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

Abstract

This radiation-sensitive composition comprises a polymer (A) containing a structural unit represented by formula (1) and satisfies at least one among requirement 1 and requirement 2, wherein at least one selected from the group consisting of the polymer (A) contained in said composition and a radiation-sensitive onium salt (B) of a non-polymer has an iodine atom. Requirement 1: The polymer (A) further contains a structural unit derived from a radiation-sensitive onium salt. Requirement 2: The radiation-sensitive onium salt (B) of the non-polymer is further contained. In formula (1), L1 is a single bond or a divalent organic group. P1 is an acid-dissociable group.

Description

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

[0001] [Cross-Reference to Related Applications] This application claims priority to Japanese Patent Application No. 2024-152723, 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, a polymer, and a 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 those from 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 the generated 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] As the structures of various electronic devices become finer, there is a demand for even finer resist patterns in lithography processes. Furthermore, in response to the demand for even finer resist patterns, various efforts have been made to improve the resolution and resist pattern shape of radiation-sensitive compositions used in lithographic microfabrication (see, for example, Patent Document 1). Patent Document 1 discloses that a resist pattern can be formed with good CDU (critical dimension uniformity) by incorporating into a resist composition a salt composed of a sulfonate anion having a partial structure in which a halogen atom or a haloalkyl group is bonded to a benzene ring, and a cation.

[0004] JP 2023-36004 A

[0005] In recent years, efforts to further reduce the size of resist patterns have been progressing rapidly, and attempts have been made to form patterns with line widths of 40 nm or less. Radiation-sensitive compositions used to form resist patterns are required to exhibit good CDU performance even when forming such fine resist patterns.

[0006] As resist patterns become finer, the variation in pattern dimensions tends to increase. This raises concerns that defects such as pattern connection may easily occur. From the viewpoint of obtaining a radiation-sensitive composition that exhibits excellent lithography performance, it is important that the change in CDU performance due to differences in exposure conditions is small and that the exposure margin (hereinafter also referred to as "CDU exposure margin") is wide.

[0007] Furthermore, if the components (especially resin components) of the radiation-sensitive composition used to form the resist pattern have insufficient solubility in the portions (exposed or unexposed portions) that are to be dissolved in a developer after exposure, a pattern of the desired shape cannot be obtained, or residue that did not dissolve in the developer adheres to the pattern surface, resulting in the occurrence of defects. As resist patterns become finer, the occurrence of such defects has a greater impact on the performance of semiconductor devices. Therefore, it is necessary to suppress the occurrence of defects as much as possible while achieving further finer resist patterns.

[0008] The present disclosure has been made in consideration of the above-mentioned problems, and a primary object of the present disclosure is to provide a radiation-sensitive composition and a method for forming a resist pattern that exhibit good CDU performance, show little change in CDU performance due to differences in exposure conditions, and are capable of forming a resist pattern with few defects. Another object of the present disclosure is to provide a polymer and a compound for obtaining a radiation-sensitive composition that exhibits good CDU performance, show little change in CDU performance due to differences in exposure conditions, and are capable of forming a resist pattern with few defects.

[0009] The present inventors have found that the above-mentioned problems can be solved by using a radiation-sensitive composition having a specific composition. Specifically, the present disclosure provides the following radiation-sensitive composition, method for forming a resist pattern, polymer, and compound.

[0010] In one aspect, the present disclosure provides a radiation-sensitive composition comprising a polymer (A) containing a structural unit represented by the following formula (1), and satisfying one or more of the following requirements 1 and 2: requirement 1: the polymer (A) further contains a structural unit derived from a radiation-sensitive onium salt, and requirement 2: the composition further contains a non-polymeric radiation-sensitive onium salt (B), and at least one selected from the group consisting of the polymer (A) and the radiation-sensitive onium salt (B) contains an iodine atom. (In formula (1), R １ and R ２ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a fluoromethyl group. １ is a single bond or a divalent organic group. １ is an acid-dissociable group.)

[0011] In another aspect, the present disclosure provides 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, exposing the resist film to light, and developing the exposed resist film.

[0012] In another aspect, the present disclosure provides a polymer that includes a structural unit represented by the above formula (1) and has an iodine atom.

[0013] In yet another aspect, the present disclosure provides a compound represented by the following formula (2): (In formula (2), R １ and R ２ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a fluoromethyl group. １ is a single bond or a divalent organic group. １Ａ is an acid-dissociable group having an iodine atom.

[0014] According to the present disclosure, it is possible to obtain a radiation-sensitive composition that exhibits good CDU performance, exhibits little change in CDU performance due to differences in exposure conditions, and is capable of forming a resist pattern with few defects.

[0015] Matters relating to the implementation of the present disclosure 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 limit and upper limit.

[0016] 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 obtained by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound). The term "aromatic ring" refers to an aromatic hydrocarbon ring and an aromatic heterocycle.

[0017] The "main chain" of a polymer refers to the "backbone" portion of the polymer, which is the longest chain of atoms. It is acceptable for this "backbone" 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 "backbone" of the polymer. A "structural unit" refers to a unit that primarily constitutes the main chain structure, and at least two or more units are included in the main chain structure. A structural unit is typically a monomer unit. The term "structural unit" also includes a unit obtained by reacting a monomer unit having a reactive group with a compound having a functional group capable of reacting with the reactive group, and a unit obtained by polymerizing a monomer protected with a protecting group such as an alkali-dissociable group and then deprotecting the monomer by hydrolysis. "(Meth)acrylate" is a term that encompasses both "acrylate" and "methacrylate."

[0018] 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 categorized as "substituted monovalent hydrocarbon groups," and fluoroalkanediyl groups are categorized as "substituted divalent hydrocarbon groups." The same applies to other groups to which "substituted or unsubstituted" is attached.

[0019] <Radiation-Sensitive Composition> The radiation-sensitive composition of the present disclosure (hereinafter also referred to as "the composition") contains a polymer (A) that is derived from a maleimide compound and includes a structural unit having a protected carboxy. The composition also includes a non-polymeric radiation-sensitive onium salt, a polymer that includes a structural unit derived from the radiation-sensitive onium salt, or both. Hereinafter, the radiation-sensitive onium salt and the polymer that includes a structural unit derived from the radiation-sensitive onium salt are also referred to as the "onium salt component."

[0020] Specifically, with regard to the onium salt component, the present composition satisfies one or more of Requirement 1 and Requirement 2 shown below. Requirement 1: The polymer (A) further contains a structural unit derived from a radiation-sensitive onium salt. Requirement 2: The composition further contains a non-polymeric radiation-sensitive onium salt (B). Note that, hereinafter, of the structural units contained in the polymer (A), a structural unit derived from a maleimide compound and having a protected carboxyl will also be referred to as a "first structural unit," and a structural unit derived from a radiation-sensitive onium salt will also be referred to as a "second structural unit."

[0021] Polymer (A) The polymer (A) may be a polymer containing a first structural unit but not a second structural unit, or may be a polymer containing a first structural unit and a second structural unit. The polymer (A) may further contain a structural unit different from the first structural unit and the second structural unit (hereinafter also referred to as "other structural unit"). The polymer (A) preferably constitutes the base resin of the present composition. Here, the base resin is typically a component that contains a structural unit having an acid-dissociable group in a predetermined proportion or more (e.g., 20 mol % or more), thereby contributing to the solubility of the present composition in a developer. The base resin may be composed of two or more polymers.

[0022] Radiation-sensitive onium salt (B) The radiation-sensitive onium salt (B) is a component that is optionally blended into the composition. The radiation-sensitive onium salt (B) is a substance that generates an acid upon irradiation with radiation, and typically has a radiation-sensitive onium cation and an organic anion that is the conjugate base of the acid. The organic anion is usually an anion obtained by removing a proton from the acid group of an organic acid. Herein, the term "radiation" encompasses electron beams (visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), etc.) and electromagnetic waves (X-rays, gamma rays, etc.).

[0023] The radiation-sensitive onium salt (B) may be a so-called radiation-sensitive acid generator or an acid diffusion controller. The present composition may contain both a radiation-sensitive acid generator and an acid diffusion controller as the radiation-sensitive onium salt (B). The radiation-sensitive acid generator is a substance that, upon exposure, generates in the present composition a strong acid capable of cleaving an acid-dissociable group possessed by a component in the radiation-sensitive composition from the component. Hereinafter, the radiation-sensitive acid generator will also be simply referred to as "acid generator." The acid diffusion controller is a substance that can suppress the diffusion of an acid derived from the acid generator generated upon exposure in the resist film, thereby suppressing a chemical reaction caused by the acid in unexposed regions. The acid diffusion controller typically generates in the present composition a weak acid that, upon exposure, does not induce cleavage of an acid-dissociable group possessed by a component in the radiation-sensitive composition.

