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

Abstract

To provide a radiation-sensitive composition having high sensitivity, excellent in CDU performance, and capable of suppressing occurrence of development defect.SOLUTION: A radiation-sensitive composition that contains a polymer having a partial structure represented by formula (1) and a radiation-sensitive acid generator, satisfies at least one of the requirements 1, 2, and 3. Requirement 1: The partial structure represented by formula (1) contains two or more iodine atoms. Requirement 2: The radiation-sensitive acid generator contains an onium salt having two or more iodine atoms. Requirement 3: The partial structure represented by formula (1) contains iodine atoms, and the radiation-sensitive acid generator contains an onium salt that has iodine atoms. In formula (1), Y1 is a specific bivalent group having an aromatic ring. R1 is a bivalent hydrocarbon group. M+ is a sulfonium cation or an iodonium cation.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In lithography techniques used in the manufacturing processes of various electronic devices such as semiconductor devices and liquid crystal devices, a radiation-sensitive composition is irradiated with far ultraviolet rays (such as an ArF excimer laser), extreme ultraviolet rays (EUV), electron beams, or the like to generate an acid in the exposed area. A chemical reaction involving this acid causes a difference in the dissolution rate in a developer between the exposed and unexposed areas, thereby forming a resist pattern on a substrate.

[0003] As the structures of various electronic devices become finer, there is a demand for even finer resist patterns in lithography processes. Furthermore, in response to the demand for even finer resist patterns, various efforts have been made to improve the resolution and resist pattern shape of radiation-sensitive compositions used in microfabrication by lithography (see, for example, Patent Document 1). Patent Document 1 discloses the use of a polymeric compound containing a repeating unit having a sulfonium salt structure with a fluorine atom at the α-position of sulfonic acid as the base resin of the radiation-sensitive composition. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-116550 Summary of the Invention [Problem to be solved by the invention]

[0005] In photolithography, progress is being made in miniaturizing patterns by using short-wavelength radiation such as ArF excimer lasers, or by using liquid immersion lithography, in which exposure is performed while the space between the lens of the exposure tool and the resist film is filled with a liquid medium. Furthermore, development is also underway for next-generation lithography using even shorter-wavelength radiation such as electron beams, X-rays, and extreme ultraviolet (EUV). In efforts to develop these next-generation technologies, there is a demand for further improvements in radiation sensitivity, CDU (Critical Dimension Uniformity), which is an index of resist pattern quality, and the suppression of development defects.

[0006] The present invention has been made in view of the above-mentioned problems, and a main object of the present invention is to provide a radiation-sensitive composition that has high sensitivity, excellent CDU performance, and is capable of suppressing the occurrence of development defects, and a method of forming a resist pattern using the radiation-sensitive composition. [Means for solving the problem]

[0007] According to one embodiment of the present invention, a compound represented by the following formula (1): [ka] [In formula (1), Y 1 is expressed by the following formula (2-1) or formula (2-2): [ka] (In formula (2-1) and formula (2-2), Ar 1 is a divalent aromatic ring group. 2 is a single bond or a divalent aromatic ring group. 3 is a monovalent aromatic ring group. 1 and X 2 are each independently a divalent linking group. n is 0 or 1. 1 " represents a bond to the carbonyl group in formula (1). "*" represents a bond.) R is a divalent group represented by1 is a divalent hydrocarbon group. + is a sulfonium cation or an iodonium cation. "*" represents a bond.] and a radiation-sensitive acid generator, and satisfies one or more of the following requirements 1, 2, and 3. Requirement 1: The partial structure represented by the above formula (1) has two or more iodine atoms. Requirement 2: The radiation-sensitive acid generator contains an onium salt having two or more iodine atoms. Requirement 3: The partial structure represented by the above formula (1) contains an iodine atom, and the radiation-sensitive acid generator contains an onium salt containing an iodine atom.

[0008] According to another aspect of the present invention, there is provided a method for forming a resist pattern, comprising the steps of forming a resist film on a substrate using the above-described radiation-sensitive composition, exposing the resist film to light, and developing the exposed resist film.

[0009] According to another aspect of the present invention, there is provided a compound represented by the following formula (1): [ka] [In formula (1), Y 1 is expressed by the following formula (2-1): [ka] (In formula (2-1), Ar 1 is a divalent aromatic ring group. 2 is a single bond or a divalent aromatic ring group. 1 is a divalent linking group. n is 0 or 1. 1 " represents a bond to the carbonyl group in formula (1). "*" represents a bond.) R is a divalent group represented by 1 is a divalent hydrocarbon group. + is a sulfonium cation or an iodonium cation. "*" represents a bond.] and the partial structure represented by formula (1) has two or more iodine atoms.

[0010] According to another aspect of the present invention, there is provided a compound represented by the following formula (1): [ka] [In formula (1), Y 1 is expressed by the following formula (2-2): [ka] (In formula (2-2), Ar 3 is a monovalent aromatic ring group. 2 is a divalent linking group. 1 " represents a bond to the carbonyl group in formula (1). "*" represents a bond.) R is a divalent group represented by 1 is a divalent hydrocarbon group. + is a sulfonium cation or an iodonium cation. "*" represents a bond.] There is provided a polymer having a partial structure represented by the following formula:

[0011] According to another aspect of the present invention, there is provided a compound represented by the following formula (3-1): [ka] (In formula (3-1), R 2 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond or * 3 -CO-O-. 3 " is R 2 represents the bond to the carbon atom to which Ar is attached. 1 is a divalent aromatic ring group. 2 is a single bond or a divalent aromatic ring group. 1 is a divalent linking group. n is 0 or 1. R 1 is a divalent hydrocarbon group. +is a sulfonium cation or an iodonium cation, provided that formula (3-1) has two or more iodine atoms.

[0012] According to another aspect of the present invention, there is provided a compound represented by the following formula (3-2): [ka] (In formula (3-2), R 2 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond or * 3 -CO-O-. 3 " is R 2 represents the bond to the carbon atom to which Ar is attached. 3 is a monovalent aromatic ring group. 2 is a divalent linking group. 1 is a divalent hydrocarbon group. + is a sulfonium cation or an iodonium cation. [Effects of the Invention]

[0013] According to the present invention, it is possible to obtain a radiation-sensitive composition that has high sensitivity, excellent CDU performance, and is capable of suppressing the occurrence of development defects. Furthermore, according to the method of forming a resist pattern of the present invention, a high-quality resist pattern can be formed by using the radiation-sensitive composition of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Matters related to the embodiments will be described in detail below. In this specification, a numerical range indicated using "to" means that the numerical values ​​before and after "to" are included as the lower and upper limits.

[0015] Here, in this specification, the term "hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "chain hydrocarbon group" refers to a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure and is composed solely of a chain structure. However, the chain hydrocarbon group may be saturated or unsaturated. The term "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic hydrocarbon structure as a ring structure and does not contain an aromatic ring structure. However, the alicyclic hydrocarbon group does not necessarily have to be composed solely of an alicyclic hydrocarbon structure and may also contain a chain structure as part of it. The term "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, the aromatic hydrocarbon group does not necessarily have to be composed solely of an aromatic ring structure and may contain a chain structure or an alicyclic hydrocarbon structure as part of it. The term "aromatic ring group" refers to an n-valent group obtained by removing n hydrogen atoms (where n is an integer of 1 or greater) from the ring portion of a substituted or unsubstituted aromatic ring. An "aromatic heterocyclic group" refers to an n-valent group formed by removing n (where n is an integer of 1 or more) hydrogen atoms from the ring portion of a substituted or unsubstituted aromatic heterocycle. An "organic group" refers to an atomic group formed by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound). An "aromatic ring" is intended to include aromatic hydrocarbon rings and aromatic heterocycles.

[0016] The "main chain" of a polymer refers to the "trunk" portion of the polymer, which is the longest chain of atoms. It is permissible for this "trunk" portion to contain a ring structure. For example, "having a specific structure in the main chain" means that the specific structure constitutes a part of the main chain of the polymer. A "side chain" refers to a portion branched from the "trunk" of the polymer. A "structural unit" refers to a unit that mainly constitutes the main chain structure, and at least two or more of which are contained in the main chain structure. A structural unit is typically a monomer unit. "(Meth)acrylate" is a term that includes "acrylate" and "methacrylate."

[0017] The expression "substituted or unsubstituted p-valent hydrocarbon group" (where p is an integer of 1 or greater) encompasses p-valent hydrocarbon groups (i.e., unsubstituted p-valent hydrocarbon groups) and groups in which p hydrogen atoms have been removed from the hydrocarbon structural portion of a substituted hydrocarbon group. Examples of substituted or unsubstituted p-valent hydrocarbon groups include alkyl groups and fluoroalkyl groups where p=1, and alkanediyl groups and fluoroalkanediyl groups where p=2. Of these, fluoroalkyl groups are "substituted monovalent hydrocarbon groups," and fluoroalkanediyl groups are "substituted divalent hydrocarbon groups." The same applies to other groups to which "substituted or unsubstituted" is attached.

[0018] ≪Radiation-sensitive composition≫ The radiation-sensitive composition of the present disclosure (hereinafter also referred to as "the composition") comprises a compound represented by the following formula (1): [ka] [In formula (1), Y 1 is expressed by the following formula (2-1) or formula (2-2): [ka] (In formula (2-1) and formula (2-2), Ar 1 is a divalent aromatic ring group. 2 is a single bond or a divalent aromatic ring group. 3 is a monovalent aromatic ring group. 1 and X 2 are each independently a divalent linking group. n is 0 or 1. 1 " represents a bond to the carbonyl group in formula (1). "*" represents a bond.) R is a divalent group represented by 1 is a divalent hydrocarbon group. + is a sulfonium cation or an iodonium cation. "*" represents a bond.] and a radiation-sensitive acid generator. Hereinafter, the polymer having the partial structure represented by the above formula (1) will also be referred to as "polymer (P)."

[0019] The present composition also contains one or more components having an iodine atom, and specifically satisfies one or more of the following requirements 1, 2, and 3. Requirement 1: The partial structure represented by the above formula (1) has two or more iodine atoms. Requirement 2: The radiation-sensitive acid generator contains an onium salt having two or more iodine atoms. Requirement 3: The partial structure represented by the above formula (1) contains an iodine atom, and the radiation-sensitive acid generator contains an onium salt containing an iodine atom.

