Radiation-sensitive composition, resist pattern formation method, and polymer

Abstract

A radiation-sensitive composition comprising a polymer having: a side chain including an acid-dissociable group; and a side chain including one or more radiation-sensitive onium cation structures and two or more iodo groups.

Description

Radiation-sensitive composition, method for forming resist pattern, and polymer

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

[0002] Radiation-sensitive compositions used in microfabrication by lithography generate an 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 rays (EUV) (wavelength 13.5 nm), or charged particle rays such as electron beams, and a chemical reaction initiated by this acid causes a difference in the dissolution rate in a developer between exposed and unexposed areas, thereby forming a resist pattern on a substrate.

[0003] A radiation-sensitive composition is required to have good sensitivity to radiation such as extreme ultraviolet rays and electron beams, as well as excellent CDU (Critical Dimension Uniformity) performance.

[0004] In response to these requirements, the types and molecular structures of polymers, acid generators, and other components used in radiation-sensitive compositions have been investigated, and combinations thereof have also been investigated in detail (see JP-A-2010-134279, JP-A-2014-224984, JP-A-2016-047815, and JP-A-2021-009357).

[0005] JP 2010-134279 A JP 2014-224984 A JP 2016-047815 A JP 2021-009357 A

[0006]

[0003] As resist patterns become finer, the level of the above-mentioned performance requirements becomes higher, and a radiation-sensitive composition that satisfies these requirements is desired. In particular, since conventional radiation-sensitive compositions do not generate acid efficiently upon irradiation with radiation, a radiation-sensitive composition that has high radiation absorption efficiency is desired.

[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 composition and a method for forming a resist pattern that are excellent in sensitivity and CDU. Another object of the present invention is to provide a polymer that is suitable for the radiation-sensitive composition.

[0008] The invention made to solve the above-mentioned problems is a radiation-sensitive composition containing a polymer (hereinafter also referred to as "polymer [A]") having a side chain containing an acid-dissociable group, and a side chain containing two or more iodine groups and one or more radiation-sensitive onium cation structures.

[0009] Another invention made to solve the above-mentioned problems is a method for forming a resist pattern, comprising the steps of applying the radiation-sensitive composition described above directly or indirectly to a substrate, exposing the resist film formed by the application to light, and developing the exposed resist film.

[0010] Still another invention made to solve the above problems is a polymer having a side chain containing an acid-dissociable group, and a side chain containing two or more iodine groups and one or more radiation-sensitive onium cation structures.

[0011] The radiation-sensitive composition of the present invention has excellent sensitivity and CDU. According to the method for forming a resist pattern of the present invention, a resist pattern with excellent sensitivity and CDU can be formed. The polymer of the present invention is suitable as a polymer to be contained in a radiation-sensitive composition. Therefore, these can be suitably used in processing processes for semiconductor devices, which are expected to become even more miniaturized in the future.

[0012] The radiation-sensitive composition, method of forming a resist pattern, and polymer of the present invention will be described in detail below.

[0013] <Radiation-Sensitive Composition> The radiation-sensitive composition contains the polymer [A]. The radiation-sensitive composition usually contains an organic solvent (hereinafter also referred to as "organic solvent [D]"). The radiation-sensitive composition also preferably contains at least one selected from the group consisting of a radiation-sensitive acid generator (hereinafter also referred to as "acid generator [B]") and an acid diffusion controller (hereinafter also referred to as "acid diffusion controller [C]"). Furthermore, the radiation-sensitive composition may contain, as a suitable component, a polymer having a higher fluorine atom content than the polymer [A] (hereinafter also referred to as "polymer [F]"). The radiation-sensitive composition can contain other optional components as long as they do not impair the effects of the present invention.

[0014] The radiation-sensitive composition contains the polymer [A], which provides excellent sensitivity and CDU. The reason why the radiation-sensitive composition exhibits the above-described effects by having the above-described configuration is not entirely clear, but it is presumed, for example, as follows. That is, an iodo group has a high radiation absorption efficiency, and the presence of one or more radiation-sensitive onium cation structures and a side chain containing two or more iodo groups improves the efficiency of acid generation in exposed areas. As a result, the radiation-sensitive composition is thought to have excellent sensitivity and CDU.

[0015] The radiation-sensitive composition can be prepared, for example, by mixing (A) the polymer, and, if necessary, (B) the radiation-sensitive acid generator, (C) the acid diffusion controller, (D) the organic solvent, (F) the polymer and other optional components, etc., in a predetermined ratio, and then filtering the resulting mixture preferably through a filter with a pore size of 0.2 μm or less.

[0016] Each component contained in the radiation-sensitive composition will be described below.

[0017] <Polymer [A]> The side chain containing an acid-dissociable group in the polymer [A] is preferably contained in a first structural unit (hereinafter also referred to as "structural unit (I)") containing a partial structure in which a hydrogen atom of a carboxy group or a phenolic hydroxyl group is substituted with an acid-dissociable group. The side chain containing two or more iodine groups and one or more radiation-sensitive onium cation structures in the polymer [A] is preferably contained in a second structural unit (hereinafter also referred to as "structural unit (II)") containing two or more iodine groups and one or more radiation-sensitive onium cation structures. The polymer [A] is a polymer whose solubility in a developer changes under the action of acid. The polymer [A] exhibits the property of changing its solubility in a developer under the action of acid due to the side chain containing an acid-dissociable group. The radiation-sensitive composition may contain one or more types of polymer [A]. In this specification, a "structural unit" refers to one of the repeating units obtained by polymerizing a monomer, and is composed of a moiety constituting a part of the main chain and a side chain. "Main chain" refers to the longest atomic chain that constitutes a polymer. "Side chain" refers to an atomic chain that constitutes a polymer other than the main chain. "Partial structure" refers to a part of a structure contained in a side chain or a structural unit.

[0018] The polymer [A] preferably further has a side chain containing a phenolic hydroxyl group. The side chain containing a phenolic hydroxyl group is preferably contained in a third structural unit containing a phenolic hydroxyl group (hereinafter also referred to as "structural unit (III)"). The polymer [A] may further have other structural units (hereinafter also referred to as "other structural units") other than the structural units (I) to (III). The polymer [A] can have one or more types of each structural unit.

[0019] The lower limit of the content of the polymer (A) in the radiation-sensitive composition is preferably 50% by mass, more preferably 70% by mass, and even more preferably 80% by mass, based on all components other than the organic solvent (D) contained in the radiation-sensitive composition, and the upper limit of the content is preferably 99% by mass, more preferably 95% by mass.

[0020] The lower limit of the weight average molecular weight (Mw) of the polymer [A], as measured by gel permeation chromatography (GPC) in terms of polystyrene, is preferably 1,000, more preferably 2,000, and even more preferably 3,000. The upper limit of the Mw is preferably 30,000, more preferably 20,000, and even more preferably 10,000. By setting the Mw of the polymer [A] within the above range, the coatability of the radiation-sensitive composition can be improved. The Mw of the polymer [A] can be adjusted, for example, by adjusting the type and amount of polymerization initiator used in the synthesis.

[0021] The upper limit of the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the polymer (A) as determined by GPC (hereinafter also referred to as "Mw / Mn" or "polydispersity") is preferably 2.5, more preferably 2.0, and even more preferably 1.7. The lower limit of the ratio is usually 1.0, preferably 1.1, more preferably 1.2, and even more preferably 1.3.

[0022] [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", one "G3000HXL", and one "G4000HXL" manufactured by Tosoh Corporation Column temperature: 40°C Elution solvent: tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection amount: 100 μL Detector: differential refractometer Standard material: monodisperse polystyrene

[0023] The polymer (A) can be synthesized, for example, by polymerizing monomers that provide the respective structural units by a known method.

[0024] Each structural unit contained in the polymer (A) will be described below.

[0025] [Structural Unit (I)] The side chain containing an acid-dissociable group that the polymer (A) has is preferably contained in a structural unit (first structural unit, also referred to as structural unit (I)) that includes a partial structure in which a hydrogen atom of a carboxy group or a phenolic hydroxyl group is substituted with an acid-dissociable group.

[0026] The term "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group or a phenolic hydroxyl group, and dissociates under the action of an acid to give a carboxy group or a phenolic hydroxyl group.

[0027] When the polymer [A] contains the structural unit (I), an acid-dissociable group dissociates from the structural unit (I) due to the action of an acid generated from the polymer [A] or the like upon exposure, and this results in a difference in solubility of the polymer [A] in a developer between an exposed portion and a non-exposed portion, allowing the formation of a resist pattern.

[0028] The structural unit (I) is not particularly limited as long as it is a structural unit that dissociates under the action of an acid to give a carboxy group or a phenolic hydroxyl group. Among these, a structural unit containing a partial structure substituted with an acid-dissociable group represented by the following formula (1-1) (acid-dissociable group (a-1)) or an acid-dissociable group represented by the following formula (1-2) (acid-dissociable group (a-2)) is preferred. Hereinafter, the acid-dissociable group (a-1) and the acid-dissociable group (a-2) may be collectively referred to as the acid-dissociable group (a). The acid-dissociable group (a) is a group that substitutes a hydrogen atom of the carboxy group or the phenolic hydroxyl group in the structural unit (I). In other words, in the structural unit (I), the acid-dissociable group (a) is bonded to the etheric oxygen atom of the carbonyloxy group or the oxygen atom of the phenolic hydroxyl group. The term "phenolic hydroxyl group" refers not only to a hydroxy group directly bonded to a benzene ring, but also to hydroxy groups directly bonded to aromatic rings in general.

[0029]

[0030] In the above formula (1-1), Ar １ R is a group in which one hydrogen atom has been removed from a substituted or unsubstituted aromatic ring structure having 5 to 30 ring members. １ and R ２ are each independently a substituted or unsubstituted monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or R １ and R ２ and are combined together. １together with the carbon atom to which it is bonded, forms a saturated alicyclic hydrocarbon ring having 3 to 8 carbon atoms. * indicates the bonding site with the etheric oxygen atom of the carboxy group or the oxygen atom of the phenolic hydroxyl group.

