Radiation-sensitive composition, resist pattern forming method, radiation-sensitive acid generator, and compound

Abstract

This radiation-sensitive composition comprises a polymer having an acid dissociable group and a compound represented by formula (1). In formula (1), X1 is *1-SO2-NH- or *1-NH-SO2-. *1 denotes an atomic bond with R1. With respect to R1 and A1, R1 is a monovalent organic group and A1 is a divalent organic group, or alternatively, R1 and A1 are combined with each other to form a group having a ring structure that contains -SO2-NH- in the ring skeleton. M+ is a substituted or unsubstituted iodonium cation or a sulfonium cation that has at least one group selected from the group consisting of a fluoro group, a bromo group, an iodo group, a haloalkyl group, a cyano group, a carbonyl group and a sulfonyl group. However, in cases where M+ is an unsubstituted iodonium cation, A1 has an aromatic ring.

Description

Radiation-sensitive composition, method for forming resist pattern, radiation-sensitive acid generator and compound

[0001] [Cross-Reference to Related Applications] This application claims priority to Japanese Patent Application No. 2024-152724, filed on September 4, 2024, the entire contents of which are incorporated herein by reference. The present disclosure relates to a radiation-sensitive composition, a method for forming a resist pattern, and a radiation-sensitive acid generator and compound.

[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, and a chemical reaction involving this acid causes a difference in the dissolution rate in a developer between the exposed area and the unexposed area, thereby forming a resist pattern on a substrate.

[0003] Further miniaturization of various electronic device structures is rapidly progressing, and accordingly, further miniaturization of resist patterns in lithography processes is required. Furthermore, in response to the demand for further miniaturization of resist patterns, various efforts have been made to improve the resolution of radiation-sensitive compositions used in microfabrication by lithography and the shape of resist patterns (see, for example, Patent Document 1). Patent Document 1 discloses that a radiation-sensitive composition contains an onium salt comprising a radiation-sensitive onium cation having two or more substituents of at least one type selected from the group consisting of a fluoroalkyl group and a fluoro group, and an organic anion having an iodine group, to form a resist pattern.

[0004] International Publication No. 2022 / 130869

[0005] It is believed that the sensitivity to radiation can be improved by introducing a radiation-sensitive cation having a halogen atom or an electron-withdrawing group into the radiation-sensitive acid generator contained in the radiation-sensitive composition. Examples of the electron-withdrawing group include a halogen atom (i.e., a halogeno group) and, for example, a cyano group. Examples of the radiation-sensitive cation having a halogen atom or an electron-withdrawing group include an iodonium cation and a sulfonium cation having an electron-withdrawing group.

[0006] However, when a radiation-sensitive cation having a halogen atom or an electron-withdrawing group is contained in a radiation-sensitive composition, acid may be easily generated, and the storage stability of the radiation-sensitive composition may be reduced. Furthermore, with the recent demand for further miniaturization of resist patterns, it is required to be able to form resist patterns with good CDU (Critical Dimension Uniformity).

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and has as its object to provide a radiation-sensitive composition that exhibits excellent sensitivity and CDU performance while ensuring storage stability, and a method for forming a resist pattern using the radiation-sensitive composition. Another object is to provide an onium salt compound that can provide a radiation-sensitive composition that exhibits excellent storage stability, sensitivity, and CDU performance.

[0008] According to one aspect of the present disclosure, there is provided a radiation-sensitive composition containing a polymer having an acid-dissociable group and a compound represented by the following formula (1): (In formula (1), X １ teeth* １ -SO ２ -NH- or * １ -NH-SO ２ - is. １ is R １ Represents a bond with R. １ and A １ is R １ is a monovalent organic group, and A １ is a divalent organic group, or R １ and A １ are aligned together -SO２ represents a group having a ring structure containing —NH— in the ring skeleton. ＋ is a substituted or unsubstituted iodonium cation, or a sulfonium cation having at least one group selected from the group consisting of a fluoro group, a bromo group, an iodo group, a haloalkyl group, a cyano group, a carbonyl group, and a sulfonyl group, provided that M ＋ is an unsubstituted iodonium cation, A １ has an aromatic ring.)

[0009] According to another aspect of the present disclosure, there is provided a method for forming a resist pattern, the method including the steps of forming a resist film on a substrate using the radiation-sensitive composition described above, exposing the resist film to light, and developing the exposed resist film.

[0010] According to another aspect of the present disclosure, there is provided a radiation-sensitive acid generator represented by the following formula (1B): Also, according to another aspect of the present disclosure, there is provided a compound represented by the following formula (1B): (In formula (1B), X １ teeth* １ -SO ２ -NH- or * １ -NH-SO ２ - is. １ is R １ Represents a bond with R. １ and A ２ is R １ is a monovalent organic group, and A ２ is a divalent organic group having an aromatic ring, or R １ and A ２ are aligned together -SO ２ represents a group having a ring containing —NH— in the ring skeleton and an aromatic ring. ＋ is a substituted or unsubstituted iodonium cation, or a sulfonium cation having at least one group selected from the group consisting of a fluoro group, a bromo group, an iodo group, a haloalkyl group, a cyano group, a carbonyl group, and a sulfonyl group.

[0011] According to the present disclosure, a radiation-sensitive composition having excellent sensitivity and CDU performance while ensuring storage stability can be obtained. Furthermore, according to the present disclosure, by using the radiation-sensitive composition, a resist pattern having a sufficiently small CDU can be obtained.

[0012] Matters relating to the embodiments will be described in detail below. In this specification, a numerical range described using "to" means that the numerical values ​​before and after "to" are included as the lower and upper limits.

[0013] 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 "organic group" refers to an atomic group formed by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound). The term "aromatic ring" encompasses aromatic hydrocarbon rings and aromatic heterocycles. The term "aliphatic hydrocarbon group" encompasses chain hydrocarbon groups and alicyclic hydrocarbon groups.

[0014] 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."

[0015] The expression "substituted or unsubstituted p-valent hydrocarbon group (where p is an integer of 1 or more)" 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.

[0016] <Radiation-Sensitive Composition> The radiation-sensitive composition of the present disclosure (hereinafter also referred to as "the composition") contains a polymer having an acid-dissociable group and a compound represented by the above formula (1). Hereinafter, the polymer having an acid-dissociable group will also be referred to as "polymer (P)," and the compound represented by the above formula (1) will also be referred to as "compound (A)." The components contained in the composition and the components that may be optionally blended will be specifically described below. Note that, unless otherwise specified, each component contained in the composition may be used alone or in combination of two or more.

[0017] <Polymer (P)> The acid-dissociable group of the polymer (P) is a group that substitutes a hydrogen atom of an acidic group such as a carboxyl group or a hydroxyl group, and is a group that dissociates under the action of an acid. When the composition is exposed to light, the acid-dissociable group of the polymer (P) dissociates due to the acid generated by the exposure, generating an acidic group. This can change the solubility of the polymer component in the developer in the exposed portion of the composition. As a result, the composition can be endowed with good lithography properties. In order to sufficiently increase the difference in dissolution rate between the exposed portion and the unexposed portion in the developer, it is preferable that the polymer (P) contains a structural unit having an acid-dissociable group. Hereinafter, the structural unit having an acid-dissociable group contained in the polymer (P) is also referred to as the "first structural unit."

[0018] (First structural unit) The first structural unit is not particularly limited as long as it has an acid-dissociable group. Examples of the first structural unit include a structural unit represented by the following formula (2-1) (hereinafter also referred to as "structural unit (1A)"), a structural unit represented by the following formula (2-2) (hereinafter also referred to as "structural unit (1B)"), and a structural unit represented by the following formula (2-3) (hereinafter also referred to as "structural unit (1C)"): (In formula (2-1), R ３０ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ３ R is a divalent chain organic group or an alicyclic hydrocarbon group. ３１ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３２ and R ３３ are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic heterocyclic group, or R ３２ and R ３３ are combined together to form R ３２ and R ３３ represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which R is bonded. ３１ When is a hydrogen atom, R ３２ and R ３３or both of which are, independently of each other, a substituted or unsubstituted monovalent alicyclic unsaturated hydrocarbon group, a substituted or unsubstituted monovalent aromatic hydrocarbon group, or a monovalent aromatic heterocyclic group, or R ３２ and R ３３ are combined together to form R ３２ and R ３３ represents an alicyclic unsaturated hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which it is bonded. g1 is 0 or 1. In formula (2-2), R ３０ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ４ represents a single bond, -O-, -CO-, * ２ -COO- or * ２ -CONH-. ２ " represents a bond to the main chain. ３４ , R ３５ and R ３６ 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. ２８ is a monovalent substituent. g2 is an integer of 0 to 4. In formula (2-3), R ３０ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ５ represents a single bond, -O-, -CO-, * ３ -COO- or * ３ -CONH-. ３ " represents a bond to the main chain. ３７ R 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. ３８ and R ３９ 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 ３８ and R ３９ are aligned with each other and R ３８ and R ３９ represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms formed together with the carbon atom to which R is bonded.２９ is a monovalent substituent. g3 is an integer of 0 to 4.

