Onium salt, photoacid generator, chemically amplified resist composition, and pattern formation method

Abstract

The present invention relates to an onium salt represented by general formula (A). This provides an onium salt that is highly sensitive in photolithography using high-energy rays and can be used in chemically amplified resist compositions that exhibit excellent lithographic performance such as CDU, MEEF, and LWR. [Formula 1] TIFF0007874242000127.tif2894[In the formula, m1 is an integer from 1 to 4. m2 is 1 or 2. R 1 L is one of the following: a hydrogen atom, a hydrocarbyl group, or an electron-withdrawing group such as a cyano group. A and L B This is a single bond, carbonyl group, ether bond, ester bond, amide bond, sulfonic acid ester bond, sulfonamide bond, carbonate bond, carbamate bond, or hydrocarbylene group. 1 This is a hydrocarbylene group containing an alicyclic structure, and has two bonds on the carbon atoms forming the alicyclic structure. 2 This is a hydrocarbyl group containing an alicyclic structure. + This is an onium cation.

Description

[Technical Field] 【0001】 The present invention relates to an onium salt, a photoacid generator, a chemically amplified resist composition, and a pattern forming method. [Background technology] 【0002】 With the increasing integration and speed of LSIs, the miniaturization of pattern rules is progressing rapidly. In particular, the expansion of the flash memory market and the increase in storage capacity are driving this miniaturization. As for the most advanced miniaturization technology, mass production of 65nm node devices using ArF lithography is underway, and preparations for mass production of next-generation 45nm node devices using ArF immersion lithography are underway. For next-generation 32nm node devices, immersion lithography using ultra-high NA lenses combining a liquid with a higher refractive index than water, a high refractive index lens, and a high refractive index resist film, extreme ultraviolet (EUV) lithography with a wavelength of 13.5nm, and double exposure (double patterning lithography) of ArF lithography are among the candidates and are currently being investigated. 【0003】 The chemically amplified resist composition used in the aforementioned lithography employs a compound that decomposes upon exposure to generate acid (hereinafter referred to as "photoacid generator"). By optimizing the structure within the photoacid generator, acid diffusion can be suppressed, enabling the formation of high-resolution patterns. Generally, shortening the acid diffusion length eliminates image blurring due to acid diffusion, resulting in good mask dimension dependence (mask error factor: MEEF) and dimensional uniformity (CDU). 【0004】 On the other hand, since ArF immersion lithography uses a light source with a wavelength of 193 nm, it is most common to select a photoacid generator that is highly transparent at a wavelength of 193 nm. Therefore, by incorporating alicyclic structures such as adamantane and norbornane into the acid generator, acid diffusion can be effectively suppressed. Furthermore, structures such as adamantanone and norbornane lactone, which incorporate heteroatoms such as oxygen atoms into these structures, can further suppress acid diffusion. Patent Document 1 proposes an acid generator containing a specific alicyclic structure. 【0005】 Conventional photoacid generators increase acidity by having electron-withdrawing groups, such as halogen atoms, near the acid generation site. In particular, because fluorine atoms have the highest electronegativity, onium salts containing perfluoroalkanesulfonic acid anions are commonly used as photoacid generators. However, the generated acid, perfluoroalkanesulfonic acid, lacks degradable groups such as ester structures and hardly decomposes in nature, making it a persistent compound that remains in the environment for long periods. Furthermore, because it is water-soluble, it diffuses widely through water systems, resulting in a significant environmental burden and becoming a problem in modern society. 【0006】 The health effects of perfluoroalkyl compounds (PFAS) have been pointed out, and there are movements to restrict the manufacture and sale of PFAS compounds under the European REACH initiative. Many compounds containing PFAS are currently used in semiconductor lithography. For example, materials containing PFAS are used in surfactants and acid generators. The photoacid generators described in Patent Documents 2 and 3 are all based on fluoroalkanesulfonic acid units, and these have been pointed out as having significant health and environmental impacts. Furthermore, in recent years, there has been a growing demand not only for non-PFAS materials represented by these, but also for non-fluorine materials that do not contain fluorine atoms. 【0007】 Patent documents 4, 5, and 6 describe alkanesulfonic acid-type photoacid generators having electron-withdrawing groups as substituents, as an alternative to PFAS. Patent document 6 also describes an attempt to increase acid strength by using a carboxylic acid as an electron-withdrawing group. While these can be applied as non-fluorine materials, further improvements are expected as they are thought to have significant acid diffusion and are not suitable for actual use as resist materials. 【0008】 Patent documents 7 to 11 describe various onium salts and compositions containing onium salts that can be used as photoacid generators. However, there has been a need for the development of a new photoacid generator that, when used in acid-catalyzed chemically amplified resist compositions, can exhibit excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby realizing a chemically amplified resist composition with excellent lithography performance. [Prior art documents] [Patent Documents] 【0009】 [Patent Document 1] Japanese Patent Publication No. 2015-117200 [Patent Document 2] Japanese Patent Publication No. 2018-5224 [Patent Document 3] Japanese Patent Publication No. 2018-197853 [Patent Document 4] International Publication No. 2024 / 143131 [Patent Document 5] International Publication No. 2024 / 241766 [Patent Document 6] Japanese Patent Publication No. 2025-079775 [Patent Document 7] International Publication No. 2024 / 185543 [Patent Document 8] International Publication No. 2018 / 168252 [Patent Document 9] Japanese Patent Publication No. 2018-049177 [Patent Document 10] Japanese Patent Publication No. 2015-4967 [Patent Document 11] International Publication No. 2024 / 225059 [Overview of the project] [Problems that the invention aims to solve] 【0010】 In acid-catalyzed chemically amplified resist compositions, there is a need for the development of resist compositions that offer even higher sensitivity, improve lithography performance such as LWR, CDU, exposure margin (EL), depth of field (DOF), and mask dimension dependence (MEEF), and exhibit excellent etching resistance after pattern formation. 【0011】 The present invention has been made in view of the above circumstances, and aims to provide an onium salt used in a chemically amplified resist composition that is highly sensitive and has excellent lithography performance such as CDU, MEEF, and LWR in photolithography using high-energy rays, a photoacid generator consisting of the onium salt, a chemically amplified resist composition containing the photoacid generator, and a method for forming a pattern using the chemically amplified resist composition. [Means for solving the problem] 【0012】 In order to solve the above problems, the present invention provides: The present invention provides an onium salt that is represented by the following general formula (A). [ka] [In the formula, m1 is an integer between 1 and 4. m2 is either 1 or 2.] R 1is, independently of each other, any one of a hydrogen atom, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, and an electron-withdrawing group, and the electron-withdrawing group is a halogen atom excluding a fluorine atom, a cyano group, a nitro group, and a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group, a hydrocarbylcarbonyl group, a hydrocarbyloxycarbonyl group, a hydrocarbylcarbonyloxy group, a hydrocarbylsulfonyl group, and a hydrocarbyloxysulfonyl group, and the aforementioned R 1 at least one of which is the aforementioned electron-withdrawing group. L A and L B are, independently of each other, a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, an oxalyl (-C(=O)C(=O)-) bond, or a hydrocarbylene group having 1 to 10 carbon atoms which may contain a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond or a carbamate bond. W 1 is a hydrocarbylene group having 3 to 40 carbon atoms which does not contain an aromatic ring and contains an alicyclic structure, and may contain a heteroatom. However, the aforementioned W 1 has two bonds with the adjacent aforementioned L A or the aforementioned L B on the carbon atom forming the alicyclic structure. W 2 is a hydrocarbyl group having 3 to 40 carbon atoms which does not contain an aromatic ring and contains an alicyclic structure, and may contain a heteroatom. Z + is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2). 【Chemical formula】 (In the formula, R ct1 ~R ct5 are, independently of each other, a halogen atom, or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. Also, Rct1 and R ct2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. 【0013】 Such an onium salt is used in chemically amplified resist compositions that exhibit excellent solvent solubility, high sensitivity, and high contrast, as well as superior lithography performance such as CDU, MEEF, LWR, EL, and DOF, particularly in photolithography using high-energy beams such as KrF excimer laser light, ArF excimer laser light, electron beams (EB), and EUV. It also has strong resistance to pattern deformation during fine pattern formation. 【0014】 Furthermore, the onium salt of the present invention is the same as the W 1 and W 2 At least one of these may include a lactone ring structure or a sultone ring structure. 【0015】 By introducing such polar groups, acid diffusion in the resist can be further suppressed. 【0016】 Furthermore, the onium salt of the present invention is R 1 Preferably, at least one of them is a cyano group or a nitro group. 【0017】 Such materials, in particular, have high acid strength and high sensitivity. 【0018】 Furthermore, the onium salt of the present invention is preferably represented by the following general formula (A-1). [ka] (In the formula, m12 is an integer between 0 and 3. R 1 , L B , W 1 , W 2 and Z + The same as above. R 3 R 1 Same as above. L A2These are ether bonds, ester bonds, amide bonds, sulfonic acid ester bonds, sulfonamide bonds, carbonate bonds, or carbamate bonds. 【0019】 With such a design, the effects of the present invention can be more fully realized. 【0020】 Furthermore, the present invention provides a photoacid generator comprising the above-mentioned onium salt. 【0021】 The photoacid generator of the present invention is particularly useful in photolithography using high-energy beams such as KrF excimer laser light, ArF excimer laser light, electron beams (EB), and EUV, as it exhibits excellent solvent solubility, high sensitivity, high contrast, and superior lithography performance such as CDU, MEEF, LWR, EL, and DOF, and is also resistant to pattern deformation during fine pattern formation in chemically amplified resist compositions. 【0022】 Furthermore, the present invention provides a chemically amplified resist composition comprising (A) the above-mentioned photoacid generator. 【0023】 Such a chemically amplified resist composition exhibits excellent solvent solubility, high sensitivity, and high contrast, as well as superior lithography performance in areas such as CDU, MEEF, LWR, EL, and DOF, particularly in photolithography using high-energy beams like KrF excimer laser light, ArF excimer laser light, electron beams (EB), and EUV. It also provides strong resistance to pattern deformation during fine pattern formation. 【0024】 Furthermore, it is preferable that the chemically amplified resist composition further includes a (B)-based polymer containing repeating units having acid-unstable groups. 【0025】 In this case, it is even more preferable that the repeating unit having the acid-unstable group is represented by the following general formula (B1). [ka] (In the formula, R A R is a hydrogen atom or a methyl group. AL It is an acid-unstable group. 【0026】 Such a chemically amplified resist composition can be a positive-type resist composition. Alternatively, the chemically amplified resist composition of the present invention can be a negative-type resist composition in organic solvent development even without the presence of a crosslinking agent. 【0027】 Furthermore, it is preferable that the (B) base polymer contains at least one selected from the repeating units represented by the following general formula (B2), the repeating units represented by the following general formula (B3), and the repeating units represented by the following general formula (B4). [ka] (In the formula, R A R is a hydrogen atom or a methyl group. 11 and R 12 Each of these is independently either a hydrogen atom or a hydroxyl group. 13 R is a substituent having a lactone structure or a substituent having a sultone structure. 