[0031]

[0032] In the above formula (1-2), R ｖ１ ~R ｖ３ are each independently a hydrogen atom or a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 10 carbon atoms. s is 1 or 2. * indicates the bonding site with the etheric oxygen atom of the carboxy group or the oxygen atom of the phenolic hydroxyl group.

[0033] "Number of ring members" refers to the number of atoms constituting the ring structure, and in the case of a polycyclic ring, it refers to the number of atoms constituting the polycyclic ring. "Polycyclic ring" includes not only spiro-type polycyclic rings in which two rings share one shared atom and fused polycyclic rings in which two rings share two shared atoms, but also ring assembly-type polycyclic rings 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". Among alicyclic structures, polycyclic rings containing an aliphatic hydrocarbon ring structure and an aliphatic heterocyclic structure are considered to be "aliphatic heterocyclic structures". "Aromatic ring structure" includes "aromatic hydrocarbon ring structure" and "aromatic heterocyclic structure". Among aromatic ring structures, polycyclic rings containing an aromatic hydrocarbon ring structure and an aromatic heterocyclic structure are considered to be "aromatic heterocyclic structures". The term "a group in which X hydrogen atoms have been removed from a ring structure" refers to a group in which X hydrogen atoms bonded to atoms constituting the ring structure have been removed.

[0034] "Number of carbon atoms" refers to the number of carbon atoms constituting the group. "Hydrocarbon group" includes "aliphatic hydrocarbon group" and "aromatic hydrocarbon group". "Aliphatic hydrocarbon group" includes "saturated hydrocarbon group" and "unsaturated hydrocarbon group". From another perspective, "aliphatic hydrocarbon group" includes "chain hydrocarbon group" and "alicyclic hydrocarbon group". "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. "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. "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.

[0035] Ar １ Examples of aromatic ring structures having 5 to 30 ring members that give the above formula include aromatic hydrocarbon ring structures having 6 to 30 ring members and aromatic heterocyclic structures having 5 to 30 ring members.

[0036] Examples of aromatic hydrocarbon ring structures having 6 to 30 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; and ring-assembly aromatic hydrocarbon ring structures such as a biphenyl structure, a terphenyl structure, a binaphthalene structure, and a phenylnaphthalene structure.

[0037] Examples of the aromatic heterocyclic structure having 5 to 30 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 pyrrole structure, a pyridine structure, a pyrimidine structure, an indole structure, and a quinoline structure; and sulfur atom-containing heterocyclic structures such as a thiophene structure and a dibenzothiophene structure.

[0038] Ar １The aromatic ring structure having 5 to 30 ring members that gives the formula (I) is preferably an aromatic hydrocarbon ring structure having 6 to 30 ring members, more preferably a benzene structure or a condensed polycyclic aromatic hydrocarbon ring structure, and even more preferably a benzene structure or a naphthalene structure.

[0039] 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 halogen atoms such as fluorine atoms and iodine atoms, hydroxy groups, carboxy groups, cyano groups, nitro groups, alkyl groups described below, fluorinated alkyl groups (groups in which some or all of the hydrogen atoms of an alkyl group are substituted with fluorine atoms), alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, and oxo groups (=O). Among these, halogen atoms, alkyl groups, fluorinated alkyl groups, and alkoxy groups are preferred, and fluorine atoms, iodine atoms, methyl groups, trifluoromethyl groups, and methoxy groups are more preferred. When the substituent is a fluorine atom or iodine atom, the sensitivity of the radiation-sensitive composition may be further improved.

[0040] R １ and R ２ Examples of the monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms that gives the formula (I) include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group; alkenyl groups such as an ethenyl group, a propenyl group, a butenyl group, and a 2-methylprop-1-en-1-yl group; and alkynyl groups such as an ethynyl group, a propynyl group, and a butynyl group.

[0041] R １ and R ２ and are combined together. １ Examples of the monovalent saturated alicyclic hydrocarbon ring having 3 to 8 carbon atoms formed together with the carbon atom to which is bonded include monocyclic alicyclic saturated hydrocarbon rings such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring; polycyclic alicyclic saturated hydrocarbon rings such as a norbornane ring and an adamantane ring; monocyclic alicyclic unsaturated hydrocarbon rings such as a cyclopentene ring and a cyclohexene ring; and polycyclic alicyclic unsaturated hydrocarbon rings such as a norbornene ring.

[0042] R １ and R ２ The aliphatic hydrocarbon group that provides the formula (I) is preferably a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, more preferably an alkyl group or a monocyclic alicyclic saturated hydrocarbon group, and even more preferably a methyl group, an ethyl group, an i-propyl group, or a cyclopropyl group.

[0043] A part or all of the hydrogen atoms in the aliphatic hydrocarbon group may be substituted with a substituent. Examples of the substituent include Ar. １ Examples of the substituent include the same groups as those exemplified as the substituent that may be possessed by the above ring structure that gives the following formula: Preferred as the substituent are a halogen atom and an alkoxy group, and more preferred is an iodine atom.

[0044] R １ and R ２ and are combined together. １ When forming a saturated alicyclic hydrocarbon ring having 3 to 8 carbon atoms together with the carbon atom to which it is bonded, examples of the alicyclic hydrocarbon ring include monocyclic saturated alicyclic hydrocarbon rings such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring; and polycyclic saturated alicyclic hydrocarbon rings such as a norbornane ring and an adamantane ring. Among these, a monocyclic saturated alicyclic hydrocarbon ring having 5 or 6 carbon atoms is preferred.

[0045] The acid-dissociable group (a) is preferably a group that substitutes a hydrogen atom of a carboxy group in the structural unit (I). In other words, in the structural unit (I), the acid-dissociable group (a) is preferably bonded to an etheric oxygen atom of a carbonyloxy group.

[0046] The acid-dissociable group (a-1) is preferably a group represented by the following formulas (a-1-1) to (a-1-24).

[0047]

[0048]

[0049] In the above formulas (a-1-1) to (a-1-24), * has the same meaning as in the above formula (1-1).

[0050] Rｖ１ ~R ｖ３ As the monovalent chain hydrocarbon group having 1 to 10 carbon atoms which gives １ and R ２ Examples of the monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms include the same groups as those exemplified above.

[0051] The acid-dissociable group (a-2) is preferably a group represented by the following formulas (a-2-1) to (a-2-2).

[0052]

[0053] In the above formulas (a-2-1) to (a-2-2), * has the same meaning as in the above formula (1-2).

[0054] The structural unit (I) may contain an acid-dissociable group other than the acid-dissociable group (a) (hereinafter also referred to as "acid-dissociable group (b)").

[0055] The polymer (A) has an acid-dissociable group (b), which allows adjustment of the balance between sensitivity and CDU.

[0056] The acid-dissociable group (b) is not particularly limited as long as it is a group other than the acid-dissociable group (a), and examples thereof include acid-dissociable groups represented by the following formulae (b-1) to (b-3) (hereinafter also referred to as "acid-dissociable groups (b-1) to (b-3)"):

[0057]

[0058] In the above formulas (b-1) to (b-3), * indicates the bonding site with the etheric oxygen atom of the carboxy group or the oxygen atom of the phenolic hydroxyl group.

[0059] In the above formula (b-1), R Ｘ R is a substituted or unsubstituted monovalent saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. Ｙ and R Ｚ are each independently a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a combination of these groups and the carbon atoms to which they are bonded to form a saturated alicyclic structure having 3 to 20 ring members.

[0060] In the above formula (b-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.

[0061] In the above formula (b-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, and R Ｗ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R Ｕ and R Ｗ are aligned with each other and R Ｕ and the carbon atom to which R Ｗ forms an aliphatic heterocyclic structure having 4 to 20 ring members together with the oxygen atom to which it is bonded, and R Ｖ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0062] R Ｙ or R Ｚ Examples of the monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) 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] R Ｘ Examples of the monovalent saturated aliphatic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include alkyl groups having 3 to 20 carbon atoms among those exemplified above as the alkyl groups.

[0064] R Ｘ , R Ｙ or R Ｚ The monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (1-1) is R １ and R ２ Examples include those similar to those described above.

[0065] 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. Examples of the saturated alicyclic structure include monocyclic saturated alicyclic hydrocarbon rings such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring; and polycyclic saturated alicyclic saturated hydrocarbon rings such as a norbornane ring and an adamantane ring.

[0066] 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 (I) include a monovalent aliphatic 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.

[0067] The monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms includes the above-mentioned R Ｘ Examples include those similar to those described above.

[0068] The monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms includes R １ and R ２ Examples include those similar to those described above.

[0069] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, a naphthylmethyl group, and an anthrylmethyl group.

[0070] The above R Ｘ Examples of the substituent that the aliphatic hydrocarbon group represented by the formula (1-1) may have include Ar１ Examples of the substituent that the above ring structure that gives the following formula may have include the same groups as those exemplified above.

[0071] R Ｄ Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include the above-mentioned R Ｙ , R Ｚ , R Ｂ , R Ｃ , R Ｕ , R Ｖ or R Ｗ and groups in which one hydrogen atom has been removed from the groups exemplified as monovalent hydrocarbon groups having 1 to 20 carbon atoms, represented by the following formula:

[0072] R Ａ , R Ｂ and R Ｃ and the carbon atom to which R is bonded. Ｄ Examples of the unsaturated alicyclic structure having 4 to 20 ring members constituted by the above 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.

[0073] R Ｕ and R Ｗ are aligned with each other and R Ｕ and the carbon atom to which R Ｗ Examples of the aliphatic heterocyclic structure having 4 to 20 ring members that is formed together with the oxygen atom to which it 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.

[0074] 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 chain hydrocarbon group is preferable, an alkyl group is more preferable, and a methyl group is even more preferable.

[0075] R Ｙand R Ｚ When R 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, more preferably a cyclopentane structure or a cyclohexane structure. Ｘ 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.

[0076] R Ｙ and R Ｚ It is preferable that these are combined with each other to form, together with the carbon atoms to which they are bonded, a saturated alicyclic structure having 3 to 20 ring members, in which case the CDU of the radiation-sensitive composition can be further improved.

[0077] R Ｂ is preferably a hydrogen atom.

[0078] R Ｃ is preferably a hydrogen atom or a chain hydrocarbon group, more preferably a hydrogen atom or an alkyl group, and even more preferably a methyl group.