[0019] In the above formula (2-1), R ３０ In view of the copolymerizability of the monomer that gives the structural unit (1A), R is preferably a hydrogen atom or a methyl group, and more preferably a methyl group. ３０ is preferably a hydrogen atom from the viewpoint of copolymerizability of the monomer that gives the structural unit (1B). ３０ is preferably a hydrogen atom or a methyl group. ４ Or L in formula (2-3) ５ is preferably a single bond, —COO— or —CONH—.

[0020] L in the above formula (2-1) ３ The divalent chain organic group represented by the formula (I) includes a divalent saturated chain hydrocarbon group having 1 to 20 carbon atoms, a divalent saturated chain hydrocarbon group in which a methylene group is a heteroatom-containing group (for example, -O-, -S-, -CO-, -COO-, -NH-, -NHCO-, -SO ２ Examples of such a divalent group include a divalent group having 2 to 20 carbon atoms substituted with a substituted aryl group (-). The divalent saturated chain hydrocarbon group having 1 to 20 carbon atoms may be linear or branched.

[0021] R in the above formulas (2-1) to (2-3) ３１ ~R ３３ , R ３４ ~R ３６ or R ３７ ~R ３９ 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.

[0022] 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. ３１The monovalent chain hydrocarbon group having 1 to 20 carbon atoms, represented by the formula (I) or (II), is preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms.

[0023] 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 alicyclic saturated 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, an indenyl group, and an indanyl group.

[0024] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, mesityl, vinylphenyl, naphthyl, methylnaphthyl, anthryl, and methylanthryl; and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl. Examples of the monovalent aromatic heterocyclic group include furyl and thienyl.

[0025] R ３２ and R ３３ are combined together to form R ３２ and R ３３ an alicyclic hydrocarbon structure having 3 to 20 carbon atoms formed together with the carbon atom to which R is bonded, and ３８ and R ３９ are combined together to form R ３８ and R ３９ 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 saturated alicyclic structures such as a cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cycloheptane structure, and cyclooctane structure; monocyclic unsaturated alicyclic structures such as cyclopentene and cyclohexene; and polycyclic alicyclic structures such as a norbornane structure, adamantane structure, tricyclodecane structure, and tetracyclododecane structure.

[0026] R３１ , R ３５ , R ３６ , R ３７ , R ３８ or R ３９ Examples of the monovalent oxyhydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include the above-mentioned R ３１ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include groups having an oxygen atom at the bond-side terminal of the groups exemplified as R ３４ Of these, the monovalent oxyhydrocarbon group represented by the following formula (I) is preferably an alkoxy group, a cycloalkoxy group, or a cycloalkylalkoxy group.

[0027] R ３１ ~R ３９ When the group represented by R has a substituent, examples of the substituent include a halogeno group (a fluoro group, a chloro group, a bromo group, an iodo group, etc.), a hydroxyl group, an alkoxy group having 1 to 3 carbon atoms, etc. ２８ or R ２９ Examples of the monovalent substituent represented by the formula (I) include a halogeno group (such as a fluoro group, a chloro group, a bromo group, or an iodo group), a substituted or unsubstituted monovalent hydrocarbon group, a substituted or unsubstituted monovalent oxyhydrocarbon group, an ester group (-COOR, where R is an alkyl group having 1 to 3 carbon atoms), an alkylsulfonyl group, a cycloalkylsulfonyl group, a hydroxyl group, a carboxy group, a cyano group, and a nitro group. When one or more hydrogen atoms of the monovalent hydrocarbon group or the monovalent oxyhydrocarbon group are substituted, examples of the substituent include a halogeno group, a hydroxyl group, a carboxy group, a cyano group, and a nitro group. g1 and g2 are preferably 0 to 2.

[0028] Specific examples of the first structural unit include structural units represented by the following formulas. However, the first structural unit is not limited to the following specific examples. In the following formulas, R ３０ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0029] Structural unit (1A)

[0030] Structural unit (1B)

[0031] Structural unit (1C)

[0032] In the polymer (P), the content of the first structural unit is preferably 30 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more, based on the total structural units constituting the polymer (P). The content of the first structural unit is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 65 mol% or less, based on the total structural units constituting the polymer (P). By setting the content of the first structural unit within the above range, the difference in dissolution rate in a developer between the exposed and unexposed portions can be sufficiently increased, and the pattern shape of the resist film can be improved.

[0033] The polymer (P) may contain structural units (hereinafter also referred to as "other structural units") different from the first structural unit. Examples of the other structural units include the following second structural unit, third structural unit, fourth structural unit, and fifth structural unit.

[0034] (Second structural unit) The polymer (P) may further contain a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring (referred to as the "second structural unit"). When the polymer (P) has a hydroxyl group bonded to the aromatic ring, the CDU performance and LWR (Line Width Roughness) performance of the composition can be further improved, and the effect of suppressing dissolution of unexposed areas into a developer can be highly effective, thereby sufficiently reducing defects. Furthermore, the polymer (P) containing the second structural unit can be preferably used in pattern formation using exposure to radiation with a wavelength of 50 nm or less, particularly electron beams or EUV.

[0035] The second structural unit differs from the first structural unit in that it does not have an acid-dissociable group. In this specification, a structural unit having a partial structure in which a hydroxyl group and an acid-dissociable group are bonded to the same aromatic ring is classified as a first structural unit. When the polymer (P) contains the second structural unit, the polymer (P) and the sulfonamide moiety in the compound (A) (X in the above formula (1)) are １It is considered that this contributes to the improvement of the CDU performance and LWR performance of the composition by increasing the interaction with the polymer (P) and shortening the diffusion of the compound (A).

[0036] A preferred example of the second structural unit is a structural unit represented by the following formula (3). (In formula (3), R ５０ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. ２ represents a single bond, —COO—, —CONH—, or —O—. １０ is a group obtained by removing (n1+n2+1) hydrogen atoms from an aromatic ring. ４ is a substituent different from a hydroxyl group and does not have an acid-dissociable group. n1 is an integer of 1 or more. n2 is an integer of 0 or more. When n2 is 2 or more, a plurality of R ４ are the same or different.)

[0037] In the above formula (3), R ５０ is preferably a hydrogen atom or a methyl group from the viewpoint of copolymerizability of the monomer that provides the second structural unit. １０ The aromatic ring contained in A is preferably an aromatic hydrocarbon ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring. １０ The aromatic ring contained in is preferably a benzene ring or a naphthalene ring, more preferably a benzene ring.

[0038] The position of the hydroxyl group bonded to the aromatic ring is not particularly limited. For example, when the second structural unit has a hydroxyl group bonded to a benzene ring, the bonding position of the hydroxyl group on the benzene ring in the second structural unit is not particularly limited. ２ ) may be at any of the ortho, meta and para positions.

[0039] R ４Specific examples of n1 include monovalent hydrocarbon groups, halogeno groups (fluoro, chloro, bromo, iodo, etc.), carboxy groups, ester groups, acyl groups, and monovalent oxyhydrocarbon groups. n1 is preferably 1 to 3, and more preferably 1 or 2. n2 is preferably 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0040] Specific examples of the second structural unit include structural units represented by the following formulae: However, the second structural unit is not limited to these specific examples. (In the formula, R ５０ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group.

[0041] In the polymer (P), the content of the second structural unit is preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more, based on the total amount of structural units contained in the polymer (P). Furthermore, the content of the second structural unit is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 65 mol% or less, based on the total amount of structural units contained in the polymer (P). By setting the content of the second structural unit within the above range, the lithography properties of the composition, such as LWR performance and CDU performance, can be further improved, and defects can be sufficiently reduced.

[0042] (Third Structural Unit) The polymer (P) may further contain a structural unit derived from a radiation-sensitive onium salt (referred to as the "third structural unit"). The third structural unit is typically a structural unit derived from a monomer comprising a radiation-sensitive onium cation and an organic anion. The third structural unit is thought to be formed by the radiation-induced decomposition of the radiation-sensitive onium cation to liberate an organic anion, which then bonds with hydrogen abstracted from components contained in the composition (e.g., a radiation-sensitive acid generator, an acid diffusion controller, a solvent, etc.) to generate an acid derived from the organic anion. Examples of the organic anion include a sulfonate anion, a carboxylate anion, and a sulfonimide anion.

[0043] When the organic anion in the third structural unit is a sulfonate anion or a sulfonimide anion, the third structural unit is thought to function primarily as a radiation-sensitive acid generator by generating a strong acid that induces dissociation of the acid-dissociable group under normal conditions. On the other hand, when the organic anion in the third structural unit is a carboxylate anion, the third structural unit is thought to function primarily as an acid diffusion controller by generating a weak acid that does not induce dissociation of the acid-dissociable group under normal conditions. Here, "normal conditions" refers to conditions in which post-exposure baking (PEB) is performed at 110°C for 60 seconds.