[0024] The radiation-sensitive onium salt (B) is classified as an acid generator or an acid diffusion controller depending on the strength of its acid relative to the components in the composition (specifically, the monomer that provides the second structural unit in the polymer (A) and, in the case where two or more types of radiation-sensitive onium salt (B) are contained, the other radiation-sensitive onium salts). The level of acidity can be evaluated by the acid dissociation constant (pKa). For example, the acid dissociation constant of the acid generated by the acid diffusion controller is usually −3 or more, preferably −1≦pKa≦7, and more preferably 0≦pKa≦5. The molecular weight of the radiation-sensitive onium salt (B) is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0025] In terms of ease of adjusting the sensitivity and lithography properties of the composition and providing a high degree of freedom of selection, the composition preferably contains a radiation-sensitive onium salt (B) as the onium salt component. That is, the composition preferably satisfies Requirement 2. Furthermore, in terms of improving CDU performance and minimizing changes in CDU performance due to differences in exposure conditions (i.e., widening the CDU exposure margin), the composition preferably contains, as the radiation-sensitive onium salt (B), a first onium salt that generates an acid upon exposure and a second onium salt that generates an acid with a weaker acidity than the acid generated by the first onium salt upon exposure. Note that when the composition contains a first onium salt and a second onium salt, typically, the first onium salt is an acid generator, and the second onium salt is an acid diffusion controller.

[0026] Iodine-Containing Component The composition further contains a component having an iodine atom (iodine-containing component). Specifically, in the composition, at least one selected from the group consisting of the polymer (A) and the radiation-sensitive onium salt (B) contained in the composition contains an iodine atom. The composition, which contains the polymer (A), an onium salt component, and an iodine-containing component, has high sensitivity and exhibits excellent CDU performance, and has a wide and favorable CDU exposure margin. In addition, the resist pattern obtained from the composition generates few defects, resulting in excellent defect suppression properties.

[0027] The iodine-containing component may be a polymer (A) or a radiation-sensitive onium salt (B). Alternatively, both the polymer (A) and the radiation-sensitive onium salt (B) may be iodine-containing components. When the polymer (A) is an iodine-containing component, any of the structural units constituting the polymer (A) may have an iodine atom. That is, when the polymer (A) is an iodine-containing component, the first structural unit in the polymer (A) may have an iodine atom, or other structural units may have an iodine atom. When the polymer (A) contains a second structural unit, the second structural unit may have an iodine atom. Furthermore, two or more of the first structural unit, the second structural unit, and other structural units in the polymer (A) may have an iodine atom. Hereinafter, a polymer containing a first structural unit and an iodine atom will also be referred to as "polymer (A1)."

[0028] It is preferable that the first structural unit in the polymer (A) contains an iodine atom, since a radiation-sensitive composition having better CDU performance can be obtained. Also, it is preferable that the polymer (A) contains a second structural unit, and the second structural unit in the polymer (A) contains an iodine atom, since the sensitivity of the radiation-sensitive composition can be increased.

[0029] Similarly, when the radiation-sensitive onium salt (B) is an iodine-containing component, the manner in which an iodine atom is introduced into the radiation-sensitive onium salt (B) is not particularly limited. That is, when the radiation-sensitive onium salt (B) constitutes an iodine-containing component, the acid generator may contain an iodine atom, the acid diffusion controller may contain an iodine atom, or both may contain an iodine atom. Furthermore, of the radiation-sensitive onium cation and organic anion constituting the radiation-sensitive onium salt (B), the radiation-sensitive onium cation may contain an iodine atom, the organic anion may contain an iodine atom, or both may contain an iodine atom.

[0030] When the radiation-sensitive onium salt (B) contains an organic anion having an iodine atom, this is preferred because it can improve the sensitivity and CDU performance of the composition in a well-balanced manner. Furthermore, when it contains a radiation-sensitive onium cation having an iodine atom, this is preferred because it can further enhance the CDU performance of the composition. Furthermore, a radiation-sensitive onium salt composed of a radiation-sensitive onium cation having an iodine atom and an organic anion is useful because it allows for greater freedom in selecting the organic anion and makes it easy to adjust the sensitivity, etc., of the composition. When the radiation-sensitive onium cation contains an iodine atom, the radiation-sensitive onium cation may be an iodonium cation or a cation having an iodo group (preferably a sulfonium cation or an iodonium cation).

[0031] When the radiation-sensitive onium salt (B) contains iodine atoms, the number of iodine atoms per molecule of the onium salt is not particularly limited. The number of iodine atoms per molecule of the iodine-containing radiation-sensitive onium salt (B) may be 1 or more, and preferably 2 or more. From the viewpoints of ease of synthesis and solubility in a developer, the number of iodine atoms per molecule of the radiation-sensitive onium salt (B) is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less.

[0032] At least a portion of the radiation-sensitive onium salt (B) blended in the present composition preferably contains an iodine atom, such as an embodiment in which one selected from the group consisting of the first onium salt and the second onium salt contains an iodine atom, or an embodiment in which both the first onium salt and the second onium salt contain an iodine atom.

[0033] Specific embodiments of the radiation-sensitive composition that contains a polymer (A), satisfies one or more of Requirement 1 and Requirement 2, and in which at least one selected from the group consisting of the polymer (A) and the radiation-sensitive onium salt (B) contained in the composition has an iodine atom include, for example, the following embodiments [1] to [5] and combinations of two or more of these embodiments. Embodiment [1]: Contains a polymer (A) and a radiation-sensitive onium salt (B), in which the radiation-sensitive onium salt (B) includes a first onium salt (acid generator) and a second onium salt (acid diffusion controller), and the first onium salt and the second onium salt have an iodine atom. Embodiment [2]: Contains a polymer (A) and a radiation-sensitive onium salt (B), in which the radiation-sensitive onium salt (B) includes a first onium salt and a second onium salt, and the first onium salt has an iodine atom. Aspect [3]: The composition contains a polymer (A) and a radiation-sensitive onium salt (B), wherein the radiation-sensitive onium salt (B) includes a first onium salt and a second onium salt, and the second onium salt of the first and second onium salts has an iodine atom. Aspect [4]: ​​The composition contains a polymer (A) and a radiation-sensitive onium salt (B), wherein the radiation-sensitive onium salt (B) includes a first onium salt and a second onium salt, and the polymer (A) has an iodine atom. Aspect [5]: The composition contains a polymer (A), wherein the polymer (A) includes a first structural unit and a second structural unit, and the polymer (A) has an iodine atom.

[0034] The radiation-sensitive compositions of the above embodiments [1] to [5] may further contain other solid components (such as an acid generator, an acid diffusion controller, or a high-fluorine-containing polymer) in addition to the components contained in each embodiment. For example, in embodiments [1] to [5], a high-fluorine-containing polymer may further be contained. In this specification, the term "solid components" refers to components other than the solvent contained in the composition.

[0035] Next, the components contained in the composition and the optional components will be described in detail. Unless otherwise specified, each component contained in the composition may be used alone or in combination of two or more.

[0036] <Polymer (A)> (First Structural Unit) The first structural unit is a structural unit derived from a maleimide compound and having a protected carboxyl group. Specifically, the first structural unit is represented by the following formula (1): (In formula (1), R １ and R ２ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a fluoromethyl group. １ is a single bond or a divalent organic group. １ is an acid-dissociable group.)

[0037] In the above formula (1), R １ and R ２ is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom, from the viewpoint of copolymerizability of the monomer that provides the first structural unit and easy availability.

[0038] L １ is preferably a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted divalent hydrocarbon group in which a methylene group is substituted with a group containing at least one heteroatom selected from the group consisting of an oxygen atom, a sulfur atom, and a nitrogen atom.

[0039] Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms include a divalent chain hydrocarbon group having 1 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0040] The divalent chain hydrocarbon group having 1 to 20 carbon atoms may be saturated or unsaturated, and may be linear or branched. Examples of the divalent chain hydrocarbon group having 1 to 20 carbon atoms include alkanediyl groups such as methylene group, ethylene group, 1,3-propanediyl group, 1,2-propanediyl group, 1,4-butanediyl group, 1,3-butanediyl group, 1,2-butanediyl group, 1,1-butanediyl group, 2,3-butanediyl group, 1,5-pentanediyl group, 1,4-pentanediyl group, and 1,3-pentanediyl group; alkenediyl groups such as ethenediyl group, propenediyl group, and butenediyl group; and alkynediyl groups such as ethynediyl group, propynediyl group, and butynediyl group. Among these, L １ The divalent chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) is preferably an alkanediyl group, more preferably an alkanediyl group having 1 to 5 carbon atoms, still more preferably a methylene group or an ethylene group, and particularly preferably a methylene group.