[0079] R Ａ , R Ｂ and R Ｃ and the carbon atom to which R is bonded. Ｄ The unsaturated alicyclic structure having 4 to 20 ring members constituted by both of the above is preferably a monocyclic unsaturated alicyclic structure, more preferably a cyclopentane structure or a cyclohexene structure.

[0080] The acid-dissociable group (b) is preferably the acid-dissociable group (b-1) or (b-2).

[0081] Examples of the acid-dissociable group (b-1) include groups represented by the following formulae (b-1-1) to (b-1-13): Examples of the acid-dissociable group (b-2) include groups represented by the following formulae (b-2-1) to (b-2-2):

[0082]

[0083] In the above formulas (b-1-1) to (b-1-13) and (b-2-1) to (b-2-2), * has the same meaning as in the above formulas (b-1) and (b-2).

[0084] Examples of the structural unit (I) include structural units represented by the following formula (3-1) or (3-2) (hereinafter also referred to as "structural unit (I-1) or (I-2)").

[0085]

[0086] In the above formulas (3-1) and (3-2), Z represents an acid-dissociable group. Z is preferably an acid-dissociable group represented by the above formula (1-1) or (1-2) (acid-dissociable group (a-1) or acid-dissociable group (a-2)), or an acid-dissociable group represented by the above formulas (b-1) to (b-2) (acid-dissociable groups (b-1) to (b-2)).

[0087] In the above formula (3-1), R １１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ３１ is a divalent linking group. ３１ is 0 or 1.

[0088] R ３１ As the divalent linking group in ｓ and Q ｓ Among them, divalent hydrocarbon groups having 1 to 10 carbon atoms are preferred, and alkylene groups are more preferred.

[0089] In the above formula (3-2), R １２ is a hydrogen atom or a methyl group. １３ is a single bond, an oxygen atom, —COO— or —CONH—. ２ R is a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring structure having 6 to 30 ring members. １４ is a single bond or —CO—.

[0090] R １１ 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 methyl group is more preferred.

[0091] R１３ is preferably a single bond.

[0092] Ar ２ Examples of aromatic hydrocarbon ring structures having 6 to 30 ring members that give the following formula (1-1) include Ar １ Among the aromatic ring structures having 5 to 30 ring members that give the above formula, the same structures as those exemplified as the aromatic hydrocarbon ring structures having 6 to 30 ring members can be mentioned. Among them, a benzene structure or a naphthalene structure is preferred.

[0093] R １４ is preferably a single bond.

[0094] The structural unit (I) is preferably the structural unit (I-1).

[0095] The lower limit of the content of the structural unit (I) in the polymer [A] is preferably 5 mol%, more preferably 15 mol%, even more preferably 20 mol%, and particularly preferably 25 mol%, based on all structural units constituting the polymer [A]. The upper limit of the content is preferably 70 mol%, more preferably 60 mol%, even more preferably 50 mol%, and particularly preferably 40 mol%. By setting the content of the structural unit (I) within the above range, the sensitivity and CDU of the radiation-sensitive composition can be further improved. Unless otherwise specified, the descriptions of the upper and lower limits of numerical ranges in this specification may indicate that the upper limit is "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.

[0096] The lower limit of the content of the structural unit having the acid-dissociable group (a) among the structural units (I) in the polymer [A] is 0 mol%, preferably 15 mol%, preferably 30 mol%, more preferably 45 mol%, even more preferably 60 mol%, and particularly preferably 75 mol%, relative to the content of the structural unit (I). The upper limit of the content is 100 mol%, preferably 85 mol%, preferably 70 mol%, more preferably 55 mol%, even more preferably 40 mol%, and particularly preferably 25 mol%, relative to the content of the structural unit (I).

[0097] The lower limit of the content of the structural unit having an acid-dissociable group containing an iodine group among the structural units (I) in the polymer [A] is 0 mol%, preferably 15 mol%, preferably 30 mol%, more preferably 45 mol%, even more preferably 60 mol%, and particularly preferably 75 mol%, relative to the content of the structural unit (I). The upper limit of the content is 100 mol%, preferably 85 mol%, preferably 70 mol%, more preferably 55 mol%, even more preferably 40 mol%, and particularly preferably 25 mol%, relative to the content of the structural unit (I).

[0098] The polymer [A] having the structural unit (I) can be synthesized by polymerizing a monomer that provides the structural unit (I) by a known method.

[0099] [Structural Unit (II)] The side chain containing two or more iodine groups and one or more radiation-sensitive onium cation structures that the polymer (A) has is preferably contained in a structural unit containing two or more iodine groups and one or more radiation-sensitive onium cation structures (second structural unit, also referred to as structural unit (II)). The structural unit (II) can also be said to be a structural unit containing a partial structure that generates an acid upon irradiation with radiation (hereinafter also referred to as "exposure").

[0100] The number of iodo groups in the structural unit (II) may be two or more, preferably from two to six, more preferably from two to four, and even more preferably two or three.

[0101] At least one of the iodo groups in the structural unit (II) is preferably bonded to an aromatic ring structure. １ Examples of the aromatic ring structure having 5 to 30 ring members that provides the formula (I) include the same as those exemplified above. Among these, an aromatic hydrocarbon ring structure having 6 to 30 ring members is preferred, an aromatic hydrocarbon ring structure having 6 to 10 ring members is more preferred, and a benzene ring is even more preferred. It is not necessary for two or more iodo groups to be bonded to the same aromatic ring structure, and two or more aromatic ring structures each having one iodo group bonded thereto may be included.

[0102] Examples of the structural unit (II) include a structure containing a sulfonate anion and a radiation-sensitive onium cation, with the sulfonate anion bonded to a side chain of a polymer (hereinafter also referred to as "Structure 1"), and a structure containing a sulfonate anion and a radiation-sensitive onium cation, with the radiation-sensitive onium cation bonded to a side chain of a polymer (hereinafter also referred to as "Structure 2"). Of these, Structure 1 is preferred.

[0103] Examples of the radiation-sensitive onium cation include the same as those exemplified as the radiation-sensitive onium cation in the photodegradable base used in the acid generator [B] and the acid diffusion controller [C] described below. Among these, sulfonium cations are preferred, and monovalent radiation-sensitive sulfonium cations containing an aromatic ring structure in which at least one hydrogen atom is substituted with at least one group selected from the group consisting of a fluorine atom, a fluorine-containing group, and an iodine atom are preferred. For specific and preferred embodiments, the description of the radiation-sensitive onium cation described in the acid generator [B] described below is incorporated by reference.

[0104] The structural unit (II) is preferably the above-mentioned structure 1, and examples thereof include a structural unit containing a partial structure represented by the following formula (II-0).

[0105]

[0106] In the above formula (II-0), R ｇ１ and R ｇ２ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ｇ is an integer from 1 to 10. ０＋ is a monovalent radiation-sensitive onium cation. * is a bond to another partial structure in the structural unit (II).

[0107] R ｇ１ and R ｇ２ Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula (R) include a fluorinated alkyl group having 1 to 20 carbon atoms. ｇ１ and R ｇ２As the alkyl group, a fluorine atom or a fluorinated alkyl group having 1 to 6 carbon atoms is preferred, a fluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms is more preferred, a fluorine atom or a trifluoromethyl group is even more preferred, and a fluorine atom is particularly preferred.

[0108] n ｇ is preferably 1 to 4, and more preferably 1 or 2.

[0109] The structural unit (II) can be obtained by polymerizing a (meth)acrylic acid ester compound containing two or more iodo groups and one or more radiation-sensitive onium cation structures (hereinafter also referred to as compound (II-1)), or a vinyl compound containing two or more iodo groups and one or more radiation-sensitive onium cation structures (hereinafter also referred to as compound (II-2)).

[0110] Examples of compound (II-1) include a monomer that is a salt containing a sulfonate anion having a (meth)acryloyloxy group and two or more iodo groups, and a radiation-sensitive onium cation (hereinafter also referred to as monomer (II-1-1)); a monomer that is a salt containing a sulfonate anion having a (meth)acryloyloxy group and one iodo group, and a radiation-sensitive onium cation having one iodo group (hereinafter also referred to as monomer (II-1-2)); and a monomer that is a salt containing a sulfonate anion having a (meth)acryloyloxy group, and a radiation-sensitive onium cation having two or more iodo groups (hereinafter also referred to as monomer (II-1-3)). Of these, monomer (II-1-1) is preferred.

[0111] Examples of the sulfonate anion in the monomer (II-1-1) include a sulfonate anion containing an aromatic ring having two or more iodine groups bonded thereto and one (meth)acryloyloxy group; and a sulfonate anion containing two or more aromatic rings having one iodine group bonded thereto and one (meth)acryloyloxy group. The upper limit of the iodine atom content in these sulfonate anions is preferably 50% or less, more preferably 45% or less, even more preferably 40% or less, and particularly preferably 35% or less, based on the molecular weight of the sulfonic acid having a proton bonded to the sulfonate anion. The lower limit of the content is preferably 10% or more, more preferably 20% or more, and even more preferably 25% or more.

[0112] Examples of compound (II-2) include a monomer that is a salt containing a sulfonate anion having a vinyl group and two or more iodine groups, and a radiation-sensitive onium cation (hereinafter also referred to as monomer (II-2-1)); a monomer that is a salt containing a sulfonate anion having a vinyl group and one iodine group, and a radiation-sensitive onium cation having one iodine group (hereinafter also referred to as monomer (II-2-2)); and a monomer that is a salt containing a sulfonate anion having a vinyl group, and a radiation-sensitive onium cation having two or more iodine groups (hereinafter also referred to as monomer (II-2-3)). Of these, monomer (II-2-1) is preferred.

[0113] Examples of the sulfonate anion in the monomer (II-2-1) include a sulfonate anion containing an aromatic ring having two or more iodine groups bonded thereto and one vinyl group; and a sulfonate anion containing two or more aromatic rings having one iodine group bonded thereto and one vinyl group. The upper limit of the iodine atom content in these sulfonate anions is preferably 50% or less, more preferably 45% or less, even more preferably 40% or less, and particularly preferably 35% or less, based on the molecular weight of the sulfonic acid having a proton bonded to the sulfonate anion. The lower limit of the content is preferably 10% or more, more preferably 20% or more, even more preferably 25% or more, and particularly preferably 30% or more.