14 (This is a hydrogen atom, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or a monovalent fluoroalcohol-containing substituent having 1 to 15 carbon atoms.) 【0028】 (B) The base polymer may contain various repeating units as needed. 【0029】 Furthermore, it is preferable that the chemically amplified resist composition further contains (C) an organic solvent. 【0030】 Such a material is preferable because it improves the applicability. 【0031】 Furthermore, the chemically amplified resist composition may further include a (D) fluorine atom-containing polymer comprising at least one selected from the following general formulas (D1), (D2), (D3), and (D4). [ka] (In the formula, R B This is either a hydrogen atom or a methyl group. R 21 and R 22 Each of these is independently either a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. R 23 This is a single-bonded, linear, or branched hydrocarbylene group having 1 to 5 carbon atoms. R 24 , R 25 and R 26 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group, a C1-C15 fluorinated hydrocarbyl group, a C2-C15 acyl group, or an acid-unstable group. 24 , R 25 and R 26 When the group is a hydrocarbyl group or a fluorinated hydrocarbyl group, some of these -CH2- groups may be substituted with ether bonds or carbonyl groups. R 27 This is a (k+1) valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1) valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. k is an integer between 1 and 3. X 21 These are, independently, a single bond, an ester bond, an ether bond, an amide bond, or a phenylene bond. X 22 Each of these is independently a single bond or a hydroxylylene group having 1 to 20 carbon atoms when p is 1, and a trivalent hydrocarbon group having 1 to 20 carbon atoms when p is 2, and the hydroxylylene group and the trivalent hydrocarbon group may contain at least one selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a halogen atom. p is an integer, either 1 or 2. X 23 These are, independently, a single bond, an ester bond, an ether bond, an amide bond, a sulfonic acid ester bond, a urethane bond, a thiourethane bond, and a urea bond. Ar is a group derived from benzene or naphthalene. R 28 Each of these is independently a hydrogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 6 carbon atoms, a hydroxyl group, a carboxyl group, a halogen atom, a cyano group, or a nitro group. m is an integer between 1 and 5. 【0032】 Furthermore, the chemically amplified resist composition may further contain (E) a quencher. 【0033】 Furthermore, the chemically amplified resist composition may further contain (G) a surfactant. 【0034】 The chemically amplified resist composition of the present invention may optionally contain such components in addition to the base polymer described above. 【0035】 Furthermore, in this invention, The present invention provides a pattern formation method comprising the steps of: forming a resist film on a substrate using the above-mentioned chemically amplified resist composition; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer. 【0036】 By using the chemically amplified resist composition of the present invention, particularly in photolithography using high-energy beams such as KrF excimer laser light, ArF excimer laser light, electron beams (EB), and EUV, the resist composition exhibits excellent solvent solubility, high sensitivity, high contrast, and superior lithography performance in areas such as CDU, MEEF, LWR, EL, and DOF, as well as robust resistance to pattern deformation during fine pattern formation. 【0037】 Furthermore, it is preferable to use KrF excimer laser light, ArF excimer laser light, electron beams, or extreme ultraviolet light with a wavelength of 3 to 15 nm as the high-energy beam. 【0038】 In the pattern formation method of the present invention, such high-energy rays can be used particularly suitably. [Effects of the Invention] 【0039】 The photoacid generator comprising the onium salt of the present invention is highly sensitive because the vicinity of the sulfonate anion is substituted with an electron-withdrawing group, and it is an environmentally friendly material because it does not contain fluorine atoms. Furthermore, the photoacid generator comprising the onium salt of the present invention has a structure in which two or more alicyclic groups are included in the main backbone of the molecule, making it rigid and large in molecular size, and therefore low in diffusivity, which makes it possible to improve lithography performance such as CDU, MEEF, LWR, EL, and DOF. [Modes for carrying out the invention] 【0040】 As described above, in photolithography using high-energy rays, there has been a need for the development of onium salts used in chemically amplified resist compositions that are highly sensitive and have excellent lithographic performance such as CDU, MEEF, and LWR, photoacid generators made from said onium salts, chemically amplified resist compositions containing said photoacid generators, and pattern formation methods using said chemically amplified resist compositions. 【0041】 As a result of diligent research to achieve the above objective, the present inventors have discovered that by using an onium salt having a structure in which the vicinity of the sulfonate anion is substituted with a predetermined electron-withdrawing group and the main backbone of the molecule contains two or more alicyclic groups as a photoacid generator, a chemically amplified resist composition that is highly sensitive in photolithography using high-energy rays and has excellent lithographic performance such as CDU, MEEF, and LWR can be obtained, thus completing the present invention. 【0042】 In other words, the present invention is an onium salt represented by the following general formula (A). [ka] [In the formula, m1 is an integer between 1 and 4. m2 is either 1 or 2.] R 1 Each of these is independently a hydrogen atom, a C1-C20 hydrocarbyl group which may contain a heteroatom, and an electron-withdrawing group, and the electron-withdrawing group is a halogen atom other than a fluorine atom, a cyano group, a nitro group, and a C1-C20 hydrocarbyloxy group, hydrocarbylthio group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, hydrocarbylsulfonyl group, and hydrocarbyloxysulfonyl group which may contain a heteroatom, and the R 1 At least one of them is the aforementioned electron-withdrawing group. L A and L B Each of these is independently a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, an oxalyl (-C(=O)C(=O)-) bond, or a 1-10 carbon dioxide hydrocarbylene group which may contain a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, or a carbamate bond. W 1 This is a hydrocarbylene group having 3 to 40 carbon atoms that does not contain an aromatic ring and contains an alicyclic structure, and may contain a heteroatom. However, the aforementioned W 1 is adjacent to L A or L B It has two bonding bonds on the carbon atoms forming the alicyclic structure. 2 This refers to a hydrocarbyl group having 3 to 40 carbon atoms that does not contain an aromatic ring but contains an alicyclic structure, and may also contain a heteroatom. Z + This is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2). [ka] (In the formula, R ct1 ~R ct5 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ct1 and R ct2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. 【0043】 The present invention will be described in detail below, but the present invention is not limited to these descriptions. 【0044】 [Onium salt] The onium salt of the present invention is represented by the following general formula (A). [ka] [In the formula, m1 is an integer between 1 and 4. m2 is either 1 or 2.] R 1 Each of these is independently a hydrogen atom, a C1-C20 hydrocarbyl group which may contain a heteroatom, and an electron-withdrawing group, and the electron-withdrawing group is a halogen atom other than a fluorine atom, a cyano group, a nitro group, and a C1-C20 hydrocarbyloxy group, hydrocarbylthio group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, hydrocarbylsulfonyl group, and hydrocarbyloxysulfonyl group which may contain a heteroatom, and the R 1 At least one of them is the aforementioned electron-withdrawing group. L A and L B Each of these is independently a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, an oxalyl (-C(=O)C(=O)-) bond, or a 1-10 carbon dioxide hydrocarbylene group which may contain a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, or a carbamate bond. W1 This is a hydrocarbylene group having 3 to 40 carbon atoms that does not contain an aromatic ring and contains an alicyclic structure, and may contain a heteroatom. However, the aforementioned W 1 is adjacent to L A or L B It has two bonding bonds on the carbon atoms forming the alicyclic structure. 2 This refers to a hydrocarbyl group having 3 to 40 carbon atoms that does not contain an aromatic ring but contains an alicyclic structure, and may also contain a heteroatom. Z + This is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2). [ka] (In the formula, R ct1 ~R ct5 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ct1 and R ct2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. 【0045】 <Anion part> As represented by general formula (A), the onium salt of the present invention has a sulfonate ion (SO3) in the anionic portion. - The molecule has a sulfonic acid ion, the vicinity of which is substituted with at least one electron-withdrawing group, and the main backbone of the molecule has two or more alicyclic structures. The anionic portion will be described in detail below. 【0046】 In general formula (A), m1 is an integer from 1 to 4. m1 is preferably 1 to 2, and more preferably 1. In this case, the mobility of the sulfonate anion is reduced, and acid diffusion can be suppressed. 【0047】 In general formula (A), R 1Each of these is independently a hydrogen atom, a C1-C20 hydrocarbyl group which may contain a heteroatom, and an electron-withdrawing group, and the electron-withdrawing group is a halogen atom other than a fluorine atom, a cyano group, a nitro group, and a C1-C20 hydrocarbyloxy group, hydrocarbylthio group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, hydrocarbylsulfonyl group, and hydrocarbyloxysulfonyl group which may contain a heteroatom, and the R 1 At least one of these is the aforementioned electron-withdrawing group. By substituting the vicinity of the sulfonate anion with an electron-withdrawing group other than a fluorine atom, it is possible to reduce the fluorine atom content of the photoacid generator and, consequently, the resist composition, while maintaining the acid strength of the photoacid generator, thereby reducing the environmental impact. 【0048】 As an electron-withdrawing group, the m-substituent constant σ in Hammett's rule described in Chem. Rev. 1991, 91, 165-169 is used. m A value greater than 0 is preferred, a value greater than 0.35 is more preferred, and it is even more preferred to be a nitro group, a cyano group, a hydrocarbylcarbonyl group (particularly an acetyl group), a hydrocarbyloxycarbonyl group, and a hydrocarbylcarbonyloxy group, with the cyano group being the most preferred. By bonding the electron-withdrawing group near the sulfonic acid anion, the acid strength of the sulfonic acid can be increased by an inductive effect. On the other hand, it is preferable that the electron-withdrawing group does not contain groups that act as hydrogen bond donors, such as amino groups, mercapto groups, carboxylic acid groups, sulfonic acid groups, and aldehyde groups, and it is even more preferable that these hydrogen bond donor groups do not substitute for the α-position of the sulfonic acid. When these are present near the sulfonic acid, the nucleophilicity of the hydrogen bond donor from which a hydrogen atom is abstracted by the sulfonic acid anion through intramolecular hydrogen bonding increases, and the sensitivity decreases. Hammett substituent constant σ for each group in this specification mThe values ​​used are those listed in Chem. Rev. 1991, 91, 165-169. For values ​​not listed, the difference between the pKa of benzoic acid and the pKa of a benzoic acid derivative with a substituent at the meta position is calculated using the software ACD / ChemSketch (ACD / Labs 8.00 Release Product Version: 8.08). m Find the value. 【0049】 In particular, it is preferable that the α- or β-position of the sulfonic acid anion is substituted with an electron-withdrawing group, and more preferably that the α-position is substituted. In this case, the acid strength is highest and the sensitivity is highest. In particular, it is preferable that the α-position of the sulfonic acid is substituted with a cyano group or a nitro group. 【0050】 More specifically, possible substitution locations for electron-withdrawing groups include, for example, (1) having only one electron-withdrawing group at the α-position of the sulfonate anion and no electron-withdrawing group at the β-position, (2) having two electron-withdrawing groups at the α-position of the sulfonate anion and no electron-withdrawing group at the β-position, (3) having only one electron-withdrawing group at the β-position of the sulfonate anion and no electron-withdrawing group at the α-position, and (4) having only one electron-withdrawing group at the α-position and only one electron-withdrawing group at the β-position. Note that if there are two or more electron-withdrawing groups, they may be the same or different. 