: Mw=8,200, Mw / Mn=1.7 P-4: Mw=8,600, Mw / Mn=1.7 P-5: Mw=9,700, Mw / Mn=1.7 P-6: Mw=8,300, Mw / Mn=1.6 P-7: Mw=9,200, Mw / Mn=1.7

[0297] [ka]

[0298] <Preparation of Radiation-Sensitive Resin Composition> The acid generator [B], acid diffusion controller [C], organic solvent [D], and polymer [F] used in preparing the radiation-sensitive resin composition are shown below. In the following examples and comparative examples, unless otherwise specified, "parts by mass" refers to a value when the mass of the polymer [A] used is taken as 100 parts by mass.

[0299] [[B] Acid generator] [B] As the acid generator, compounds represented by the following formulas (PAG1) to (PAG9) (hereinafter also referred to as "acid generators (PAG1) to (PAG9)") were used. Acid generators (PAG7) to (PAG9) correspond to the [Z] compound.

[0300] [ka]

[0301] [[C] Acid diffusion control agent] [C] The compounds represented by the following formulas (Q-1) to (Q-10) (hereinafter also referred to as "acid diffusion controllers (Q-1) to (Q-10)") were used as the acid diffusion controllers. Acid diffusion controllers (Q-6), (Q-7), (Q-9) and (Q-10) correspond to the [Z] compound.

[0302] [ka]

[0303] [[D] Organic solvent] [D] As the organic solvent, the following organic solvents were used. PGMEA: Propylene glycol monomethyl ether acetate GBL: gamma-butyrolactone CHN: Cyclohexane PGME: Propylene glycol monomethyl ether DAA: Diacetone alcohol EL: Ethyl lactate

[0304] [[F]polymer] As the polymer [F], a polymer represented by the following formula (F-1) (hereinafter also referred to as "polymer (F-1)") was used. In the following formula (F-1), the numerical value written to the lower right of each structural unit indicates the content ratio (molar ratio) of the structural unit relative to all structural units constituting the polymer [F]. The Mw and Mw / Mn of polymer (F-1) were as follows: F-1: Mw=8,900, Mw / Mn=2.0

[0305] [ka]

[0306] [Examples 1 to 14 and Comparative Examples 1 to 4] A surfactant (3M's "FC-4430") was dissolved in an organic solvent [D] shown in Table 1 at 100 ppm, and then each of the components shown in Table 1 was dissolved therein. The resulting mixture was filtered through a filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition.

[0307] <Evaluation> The radiation-sensitive resin compositions prepared above were evaluated for sensitivity, CDU performance, and development defect suppression according to the following methods. The evaluation results are shown in Table 1 below.

[0308] [sensitivity] A 12-inch silicon wafer was coated with a bottom anti-reflective coating composition (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. Each of the radiation-sensitive resin compositions prepared above was coated onto the bottom anti-reflective coating using the spin coater, followed by pre-baking at 130°C for 60 seconds. The coating was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 55 nm. This resist film was exposed to light using an EUV scanner (ASML's NXE3300, NA 0.33, σ 0.9 / 0.6, quadrupole-pole illumination, and a hole pattern mask with a 46 nm pitch on the wafer and +20% bias). Post-exposure baking (PEB) was performed on a hot plate at 120°C for 60 seconds, and development was performed in a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) for 30 seconds to form a resist pattern with 23 nm holes and a 46 nm pitch. The exposure dose for forming this resist pattern with 23 nm holes and a 46 nm pitch was determined as the optimal exposure dose (Eop [mJ / cm 2 The smaller the Eop value, the better the sensitivity.

[0309] [CDU performance] A resist pattern with 23 nm holes and a 46 nm pitch was formed using the exposure dose determined above and the same procedure as above. The formed resist pattern was observed from above using a scanning electron microscope (Hitachi High-Tech Corporation's "CG-5000") to measure the hole diameter at 16 points within a 500 nm range and calculate the average value. The average value was also measured at 500 arbitrary points. The 3 sigma value was calculated from the distribution of the measured values, and the calculated 3 sigma value was defined as CDU (unit: nm). The smaller the CDU value, the smaller the variation in hole diameter over a long period, indicating better CDU performance. The smaller the CDU value, the better the CDU performance.