[0020] <Partial structure represented by formula (1)> In the above formula (1), R 1 Examples of the divalent hydrocarbon group represented by the formula (I) include a linear or branched divalent saturated hydrocarbon group having 1 to 12 carbon atoms, a linear or branched divalent unsaturated hydrocarbon group having 2 to 12 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 12 carbon atoms, and a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms.

[0021] Specific examples of linear or branched divalent saturated hydrocarbon groups having 1 to 12 carbon atoms include methylene, ethylene, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl, butane-1,3-diyl, butane-2,3-diyl, hexane-1,6-diyl, etc. Specific examples of linear or branched divalent unsaturated hydrocarbon groups having 2 to 12 carbon atoms include alkenediyl groups such as ethenediyl, propenediyl, and butenediyl; and alkynediyl groups such as ethynediyl, propynediyl, and butynediyl.

[0022] Examples of divalent alicyclic hydrocarbon groups having 3 to 12 carbon atoms include groups having, as a ring structure, an alicyclic monocyclic hydrocarbon structure having 3 to 12 carbon atoms or an alicyclic polycyclic hydrocarbon structure having 6 to 12 carbon atoms. The alicyclic monocyclic hydrocarbon structure having 3 to 12 carbon atoms and the alicyclic polycyclic hydrocarbon structure having 6 to 12 carbon atoms may be saturated or unsaturated. The alicyclic polycyclic structure may be any of a bridged structure, a fused ring structure, and a spiro ring structure.

[0023] Examples of the ring contained in the alicyclic monocyclic hydrocarbon structure include a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, a cyclopentene ring, a cyclohexene ring, a cycloheptene ring, a cyclooctene ring, and a cyclodecene ring. The alicyclic polycyclic hydrocarbon structure is preferably a bridged alicyclic saturated hydrocarbon structure or a condensed alicyclic saturated hydrocarbon structure, such as a norbornane structure, a bicyclo[2.2.2]octane structure, and an adamantane structure.

[0024] Examples of divalent aromatic hydrocarbon groups having 6 to 12 carbon atoms include groups having, as a ring structure, an aromatic monocyclic hydrocarbon structure having 6 to 12 carbon atoms or an aromatic polycyclic hydrocarbon structure having 6 to 12 carbon atoms. Examples of the ring contained in the aromatic hydrocarbon group include a benzene ring and a naphthalene ring.

[0025] Sulfonic acid group (-SO3 - ) acidity can be reduced, and lithography performance (specifically, LWR (Line Width Roughness) performance and CDU performance) can be improved. 1 is preferably an alkanediyl group having 1 to 12 carbon atoms, more preferably an alkanediyl group having 1 to 8 carbon atoms, still more preferably an alkanediyl group having 1 to 6 carbon atoms, and particularly preferably an alkanediyl group having 1 to 3 carbon atoms.

[0026] Y 1 is a group represented by the above formula (2-1), Ar 1 or Ar 2 Examples of the divalent aromatic ring group represented by the formula include a group in which two hydrogen atoms have been removed from the ring portion of a substituted or unsubstituted aromatic hydrocarbon ring, and a group in which two hydrogen atoms have been removed from the ring portion of a substituted or unsubstituted aromatic heterocycle. Among these, a group in which two hydrogen atoms have been removed from the ring portion of a substituted or unsubstituted aromatic hydrocarbon ring is preferred. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring. Of these, a benzene ring or a naphthalene ring is preferred, and a benzene ring is more preferred. Ar 1 or Ar 2When the divalent aromatic ring group represented by the formula (I) has a substituent on the ring portion, examples of the substituent include an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a halogen atom (such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an acetyl group, a cyano group, and a nitro group.

[0027] Y 1 is a group represented by the above formula (2-2), Ar 3 Examples of the monovalent aromatic ring group represented by the formula (I) include a group in which one hydrogen atom has been removed from the ring portion of a substituted or unsubstituted aromatic hydrocarbon ring, and a group in which two hydrogen atoms have been removed from the ring portion of a substituted or unsubstituted aromatic heterocycle. Among these, a group in which one hydrogen atom has been removed from the ring portion of a substituted or unsubstituted aromatic hydrocarbon ring is preferred. Specific examples and preferred examples of the aromatic hydrocarbon ring and specific examples of the substituent include Ar 1 or Ar 2 The rings and groups are the same as those described for the divalent aromatic ring group represented by the following formula:

[0028] X 1 or X 2 Examples of the divalent linking group represented by the formula include -O-, -S-, -CO-, -COO-, -NH-, -CO-NH-, -SO2-, -(CH2) r -O-, -(CH2) r -O-(CH2) s -, an alkanediyl group having 1 to 3 carbon atoms (r and s are each independently an integer of 1 to 3). n is 0 or 1. When n is 0 and requirement 1 is satisfied, it is preferred in that a radiation-sensitive composition having superior sensitivity and CDU performance can be obtained. Also, when n is 1 and Y 1 is a group represented by the above formula (2-1), and the radiation-sensitive acid generator (particularly the acid generator described below) contained in the present composition contains an iodine atom, which is preferable in that a radiation-sensitive composition can be obtained that is capable of forming a resist pattern in which development defects are further suppressed.

[0029] M in the above formula (1) + is a sulfonium cation or an iodonium cation.+ In terms of increasing the sensitivity of the present composition, M is preferably an arylsulfonium cation or an aryliodonium cation, and more preferably a triarylsulfonium cation or a diaryliodonium cation. + is a diaryl iodonium cation and satisfies requirement 1, it is more preferable in that it is possible to increase the sensitivity of the composition and to obtain a radiation-sensitive composition with superior CDU performance while suppressing the occurrence of development defects in the resist pattern. + A triarylsulfonium cation is a cation in which one or more substituted or unsubstituted aryl groups are bonded to S + It represents a cation in which three substituted or unsubstituted aryl groups are bonded to I. Similarly, an aryliodonium cation is an I + A diaryliodonium cation is a cation in which one or more substituted or unsubstituted aryl groups are bonded to I + represents a cation having two substituted or unsubstituted aryl groups bonded to it.

[0030] In order to further increase the sensitivity of the present composition, it is preferable that the partial structure represented by the above formula (1) (hereinafter also referred to as the "specific partial structure") contains an iodine atom. The number of iodine atoms per specific partial structure is one or more. From the viewpoint of achieving both high sensitivity and improved CDU performance of the present composition, the number of iodine atoms per specific partial structure is more preferably two or more. Furthermore, from the viewpoint of ease of synthesis, the number of iodine atoms per specific partial structure is preferably six or less, more preferably four or less.

[0031] When the specific partial structure has an iodine atom, the anion portion in the above formula (1) (specifically, Y 1 ) may have an iodine atom, and the cationic moiety (i.e., M +) may have an iodine atom. In addition, both the anion moiety and the cation moiety in the above formula (1) may have an iodine atom. In order to obtain a radiation-sensitive composition with higher sensitivity, it is preferable that the iodine atom in the specific partial structure is bonded to an aromatic ring. The aromatic ring to which the iodine atom is bonded is preferably an aromatic hydrocarbon ring, more preferably a benzene ring or a naphthalene ring, and particularly preferably a benzene ring.

[0032] When the anionic portion in the specific partial structure has a plurality of iodine atoms, it is preferable that at least some of the iodine atoms are bonded to aromatic rings, and more preferably that all of the iodine atoms are bonded to aromatic rings.Furthermore, each of the iodine atoms in the anionic portion in the specific partial structure may be bonded to the same aromatic ring or different aromatic rings.Similarly, when the cationic portion in the specific partial structure has a plurality of iodine atoms, it is preferable that at least some of the iodine atoms are bonded to aromatic rings, and more preferably that all of the iodine atoms are bonded to aromatic rings.Each of the iodine atoms in the cationic portion in the specific partial structure may be bonded to the same aromatic ring or different aromatic rings.

[0033] When the anion moiety in the specific partial structure has an iodine atom, Ar 1 and Ar 2 one or both of which have an iodine atom as a substituent, or Ar 3 has an iodine atom as a substituent. When the anion moiety in the specific partial structure has an iodine atom, Ar 1 and Ar 2 Preferably, one or both of Ar 1 is a diiodophenylene group and satisfies requirement 1, or Ar 1 is a diiodophenylene group and satisfies requirement 3, or Ar 2 It is more preferable that Ar is an iodophenylene group and satisfies requirement 3. 1 and Ar 2In the above, the substitution position of the iodo group in the iodophenylene group and the diiodophenylene group is not particularly limited. The phenylene skeleton constituting the iodophenylene group and the diiodophenylene group may be any of a 1,4-phenylene group, a 1,3-phenylene group, and a 1,2-phenylene group. The cation moiety (i.e., M + ) has an iodine atom, M + may be an iodonium cation or a sulfonium cation having an iodine atom. The iodonium cation may further have an iodo group. The cationic moiety (i.e., M + ) has an iodine atom, M + preferably has two or more iodine atoms, and more preferably is an iodonium cation having one or more iodo groups (-I) or a sulfonium cation having two or more iodine atoms.

[0034] It is preferable that the cationic moiety in the specific partial structure has one or more iodine atoms, since this can enhance the effect of suppressing development defects. It is also preferable that the anionic moiety in the specific partial structure has one or more iodine atoms, since this can provide a radiation-sensitive composition with superior CDU performance. In particular, it is preferable that the cationic moiety in the specific partial structure has one or more iodine atoms and the anionic moiety has one or more iodine atoms, since this can provide a radiation-sensitive composition with superior CDU performance while suppressing development defects.

[0035] <Radiation-sensitive acid generator> A radiation-sensitive acid generator is a substance that generates an acid upon irradiation with radiation. A preferred radiation-sensitive acid generator is an onium salt having an onium cation (preferably a radiation-sensitive onium cation) and an organic anion that is the conjugate base of the acid. The organic anion is usually an anion formed by removing a proton from the acid group of an organic acid. In such a radiation-sensitive acid generator, the radiation-sensitive onium cation decomposes under the action of radiation to liberate an organic anion, which then bonds with hydrogen abstracted from a component contained in the composition (e.g., the radiation-sensitive acid generator itself or a solvent), thereby generating an acid derived from the organic anion.