[0041] Examples of divalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include divalent groups obtained by removing one hydrogen atom from the aliphatic ring of a monovalent monocyclic alicyclic saturated hydrocarbon group, such as a cyclopentyl group, a cyclohexyl group, a methylcyclopentyl group, an ethylcyclopentyl group, a methylcyclohexyl group, or an ethylcyclohexyl group; divalent groups obtained by removing one hydrogen atom from the aliphatic ring of a monovalent monocyclic alicyclic unsaturated hydrocarbon group, such as a cyclopentenyl group, a cyclohexenyl group, a methylcyclopentenyl group, or a methylcyclohexenyl group; divalent groups obtained by removing one hydrogen atom from the aliphatic ring of a monovalent polycyclic alicyclic saturated hydrocarbon group, such as a norbornyl group, an adamantyl group, or a tricyclodecyl group; and divalent groups obtained by removing one hydrogen atom from the aliphatic ring of a monovalent polycyclic alicyclic unsaturated hydrocarbon group, such as a norbornenyl group, a tricyclodecenyl group, or an indanyl group. Furthermore, when the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms has a polycyclic structure, the polycyclic structure may be any of a fused ring structure, a bridged structure, and a spiro ring structure, or may be a combination of two or more of these. Note that the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms may further have a chain structure in addition to the above-mentioned alicyclic structure.

[0042] Examples of divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include divalent groups in which one hydrogen atom has been removed from the aromatic ring of an aryl group such as a phenyl group, tolyl group, xylyl group, mesityl group, naphthyl group, methylnaphthyl group, anthryl group, methylanthryl group, or indenyl group; and divalent groups in which one hydrogen atom has been removed from the aromatic ring of an aralkyl group such as a benzyl group, phenethyl group, naphthylmethyl group, or anthrylmethyl group. The monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms may further have a chain structure or an alicyclic structure in addition to the aromatic ring structure described above.

[0043] Examples of the group containing at least one heteroatom selected from the group consisting of an oxygen atom, a sulfur atom, and a nitrogen atom include —O—, —CO—, —NH ２ -, -SO-, -SO ２ or a divalent group consisting of a combination thereof.

[0044] Examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, 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, where R is an alkyl group having 1 to 3 carbon atoms), 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 halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, etc.

[0045] From the viewpoint of ease of obtaining raw materials used for synthesizing the monomer that gives the first structural unit, and from the viewpoint of further enhancing the effect of improving the CDU performance and the CDU exposure margin, and suppressing the occurrence of defects, L １ Among the above, is preferably a divalent hydrocarbon group having 1 to 20 carbon atoms, more preferably an alkanediyl group having 1 to 20 carbon atoms, still more preferably an alkanediyl group having 1 to 5 carbon atoms, still more preferably a methylene group or ethylene group, and particularly preferably a methylene group.

[0046] P １The acid-dissociable group represented by the formula "-COOP" is a group that substitutes a hydrogen atom of a carboxy group and is dissociated by the action of an acid. １ " includes, for example, P １ groups each having a tertiary carbon atom, a benzylic carbon atom, or an allylic carbon atom, and bonding to the oxygen atom in the oxycarbonyl group (—COO—) via any of these carbon atoms; groups having an acetal ester structure of a carboxylic acid; and groups having a ketal ester structure of a carboxylic acid.

[0047] High desorption by exposure to light １ A preferred example of the group represented by the formula (p-1) is a structure represented by the following formula (p-1): (In formula (p-1), R １１ R is a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aliphatic heterocyclic group. １２ and R １３ are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic heterocyclic group, or R １２ and R １３ are aligned with each other and R １２ and R １３ represents an alicyclic hydrocarbon structure having 3 to 20 carbon atoms, which is formed together with the carbon atom to which R is bonded. １１ When is a hydrogen atom, R １２ and R １３ or 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 １２ and R １３ are aligned with each other and R １２ and R １３ 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. "*" represents a bond.)

[0048] In the above formula (p-1), R １１ ~R １３Examples 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.

[0049] The monovalent chain hydrocarbon group having 1 to 20 carbon atoms may be saturated or unsaturated, and may be linear or branched. 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. Among these, R １１ ~R １３ The monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) is preferably an alkyl group or an alkenyl group, more preferably an alkyl group having 1 to 4 carbon atoms or an alkenyl group having 2 to 4 carbon atoms.

[0050] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms and the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include L １ Examples of the monovalent aromatic heterocyclic group include a furyl group, a thienyl group, etc.

[0051] R １２ and R １３ are aligned with each other and R １２ and R １３ 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 aliphatic hydrocarbon structures such as a cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cycloheptane structure, and cyclooctane structure; monocyclic unsaturated aliphatic hydrocarbon structures such as cyclopentene and cyclohexene; and polycyclic aliphatic hydrocarbon structures such as a norbornane structure, adamantane structure, tricyclodecane structure, and tetracyclododecane structure.

[0052] R １１ ~R １３When the group represented by the formula (I) has a substituent, examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), a hydroxyl group, an alkoxy group having 1 to 3 carbon atoms, etc.

[0053] P １ Preferably, P has a ring structure. １ When P has a ring structure, the difference in solubility in a developer between the exposed and unexposed areas can be made larger, and the effect of improving the CDU performance and the CDU exposure margin can be further enhanced. １ The ring structure that may be contained in the ring may be any of a saturated aliphatic ring, an unsaturated aliphatic ring, and an aromatic ring, or may be two or more of these.

[0054] The leaving group containing an aromatic ring has an even higher leaving property and can further improve the CDU performance and the CDU exposure margin. １ It is particularly preferred that P has an aromatic ring. Examples of the aromatic ring include aromatic hydrocarbon rings such as a benzene ring and a naphthalene ring; and aromatic heterocyclic rings such as a furan ring and a thiophene ring. １ Of these, a benzene ring is particularly preferred because it is relatively easy to introduce a ring structure into the ring and it can enhance the effect of improving the CDU performance and the CDU exposure margin while suppressing the occurrence of development defects.

[0055] When the first structural unit has an iodine atom, R １ , R ２ , L １ and P １ Any of the R in the formula (1) may have an iodine atom. １ , R ２ , L １ and P １ Two or more of the P in the formula (1) may contain an iodine atom. The P in the formula (1) is preferred in that it can increase the difference in solubility in a developer between an exposed area and an unexposed area while suppressing the occurrence of development defects, and can further enhance the effect of improving the CDU performance and the CDU exposure margin. １In addition, it is preferable that P in the above formula (1) has an iodine atom, in that it is possible to increase the sensitivity of the radiation-sensitive composition and to obtain a radiation-sensitive composition having improved CDU performance and CDU exposure margin. １ It is particularly preferred that the aromatic ring has an iodine atom bonded to it.

[0056] Specific examples of the first structural unit include structural units represented by the following formulas: However, the first structural unit is not limited to these specific examples. (In the formula, R １ and R ２ are each independently a hydrogen atom, a fluorine atom, an iodine atom, a methyl group, or a halogenated methyl group.

[0057] In the polymer (A), the content of the first structural unit 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 structural units contained in the polymer (A). Furthermore, the content of the first structural unit is preferably 90 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less, based on the total amount of structural units contained in the polymer (A). 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 areas can be appropriately increased, thereby improving the CDU performance and CDU exposure margin of the composition. Furthermore, a resist pattern with fewer defects can be obtained.

[0058] (Second structural unit) The second structural unit is a structural unit derived from a radiation-sensitive onium salt, and is typically a structural unit derived from a monomer comprising a radiation-sensitive onium cation and an organic anion. When the present composition does not contain a radiation-sensitive onium salt (B), the polymer (A) contains the second structural unit. In this case, the present composition satisfies Requirement 1.

[0059] The second structural unit is thought to liberate an organic anion when the radiation-sensitive onium cation decomposes under the action of radiation, and the organic anion thus liberated bonds with hydrogen abstracted from components contained in the composition (e.g., the radiation-sensitive acid generator, the acid diffusion controller, the solvent, etc.), thereby generating an acid derived from the organic anion. Examples of the organic anion include a sulfonate anion and a carboxylate anion.