【0051】 The hydrocarbyl group, as well as the hydrocarbyl portion of the hydrocarbyloxy group, hydrocarbylthio group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, hydrocarbylsulfonyl group, and hydrocarbyloxysulfonyl group, may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C20 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl groups; cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, and 4-methyl groups. Examples include cyclic saturated hydrocarbyl groups with 3 to 20 carbon atoms, such as cyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups with 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated hydrocarbyl groups with 3 to 20 carbon atoms, such as cyclohexenyl; aryl groups with 2 to 20 carbon atoms, such as phenyl and naphthyl; aralkyl groups with 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen, sulfur, or nitrogen atoms, and as a result, the material may contain hydroxyl groups, cyano groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc. 【0052】 Examples of halogen atoms other than fluorine atoms include chlorine atoms, bromine atoms, and iodine atoms. 【0053】 L A and L B each independently represents a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, an oxalyl (-C(=O)C(=O)-) bond, or a C1-C10 hydrocarbylene group which may contain a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond or a carbamate bond. L A An ester bond (*-O-C(=O)-**, or *-C(=O)-O-**) is preferred as L 2 and an ester bond (*-C(=O)-O-**) is more preferred (* and ** each represent a bond to the W 3- side and the SO B An ester bond (*-O-C(=O)-**, or *-C(=O)-O-**) is preferred as L 1 and an ester bond represented by *-O-C(=O)-** is more preferred (* and ** each represent a bond to the W 3- side and the SO 【0054】 In the general formula (A), m2 is 1 or 2, and preferably 1. 【0055】 W 1 is a C3-C40 hydrocarbylene group which does not contain an aromatic ring and contains an alicyclic structure, and may contain a hetero atom. However, the above W 1 has two bonds to the adjacent L A or the L B on the carbon atoms forming the alicyclic structure. W 2 is a C3-C40 hydrocarbyl group which does not contain an aromatic ring and contains an alicyclic structure, and may contain a hetero atom. 【0056】 In the onium salt of the present invention, W 1 contains an alicyclic structure and W 2Since it also contains an alicyclic structure, it has two or more alicyclic structures in the molecule. The alicyclic structures contained in this molecule increase the molecular size. Furthermore, W 1 has two bonds with adjacent L A or L B on the carbon atoms forming the alicyclic structure, so that the alicyclic structure of W 1 is located at the center of the onium salt molecule so to speak. As a result, the alicyclic structure of W 2 , the alicyclic structure of W 1 , and the sulfonic acid anion part are arranged substantially linearly (in the main skeleton part) in the molecule, and the onium salt molecule becomes more rigid. As described above, the onium salt of the present invention has reduced acid diffusion in the resist, and lithography characteristics such as CDU, LWR, and MEEF are improved. Also, W 1 and W 2 both do not contain an aromatic ring such as a benzene ring having a 193 nm absorption, so the sensitivity during ArF exposure is improved, and it can be suitably used as a photoacid generator for ArF exposure. 【0057】 W 1 is preferably a hydrocarbylene group having 6 to 20 carbon atoms, more preferably a hydrocarbylene group having 6 to 10 carbon atoms. Also, the alicyclic structure of W 1 is not particularly limited, but a polycyclic structure such as adamantane is more preferable than a monocyclic structure such as cyclohexane from the viewpoint of increasing rigidity. Also, W 1 may contain a heteroatom, and examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom. The alicyclic structure of W 1 may be a lactone ring structure or a sultone ring structure. By introducing such a polar group, acid diffusion in the resist can be further suppressed. 【0058】 W 2 is preferably a hydrocarbylene group having 6 to 20 carbon atoms, more preferably a hydrocarbylene group having 6 to 10 carbon atoms. Also W 2The alicyclic structure is not particularly limited, but a polycyclic structure like adamantane is preferable to a monocyclic structure like cyclohexane in terms of increased rigidity. 2 It may contain heteroatoms, and examples of such heteroatoms include oxygen atoms, nitrogen atoms, sulfur atoms, etc. 2 The alicyclic structure may be a lactone ring structure or a sultone ring structure. Introducing such polar groups can further suppress acid diffusion in the resist. 【0059】 W 1 Specific examples of the hydrocarbylene group are listed below, but are not limited to these. In the following formulas, * represents L A or L B This is the bonding bond. In the following explanation, depending on the structure represented by the chemical formula, there may be a chiral carbon, and enantiomers or diastereomers may exist. In such cases, one formula will represent all of these isomers. These isomers may be used individually or as a mixture of two or more. 【0060】 [ka] 【0061】 [ka] 【0062】 W 2 Specific examples of the hydrocarbylene group are listed below, but are not limited to these. In the following formulas, * represents L A This is a combination of the two. 【0063】 [ka] 【0064】 [ka] 【0065】 [ka] 【0066】 [ka] 【0067】 Furthermore, the onium salt of the present invention is preferably represented by the following general formula (A-1). [ka] (In the formula, m12 is an integer between 0 and 3. R 1 , L B , W 1 , W 2 and Z + The same as above. R 3 R 1 Same as above. L A2 These are ether bonds, ester bonds, amide bonds, sulfonic acid ester bonds, sulfonamide bonds, carbonate bonds, or carbamate bonds. 【0068】 Specific examples of anions of onium salts represented by general formula (A) are shown below, but are not limited to these. Furthermore, the bonding positions of the various substituents on the aromatic ring may be interchanged. 【0069】 [ka] 【0070】 [ka] 【0071】 [ka] 【0072】 [ka] 【0073】 [ka] 【0074】 [ka] 【0075】 [ka] 【0076】 [ka] 【0077】 [ka] 【0078】 <Cation portion> In general formula (A), Z + This is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2). [ka] 【0079】 In general formulas (Z-1) and (Z-2), R ct1 ~R ct5 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom. 【0080】 R ct1 ~R ct5Specific examples of halogen atoms represented by include fluorine, chlorine, bromine, and iodine atoms. 【0081】 R ct1 ~R ct5 The hydrocarbyl group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include C1-C30 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl groups; C3-C30 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; C2-C30 alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; C3-C30 cyclic unsaturated hydrocarbyl groups such as cyclohexenyl groups; C6-C30 aryl groups such as phenyl, naphthyl, and thienyl groups; C7-C30 aralkyl groups such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these, but aryl groups are preferred. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen, sulfur, nitrogen, and halogen atoms, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen, sulfur, and nitrogen atoms, and as a result, it may contain a hydroxyl group, fluorine atom, chlorine atom, bromine atom, iodine atom, cyano group, nitro group, carbonyl group, ether bond, ester bond, sulfonic acid ester bond, carbonate bond, lactone ring, sultone ring, carboxylic acid anhydride (-C(=O)-OC(=O)-), or haloalkyl group, etc. 【0082】 Also, R ct1 and R ct2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. In this case, specific examples of the structure of the ring include those represented by the following formula. 【0083】 [ka] (In the formula, the dashed line represents R ct3 (This is a combination of the two.) 【0084】 Specific examples of sulfonium cations represented by the general formula (Z-1) are listed below, but are not limited to these. 【0085】 [ka] 【0086】 [ka] 【0087】 [ka] 【0088】 [ka] 【0089】 [ka] 【0090】 [ka] 【0091】 [ka] 【0092】 [ka] 【0093】 【change】 【0094】 【change】 【0095】 【change】 【0096】 【change】 【0097】 【change】 【0098】 【change】 【0099】 【change】 【0100】 【change】 【0101】 【change】 【0102】 【change】 【0103】 【change】 【0104】 【change】 【0105】 【change】 【0106】 【change】 【0107】 【change】 【0108】 【change】 【0109】 【change】 【0110】 【change】 【0111】 【change】 【0112】 【change】 【0113】 【change】 【0114】 [Chemical] 【0115】 [Chemical] 【0116】 [Chemical] 【0117】 [Chemical] 【0118】 [Chemical] 【0119】 [Chemical] 【0120】 [Chemical] 【0121】 Specific examples of the iodonium cation represented by the general formula (Z-2) include, but are not limited to, those shown below. 【0122】 [Chemical] 【0123】 [Chemical] <000100​​ 【0125】 The onium salt monomer of the present invention can be synthesized, for example, by a method similar to that of the polymerizable anion sulfonium salt described in Japanese Patent No. 5201363, but the method for producing the onium salt monomer of the present invention is not limited thereto. 【0126】 [Photoacid Generator] The photoacid generator of the present invention comprises the onium salt of the present invention. 【0127】 As explained above, the photoacid generator of the present invention, when used in a chemically amplified resist composition catalyzed with an acid, exhibits excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby enabling the realization of a chemically amplified resist composition with excellent lithography performance. 【0128】 [Chemically Amplified Resist Composition] The chemically amplified resist composition of the present invention is characterized by containing (A) the photoacid generator of the present invention. 【0129】 In the chemically amplified resist composition of the present invention, the amount of (A) the photoacid generator of the present invention is not particularly limited, but for example, it can be 1 to 50 parts by mass, preferably 5 to 20 parts by mass, per 100 parts by mass of (B) the base polymer described later. 【0130】 Since such a chemically amplified resist composition of the present invention contains the photoacid generator of the present invention, it can exhibit excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby demonstrating excellent lithography performance. 【0131】 The chemically amplified resist composition of the present invention may further contain other components of the photoacid generator of the present invention. The following describes optional components of the chemically amplified resist composition of the present invention. 【0132】 <(B) Base polymer> The chemically amplified resist composition of the present invention may typically contain a (B)-based polymer. 【0133】 For example, the chemically amplified resist composition of the present invention preferably further comprises (B) a base polymer containing repeating units having an acid-unstable group. 【0134】 Such chemically amplified resist compositions can become positive-type resist compositions. 【0135】 In this case, the repeating unit having an acid-unstable group may be represented, for example, by the following general formula (B1). [ka] (In the formula, R A R is a hydrogen atom or a methyl group. AL It is an acid-unstable group. 【0136】 The repeating unit having an acid-unstable group is not particularly limited, but may be represented by the general formula (B1) above, for example. 【0137】 acid labile group R AL Various types can be selected, but examples include those represented by the following formulas (AL-1) to (AL-3). 【0138】 [ka] (In the equation, dashed lines represent connections.) 【0139】 In equation (AL-1), b is 0, 1, 2, 3, 4, 5, or 6. L1This refers to a tertiary hydrocarbyl group having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms; a trihydrocarbylsilyl group in which each hydrocarbyl group is a saturated hydrocarbyl group having 1 to 6 carbon atoms; a carbonyl group; a saturated hydrocarbyl group having 4 to 20 carbon atoms including an ether bond or an ester bond; or a group represented by formula (AL-3). A tertiary hydrocarbyl group refers to a group obtained by the removal of a hydrogen atom from a tertiary carbon atom of a hydrocarbon. 【0140】 R L1 The tertiary hydrocarbyl group represented by may be saturated or unsaturated, and may be branched or cyclic. Specific examples include tert-butyl group, tert-pentyl group, 1,1-diethylpropyl group, 1-ethylcyclopentyl group, 1-butylcyclopentyl group, 1-ethylcyclohexyl group, 1-butylcyclohexyl group, 1-ethyl-2-cyclopentenyl group, 1-ethyl-2-cyclohexenyl group, and 2-methyl-2-adamantyl group. Specific examples of the trihydrocarbyl silyl group include trimethylsilyl group, triethylsilyl group, and dimethyl-tert-butylsilyl group. The saturated hydrocarbyl group containing the carbonyl group, ether bond, or ester bond may be linear, branched, or cyclic, but a cyclic form is preferred. Specific examples include the 3-oxocyclohexyl group, the 4-methyl-2-oxooxan-4-yl group, the 5-methyl-2-oxooxolan-5-yl group, the 2-tetrahydropyranyl group, and the 2-tetrahydrofuranyl group. 【0141】 Specific examples of acid-unstable groups represented by formula (AL-1) include tert-butoxycarbonyl group, tert-butoxycarbonylmethyl group, tert-pentyloxycarbonyl group, tert-pentyloxycarbonylmethyl group, 1,1-diethylpropyloxycarbonyl group, 1,1-diethylpropyloxycarbonylmethyl group, 1-ethylcyclopentyloxycarbonyl group, 1-ethylcyclopentyloxycarbonylmethyl group, 1-ethyl-2-cyclopentenyloxycarbonyl group, 1-ethyl-2-cyclopentenyloxycarbonylmethyl group, 1-ethoxyethoxycarbonylmethyl group, 2-tetrahydropyranyloxycarbonylmethyl group, and 2-tetrahydrofuranyloxycarbonylmethyl group. 