[0036] The radiation-sensitive acid generator may be a so-called radiation-sensitive acid generator or an acid diffusion controller. The present composition may contain both an acid generator and an acid diffusion controller as the radiation-sensitive acid generator. The acid generator is a substance that, upon exposure, generates a strong acid in the present composition that is capable of cleaving an acid-dissociable group from a component in the radiation-sensitive composition. The acid diffusion controller is a substance that inhibits the diffusion of an acid generated by the acid generator upon exposure within the resist film, thereby inhibiting a chemical reaction caused by the acid in unexposed regions. The radiation-sensitive acid generator is classified as an acid generator or an acid diffusion controller depending on the strength of its acid relative to the components in the present composition (specifically, the polymer (P) and, when two or more radiation-sensitive acid generators are used, other radiation-sensitive acid generators). The acidity can be evaluated by the acid dissociation constant (pKa). For example, the acid dissociation constant of the acid generated by the acid diffusion controller is usually −3 or more, preferably −1≦pKa≦7, and more preferably 0≦pKa≦5.

[0037] The radiation-sensitive acid generator is a component different from the polymer (P). That is, the radiation-sensitive acid generator is a substance that does not have the partial structure represented by the above formula (1). Because it is easy to adjust the sensitivity of the composition and there is a high degree of freedom in selecting the radiation-sensitive acid generator to be blended in the composition, it is preferable to use a so-called low-molecular-weight compound (also called a non-polymer) that does not have a molecular weight distribution as the radiation-sensitive acid generator. The molecular weight of the radiation-sensitive acid generator is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0038] In order to enhance the sensitivity of the present composition, the present composition preferably contains an onium salt in which one or both of the onium cation and organic anion constituting the radiation-sensitive acid generator contain an iodine atom (hereinafter also referred to as an "iodine-containing onium salt"). The number of iodine atoms contained in the iodine-containing onium salt per molecule may be one or more. From the viewpoint of achieving both high sensitivity and improved CDU performance of the present composition, the number of iodine atoms contained in the iodine-containing onium salt is more preferably two or more. Furthermore, in consideration of the balance between sensitivity, CDU performance, and ease of synthesis, the number of iodine atoms contained in the iodine-containing onium salt is preferably 10 or less, more preferably 8 or less.

[0039] The bonding position of the iodine atom in the iodine-containing onium salt is not particularly limited. In order to obtain a radiation-sensitive composition with higher sensitivity, the iodine-containing onium salt preferably has a structure in which the iodine atom is bonded to an aromatic ring. The aromatic ring to which the iodine atom is bonded is preferably an aromatic hydrocarbon ring, more preferably a benzene ring or a naphthalene ring, and even more preferably a benzene ring.

[0040] When the iodine-containing onium salt has a plurality of iodine atoms, it is preferable that at least some of the iodine atoms are bonded to aromatic rings, and it is more preferable that all of the iodine atoms are bonded to aromatic rings. Furthermore, each of the iodine atoms in the iodine-containing onium salt may be bonded to the same aromatic ring or different aromatic rings in the iodine-containing onium salt.

[0041] The iodine-containing onium salt may be an onium salt in which at least one of the onium cation and the organic anion has an iodine atom. Therefore, the iodine-containing onium salt may be an onium salt in which the onium cation has an iodine atom and the organic anion does not have an iodine atom, or an onium salt in which the organic anion has an iodine atom and the onium cation does not have an iodine atom. The iodine-containing onium salt may also be an onium salt in which both the onium cation and the organic anion have an iodine atom. When the onium cation has an iodine atom, the onium cation may be an iodonium cation or a sulfonium cation having an iodine atom. The iodonium cation may further have an iodo group.

[0042] In the iodine-containing onium salt, the organic anion preferably has one or more iodine atoms, which can enhance the effect of suppressing the occurrence of development defects.Furthermore, the organic anion preferably has an aromatic ring substituted with two or more iodine groups, or an aromatic ring substituted with a fluoro group or a trifluoromethyl group, which can further improve the CDU performance.

[0043] The present composition may satisfy one or more of the above-mentioned requirements 1, 2, and 3. From the viewpoint of ease of adjusting sensitivity, it is preferable to satisfy at least one or both of requirements 1 and 2. Furthermore, from the viewpoint of being able to sufficiently obtain the effect of reducing development defects while improving sensitivity, it is more preferable to satisfy at least requirement 1.

[0044] The total number of iodine atoms per specific partial structure and the number of iodine atoms per molecule of the iodine-containing onium salt (hereinafter also referred to as the "total number Σ") may be at least 2. From the viewpoint of ensuring the solubility of the present composition and the ease of synthesis of the polymer or radiation-sensitive acid generator, the total number Σ is preferably 2 to 20, more preferably 2 to 15, even more preferably 2 to 12, and particularly preferably 3 to 12.

[0045] [Specific aspects of each component of the present composition] Next, the components contained in the present composition and the components that may be optionally blended will be described in more detail. Unless otherwise specified, each component contained in the present composition may be used alone or in combination of two or more.

[0046] <Polymer (P)> The polymer (P) may have the specific partial structure in a side chain, or at one or both ends of the polymer. In terms of being able to form a resist pattern with fewer development defects, the polymer (P) preferably contains a structural unit having the specific partial structure (hereinafter also referred to as "structural unit (I)").

[0047] (Structural unit (I)) The structural unit (I) is preferably a structural unit derived from an onium salt having a polymerizable unsaturated bond and the partial structure represented by the above formula (1). A preferred specific example of the structural unit (I) is a structural unit represented by the following formula (3): [ka] (In formula (3), R 2 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond or * 2 -CO-O-(「* 2 " represents the bond to the main chain). Y 1 , R 1 and M + is the same as the above formula (1).

[0048] In the above formula (3), R 2 From the viewpoint of copolymerizability, A is preferably a hydrogen atom or a methyl group. 1 , Y 1 and R 1 Specific and preferred examples are as explained above in relation to formula (1).

[0049] M +Preferred specific examples include cations represented by the following formula (4), cations represented by the following formula (5), and cations represented by the following formula (6). [ka] (In formula (4), R 1a and R 2a are each independently a monovalent substituent, or R 1a and R 2a are combined together to represent a single bond or a divalent group connecting the rings to which they are attached. 3a is a monovalent substituent. a1 and a2 are each independently an integer of 0 to 5. a3 is an integer of 0 to (2×r+5). r is 0 or 1. In formula (5), R 4a and R 5a a4 and a5 are each independently an integer of 0 to 5. In formula (6), a6 is an integer of 0 to 7. When a6 is 1, R 6a is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen group. When a6 is 2 or more, a plurality of R 6a 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 group, or a plurality of R 6a When two of the groups are combined together with the carbon atoms to which they are bonded, they form a ring structure having 4 to 20 ring members. a7 is an integer of 0 to 6. When a7 is 1, R 7a is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen group. When a7 is 2 or more, a plurality of R 7a 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 group, or a plurality of R 7a Two of these are combined together to form a ring structure having 3 to 20 ring members, together with the carbon atoms to which they are attached. t1 is an integer of 0 to 3. R 8a represents a single bond or a divalent organic group having 1 to 20 carbon atoms. t2 is 0 or 1.

[0050] In the above formulas (4) and (5), R 1a , R 2a , R 3a , R 4a and R 5a (Hereinafter referred to as “R 1a ~R 5a "). Examples of the monovalent substituent represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted cycloalkyloxy group, an ester group, an alkylsulfonyl group, a cycloalkylsulfonyl group, a hydroxy group, a carboxy group, a cyano group, and a nitro group.

[0051] R 1a ~R 5a The alkyl group represented by the formula (I) may be linear or branched. The alkyl group preferably has 1 to 10 carbon atoms. Among these, R 1a ~R 5a The alkyl group represented by the formula (I) preferably has 1 to 5 carbon atoms, and more preferably is a methyl group, an ethyl group, an n-butyl group, or a t-butyl group. 1a ~R 5a Specific examples of when is an alkoxy group include groups having the alkyl group exemplified above in the alkyl group moiety constituting the alkoxy group. The alkoxy group is preferably a methoxy group, an ethoxy group, an n-propoxy group, or an n-butoxy group.

[0052] R 1a ~R 5a The cycloalkyl group represented by the formula (I) may be either monocyclic or polycyclic. Among these, examples of monocyclic cycloalkyl groups include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. Examples of polycyclic cycloalkyl groups include a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group. R 1a ~R 5aSpecific examples of when R is a cycloalkyloxy group include groups having the above-mentioned cycloalkyl groups in the cycloalkyl group moiety that constitutes the cycloalkyloxy group. 1a ~R 5a The cycloalkyloxy group represented by the following formula is preferably a cyclopentyloxy group or a cyclohexyloxy group.

[0053] R 1a ~R 5a When has a substituent, examples of the substituent include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, and an alkoxy group having 1 to 5 carbon atoms.

[0054] R 1a ~R 5a When R is an ester group (-COOR), examples of the hydrocarbon portion (R) of the ester group include the substituted or unsubstituted alkyl groups or substituted or unsubstituted cycloalkyl groups exemplified above. 1a ~R 5a is an ester group, R 1a ~R 5a is preferably a methoxycarbonyl group, an ethoxycarbonyl group, or an n-butoxycarbonyl group. 1a ~R 5a When R is an alkylsulfonyl group, the alkyl group moiety constituting the alkylsulfonyl group may be the substituted or unsubstituted alkyl group exemplified above. 1a ~R 5a When is a cycloalkylsulfonyl group, the cycloalkyl group moiety constituting the cycloalkylsulfonyl group includes the substituted or unsubstituted cycloalkyl groups exemplified above.

[0055] R 1a and R 2aWhen R are combined with each other to represent a divalent group connecting the rings to which they are bonded, examples of the divalent group include -COO-, -OCO-, -CO-, -O-, -SO-, -SO2-, -S-, an alkanediyl group having 1 to 3 carbon atoms, an alkenediyl group having 2 or 3 carbon atoms, and a group having -O-, -S-, -COO-, -OCO-, -CO-, -SO-, or -SO2- between the carbon-carbon bonds of an ethylene group. 1a and R 2a is preferably a single bond connecting the rings, or forms -O- or -S-.

[0056] Each of a1, a2, and a3 is preferably an integer of 0 to 2. In order to further increase the sensitivity of the radiation-sensitive composition, it is preferable that a1+a2+a3≧1 and R 1a , R 2a and R 3a At least one of the groups is preferably at least one selected from the group consisting of a fluorine atom, an iodine atom, and a trifluoromethyl group. Each of a4 and a5 is preferably an integer of 0 to 2. In order to further increase the sensitivity of the radiation-sensitive composition, it is preferable that a4+a5≧1 and R 4a and R 5a At least one of the groups is preferably at least one selected from the group consisting of a fluorine atom, an iodine atom, and a trifluoromethyl group.