[0114] Examples of the compound (II-1) include compounds represented by the following formula (II-1s):

[0115]

[0116] In the above formula (II-1s), R ｓ is a hydrogen atom or a methyl group. ｓ and Q ｓ is a single bond or a divalent linking group. ｓ is a group having 6 to 20 carbon atoms (m ｓ +p ｓ +2)valent aromatic hydrocarbon group. ｓ１ and R ｓ２ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ｓ３ is a substituent other than an iodo group. ｓ is an integer from 0 to 4. ｓ is an integer from 1 to 10. ｓ is an integer equal to or greater than 0. ｓ＋ is a monovalent radiation-sensitive onium cation, ｓ If is 0, L ｓ contains an aromatic ring having two or more iodo groups, or contains two or more aromatic rings having one iodo group. ｓ If is 1, L ｓ contains an aromatic ring bearing one or more iodo groups.

[0117] L ｓ and Q ｓ Examples of the divalent linking group represented by the formula (I) include a carbonyl group, an ether group, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, a divalent hydrocarbon group, or a group formed by combining these groups. A carbon atom constituting the divalent hydrocarbon group may be substituted with a carbonyl group or an ether group. ｓ is preferably a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms. ｓis preferably a group in which one or more carbon atoms selected from the group consisting of a carbonyl group, an ether group, a carbonyloxy group, and a divalent hydrocarbon group having 1 to 20 carbon atoms are combined, and a carbon atom constituting the divalent hydrocarbon group having 1 to 20 carbon atoms may be substituted with a carbonyl group or an ether group.

[0118] In addition, m ｓ If is 0, L ｓ contains an aromatic ring having two or more iodo groups, or contains two or more aromatic rings having one iodo group. ｓ If is 1, L ｓ contains an aromatic ring having one or more iodo groups. Examples of such aromatic rings having an iodo group include an iodophenylene group, an iodotolylene group, an iodonaphthylene group, a diiodophenylene group, and a diiodonaphthylene group. The aromatic ring may further have a substituent, and examples of such a substituent include a fluoro group, a chloro group, a bromo group, an alkoxy group, a hydroxy group, a carboxy group, and a nitro group.

[0119] Ar ｓ (m ｓ +p ｓ Examples of aromatic hydrocarbon rings having 6 to 20 carbon atoms that provide a divalent aromatic hydrocarbon group include a benzene ring; condensed polycyclic aromatic hydrocarbon rings such as a naphthalene ring, an anthracene ring, a fluorene ring, a biphenylene ring, a phenanthrene ring, and a pyrene ring; ring assembly aromatic hydrocarbon rings such as a biphenyl ring, a terphenyl ring, a binaphthalene ring, and a phenylnaphthalene ring; a 9,10-ethanoanthracene ring; and a triptycene ring. Of these, a benzene ring and a naphthalene ring are preferred. ｓ may have a substituent, and examples of such a substituent include a halogen atom, an alkoxy group, a hydroxy group, a carboxy group, and a nitro group.

[0120] R ｓ１ and R ｓ２ Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula (R) include a fluorinated alkyl group having 1 to 20 carbon atoms. ｓ１ and R ｓ２As the alkyl group, a fluorine atom or a fluorinated alkyl group is preferable, a fluorine atom or a perfluoroalkyl group is more preferable, a fluorine atom or a trifluoromethyl group is further preferable, and a fluorine atom is particularly preferable.

[0121] R ｓ３ Examples of the substituent other than the iodo group represented by the formula (I) include a fluoro group, a chloro group, a bromo group, an alkoxy group, a hydroxy group, a carboxy group, and a nitro group.

[0122] m ｓ As the number, 2 or 3 is preferred.

[0123] n ｓ is preferably 1 to 4, and more preferably 1 or 2.

[0124] M ｓ＋ Examples of the radiation-sensitive onium cation include those similar to those described below as the radiation-sensitive onium cation.

[0125] Compound (II-1) is preferably a compound represented by the following formulas (II-1-1) to (II-1-10).

[0126]

[0127]

[0128]

[0129] In the above formulas (II-1-1) to (II-1-10), M ｓ＋ has the same meaning as the above formula (II-1s).

[0130] Examples of the compound (II-2) include compounds represented by the following formula (II-2t) or (II-2u).

[0131]

[0132] In the above formula (II-2t), Q ｔ is a single bond or a divalent linking group. ｔ is a group having 6 to 20 carbon atoms (m ｔ +p ｔ +1)-valent aromatic hydrocarbon group. ｔ１ and R ｔ２are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ｔ is an integer from 2 to 4. ｔ is an integer from 1 to 10. ｔ is 1 or 2. ｔ＋ is a monovalent radiation-sensitive onium cation. ｔ If is 2, then two Q ｔ are the same or different, and two M ｔ＋ are the same or different. ｔ is 2 or more or p ｔ If is 2, there are multiple R ｔ１ and R ｔ２ are each independently the same or different.

[0133] In the above formula (II-2u), L ｕ is a divalent linking group. ｕ is a single bond or a divalent linking group. ｕ１ is a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ｕ２ is a group having 6 to 20 carbon atoms (m ｕ +p ｕ +1)-valent aromatic hydrocarbon group. ｕ１ and R ｕ２ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ｕ is an integer from 0 to 4. ｕ is an integer from 1 to 10. ｕ is 1 or 2. ｕ＋ is a monovalent radiation-sensitive onium cation. ｕ If is 2, then two Q ｕ are the same or different, and two M ｕ＋ are the same or different. ｕ is 2 or more or p ｕ If is 2, there are multiple R ｕ１ and R ｕ２ are each independently the same or different, provided that m ｕ If is 0, Ar ｕ１ contains an aromatic ring having two or more iodo groups, or contains two or more aromatic rings having one iodo group. ｕ If is 1, Arｕ１ contains an aromatic ring bearing one or more iodo groups.

[0134] Q ｔ , L ｕ and Q ｕ Examples of the divalent linking group represented by the formula (I) include a carbonyl group, an ether group, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, and a divalent hydrocarbon group. A carbon atom constituting the divalent hydrocarbon group may be substituted with a carbonyl group or an ether group. ｕ As Q, a carbonyloxy group is preferred. ｔ and Q ｕ is preferably a group in which one or more carbon atoms selected from the group consisting of a carbonyl group, an ether group, a carbonyloxy group, and a divalent hydrocarbon group having 1 to 20 carbon atoms are combined, and a carbon atom constituting the divalent hydrocarbon group having 1 to 20 carbon atoms may be substituted with a carbonyl group or an ether group.

[0135] In addition, m ｕ If is 0, Ar ｕ１ contains an aromatic ring having two or more iodo groups, or contains two or more aromatic rings having one iodo group. ｕ If is 1, Ar ｕ１ contains an aromatic ring having one or more iodo groups. Examples of such an aromatic ring having an iodo group include an iodophenylene group, an iodotolylene group, an iodonaphthylene group, a diiodophenylene group, and a diiodonaphthylene group.

[0136] Ar ｔ (m ｔ +p ｔ +1)-valent aromatic hydrocarbon group, Ar ｕ１ and Ar ｕ２ (m ｕ +p ｕ The aromatic hydrocarbon ring having 6 to 20 carbon atoms that gives the aromatic hydrocarbon group having a valence of +1 is, for example, the above Ar ｓ (m ｓ +p ｓExamples of the aromatic hydrocarbon ring having 6 to 20 carbon atoms that provides a divalent aromatic hydrocarbon group include those listed above. Among these, a benzene ring and a naphthalene ring are preferred. ｔ , Ar ｕ１ and Ar ｕ２ may have a substituent, and examples of such a substituent include a halogen atom, an alkoxy group, a hydroxy group, a carboxy group, and a nitro group.

[0137] R ｔ１ , R ｔ２ , R ｕ１ and R ｕ２ Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula (R) include a fluorinated alkyl group having 1 to 20 carbon atoms. ｓ１ and R ｓ２ As the alkyl group, a fluorine atom or a fluorinated alkyl group is preferable, a fluorine atom or a perfluoroalkyl group is more preferable, a fluorine atom or a trifluoromethyl group is further preferable, and a fluorine atom is particularly preferable.

[0138] m ｔ is preferably 2 or 3. ｕ As the number, 1 to 3 are preferred, and 2 or 3 is more preferred.

[0139] n ｔ and n ｕ is preferably 1 to 4, and more preferably 1 or 2.

[0140] M ｔ＋ and M ｕ＋ Examples of the radiation-sensitive onium cation include those similar to those described below as the radiation-sensitive onium cation.

[0141] Compound (II-2) is preferably a compound represented by the following formulas (II-2-1) to (II-2-17). Note that the compounds represented by the following formulas (II-2-9) and (II-2-17) do not fall under either of the above formulas (II-2t) and (II-2u).

[0142]

[0143]

[0144]

[0145]

[0146] In the above formulas (II-2-1) to (II-2-8) and (II-2-10), M ｕ＋ has the same meaning as in formula (II-2u). In formulas (II-2-11) to (II-2-16), M ｔ＋ has the same meaning as in formula (II-2t). In formulas (II-2-9) and (II-2-17), M ｙ＋ is a monovalent radiation-sensitive onium cation. ｔ＋ are independent of each other.

[0147] The use of compound (II-2) as the structural unit (II) is preferred because it may improve the CDU. Although the reason for this is unclear, the inventors believe that it may be related to the glass transition temperature of polymer (A).

[0148] The lower limit of the content of the structural unit (II) in the polymer [A] is preferably 1 mol%, more preferably 3 mol%, even more preferably 5 mol%, and particularly preferably 7 mol%, based on all structural units constituting the polymer [A]. The upper limit of this content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 20 mol%. By setting the content of the structural unit (II) within the above range, the sensitivity and CDU of the radiation-sensitive composition can be further improved.

[0149] [Structural Unit (III)] The polymer (A) preferably further has a side chain containing a phenolic hydroxyl group. The side chain is preferably a structural unit containing a phenolic hydroxyl group (third structural unit, also referred to as structural unit (III)).