【0142】 Furthermore, other acid-unstable groups represented by formula (AL-1) include those represented by the following formulas (AL-1)-1 to (AL-1)-10. 【0143】 [ka] (In the equation, dashed lines represent connections.) 【0144】 In equations (AL-1)-1 to (AL-1)-10, b is the same as described above. L8 Each of these is independently a saturated hydrocarbyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. L9 R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. L10 This is a saturated hydrocarbyl group having 2 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. 【0145】 In formula (AL-2), R L2 and R L3Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic, and specific examples include a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, cyclopentyl group, cyclohexyl group, 2-ethylhexyl group, and n-octyl group. 【0146】 In formula (AL-2), R L4 This is a hydrocarbyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, which may contain heteroatoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples of the hydrocarbyl group include saturated hydrocarbyl groups having 1 to 18 carbon atoms, some of which may be substituted with hydroxyl groups, alkoxy groups, oxo groups, amino groups, or alkylamino groups. Specific examples of such substituted saturated hydrocarbyl groups include those shown below. 【0147】 [ka] (In the equation, dashed lines represent connections.) 【0148】 R L2 and R L3 , R L2 and R L4 , or R L3 and R L4 These atoms may bond with each other to form a ring with the carbon atoms to which they are bonded, or with carbon atoms and oxygen atoms, in which case the R atoms involved in ring formation L2 and R L3 , R L2 and R L4 , or R L3 and R L4 Each of these is an alkanediyl group having 1 to 18 carbon atoms, preferably 1 to 10. The number of carbon atoms in the ring obtained by bonding these is preferably 3 to 10, more preferably 4 to 10. 【0149】 Specific examples of linear or branched acid-unstable groups represented by formula (AL-2) include, but are not limited to, those shown in formulas (AL-2)-1 to (AL-2)-69 below. In the formulas below, dashed lines represent bonds. 【0150】 [ka] 【0151】 [ka] 【0152】 [ka] 【0153】 [ka] 【0154】 Specific examples of cyclic acid-unstable groups represented by formula (AL-2) include tetrahydrofuran-2-yl group, 2-methyltetrahydrofuran-2-yl group, tetrahydropyran-2-yl group, and 2-methyltetrahydropyran-2-yl group. 【0155】 Furthermore, examples of acid-unstable groups include groups represented by the following formulas (AL-2a) or (AL-2b). The polymer may be intermolecularly or intramolecularly crosslinked by these acid-unstable groups. 【0156】 [ka] (In the equation, dashed lines represent connections.) 【0157】 In formula (AL-2a) or (AL-2b), R L11 and R L12Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 8 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. Also, R L11 and R L12 These may bond with each other to form a ring with the carbon atoms to which they are bonded, in which case R L11 and R L12 These are, independently, alkanediyl groups having 1 to 8 carbon atoms. L13 Each of these is independently a saturated hydrocarbylene group having 1 to 10 carbon atoms. The saturated hydrocarbylene group may be linear, branched, or cyclic. Each of c and d is independently an integer from 0 to 10, preferably 0, 1, 2, 3, 4, or 5, and e is an integer from 1 to 7, preferably 1, 2, or 3. 【0158】 In formula (AL-2a) or (AL-2b), L A This is an (e+1) valent aliphatic saturated hydrocarbon group having 1 to 50 carbon atoms, an (e+1) valent alicyclic saturated hydrocarbon group having 3 to 50 carbon atoms, an (e+1) valent aromatic hydrocarbon group having 6 to 50 carbon atoms, or an (e+1) valent heterocyclic group having 3 to 50 carbon atoms. Furthermore, some of the -CH2- atoms in these groups may be substituted with a group containing a heteroatom, and some of the hydrogen atoms in these groups may be substituted with a hydroxyl group, a carboxyl group, an acyl group, or a fluorine atom. A Preferred examples include saturated hydrocarbon groups such as saturated hydrocarbylene groups, trivalent saturated hydrocarbon groups, and tetravalent saturated hydrocarbon groups having 1 to 20 carbon atoms, and arylene groups having 6 to 30 carbon atoms. The saturated hydrocarbon groups may be linear, branched, or cyclic. B These are -C(=O)-O-, -NH-C(=O)-O-, or -NH-C(=O)-NH-. 【0159】 Specific examples of crosslinked acetal groups represented by formula (AL-2a) or (AL-2b) include the groups represented by the following formulas (AL-2)-70 to (AL-2)-77. 【0160】 [ka] (In the equation, dashed lines represent connections.) 【0161】 In formula (AL-3), R L5 This is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and the hydrocarbyl group may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. L6 and R L7 Each of these is independently a C1-C20 hydrocarbyl group, which may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C20 alkyl groups, C3-C20 cyclic saturated hydrocarbyl groups, C2-C20 alkenyl groups, C3-C20 cyclic unsaturated hydrocarbyl groups, and C6-C10 aryl groups. L5 and R L6 The pair, R L5 and R L7 A combination of, or R L6 and R L7 These pairs may bond with each other to form an alicyclic ring with 3 to 20 carbon atoms, together with the carbon atoms to which they are bonded. 【0162】 Specific examples of the group represented by formula (AL-3) include tert-butyl group, 1,1-diethylpropyl group, 1-ethylnorbonyl group, 1-methylcyclopentyl group, 1-ethylcyclopentyl group, 1-isopropylcyclopentyl group, 1-methylcyclohexyl group, 2-(2-methyl)adamantyl group, 2-(2-ethyl)adamantyl group, and tert-pentyl group. 【0163】 Furthermore, specific examples of the group represented by formula (AL-3) include the groups represented by the following formulas (AL-3)-1 to (AL-3)-22. 【0164】 [ka] (In the equation, dashed lines represent connections.) 【0165】 In equations (AL-3)-1 to (AL-3)-22, R L14 Each of these is independently a hydrogen atom, an aliphatic hydrocarbyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 20 carbon atoms. L15 and R L17 Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms. L16 This is an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. Furthermore, a phenyl group is preferred as the aryl group. L18 This is a fluorine atom, an iodine atom, a nitro group, or a trifluoromethyl group. L19 Each of these is independently a hydrogen atom, a fluorine atom, an iodine atom, a nitro group, a saturated hydrocarbyl group having 1 to 8 carbon atoms, or a hydrocarbyloxy group having 1 to 8 carbon atoms. f is 1, 2, 3, 4, or 5. 【0166】 Furthermore, examples of acid-unstable groups include those represented by the following formulas (AL-3)-23 or (AL-3)-24. The polymer may be intramolecularly or intermolecularly crosslinked by these acid-unstable groups. 【0167】 [ka] (In the equation, dashed lines represent connections.) 【0168】 In equations (AL-3)-23 and (AL-3)-24, R L14 This is the same as above. R L20 is a saturated or unsaturated hydrocarbylene group with 1 to 20 carbon atoms and a (g+1) valence, or an arylene group with 6 to 20 carbon atoms and a (g+1) valence, and may contain heteroatoms such as oxygen, sulfur, and nitrogen atoms. The saturated or unsaturated hydrocarbylene group may be linear, branched, or cyclic. g is 1, 2, or 3. 【0169】 In addition to these acid-unstable groups, aromatic group-containing acid-unstable groups described in Japanese Patent Publication No. 5565293, Japanese Patent Publication No. 5434983, Japanese Patent Publication No. 5407941, Japanese Patent Publication No. 5655756, and Japanese Patent Publication No. 5655755 can also be used. 【0170】 Furthermore, the base polymer may include, for example, at least one selected from the group consisting of repeating units represented by the following general formula (B2), repeating units represented by the following general formula (B3), and repeating units represented by the following general formula (B4). [ka] (In the formula, R A This is either a hydrogen atom or a methyl group. R 11 and R 12 Each of these is independently either a hydrogen atom or a hydroxyl group. R 13 This refers to a substituent having a lactone structure or a substituent having a sultone structure. R 14 (This is a hydrogen atom, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or a monovalent fluoroalcohol-containing substituent having 1 to 15 carbon atoms.) 【0171】 The repeating units constituting the base polymer are not particularly limited, but the base polymer may, for example, contain the above-mentioned repeating units. 【0172】 The following are some, but are not limited, specific examples of repeating units represented by the general formula (B2) above. 【0173】 [ka] 【0174】 The following are some, but are not limited, specific examples of repeating units represented by the general formula (B3) above. 【0175】 [ka] 【0176】 [ka] 【0177】 [ka] 【0178】 [ka] 【0179】 [ka] 【0180】 The following are some, but are not limited, specific examples of repeating units represented by the above general formula (B4). 【0181】 [ka] 【0182】 The polymer may further contain repeating units that do not contain other aromatic groups other than those described above. For example, substituted acrylic acid esters such as methyl methacrylate, methyl crotate, dimethyl maleate, and dimethyl itaconate; unsaturated carboxylic acids such as maleic acid, fumaric acid, and itaconic acid; norbornene, norbornene derivatives, and tetracyclo[4.4.0.1 2,5 .17 7,10 It may also contain repeating units derived from monomers that do not contain aromatic groups, such as cyclic olefins such as dodecene derivatives; unsaturated acid anhydrides such as itaconic anhydride; and monomers that do not contain aromatic groups, such as α-methylene-γ-butyrolactones. 【0183】 The weight-average molecular weight (Mw) of the polymer is preferably 1,000 to 500,000, and more preferably 3,000 to 100,000. Within this range, there is no risk of reduced etching resistance or loss of resolution due to insufficient contrast before and after exposure. In this invention, Mw is a polystyrene-converted value measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as the solvent. 【0184】 If the polymer has a broad molecular weight distribution (Mw / Mn), it may contain both low-molecular-weight and high-molecular-weight polymers, which may result in foreign matter being visible on the pattern or deterioration of the pattern shape after exposure. As the pattern rules become finer, the influence of Mw and Mw / Mn tends to increase. Therefore, to obtain a resist composition suitable for fine pattern dimensions, it is preferable that the Mw / Mn of the polymer be narrowly dispersed, between 1.0 and 2.0, and particularly between 1.0 and 1.5. 【0185】 One method for synthesizing the polymer is to polymerize monomers that provide repeating units represented by formula (B1) and, if necessary, repeating units represented by formulas (B2) to (B4) and other repeating units, by heating them in an organic solvent with a radical initiator. Examples of organic solvents used in the polymerization reaction include toluene, benzene, THF, diethyl ether, dioxane, methyl ethyl ketone, γ-butyrolactone, and propylene glycol monomethyl ether acetate (PGMEA). Examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The amount of these initiators added is preferably 0.01 to 25 mol% of the total amount of monomers to be polymerized. The reaction temperature for the polymerization reaction is preferably 50 to 150°C, more preferably 60 to 100°C. The reaction time is preferably 2 to 24 hours. The acid-unstable group may be used as is after being introduced into the monomer, or it may be protected or partially protected after polymerization. In addition, known chain transfer agents such as dodecyl mercaptan and 2-mercaptoethanol may be used to adjust the molecular weight during polymerization. In this case, the amount of chain transfer agent added is preferably in a molar ratio of 0.01 to 10 relative to the total monomer to be polymerized. 【0186】 In the polymer, the preferred content ratio of each repeating unit can be, for example, within the range shown below, but is not limited thereto. 【0187】 (I) The repeating unit represented by formula (B1) is preferably contained in an amount of 1 to 99 mol%, more preferably 20 to 95 mol%, more preferably 30 to 90 mol%, and as needed, (II) At least one selected from the repeating units represented by formula (B2), formula (B3), and formula (B4) is preferably contained in an amount of 0 to 99 mol%, more preferably 1 to 90 mol%, and even more preferably 10 to 70 mol%, (III) Other repeating units may be included, preferably in an amount of 0 to 99 mol%, more preferably 0 to 70 mol%, and even more preferably 0 to 50 mol%. 【0188】 Furthermore, the base polymer of component (B) may be used alone, or two or more types with different composition ratios, Mw, and / or Mw / Mn may be used in combination. 【0189】 <(C) Organic Solvents> The chemically amplified resist composition may further contain, for example, (C) an organic solvent. The organic solvent is not particularly limited as long as it is capable of dissolving the photoacid generator and each optional component of the present invention. Specific examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, as described in paragraphs