[0044] The third structural unit is typically a structural unit derived from a monomer having a radiation-sensitive onium cation, an organic anion, and a group participating in polymerization. ２ An onium salt consisting of a sulfonate anion having no —NH— and a radiation-sensitive cation is preferably used. The third structural unit is the negatively charged portion of the organic anion (—SO ３ － Ya-COO － ) may be bonded to the main chain of the polymer via a linking group, and the radiation-sensitive onium cation may form a counter ion. Alternatively, the positively charged portion of the radiation-sensitive onium cation may be bonded to the main chain of the polymer via a linking group, and the organic anion may form a counter ion. In order to improve the CDU performance of the present composition, it is preferable that the third structural unit has the negatively charged portion of the organic anion bonded to the main chain of the polymer via a linking group, and the -SO of the sulfonate anion ３ － is more preferably bonded to the main chain of the polymer via a linking group.

[0045] The radiation-sensitive cation in the third structural unit is preferably a sulfonium cation or an iodonium cation, more preferably a triarylsulfonium cation or a diaryliodonium cation, from the viewpoint of enhancing the sensitivity of the present composition. From the viewpoint of further enhancing the sensitivity of the present composition, the aromatic ring (i.e., S ＋ or I ＋Preferably, a total of one or more of an iodo group, a fluoro group (excluding the fluoro group in a fluoroalkyl group), and a fluoroalkyl group are bonded to the aromatic ring bonded to the aromatic ring. The fluoroalkyl group is preferably a trifluoromethyl group.

[0046] Specific examples of the third structural unit include structural units represented by the following formulas: However, the third structural unit is not limited to these specific examples. (In the formula, R ４０ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＋ is a sulfonium cation or an iodonium cation. － is a sulfonate anion or a carboxylate anion.

[0047] When the polymer (P) contains a third structural unit, the content of the third structural unit in the polymer (P) is preferably 1 mol% or more, more preferably 5 mol% or more, based on the total amount of structural units contained in the polymer (P). Also, the content of the third structural unit in the polymer (P) is preferably 30 mol% or less, more preferably 25 mol% or less, based on the total amount of structural units contained in the polymer (P). By setting the content of the third structural unit within the above range, the effect of improving the sensitivity of the composition by introducing the third structural unit can be sufficiently obtained.

[0048] (Fourth Structural Unit) The polymer (P) may further contain a structural unit having a lactone structure, a cyclic carbonate structure, a sultone structure, or a ring structure comprising a combination of two or more of these (excluding those corresponding to the first to third structural units; hereinafter, also referred to as the "fourth structural unit"). By introducing the fourth structural unit into the polymer (P), the solubility in a developer can be adjusted, and as a result, the lithography properties of the composition can be further improved. Furthermore, by including the fourth structural unit in the polymer (P), the adhesion between a resist film obtained using the composition and a substrate can be improved.

[0049] Examples of the fourth structural unit include structural units represented by the following formula:

[0050]

[0051] (In the formula, R Ｌ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0052] When the polymer (P) contains a fourth structural unit, the content of the fourth structural unit is preferably 1 mol% or more, more preferably 3 mol% or more, based on the total structural units constituting the polymer (P). The content of the fourth structural unit is preferably 50 mol% or less, more preferably 30 mol% or less, and even more preferably 15 mol% or less, based on the total structural units constituting the polymer (P). Setting the content of the fourth structural unit within the above range is advantageous in that it can improve the lithography properties of the composition and can improve the adhesion of a resist film obtained using the composition to a substrate.

[0053] (Fifth Structural Unit) The polymer (P) may further contain a structural unit having an alcoholic hydroxyl group (excluding those corresponding to the first to fourth structural units; hereinafter, also referred to as the "fifth structural unit"). Herein, the "alcoholic hydroxyl group" refers to a group having a structure in which a hydroxyl group is directly bonded to a carbon atom constituting an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a chain hydrocarbon group, an alicyclic hydrocarbon group, or may be substituted with a halogen atom or the like, or may be an aliphatic hydrocarbon group constituting a heterocycle (e.g., a methylene group). When the polymer (P) further contains the fifth structural unit, the solubility of the polymer (P) in a developer can be improved, and as a result, the lithography performance of the composition can be further improved.

[0054] Specific examples of the fifth structural unit include structural units represented by the following formulas. (In the formula, R Ｌ２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0055] When the polymer (P) contains the fifth structural unit, the content of the fifth structural unit is preferably 1 mol % or more, more preferably 3 mol % or more, based on all structural units constituting the polymer (P), and the content of the fifth structural unit is preferably 30 mol % or less, more preferably 20 mol % or less, based on all structural units constituting the polymer (P).

[0056] In addition to the above, other structural units contained in the polymer (P) include, for example, 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); structural units containing a non-acid-dissociable hydrocarbon group (specifically, a structural unit derived from styrene or a halogenated styrene (e.g., a styrene unit, a bromostyrene unit, an iodostyrene unit), 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 invention are not impaired. The polymer (P) can be synthesized, for example, by polymerizing monomers that provide each structural unit in an appropriate solvent using a known radical polymerization initiator or the like.

[0057] 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. 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.

[0058] 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. The Mw / Mn of the polymer (P) may be 1.0 or more.

[0059] The polymer (P) is preferably blended into the composition as at least a part of the base resin, and the content of the polymer (P) in the composition is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 85% by mass or more, based on the total amount of solids contained in the composition.

[0060] <Compound (A)> Compound (A) is an onium salt represented by the following formula (1), which generates an acid upon exposure. Compound (A) can function as a radiation-sensitive acid generator in the present composition by generating a strong acid (sulfonic acid) that induces dissociation of an acid-dissociable group under the above-mentioned normal conditions. (In formula (1), X １ teeth* １ -SO ２ -NH- or * １ -NH-SO ２ - is. １ is R １ Represents a bond with R. １ and A １ is R １ is a monovalent organic group, and A １ is a divalent organic group, or R １ and A １ are aligned together -SO ２ represents a group having a ring structure containing —NH— in the ring skeleton. ＋ is a substituted or unsubstituted iodonium cation, or a sulfonium cation having at least one group selected from the group consisting of a fluoro group, a bromo group, an iodo group, a haloalkyl group, a cyano group, a carbonyl group, and a sulfonyl group, provided that M ＋ is an unsubstituted iodonium cation, A １ has an aromatic ring.)

[0061] In an acid generator comprising a sulfonate anion and a radiation-sensitive cation, if the radiation-sensitive cation has a halogen atom or an electron-withdrawing group, the efficiency of acid generation upon irradiation with radiation such as EUV can be increased, and acid can be generated quickly with less energy. This is expected to result in higher sensitivity of the radiation-sensitive composition. Examples of radiation-sensitive cations having a halogen atom include iodonium cations and sulfonium cations having a halogeno group (specifically, one or more functional groups selected from the group consisting of a fluoro group, a bromo group, and an iodo group). Examples of radiation-sensitive cations having an electron-withdrawing group include cations having one or more of a halogeno group, a haloalkyl group, a cyano group, a carbonyl group, and a sulfonyl group.

[0062] On the other hand, it has been found that radiation-sensitive cations having halogen atoms or electron-withdrawing groups have high electrophilicity, and that when a radiation-sensitive cation having a halogen atom or an electron-withdrawing group is introduced into a radiation-sensitive composition, the storage stability of the radiation-sensitive composition is likely to decrease, for example, when it is combined with a component with relatively high basicity (strong base component). Examples of strong base components include the anion moiety of an acid diffusion controller (typical examples are salicylate anion and benzoate anion). In this regard, according to the present disclosure, an acid generator comprising a sulfonate anion and a radiation-sensitive cation having a halogen atom or an electron-withdrawing group is provided with an -SO ２ By introducing --NH--, it is possible to ensure the storage stability of the radiation-sensitive composition while achieving high sensitivity and improved CDU performance.

[0063] In the above formula (1), R １ The monovalent organic group represented by R may be a group having a chain structure or a group having a ring structure. １ The monovalent organic group represented by the formula (I) is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms; a substituted or unsubstituted hydrocarbon group in which a part of the methylene groups is -O-, -CO-, -S-, -NH-, -SO ２ -, -CO-O-, -O-CO-, -NH-CO-, -CO-NH-, -SO ２ -NH- or -NH-SO２ and monovalent groups having 1 to 20 carbon atoms substituted with -. Examples of the monovalent hydrocarbon group include monovalent chain hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms. Specific examples of the monovalent hydrocarbon group include R ３１ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include the same groups as those exemplified above as the monovalent hydrocarbon group having 1 to 20 carbon atoms, represented by the following formula:

[0064] The monovalent group having 1 to 20 carbon atoms in which a portion of the methylene groups contained in a substituted or unsubstituted hydrocarbon group has been replaced with -O- or the like may have a chain structure or a ring structure. Examples of the ring structure include a lactone structure, a cyclic carbonate structure, a sultone structure, a thioxane structure, an acetal ring structure, a cyclic ether structure, a cyclic amide structure, a cyclic imide structure, or a ring structure formed by combining two or more of these. The ring structure may be either a monocyclic structure or a polycyclic structure, and may further be any of a bridged structure, a fused ring structure, and a spiro ring structure.