[0057] In the above formula (6), R 6a and R 7a The monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) includes a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, -OR k , -COOR k , -O-CO-R k , -OR kk -COOR k , -R kk -CO-R k , -OSO2-R k or -SO2-R k etc. Rk is a monovalent hydrocarbon group having 1 to 10 carbon atoms. kk R is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms. 6a and R 7a In the above, the substituents that substitute the hydrogen atoms of the hydrocarbon group include the above R 1a ~R 5a Examples of the substituent that the group represented by the following formula (I) has include the same groups as those exemplified above. R 8a Examples of the divalent organic group represented by the formula include R 6a and R 7a Examples of such groups include groups in which one hydrogen atom has been removed from the monovalent organic groups having 1 to 20 carbon atoms exemplified as above.

[0058] R 6a and R 7a is a fluorine atom, an iodine atom, a linear or branched monovalent alkyl group, a monovalent fluoroalkyl group, a monovalent aromatic hydrocarbon group, -OSO2-R k or -SO2-R k a6 is preferably an integer of 0 to 2, more preferably 0 or 1. a7 is preferably an integer of 0 to 2, more preferably 0 or 1. t2 is preferably 0. t1 is preferably 2 or 3.

[0059] M + Specific examples of M include cations represented by the following formulae: + is not limited to these. [ka] [ka] [ka] [ka] [ka] [ka]

[0060] Specific examples of the structural unit (I) include structural units represented by the following formulas. However, the structural unit (I) is not limited to the following specific examples. + " is a monovalent cation, and specific examples thereof include the cations exemplified above. [ka] [ka] (In the formula, R 2 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. + is a sulfonium cation or an iodonium cation.

[0061] The content of the structural unit (I) in the polymer (P) is preferably 1 mol % or more, more preferably 2 mol % or more, and even more preferably 5 mol % or more, based on all structural units constituting the polymer (P), from the viewpoint of increasing the sensitivity of the radiation-sensitive composition and sufficiently improving CDU performance and suppressing development defects. Furthermore, from the viewpoint of ensuring that the radiation-sensitive composition exhibits good CDU performance, the content of the structural unit (I) is preferably 50 mol % or less, more preferably 40 mol % or less, and even more preferably 30 mol % or less, based on all structural units constituting the polymer (P). By setting the content of the structural unit (I) within the above range, it is possible to sufficiently achieve the effect of reducing the occurrence of development defects while maintaining high sensitivity and good CDU performance.

[0062] (Other structural units) The polymer (P) may further contain structural units different from the structural unit (I) (hereinafter also referred to as "other structural units"). Examples of the other structural units include the following structural units (II) to (IV). Structural unit (II): a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring Structural unit (III): a structural unit having an acid-dissociable group Structural unit (IV): a structural unit having a lactone structure, a cyclic carbonate structure, a sultone structure, or a heterocyclic structure formed by combining two or more of these structures Structural unit (V): a structural unit having an alcoholic hydroxyl group In this specification, a structural unit having a hydroxyl group and an acid-dissociable group bonded to an aromatic ring is classified as structural unit (III).

[0063] Structural Units (II) The structural unit (II) is a structural unit having an aromatic ring and a hydroxy group bonded to the aromatic ring (excluding the structural unit (I) and structural units having an acid-dissociable group). The polymer (P) further containing the structural unit (II) is advantageous in that it can improve the resolution of the composition, highly effectively inhibits dissolution of unexposed areas into a developer, and sufficiently reduces development defects. In particular, polymers having a hydroxy group bonded to an aromatic ring are preferably used in pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV.

[0064] Examples of aromatic rings to which hydroxy groups are bonded include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring. Of these, a benzene ring or a naphthalene ring is preferred, and a benzene ring is more preferred. The number of hydroxy groups bonded to the aromatic ring is not particularly limited. The number of hydroxy groups bonded to the aromatic ring is preferably 1 to 3, and more preferably 1 or 2. The position of the hydroxy group bonded to the aromatic ring is also not particularly limited. For example, when the structural unit (II) has a hydroxy group bonded to a benzene ring, the bonding position of the hydroxy group on the benzene ring in the structural unit (II) may be any of the ortho-, meta-, and para-positions relative to other groups.

[0065] The aromatic ring to which the hydroxy group is bonded may further have a substituent different from the hydroxy group bonded thereto, such as an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

[0066] Specific examples of the structural unit (II) include a structural unit represented by the following formula (7). [ka] (In formula (7), R 71 is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. 8 represents a single bond, -O-, -CO-, * 4 -COO- or * 4 -CONH-. 4 " represents the bond to the main chain. Y 6 is a monovalent group having a hydroxyl group bonded to an aromatic ring.

[0067] In the above formula (7), R 71 From the viewpoint of copolymerizability of the monomer that gives the structural unit (II), L is preferably a hydrogen atom or a methyl group. 8 is a single bond or * 4 -COO- is preferred, and a single bond is more preferred in that it can further increase the sensitivity of the present composition. 6 is preferably a group in which one hydrogen atom has been removed from the ring portion of the aromatic ring to which the hydroxy group is bonded (i.e., a monovalent aromatic ring group substituted with a hydroxy group). 6 The aromatic ring in the ring may further have a substituent other than a hydroxy group, specific examples of which are as described above.

[0068] Further specific examples of the structural unit (II) include structural units represented by the following formulas. [ka] (In the formula, R 71 is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group.

[0069] When the polymer (P) contains the structural unit (II), the content of the structural unit (II) is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more, based on the total amount of structural units constituting the polymer (P). The content of the structural unit (II) is preferably 60 mol% or less, more preferably 50 mol% or less, and even more preferably 45 mol% or less, based on the total amount of structural units constituting the polymer (P). By setting the content of the structural unit (II) within the above range, the resolution of the composition can be further improved, which is preferable.

[0070] Structural unit (III) The acid-dissociable group in the structural unit (III) is a group that substitutes a hydrogen atom in an acid group such as a carboxy group or a hydroxy group, and dissociates under the action of an acid. By incorporating a polymer having an acid-dissociable group into the composition, the acid-dissociable group dissociates in the presence of acid generated by exposure, generating an acid group, thereby changing the solubility of the polymer component in a developer. This allows the composition to have good lithography properties (specifically, LWR performance and CDU (Critical Dimension Uniformity) performance), enabling the formation of good resist patterns.

[0071] The structural unit (III) is not particularly limited as long as it has an acid-dissociable group. Examples of the structural unit (III) include a structural unit represented by the following formula (8-1) (hereinafter also referred to as "structural unit (3A)"), a structural unit represented by the following formula (8-2) (hereinafter also referred to as "structural unit (3B)"), and a structural unit represented by the following formula (8-3) (hereinafter also referred to as "structural unit (3C)"). [ka] (In formula (8-1), R 72 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 5 R is a divalent chain organic group or an alicyclic hydrocarbon group. 73R is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. 74 and R 75 are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic heterocyclic group, or R 74 and R 75 are aligned with each other and R 74 and R 75 represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which R is bonded. 73 If is a hydrogen atom, R 74 and R 75 or both of R are, independently of each other, a substituted or unsubstituted monovalent unsaturated hydrocarbon group, a monovalent aromatic heterocyclic group, or 74 and R 75 are aligned with each other and R 74 and R 75 represents an alicyclic unsaturated hydrocarbon structure having 3 to 20 carbon atoms formed together with the carbon atom to which it is bonded. g1 is 0 or 1. In formula (8-2), R 76 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 6 represents a single bond, -O-, -CO-, * 5 -COO- or * 5 -CONH-. 5 " represents the bond to the main chain. R 77 , R 78 and R 79 are each independently a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted monovalent oxyhydrocarbon group having 1 to 20 carbon atoms. 35 is a monovalent substituent. g2 is an integer of 0 to 4. In formula (8-3), R 31 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 7 represents a single bond, -O-, -CO-, * 6 -COO- or * 6 -CONH-. 6 " represents the bond to the main chain. R 32R is a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted monovalent oxyhydrocarbon group having 1 to 20 carbon atoms. 33 and R 34 are each independently a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted monovalent oxyhydrocarbon group having 1 to 20 carbon atoms, or R 33 and R 34 are aligned with each other and R 33 and R 34 represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which R is bonded. 36 is a monovalent substituent. g3 is an integer of 0 to 4.

[0072] In the above formula (8-1), R 72 In view of the copolymerizability of the monomer that gives the structural unit (3A), R is preferably a hydrogen atom or a methyl group, and more preferably a methyl group. 76 is preferably a hydrogen atom from the viewpoint of copolymerizability of the monomer that gives the structural unit (3B). 31 is preferably a hydrogen atom or a methyl group. 6 Or L in formula (8-3) 7 is a single bond, * 6 -COO- or * 6 -CONH- is preferred.

[0073] L in the above formula (8-1) 5 Examples of the divalent chain organic group represented by the formula (I) include a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, and a divalent group having 2 to 20 carbon atoms in which a methylene group contained in a chain or branched saturated hydrocarbon group has been replaced with a heteroatom-containing group (for example, -O-, -S-, -CO-, -COO-, -NH-, -NHCO-, -SO2-). 5 Specific and preferred examples of the divalent alicyclic hydrocarbon group represented by R 73 ~R 75 , R 77 ~R 79 or R 32 ~R34 Examples of the monovalent alicyclic hydrocarbon group represented by the formula L include the same groups as those exemplified below. 5 is preferably a chain organic group.

[0074] R 73 ~R 75 , R 77 ~R 79 or R 32 ~R 34 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0075] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, and t-butyl; alkenyl groups such as ethenyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl. 73 ~R 75 , R 77 ~R 79 or R 32 ~R 34 The monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by the following formula is preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms.

[0076] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monovalent monocyclic alicyclic saturated hydrocarbon groups such as a cyclopentyl group, a cyclohexyl group, a methylcyclopentyl group, an ethylcyclopentyl group, a methylcyclohexyl group, and an ethylcyclohexyl group; monovalent monocyclic unsaturated hydrocarbon groups such as a cyclopentenyl group, a cyclohexenyl group, a methylcyclopentenyl group, and a methylcyclohexenyl group; monovalent polycyclic saturated alicyclic hydrocarbon groups such as a norbornyl group, an adamantyl group, and a tricyclodecyl group; and monovalent polycyclic unsaturated alicyclic hydrocarbon groups such as a norbornenyl group, a tricyclodecenyl group, and an indanyl group.