[0150] In the case of KrF exposure, EUV exposure, or electron beam exposure, the sensitivity of the radiation-sensitive composition can be further increased when the polymer [A] contains the structural unit (III). Therefore, when the polymer [A] contains the structural unit (III), the radiation-sensitive composition can be suitably used as a radiation-sensitive composition for KrF exposure, EUV exposure, or electron beam exposure.

[0151] Examples of the structural unit (III) include a structural unit represented by the following formula (III-1) (hereinafter referred to as structural unit (III-1)).

[0152]

[0153] In the above formula (III-1), R Ｐ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｐ is a single bond, —COO—, —O—, or —CONH—. Ｐ represents a group in which (p+1) hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring structure having 6 to 30 ring members, where p is an integer of 1 to 3.

[0154] R Ｐ From the viewpoint of copolymerizability of the monomer that gives the structural unit (III-1), a hydrogen atom or a methyl group is preferred.

[0155] L Ｐ is preferably a single bond or —COO—, and more preferably a single bond. Ｐ When is a single bond, the CDU of the radiation-sensitive composition can be further improved.

[0156] Ar Ｐ Examples of aromatic hydrocarbon ring structures having 6 to 30 ring members that give the following formula (1-1) include Ar １ Among the aromatic ring structures having 5 to 30 ring members that give the above formula, examples include the same as those exemplified as the aromatic hydrocarbon ring structure having 6 to 30 ring members. Among these, a benzene structure or a naphthalene structure is preferred, and a benzene structure is more preferred.

[0157] Some or all of the hydrogen atoms in the aromatic hydrocarbon ring structure may be substituted with a substituent. １ Examples of the substituent that the above ring structure that gives the following formula may have include the same groups as those exemplified above.

[0158] p is preferably 1 or 2. When p is 1, the CDU of the radiation-sensitive composition can be further improved. When p is 2, the sensitivity of the radiation-sensitive composition can be further improved.

[0159] Also, p is 1 and L Ｐ When is —COO—, the hydroxy group is Ar Ｐ Among the carbon atoms constituting L Ｐ It is preferred that p is 2 or more and L is bonded to a carbon atom adjacent to the carbon atom bonded to L. Ｐ When Ar is —COO—, at least one hydroxy group is Ｐ Among the carbon atoms constituting L Ｐ In other words, at least one hydroxy group and L Ｐ is Ar Ｐ In this case, the occurrence of defects in a resist pattern formed from the radiation-sensitive composition can be suppressed.

[0160] Examples of the structural unit (III-1) include structural units represented by the following formulae (III-1-1) to (III-1-20) (hereinafter also referred to as "structural units (III-1-1) to (III-1-20)").

[0161]

[0162] In the above formulas (III-1-1) to (III-1-20), R Ｐ has the same meaning as the above formula (III-1).

[0163] When the polymer [A] has the structural unit (III), the lower limit of the content of the structural unit (III) in the polymer [A] is preferably 10 mol%, more preferably 15 mol%, even more preferably 20 mol%, and particularly preferably 25 mol%, based on all structural units constituting the polymer [A]. The upper limit of the content is preferably 60 mol%, more preferably 50 mol%, even more preferably 45 mol%, and particularly preferably 40 mol%.

[0164] Examples of monomers that provide the structural unit (III) 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 [A] having the structural unit (III).

[0165] [Other structural units] The other structural units are structural units other than the above structural units (I) to (III). Examples of the other structural units include 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)").

[0166] (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. When the polymer (A) further contains the structural unit (IV), adhesion to the substrate can be improved.

[0167] Examples of the structural unit (IV) include structural units represented by the following formula:

[0168]

[0169]

[0170]

[0171]

[0172] In the above formula, R Ｌ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0173] The structural unit (IV) is preferably a structural unit containing a lactone structure.

[0174] When the polymer [A] 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 all structural units constituting the polymer [A].The upper limit of the content is preferably 35 mol %, more preferably 25 mol %.

[0175] (Structural Unit (V)) The structural unit (V) is a structural unit containing an alcoholic hydroxyl group (excluding those corresponding to the structural unit (IV)). When the polymer (A) further contains the structural unit (V), the solubility in a developer can be more appropriately adjusted.

[0176] Examples of the structural unit (V) include structural units represented by the following formula:

[0177]

[0178] In the above formula, R Ｌ２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0179] When the polymer [A] contains the structural unit (V), the lower limit of the content of the structural unit (V) is preferably 5 mol %, more preferably 10 mol %, based on all structural units constituting the polymer [A]. The upper limit of the content is preferably 35 mol %, more preferably 25 mol %.

[0180] <[B] Acid Generator> The [B] acid generator is a substance that generates an acid upon exposure (excluding the [A] polymer), and preferably has a molecular weight of 2,500 or less, particularly 1,500 or less. Examples of radiation used for exposure include those exemplified as radiation used in the exposure step of the resist pattern formation method described below. The acid generated upon exposure dissociates acid-dissociable groups contained in the [A] polymer or the like, generating carboxyl groups or phenolic hydroxyl groups, which results in a difference in the solubility of the resist film in a developer between exposed and unexposed areas, thereby forming a resist pattern. It is also possible to use a [P] polymer different from the [A] polymer as the [B] acid generator. The radiation-sensitive composition of the present invention contains a radiation-sensitive onium cation structure in the [A] polymer, but the [P] polymer does not contain the radiation-sensitive onium cation structure.

[0181] Examples of the acid generated from the acid generator (B) include sulfonic acid, carboxylic acid, and imide acid.

[0182] Examples of the acid generator (B) include an onium salt compound, an N-sulfonyloxyimide compound, a sulfonimide compound, a halogen-containing compound, and a diazoketone compound.

[0183] Examples of the onium salt compound include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts.

[0184] Specific examples of the acid generator (B) include the compounds described in paragraphs

[0080] to

[0113] of JP-A No. 2009-134088.

[0185] The acid generator (B) is preferably an onium salt compound, and more preferably an onium salt compound comprising a radiation-sensitive onium cation and an organic acid anion.

[0186] Examples of the radiation-sensitive onium cation include monovalent cations represented by the following formulae (r-a) to (r-b) (hereinafter also referred to as "cations (r-a) to (r-b)").

[0187]

[0188] In the above formula (r-a), b1 is an integer of 0 to 4. When b1 is 1, R Ｂ１ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. Ｂ１ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or are parts of a ring structure having 4 to 20 ring members formed by combining these groups together with the carbon chain to which they are bonded. b2 is an integer of 0 to 4. When b2 is 1, R Ｂ２ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. Ｂ２ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or are parts of a ring structure having 4 to 20 ring members formed by combining these groups together with the carbon chain to which they are bonded. Ｂ３ and R Ｂ４ are each independently a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or are combined with each other to form a single bond. b3 is an integer of 0 to 11. When b3 is 1, R Ｂ５ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. Ｂ５ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or are parts of a ring structure having 4 to 20 ring members formed by combining these groups together with the carbon chain to which they are bonded. ｂ１ is an integer from 0 to 3.

[0189] In the above formula (r-b), b4 is an integer of 0 to 5. When b4 is 1, R Ｂ６ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. Ｂ６are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or are parts of a ring structure having 4 to 20 ring members formed by combining these groups together with the carbon chain to which they are bonded. b5 is an integer of 0 to 5. When b5 is 1, R Ｂ７ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. Ｂ７ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or are parts of a ring structure having 4 to 20 ring members formed by combining these groups together with the carbon chain to which they are bonded.

[0190] "Organic group" refers to a group containing at least one carbon atom.

[0191] R Ｂ１ , R Ｂ２ , R Ｂ３ , R Ｂ４ , R Ｂ５ and R Ｂ６ Examples of the monovalent organic group having 1 to 20 carbon atoms represented by 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 atoms 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.

[0192] Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include R Ｂ , R Ｃ , R Ｕ , R Ｖ or R Ｗ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include the same groups as those exemplified above as the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the following formula:

[0193] 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. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0194] Examples of divalent heteroatom-containing groups include -O-, -CO-, -S-, -CS-, -NR'-, and groups combining two or more of these (e.g., -COO-, -CONR'-, etc.), where R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0195] R Ｂ１ , R Ｂ２ , R Ｂ５ , R Ｂ６ and R Ｂ７ is preferably a halogen atom or a group in which some or all of the hydrogen atoms in a monovalent hydrocarbon group having 1 to 20 carbon atoms have been substituted with a monovalent halogen atom. In this case, the halogen atom is preferably a fluorine atom or an iodine atom. In this case, a good balance between the sensitivity and CDU of the radiation-sensitive composition can be achieved.

[0196] R Ｂ３ and R Ｂ４ is preferably a hydrogen atom or a single bond formed by combining these atoms together.

[0197] b1, b2 and b3 are preferably 0 to 3. ｂ１ is preferably 0 or 1.

[0198] b4 and b5 are preferably 0 or 1.

[0199] Among the above cations (r-a) to (r-b), a monovalent radiation-sensitive onium cation (hereinafter also referred to as "cation (P)") containing an aromatic ring structure in which at least one hydrogen atom is substituted with at least one group selected from the group consisting of a fluorine atom, a fluorine atom-containing group, and an iodine atom is preferred. The cation (r-a) corresponding to cation (P) is a cation in which b1 is an integer of 1 to 3 and at least one R Ｂ１is at least one group selected from the group consisting of a fluorine atom, a fluorine atom-containing group, and an iodine atom. Ｂ１ is a fluorine atom or an iodine atom, and at least one R Ｂ２ is a fluorine atom or an iodine atom. In addition, as the cation (r-b) corresponding to the cation (P), b4 is an integer of 1 to 5, and at least one R Ｂ６ is a fluorine atom or an iodine atom. Among them, b4 and b5 are each independently an integer of 1 to 5, and at least one R Ｂ６ is a fluorine atom or an iodine atom, and at least one R Ｂ７ is preferably a cation in which the cation is a fluorine atom or an iodine atom.

[0200] Examples of the organic acid anion include a sulfonate anion, a carboxylate anion, and an imidate anion.