[0065] A １ The divalent organic group represented by R １ Examples of the monovalent organic group represented by the formula (I) include groups in which one hydrogen atom has been removed from the specific examples of the monovalent organic group represented by the formula (I). １ and A １ But these are combined together to form -SO ２ When representing a group having a ring structure containing --NH-- in the ring skeleton, a specific example thereof is a group having a sulfobenzimidyl structure.

[0066] R １ and A １ When has a substituent, the substituent may be a halogeno group (such as a fluoro group, a chloro group, a bromo group, or an iodo group), 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 (—COOR), or —NH—SO ２ -R, -SO ２Examples of the substituent include -NH-R (wherein R is an alkyl group or haloalkyl group having 1 to 3 carbon atoms), an alkylsulfonyl group, a cycloalkylsulfonyl group, a hydroxy group, a carboxy group, a cyano group, and a nitro group. When one or more hydrogen atoms of an alkyl group, an alkoxy group, a cycloalkyl group, or a cycloalkyloxy group are substituted, examples of the substituent include a halogeno group, a hydroxy group, a carboxy group, a cyano group, and a nitro group.

[0067] A in the above formula (1) is preferred in that it can increase the sensitivity of the compound (A) and lower the acid dissociation constant (pKa) of the sulfonamide moiety in the compound (A). １ Preferably, A has an aromatic ring. １ When A has an aromatic ring, examples of the aromatic ring include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, an indene ring, and a fluorene ring; and aromatic heterocycles such as a pyridine ring, a thiophene ring, and a furan ring. １ The aromatic ring contained in A is preferably a benzene ring or a naphthalene ring, and more preferably a benzene ring. １ The number of benzene rings therein is not particularly limited, but from the viewpoints of ease of synthesis and defect suppression, one or two is more preferred.

[0068] The present composition is characterized by the fact that it is possible to obtain a radiation-sensitive composition having excellent storage stability while increasing the sensitivity of the composition. １ has an aromatic ring, and X in the above formula (1) １ But, A １ directly bonded to an aromatic ring in A １ -O-, -CO-, -S-, -NH-, -SO ２ -, -CO-O-, -O-CO-, -CO-NH- or -NH-CO-, １ It is preferable that the aromatic ring is bonded to the aromatic ring of the formula (I).

[0069] M ＋is a substituted or unsubstituted iodonium cation, or a sulfonium cation having at least one group (hereinafter also referred to as "specific group") selected from the group consisting of a fluoro group, a bromo group, an iodo group, a haloalkyl group, a cyano group, a carbonyl group, and a sulfonyl group. M ＋ is preferably an arylsulfonium cation having a specific group, or a substituted or unsubstituted aryliodonium cation. In the arylsulfonium cation or aryliodonium cation, S ＋ or I ＋ Examples of the aromatic ring bonded to the ring include a benzene ring, a naphthalene ring, an anthracene ring, and a thiophene ring, and among these, a benzene ring or a naphthalene ring is preferred.

[0070] In order to further enhance the sensitivity of the present composition, the specific group in the sulfonium cation is preferably bonded to an aromatic ring. ＋ With regard to the specific group, examples of the haloalkyl group include a group in which any hydrogen atom in a linear or branched alkyl group having 1 to 6 carbon atoms has been replaced with a halogen atom (such as a fluorine atom, a chlorine atom, a bromine atom or an iodine atom). The haloalkyl group preferably has 1 to 3 carbon atoms, and more preferably 1 or 2 carbon atoms.

[0071] M ＋ When M has a carbonyl group as a specific group, ＋ represents a group containing a specific group, such as —CO—R １０ or -CO-O-R １０ It is preferable that M ＋ When M has a sulfonyl group as a specific group, ＋ represents a group containing a specific group, such as —SO ２ -R １０ It is preferable that R １０ is an alkyl group. １０ The number of carbon atoms is preferably 1 to 6, more preferably 1 to 3, and even more preferably 1 or 2.

[0072] M ＋is a sulfonium cation, M ＋ The number of specific groups contained in M ​​(when two or more types are contained, the total number of specific groups) may be one or more per molecule. ＋ is a sulfonium cation, M ＋ The number of specific groups that M has is preferably 2 or more, in order to further increase the sensitivity of the radiation-sensitive composition. ＋ is a sulfonium cation, M ＋ The number of specific groups contained in M ​​is preferably 10 or less, and more preferably 8 or less, from the viewpoint of the balance between the ease of synthesis of the compound and the effect of introducing the specific groups. ＋ When is an iodonium cation, in terms of the sensitivity of the present composition, M ＋ It is preferable that M has one or more specific groups. ＋ is an iodonium cation, M ＋ The number of specific groups that M has is preferably 10 or less, more preferably 8 or less, from the viewpoint of the balance between the ease of synthesis of the compound and the effect of introducing the specific groups. ＋ When is an unsubstituted iodonium cation, A in the above formula (1) １ has an aromatic ring.

[0073] The sensitivity of the composition can be increased. ＋ preferably has at least one functional group (hereinafter also referred to as "specific halo group") selected from the group consisting of a fluoro group (excluding a fluoro group in a fluoroalkyl group), a bromo group, an iodo group, and a fluoroalkyl group, and M ＋ It is more preferable that M has an aromatic ring and the specific halo group is bonded to the aromatic ring. ＋ has preferably an iodo group, more preferably an iodo group bonded to an aromatic ring.

[0074] M ＋ Preferred specific examples of the radiation-sensitive cation represented by the formula (5) include a cation represented by the formula (6) below. (In formula (5), R １ａ and R ２ａare 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. However, a1+a2+a3≧1 is satisfied, and R in formula (5) １ａ , R ２ａ and R ３ａ In formula (6), one or more of R ４ａ and R ５ａ are each independently a monovalent substituent; a4 and a5 are each independently an integer of 0 to 5.

[0075] In the above formulas (5) and (6), R １ａ , R ２ａ , R ３ａ , R ４ａ and R ５ａ Examples of the monovalent substituent represented by the formula (I) include a fluoro group, a chloro group, a bromo group, an iodo group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted cycloalkyloxy group, -CO-R １０ , —CO—O—R １０ , -SO ２ -R １０ , a cycloalkylsulfonyl group, a hydroxy group, a carboxy group, a cyano group, a nitro group, etc. １ａ ~R ５ａ is a group having a substituent, such as a substituted alkyl group or a substituted alkoxy group, examples of the substituent include a fluoro group, a chloro group, a bromo group, an iodo group, a hydroxy group, a carboxy group, a cyano group, a nitro group, and an alkoxy group having 1 to 5 carbon atoms.

[0076] R １ａ and R ２ａ When taken together to connect the rings to which they are attached, R １ａ and R ２ａ is preferably a single bond connecting the rings or forms —O— or —S—.１ａ , a2 R ２ａ and a3 R ３ａ The number of specific groups is 1 or more, preferably 2 or more. ４ａ and a5 R ５ａ It is preferred that at least one of these groups is a specific group.

[0077] R present in formula (5) １ａ , R ２ａ and R ３ａ In the same manner, when at least one of R ４ａ and R ５ａ Preferably, at least one of the following is an iodo group. The molecular weight of compound (A) is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0078] A preferred example of the compound (A) is an onium salt represented by the following formula (1A). (In formula (1A), R ２ and W １ is R ２ is a monovalent organic group, and W １ is a divalent group obtained by removing two hydrogen atoms from the ring portion of a substituted or unsubstituted aromatic ring, or R ２ and W １ are aligned together -SO ２ It represents a condensed ring structure of a heterocycle containing —NH— in the ring skeleton and an aromatic ring. ２ represents a single bond, —O—, —CO—, —S—, —NH—, or —SO ２ -, -CO-O-, -O-CO-, -CO-NH- or -NH-CO-. １ is -O-, -CO-, -S-, -NH-, -SO ２ -, -CO-O-, -O-CO-, -CO-NH-, -NH-CO-, a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted hydrocarbon group in which some of the methylene groups are -O-, -CO-, -S-, -NH-, or -SO ２is a divalent group substituted with -, -CO-O-, -O-CO-, -NH-CO- or -CO-NH-. ｆ１ and R ｆ２ are each independently a hydrogen atom, a fluorine atom, an alkyl group, or a fluoroalkyl group. m1 is an integer of 1 to 4. X １ and M ＋ has the same meaning as the above formula (1).