[0077] 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 mesityl group, a naphthyl group, a methylnaphthyl group, an anthryl group, a methylanthryl group, and an indenyl group; and aralkyl groups such as a benzyl group, a phenethyl group, a naphthylmethyl group, and an anthrylmethyl group.

[0078] R 73 or R 74 Examples of the monovalent unsaturated hydrocarbon group represented by the formula (I) include the above-mentioned monocyclic or polycyclic alicyclic unsaturated hydrocarbon group and aromatic hydrocarbon group. Examples of the monovalent aromatic heterocyclic group include a furyl group and a thienyl group.

[0079] R 74 and R 75 are aligned with each other and R 74 and R 75 an alicyclic hydrocarbon structure having 3 to 20 carbon atoms formed together with the carbon atom to which R is bonded, and 33 and R 34 are aligned with each other and R 33 and R 34 Examples of the alicyclic hydrocarbon structure having 3 to 20 carbon atoms constituted together with the carbon atom to which it is bonded include monocyclic alicyclic saturated hydrocarbon structures such as a cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cycloheptane structure, and cyclooctane structure; monocyclic alicyclic unsaturated hydrocarbon structures such as cyclopentene and cyclohexene; and polycyclic alicyclic hydrocarbon structures such as a norbornane structure, adamantane structure, tricyclodecane structure, and tetracyclododecane structure.

[0080] R 77 ~R 79 or R 32 ~R 34 Examples of the monovalent oxyhydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include the above-mentioned R 73 ~R 75 , R 77 ~R 79 and R 32 ~R 34Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include groups containing an oxygen atom at the bond-side terminal of the groups exemplified by R 77 ~R 79 or R 32 ~R 34 Of these, the monovalent oxyhydrocarbon group represented by the following formula is preferably an alkoxy group, a cycloalkoxy group, or a cycloalkylalkoxy group.

[0081] R 73 ~R 75 , R 77 ~R 79 or R 32 ~R 34 When the group represented by the formula (I) has a substituent, examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), a hydroxyl group, an alkoxy group having 1 to 3 carbon atoms, etc. 74 and R 75 are aligned with each other and R 74 and R 75 When R forms an alicyclic hydrocarbon structure having 3 to 20 carbon atoms together with the carbon atom to which it is bonded, or 33 and R 34 are aligned with each other and R 33 and R 34 When the ring forms an alicyclic hydrocarbon structure having 3 to 20 carbon atoms together with the carbon atom to which it is bonded, the above-exemplified substituents and alkyl groups may be bonded to the ring.

[0082] R 35 or R 36 Examples of the monovalent substituent represented by the formula (I) include an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. g2 and g3 each preferably represent an integer of 0 to 2, and more preferably 0 or 1.

[0083] It is preferable that at least a portion of the structural unit (III) has at least one group (hereinafter also referred to as "specific group") selected from the group consisting of iodine atom, fluorine atom, and trifluoromethyl group, since this can improve the CDU performance while increasing the sensitivity of the present composition. In the structural unit (III), the specific group is preferably bonded to an aromatic ring, and more preferably, the acid-dissociable group has an aromatic ring and the specific group is bonded to the aromatic ring. The number of specific groups in the monomer that gives the structural unit (III) (the total number when two or more types are present) is preferably 1 to 10, more preferably 1 to 6.

[0084] Specific examples of the structural unit (3A) include structural units represented by the following formulas. [ka] [ka] [ka] (In the formula, R 72 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0085] Specific examples of the structural unit (3B) include structural units represented by the following formulas. [ka] (In the formula, R 76 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0086] Specific examples of the structural unit (3C) include structural units represented by the following formulas. [ka] [ka] (In the formula, R 31is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0087] Other examples of the structural unit (III) include structural units derived from compounds in which the two carboxy groups of an unsaturated dicarboxylic acid are protected (for example, di-tert-butyl maleate).

[0088] In order to further enhance the sensitivity of the composition, the content of the structural unit (III) in the polymer (P) is preferably 10 mol% or more, more preferably 30 mol% or more, even more preferably 50 mol% or more, and even more preferably 60 mol% or more, based on the total amount of structural units constituting the polymer (P). Furthermore, the content of the structural unit (III) is preferably 85 mol% or less, more preferably 80 mol% or less, and even more preferably 75 mol% or less, based on the total amount of structural units constituting the polymer (P). By setting the content of the structural unit (III) within the above range, the difference in dissolution rate in a developer between the exposed and unexposed areas can be increased while maintaining good sensitivity of the composition, thereby enabling the pattern shape of the resist film to be improved.

[0089] Structural unit (IV) The structural unit (IV) is a structural unit having a lactone structure, a cyclic carbonate structure, a sultone structure, or a ring structure formed by combining two or more of these (excluding the structural units (I) to (III)).

[0090] Specific examples of the structural unit (IV) include structural units represented by the following formulas: [ka] [ka] [ka] (In the formula, R L1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0091] When polymer (P) contains structural unit (IV), the content of structural unit (IV) is preferably 1 mol% or more, more preferably 2 mol% or more, based on the total amount of structural units contained in polymer (P). The content of structural unit (IV) in polymer (P) is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less, based on the total amount of structural units contained in polymer (P).

[0092] Structural unit (V) The structural unit (V) may further contain a structural unit having an alcoholic hydroxyl group (excluding the structural units (I) to (IV)). By introducing the structural unit (V) into the polymer (P), it is possible to further improve the effect of suppressing development defects when a resist pattern is formed using the composition. Here, in this specification, the term "alcoholic hydroxyl group" refers to a group having a structure in which a hydroxyl group is directly bonded to an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a chain hydrocarbon group or an alicyclic hydrocarbon group.

[0093] The structural unit (V) is preferably a structural unit derived from an unsaturated monomer having an alcoholic hydroxyl group. The structure of the unsaturated monomer that gives the structural unit (V) is not particularly limited as long as it has an alcoholic hydroxyl group. Specific examples of the structural unit (V) include structural units represented by the following formula: [ka] (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0094] When the polymer (P) contains the structural unit (V), from the viewpoint of fully obtaining the effect of suppressing development defects by introducing the structural unit (V), the content of the structural unit (V) is preferably 1 mol % or more relative to the total amount of structural units constituting the polymer (P). Furthermore, from the viewpoint of increasing the development contrast between exposed and unexposed areas, the content of the structural unit (V) is preferably 20 mol % or less, more preferably 10 mol % or less, relative to the total amount of structural units constituting the polymer (P).

[0095] In addition to the above, examples of structural units contained in the polymer (P) include structural units containing a cyano group, a nitro group, or a sulfonamide group (specifically, a structural unit derived from 2-cyanomethyladamantan-2-yl(meth)acrylate, etc.); structural units containing a non-acid-dissociable hydrocarbon group (specifically, a structural unit derived from substituted or unsubstituted styrene (e.g., a styrene unit, a bromostyrene unit, etc.), a structural unit derived from vinylnaphthalene, a structural unit derived from n-pentyl(meth)acrylate, etc.). The content ratio of these structural units can be appropriately set depending on each structural unit, as long as the effects of the present disclosure are not impaired.

[0096] In order to improve the sensitivity and CDU performance of the composition, the polymer (P) preferably contains an iodine atom, and more preferably contains a structural unit having an iodine atom. The structural unit having an iodine atom may be the structural unit (I) or another structural unit (e.g., the structural unit (II) or the structural unit (III)).

[0097] In order to fully obtain the effect of improving the sensitivity of the composition, the content of the structural units having iodine atoms in the polymer (P) is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more, based on the total amount of structural units constituting the polymer (P). Furthermore, the content of the structural units having iodine atoms is preferably 80 mol% or less, more preferably 70 mol% or less, based on the total amount of structural units constituting the polymer (P). In the structural units having iodine atoms, the iodine atoms are preferably bonded to an aromatic ring.

[0098] The weight average molecular weight (Mw) of the polymer (P) measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and even more preferably 4,000 or more. Furthermore, the Mw of the polymer (P) is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, and even more preferably 15,000 or less. By setting the Mw of the polymer (P) within the above range, the coatability of the composition can be improved and development defects can be sufficiently suppressed, which is advantageous.

[0099] The ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the polymer (P) measured by GPC (Mw / Mn, hereinafter also referred to as "dispersity") is preferably 5.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less. Mw / Mn is usually 1.0 or more.

[0100] The polymer (P) preferably constitutes the base resin of the composition. Herein, the term "base resin" refers to a component that accounts for more than 50% by mass of the total amount of solids contained in the composition. In this specification, the term "total amount of solids" refers to the sum of all components other than the solvent. The content of the polymer (P) in the composition is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 85% by mass or more, of the total amount of solids contained in the composition.

[0101] [Radiation-sensitive acid generator] Acid generator For the purpose of further improving the sensitivity and CDU performance of the composition, the composition may contain an acid generator as a radiation-sensitive acid generator. The acid generator generates a strong acid that induces dissociation of the acid-dissociable group under normal conditions upon exposure. Here, "normal conditions" refers to post-exposure baking (PEB) at 110°C for 60 seconds. The acid generator is a component different from the polymer (P). The molecular weight of the acid generator is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0102] The type of acid generator to be incorporated into the composition is not particularly limited, and known radiation-sensitive acid generators used in resist pattern formation can be used as appropriate. The acid generator may be an ionic radiation-sensitive acid generator or a nonionic radiation-sensitive acid generator. An ionic radiation-sensitive acid generator, such as an onium salt composed of a radiation-sensitive onium cation and an organic anion, is preferred. The acid generator is preferably a compound that generates an acid (preferably a strong acid such as a sulfonic acid, imidic acid, or methide acid) in the composition under the above-mentioned normal conditions that is more acidic than the acid generated by the acid diffusion controller (more specifically, the photodegradable base), thereby inducing dissociation of the acid-dissociable group.