[0060] When the organic anion in the second structural unit is a sulfonate anion, the second 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 second structural unit is a carboxylate anion, the second 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.

[0061] The second 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. 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 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 further improve the CDU performance of the present composition, it is preferable that the second structural unit be bonded to the main chain of the polymer via a linking group, and that the organic anion be a sulfonate anion (—SO ３ － ) is more preferably bonded to the main chain of the polymer via a linking group.

[0062] The radiation-sensitive onium cation in the second 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, at least one of an iodo group, a fluoro group, and a fluoroalkyl group is bonded to the aromatic ring bonded to the aromatic ring. The fluoroalkyl group is preferably a trifluoromethyl group.

[0063] The second structural unit may have an iodine atom, which can contribute to further increasing the sensitivity of the present composition. When the second structural unit has an iodine atom, it is preferable that the second structural unit has an aromatic ring to which the iodine atom is bonded.

[0064] Specific examples of the second structural unit include structural units represented by the following formulas: However, the second 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.

[0065] When the polymer (A) contains the second structural unit, the content of the second structural unit in the polymer (A) is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more, based on the total amount of structural units contained in the polymer (A). Furthermore, the content of the second structural unit in the polymer (A) is preferably 25 mol% or less, more preferably 20 mol% or less, based on the total amount of structural units contained in the polymer (A). By setting the content of the second structural unit within the above range, the effect of improving the sensitivity of the composition by introducing the second structural unit can be sufficiently obtained.

[0066] Examples of the structural unit (other structural unit) that the polymer (A) may contain include the third structural unit, fourth structural unit, fifth structural unit, and sixth structural unit shown below.

[0067] (Third structural unit) The polymer (A) may further contain a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring (referred to as the "third structural unit"). When the polymer (A) has a hydroxyl group bonded to the aromatic ring, the CDU performance of the composition can be further improved, and the effect of suppressing dissolution of unexposed areas into a developer can be highly effective, sufficiently reducing defects. Furthermore, the polymer (A) containing the third structural unit can be preferably used in pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV. Note that the third structural unit differs from the second structural unit in that it does not have an onium salt structure.

[0068] A preferred example of the third 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, —O—, —COO—, or —CONH—. １ is a group obtained by removing (n1+n2+1) hydrogen atoms from an aromatic ring. ４ is a substituent different from a hydroxyl 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.)

[0069] 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 third structural unit. ２ is preferably a single bond, since this can suppress variation in the solubility of the polymer (A) in a developer, contribute to the effect of improving the CDU performance and CDU exposure margin of the composition, and enable a resist pattern with further reduced defect occurrence to be obtained.

[0070] A １is a group obtained by removing (n1+n2+1) hydrogen atoms from an aromatic ring. The aromatic ring is preferably an aromatic hydrocarbon ring, such as a benzene ring, a naphthalene ring, an anthracene ring, or a phenanthrene ring. From the viewpoint of ease of synthesis of a monomer that provides a third structural unit and sensitivity, A １ The aromatic ring contained in is preferably a benzene ring or a naphthalene ring, more preferably a benzene ring.

[0071] The position of the hydroxyl group bonded to the aromatic ring is not particularly limited. For example, when the third structural unit has a hydroxyl group bonded to a benzene ring, the bonding position of the hydroxyl group on the benzene ring in the third structural unit is not particularly limited. ２ The position of the hydroxyl group bonded to the benzene ring in the third structural unit may be ortho-, meta- or para- to the other group (L). Intermolecular hydrogen bonding effectively works, contributing to a high Tg, and as a result, the CDU performance of the present composition can be improved. ２ ) is preferably in the meta or para position relative to the alkyl group.

[0072] R ４ R may be any group other than a hydroxyl group. ４ Specific examples of the formula (1) include L １ Among the groups exemplified as the substituent that may be possessed by n1, groups other than a hydroxyl group can be mentioned. 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.

[0073] Specific examples of the third structural unit include structural units represented by the following formulae: However, the third 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.

[0074] In the polymer (A), the content of the third structural unit 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 structural units contained in the polymer (A). Furthermore, the content of the third structural unit is preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 60 mol% or less, based on the total amount of structural units contained in the polymer (A). By setting the content of the third structural unit within the above range, the CDU performance and CDU exposure margin of the composition can be improved, and a resist pattern with fewer defects can be obtained.

[0075] (Fourth structural unit) The fourth structural unit is a structural unit having an acid-dissociable group. However, the fourth structural unit is different from the first structural unit. In the present composition, the fourth structural unit may be introduced into the polymer (A) together with the first structural unit in order to adjust the sensitivity of the polymer (A) and its solubility in a developer.

[0076] The acid-dissociable group of the fourth structural unit is a group that substitutes a hydrogen atom of an acid group such as a carboxyl group or a hydroxyl group, and can be a group that is eliminated by the action of an acid.However, in this specification, among the structural units different from the structural unit represented by the above formula (1), the structural unit that has an acid-dissociable group and a hydroxyl group bonded to an aromatic ring is classified as the third structural unit.That is, the fourth structural unit is different from the third structural unit in that it does not have a hydroxyl group bonded to an aromatic ring.In addition, the fourth structural unit is different from the second structural unit in that it does not have an onium salt structure.

[0077] Specific examples of the fourth structural unit include a structural unit represented by the following formula (4-1) (hereinafter also referred to as "structural unit (4a)"), a structural unit represented by the following formula (4-2) (hereinafter also referred to as "structural unit (4b)"), and a structural unit represented by the following formula (4-3) (hereinafter also referred to as "structural unit (4c)"). (In formula (4-1), 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. ３１is 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 aligned with each other and 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 ３３ or 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 aligned with each other and 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 (4-2), 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 other than a hydroxyl group. g2 is an integer of 0 to 4. In formula (4-3), 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 other than a hydroxyl group. g3 is an integer of 0 to 4.

[0078] In the above formula (4-1), R ３０ In view of the copolymerizability of the monomer that gives the structural unit (4a), 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 (4b). ３０ is preferably a hydrogen atom or a methyl group. ４ Or L in formula (4-3) ５ is preferably a single bond, —COO— or —CONH—.

[0079] L in the above formula (4-1) ３ The divalent chain organic group represented by the formula (I) includes a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, a methylene group contained in the chain or branched saturated hydrocarbon group being a heteroatom-containing group (for example, -O-, -S-, -CO-, -COO-, -NH-, -NHCO-, -SO ２ -), and a divalent group having 2 to 20 carbon atoms. ３ Specific examples of the divalent alicyclic hydrocarbon group represented by the formula (1) include L １ Examples of the groups include the same groups as those exemplified in the description of 1.

[0080] R in the above formulas (4-1) to (4-3) ３１ ~R３３ , 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 (p-1) 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. Specific examples of these include R １１ ~R １３ Examples of the monovalent aromatic heterocyclic group include the same groups as those exemplified in the description of 1. Examples of the monovalent aromatic heterocyclic group include a furyl group and a thienyl group.

[0081] R ３２ and R ３３ are aligned with each other and 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 aligned with each other and R ３８ and R ３９ The alicyclic hydrocarbon structure having 3 to 20 carbon atoms formed together with the carbon atom to which R is bonded includes R １１ ~R １３ The same structure as that exemplified in the description of 1. can be used.

[0082] R in the above formula (4-2) ２８ , R in the above formula (4-3) ２９ Specific examples of the formula (1) include L １ Examples of the substituent that may be possessed by g2 include the same groups as those exemplified above. Each of g2 and g3 is preferably 0 to 2.

[0083] Specific examples of the fourth structural unit include structural units represented by the following formula: ３０ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, however, the fourth structural unit is not limited to the specific examples below.

[0084] Structural unit (4a)

[0085] Structural unit (4b)

[0086] Structural unit (4c)

[0087] In the polymer (A), the content of the fourth structural unit is preferably 70 mol % or less, more preferably 50 mol % or less, and even more preferably 30 mol % or less, based on the total amount of structural units contained in the polymer (A). By setting the content of the fourth structural unit within the above range, the difference in dissolution rate in a developer between an exposed portion and an unexposed portion can be sufficiently increased, and the CDU performance of the composition can be further improved.

[0088] (Fifth Structural Unit) The fifth structural unit is a structural unit having a lactone structure, a cyclic carbonate structure, a sultone structure, or a ring structure that combines two or more of these, and is a structural unit different from the first to fourth structural units.