[0144] to

[0145] of Japanese Patent Application Publication No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol Examples include ethers such as monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; and lactones such as γ-butyrolactone. 【0190】 In the chemically amplified resist composition of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by mass, and more preferably 200 to 8,000 parts by mass, per 100 parts by mass of the base polymer. The organic solvent may be used alone or as a mixture of two or more types. 【0191】 <(D) Fluorine atom-containing polymer> Furthermore, the chemically amplified resist composition of the present invention may further include a (D) fluorine atom-containing polymer comprising at least one selected from the group consisting of repeating units represented by the following general formula (D1), repeating units represented by the following general formula (D2), repeating units represented by the following general formula (D3), and repeating units represented by the following general formula (D4). [ka] (In the formula, R B This is either a hydrogen atom or a methyl group. R 21 and R 22 Each of these is independently either a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. R 23 This is a single-bonded, linear, or branched hydrocarbylene group having 1 to 5 carbon atoms. R 24 , R 25 and R 26 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group, a C1-C15 fluorinated hydrocarbyl group, a C2-C15 acyl group, or an acid-unstable group. 24 , R 25 and R 26 When the group is a hydrocarbyl group or a fluorinated hydrocarbyl group, some of these -CH2- groups may be substituted with ether bonds or carbonyl groups. R 27 This is a (k+1) valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1) valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. k is an integer between 1 and 3. X 21 These are, independently, a single bond, an ester bond, an ether bond, an amide bond, or a phenylene bond. X 22Each of these is independently a single bond or a hydroxylylene group having 1 to 20 carbon atoms when p is 1, and a trivalent hydrocarbon group having 1 to 20 carbon atoms when p is 2, and the hydroxylylene group and the trivalent hydrocarbon group may contain at least one selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a halogen atom. p is an integer, either 1 or 2. X 23 These are, independently, a single bond, an ester bond, an ether bond, an amide bond, a sulfonic acid ester bond, a urethane bond, a thiourethane bond, and a urea bond. Ar is a group derived from benzene or naphthalene. R 28 Each of these is independently a hydrogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 6 carbon atoms, a hydroxyl group, a carboxyl group, a halogen atom, a cyano group, or a nitro group. m is an integer between 1 and 5. 【0192】 The repeating units represented by formula (D1) include, but are not limited to, the following. Note that in the following formula, R B This is the same as described above. 【0193】 [ka] 【0194】 The repeating units represented by formula (D2) include, but are not limited to, the following. Note that in the following formula, R B This is the same as described above. [ka] 【0195】 The repeating units represented by formula (D3) include, but are not limited to, the following. Note that in the following formula, R B This is the same as described above. [ka] 【0196】 The repeating units represented by formula (D4) include, but are not limited to, the following. Note that in the following formula, R B This is the same as described above. 【0197】 [ka] 【0198】 The fluorine atom-containing polymer may further contain other repeating units other than those represented by any of the formulas (D1) to (D4). Specific examples of other repeating units include repeating units obtained from methacrylic acid or α-trifluoromethylacrylic acid derivatives. In the polymer-type surfactant, the content of the repeating units represented by formulas (D1) to (D4) is preferably 20 mol% or more, more preferably 60 mol% or more, and even more preferably 100 mol% of the total repeating units. 【0199】 The Mw of the fluorine atom-containing polymer of component (D) is preferably 1000 to 100000, and more preferably 3000 to 15000. The Mw / Mn ratio is preferably 1.0 to 2.0, and more preferably 1.0 to 1.6. 【0200】 A method for synthesizing the fluorine atom-containing polymer of component (D) is to polymerize a monomer that gives at least one selected from repeating units represented by formula (D1), formula (D2), formula (D3), and formula (D4), and a monomer that gives other repeating units as needed, by heating it in an organic solvent with a radical initiator. Examples of organic solvents used in the polymerization reaction include toluene, benzene, THF, diethyl ether, dioxane, methyl ethyl ketone, propylene glycol monomethyl ether, and PGMEA. Examples of polymerization initiators include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The reaction temperature for the polymerization reaction is preferably 50 to 100°C. The amount of these initiators added is preferably 0.01 to 25 mol% of the total amount of monomers to be polymerized. The reaction time is preferably 4 to 24 hours. The acid-unstable group may be used as is after being introduced into the monomer, or it may be protected or partially protected after polymerization. In addition, known chain transfer agents such as dodecyl mercaptan and 2-mercaptoethanol may be used to adjust the molecular weight during polymerization. In this case, the amount of chain transfer agent added is preferably in a molar ratio of 0.01 to 10 relative to the total monomer to be polymerized. 【0201】 When the chemically amplified resist composition of the present invention contains a fluorine atom-containing polymer of component (D), its content is preferably 0.1 to 50 parts by mass, and more preferably 0.5 to 10 parts by mass, relative to 80 parts by mass of the base polymer of component (B). If the content of the fluorine atom-containing polymer (D) is within the above range, the contact angle between the resist film surface and water is sufficiently improved, and defects due to residual water immersion and the elution of acid generators and quenchers can be suppressed. Furthermore, it becomes possible to adjust the solubility of the resist film surface, and a good CDU can be achieved. The fluorine atom-containing polymer (D) may be used alone or in combination of two or more types. 【0202】 <(E) Quencher> The chemically amplified resist composition of the present invention may optionally contain a quencher. In the present invention, a quencher means a compound that can prevent the diffusion of acid generated from the photoacid generator into unexposed areas by trapping the acid. 【0203】 Specific examples of the quencher include amine compounds, sulfonates, or carboxylates. As the amine compound, primary, secondary, or tertiary amine compounds described in paragraphs

[0146] to

[0164] of Japanese Patent Publication No. 2008-111103 are preferred, particularly amine compounds having any of the following: a hydroxyl group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonic acid ester bond. Compounds in which a primary or secondary amine is protected as a carbamate group, such as the compound described in Japanese Patent Publication No. 3790649, are also preferred. Such protected amine compounds are effective when there are components in the resist composition that are unstable to a base. 【0204】 Specific examples of the sulfonate include the compound represented by the following formula (1). Furthermore, specific examples of the carboxylate include the compound represented by the following formula (2). 【0205】 [ka] 【0206】 In formula (1), R 101 This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a hydrogen atom or a heteroatom, but SO3 - Excluding those in which the hydrogen atom bonded to the α-carbon atom of the group is substituted with a fluorine atom or a fluoroalkyl group. 【0207】 R 101The C1-C40 hydrocarbyl group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include C1-C40 alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.0 2,6 ] Cyclic saturated hydrocarbyl groups with 3 to 40 carbon atoms, such as decanyl group, adamantyl group, and adamantylmethyl group; alkenyl groups with 2 to 40 carbon atoms, such as vinyl group, 1-propenyl group, 2-propenyl group, butenyl group, and hexenyl group; unsaturated aliphatic cyclic hydrocarbyl groups with 3 to 40 carbon atoms, such as cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl group (e.g., 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butyl group) Examples include aryl groups having 6 to 40 carbon atoms, such as phenyl groups and 4-n-butylphenyl groups, dialkylphenyl groups (e.g., 2,4-dimethylphenyl groups and 2,4,6-triisopropylphenyl groups), alkylnaphthyl groups (e.g., methylnaphthyl groups and ethylnaphthyl groups), and dialkylnaphthyl groups (e.g., dimethylnaphthyl groups and diethylnaphthyl groups); and aralkyl groups having 7 to 40 carbon atoms, such as benzyl groups, 1-phenylethyl groups, and 2-phenylethyl groups. 【0208】 Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, and as a result, it may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), or a haloalkyl group, etc. Examples of hydrocarbyl groups containing heteroatoms include heteroaryl groups such as thienyl groups; alkoxyphenyl groups such as 4-hydroxyphenyl, 4-methoxyphenyl, 3-methoxyphenyl, 2-methoxyphenyl, 4-ethoxyphenyl, 4-tert-butoxyphenyl, and 3-tert-butoxyphenyl groups; alkoxynaphthyl groups such as methoxynaphthyl, ethoxynaphthyl, n-propoxynaphthyl, and n-butoxynaphthyl groups; dialkoxynaphthyl groups such as dimethoxynaphthyl and diethoxynaphthyl groups; and aryloxoalkyl groups such as 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl, 2-(1-naphthyl)-2-oxoethyl, and 2-(2-naphthyl)-2-oxoethyl groups. 【0209】 In formula (2), R 102 R is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain heteroatoms. 102 The hydrocarbyl group represented by R is 101 Examples of hydrocarbyl groups represented by the same formula as those exemplified above include the trifluoromethyl group, trifluoroethyl group, 2,2,2-trifluoro-1-methyl-1-hydroxyethyl group, and 2,2,2-trifluoro-1-(trifluoromethyl)-1-hydroxyethyl group, as well as fluorine-containing aryl groups such as pentafluorophenyl group and 4-trifluoromethylphenyl group. 【0210】 Specific examples of sulfonate anions represented by formula (1) are listed below, but are not limited to these. 【0211】 [ka] 【0212】 [ka] 【0213】 Specific examples of anions of carboxylate salts represented by formula (2) are listed below, but are not limited to these. In the following formulas, Me represents a methyl group. 【0214】 [ka] 【0215】 [ka] 【0216】 [ka] 【0217】 [ka] 【0218】 [ka] 【0219】 In equations (1) and (2), MQ +This is an onium cation. Examples of the onium cation include sulfonium cations, iodonium cations, and ammonium cations. The sulfonium cation is preferably represented by formula (Z-1), and specific examples include those similar to those exemplified as specific examples of sulfonium cations represented by formula (Z-1). The iodonium cation is preferably represented by formula (Z-2), and specific examples include those similar to those exemplified as specific examples of iodonium cations represented by formula (Z-2). 【0220】 Another example of the aforementioned quencher is the polymer-type quencher described in Japanese Patent Publication No. 2008-239918. This enhances the rectangularity of the resist pattern by orientation on the resist surface. The polymer-type quencher also has the effect of preventing film erosion of the pattern and rounding of the pattern top when a protective film for immersion lithography is applied. 【0221】 Furthermore, as a quencher, an onium salt having a sulfonium cation and a phenoxide anion moiety in the same molecule as described in Japanese Patent Publication No. 6848776, an onium salt having a sulfonium cation and a carboxylate anion moiety in the same molecule as described in Japanese Patent Publication No. 6583136 and Japanese Patent Application Publication No. 2020-200311, or an onium salt having an iodonium cation and a carboxylate anion moiety in the same molecule as described in Japanese Patent Publication No. 6274755 can also be used. 【0222】 When the chemically amplified resist composition of the present invention contains a quencher, its content is preferably 0.001 to 12 parts by mass, and more preferably 0.01 to 8 parts by mass, per 80 parts by mass of the base polymer. The inclusion of a quencher facilitates the adjustment of the sensitivity of the resist film, suppresses acid diffusion in the resist film, improves resolution, suppresses sensitivity changes after exposure, reduces substrate and environmental dependence, and improves exposure margin and pattern profile. Furthermore, the addition of the quencher can also improve substrate adhesion. One type of quencher may be used alone, or two or more types may be used in combination. 【0223】 <(G) Surfactants> The chemically amplified resist composition of the present invention may further contain (G) a surfactant. 【0224】 Specific examples of the surfactants mentioned above include those described in paragraphs

[0165] to

[0166] of Japanese Patent Publication No. 2008-111103. By adding surfactants, the coatability of the resist composition can be further improved or controlled. When the resist composition of the present invention contains the surfactant, its content is preferably 0.0001 to 10 parts by mass per 100 parts by mass of the base polymer. The surfactant may be used alone or in combination of two or more types. 【0225】 <Other ingredients> In addition to the components described above, the chemically amplified resist composition of the present invention may also contain an acid generator (other acid generators), a dissolution inhibitor, a crosslinking agent, a water-repellency enhancer, or acetylene alcohols, etc. 【0226】 Examples of the acid generator (other acid generators) include compounds that generate acid in response to active light or radiation (photoacid generators). Any compound that generates acid upon irradiation with high-energy rays can be used as a component of the photoacid generator, but acid generators that generate sulfonic acid, imido acid, or methidoic acid are preferred. Specific examples of suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, etc. Specific examples of the acid generators include those described in paragraphs