[0103] When an onium salt is used as the acid generator, from the viewpoint of increasing the sensitivity of the present composition and forming a resist film with excellent lithography performance, the acid generator preferably has a sulfonium cation or an iodonium cation, and more preferably an arylsulfonium cation or an aryliodonium cation. Specific examples of these include the cations represented by the above formula (4), the cations represented by the above formula (5), and the cations represented by the above formula (6). Further specific examples of the radiation-sensitive onium cation contained in the acid generator include the same cations as those listed as specific examples of the cations represented by the above formula (4), the cations represented by the above formula (5), and the cations represented by the above formula (6). When the above formula (4) or (6) has an iodo group as a substituent, the sulfonium cation and the iodonium cation represented by the above formula (5) are also specific examples of the onium cation contained in the iodine-containing onium salt when the acid generator is an iodine-containing onium salt. Among these, sulfonium cations having an aromatic ring substituted with an iodine atom and iodonium cations having an aromatic ring to which an iodo group is bonded are preferred in that they can provide a radiation-sensitive composition having higher sensitivity while suppressing development defects.

[0104] The organic anion contained in the acid generator is usually an anion obtained by removing a proton from the acid group contained in the organic acid. The organic anion is not particularly limited, but a sulfonate anion, an imide anion, or a methide anion is preferred in terms of increasing the sensitivity of the composition. For example, specific examples of sulfonate anions include anions represented by the following formulas. In addition, when the acid generator is an iodine-containing onium salt, the anion having an iodine atom in the following formulas is also a specific example of the organic anion contained in the iodine-containing onium salt. [ka]

[0105] [ka]

[0106] [ka]

[0107] When an acid generator is incorporated into the composition, the content of the acid generator is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of polymer (P), from the viewpoint of fully obtaining the effect of improving sensitivity due to the incorporation of the acid generator. Furthermore, from the viewpoint of suppressing the occurrence of development defects caused by the acid generator, the content of the acid generator is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, relative to 100 parts by mass of polymer (P).

[0108] When an acid generator is incorporated into the present composition, an onium salt having an iodine atom (i.e., an iodine-containing onium salt) can be preferably used as the acid generator, since this can improve the sensitivity, CDU performance, and development defect suppression properties of the present composition in a well-balanced manner. In the acid generator having an iodine atom, the number of iodine atoms in one molecule is preferably 2 or more, and more preferably 3 or more, from the viewpoint of improving the CDU performance of the radiation-sensitive composition.

[0109] Acid diffusion control agent The acid diffusion controller is a substance that can suppress acid-induced chemical reactions in unexposed areas by inhibiting the diffusion of acid generated in the resist film upon exposure of the composition. The acid diffusion controller generates a weak acid upon exposure that does not induce dissociation of acid-dissociable groups under the above-mentioned normal conditions. The lithography properties of the composition may be further improved by incorporating such an acid diffusion controller into the composition. The acid diffusion controller referred to here is a component different from the polymer (P). The molecular weight of the acid diffusion controller is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0110] As the acid diffusion controller, an onium salt (hereinafter also referred to as a "photodegradable base") composed of an onium cation (more specifically, a radiation-sensitive onium cation) and an organic anion can be preferably used. From the viewpoint of improving the lithography properties of the present composition, the present composition preferably contains a photodegradable base as a radiation-sensitive acid generator. The photodegradable base is preferably an onium salt that generates a carboxylic acid, a sulfonic acid, or a sulfonamide upon exposure. Furthermore, from the viewpoint of being able to form a resist film with higher lithography performance, an onium salt having a sulfonium cation or an iodonium cation can be preferably used as the photodegradable base.

[0111] Specific examples of the onium cation contained in the photodegradable base include the cation represented by the above formula (4), the cation represented by the above formula (5), and the cation represented by the above formula (6). Further specific examples of the onium cation contained in the photodegradable base include the same cations as those given as specific examples of the cation represented by the above formula (4), the cation represented by the above formula (5), and the cation represented by the above formula (6). Note that when the above formula (4) or (6) has an iodo group as a substituent, the sulfonium cation and the iodonium cation represented by the above formula (5) are also specific examples of the onium cation contained in the iodine-containing onium salt when the photodegradable base is an iodine-containing onium salt. Among these, the onium cation contained in the photodegradable base is preferably a sulfonium cation having an aromatic ring substituted with an iodine atom, or an iodonium cation having an aromatic ring to which an iodo group is bonded.

[0112] Examples of the organic anion possessed by the photodegradable base include anions represented by the following formula: In addition, in the following formula, the anion having an iodine atom is also a specific example of the organic anion possessed by the iodine-containing onium salt when the photodegradable base is an iodine-containing onium salt. The organic anion possessed by the photodegradable base is preferably a carboxylate anion having an aromatic ring substituted with an iodine atom. [ka]

[0113] When an acid diffusion controller is incorporated into the composition, the content of the acid diffusion controller is preferably 1 part by mass or more, more preferably 2 parts by mass or more, per 100 parts by mass of polymer (P), from the viewpoint of fully obtaining the effects of the acid diffusion controller in improving sensitivity and lithography performance. Furthermore, from the viewpoint of suppressing development defects caused by the acid diffusion controller, the content of the acid diffusion controller is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, per 100 parts by mass of polymer (P).

[0114] When an acid diffusion controller is incorporated into the composition, the content of the acid diffusion controller in the composition is preferably 2 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, based on the total amount of the acid generator and the monomer that provides the structural unit (I) contained in the composition. Furthermore, the content of the acid diffusion controller is preferably 90 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less, based on the total amount of the acid generator and the monomer that provides the structural unit (I) contained in the composition. By ensuring that the content of the acid diffusion controller falls within the above range, the CDU performance of the composition can be further improved.

[0115] Preferred specific embodiments of the polymer (P) and the radiation-sensitive acid generator in the present composition that satisfy one or more of requirements 1, 2, and 3 include the following. Aspect 1: An aspect comprising a polymer (P) and an acid diffusion controller, optionally containing an acid generator, and in which the structural unit (I) in the polymer (P) has two or more iodine atoms. Aspect 2: A configuration comprising a polymer (P) and an acid diffusion controller, optionally containing an acid generator, and wherein the acid diffusion controller has two or more iodine atoms. Aspect 3: A configuration comprising a polymer (P), an acid generator, and an acid diffusion controller, wherein the acid generator has two or more iodine atoms. Aspect 4: An aspect comprising a polymer (P) and an acid diffusion controller, optionally containing an acid generator, wherein the structural unit (I) in the polymer (P) has one or more iodine atoms, and the acid diffusion controller has one or more iodine atoms. Aspect 5: An aspect comprising a polymer (P), an acid generator, and an acid diffusion controller, wherein the structural unit (I) in the polymer (P) has one or more iodine atoms, and the acid generator has one or more iodine atoms.

[0116] The above-mentioned embodiments 1 to 5 may further contain other components. In addition, in embodiment 1, the acid diffusion controller may have an iodine atom, and in embodiment 2, the structural unit (I) in the polymer (P) may have an iodine atom. In addition, in embodiments 1, 2, and 4, the optionally contained acid generator may have an iodine atom.

[0117] [Other ingredients] The present composition may further contain, in addition to the polymer (P) and the radiation-sensitive acid generator, components other than the polymer (P) and the radiation-sensitive acid generator (hereinafter also referred to as "other components"). Examples of other components include a solvent, a high-fluorine-containing polymer, etc.

[0118] (solvent) The solvent is preferably one that can dissolve or disperse the components to be blended in the composition, and organic solvents are preferably used. Specific examples of the solvent include alcohols, ethers, ketones, amides, esters, and hydrocarbons.

[0119] Examples of alcohols include aliphatic monoalcohols having 1 to 18 carbon atoms, such as 4-methyl-2-pentanol and n-hexanol; alicyclic monoalcohols having 3 to 18 carbon atoms, such as cyclohexanol; polyhydric alcohols having 2 to 18 carbon atoms, such as 1,2-propylene glycol; and partial ethers of polyhydric alcohols having 3 to 19 carbon atoms, such as propylene glycol monomethyl ether. Examples of ethers include dialkyl ethers, such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether; cyclic ethers, such as tetrahydrofuran and tetrahydropyran; and aromatic ring-containing ethers, such as diphenyl ether and anisole.

[0120] Examples of ketones include chain ketones such as acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, methyl isobutyl ketone, 2-heptanone, ethyl n-butyl ketone, methyl n-hexyl ketone, di-isobutyl ketone, and trimethylnonanone; cyclic ketones such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone; 2,4-pentanedione, acetonylacetone, acetophenone, and diacetone alcohol. Examples of amides include cyclic amides such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain amides such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0121] Examples of esters include monocarboxylic acid esters such as n-butyl acetate, ethyl lactate, and methyl 2-hydroxyisobutyrate; polyhydric alcohol carboxylates such as propylene glycol diacetate; polyhydric alcohol partial ether carboxylates such as propylene glycol monomethyl ether acetate; polycarboxylic acid diesters such as diethyl oxalate; carbonates such as dimethyl carbonate and diethyl carbonate; and cyclic esters such as γ-butyrolactone. Examples of hydrocarbons include aliphatic hydrocarbons having 5 to 12 carbon atoms such as n-pentane and n-hexane; and aromatic hydrocarbons having 6 to 16 carbon atoms such as toluene and xylene.

[0122] Of these, the solvent preferably contains at least one selected from the group consisting of esters and ketones, and more preferably contains at least one selected from the group consisting of polyhydric alcohol partial ether carboxylates and cyclic ketones.

[0123] (High fluorine content polymer) The high-fluorine content polymer (hereinafter also referred to as "polymer (F)") is a polymer having a higher mass content of fluorine atoms than polymer (P). Polymer (F) is contained in the present composition, for example, as a water-repellent additive.

[0124] The fluorine atom content of the polymer (F) is not particularly limited as long as it is larger than that of the polymer (P). The fluorine atom content of the polymer (F) is preferably 1% by mass or more, more preferably 4% by mass or more, and even more preferably 7% by mass or more. The fluorine atom content of the polymer (F) is preferably 60% by mass or less, more preferably 40% by mass or less. The fluorine atom content (% by mass) of the polymer is 13 The polymer structure can be determined by C-NMR spectroscopy or the like, and the amount can be calculated from the structure.

[0125] When the composition contains polymer (F), the content of polymer (F) in the composition is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of polymer (P). The content of polymer (F) is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of polymer (P).