[0089] Specific examples of the fifth structural unit include structural units represented by the following formulas: However, the fifth structural unit is not limited to these specific examples. (In the formula, R Ｌ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0090] The content of the fifth structural unit in the polymer (A) is preferably 20 mol % or less, more preferably 15 mol % or less, and even more preferably 10 mol % or less, based on the total amount of structural units contained in the polymer (A).

[0091] (Sixth Structural Unit) The sixth structural unit may further include a structural unit having an alcoholic hydroxyl group (excluding the first to fifth structural units). By introducing the sixth structural unit into the polymer (A), the effect of suppressing development defects can be further enhanced when a resist pattern is formed using the present composition. Here, in this specification, an "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).

[0092] The sixth structural unit is preferably a structural unit derived from an unsaturated monomer having an alcoholic hydroxyl group. The structure of the unsaturated monomer that provides the sixth structural unit is not particularly limited. Specific examples of the sixth structural unit include structural units represented by the following formulas. However, the sixth structural unit is not limited to these specific examples. (In the formula, R Ａ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0093] In the polymer (A), the content of the sixth structural unit is preferably 20 mol % or less, and more preferably 10 mol % or less, based on the total amount of structural units contained in the polymer (A).

[0094] In addition to the above, other structural units contained in the polymer (A) 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), a structural unit derived from vinylnaphthalene, a structural unit derived from n-pentyl(meth)acrylate), and a structural unit derived from (meth)acrylic acid. 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.

[0095] The weight average molecular weight (Mw) of the polymer (A) 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 (A) 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 (A) within the above range, the coatability of the composition can be improved and development defects can be sufficiently suppressed, which is advantageous.

[0096] The ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the polymer (A) 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 (A) is usually 1.0 or more.

[0097] The polymer (A) is preferably blended into the composition as at least a part of the base resin, and the content of the polymer (A) 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.

[0098] The polymer (A) can be synthesized, for example, by polymerizing monomers that provide each structural unit in an appropriate solvent using a known radical polymerization initiator. Examples of the radical polymerization initiator include azo radical initiators (e.g., azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile)), peroxide radical initiators (e.g., benzoyl peroxide), and the like. Examples of the solvent used in the polymerization include linear alkanes, cycloalkanes, aromatic hydrocarbons, halogenated hydrocarbons, saturated carboxylic acid esters, ketones, ethers, and alcohols. The reaction temperature in the polymerization is preferably 40 to 150°C, more preferably 50 to 120°C. The reaction time is preferably 1 to 48 hours, more preferably 2 to 24 hours.

[0099] Here, with the trend toward ever-higher definition of resist patterns, it is important that not only is CDU performance good, but also that the change in CDU performance due to differences in exposure conditions is small and that the exposure margin (CDU exposure margin) is wide. Furthermore, by incorporating an iodine-containing component into the radiation-sensitive composition, the sensitivity of the radiation-sensitive composition can be increased, contributing to further miniaturization of the resist pattern. However, there is a concern that defects may occur in the resist pattern due to the low solubility of the iodine-containing component in the developer. In this regard, by incorporating a polymer (A) containing a first structural unit into the radiation-sensitive composition, it is possible to increase the Tg of the polymer component in the radiation-sensitive composition while generating acid groups in the first structural unit by exposure. This leads to a greater difference in solubility in the developer between the exposed and unexposed portions of the resist film, which is thought to result in enhanced improvements in CDU performance and CDU exposure margin, as well as suppression of defects.

[0100] In particular, when a third structural unit (more preferably a structural unit derived from a styrene compound) is introduced into the polymer (A) together with the first structural unit, it is believed that the alternating copolymerization of the first structural unit and the third structural unit can suppress uneven distribution of the first structural unit within the molecule. This can suppress variation in the solubility of the polymer (A), and as a result, it is believed that the CDU performance, CDU exposure margin, and defect suppression properties can be highly improved in a balanced manner. However, the above is merely speculation and does not limit the present invention.

[0101] <Radiation-sensitive onium salt (B)> From the viewpoint of ensuring high sensitivity and CDU performance, the present composition preferably contains a radiation-sensitive onium salt (B). In particular, by containing at least an acid diffusion controller as the radiation-sensitive onium salt (B), the present composition can further enhance the effect of expanding the CDU exposure margin.

[0102] Radiation-Sensitive Acid Generator There are no particular restrictions on the type of acid generator to be incorporated into the composition, and any known radiation-sensitive acid generator used in resist pattern formation can be used as appropriate. The acid generator is preferably a compound that generates, under the above-mentioned normal conditions, an acid in the composition that is more acidic than the acid generated by the acid diffusion controller (preferably a strong acid such as a sulfonic acid, imidic acid, or methide acid), thereby inducing dissociation of the acid-dissociable group.

[0103] From the viewpoint of increasing the sensitivity of the present composition and forming a resist film with excellent lithography performance, the acid generator preferably has a sulfonium cation, a tetrahydrothiophenium cation, or an iodonium cation as the radiation-sensitive onium cation, and more preferably has an arylsulfonium cation or an aryliodonium cation.

[0104] Specific examples of the radiation-sensitive onium cation contained in the acid generator include cations represented by the following formula (4), cations represented by the following formula (5), and cations represented by the following formula (6). (In formula (5), R １ａ and R ２ａ are each independently a monovalent substituent, or R １ａ and R ２ａ are combined together to represent a single bond or a divalent group connecting the rings to which they are attached. ３ａ is a monovalent substituent. a1 and a2 are each independently an integer of 0 to 5. a3 is an integer of 0 to (2×r+5). r is 0 or 1. In formula (6), R ４ａ and R ５ａ are each independently a monovalent substituent. a4 and a5 are each independently an integer of 0 to 5. In formula (7), a6 is an integer of 0 to 7. When a6 is 1, R ６ａ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen group. ６ａ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen group, or a plurality of R ６ａWhen two of the groups are combined together, they represent a ring structure having 4 to 20 ring members, which is formed together with the carbon atoms to which they are attached. a7 is an integer of 0 to 6. When a7 is 1, R ７ａ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen group. ７ａ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen group, or a plurality of R ７ａ Two of these are combined together to form a ring structure having 3 to 20 ring members together with the carbon atoms to which they are attached. t1 is an integer of 0 to 3. R ８ａ is a single bond or a divalent organic group having 1 to 20 carbon atoms. t2 is 0 or 1.

[0105] In the above formulas (5) and (6), R １ａ , R ２ａ , R ３ａ , R ４ａ and R ５ａ (Hereinafter referred to as “R １ａ ~R ５ａ ") include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted cycloalkyloxy group, an ester group, an alkylsulfonyl group, a cycloalkylsulfonyl group, a hydroxy group, a carboxy group, a cyano group, and a nitro group.

[0106] R １ａ ~R ５ａ The alkyl group represented by the formula (I) may be linear or branched. The alkyl group preferably has 1 to 10 carbon atoms. １ａ ~R ５ａ The alkyl group represented by the formula (I) preferably has 1 to 5 carbon atoms, and more preferably is a methyl group, an ethyl group, an n-butyl group, or a t-butyl group. １ａ ~R ５ａSpecific examples of when is an alkoxy group include groups having the alkyl group exemplified above in the alkyl group moiety that constitutes the alkoxy group. The alkoxy group is preferably a methoxy group, an ethoxy group, an n-propoxy group, or an n-butoxy group.

[0107] R １ａ ~R ５ａ The cycloalkyl group represented by the formula (I) may be either monocyclic or polycyclic. Among these, examples of monocyclic cycloalkyl groups include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. Examples of polycyclic cycloalkyl groups include a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group. R １ａ ~R ５ａ Specific examples of when R is a cycloalkyloxy group include groups having the above-mentioned cycloalkyl groups in the cycloalkyl group moiety constituting the cycloalkyloxy group. １ａ ~R ５ａ The cycloalkyloxy group represented by the following formula is preferably a cyclopentyloxy group or a cyclohexyloxy group.

[0108] R １ａ ~R ５ａ When has a substituent, examples of the substituent include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, and an alkoxy group having 1 to 5 carbon atoms.

[0109] R １ａ ~R ５ａ When R is an ester group (—COOR), examples of the hydrocarbon portion (R) of the ester group include the substituted or unsubstituted alkyl groups or substituted or unsubstituted cycloalkyl groups exemplified above. １ａ ~R ５ａ is an ester group, R １ａ ~R ５ａ is preferably a methoxycarbonyl group, an ethoxycarbonyl group, or an n-butoxycarbonyl group. １ａ ~R ５ａWhen R is an alkylsulfonyl group, examples of the alkyl group moiety constituting the alkylsulfonyl group include the substituted or unsubstituted alkyl groups exemplified above. １ａ ~R ５ａ When is a cycloalkylsulfonyl group, the cycloalkyl group moiety constituting the cycloalkylsulfonyl group includes the substituted or unsubstituted cycloalkyl groups exemplified above.