[0310] [Development defect suppression] The composition for forming a bottom anti-reflective coating was applied to a 12-inch silicon wafer using the spin coater, and then heated at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. Each of the radiation-sensitive resin compositions prepared above was applied to this bottom anti-reflective coating using the spin coater, and post-baking was performed at 130°C for 60 seconds. This was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 55 nm. Next, this resist film was exposed to light using the EUV exposure system (ASML's "NXE3300") with NA=0.33, illumination conditions: Conventional s=0.89, and a mask: imecDEFECT32FFR02. After exposure, post-baking was performed at 120°C for 60 seconds. The resist film was then alkaline-developed using a 2.38 mass% TMAH aqueous solution as the alkaline developer. After development, the wafer was washed with water and then dried to form a positive resist pattern (32 nm line and space pattern), which was used as a wafer for defect inspection. The number of defects on this wafer for defect inspection was measured using a defect inspection system (KLA-Tencor's "KLA2810"). After development, the number of defects determined to be caused by the resist film was evaluated as "A" (very good) if the number was 15 or less, "B" (good) if it was more than 15 but not more than 40, and "C" (poor) if it was more than 40.

[0311] [Table 1]

Claims

1. a polymer having a first structural unit represented by the following formula (1), and whose solubility in a developer changes upon the action of an acid; A compound represented by the following formula (2): A radiation-sensitive resin composition comprising: 【Chemistry 1】 (In formula (1), R １ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ is a group in which two hydrogen atoms bonded to one carbon atom have been removed from a substituted or unsubstituted aliphatic hydrocarbon ring structure having 3 to 30 ring members. １ is a group in which one hydrogen atom has been removed from a substituted or unsubstituted aromatic hydrocarbon ring structure having 6 to 30 ring members. 【Chemistry 2】 (In formula (2), Z is an acid-dissociable group. L １ is *-O-CO- or -O-. * indicates the bonding site with Z. Y is an (n+1)-valent group represented by the following formula (Y-1). A － is a monovalent anionic group. n is an integer of 1 to 5. When n is 2 or more, two or more Z's may be the same or different, and two or more L's may be the same or different. １ are the same or different. ＋ is a monovalent radiation-sensitive onium cation. 【Transformation 3】 (In formula (Y-1), R Ａ１ is a group obtained by removing (n+b+1) hydrogen atoms from a ring structure other than a cyclic acetal structure. a is 1. R Ａ２ is a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, or a monovalent organic group having 1 to 10 carbon atoms. b is an integer of 0 to 5. When b is 2 or more, multiple R Ａ２ are the same or different. Ａ１ and L Ａ２ is a single bond or a divalent linking group. n is the same as n in the above formula (2). R Ａ３ and R Ａ４ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. c is an integer of 1 to 10. When c is 2 or more, multiple R Ａ３ are the same or different, and multiple R Ａ４ are the same or different. *1 is L in the above formula (2). １ *2 is the bonding site with A in the above formula (2). － )

2. A in the above formula (2) － But SO ３ － or COO － 2. The radiation-sensitive resin composition according to claim 1, wherein

3. R in the above formula (Y-1) Ａ１ 3. The radiation-sensitive resin composition according to claim 1, wherein the ring structure other than the cyclic acetal structure that gives the formula (I) is an aliphatic hydrocarbon ring structure, an aromatic hydrocarbon ring structure, an aromatic heterocyclic structure, an aliphatic heterocyclic structure other than a cyclic acetal, or a combination thereof.