[0126] (Other optional ingredients) The present composition may further contain components other than the polymer (P), radiation-sensitive acid generator, solvent, and polymer (F) (hereinafter also referred to as "other optional components"). Examples of the other optional components include surfactants, alicyclic skeleton-containing compounds (e.g., 1-adamantanecarboxylic acid, 2-adamantanone, t-butyl deoxycholate, etc.), sensitizers, and uneven distribution promoters. The content of the other optional components can be appropriately set depending on each compound, within a range that does not impair the effects of the present disclosure.

[0127] <Method for producing radiation-sensitive composition> The composition can be produced, for example, by mixing the polymer (P), the radiation-sensitive acid generator, and optionally other components such as a solvent in the desired ratio, and filtering the resulting mixture, preferably using a filter (e.g., a filter with a pore size of about 0.2 μm). The solids concentration of the composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. The solids concentration of the composition is preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 5% by mass or less. By setting the solids concentration of the composition within the above range, good coatability can be achieved, which is advantageous in that a good resist pattern shape can be obtained.

[0128] The composition thus obtained can be used as a positive pattern-forming composition for forming a pattern using an alkaline developer, or as a negative pattern-forming composition for forming a pattern using a developer containing an organic solvent.

[0129] <Polymer> According to the present disclosure, in the above formula (1), Y 1 is expressed by the following formula (2-1): [ka] (In formula (2-1), Ar 1 is a divalent aromatic ring group. 2 is a single bond or a divalent aromatic ring group. 1 is a divalent linking group. n is 0 or 1. 1 " represents a bond to the carbonyl group in formula (1). "*" represents a bond.) is a divalent group represented by R 1 is a divalent hydrocarbon group, and M + has a partial structure which is a sulfonium cation or an iodonium cation, and the partial structure represented by the above formula (1) has two or more iodine atoms (hereinafter also referred to as "polymer P1").

[0130] According to the present disclosure, in the above formula (1), Y 1is expressed by the following formula (2-2): [ka] (In formula (2-2), Ar 3 is a monovalent aromatic ring group. 2 is a divalent linking group. 1 " represents a bond to the carbonyl group in formula (1). "*" represents a bond.) is a divalent group represented by R 1 is a divalent hydrocarbon group, and M + is a sulfonium cation or an iodonium cation (hereinafter also referred to as "polymer P2"). These polymers P1 and P2 are suitable as polymer components (particularly base resins) of radiation-sensitive compositions used in resist pattern formation.

[0131] ≪Compound≫ According to the present disclosure, there is provided a compound represented by the following formula (3-1) (hereinafter also referred to as "compound (3-1)"). [ka] (In formula (3-1), R 2 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond or * 3 -CO-O-. 3 " is R 2 represents the bond to the carbon atom to which Ar is attached. 1 is a divalent aromatic ring group. 2 is a single bond or a divalent aromatic ring group. 1 is a divalent linking group. n is 0 or 1. R 1 is a divalent hydrocarbon group. + is a sulfonium cation or an iodonium cation, provided that formula (3-1) has two or more iodine atoms.

[0132] The present disclosure also provides a compound represented by the following formula (3-2) (hereinafter also referred to as "compound (3-2)"). [ka] (In formula (3-2), R 2 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond or * 3 -CO-O-. 3 " is R 2 represents the bond to the carbon atom to which Ar is attached. 3 is a monovalent aromatic ring group. 2 is a divalent linking group. 1 is a divalent hydrocarbon group. + is a sulfonium cation or an iodonium cation.

[0133] These compounds (3-1) and (3-2) are suitable as monomers constituting the polymer component (particularly the base resin) of the radiation-sensitive composition used in forming a resist pattern. The synthesis method of compounds (3-1) and (3-2) is not particularly limited, and they can be produced by appropriately combining standard methods in organic chemistry. An example of the synthesis method of compound (3-1) is a method in which "CH2=CR 2 -A 1 -Ar 1 -(X 1 -Ar 2 ) n a compound having a partial structure corresponding to -R )-COO-" in the above formula (3-1) 1 -CF2-SO3 - The compound represented by formula (3-1) can be obtained by reacting a compound consisting of an anion having a partial structure corresponding to the formula (3-1) and a cation (e.g., an ammonium cation) in an appropriate solvent, if necessary in the presence of a catalyst, to obtain an intermediate product, and then reacting the obtained intermediate product with a sulfonium halide or iodonium halide that provides an onium cation moiety. However, the synthesis methods for compounds (3-1) and (3-2) are not limited to those described above.

[0134] <Method for forming a resist pattern> The method for forming a resist pattern according to the present disclosure includes a step of applying the present composition to one surface of a substrate (hereinafter also referred to as the "coating step"), a step of exposing the resist film obtained by the coating step (hereinafter also referred to as the "exposure step"), and a step of developing the resist film exposed by the exposure step (hereinafter also referred to as the "developing step"). Examples of patterns formed by the method for forming a resist pattern according to the present disclosure include line and space patterns and hole patterns. The method for forming a resist pattern according to the present disclosure uses the present composition to form a resist film, and therefore can form a resist pattern with good sensitivity and CDU performance and few development defects. Each step will be described below.

[0135] [Coating process] In the coating process, the composition is applied to one side of a substrate to form a resist film on the substrate. Conventional substrates for forming the resist film can be used, including silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective coating, such as that disclosed in JP-A-59-93448, may be formed on the substrate. Examples of methods for applying the composition include spin coating, casting, and roll coating. After coating, a soft bake (hereinafter also referred to as "SB") may be performed to volatilize the solvent in the coating. The SB temperature is preferably 60°C or higher, more preferably 80°C or higher. The SB temperature is preferably 140°C or lower, more preferably 120°C or lower. The SB time is preferably 5 seconds or longer, more preferably 10 seconds or longer. The SB time is preferably 600 seconds or shorter, more preferably 300 seconds or shorter. The average thickness of the resist film formed is preferably 10 to 1,000 nm, more preferably 20 to 500 nm. Soft baking is also called pre-baking.

[0136] [Exposure process] In the exposure step, the resist film obtained in the coating step is exposed. This exposure is carried out by irradiating the resist film with radiation through a photomask, and optionally 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, the radiation irradiated onto the resist film formed using the composition is preferably far ultraviolet light, EUV, or electron beams, more preferably ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV, or electron beams, even more preferably ArF excimer laser light, EUV, or electron beams, even more preferably EUV or electron beams, and particularly preferably EUV.

[0137] After the exposure, post-exposure baking (PEB) is preferably performed to promote dissociation of acid-dissociable groups in the exposed portions of the resist film by the acid generated from a compound that generates acid upon exposure (such as a radiation-sensitive acid generator). This PEB can increase the difference in solubility in a developer between the exposed and unexposed portions. The PEB temperature is preferably 50°C or higher, more preferably 80°C or higher. The PEB temperature is preferably 180°C or lower, more preferably 130°C or lower. The PEB time is preferably 5 seconds or longer, more preferably 10 seconds or longer. The PEB time is preferably 600 seconds or shorter, more preferably 300 seconds or shorter.

[0138] [Development process] In the development step, the exposed resist film is developed, thereby forming a desired resist pattern. 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.

[0139] In the case of alkaline development, examples of the developer used for development include an alkaline aqueous solution containing at least one alkaline compound 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 (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, a TMAH aqueous solution is preferred, with a 2.38% by weight TMAH aqueous solution being more preferred. In the case of organic solvent development, examples of the developer include one or more organic solvents such as hydrocarbons, ethers, esters, ketones, and alcohols, as well as solvents containing the above organic solvents.

[0140] Examples of development methods include a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which a developer is piled up on the surface of the substrate by surface tension and left to stand for a certain period of time (puddle method), a method in which a developer is sprayed onto the surface of the substrate (spray method), and a method in which a developer is continuously dispensed onto a substrate rotating at a constant speed while a developer dispensing nozzle is scanned at a constant speed (dynamic dispense method). [Example]

[0141] The present invention will be specifically described below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. In the following examples, "parts" and "%" are by mass unless otherwise specified.

[0142] <Synthesis of Radiation-Sensitive Acid Generator> [Synthesis Example A1: Synthesis of Compound (A-1)] Compound (A-1) was synthesized according to the following reaction scheme. [ka]

[0143] Compound (PA-1) (20 mmol), compound (PC-1) (20 mmol), methylene chloride (50 mL), and water (50 mL) were added to a recovery flask and stirred at room temperature for 3 hours. The organic layer was washed three times with water, then dried over sodium sulfate and filtered. The solvent was evaporated to obtain compound (A-1).

[0144] [Synthesis Examples A2 to A12: Synthesis of Compounds (A-2) to (A-12)] By appropriately selecting precursors and using the same formulation as in Synthesis Example A1, radiation-sensitive acid generators (compounds (A-2) to (A-12)) represented by the following formulas (A-1) to (A-12) were synthesized. [ka]

[0145] <Synthesis of Radiation-Sensitive Acid Generator Monomer> [Synthesis Example B1: Synthesis of Compound (B-1)] Compound (B-1) was synthesized according to the following reaction scheme. [ka]

[0146] Compound (PB-1) (84 mmol) and acetonitrile (70 mL) were added to a recovery flask, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (84 mmol) was further added and cooled on ice. Compound (PBB-1) (100 mmol) and 4-dimethylaminopyridine (17 mmol) were added and stirred at room temperature. Methylene chloride (180 mL) was added, followed by washing with 2 mol / L aqueous hydrochloric acid and ultrapure water. Ultrapure water (200 mL) and (MC-1) (84 mmol) were added and stirred at room temperature for 2 hours. The organic layer was washed three times with water, dried over sodium sulfate, and filtered. The solvent was evaporated, and the mixture was purified by silica gel column chromatography to obtain compound (B-1).