[0110] R １ａ and R ２ａ When these are combined together to represent a divalent group connecting the rings to which they are bonded, examples of the divalent group include -COO-, -OCO-, -CO-, -O-, -SO-, and -SO ２ -, -S-, an alkanediyl group having 1 to 3 carbon atoms, an alkenediyl group having 2 or 3 carbon atoms, -O-, -S-, -COO-, -OCO-, -CO-, -SO-, or -SO between the carbon-carbon bonds of the ethylene group ２ Among these, groups having R １ａ and R ２ａ is preferably a single bond connecting the rings, or forms —O— or —S—.

[0111] Each of a1, a2, and a3 is preferably an integer of 0 to 2. １ａ , R ２ａ and R ３ａ At least one of a4 and a5 is preferably a fluorine atom, an iodine atom, or a trifluoromethyl group. Each of a4 and a5 is preferably an integer of 0 to 2. ４ａ and R ５ａ At least one of the groups is preferably a fluorine atom, an iodine atom, or a trifluoromethyl group.

[0112] In the above formula (7), R ６ａ and R ７ａ The monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) includes a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, -OR ｋ , -COOR ｋ , —O—CO—R ｋ , -O-Rｋｋ -COOR ｋ , -R ｋｋ -CO-R ｋ , -OSO ２ -R ｋ or -SO ２ -R ｋ etc. ｋ is a monovalent hydrocarbon group having 1 to 10 carbon atoms. ｋｋ is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms. Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include the same groups as those exemplified in the above formula (p-1). ６ａ and R ７ａ In the above, examples of the substituents that substitute hydrogen atoms of the hydrocarbon group include the above R １ａ ~R ５ａ Examples of the substituents that the group represented by the formula (R) has include the same groups as those exemplified above. ８ａ Examples of the divalent organic group represented by the formula: ６ａ and R ７ａ Examples of such groups include groups in which one hydrogen atom has been removed from the monovalent organic groups having 1 to 20 carbon atoms exemplified above.

[0113] R ６ａ and R ７ａ is a linear or branched monovalent alkyl group, a monovalent fluoroalkyl group, a monovalent aromatic hydrocarbon group, or —OSO ２ -R ｋ or -SO ２ -R ｋ a6 is preferably an integer of 0 to 2, more preferably 0 or 1. a7 is preferably an integer of 0 to 2, more preferably 0 or 1. t2 is preferably 0. t1 is preferably 2 or 3.

[0114] Specific examples of the radiation-sensitive onium cation include cations represented by the following formulas: However, the radiation-sensitive onium cation is not limited to these specific examples.

[0115] The organic anion contained in the acid generator is not particularly limited. In terms of increasing the sensitivity of the present composition, a sulfonate anion, an imide anion, or a methide anion is preferred. For example, specific examples of sulfonate anions include anions represented by the following formula:

[0116] When an acid generator is incorporated into the composition, the content of the acid generator is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, per 100 parts by mass of polymer (A), from the viewpoint of fully obtaining the effect of improving sensitivity due to the incorporation of the acid generator. Furthermore, from the viewpoint of suppressing the occurrence of development defects due to the acid generator, the content of the acid generator is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, per 100 parts by mass of polymer (A).

[0117] Acid Diffusion Controller: The acid diffusion controller is a component that can suppress acid-induced chemical reactions in unexposed areas by inhibiting the diffusion of acid generated in the resist film upon exposure of the composition. By incorporating such an acid diffusion controller in the composition, the CDU performance of the composition can be improved and the CDU exposure margin can be expanded. The acid diffusion controller (hereinafter also referred to as "photodegradable base") having a radiation-sensitive onium cation and an organic anion that is the conjugate base of the acid is preferably an onium salt that generates a carboxylic acid, sulfonic acid, or sulfonamide upon exposure. Furthermore, in terms of forming a resist film with superior lithography performance, an onium salt having a sulfonium cation or an iodonium cation is preferably used as the photodegradable base.

[0118] Specific examples of the radiation-sensitive onium cation contained in the photodecomposable base include the same onium cations as those exemplified as the radiation-sensitive onium cation that may be contained in the acid generator.

[0119] Examples of the organic anion contained in the photodegradable base include anions represented by the following formula:

[0120] 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 (A) from the viewpoint of sufficiently improving the sensitivity, CDU performance, and CDU exposure margin. Furthermore, from the viewpoint of suppressing the occurrence of development 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 (A).

[0121] 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 acid generator contained in the composition and the monomer that provides the second structural unit in the polymer (A). 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 acid generator contained in the composition and the monomer that provides the second structural unit in the polymer (A). By setting the content of the acid diffusion controller within the above range, the CDU performance of the composition can be further improved.

[0122] <Other Components> The present composition may further contain components (hereinafter also referred to as "other components") other than the polymer (A) and the radiation-sensitive onium salt (B). Examples of other components include the following components.

[0123] (High-Fluorine Content Polymer) The high-fluorine content polymer (hereinafter also referred to as "polymer (F)") is a polymer having a higher mass content of fluorine atoms than polymer (A). Polymer (F) is contained in the radiation-sensitive composition as, for example, a water-repellent additive or a modifier that improves the lithography performance, etc., of the composition.

[0124] The fluorine atom content of the polymer (F) is not particularly limited as long as it is larger than that of the polymer (A). 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.

[0125] Examples of the fluorine atom-containing structural unit (hereinafter also referred to as "structural unit (f)") contained in polymer (F) include the structural unit (fa) and structural unit (fb) shown below. Polymer (F) may contain either the structural unit (fa) or the structural unit (fb) as the structural unit (f), or may contain both the structural unit (fa) and the structural unit (fb).

[0126] Structural Unit (fa) The structural unit (fa) is a structural unit represented by the following formula (9-1): By adjusting the content of the structural unit (fa) in the polymer (F), the fluorine atom content of the polymer (F) can be adjusted. (In formula (9-1), R Ｃ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, —COO—, or —SO ２ -O-NH-, -CONH- or -O-CO-NH-. Ｅ is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0127] In the above formula (9-1), R C From the viewpoint of copolymerizability of the monomer that provides the structural unit (fa), G is preferably a hydrogen atom or a methyl group, and more preferably a methyl group. From the viewpoint of copolymerizability of the monomer that provides the structural unit (fa), G is preferably a single bond or —COO—, and more preferably —COO—.

[0128] R ＥExamples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (R) include a linear or branched alkyl group having 1 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms. E Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include monocyclic or polycyclic alicyclic hydrocarbon groups having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms. Ｅ is preferably a monovalent fluorinated chain hydrocarbon group, more preferably a monovalent fluorinated alkyl group, and even more preferably a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group or a 5,5,5-trifluoro-1,1-diethylpentyl group.

[0129] When the polymer (F) has the structural unit (fa), the content of the structural unit (fa) is preferably 30 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more, based on all structural units constituting the polymer (F). The content of the structural unit (fa) is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less, based on all structural units constituting the polymer (F). By setting the content of the structural unit (fa) within the above range, the mass content of fluorine atoms in the polymer (F) can be more appropriately adjusted, further promoting uneven distribution of fluorine atoms in the surface layer of the resist film. This can further improve the water repellency of the resist film during immersion exposure.

[0130] Structural Unit (fb) The structural unit (fb) is a structural unit represented by the following formula (9-2): By including the structural unit (fb), the polymer (F) has improved solubility in an alkaline developer, which can further suppress the occurrence of development defects. (In formula (9-2), R Ｆ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. ５９ is a hydrocarbon group having 1 to 20 carbon atoms and a valence of (s+1), or R ６０is a group in which an oxygen atom, a sulfur atom, —NR′—, a carbonyl group, —CO—O—, or —CO—NH— is bonded to the terminal of the R ６０ is a single bond or a divalent organic group having 1 to 20 carbon atoms. １２ represents a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms. １１ represents an oxygen atom, —NR″—, —CO—O—*, or —SO ２ -O-*. R" is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. "*" is R ６１ The binding site that binds to R ６１ is a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms. s is an integer of 1 to 3. However, when s is 2 or 3, multiple R ６０ , X １２ , A １１ and R ６１ are the same or different.)

[0131] The structural unit (fb) is divided into a structural unit having an alkali-soluble group and a structural unit having a group that dissociates under the action of an alkali to increase the solubility in an alkali developer (hereinafter, also simply referred to as an "alkali-dissociable group").