[0201] Among these, the acid generator [B] is preferably an onium salt compound (hereinafter also referred to as “compound [Z]”) having the above cation (P) and a monovalent organic acid anion (hereinafter also referred to as “anion (Q)”).

[0202] Examples of the cation (P) include cations represented by the following formulas (2-1-1) to (2-1-12) (hereinafter also referred to as "cations (P-1-1) to (P-1-12)"). Examples of radiation-sensitive onium cations other than the cation (P) include triphenylsulfonium cation and diphenyliodonium cation.

[0203]

[0204] [Anion (Q)] The anion (Q) is a monovalent organic acid anion. The anion (Q) contains a monovalent anionic group. Examples of the monovalent anionic group include a sulfonic acid anionic group, a carboxylic acid anionic group, and an imidic acid anionic group. Among these, a sulfonic acid anionic group or a carboxylic acid anionic group is preferred.

[0205] Among the anions (Q), anions having a sulfonate anion group as a monovalent anion group (hereinafter also referred to as "anion (Q-1)") will be described below.

[0206] (Anion (Q-1)) The anion moiety (Q-1) is not particularly limited as long as it is a sulfonate anion used as an anion in an onium salt-type radiation-sensitive acid generator, and examples thereof include sulfonate anions represented by the following formula (4-1):

[0207]

[0208] In the above formula (4-1), R ｐ１ is a monovalent group containing a ring structure having 5 or more ring members. ｐ２ is a divalent linking group. ｐ３ and R ｐ４ 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. ｐ５ and R ｐ６ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ｐ１ is an integer from 0 to 10. ｐ２ is an integer from 0 to 10. ｐ３ is an integer from 0 to 10. ｐ１ +n ｐ２ +n ｐ３ is 1 or more and 30 or less. ｐ１ If there are two or more R ｐ２ are the same or different. ｐ２ If there are two or more R ｐ３ are the same or different, and multiple R ｐ４ are the same or different. ｐ３ If there are two or more R ｐ５ are the same or different, and multiple R ｐ６ are the same or different from each other.

[0209] Examples of ring structures having 5 or more ring members include aliphatic hydrocarbon ring structures having 5 or more ring members, aliphatic heterocyclic structures having 5 or more ring members, aromatic hydrocarbon ring structures having 6 or more ring members, aromatic heterocyclic structures having 5 or more ring members, and combinations thereof.

[0210] Examples of aliphatic hydrocarbon ring 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 five-membered ring are fused. Among these, the steroid structure is preferred.

[0211] 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.

[0212] Examples of aromatic hydrocarbon ring structures having 6 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; a 9,10-ethanoanthracene structure; and a triptycene structure. Of these, a benzene structure and a 9,10-ethanoanthracene structure are preferred.

[0213] 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.

[0214] 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, such as a halogen atom such as a fluorine atom or an iodine 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).

[0215] 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.

[0216] R ｐ１ As the aryl group, a monovalent group containing an aliphatic hydrocarbon ring structure having 5 or more ring members, a monovalent group containing an aliphatic heterocyclic structure having 5 or more ring members, or a monovalent group containing an aromatic hydrocarbon ring structure having 6 or more ring members is preferred. Among these, a monovalent group containing an aromatic hydrocarbon ring structure having 6 or more ring members and having 1 to 4 iodine atoms as a substituent is preferred.

[0217] R ｐ２ Examples of the divalent linking group represented by the formula (I) include a carbonyl group, an ether group, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, a divalent hydrocarbon group, or a combination thereof. A carbon atom constituting the divalent hydrocarbon group may be substituted with a carbonyl group or an ether group.

[0218] R ｐ３ and R ｐ４ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R include an alkyl group having 1 to 20 carbon atoms. ｐ３ and R ｐ４ Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula (R) include a fluorinated alkyl group having 1 to 20 carbon atoms.ｐ３ and R ｐ４ is preferably a hydrogen atom, a fluorine atom or a fluorinated alkyl group, more preferably a hydrogen atom, a fluorine atom or a perfluoroalkyl group, and even more preferably a hydrogen atom, a fluorine atom or a trifluoromethyl group.

[0219] R ｐ５ and R ｐ６ Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula (R) include a fluorinated alkyl group having 1 to 20 carbon atoms. ｐ５ and R ｐ６ As the alkyl group, a fluorine atom or a fluorinated alkyl group is preferable, a fluorine atom or a perfluoroalkyl group is more preferable, a fluorine atom or a trifluoromethyl group is further preferable, and a fluorine atom is particularly preferable.

[0220] n ｐ１ is preferably 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0221] n ｐ２ is preferably 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0222] n ｐ３ The lower limit of n is preferably 1, and more preferably 2. ｐ３ By making n equal to or greater than 1, the strength of the acid can be increased. ｐ３ The upper limit of is preferably 4, more preferably 3, and even more preferably 2.

[0223] n ｐ１ +n ｐ２ +n ｐ３ The lower limit of n is preferably 2, more preferably 4. ｐ１ +n ｐ２ +n ｐ３ The upper limit of is preferably 20, more preferably 10.

[0224] The anion (Q-1) is preferably a sulfonate anion represented by the following formulas (4-1-1) to (4-1-16).

[0225]

[0226]

[0227] Of the anions (Q), anions having a carboxylate anion group as a monovalent anion group can have an anion structure in which the sulfonate anion in the above formula (4-1) is replaced with a carboxylate anion.

[0228] The lower limit of the content of the acid generator (B) in the radiation-sensitive composition is preferably 1 part by mass, more preferably 5 parts by mass, and even more preferably 10 parts by mass, relative to 100 parts by mass of the polymer (A).The upper limit of the content is preferably 50 parts by mass, more preferably 40 parts by mass, and even more preferably 30 parts by mass.

[0229] <[C] Acid Diffusion Controller> The [C] acid diffusion controller controls the diffusion phenomenon in the resist film of acid generated from the [A] polymer or the [B] acid generator upon exposure, thereby suppressing undesirable chemical reactions in unexposed regions. Examples of the [C] acid diffusion controller include compounds having a monovalent radiation-sensitive onium cation and a monovalent organic acid anion (hereinafter also referred to as a "photodegradable base") (excluding the [A] polymer). Since the photodegradable base generates acid upon exposure, it can also be called an acid generator in a broad sense. However, under conditions where the acid generated from the [A] polymer or the [B] acid generator upon exposure dissociates the acid-dissociable group in the [A] polymer, the photodegradable base does not dissociate the acid-dissociable group upon exposure. The molecular weight of the photodegradable base is preferably 2,500 or less, more preferably 1,500 or less. It should be noted that the [C] acid diffusion controller can also be a polymer having a repeating unit having the above-mentioned function.

[0230] Examples of the monovalent radiation-sensitive onium cation in the photodegradable base include the same cations as those exemplified as the cations in the acid generator (B). Among these, a monovalent radiation-sensitive onium cation (cation (P)) containing an aromatic ring structure in which at least one hydrogen atom is substituted with at least one group selected from the group consisting of a fluorine atom, a fluorine-containing group, and an iodine atom is preferred.

[0231] The monovalent organic acid anion in the photodegradable base contains a monovalent anionic group. Examples of the monovalent anionic group include a carboxylate anionic group and an imidate anionic group. Among these, a carboxylate anionic group is preferred.

[0232] Among the anions (Q), anions having a carboxylate anion group as a monovalent anion group (hereinafter also referred to as "anion (Q-2)") will be described below.

[0233] The anion (Q-2) is not particularly limited as long as it is an anion usable as an anion in a photodegradable base that is photosensitive upon exposure to generate a weak acid. Among these, a carboxylate anion containing an aromatic ring structure in which one to three hydrogen atoms are substituted with iodo groups is preferred, and a carboxylate anion containing an aromatic ring structure in which two to three hydrogen atoms are substituted with iodo groups is more preferred.

[0234] The anion moiety (Q-2) is preferably a carboxylate anion represented by the following formulas (4-2-1) to (4-2-12).

[0235]

[0236]

[0237] As the photodegradable base, for example, a compound in which a monovalent radiation-sensitive onium cation and the above-mentioned anion moiety (Q-2) are appropriately combined can be used.

[0238] As the acid diffusion controller (C), a nitrogen atom-containing compound can also be used as a compound other than the photodegradable base. 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 N-t-pentyloxycarbonyl-4-hydroxypiperidine.

[0239] When the radiation-sensitive composition contains the acid diffusion controller (C), the lower limit of the content of the acid diffusion controller (C) in the radiation-sensitive composition is preferably 1 part by mass, more preferably 3 parts by mass, and even more preferably 5 parts by mass, relative to 100 parts by mass of the polymer (A) contained in the radiation-sensitive composition, and the upper limit of the content is preferably 30 parts by mass, more preferably 20 parts by mass, and even more preferably 15 parts by mass.

[0240] The lower limit of the content of the acid diffusion controller (C) in the radiation-sensitive composition is preferably 1 mol %, more preferably 5 mol %, and even more preferably 10 mol %, relative to 100 mol % of the acid generator (B).The upper limit of the content is preferably 100 mol %, more preferably 50 mol %, and even more preferably 30 mol %.

[0241] The lower limit of the content of the acid diffusion controller (C) in the radiation-sensitive composition is preferably 1 part by mass, more preferably 2 parts by mass, and even more preferably 5 parts by mass, relative to 100 parts by mass of the total of the polymer (A) and the acid generator (B). The upper limit of the content is preferably 50 parts by mass, more preferably 40 parts by mass, and even more preferably 30 parts by mass.

[0242] <[D] Organic Solvent> The radiation-sensitive composition 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 [A], the acid generator [B], the acid diffusion controller [C], the polymer [F], and other optional components that may be contained as needed.

[0243] Examples of the organic solvent (D) include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, hydrocarbon-based solvents, etc. The radiation-sensitive composition may contain one or more organic solvents (D).

[0244] 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.

[0245] 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.

[0246] 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; and 2,4-pentanedione, acetonylacetone, and acetophenone.

[0247] 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.