[0122] to

[0142] of Japanese Patent Publication No. 2008-111103, Japanese Patent Publication No. 2018-5224, and Japanese Patent Publication No. 2018-25789. When the resist composition of the present invention contains the acid generator, its content is preferably 0 to 200 parts by mass, and more preferably 0.1 to 100 parts by mass, per 100 parts by mass of the base polymer. Furthermore, since the onium salt of the present invention functions as a photoacid generator, it is not essential to separately incorporate the other acid generators mentioned above. 【0227】 When the resist composition of the present invention is of the positive type, the difference in dissolution rate between the exposed and unexposed areas can be further increased by incorporating a dissolution inhibitor, thereby further improving the resolution. Specific examples of the dissolution inhibitor include compounds in which the hydrogen atoms of the phenolic hydroxyl groups of a compound having a molecular weight of preferably 100 to 1000, more preferably 150 to 800, and containing two or more phenolic hydroxyl groups in the molecule are substituted with acid-unstable groups in a total proportion of 0 to 100 mol%, or compounds in which the hydrogen atoms of the carboxyl groups of a compound containing a carboxyl group in the molecule are substituted with acid-unstable groups in an average total proportion of 50 to 100 mol%. Specifically, examples include compounds in which the hydrogen atoms of the hydroxyl group or carboxyl group of bisphenol A, trisphenol, phenolphthalein, cresol novolac, naphthalenecarboxylic acid, adamantanecarboxylic acid, and cholic acid are substituted with acid-unstable groups, as described, for example, in paragraphs

[0155] to

[0178] of Japanese Patent Application Publication No. 2008-122932. 【0228】 When the chemically amplified resist composition of the present invention is of the positive type and contains the dissolution inhibitor, the content thereof is preferably 0 to 50 parts by mass, and more preferably 5 to 40 parts by mass, per 100 parts by mass of the base polymer. The dissolution inhibitor may be used alone or in combination of two or more types. 【0229】 On the other hand, if the chemically amplified resist composition of the present invention is negative type, a negative type pattern can be obtained by adding a crosslinking agent to reduce the dissolution rate of the exposed area. Furthermore, the chemically amplified resist composition of the present invention can be negative type in organic solvent development even without the presence of a crosslinking agent. 【0230】 Specific examples of the crosslinking agent include epoxy compounds, melamine compounds, guanamine compounds, glycoluryl compounds or urea compounds, isocyanate compounds, azide compounds, and compounds containing double bonds such as alkenyloxy groups, which are substituted with at least one group selected from methylol, alkoxymethyl, and acyloxymethyl groups. These may be used as additives or introduced as pendant groups into the polymer side chains. Compounds containing hydroxyl groups can also be used as crosslinking agents. 【0231】 Specific examples of the epoxy compounds mentioned above include tris(2,3-epoxypropyl) isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether. 【0232】 Specific examples of the melamine compounds include hexamethylmelamine, hexamethoxymethylmelamine, compounds in which 1 to 6 methylol groups of hexamethylmelamine are methoxymethylated or mixtures thereof, hexamethoxyethylmelamine, hexaacyloxymethylmelamine, and compounds in which 1 to 6 methylol groups of hexamethylmelamine are acyloxymethylated or mixtures thereof. 【0233】 Specific examples of the guanamine compounds include tetramethylolguanamine, tetramethoxymethylguanamine, compounds in which 1 to 4 methylol groups of tetramethylolguanamine are methoxymethylated or mixtures thereof, tetramethoxyethylguanamine, tetraacyloxyguanamine, and compounds in which 1 to 4 methylol groups of tetramethylolguanamine are acyloxymethylated or mixtures thereof. 【0234】 Specific examples of the glycoluryl compounds include tetramethylol glycoluryl, tetramethoxy glycoluryl, tetramethoxymethyl glycoluryl, compounds in which 1 to 4 methylol groups of tetramethylol glycoluryl are methoxymethylated or mixtures thereof, and compounds in which 1 to 4 methylol groups of tetramethylol glycoluryl are asyloxymethylated or mixtures thereof. Specific examples of the urea compounds include tetramethylolurea, tetramethoxymethylurea, compounds in which 1 to 4 methylol groups of tetramethylolurea are methoxymethylated or mixtures thereof, and tetramethoxyethylurea. 【0235】 Specific examples of the isocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate. 【0236】 Specific examples of the aforementioned azide compounds include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide. 【0237】 Specific examples of compounds containing the aforementioned alkenyloxy group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, and trimethylolpropane trivinyl ether. 【0238】 If the chemically amplified resist composition of the present invention is of the negative type and contains the crosslinking agent, the content of the crosslinking agent is preferably 0.1 to 50 parts by mass, and more preferably 1 to 40 parts by mass, per 100 parts by mass of the base polymer. The crosslinking agent may be used alone or in combination of two or more types. 【0239】 The water-repellent enhancer improves the water repellency of the resist film surface and can be used in immersion lithography without a topcoat. Preferred water-repellent enhancers include polymers containing alkyl fluoride, polymers containing 1,1,1,3,3,3-hexafluoro-2-propanol residues of a specific structure, and those exemplified in Japanese Patent Publication No. 2007-297590 and Japanese Patent Publication No. 2008-111103 are more preferred. The water-repellent enhancer needs to be soluble in an alkaline developer or an organic solvent developer. The aforementioned water-repellent enhancer having a specific 1,1,1,3,3,3-hexafluoro-2-propanol residue exhibits good solubility in the developer. As a water-repellent enhancer, polymers containing repeating units including amino groups or amine salts are highly effective in preventing acid evaporation in the PEB and thus preventing poor hole pattern opening after development. When the chemically amplified resist composition of the present invention contains the water-repellency improving agent, its content is preferably 0 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the base polymer. The water-repellency improving agent may be used alone or in combination of two or more types. It may be used in this way. 【0240】 Specific examples of the aforementioned acetylene alcohols include those described in paragraphs