[0132] When the structural unit (fb) has an alkali-soluble group, R ６１ is a hydrogen atom, and A １１ represents an oxygen atom, —COO—*, or —SO ２ O-*. "*" is R ６１ The binding site is indicated by X. １２ represents a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. １１ is an oxygen atom, X １２ Is A １１ is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which R is bonded. ６０ is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R ６０ , X １２ , A １１ and R ６１When the structural unit (fb) has an alkali-soluble group, it is possible to increase the affinity for an alkali developer and suppress development defects.

[0133] When the structural unit (fb) has an alkali-dissociable group, R ６１ is a monovalent organic group having 1 to 30 carbon atoms, and A １１ is an oxygen atom, —NR″—, —COO—*, or —SO ２ O-*. "*" is R ６１ The binding site is indicated by X. １２ is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ６０ is a single bond or a divalent organic group having 1 to 20 carbon atoms. １１ -COO-* or -SO ２ If O-*, then X １２ or R ６１ Is A １１ A has a fluorine atom on the carbon atom bonded to or adjacent to the carbon atom. １１ is an oxygen atom, X １２ or R ６０ is a single bond, and R ５９ is a hydrocarbon group having 1 to 20 carbon atoms. ６０ A carbonyl group is bonded to the end of the R ６１ is an organic group having a fluorine atom. When s is 2 or 3, a plurality of R ６０ , X １２ , A １１ and R ６１ are the same or different from each other. When the structural unit (fb) has an alkali dissociable group, the surface of the resist film changes from hydrophobic to hydrophilic in the alkali development step. This can increase the affinity to the developer and more efficiently suppress development defects. Examples of the structural unit (fb) having an alkali dissociable group include A １１ is -COO-*, and R ６１ or X １２ It is particularly preferred that both of them have a fluorine atom.

[0134] When polymer (F) has structural unit (fb), the content of structural unit (fb) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more, based on all structural units constituting polymer (F). Furthermore, the content of structural unit (fb) is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less, based on all structural units constituting polymer (F). By setting the content of structural unit (fb) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0135] In addition to the structural unit (fa) and the structural unit (fb), the polymer (F) may also include a structural unit having an acid-dissociable group or a structural unit having an alicyclic hydrocarbon structure represented by the following formula (10) (hereinafter also referred to as "structural unit (g)"). (In the above formula (10), R Ｇ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｇ２ is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0136] In the above formula (10), R Ｇ２ The monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (1) is １ The same groups as those exemplified in the description of the above may be mentioned.

[0137] When polymer (F) contains a structural unit represented by formula (10), the content of the structural unit is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, based on all structural units constituting polymer (F). The content of the structural unit represented by formula (10) is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less, based on all structural units constituting polymer (F).

[0138] The Mw of the polymer (F) measured by GPC is preferably 1,000 or more, more preferably 3,000 or more, and even more preferably 4,000 or more. The Mw of the polymer (F) is preferably 50,000 or less, more preferably 30,000 or less, and even more preferably 20,000 or less. The dispersity (Mw / Mn) of the polymer (F) measured by GPC, which is expressed as the ratio of Mn to Mw, is preferably 1.0 or more and 5.0 or less, and more preferably 1.0 or more and 3.0 or less.

[0139] 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, relative to 100 parts by mass of polymer (A). The content of polymer (F) is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, relative to 100 parts by mass of polymer (A).

[0140] (Solvent) The solvent is preferably a solvent capable of dissolving or dispersing the components to be blended in the composition, and an organic solvent can be preferably used. Specific examples of the solvent include alcohols, ethers, ketones, amides, esters, and hydrocarbons.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] Other Optional Components The composition may further contain other components (hereinafter also referred to as "other optional components") other than the polymer (F) and the solvent. Examples of the other optional components include surfactants, alicyclic skeleton-containing compounds (e.g., 1-adamantanecarboxylic acid, 2-adamantanone, t-butyl deoxycholate, etc.), sensitizers, and uneven distribution promoters.

[0146] <Method for producing radiation-sensitive composition> The present composition can be produced, for example, by mixing components such as the polymer (A) and, if necessary, a solvent 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, it is possible to improve the coatability and form a good resist pattern shape, which is advantageous.

[0147] 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.

[0148] <<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 a "coating step"), a step of exposing the resist film obtained by the coating step (hereinafter also referred to as an "exposure step"), and a step of developing the resist film exposed by the exposure step (hereinafter also referred to as a "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 that has good sensitivity, good CDU, and good resolution. Each step will be described below.

[0149] [Coating Step] In the coating step, the present 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, for example, silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective coating, such as that disclosed in JP-A-59-93448, may be formed on the substrate. Examples of methods for applying the present 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.

[0150] [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.

[0151] 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 (A) containing a second 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.

[0152] [Development Step] In the development 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 development method in the development step may be alkali development or organic solvent development.

[0153] 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.

[0154] 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).

[0155] <Polymer and Compound> The present disclosure provides a polymer (i.e., polymer (A1)) that includes a structural unit represented by formula (1) and has an iodine atom. Polymer (A1) makes it possible to obtain a radiation-sensitive composition that can form a resist pattern that has excellent CDU performance, a wide CDU exposure margin, and few defects. For details about polymer (A1), the description of polymer (A) is incorporated herein by reference.

[0156] The present disclosure also provides a compound represented by the following formula (2): The compound represented by the following formula (2) can be preferably used as at least a part of the monomers constituting the polymer used in forming a resist pattern. (In formula (2), R １ and R ２ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a fluoromethyl group. １ is a single bond or a divalent organic group. １Ａ is an acid-dissociable group having an iodine atom.

[0157] In the above formula (2), R １ , R ２ and L １ are R in the above formula (1), １ , R ２ and L １ It is synonymous with P. １Ａ The details of P in the above formula (1) １ Specific and preferred examples of the groups having an iodine atom shown in the description of the above are also applicable.

[0158] The compound represented by the formula (2) can be synthesized by appropriately combining conventional methods in organic chemistry. As an example of a method for synthesizing the compound represented by the formula (2), a carboxyl group-containing compound is used as a starting material, and the carboxyl group is converted into a compound represented by the formula (2) by the following scheme: １ and then deprotecting the compound by heating. However, the synthesis method of the compound represented by formula (2) is not limited to the above.

[0159] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the following examples, "parts" and "%" are by mass unless otherwise specified.

[0160] The methods for measuring various physical properties in the examples and comparative examples are as follows. [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] Using Tosoh GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL), the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were measured 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 amount: 100 μL, column temperature: 40° C., and detector: differential refractometer. The dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn. [ １３ C-NMR analysis of polymer １３ C-NMR analysis was carried out using a nuclear magnetic resonance spectrometer (JNM-Delta400 manufactured by JEOL Ltd.).

[0161] 1. Synthesis of Monomers [Synthesis Example A-1: ​​Synthesis of Compound (A-1)] Compound (A-1) was synthesized according to the following synthesis scheme.

[0162] Compound (Z-1) (60 mmol), t-butyl alcohol (50 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC.HCl) (55 mmol), and methylene chloride (120 mL) were added to a reaction vessel and stirred at room temperature. After 30 minutes, 4-dimethylaminopyridine (DMAP) (25 mmol) was added, followed by stirring at 40°C for 7 hours. After that, aqueous hydrochloric acid was added, followed by extraction with methylene chloride. The resulting organic layer was washed with water and dried over sodium sulfate. The solvent was then distilled off, and the resulting mixture was purified by column chromatography to obtain compound (Z-2). Subsequently, compound (Z-2) (45 mmol) and toluene (250 mL) were added to a reaction vessel and stirred for 7 hours while heating and refluxing. The mixture was returned to room temperature, the solvent was distilled off from the filtrate, and compound (A-1) was obtained in good yield by purification by recrystallization.

[0163] [Synthesis Examples A-2 to A-55: Synthesis of Monomer (A-2) to Monomer (A-55)] Compounds represented by the following formulas (A-2) to (A-55) were synthesized in the same manner as in Synthesis Example A-1, except that the raw materials and precursors were appropriately changed.

[0164] 2. [A] Polymer Synthesis A copolymerization reaction was carried out by combining each of the monomers. During the polymerization, the compounds represented by the above formulas (A-1) to (A-55) were used as monomers that provide the first structural unit. Of the monomers used in the synthesis of the polymer, the structures of the monomers other than the monomer that provides the first structural unit are shown below.