[0079] In the above formula (1A), R ２ is a monovalent organic group, R １ Examples of the monovalent organic groups include the same groups as those exemplified in the description of W. １ In the divalent group represented by the formula: １ The aromatic ring may be the same as the ring exemplified in the description of the case where R has an aromatic ring. The aromatic ring is preferably a benzene ring. In addition, when the aromatic ring has a substituent, the substituent may be R １ and A １ Examples of the substituent that may be possessed by L include the same groups as those exemplified above. ２ is a single bond, —O—, —CO—, —SO ２ -, -CO-O- or -O-CO- is preferred.

[0080] L １ The divalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (2-1) to the formula (2-3) includes R ３１ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include groups in which one hydrogen atom has been removed from the groups exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms, such as:

[0081] From the viewpoint of ensuring the solubility of the compound (A) in the developer, L １ is -O-, -CO-, -S-, -NH-, -SO ２ -, -CO-O-, -O-CO-, -CO-NH-, -NH-CO-, a substituted or unsubstituted divalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted aliphatic hydrocarbon group in which some of the methylene groups are -O-, -CO-, -S-, -NH-, or -SO ２It is preferably a divalent group substituted with -, -CO-O-, -O-CO-, -NH-CO- or -CO-NH-.

[0082] R ｆ１ or R ｆ２ When is a trifluoroalkyl group, examples of the trifluoroalkyl group include a linear or branched alkyl group having 1 to 10 carbon atoms in which one or more hydrogen atoms have been replaced with a fluorine atom. Specific examples of such a group include a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a pentafluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, and a 1,1,1,3,3,3-hexafluoropropyl group. From the viewpoint of enhancing the sensitivity of the present composition, the fluoroalkyl group is preferably a linear or branched fluoroalkyl group having 1 to 3 carbon atoms, and more preferably a trifluoromethyl group.

[0083] -SO ３ － R on the carbon to which ｆ１ and R ｆ２ is preferably a hydrogen atom, a fluorine atom or a fluoroalkyl group, and more preferably a fluorine atom or a trifluoromethyl group. m1 is preferably 1 to 4, and more preferably 1 or 2.

[0084] Compound (A) is a compound having a group "-X １ -R" (where X １ teeth* ３ -SO ２ -NH- or * ３ -NH-SO ２ - is. ３ represents a bond to R. R is a monovalent organic group. ) may be present in one molecule or may have a plurality of groups "-X １ When there are multiple "-R" groups in one molecule, １ -R" is W in the above formula (1A). １ and L １ and W １ and L １ In the compound (A), the number of groups "-X" per molecule may be １The number of "-R" is preferably 1 to 4, and more preferably 1 or 2, from the viewpoints of storage stability, ease of synthesis, and defect suppression.

[0085] Specific examples of the anion constituting the compound (A) include compounds represented by the following formula:

[0086] Specific examples of the radiation-sensitive cation constituting the compound (A) include cations represented by the following formulas.

[0087] Further specific examples of the compound (A) include onium salts obtained by arbitrarily combining the above-mentioned anions and radiation-sensitive cations, although the compound (A) is not limited to these specific examples.

[0088] In the present composition, the content of compound (A) is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of polymer (P). Furthermore, the content of compound (A) is preferably 45 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less, per 100 parts by mass of polymer (P). By setting the content of compound (A) within the above range, the sensitivity and CDU performance of the present composition can be maintained at a good level, while the storage stability can be improved in a balanced manner.

[0089] <Other Components> The present composition may further contain, in addition to the polymer (P) and the compound (A), a component different from the polymer (P) and the compound (A) (hereinafter also referred to as "other components"). Examples of the other components include a sulfonium salt different from the compound (A) (hereinafter also referred to as "onium salt (B)"), an acid diffusion controller, a high-fluorine-content polymer, a solvent, etc.

[0090] (Onium Salt (B)) The onium salt (B) is —SO ２The compound (A) is composed of a sulfonate anion having no —NH— and a radiation-sensitive cation. Because the compound (A) has a sulfonamide moiety, it is relatively hydrophilic, and it is believed that the high hydrophilicity of the compound (A) may affect the uniformity of the resist pattern. In view of this, by using the compound (A) in combination with the onium salt (B) as a radiation-sensitive acid generator, it is possible to obtain a radiation-sensitive composition with superior lithography performance while ensuring storage stability. The molecular weight of the onium salt (B) is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0091] Specific examples of the onium salt (B) include compounds represented by the following formula (7). (In formula (7), A ２ is -SO ２ It is a monovalent organic group that does not have —NH—. ＋ is a radiation-sensitive cation.

[0092] In the above formula (7), A ２ The monovalent organic group represented by the formula (I) is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms; a substituted or unsubstituted hydrocarbon group in which a part of the methylene groups is -O-, -CO-, -S-, -NH-, -SO ２ Specific examples of the monovalent hydrocarbon group include R in the above formulas (2-1) to (2-3). ３１ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include the same groups as those exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms, represented by the formula: -O-, etc. The monovalent group having 1 to 20 carbon atoms, in which a portion of the methylene groups contained in the substituted or unsubstituted hydrocarbon group are replaced with -O-, etc., may have a chain structure or a ring structure. The ring structure may be either a monocyclic structure or a polycyclic structure, and may also be any of a bridged structure, a fused ring structure, and a spiro ring structure.

[0093] A ２When has a substituent, examples of the substituent include a halogeno group (a fluoro group, a chloro group, a bromo group, an iodo group, etc.), 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 (—COOR), an alkylsulfonyl group, a cycloalkylsulfonyl group, a hydroxy group, a carboxy group, a cyano group, a nitro group, etc. When one or more hydrogen atoms of an alkyl group, an alkoxy group, a cycloalkyl group, or a cycloalkyloxy group are substituted, examples of the substituent include a halogeno group, a hydroxy group, a carboxy group, a cyano group, a nitro group, etc.

[0094] In terms of obtaining a radiation-sensitive composition with higher sensitivity, the sulfonate anion in the onium salt (B) preferably has an iodine group, and more preferably the sulfonate anion in the onium salt (B) has an aromatic ring and an iodine group bonded to the aromatic ring.

[0095] Q ＋ Examples of the radiation-sensitive cation represented by the formula (I) include sulfonium cations, iodonium cations, and quaternary ammonium cations. Q ＋ is preferably a sulfonium cation or an iodonium cation, and more preferably an arylsulfonium cation or an aryliodonium cation. ＋ is preferably a substituted or unsubstituted iodonium cation, or a sulfonium cation having at least one group (i.e., a specific group) selected from the group consisting of a fluoro group, a bromo group, an iodo group, a haloalkyl group, a cyano group, a carbonyl group, and a sulfonyl group. ＋ is a substituted or unsubstituted iodonium cation or a sulfonium cation having a specific group, ＋ Specific examples of the cations include the same cations as those exemplified as the radiation-sensitive cations contained in compound (A).

[0096] Specific examples of the onium salt (B) include onium salts composed of the organic anions shown below and the radiation-sensitive cations or unsubstituted sulfonium cations exemplified in the description of the compound (A), although the onium salt (B) contained in the present composition is not limited to the following:

[0097] When the composition contains an onium salt (B), the content of the onium salt (B) is preferably 1 part by mass or more, and more preferably 2 parts by mass or more, per 100 parts by mass of the polymer (P) in order to further improve the CDU performance of the composition. Furthermore, from the viewpoint of suppressing the occurrence of defects due to the radiation-sensitive acid generator, the content of the onium salt (B) is preferably 25 parts by mass or less, and more preferably 20 parts by mass or less, per 100 parts by mass of the polymer (P).

[0098] When the onium salt (B) is contained in the present composition, the ratio of compound (A) to onium salt (B) is preferably such that the content of compound (A) is 10 to 80 parts by mass per 100 parts by mass of the total amount of compound (A) and onium salt (B). This allows for a radiation-sensitive composition that exhibits excellent sensitivity and CDU performance while ensuring the storage stability of the present composition. The content of compound (A) is more preferably 15 parts by mass or more, and even more preferably 25 parts by mass or more, per 100 parts by mass of the total amount of compound (A) and onium salt (B). The content of compound (A) is more preferably 75 parts by mass or less, and even more preferably 70 parts by mass or less, per 100 parts by mass of the total amount of compound (A) and onium salt (B).

[0099] (Acid Diffusion Controller) The acid diffusion controller is a component that can suppress the diffusion of acid generated in the resist film upon exposure of the present composition within the resist film, thereby suppressing acid-induced chemical reactions in unexposed areas. By incorporating such an acid diffusion controller in the present composition, the CDU performance of the present composition can be further improved. As the acid diffusion controller, an onium salt composed of a carboxylate anion and a radiation-sensitive cation can be preferably used, in terms of high freedom of selection and excellent lithography performance. 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.

[0100] When the acid diffusion controller has a carboxylate anion, specific examples of the acid diffusion controller include compounds represented by the following formula (8). (In formula (8), A ３ is a monovalent organic group. ＋ is a radiation-sensitive cation.