[0179] to

[0182] of Japanese Patent Publication No. 2008-122932. When the chemically amplified resist composition of the present invention contains the aforementioned acetylene alcohols, the content is preferably 0 to 5 parts by mass per 100 parts by mass of the base polymer. The aforementioned acetylene alcohols may be used individually or in combination of two or more types. 【0241】 [Pattern formation method] When the chemically amplified resist composition of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied. For example, a specific example of a pattern formation method is a method that includes the steps of forming a resist film on a substrate using the chemically amplified resist composition of the present invention as described above, exposing the resist film with high-energy rays, and developing the exposed resist film using a developer. This example of a pattern formation method is the pattern formation method of the present invention. 【0242】 With the pattern formation method of the present invention, since the chemically amplified resist composition of the present invention is used, pattern formation can be performed with excellent LWR, CDU, EL, DOF, MEEF, etc., i.e., with excellent lithography performance. 【0243】 The pattern formation method of the present invention will be described in more detail below, but the pattern formation method of the present invention is not limited to the examples shown below. 【0244】 First, the chemically amplified resist composition of the present invention is applied to a substrate for integrated circuit manufacturing (e.g., Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, and organic anti-reflective coatings, etc.) or a substrate for mask circuit manufacturing (e.g., Cr, CrO, CrON, MoSi2, and SiO2, etc.) by an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, and doctor coating, so that the coating film thickness is preferably 0.01 to 2 μm. The resulting coating film is then pre-baked on a hot plate, preferably at 60 to 150°C for 10 seconds to 30 minutes, more preferably at 80 to 120°C for 30 seconds to 20 minutes, to form a resist film. 【0245】 Next, the resist film is exposed using a high-energy beam. Specific examples of the high-energy beam include ultraviolet light, far-ultraviolet light, EB, EUV with wavelengths of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. For example, as the high-energy beam, an ArF excimer laser beam with a wavelength of 193 nm, a KrF excimer laser beam with a wavelength of 248 nm, an electron beam, or extreme ultraviolet light with wavelengths of 3 to 15 nm can be used. When using ultraviolet light, far-ultraviolet light, EUV, X-rays, soft X-rays, excimer laser light, gamma rays, synchrotron radiation, etc. as the high-energy beam, the exposure amount is preferably 1 to 200 mJ / cm², either directly or using a mask to form the desired pattern. 2 To the extent, more preferably 10 to 100 mJ / cm² 2 Irradiate to the extent of [a certain degree]. When using EB as the high-energy beam, the exposure dose is preferably 0.1 to 300 μC / cm². 2 To a degree, more preferably 0.5 to 200 μC / cm² 2 The pattern is drawn either directly or using a mask to form the desired pattern. The chemically amplified resist composition of the present invention is particularly suitable for fine patterning using high-energy rays, including KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, gamma rays, and synchrotron radiation, and is especially suitable for fine patterning using EB or EUV. 【0246】 In addition to conventional exposure methods, immersion exposure can also be performed by interposing a liquid with a refractive index of 1.0 or higher between the resist film and the projection lens. In this case, a protective film insoluble in water can also be used. 【0247】 The aforementioned water-insoluble protective film is used to prevent leaching from the resist film and to improve the water-repellent properties of the film surface, and there are two main types. One is an organic solvent-removable type that requires removal before alkaline aqueous solution development using an organic solvent that does not dissolve the resist film, and the other is an alkaline aqueous solution-soluble type that is soluble in alkaline developer and removes the protective film along with the soluble parts of the resist film. The latter is particularly preferably based on a polymer having a 1,1,1,3,3,3-hexafluoro-2-propanol residue that is insoluble in water and soluble in alkaline developer, and dissolved in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixture thereof. Alternatively, the aforementioned water-insoluble and alkaline developer-soluble surfactant can be dissolved in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixture thereof. 【0248】 After exposure, PEB may be performed on a hot plate or in an oven, preferably at 30-150°C for 10 seconds to 30 minutes, more preferably at 50-120°C for 30 seconds to 20 minutes, or PEB may not be performed at all. 【0249】 After exposure or PEB, the resist film exposed to light is developed using a developer solution containing preferably 0.1 to 10% by mass, more preferably 2 to 5% by mass, of an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide, for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by conventional methods such as the dip method, puddle method, or spray method, thereby forming the desired pattern on the resist film. In the case of a positive-type chemically amplified resist composition, the parts irradiated with light dissolve in the developer solution, while the parts that were not exposed do not dissolve, and the desired positive-type pattern is formed on the substrate. In the case of a negative-type chemically amplified resist composition, the opposite is true: the parts irradiated with light become insoluble in the developer solution, while the parts that were not exposed dissolve. 【0250】 Negative patterns can also be obtained by organic solvent development using a positive-type chemically amplified resist composition containing a base polymer with an acid-unstable group. Specific examples of developers used in this process include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotate, and ethyl crotate. Examples include methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate. These organic solvents may be used individually or in mixtures of two or more. 【0251】 At the end of development, rinsing is performed. A solvent that mixes with the developer but does not dissolve the resist film is preferred as the rinsing solution. Preferred solvents include C3-C10 alcohols, C8-C12 ether compounds, C6-C12 alkanes, alkenes, alkynes, or aromatic solvents. 【0252】 Specific examples of the C3-C10 alcohols include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, and 3-hexanol. Examples include 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, and cyclohexanol, 1-octanol, etc. 【0253】 Specific examples of the ether compounds having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, disec-pentyl ether, di-tert-pentyl ether, and di-n-hexyl ether. 【0254】 Specific examples of the C6-C12 alkanes include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, and cyclononane. Specific examples of the C6-C12 alkenes include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, and cyclooctene. Specific examples of the C6-C12 alkynes include hexine, heptine, and octine. 【0255】 Specific examples of the aromatic solvents mentioned above include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene. 【0256】 Rinsing can reduce the occurrence of resist pattern deformation and defects. However, rinsing is not always necessary, and omitting it can reduce the amount of solvent used. 【0257】 The developed hole patterns and trench patterns can also be shrunk using techniques such as thermal flow, RELACS, or DSA. A shrinking agent is applied to the hole pattern, and crosslinking of the shrinking agent occurs on the surface of the resist film due to the diffusion of an acid catalyst from the resist film during baking, causing the shrinking agent to adhere to the side walls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the baking time is preferably 10 to 300 seconds, during which excess shrinking agent is removed and the hole pattern is reduced in size. [Examples] 【0258】 The present invention will be specifically described below using synthesis examples, examples, and comparative examples, but the present invention is not limited to these. The following apparatus was used. • MALDI TOF-MS: S3000 manufactured by JEOL Ltd. 【0259】 [1] Synthesis of onium salts [Synthesis Example 1-1] Synthesis of Onium Salt PAG-1 [ka] 【0260】 (1) Synthesis of intermediate In-1 Under a nitrogen atmosphere, the starting materials SM-1 (18.0 g), oxanyl chloride (15.1 g), DMF (N,N-dimethylformamide) (0.2 g), and methylene chloride (100 g) were added to the reaction vessel. The temperature in the reaction vessel was raised to 35°C and aged for 3 hours. After aging, the mixture was cooled to room temperature, and the solvent was removed by distillation to obtain a solid. The obtained solid was dissolved in methylene chloride (60 g), and then the starting materials SM-2 (17.2 g) and pyridine (3.1 g) were added, and the mixture was cooled in an ice bath. After the addition, the temperature was raised to room temperature and aged for 12 hours. After aging, water was added to stop the reaction. Next, the mixture was treated with a normal aqueous system, and the solvent was removed by distillation. Subsequently, the residue was washed with diisopropyl ether to obtain 30.8 g of intermediate In-1 as crystals (yield 98%). 【0261】 (2) Synthesis of PAG-1 Under a nitrogen atmosphere, intermediate In-1 (30.8g), starting material SM-3 (21.5g), methylene chloride (100g), and water (50g) were mixed and stirred for 15 minutes. The organic layer was then separated, washed with water, and concentrated under reduced pressure. Diisopropyl ether (50g) was added to the concentrate, and crystallization was performed to obtain 37.4g of the target product, onium salt PAG-1, as white crystals (yield 94%). The measurement results for the obtained onium salt PAG-1 are as follows. MALDI TOF-MS: POSITIVE M+ 319 (C 22 H 23 S + equivalent) NEGATIVE M-478 (C 22 H 24 NO 9S - equivalent) 【0262】 [Synthesis Examples 1-2 to 1-10] Synthesis of Onium Salts PAG-2 to PAG-10 Using corresponding raw materials and known organic synthesis reactions, onium salts PAG-2 to PAG-10, represented by the following formulas, were synthesized. 【0263】 [ka] 【0264】 [2] Polymer synthesis The polymer used in the chemically amplified resist composition of the present invention was synthesized by the method described below. The Mw of the obtained polymer was measured as a polystyrene equivalent value by GPC using THF as the solvent. 【0265】 [Synthesis Example 2-1] Synthesis of Polymer P-1 Under a nitrogen atmosphere, α-methacrylate-oxy-γ-butyrolactone (32.5 g), 3-hydroxyadamantyl methacrylate (12.9 g), 1-ethylcyclopentyl methacrylate (54.6 g), and dimethyl 2,2'-azobisisobutyrate (6.27 g) were dissolved in PGMEA (155 g) to prepare a solution. This solution was added dropwise over 5 hours to PGMEA (78 g) stirred at 80°C under a nitrogen atmosphere. After the addition was complete, the mixture was stirred for 2 hours while maintaining the 80°C temperature, cooled to room temperature, and then the reaction solution was added dropwise to methanol (2,000 g). The precipitated solid was filtered off and vacuum-dried at 50°C for 20 hours to obtain polymer P-1 as a white powder. The yield was 82 g, and the yield rate was 82%. [ka] 【0266】 [Synthesis Example 2-2] Synthesis of Polymer P-2 Polymer P-2, as shown below, was produced using the same method as in Synthesis Example 2-1, except that the type of monomer and the mixing ratio were changed. [ka] 【0267】 [3] Preparation and evaluation of chemically amplified resist compositions [Examples 1-1 to 1-14, Comparative Examples 1-1 to 1-8] (1) Preparation of chemically amplified resist composition A chemically amplified resist composition was prepared by dissolving a predetermined component selected from the onium salts (PAG-1 to PAG-10), comparative photoacid generators (cPAG-1 to cPAG-8), polymers (P-1, P-2), quenchers (Q-1 to Q-4), and fluorine atom-containing polymer (SF-1) of the present invention in a solvent containing 0.01% by mass of surfactant A (manufactured by Omnova) in the composition shown in Table 1 below, and filtering the solution through a 0.2 μm Teflon® filter. 【0268】 The solvent, comparative photoacid generators (cPAG-1 to cPAG-8), quenchers (Q-1 to Q-4), fluorine atom-containing polymer (SF-1), and surfactant A are as follows. 【0269】 ·solvent: PGMEA (Propylene Glycol Monomethyl Ether Acetate) GBL (γ-butyrolactone) 【0270】 • Comparative photoacid generators: cPAG-1 to cPAG-8 [ka] 【0271】 • Quencher: Q-1~Q-4 [ka] 【0272】 • Fluorine atom-containing polymer: SF-1 [ka] 【0273】 • Surfactant A: 3-methyl-3-(2,2,2-trifluoroethoxymethyl)oxetane-tetrahydrofuran-2,2-dimethyl-1,3-propanediol copolymer (manufactured by Omnova) [ka] a:(b+b'):(c+c')=1:4~7:0.01~1 (molar ratio) Mw=1500 【0274】 (2) ArF lithography evaluation A resist composition prepared above was spin-coated onto a substrate for a tri-layer process, on which a Shin-Etsu Chemical Co., Ltd. spin-on carbon film ODL-180 (carbon content 80% by mass) was deposited to a thickness of 180 nm on a silicon substrate, and a silicon-containing spin-on hard mask SHB-A941 (silicon content 43% by mass) was deposited on the same to a thickness of 35 nm. The resist composition was then baked at 100°C for 60 seconds using a hot plate to form a resist film with a thickness of 100 nm. The resist film was then subjected to an ArF excimer laser immersion scanner (ASML XT-1900Gi, N A Using a polarity of 1.35, 3 / 4 Annular, and XY polarization, exposure was performed on a wafer with dimensions of 45 nm and a pitch of 110 nm (CH pattern), varying the exposure dose and focus (exposure dose pitch: 1 mJ / cm²). 2 The process was carried out while adjusting the focus pitch (0.025 μm). After exposure, PEB was performed at 95°C for 60 seconds. Water was used as the immersion solution. Subsequently, paddle development was performed with n-butyl acetate for 30 seconds, rinsed with 4-methyl-2-pentanol, and spin-dried to obtain a negative-type pattern, the CH pattern. The obtained CH pattern was observed using a Hitachi High-Tech Corporation measuring SEM (CG-5000), and the sensitivity, CDU, and MEEF were evaluated according to the method described below. The results are shown in Table 1. The F content in the photoacid generator anion is also shown in Table 1. 【0275】 [F content in photoacid-generating anion] The mass percentage of fluorine atoms contained in the anionic structure of the photoacid generator is shown. 【0276】 [Sensitivity evaluation] In terms of sensitivity, the optimal exposure dose Eop(mJ / cm²) to obtain an LS pattern with a hole pitch of 104nm and a hole diameter of 52nm is required. 2 We calculated this value and defined it as the sensitivity. 【0277】 [CDU Rating] The CH patterns obtained by irradiation with Eop were measured at 10 locations within the same exposure shot (9 CH patterns per location), and the CDU was calculated as three times the standard deviation (σ) (3σ) from these results. The smaller this value, the better the CDU of the CH pattern. 【0278】 [MEEF rating] While keeping the pitch fixed, the mask dimensions were changed, and the line width of each pattern illuminated by Eop was observed. The slope between the mask dimensions and the pattern line width was defined as MEEF. A MEEF of 3.6 or less was considered good. 【0279】 [Table 1] 【0280】 As shown in Table 1, the chemically amplified resist composition containing the onium salt of the present invention as a photoacid generator exhibited good sensitivity, excellent CDU and MEEF, and was deemed suitable as a material for ArF immersion lithography. On the other hand, the resist composition using a conventional photoacid generator (comparative example) showed insufficient sensitivity, MEEF, or CDU. From the above, it was demonstrated that the chemically amplified resist composition of the present invention is useful for ArF immersion lithography. 【0281】 [4] Preparation and evaluation of chemically amplified resist compositions [Examples 2-1 to 2-12, Comparative Examples 2-1 to 2-8] (1) Preparation of chemically amplified resist composition A chemically amplified resist composition was prepared by dissolving a predetermined component selected from the onium salts (PAG-1 to PAG-10), comparative photoacid generators (cPAG-1 to cPAG-8), polymer (P-1), quencher (Q-1 to Q-4), fluorine atom-containing polymer (SF-1), and other photoacid generators: PAG-A to PAG-B, in a solvent containing 0.01% by mass of surfactant A (manufactured by Omnova) in the composition shown in Table 2 below, and filtering the solution through a 0.2 μm Teflon® filter. 【0282】 Other photoacid generators: PAG-A~PAG-B [ka] 【0283】 (2) ArF lithography evaluation A resist composition prepared above was spin-coated onto a substrate for a tri-layer process, on which a Shin-Etsu Chemical Co., Ltd. spin-on carbon film ODL-180 (carbon content 80% by mass) was deposited to a thickness of 180 nm on a silicon substrate, and a silicon-containing spin-on hard mask SHB-A941 (silicon content 43% by mass) was deposited on the same to a thickness of 35 nm. The resist composition was then baked at 100°C for 60 seconds using a hot plate to form a resist film with a thickness of 100 nm. The resist film was then subjected to an ArF excimer laser immersion scanner (ASML XT-1900Gi, N A Using a dipole (=1.20), a line-and-space pattern (LS pattern) with dimensions of 50 nm and a pitch of 100 nm on the wafer was exposed, varying the exposure dose and focus (exposure dose pitch: 1 mJ / cm²). 2 The process was carried out while adjusting the focus pitch (0.025 μm). After exposure, PEB was performed at 105°C for 60 seconds. Water was used as the immersion solution. Subsequently, paddle development was performed with a 2.38% TMAH aqueous solution for 30 seconds, rinsed with pure water, and spin-dried to obtain a positive-type LS pattern. The obtained LS pattern was observed using a Hitachi High-Tech Corporation measuring SEM (CG-5000), and the sensitivity and LWR were evaluated according to the method described below. The results are shown in Table 2. 【0284】 [Sensitivity evaluation] In terms of sensitivity, the optimal exposure dose Eop(mJ / cm²) for obtaining an LS pattern with a pitch of 100nm and a line width of 50nm is... 2 We calculated this value and defined it as the sensitivity. 【0285】 [LWR rating] For each line in the obtained line-and-space pattern, the CD width was measured at 32 points, and the line widths of 11 lines were measured from a single SEM image. The variation in these CD widths was defined as the LWR. A smaller LWR value indicates better dimensional uniformity. 【0286】 [Table 2] 【0287】 The results shown in Table 1 demonstrate that the chemically amplified resist composition containing the onium salt of the present invention as a photoacid generator exhibits good sensitivity and excellent LWR, making it suitable as a material for ArF immersion lithography. On the other hand, the resist composition using a conventional photoacid generator (comparative example) showed insufficient sensitivity or LWR. From the above, it is shown that the chemically amplified resist composition of the present invention is useful for ArF immersion lithography. 【0288】 This specification includes the following inventions: 【0289】 [1]: An onium salt characterized by being represented by the following general formula (A). [ka] [In the formula, m1 is an integer between 1 and 4. m2 is either 1 or 2.] R 1Each of these is independently a hydrogen atom, a C1-C20 hydrocarbyl group which may contain a heteroatom, and an electron-withdrawing group, and the electron-withdrawing group is a halogen atom other than a fluorine atom, a cyano group, a nitro group, and a C1-C20 hydrocarbyloxy group, hydrocarbylthio group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, hydrocarbylsulfonyl group, and hydrocarbyloxysulfonyl group which may contain a heteroatom, and the R 1 At least one of them is the aforementioned electron-withdrawing group. L A and L B Each of these is independently a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, an oxalyl (-C(=O)C(=O)-) bond, or a 1-10 carbon dioxide hydrocarbylene group which may contain a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, or a carbamate bond. W 1 This is a hydrocarbylene group having 3 to 40 carbon atoms that does not contain an aromatic ring and contains an alicyclic structure, and may contain a heteroatom. However, the aforementioned W 1 is adjacent to L A or L B It has two bonding bonds on the carbon atoms forming the alicyclic structure. 2 This refers to a hydrocarbyl group having 3 to 40 carbon atoms that does not contain an aromatic ring but contains an alicyclic structure, and may also contain a heteroatom. Z + This is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2). [ka] (In the formula, R ct1 ~R ct5 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom. Also, Rct1 and R ct2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. 【0290】 [2]: The above W 1 and W 2 The onium salt according to [1] above, characterized in that at least one of them contains a lactone ring structure or a sultone ring structure. 【0291】 [3]: The above R 1 The onium salt according to [1] or [2] above, characterized in that at least one of them is a cyano group or a nitro group. 【0292】 [4]: The onium salt described in any of [1] to [3] above, characterized in that it is represented by the following general formula (A-1). [ka] (In the formula, m12 is an integer between 0 and 3. R 1 , L B , W 1 , W 2 and Z + The same as above. R 3 R 1 Same as above. L A2 These are ether bonds, ester bonds, amide bonds, sulfonic acid ester bonds, sulfonamide bonds, carbonate bonds, or carbamate bonds. 【0293】 [5]: A photoacid generator characterized by comprising any of the onium salts described in [1] to [4] above. 【0294】 [6]: A chemically amplified resist composition, characterized in that (A) it contains the photoacid generator described in [5] above. 【0295】 [7]: The chemical amplification resist composition according to [6], characterized in that the chemical amplification resist composition further comprises a (B) base polymer having repeating units having acid-unstable groups. 【0296】 [8]: The chemical amplification resist composition according to [7] above, characterized in that the repeating unit having the acid-unstable group is represented by the following general formula (B1). [ka] (In the formula, R A R is a hydrogen atom or a methyl group. AL It is an acid-unstable group. 【0297】 [9]: The chemical amplification resist composition according to [7] or [8] above, characterized in that the (B) base polymer comprises at least one selected from the following general formula (B2), the following general formula (B3), and the following general formula (B4). [ka] (In the formula, R A R is a hydrogen atom or a methyl group. 11 and R 12 Each of these is independently either a hydrogen atom or a hydroxyl group. 13 R is a substituent having a lactone structure or a substituent having a sultone structure. 14 (This is a hydrogen atom, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or a monovalent fluoroalcohol-containing substituent having 1 to 15 carbon atoms.) 【0298】