[0248] Examples of ester-based solvents include monocarboxylic acid ester-based solvents such as n-butyl acetate and ethyl lactate; lactone-based solvents such as γ-butyrolactone and valerolactone; polyhydric alcohol carboxylate-based solvents such as propylene glycol acetate; polyhydric alcohol partial ether carboxylate-based solvents such as propylene glycol monomethyl ether acetate; polycarboxylic acid diester-based solvents such as diethyl oxalate; and carbonate-based solvents such as dimethyl carbonate and diethyl carbonate.

[0249] 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.

[0250] The organic solvent (D) is preferably an alcohol solvent, an ester solvent, or a combination thereof, more preferably a polyhydric alcohol partial ether solvent having 3 to 19 carbon atoms, a polyhydric alcohol partial ether carboxylate solvent, or a combination thereof, and even more preferably propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, or a combination thereof.

[0251] When the radiation-sensitive composition contains the organic solvent (D), the lower limit of the content of the organic solvent (D) is preferably 50 mass %, more preferably 60 mass %, still more preferably 70 mass %, and particularly preferably 80 mass %, based on all components contained in the radiation-sensitive composition, and the upper limit of the content is preferably 99.9 mass %, preferably 99.5 mass %, and more preferably 99.0 mass %.

[0252] <Polymer [F]> The polymer [F] is a polymer different from the polymer [A] and has a higher fluorine atom content than the polymer [A]. Typically, polymers that are more hydrophobic than the base polymer tend to be unevenly distributed in the surface layer of the resist film. The polymer [F] has a higher fluorine atom content than the polymer [A], and due to this hydrophobicity-induced property, the polymer [F] tends to be unevenly distributed in the surface layer of the resist film. As a result, when the radiation-sensitive composition contains the polymer [F], it is expected that the cross-sectional shape of the formed resist pattern will be excellent. Furthermore, when the radiation-sensitive composition contains the polymer [F], the cross-sectional shape of the resist pattern can be further improved.

[0253] The form of fluorine atoms contained in the polymer [F] is not particularly limited, and they may be bonded to either the main chain or the side chain of the polymer [F]. Regarding the form of fluorine atoms contained in the polymer [F], the polymer [F] preferably has a structural unit containing a fluorine atom (hereinafter also referred to as "structural unit (F)"). The polymer [F] may further have a structural unit other than the structural unit (F). The polymer [F] may have one or two or more types of each structural unit.

[0254] When the radiation-sensitive composition contains the polymer [F], the lower limit of the amount of the polymer [F] relative to 100 parts by mass of the polymer [A] is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, and the upper limit of the amount is preferably 10 parts by mass, more preferably 5 parts by mass.

[0255] <Other Optional Components> Examples of other optional components include surfactants, etc. The radiation-sensitive composition may contain one or more other optional components.

[0256] <Method of Forming a Resist Pattern> The method of forming a resist pattern includes a step of applying a radiation-sensitive composition directly or indirectly to a substrate (hereinafter also referred to as a "coating step"), a step of exposing the resist film formed in 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").

[0257] In the coating step, the radiation-sensitive composition is the radiation-sensitive composition described above. Therefore, according to the method for forming a resist pattern, a resist pattern with good sensitivity and excellent CDU can be formed.

[0258] Each step of the resist pattern forming method will be described below.

[0259] [Coating Step] In this step, the radiation-sensitive composition is coated directly or indirectly onto a substrate, thereby forming a resist film directly or indirectly on the substrate.

[0260] In this step, the radiation-sensitive composition described above is used as the radiation-sensitive composition.

[0261] Examples of the substrate include conventionally known substrates such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Examples of indirectly applying the radiation-sensitive composition to a substrate include applying the radiation-sensitive composition to 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.

[0262] Examples of coating methods include spin coating, casting coating, and roll coating. After coating, pre-baking (hereinafter also referred to as "PB") may be performed, if necessary, 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 resist film to be formed is preferably 10 nm, more preferably 20 nm. The upper limit of the average thickness is preferably 1,000 nm, more preferably 500 nm.

[0263] [Exposure Step] In this step, the resist film formed in the coating step is exposed to radiation. 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 radiation 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.

[0264] After the exposure, post-exposure baking (hereinafter also referred to as "PEB") is preferably performed to promote dissociation of the acid-dissociable group from the structural unit (I) in the exposed portion of the resist film due to the action of the acid generated from the polymer [A] or the like upon exposure. This PEB can increase the difference in solubility in a developer between the exposed portion and the unexposed portion. The lower limit of the PEB temperature is preferably 50°C, more preferably 80°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.

[0265] [Development Step] 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.

[0266] 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 % aqueous TMAH solution is more preferred.

[0267] 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, and solutions containing any of the above organic solvents. Examples of the organic solvents include the solvents exemplified as the organic solvent (D) in the radiation-sensitive composition described above.

[0268] Examples of the developing method include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of piling up the developer on the surface of the substrate by surface tension and leaving it to stand for a certain period of time (puddle method), a method of spraying the developer onto the surface of the substrate (spray method), and a method of continuously discharging the developer while scanning a developer discharging nozzle at a constant speed onto a substrate that is rotating at a constant speed (dynamic dispense method).

[0269] Examples of resist patterns formed by the resist pattern forming method include line and space patterns and contact hole patterns.

[0270] <Polymer> The polymer of the present invention has a side chain containing an acid-dissociable group, and a side chain containing two or more iodine groups and one or more radiation-sensitive onium cation structures. The side chain containing the acid-dissociable group is preferably contained in a first structural unit containing a partial structure in which a hydrogen atom of a carboxy group or a phenolic hydroxyl group is substituted with an acid-dissociable group. The side chain containing two or more iodine groups and one or more radiation-sensitive onium cation structures is preferably contained in a second structural unit (excluding those corresponding to the first structural unit) containing two or more iodine groups and one or more radiation-sensitive onium cation structures. The structure of this polymer is the same as that of polymer [A] contained in the radiation-sensitive composition, and the description thereof is incorporated herein by reference.

[0271] 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.

[0272] [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 in the above section [Method for measuring Mw and Mn]. The polydispersity (Mw / Mn) of the polymer was calculated from the measurement results of Mw and Mn.

[0273] <Synthesis of Polymer [A]> Polymers (A-1) to (A-40) and (CA-1) to (CA-3) were synthesized as polymer [A] by known methods. For the synthesis of polymer [A], compounds represented by the following formulae (M-1) to (M-16) and monomers (pm-101) to (pm-110), (pm-201) to (pm-217), (pm-301) and (pm-401) shown in Table 1 were used. In the following synthesis examples, unless otherwise specified, "parts by mass" means a value when the total mass of the monomers used is taken as 100 parts by mass, and "mol %" means a value when the total number of moles of the monomers used is taken as 100 mol %. Note that pm-213 is a compound represented by formula (II-2-13) in which two M ｔ＋ are both cations represented by ca-1. pm-216 is a compound represented by formula (II-2-16), ｔ＋are all cations represented by ca-1. The monomers other than pm-213 and pm-216 are monomers consisting of 1 mol of cation and 1 mol of anion.

[0274]

[0275]

[0276]

[0277] The types and proportions of monomers that provide each structural unit of the polymer [A] obtained in Synthesis Examples 1 to 43, as well as Mw and Mw / Mn, are shown in Table 2. In Table 2, "-" indicates that the corresponding monomer was not used.

[0278]

[0279] <Preparation of Radiation-Sensitive Composition> The acid generator [B], the acid diffusion controller [C], the organic solvent [D], and the polymer [F] used in the preparation of the radiation-sensitive composition are shown below. In the following examples and comparative examples, unless otherwise specified, "parts by mass" means a value when the mass of the polymer [A] used is taken as 100 parts by mass, and "mol %" means a value when the number of moles of the acid generator [B] used is taken as 100 mol %.

[0280] [[B] Acid Generator] As the acid generator [B], compounds represented by the following formulas (B-1) to (B-5) (hereinafter also referred to as "acid generators (B-1) to (B-5)") were used.

[0281]

[0282] [[C] Acid Diffusion Controller] As the acid diffusion controller [C], compounds represented by the following formulas (C-1) to (C-4) (hereinafter also referred to as "acid diffusion controllers (C-1) to (C-4)") were used.

[0283]

[0284] [[D] Organic Solvent] The following organic solvents were used as the organic solvent [D]: (D-1): Propylene glycol monomethyl ether acetate (D-2): Propylene glycol monomethyl ether (D-3): Cyclohexanone (D-4): γ-butyrolactone (D-5): Ethyl lactate (D-6): Diacetone alcohol

[0285] [Polymer [F]] The polymer [F] used was a polymer represented by the following formula (F-1), having Mw of 8,900 and Mw / Mn of 2.0.

[0286]

[0287] [Example 1] Preparation of Radiation-Sensitive Composition (R-1) 100 parts by mass of (A-1) as the [A] polymer, 5 parts by mass of (C-1) as the [C] acid diffusion controller, and 5,000 parts by mass of (D-1) and 2,000 parts by mass of (D-2) as the [D] organic solvent were mixed. The resulting mixture was filtered through a membrane filter with a pore size of 0.20 μm to prepare a radiation-sensitive composition (R-1).

[0288] [Examples 2 to 50 and Comparative Examples 1 to 3] Preparation of radiation-sensitive compositions (R-2) to (R-50) and (CR-1) to (CR-3) Radiation-sensitive compositions (R-2) to (R-50) and (CR-1) to (CR-3) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Table 3 below were used.

[0289] <Formation of Resist Pattern> Each of the radiation-sensitive compositions prepared above was applied to the surface of a 12-inch silicon wafer on which an underlayer film (Brewer Science's "AL412") with an average thickness of 20 nm had been formed, using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"). Pre-baking (PB) was performed at 130°C for 60 seconds, followed by cooling at 23°C for 30 seconds to form a resist film with an average thickness of 50 nm. Next, this resist film was irradiated with EUV light using an EUV exposure machine (ASML's "NXE3400", NA = 0.33, σ 0.9 / 0.6, quadrupole illumination conditions). After irradiation, the resist film was subjected to post-exposure baking (PEB) at 130°C for 60 seconds. Next, the resist was developed using a 2.38% by mass aqueous solution of TMAH at 23° C. for 30 seconds to form a positive contact hole pattern (diameter 25 nm, pitch 50 nm).