[0101] In the above formula (8), A ３ Specific examples of the monovalent organic group represented by the formula (7) include A ２ Examples of the monovalent organic group represented by U include the same groups as those exemplified in the description of the monovalent organic group represented by U ＋ The radiation-sensitive cation represented by the formula (7) is ＋ Examples of the cations include the same groups as those exemplified in the description of the radiation-sensitive cations represented by the following formula:

[0102] The organic anion (A ３ -COO － Specific examples of the anions include those represented by the following formulas:

[0103] When an acid diffusion controller is blended in 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 sufficiently improving the CDU performance. Furthermore, from the viewpoint of suppressing the occurrence of defects due to the acid diffusion controller, the content of the acid diffusion controller is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, per 100 parts by mass of polymer (P).

[0104] When an acid diffusion controller is incorporated into the composition, the content of the acid diffusion controller in the composition is preferably 5 mol % or more, more preferably 10 mol % or more, and even more preferably 20 mol % or more, based on the total amount of the radiation-sensitive acid generator (specifically, the total amount of compound (A) and onium salt (B)) contained in the composition and the monomer that provides the third structural unit in the polymer (P). Furthermore, the content of the acid diffusion controller is preferably 90 mol % or less, more preferably 80 mol % or less, based on the total amount of the radiation-sensitive acid generator contained in the composition and the monomer that provides the third structural unit in the polymer (P). By setting the content of the acid diffusion controller within the above range, the CDU performance of the composition can be further improved.

[0105] (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 radiation-sensitive composition, for example, as a water-repellent additive or a modifier that improves the lithography performance, etc. of the composition.

[0106] 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 spectrum measurement or the like, and the amount can be calculated from the structure.

[0107] 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).

[0108] (Solvent) The solvent is preferably a solvent capable of dissolving or dispersing the components blended in the composition. As the solvent, an organic solvent can be preferably used. Specific examples of the solvent include alcohols, ethers, ketones, amides, esters, hydrocarbons, etc.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] (Other Optional Components) The present composition may further contain, as other components, components other than the onium salt (B), acid diffusion controller, polymer (F), and solvent (hereinafter also referred to as "other optional components"). Examples of other optional components include aromatic carboxylic acids (e.g., benzoic acid, salicylic acid, benzenedicarboxylic acid, etc.), aliphatic carboxylic acids (e.g., acetic acid, oxalic acid, pyruvic acid, 1-adamantanecarboxylic acid, etc.), surfactants, alicyclic skeleton-containing compounds (e.g., 2-adamantanone, t-butyl deoxycholate, etc.), sensitizers, and uneven distribution promoters.

[0114] <Method for producing radiation-sensitive composition> The present composition can be produced, for example, by mixing the polymer (P) and compound (A), as well as components such as a solvent as necessary, in a desired ratio, and filtering the resulting mixture, preferably using a filter (for example, a filter with a pore size of about 0.2 μm). The solids concentration of the present 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 present 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 present composition within the above range, good coatability can be achieved, and a good resist pattern shape can be obtained.

[0115] 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.

[0116] <<Method of Forming Resist Pattern>> The method of 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 of forming a resist pattern according to the present disclosure include a line-and-space pattern and a hole pattern. Because the method of forming a resist pattern according to the present disclosure uses the present composition to form a resist film, it is possible to form a resist pattern with good sensitivity, reduced CDU, and good resolution. Each step will be described below.

[0117] <Coating Step> In the coating step, the composition is applied to one side of a substrate to form a resist film on the substrate. Conventional substrates can be used as the substrate on which the resist film is formed, 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 used to form a resist film on the substrate. Examples of methods for applying the composition include spin coating, casting coating, and roll coating. After coating, a soft bake (also referred to as SB or pre-bake (PB)) 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, and more preferably 20 to 500 nm.

[0118] <Exposure Step> 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; 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 present 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.

[0119] 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 acid generated from a compound that generates acid upon exposure (such as a radiation-sensitive acid generator, an acid diffusion controller, or a polymer (P) containing a third structural unit). 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.

[0120] <Developing Step> In the developing step, the exposed resist film is developed. This allows a desired resist pattern to be formed. After development, the resist film is generally washed with a rinse liquid such as water or alcohol, and then dried. The developing method in the developing step may be alkali development or organic solvent development.

[0121] In the case of alkaline development, examples of the developer used for development include an alkaline aqueous solution containing at least one alkaline compound dissolved therein, such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38% by mass TMAH solution is 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, and solvents containing the above organic solvents.

[0122] Examples of the developing method include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of developing by piling up the developer on the surface of the substrate by surface tension and leaving it to stand for a certain period of time (puddle method), a method of spraying the developer onto the surface of the substrate (spray method), and a method of continuously discharging the developer while scanning a developer discharging nozzle at a constant speed onto a substrate that is rotating at a constant speed (dynamic dispense method).

[0123] <Compound> According to the present disclosure, there is provided a compound represented by the following formula (1B): (In formula (1B), X １ teeth* １ -SO ２ -NH- or * １ -NH-SO ２ - is. １ is R １ Represents a bond with R. １ and A ２ is R １ is a monovalent organic group, and A ２ is a divalent organic group having an aromatic ring, or R １ and A ２ are aligned together -SO ２represents a group having a ring containing —NH— in the ring skeleton and an aromatic ring. ＋ is a substituted or unsubstituted iodonium cation, or a sulfonium cation having at least one group selected from the group consisting of a fluoro group, a bromo group, an iodo group, a haloalkyl group, a cyano group, a carbonyl group, and a sulfonyl group.

[0124] The compound represented by the formula (1B) can provide a radiation-sensitive composition excellent in sensitivity, CDU performance, and storage stability. １ is a divalent organic group having an aromatic ring, or R １ and A １ are aligned together -SO ２ It is the same as compound (A) except that it represents a group having a ring containing —NH— in the ring skeleton and an aromatic ring.

[0125] The compound represented by the above formula (1B) can be synthesized by appropriately combining standard methods in organic chemistry. For example, ２ -SO ３ － " and a group R １ The compound represented by the formula (1B) can be obtained by reacting a sulfonamide having a partial structure corresponding to the group A in a suitable solvent in the presence of a catalyst, if necessary. ２ and a partial structure corresponding to a part of SO ３ － and a compound having a group A ２ The partial structure corresponding to the remainder of the group "-X １ -R １ " and a compound having the formula (1B) in a suitable solvent in the presence of a catalyst, as necessary, to obtain the compound represented by formula (1B). However, the method for synthesizing the compound represented by formula (1B) is not limited to the above.

[0126] 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.

[0127] The weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer were measured as follows. [Weight average molecular weight (Mw) and number average molecular weight (Mn)] Using Tosoh GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL), the measurements were carried out by gel permeation chromatography (GPC) using monodisperse polystyrene as the standard under the following analytical conditions: flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1.0 mass%, sample injection volume: 100 μL, column temperature: 40°C, detector: differential refractometer. The dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0128] 1. Synthesis of Compound (Radiation-Sensitive Acid Generator [A]) [Synthesis Example 1] Synthesis of Compound (A-1) A compound represented by the following formula (A-1) was synthesized according to the following synthesis scheme.

[0129] To a container containing dichloromethane (100 mL), carboxylic acid-containing radiation-sensitive acid generator (Z-1) (20 mmol), methanesulfonamide (30 mmol), 1,1'-carbonylbis-1H-imidazole (30 mmol), and 1,8-diazabicyclo[5.4.0]-7-undecene (30 mmol) were added under ice cooling. The mixture was then returned to room temperature and stirred. The organic layer was washed twice with dilute hydrochloric acid. The organic layer was dried over sodium sulfate and filtered. The solvent was distilled off, and the crude product was purified using a column to obtain radiation-sensitive acid generator (A-1).

[0130] [Synthesis Examples 2 to 4, 12, 13, 15, 16, 18, 19] Compounds represented by the following formulas (A-2) to (A-4), (A-12), (A-13), (A-15), (A-16), (A-18), and (A-19) were synthesized in the same manner as in Synthesis Example 1, except that the synthetic raw materials and precursors of compounds (A-2) to (A-4), (A-12), (A-13), (A-15), (A-16), (A-18), and (A-19) were appropriately changed.

[0131] Synthesis Example 5 Synthesis of Compound (A-5) A compound represented by the following formula (A-5) was synthesized according to the following synthesis procedure.

[0132] 20.0 mmol of p-aminoacetophenone, 20.0 mmol of trifluoromethanesulfonyl chloride, 20.0 mmol of pyridine, and 40 g of dichloromethane were added to a reaction vessel and stirred at room temperature for 3 hours. Subsequently, a saturated aqueous solution of ammonium chloride was added to the reaction solution to terminate the reaction, and then ethyl acetate was added for extraction and the organic layer was separated. The resulting organic layer was dried over sodium sulfate, and the solvent was distilled off. Purification by recrystallization afforded sulfonamide (Z-2) in good yield.