4. 4. The radiation-sensitive resin composition according to claim 1, wherein the polymer further has a second structural unit represented by the following formula (3-1): 【Chemistry 4】 (In formula (3-1), R ３ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ is a single bond, —COO—, —O—, or —CONH—. ２ is a group obtained by removing (s+t+1) hydrogen atoms from an aromatic hydrocarbon ring structure having 6 to 30 ring members. s is an integer of 1 to 3. t is an integer of 0 to 8. When t is 1, R ４ is a halogen atom or a monovalent organic group having 1 to 20 carbon atoms. When t is 2 or more, a plurality of R ４ are the same or different and are a halogen atom or a monovalent organic group having 1 to 20 carbon atoms, or a plurality of R ４ Two or more of these are combined with each other to form an alicyclic structure having 4 to 20 ring members together with the carbon chain to which they are attached.)

5. In the above formula (3-1), when s is 1, the hydroxy group is Ar ２ Among the carbon atoms constituting L ２ and when s is 2 or more, at least one hydroxy group is bonded to a carbon atom adjacent to the carbon atom bonded to Ar ２ Among the carbon atoms constituting L ２ The radiation-sensitive resin composition according to claim 4 , wherein the carbon atom bonded to the radical is an alkyl group and the radical is an alkyl group.

6. a polymer having a first structural unit represented by the following formula (1) and a third structural unit represented by the following formula (3-2), and whose solubility in a developer changes due to the action of an acid; A radiation-sensitive acid generator A radiation-sensitive resin composition comprising: 【Transformation 5】 (In formula (1), R １ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ is a group in which two hydrogen atoms bonded to one carbon atom have been removed from a substituted or unsubstituted aliphatic hydrocarbon ring structure having 3 to 30 ring members. １ is a group in which one hydrogen atom has been removed from a substituted or unsubstituted aromatic hydrocarbon ring structure having 6 to 30 ring members. 【Transformation 6】 (In formula (3-2), R ３ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ is a single bond. ２ is a group obtained by removing (s+t+1) hydrogen atoms from an aromatic hydrocarbon ring structure having 6 to 30 ring members. s is an integer of 1 to 3. When s is 1, the hydroxy group is ２ Among the carbon atoms constituting L ２ When s is 2 or more, at least one hydroxy group is bonded to a carbon atom adjacent to the carbon atom bonded to Ar ２ Among the carbon atoms constituting L ２ and t is an integer of 0 to 8. When t is 1, R ４ is a halogen atom or a monovalent organic group having 1 to 20 carbon atoms. When t is 2 or more, a plurality of R ４ are the same or different and are a halogen atom or a monovalent organic group having 1 to 20 carbon atoms, or a plurality of R ４ Two or more of these are combined with each other to form an alicyclic structure having 4 to 20 ring members together with the carbon chain to which they are attached.)

7. a step of directly or indirectly applying the radiation-sensitive resin composition according to any one of claims 1 to 6 to a substrate; a step of exposing the resist film formed by the coating; developing the exposed resist film; A resist pattern forming method comprising:

8. A polymer having a first structural unit represented by the following formula (1) and a third structural unit represented by the following formula (3-2): 【Transformation 7】 (In formula (1), R １ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ is a group in which two hydrogen atoms bonded to one carbon atom have been removed from a substituted or unsubstituted aliphatic hydrocarbon ring structure having 3 to 30 ring members. １ is a group in which one hydrogen atom has been removed from a substituted or unsubstituted aromatic hydrocarbon ring structure having 6 to 30 ring members. 【Transformation 8】 (In formula (3-2), R ３ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ is a single bond. ２ is a group obtained by removing (s+t+1) hydrogen atoms from an aromatic hydrocarbon ring structure having 6 to 30 ring members. s is an integer of 1 to 3. When s is 1, the hydroxy group is ２ Among the carbon atoms constituting L ２ When s is 2 or more, at least one hydroxy group is bonded to a carbon atom adjacent to the carbon atom bonded to Ar ２ Among the carbon atoms constituting L ２ and t is an integer of 0 to 8. When t is 1, R ４ is a halogen atom or a monovalent organic group having 1 to 10 carbon atoms. When t is 2 or more, multiple R ４ are the same or different and are a halogen atom or a monovalent organic group having 1 to 10 carbon atoms, or a plurality of R ４ Two or more of these are combined with each other to form an alicyclic structure having 4 to 20 ring members together with the carbon chain to which they are attached.)

Images