[0290] <Evaluation> The sensitivity and CDU of each resist pattern formed above were evaluated according to the following methods. A scanning electron microscope (CG-4100, manufactured by Hitachi High-Tech Corporation) was used to measure the length of the resist pattern. The evaluation results are shown in Table 3 below.

[0291] [Sensitivity] In forming the resist pattern, the exposure dose for forming a contact hole pattern with a diameter of 25 nm is defined as the optimum exposure dose, and this optimum exposure dose is expressed as Eop (mJ / cm ２ ) The smaller the value of sensitivity, the higher the sensitivity and the better the result. With the sensitivity of Comparative Example 1 as the standard, cases where sensitivity was increased by more than 6% are marked as "A", cases where sensitivity was increased by more than 2% but not more than 6% are marked as "B", cases where sensitivity was increased by more than 0% but not more than 2% are marked as "C", and cases where sensitivity was not increased are marked as "D". The sensitivity of Comparative Example 1 is marked as "-".

[0292] [CDU] The resist pattern was observed from above using the scanning electron microscope, and the diameters of a total of 800 contact hole patterns were measured at random locations. The 3 sigma value was calculated from the distribution of the measured values, and this was designated as CDU (unit: nm). The smaller the CDU value, the smaller the long-period hole diameter variation, indicating better results. Using the CDU of Comparative Example 1 as the standard, an improvement of more than 6% is designated as "A," an improvement of more than 2% to 6% is designated as "B," an improvement of more than 0% to 2% is designated as "C," and no improvement is designated as "D," as shown in Table 3. The CDU of Comparative Example 1 is designated as "-."

[0293]

[0294] The radiation-sensitive compositions of the Examples all had superior sensitivity and CDU to the radiation-sensitive compositions of the Comparative Examples. [B] When acid generator (B-1) or (B-3) was used as the acid generator, which contained an onium salt compound composed of a radiation-sensitive onium cation and an organic acid anion, and the radiation-sensitive onium cation contained an aromatic ring substituted with a fluorine atom (Examples 42 and 44), the sensitivity was even superior to that when acid generator (B-1) or (B-3) was not used (Example 28). [B] When acid generator (B-2) was used as the acid generator, which contained an onium salt compound composed of a radiation-sensitive onium cation and an organic acid anion, and the organic acid anion contained an aromatic hydrocarbon ring structure having 6 or more ring members and 1 to 4 iodine atoms as a substituent (Example 43), the CDU was even superior to that when acid generator (B-2) was not used (Example 28).

[0295] Furthermore, when the acid diffusion controller (C-3) [C] was used as the acid diffusion controller, the acid diffusion controller (C-3) was a compound having a monovalent radiation-sensitive onium cation and a monovalent organic acid anion, and the organic acid anion contained a carboxylate anion having an aromatic ring structure in which one to three hydrogen atoms were substituted with iodo groups (Example 46), the CDU was even better than when the acid diffusion controller (C-3) was not used (Example 28).

Claims

1. Polymer having a side chain containing an acid-dissociable group and a side chain containing two or more iodine groups and one or more radiation-sensitive onium cation structures A radiation-sensitive composition comprising:

2. The side chain containing the acid-dissociable group is contained in a first structural unit containing a partial structure in which a hydrogen atom of a carboxy group or a phenolic hydroxyl group is substituted with an acid-dissociable group, and the side chain containing two or more iodine groups and one or more radiation-sensitive onium cation structures is contained in a second structural unit (excluding those corresponding to the first structural unit) containing two or more iodine groups and one or more radiation-sensitive onium cation structures. The radiation-sensitive composition according to claim 1 , wherein

3. 3. The radiation-sensitive composition according to claim 2, wherein the second structural unit is derived from a (meth)acrylic acid ester compound containing two or more iodo groups and one or more radiation-sensitive onium cation structures, or a vinyl compound containing two or more iodo groups and one or more radiation-sensitive onium cation structures.

4. 4. The radiation-sensitive composition according to claim 3, wherein the (meth)acrylic acid ester compound is a monomer that is a salt containing a sulfonate anion having a (meth)acryloyloxy group and two or more iodine groups, and a radiation-sensitive onium cation, and the vinyl compound is a monomer that is a salt containing a sulfonate anion having a vinyl group and two or more iodine groups, and a radiation-sensitive onium cation.

5. 2. The radiation-sensitive composition according to claim 1, wherein the radiation-sensitive onium cation structure comprises a monovalent radiation-sensitive onium cation containing an aromatic ring structure in which at least one hydrogen atom is substituted with a fluorine atom or a fluorine atom-containing group.

6. 2. The radiation-sensitive composition according to claim 1, wherein the acid-dissociable group is represented by the following formula (1-1) or (1-2): 【Chemistry 1】 (In formula (1-1), Ar １ R is a group in which one hydrogen atom has been removed from a substituted or unsubstituted aromatic ring structure having 5 to 30 ring members. １ and R ２ are each independently a substituted or unsubstituted monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or R １ and R ２ and are combined together. １ forms a saturated alicyclic hydrocarbon ring having 3 to 8 carbon atoms together with the carbon atom to which it is bonded. * indicates the bonding site with the etheric oxygen atom of the carboxy group or the oxygen atom of the phenolic hydroxyl group. 【Chemistry 2】 (In formula (1-2), R ｖ１ ~R ｖ３ are each independently a hydrogen atom or a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 10 carbon atoms. s is 1 or 2. * indicates the bonding site with the etheric oxygen atom of the carboxy group or the oxygen atom of the phenolic hydroxyl group.

7. Ar in the above formula (1-1) １ 7. The radiation-sensitive composition according to claim 6, wherein the substituted or unsubstituted aromatic ring structure having 5 to 30 ring members that gives the formula (I) is a substituted or unsubstituted aromatic hydrocarbon ring structure having 6 to 30 ring members.

8. 3. The radiation-sensitive composition according to claim 2, wherein the first structural unit is represented by the following formula (3-1) or (3-2): 【Transformation 3】 In formulas (3-1) and (3-2), Z is an acid-dissociable group. In formula (3-1), R １１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ３１ is a divalent linking group. ３１ is 0 or 1. In formula (3-2), R １２ is a hydrogen atom or a methyl group. １３ is a single bond, an oxygen atom, —COO— or —CONH—. ２ R is a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring structure having 6 to 30 ring members. １４ is a single bond or —CO—.

9. 2. The radiation-sensitive composition according to claim 1, wherein the polymer further has a side chain containing a phenolic hydroxyl group.

10. 2. The radiation-sensitive composition according to claim 1, further comprising at least one selected from the group consisting of a radiation-sensitive acid generator and an acid diffusion controller.

11. a step of directly or indirectly applying the radiation-sensitive composition according to any one of claims 1 to 10 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:

12. A polymer having a side chain containing an acid-labile group, and a side chain containing two or more iodine groups and one or more radiation-sensitive onium cation structures.

13. The side chain containing the acid-dissociable group is contained in a first structural unit containing a partial structure in which a hydrogen atom of a carboxy group or a phenolic hydroxyl group is substituted with an acid-dissociable group, and the side chain containing two or more iodine groups and one or more radiation-sensitive onium cation structures is contained in a second structural unit (excluding those corresponding to the first structural unit) containing two or more iodine groups and one or more radiation-sensitive onium cation structures.

13. The polymer of claim 12, wherein

14. The polymer according to claim 13, wherein the second structural unit is derived from a (meth)acrylic acid ester compound containing two or more iodo groups and one or more radiation-sensitive onium cation structures, or a vinyl compound containing two or more iodo groups and one or more radiation-sensitive onium cation structures.

15. 15. The polymer according to claim 14, wherein the (meth)acrylic acid ester compound is a monomer that is a salt containing a sulfonate anion having a (meth)acryloyloxy group and two or more iodine groups, and a radiation-sensitive onium cation, and the vinyl compound is a monomer that is a salt containing a sulfonate anion having a vinyl group and two or more iodine groups, and a radiation-sensitive onium cation.

16. The polymer according to claim 12 , wherein the radiation-sensitive onium cation structure comprises a monovalent radiation-sensitive onium cation containing an aromatic ring structure in which at least one hydrogen atom is substituted with a fluorine atom or a fluorine atom-containing group.

17. A monomer which is a vinyl compound containing two or more iodo groups and one or more radiation-sensitive onium cation structures.

18. The monomer according to claim 17, which is a monomer which is a salt comprising a sulfonate anion having a vinyl group and two or more iodine groups and a radiation-sensitive onium cation, a monomer which is a salt comprising a sulfonate anion having a vinyl group and one iodine group and a radiation-sensitive onium cation having one iodine group, or a monomer which is a salt comprising a sulfonate anion having a vinyl group and a radiation-sensitive onium cation having two or more iodine groups.

19. The monomer according to claim 17, represented by the following formula (II-2t) or formula (II-2u): 【Chemistry 4】 (In formula (II-2t), Q t represents a single bond or a divalent linking group. Art represents an aromatic hydrocarbon group having 6 to 20 carbon atoms and a valence of (m t +p t +1). R t1 and R t2 each independently represent a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. m t represents an integer of 2 to 4. n t represents an integer of 1 to 10. p t represents 1 or 2. M t+ represents a monovalent radiation-sensitive onium cation. When p t is 2, two Q t s are the same or different, and two M t+ s are the same or different. When n t is 2 or greater or p t is 2, multiple R t1 s and multiple R t2 s are each independently the same or different. In formula (II-2u), L u is a divalent linking group. Q u is a single bond or a divalent linking group. Ar u1 is a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. Ar u2 is a (m u +p u +1)-valent aromatic hydrocarbon group having 6 to 20 carbon atoms. R u1 and R u2 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. mu is an integer of 0 to 4.nu is an integer of 1 to 10.pu is 1 or 2.Mu+ is a monovalent radiation-sensitive onium cation. When pu is 2, two Qu's are the same or different, and two Mu+'s are the same or different. When n u is 2 or more or p u is 2, the multiple R u1 and R u2 present are each independently the same or different. However, when m u is 0, Ar u1 contains an aromatic ring having two or more iodo groups, or two or more aromatic rings having one iodo group. Also, when m u is 1, Ar u1 contains an aromatic ring having one or more iodo groups.

Images