[0133] Compound (Z-2) (15 mmol), compound (Z-3) (10 mmol), and p-toluenesulfonic acid monohydrate (2 mmol) were added to a vessel containing toluene (100 mL). The mixture was heated under reflux for 3 hours while removing water using a Dean-Stark apparatus. The mixture was returned to room temperature, and ethyl acetate was added. The organic layer was washed twice with an aqueous solution of sodium hydrogen carbonate. The organic layer was dried over sodium sulfate and filtered. The solvent was distilled off, and the crude product was purified using a column to obtain compound (A-5).

[0134] [Synthesis Examples 6 to 8, 14, 17] Compounds represented by the following formulas (A-6) to (A-8), (A-14), and (A-17) were synthesized in the same manner as in Synthesis Example 5, except that the synthetic raw materials and precursors for compounds (A-6) to (A-8), (A-14), and (A-17) were appropriately changed.

[0135] Synthesis Example 9 Synthesis of Compound (A-9) A compound represented by the following formula (A-9) was synthesized according to the following synthesis procedure.

[0136] 20.0 mmol of 4-acetylbenzenesulfonyl chloride and 40.0 mmol of 4-iodoaniline per 40 g of ethanol were added to a reaction vessel and stirred. Thereafter, the reaction solution was cooled to 0°C, and 2N hydrochloric acid was added to terminate the reaction. After that, ethyl acetate was added for extraction and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was distilled off, and the crude product was purified by column chromatography to obtain the sulfonamide (Z-4) in good yield.

[0137] Subsequently, a compound represented by the following formula (A-9) was synthesized in the same manner as in Synthesis Example 5, except that compound (Z-4) was used instead of compound (Z-2).

[0138] Synthesis Example 10 A compound represented by the following formula (A-10) was synthesized in the same manner as in Synthesis Example 9, except that the synthetic raw materials and precursors for compound (A-10) were appropriately changed.

[0139] Synthesis Example 11 Synthesis of Compound (A-11) Compound (A-11) was synthesized according to the following synthesis procedure.

[0140] To a solution of 60 mmol of 4-(trifluoromethoxy)aniline in 60 mL of dry dichloromethane placed in an ice bath under argon, a solution of 20 mmol of chlorosulfonic acid in 12 mL of dichloromethane was added. The reaction mixture was stirred at 0°C for 30 minutes and at room temperature for 1 hour. The precipitate was collected by filtration and dried under high vacuum. This material was suspended in 18 mL of toluene, and 20 mmol of phosphorus pentachloride was added. The mixture was stirred at 75°C for 3 hours, cooled to room temperature, and filtered. The solid residue was washed with toluene, and the filtrate was collected. The filtrate was evaporated to dryness under high vacuum. The crude product (Z-5) was used in the next step without further purification.

[0141] The compound (Z-5) obtained in the above step, 20.0 mmol of 4'-hydroxyacetophenone, 20.0 mmol of pyridine, and 40 g of dichloromethane were added and stirred at room temperature for 3 hours. Subsequently, a saturated aqueous solution of ammonium chloride was added to the reaction solution to terminate the reaction, and then ethyl acetate was added for extraction and the organic layer was separated. The resulting organic layer was dried over sodium sulfate, the solvent was distilled off, and the residue was purified by column chromatography to obtain the sulfonamide (Z-6) in good yield.

[0142] Subsequently, a compound represented by the following formula (A-11) was synthesized in the same manner as in Synthesis Example 5, except that compound (Z-6) was used instead of compound (Z-2).

[0143] The structural formulae of the compounds (A-1) to (A-19) (radiation-sensitive acid generators (A-1) to (A-19)) are shown below.

[0144] 2. Polymer Synthesis The monomers used in the synthesis of the polymer ([P] polymer) are shown below.

[0145]

[0146] [Synthesis Example P-1] Synthesis of Polymer (P-1) Compound (M-1) and compound (M-4) were dissolved in 1-methoxy-2-propanol (200 parts by mass relative to the total monomer amount) so that the molar ratio was 40 / 60. Next, azobisisobutyronitrile was added as an initiator in an amount of 6 mol% relative to the total monomer amount to prepare a monomer solution. Meanwhile, 1-methoxy-2-propanol (100 parts by mass relative to the total monomer amount) was added to an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 85°C for an additional 3 hours. After completion of the polymerization reaction, the polymerization solution was cooled to room temperature.

[0147] The cooled polymerization solution was poured into hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane (100 parts by mass relative to the polymerization solution) and then dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and a hydrolysis reaction was carried out at 70°C for 6 hours with stirring.

[0148] After the reaction was completed, the remaining solvent was distilled off, and the resulting solid was dissolved in acetone (100 parts by mass). This solution was added dropwise to 500 parts by mass of water to coagulate the polymer, and the resulting solid was filtered off. The resulting mixture was dried at 50°C for 12 hours to obtain a white powdery polymer (P-1).

[0149] Synthesis Examples P-2 to P-11 Polymers (P-2) to (P-11) were synthesized in the same manner as in Synthesis Example P-1, except that the monomer types and ratios were changed as shown in Table 1.

[0150] [Synthesis Example P-12] Synthesis of Polymer (P-12) 4-Hydroxystyrene, compound (M-4), and compound (M-3) were dissolved in 1-methoxy-2-propanol (200 parts by mass relative to the total amount of monomers) so that the molar ratio was 30 / 60 / 10. Next, azobisisobutyronitrile was added as an initiator in an amount of 6 mol% relative to the total amount of monomers to prepare a monomer solution. Meanwhile, 1-methoxy-2-propanol (100 parts by mass relative to the total amount of monomers) was added to an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 85°C for an additional 3 hours. After completion of the polymerization reaction, the polymerization solution was cooled to room temperature.

[0151] The cooled polymerization solution was poured into hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with 100 parts by mass of hexane relative to the polymerization solution, and then dried at 50°C for 12 hours to obtain a white powdery polymer (P-12).

[0152] [Synthesis Examples P-13 to P-15] Polymers (P-13) to (P-15) were synthesized in the same manner as in Synthesis Example P-12, except that the monomer types and ratios were changed as shown in Table 1. In Table 1, "4HS" stands for 4-hydroxystyrene.

[0153]

[0154] 3. Preparation of Radiation-Sensitive Compositions Among the components used in preparing the radiation-sensitive compositions of Examples 1 to 54 and Comparative Examples 1 and 2, those other than those mentioned above are listed below.

[0155] <[B] Radiation-sensitive Acid Generator> Compounds represented by the following formulae (B-1) to (B-9):

[0156] <[C] Acid Diffusion Controller> Compounds represented by the following (C-1) to (C-8):

[0157] <[D] Organic Solvent> D-1: Propylene glycol monomethyl ether acetate D-2: Methyl 2-hydroxyisobutyrate D-3: Propylene glycol 1-monomethyl ether D-4: Diacetone alcohol

[0158] Example 1 100 parts by mass of a polymer (P-1), 10 parts by mass of a radiation-sensitive acid generator (A-1), 10 parts by mass of a radiation-sensitive acid generator (B-1), 20 mol % of an acid diffusion controller (C-1) based on the total amount of the radiation-sensitive acid generator (A-1) and the radiation-sensitive acid generator (B-1), 2,000 parts by mass of an organic solvent (D-1), and 4,800 parts by mass of an organic solvent (D-2) were blended and mixed, and the mixture was then filtered through a filter having a pore size of 0.20 μm to prepare a radiation-sensitive composition (R-1).

[0159] Examples 2 to 54 and Comparative Examples 1 and 2 Radiation-sensitive compositions (R-2) to (R-54) and (CR-1) and (CR-2) were prepared in the same manner as in Example 1, except that the types and amounts of each component were changed as shown in Tables 2 and 3. In Tables 2 and 3, the amount of [C] acid diffusion controller represents the molar ratio (mol %) to the total amount of [A] radiation-sensitive acid generator, [B] radiation-sensitive acid generator, and [P] monomer providing the third structural unit used in the synthesis of the polymer.

[0160]

[0161]

[0162] 4. Formation of Resist Pattern (1) Formation of Resist Pattern by EUV Exposure Using each of the radiation-sensitive compositions (R-1) to (R-54), (CR-1), and (CR-2), a resist pattern was formed by EUV exposure. Details of the pattern formation method by EUV exposure are as follows. Each radiation-sensitive composition was applied to the surface of a 12-inch silicon wafer on which a 20-nm-thick underlayer film (AL412 (manufactured by Brewer Science)) had been formed, using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron Ltd.). After soft baking (SB) at 100°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a 40-nm-thick resist film. Next, this resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3300", manufactured by ASML, NA=0.33, illumination conditions: Conventional s=0.89). The resist film was subjected to PEB (post-exposure bake) at 100°C for 60 seconds. Next, it was developed using a 2.38 wt% aqueous TMAH solution at 23°C for 30 seconds to form a positive-tone 50 nm pitch / 25 nm contact hole pattern. (2) Formation of Resist Pattern by KrF Exposure Resist patterns were formed by KrF exposure using each of the radiation-sensitive compositions (R-1) to (R-54), (CR-1), and (CR-2). Details of the pattern formation method by KrF exposure are as follows. Each radiation-sensitive composition was applied to the surface of a 12-inch silicon wafer on which a 20-nm-thick underlayer film (DUV42 (Nissan Chemical Industries, Ltd.)) had been formed using a spin coater (CLEAN TRACK ACT12, Tokyo Electron Limited). After spin-back at 130°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a 70-nm-thick resist film. Next, the resist film was irradiated with KrF light using a KrF exposure machine (model "S210D," Nikon Corporation, NA = 0.55, illumination conditions: Annular s = 0.8, mask 150 nm LS). After exposure, the resist film was subjected to PEB at 110°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 150-nm line-and-space pattern.