[0147] [Synthesis Examples B2 to B13: Synthesis of Compounds (B-2) to (B-13)] By appropriately selecting precursors and selecting the same formulation as in Synthesis Example B1, radiation-sensitive acid generator monomers (compounds (B-2) to (B-13)) represented by the following formulas (B-1) to (B-13) were synthesized. [ka] [ka]

[0148] <Polymer synthesis> The methods for measuring the weight average molecular weight (Mw) and number average molecular weight (Mn) of a polymer are shown below. [Mw and Mn] The Mw and Mn of the polymer were measured by gel permeation chromatography (GPC) using GPC columns manufactured by Tosoh Corporation (two "SuperAW2500", one "SuperAW3000", and one "SuperAW4000") under the following conditions. Eluent: tetrahydrofuran (Fujifilm Wako Pure Chemical Industries, Ltd.) Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40℃ Detector: differential refractometer Standard material: monodisperse polystyrene

[0149] [Synthesis Examples P1 to P24] Synthesis of polymers (P-1) to (P-23) and (Pc-1) The copolymerization reaction of the monomers was carried out in a tetrahydrofuran (THF) solvent. The product was crystallized in methanol and repeatedly washed with hexane. After isolation and drying, polymers (P-1) to (P-23) and (Pc-1) with the compositions shown below were obtained. The compositions of the resulting polymers were as follows: 1The polymers were confirmed by H-NMR, and the Mw and dispersity (Mw / Mn) were determined under the GPC conditions described above. The composition, Mw, and dispersity of each monomer in the polymers obtained in each synthesis example are shown in Table 1. The abbreviations for each monomer are as follows:

[0150] (Abbreviation for monomer) [ka]

[0151] [Table 1]

[0152] <Preparation of Radiation-Sensitive Composition> Radiation-sensitive compositions were prepared using the polymers obtained in Synthesis Examples P1 to P24, the radiation-sensitive acid generators obtained in Synthesis Examples A1 to A12, as well as an acid diffusion controller and a solvent. The acid diffusion controllers and solvents used in the preparation of the radiation-sensitive compositions are shown below.

[0153] (acid diffusion control agent) Compounds (D-1) to (D-8): Compounds represented by the following formulas (D-1) to (D-8) [ka]

[0154] (solvent) PGMEA: Propylene glycol monomethyl ether acetate GBL: gamma-butyrolactone CHN: Cyclohexanone PGME: Propylene glycol monomethyl ether DAA: Diacetone alcohol EL: Ethyl lactate HBM: methyl 2-hydroxyisobutyrate

[0155] [Example 1] A mixture of 100 parts by mass of polymer (P-1), 7.5 parts by mass of compound (A-1) as a radiation-sensitive acid generator, 43 mol % of compound (D-8) as an acid diffusion controller based on the total of the anions of polymer (P-1) and compound (A-1), 5,500 parts by mass of PGMEA as a solvent, and 1,500 parts by mass of DAA was used. The mixture was filtered through a membrane filter with a pore size of 0.2 μm to prepare radiation-sensitive composition (R-1).

[0156] [Examples 2 to 53 and Comparative Examples 1 to 6] Radiation-sensitive compositions (R-2) to (R-53) and (CR-1) to (CR-6) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Tables 2 and 3 were used.

[0157] [Table 2]

[0158] [Table 3]

[0159] <Formation of Resist Pattern> Each radiation-sensitive composition was applied to the surface of a 12-inch silicon wafer with a 20-nm-thick underlayer film (AL412, Brewer Science) using a spin coater (CLEAN TRACK ACT12, Tokyo Electron). After soft baking (SB) at 100°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a 35-nm-thick resist film. The resist film was then irradiated with EUV light using an EUV exposure system (model "NXE3300," ASML, NA = 0.33, illumination conditions: Conventional s = 0.89). After EUV light exposure, the resist film was post-exposure baked at 100°C for 60 seconds. The wafer was then developed using a 2.38% by mass aqueous TMAH solution at 23°C for 30 seconds to form a positive-tone 50-nm-pitch, 25-nm-thick contact hole pattern.

[0160] <Evaluation> The resist patterns formed by the above method were measured according to the following methods to evaluate the sensitivity, CDU performance, and development defect suppression of each radiation-sensitive composition. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the resist patterns. The evaluation results are shown in Tables 4 and 5.

[0161] [sensitivity] In forming the resist pattern, the exposure dose for forming a 25 nm contact hole pattern was set as the optimum exposure dose, and this optimum exposure dose was used as the sensitivity (mJ / cm 2 The smaller the value, the better the sensitivity. 2 Less than "A" (very good), 48mJ / cm 2 More than 51mJ / cm 2 The following cases are classified as "B" (good), 51 mJ / cm 2 If the value exceeded this, it was judged as "C" (poor).

[0162] [CDU performance] Using the scanning electron microscope described above, a 25 nm contact hole pattern was observed from above, and a total of 800 lengths were measured at random points. The dimensional variation (3σ) was calculated and used as CDU (nm). The smaller the CDU value, the smaller the long-period hole diameter variation (i.e., the diameter variation between different holes) and the better the CDU performance. CDU of less than 3.4 nm was rated "A" (very good), 3.4 nm to 3.6 nm was rated "B" (good), and 3.6 nm or greater was rated "C" (poor).

[0163] [Development defect suppression] The resist film was exposed to the optimum exposure dose and developed to form a 25-nm contact hole pattern. The number of defects on the wafer was measured using a defect inspection system (KLA-Tencor's "KLA2810"). The observed defects were classified into those judged to be originating from the resist film and those due to foreign matter originating from the external environment. In the evaluation of development defects, if the number of defects judged to be originating from the resist film was less than 35, it was judged as "A" (very good); if it was 35 to 60, it was judged as "B" (good); and if it was more than 60, it was judged as "C" (poor).

[0164] [Table 4]

[0165] [Table 5]

[0166] As shown in Tables 4 and 5, the radiation-sensitive compositions of Examples 1 to 53 all exhibited well-balanced improvements in sensitivity, CDU performance, and development defect suppression. In contrast, the radiation-sensitive compositions of Comparative Examples 1 and 2, in which a polymer not having a specific partial structure was used instead of the polymer (P) having a specific partial structure, were evaluated as C (poor) in sensitivity and development defect suppression. The radiation-sensitive composition of Comparative Example 2, in which no acid generator was blended, also exhibited C (poor) in CDU performance. Furthermore, the radiation-sensitive compositions of Comparative Examples 3 to 6, which contained a polymer (P) having a specific partial structure but did not satisfy any of Requirements 1 to 3, were evaluated as C (poor) in one or more of sensitivity, CDU performance, and development defect suppression.

[0167] From the above results, it can be said that the radiation-sensitive composition and method for forming a resist pattern of the present invention can improve sensitivity, CDU performance, and suppression of development defects in a well-balanced manner. Therefore, the radiation-sensitive composition and method for forming a resist pattern of the present invention are suitable for forming fine resist patterns in the lithography processes of various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. The following formula (1): 【Chemical 1】 [In formula (1), Y １ is represented by the following formula (2-1) or formula (2-2): 【Chemistry 2】 (In formula (2-1) and formula (2-2), Ar １ is a divalent aromatic ring group. ２ is a single bond or a divalent aromatic ring group. ３ is a monovalent aromatic ring group. １ and X ２ are each independently a divalent linking group. n is 0 or 1. １ " represents a bond to the carbonyl group in formula (1). "*" represents a bond.) R is a divalent group represented by the formula: １ is a divalent hydrocarbon group. ＋ is a sulfonium cation or an iodonium cation. "*" represents a bond.] a polymer having a partial structure represented by a radiation-sensitive acid generator; Contains A radiation-sensitive composition that satisfies one or more of the following requirements 1, 2, and 3: Requirement 1: The partial structure represented by the above formula (1) has two or more iodine atoms. Requirement 2: The radiation-sensitive acid generator contains an onium salt having two or more iodine atoms. Requirement 3: The partial structure represented by the above formula (1) contains an iodine atom, and the radiation-sensitive acid generator contains an onium salt containing an iodine atom.

2. The radiation-sensitive composition according to claim 1 , wherein the polymer comprises a structural unit (I) having a partial structure represented by the above formula (1).

3. The radiation-sensitive composition according to claim 2 , wherein the structural unit (I) is represented by the following formula (3): 【Chemistry 3】 (In formula (3), R ２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a single bond or * ２ -CO-O-("* ２ " represents a bond to the main chain). １ , R １ and M ＋ has the same meaning as the above formula (1).

4. 2. The radiation-sensitive composition according to claim 1, wherein an iodine atom contained in at least one member selected from the group consisting of the partial structure represented by formula (1) and the radiation-sensitive acid generator is bonded to an aromatic ring.

5. The radiation-sensitive composition according to claim 1 , wherein the polymer further comprises a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring.

6. The radiation-sensitive composition according to claim 1 , wherein the polymer further comprises a structural unit having an acid-dissociable group.

7. The radiation-sensitive composition according to claim 1 , comprising a photodecomposable base as the radiation-sensitive acid generator.

8. forming a resist film on a substrate using the radiation-sensitive composition according to any one of claims 1 to 7; exposing the resist film to light; developing the exposed resist film; A method for forming a resist pattern, comprising:

9. The following formula (1): 【Chemistry 4】 [In formula (1), Y １ is expressed by the following formula (2-1): 【Chemistry 5】 (In formula (2-1), Ar １ is a divalent aromatic ring group. ２ represents a single bond or a divalent aromatic ring group. １ is a divalent linking group. n is 0 or 1. １ " represents a bond to the carbonyl group in formula (1). "*" represents a bond.) R is a divalent group represented by the formula: １ is a divalent hydrocarbon group. ＋ is a sulfonium cation or an iodonium cation. "*" represents a bond.] and the partial structure represented by formula (1) has two or more iodine atoms.

10. The following formula (1): 【Chemistry 6】 [In formula (1), Y １ is expressed by the following formula (2-2): 【Chemistry 7】 (In formula (2-2), Ar ３ is a monovalent aromatic ring group. ２ is a divalent linking group. １ " represents a bond to the carbonyl group in formula (1). "*" represents a bond.) R is a divalent group represented by the formula: １ is a divalent hydrocarbon group. ＋ is a sulfonium cation or an iodonium cation. "*" represents a bond.] A polymer having a partial structure represented by the following formula:

11. A compound represented by the following formula (3-1): 【Chemistry 8】 (In formula (3-1), R ２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a single bond or * ３ -CO-O-. ３ " is R ２ represents a bond to the carbon atom to which Ar is attached. １ is a divalent aromatic ring group. ２ represents a single bond or a divalent aromatic ring group. １ is a divalent linking group. n is 0 or 1. R １ is a divalent hydrocarbon group. ＋ is a sulfonium cation or an iodonium cation, provided that formula (3-1) has two or more iodine atoms.

12. A compound represented by the following formula (3-2): 【Chemistry 9】 (In formula (3-2), R ２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a single bond or * ３ -CO-O-. ３ " is R ２ represents a bond to the carbon atom to which Ar is attached. ３ is a monovalent aromatic ring group. ２ is a divalent linking group. １ is a divalent hydrocarbon group. ＋ is a sulfonium cation or an iodonium cation.

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