[10] : The chemical amplification resist composition according to any one of [6] to [9] above, characterized in that the chemical amplification resist composition further comprises (C) an organic solvent. 【0299】

[11] : The chemical amplification resist composition according to any one of [6] to

[10] above, characterized in that the chemical amplification resist composition further comprises a (D) fluorine atom-containing polymer comprising at least one selected from repeating units represented by the following general formula (D1), repeating units represented by the following general formula (D2), repeating units represented by the following general formula (D3), and repeating units represented by the following general formula (D4). [ka] (In the formula, R B This is either a hydrogen atom or a methyl group. R 21 and R 22 Each of these is independently either a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. R 23 This is a single-bonded, linear, or branched hydrocarbylene group having 1 to 5 carbon atoms. R 24 , R 25 and R 26 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group, a C1-C15 fluorinated hydrocarbyl group, a C2-C15 acyl group, or an acid-unstable group. 24 , R 25 and R 26 When the group is a hydrocarbyl group or a fluorinated hydrocarbyl group, some of these -CH2- groups may be substituted with ether bonds or carbonyl groups. R 27 This is a (k+1) valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1) valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. k is an integer between 1 and 3. X 21 These are, independently, a single bond, an ester bond, an ether bond, an amide bond, or a phenylene bond. X 22Each of these is independently a single bond or a hydroxylylene group having 1 to 20 carbon atoms when p is 1, and a trivalent hydrocarbon group having 1 to 20 carbon atoms when p is 2, and the hydroxylylene group and the trivalent hydrocarbon group may contain at least one selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a halogen atom. p is an integer, either 1 or 2. X 23 These are, independently, a single bond, an ester bond, an ether bond, an amide bond, a sulfonic acid ester bond, a urethane bond, a thiourethane bond, and a urea bond. Ar is a group derived from benzene or naphthalene. R 28 Each of these is independently a hydrogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 6 carbon atoms, a hydroxyl group, a carboxyl group, a halogen atom, a cyano group, or a nitro group. m is an integer between 1 and 5. 【0300】

[12] : The chemical amplification resist composition according to any one of [6] to

[11] above, characterized in that the chemical amplification resist composition further comprises (E) a quencher. 【0301】

[13] : The chemical amplification resist composition according to any one of [6] to

[12] above, characterized in that the chemical amplification resist composition further comprises (G) a surfactant. 【0302】

[14] : A pattern formation method comprising the steps of forming a resist film on a substrate using a chemically amplified resist composition described in any of [6] to

[13] above, exposing the resist film with a high-energy beam, and developing the exposed resist film using a developer. 【0303】

[15] : The pattern formation method according to

[14] above, characterized in that the high-energy beam is a KrF excimer laser beam, an ArF excimer laser beam, an electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm. 【0304】 It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

[Claim 1] An onium salt characterized by being represented by the following general formula (A-1). 【Chemistry 1】 [In the formula, m12 is an integer between 0 and 2.] R １ Each of these is independently a hydrogen atom, a C1-C20 hydrocarbyl group which may contain a heteroatom, and an electron-withdrawing group, and the electron-withdrawing group is a halogen atom other than a fluorine atom, a cyano group, a nitro group, and a C1-C20 hydrocarbyloxy group, hydrocarbylthio group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, hydrocarbylsulfonyl group, and hydrocarbyloxysulfonyl group which may contain a heteroatom. R ３ This is either a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a heteroatom. L Ａ２ These are ether bonds, ester bonds, amide bonds, sulfonic acid ester bonds, sulfonamide bonds, carbonate bonds, or carbamate bonds. L Ｂ These are, independently, a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, or an oxalyl (-C(=O)C(=O)-) bond. W １ is a hydrocarbylene group having 3 to 40 carbon atoms and containing an alicyclic structure and not containing an aromatic ring, and may contain a hetero atom. However, the above-mentioned W １ has two bonds with the adjacent LA2 or the above-mentioned L Ｂ on a carbon atom forming the alicyclic structure. W ２ is a hydrocarbyl group having 3 to 40 carbon atoms and containing an alicyclic structure and not containing an aromatic ring, and may contain a hetero atom. However, when L Ａ２ is an ester bond represented by *-O-C(=O)-** (* and ** are bonds with the W ２ side and the SO ３－ side, respectively), W ２ is any one of the following formulas (T1) to (T4). Z ＋ This is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2). However, the sulfonic acid anion portion of the onium salt may be any of the following formulas (T5). 【Chemistry 2】 (In the formula, R ｃｔ１ ~R ｃｔ５ Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ｃｔ１ and R ｃｔ２ However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. 【Transformation 3】 (T1) 【Chemistry 4】 (T2) 【Transformation 5】 (T3) 【Transformation 6】 (T4) (In the above formula, * represents a bond with L A2. Furthermore, if an asymmetric carbon is present and an enantiomer or diastereomer exists, the above formula represents those isomers.) 【Transformation 7】 (T5) [Claim 2] The aforementioned W １ and W ２ The onium salt according to claim 1, characterized in that at least one of them includes a lactone ring structure or a sultone ring structure. [Claim 3] The aforementioned R １ The onium salt according to claim 1, characterized in that at least one of them is a cyano group or a nitro group. [Claim 4] A photoacid generator characterized by comprising an onium salt as described in any one of claims 1 to 3. [Claim 5] A chemically amplified resist composition, characterized in that it comprises (A) the photoacid generator described in claim 4. [Claim 6] The chemical amplification resist composition according to claim 5, characterized in that the chemical amplification resist composition further comprises a (B) base polymer containing repeating units having acid-unstable groups. [Claim 7] The chemically amplified resist composition according to claim 6, characterized in that the repeating unit having the acid-unstable group is represented by the following general formula (B1). 【Transformation 8】 (In the formula, R Ａ R is a hydrogen atom or a methyl group. ＡＬ It is an acid-unstable group. [Claim 8] The chemical amplification resist composition according to claim 6, characterized in that the (B) base polymer comprises at least one selected from the following general formula (B2), the following general formula (B3), and the following general formula (B4). 【Chemistry 9】 (In the formula, R Ａ R is a hydrogen atom or a methyl group. １１ and R １２ Each of these is independently either a hydrogen atom or a hydroxyl group. １３ R is a substituent having a lactone structure or a substituent having a sultone structure. １４ (This is a hydrogen atom, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or a substituent containing a monovalent fluoroalcohol having 1 to 15 carbon atoms.) [Claim 9] The chemical amplification resist composition according to claim 5, characterized in that the chemical amplification resist composition further comprises (C) an organic solvent. [Claim 10] The chemical amplification resist composition according to claim 5, characterized in that the chemical amplification resist composition further comprises a (D) fluorine atom-containing polymer comprising at least one selected from the following general formula (D1), the following general formula (D2), the following general formula (D3), and the following general formula (D4). 【Chemistry 10】 (In the formula, R Ｂ This is either a hydrogen atom or a methyl group. R ２１ and R ２２ Each of these is independently either a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. R ２３ This is a single-bonded, linear, or branched hydrocarbylene group having 1 to 5 carbon atoms. R ２４ , R ２５ and R ２６ Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group, a C1-C15 fluorinated hydrocarbyl group, a C2-C15 acyl group, or an acid-unstable group. ２４ , R ２５ and R ２６ When it is a hydrocarbyl group or a fluorinated hydrocarbyl group, these -CH ２ A portion of the - may be substituted with an ether bond or a carbonyl group. R ２７ This is a (k+1) valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1) valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. k is an integer between 1 and 3. X ２１ These are, independently, a single bond, an ester bond, an ether bond, an amide bond, or a phenylene bond. X ２２ Each of these is independently a single bond or a hydroxylylene group having 1 to 20 carbon atoms when p is 1, and a trivalent hydrocarbon group having 1 to 20 carbon atoms when p is 2, and the hydroxylylene group and the trivalent hydrocarbon group may contain at least one selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a halogen atom. p is an integer, either 1 or 2. X ２３ These are, independently, a single bond, an ester bond, an ether bond, an amide bond, a sulfonic acid ester bond, a urethane bond, a thiourethane bond, and a urea bond. Ar is a group derived from benzene or naphthalene. R ２８ Each of these is independently a hydrogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 6 carbon atoms, a hydroxyl group, a carboxyl group, a halogen atom, a cyano group, or a nitro group. m is an integer between 1 and 5. [Claim 11] The chemical amplification resist composition according to claim 5, characterized in that the chemical amplification resist composition further comprises (E) a quencher. [Claim 12] The chemical amplification resist composition according to claim 5, characterized in that the chemical amplification resist composition further comprises (G) a surfactant. [Claim 13] A pattern formation method comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition described in claim 5; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer. [Claim 14] The pattern formation method according to claim 13, characterized in that the high-energy beam used is KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

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