[0163] 5. Evaluation The sensitivity, CDU performance, and storage stability of each radiation-sensitive composition were evaluated by measuring each of the resist patterns formed above according to the methods described below. 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 below.

[0164] [Sensitivity] In the formation of a resist pattern by EUV exposure in the above 4. (1), 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. The sensitivity was 56 mJ / cm ２ "S" (very good) for less than 56 mJ / cm ２ More than 58mJ / cm ２ "A" (good) if less than 58 mJ / cm ２ More than 61mJ / cm ２ "B" (fairly good) in the following cases: 61 mJ / cm ２ When the test result exceeded this, it was judged as "C" (poor).

[0165] [CDU Performance] In the formation of a resist pattern by EUV exposure in 4. (1) above, the 25 nm contact hole pattern was observed from above using the scanning electron microscope, and a total of 800 lengths were measured at random points. The dimensional variation (3σ) was determined and used as the CDU performance (nm). The smaller the CDU value, the smaller the variation in hole diameter over a long period, and the better the result. The CDU performance was evaluated as "S" (very good) when the CDU was less than 3.4 nm, "A" (good) when it was 3.4 nm or more but less than 3.6 nm, "B" (fairly good) when it was 3.6 nm or more but less than 3.8 nm, and "C" (poor) when it was 3.8 nm or more.

[0166] [Storage Stability] After preparing the radiation-sensitive composition, it was stored at -15°C for 2 weeks or at 35°C for 2 weeks. Thereafter, in the resist pattern formation by KrF exposure described in 4. (2) above, the optimal exposure dose for forming a 150 nm line and space pattern was determined. The smaller the difference between the optimal exposure dose of the radiation-sensitive composition stored at -15°C for 2 weeks and the optimal exposure dose of the radiation-sensitive composition stored at 35°C for 2 weeks, the better the storage stability of the radiation-sensitive composition. Based on the optimal exposure dose of the radiation-sensitive composition stored at -15°C for two weeks, the radiation-sensitive composition stored at 35°C for two weeks was rated as "C" if it increased sensitivity by 1.0% or more or decreased sensitivity by 1.0% or more, "B" if it increased sensitivity by less than 1.0% but 0.7% or more or decreased sensitivity by less than 1.0% but 0.7% or more, and "A" if it increased sensitivity by less than 0.7% but 0.2% or more or decreased sensitivity by less than 0.7% but 0.2% or more. Otherwise, it was rated as "S".

[0167]

[0168]

[0169] As is clear from the results in Tables 4 and 5, the radiation-sensitive compositions of Examples 1 to 54 all had good sensitivity and CDU performance while ensuring storage stability, compared to the radiation-sensitive compositions of Comparative Examples 1 and 2.

[0170] The above results demonstrate that the radiation-sensitive resin composition and method for forming a resist pattern according to the present disclosure can improve sensitivity and CDU while ensuring storage stability. Therefore, the radiation-sensitive composition and method for forming a resist pattern according to the present disclosure can be suitably used for forming fine resist patterns in lithography processes for various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. A radiation-sensitive composition comprising: a polymer having an acid-dissociable group; and a compound represented by the following formula (1): (In formula (1), X １ teeth* １ -SO ２ -NH- or * １ -NH-SO ２ - is. １ is R １ Represents a bond with R. １ and A １ is R １ is a monovalent organic group, and A １ is a divalent organic group, or R １ and A １ are aligned together -SO ２ represents a group having a ring structure containing —NH— in the ring skeleton. ＋ is a substituted or unsubstituted iodonium cation, or a sulfonium cation having at least one group selected from the group consisting of a fluoro group, a bromo group, an iodo group, a haloalkyl group, a cyano group, a carbonyl group, and a sulfonyl group, provided that M ＋ is an unsubstituted iodonium cation, A １ has an aromatic ring.) 2. A in the above formula (1) １ The radiation-sensitive composition according to claim 1 , wherein has an aromatic ring.

3. X in the above formula (1) １ But, A １ or is bonded directly to an aromatic ring in ２ A via -, -CO-O-, -O-CO-, -CO-NH- or -NH-CO- １ The radiation-sensitive composition according to claim 2 , wherein the aromatic ring is bonded to the aromatic ring in the aromatic ring.

4. The radiation-sensitive composition according to claim 1, wherein the compound represented by formula (1) is represented by formula (1A): (In formula (1A), R ２ and W １ is R ２ is a monovalent organic group, and W １ is a divalent group obtained by removing two hydrogen atoms from the ring portion of a substituted or unsubstituted aromatic ring, or R ２ and W １ are aligned together -SO ２ It represents a condensed ring structure of a heterocycle containing —NH— in the ring skeleton and an aromatic ring. ２ represents a single bond, —O—, —CO—, —S—, —NH—, or —SO ２ -, -CO-O-, -O-CO-, -CO-NH- or -NH-CO-. １ is -O-, -CO-, -S-, -NH-, -SO ２ -, -CO-O-, -O-CO-, -CO-NH-, -NH-CO-, a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted hydrocarbon group in which some of the methylene groups are -O-, -CO-, -S-, -NH-, or -SO ２ is a divalent group substituted with -, -CO-O-, -O-CO-, -NH-CO- or -CO-NH-. ｆ１ and R ｆ２ are each independently a hydrogen atom, a fluorine atom, an alkyl group, or a fluoroalkyl group. m1 is an integer of 1 to 4. X １ and M ＋ has the same meaning as the above formula (1).

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

6. -SO ２ 2. The radiation-sensitive composition according to claim 1, further comprising an onium salt (B) comprising a sulfonate anion having no —NH— group and a radiation-sensitive cation.

7. The radiation-sensitive composition according to claim 6, wherein the radiation-sensitive cation in the onium salt (B) is a substituted or unsubstituted iodonium cation, or a sulfonium cation having at least one group selected from the group consisting of a fluoro group, a bromo group, an iodo group, a haloalkyl group, a cyano group, a carbonyl group, and a sulfonyl group.

8. The radiation-sensitive composition according to claim 6, wherein the sulfonate anion in the onium salt (B) has an iodine group.

9. The radiation-sensitive composition according to claim 6, wherein the content of the compound represented by formula (1) is 10 to 80 parts by mass per 100 parts by mass of the total amount of the compound represented by formula (1) and the onium salt (B).

10. The polymer is -SO ２ 2. The radiation-sensitive composition according to claim 1, comprising a structural unit derived from an onium salt comprising a sulfonate anion having no —NH— and a radiation-sensitive cation.

11. The radiation-sensitive composition according to claim 1, further comprising an acid diffusion controller.

12. A method for forming a resist pattern, comprising: forming a resist film on a substrate using the radiation-sensitive composition according to any one of claims 1 to 11; exposing the resist film; and developing the exposed resist film.

13. The method for forming a resist pattern according to claim 12, wherein the resist film is exposed using extreme ultraviolet light.

14. A radiation-sensitive acid generator represented by the following formula (1B): (In formula (1B), X １ teeth* １ -SO ２ -NH- or * １ -NH-SO ２ - is. １ is R １ Represents a bond with R. １ and A ２ is R １ is a monovalent organic group, and A ２ is a divalent organic group having an aromatic ring, or R １ and A ２ are aligned together -SO ２ represents a group having a ring containing —NH— in the ring skeleton and an aromatic ring. ＋ is a substituted or unsubstituted iodonium cation, or a sulfonium cation having at least one group selected from the group consisting of a fluoro group, a bromo group, an iodo group, a haloalkyl group, a cyano group, a carbonyl group, and a sulfonyl group.

15. A compound represented by the following formula (1B): (In formula (1B), X １ teeth* １ -SO ２ -NH- or * １ -NH-SO ２ - is. １ is R １ Represents a bond with R. １ and A ２ is R １ is a monovalent organic group, and A ２ is a divalent organic group having an aromatic ring, or R １ and A ２ are aligned together -SO ２ represents a group having a ring containing —NH— in the ring skeleton and an aromatic ring. ＋ is a substituted or unsubstituted iodonium cation, or a sulfonium cation having at least one group selected from the group consisting of a fluoro group, a bromo group, an iodo group, a haloalkyl group, a cyano group, a carbonyl group, and a sulfonyl group.

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