[0165] Synthesis Examples 1 to 66: Synthesis of Polymers (P-1) to (P-61) and (CP-1) to (CP-5)] The monomers listed in Tables 1 and 2 were combined and copolymerized in 1-methoxy-2-propanol (200 parts by mass relative to the total amount of monomers) as a solvent. 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, then filtered off and dissolved in 1-methoxy-2-propanol (300 parts by mass). The resin was coagulated by dropping the mixture into 500 parts by mass of water, and the resulting solid was filtered off. The mixture was dried at 50°C for 12 hours to obtain white powdery polymers (P-1) to (P-61) and (CP-1) to (CP-5). The amounts of the monomers used that give the structural units of the resulting polymer, as well as the Mw and Mw / Mn values ​​of the polymer, are shown in Tables 1 and 2.

[0166]

[0167]

[0168] 3. Preparation and Evaluation of Radiation-Sensitive Composition <Preparation of Radiation-Sensitive Composition> The radiation-sensitive acid generators, acid diffusion controllers, and solvents used in the preparation of the radiation-sensitive compositions are shown below.

[0169] <[B1] Radiation-sensitive Acid Generator> Compounds represented by the following formulae (J-1) to (J-12):

[0170] <[B2] Acid Diffusion Controller> Compounds represented by the following formulae (K-1) to (K-8)

[0171] <[C] Solvent> S-1: Propylene glycol monomethyl ether acetate S-2: Propylene glycol monomethyl ether

[0172] Example 1 100 parts by mass of (P-1) as a polymer, 60 parts by mass of (J-7) as a radiation-sensitive acid generator, (K-1) as an acid diffusion controller in an amount of 55 mol % relative to the radiation-sensitive acid generator (J-7), and 1,500 parts by mass of (S-1) and 5,500 parts by mass of (S-2) as organic solvents were blended and mixed, and the mixture was filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive composition (R-1).

[0173] [Examples 2 to 81 and Comparative Examples 1 to 6] Radiation-sensitive compositions (R-2) to (R-81) and (CR-1) to (CR-6) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Tables 3 and 4 below were used.

[0174]

[0175]

[0176] <Formation of Resist Pattern> Each of the radiation-sensitive compositions (R-1) to (R-81) and (CR-1) to (CR-6) prepared above was applied to the surface of a 12-inch silicon wafer on which a 20-nm-thick underlayer film (AL412 (Brewer Science)) had been formed, using a spin coater (CLEAN TRACK ACT12, 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 30-nm-thick resist film. This resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3300," ASML, NA=0.33, illumination conditions: Conventional s=0.89). The resist film was then post-exposure baked (PEB) at 100°C for 60 seconds. Next, development was carried out using a 2.38 wt % aqueous solution of TMAH at 23° C. for 30 seconds to form a positive-type 50 nm pitch, 25 nm contact hole pattern.

[0177] <Evaluation> Each of the resist patterns formed above was measured according to the methods below to evaluate the CDU performance, CDU exposure margin, and number of development defects (defect suppression ability) of each radiation-sensitive composition. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the resist patterns. The evaluation results are shown in Tables 5 and 6 below.

[0178] [CDU Performance] The exposure dose was varied, and the exposure dose required to form the 25 nm contact hole pattern was designated as the optimal exposure dose. Separately, a 25 nm contact hole pattern was formed using the optimal exposure dose. The formed resist pattern was observed from above using the scanning electron microscope described above. Hole diameter variation was measured at a total of 600 points, and a 3 sigma value was calculated from the distribution of the measured values. This 3 sigma value was designated as CDU (nm). The smaller the CDU value, the smaller the long-period hole diameter variation and the better the result. CDU was rated as "A" (very good) when it was less than 2.4 nm, "B" (good) when it was 2.4 nm or more and 4.0 nm or less, and "C" (poor) when it exceeded 4.0 nm.

[0179] [Exposure Margin for CDU Performance (CDU Exposure Margin)] A 25 nm contact hole pattern was formed by irradiating with an exposure dose around the optimum exposure dose. The formed resist pattern was observed from above using a scanning electron microscope (Hitachi High-Tech Corporation's "CG-5000"), and a total of 800 hole diameters were measured at random points. The CD (Critical Dimension) range in which the CDU value was 3.0 nm or less was taken as the CDU exposure margin. The wider the CDU exposure margin, the better the lithography performance. A CDU exposure margin of 10 nm or more was evaluated as "A" (very good), a CDU exposure margin of less than 10 nm but exceeding 5.0 nm was evaluated as "B" (good), and a CDU exposure margin of 5.0 nm or less was evaluated as "C" (poor).

[0180] [Defect Suppression] Following the procedure for forming the resist pattern described above, a resist film was exposed to an optimal exposure dose to form a 25 nm contact hole pattern, and this was used as a wafer for defect inspection. The number of defects on this wafer for defect inspection was measured using a defect inspection device (KLA-Tencor's "KLA2810"). The measured defects were then classified into those determined to be originating from the resist film and those due to foreign matter of external origin. Defect suppression was judged based on the number of defects after development, with a rating of "A" (very good) for a number of defects determined to be originating from the resist film, "B" (good) for a number of defects between 30 and 100, and "C" (poor) for a number of defects greater than 100.

[0181]

[0182]

[0183] As is clear from the results in Tables 5 and 6, the radiation-sensitive compositions of Examples 1 to 81 all achieved well-balanced improvements in CDU performance, CDU exposure margin, and defect suppression performance compared to the radiation-sensitive compositions of Comparative Examples 1 to 6.

[0184] The radiation-sensitive composition and method for forming a resist pattern according to the present disclosure can form a resist pattern that exhibits good CDU performance, exhibits minimal change in CDU performance due to differences in exposure conditions, and generates few defects. Therefore, these compositions can be suitably used for forming fine resist patterns in the lithography processes of various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. A radiation-sensitive composition comprising a polymer (A) containing a structural unit represented by the following formula (1), and satisfying one or more of the following requirements 1 and 2: Requirement 1: the polymer (A) further contains a structural unit derived from a radiation-sensitive onium salt; Requirement 2: the composition further contains a non-polymeric radiation-sensitive onium salt (B), and at least one selected from the group consisting of the polymer (A) and the radiation-sensitive onium salt (B) contained in the composition has an iodine atom. (In formula (1), R １ and R ２ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a fluoromethyl group. １ is a single bond or a divalent organic group. １ is an acid-dissociable group.) 2. The radiation-sensitive composition according to claim 1, wherein the polymer (A) further contains a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring.

3. The radiation-sensitive composition according to claim 1, wherein the structural unit represented by the formula (1) has an iodine atom.

4. P in the above formula (1) １ The radiation-sensitive composition according to claim 3 , wherein contains an iodine atom.

5. P in the above formula (1) １ The radiation-sensitive composition according to claim 1 , wherein has a ring structure.

6. P in the above formula (1) １ The radiation-sensitive composition according to claim 5 , wherein has an aromatic ring.

7. L in the above formula (1) １ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, or is a substituted or unsubstituted divalent hydrocarbon group in which a methylene group is substituted with a group containing at least one heteroatom selected from the group consisting of an oxygen atom, a sulfur atom, and a nitrogen atom and has 1 to 20 carbon atoms.

8. L in the above formula (1) １ 2. The radiation-sensitive composition according to claim 1, wherein is a methylene group or an ethylene group.

9. The radiation-sensitive composition according to claim 1, which satisfies Requirement 2, wherein the radiation-sensitive onium salt (B) comprises a first onium salt that generates an acid upon exposure, and a second onium salt that generates an acid that is weaker in acidity than the acid generated by the first onium salt upon exposure.

10. The radiation-sensitive composition according to claim 9, wherein at least one selected from the group consisting of the first onium salt and the second onium salt has an iodine atom.

11. The radiation-sensitive composition according to claim 9, wherein the first onium salt and the second onium salt each contain an iodine atom.

12. The radiation-sensitive composition according to claim 1, which satisfies Requirement 1, and wherein the structural unit derived from the radiation-sensitive onium salt in the polymer (A) has an iodine atom.

13. 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 12; exposing the resist film; and developing the exposed resist film.

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

15. A polymer comprising a structural unit represented by the following formula (1) and having an iodine atom: (In formula (1), R １ and R ２ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a fluoromethyl group. １ is a single bond or a divalent organic group. １ is an acid-dissociable group.) 16. P in the above formula (1) １ The polymer according to claim 15 , wherein has an iodine atom.

17. A compound represented by the following formula (2): (In formula (2), R １ and R ２ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a fluoromethyl group. １ is a single bond or a divalent organic group. １Ａ is an acid-dissociable group having an iodine atom.

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