Onium salt type monomer, polymer, chemically amplified resist composition, and patterning method

Abstract

This invention provides a sulfonium salt type monomer used in a chemically amplified resist composition that exhibits excellent solvent solubility, high sensitivity, high contrast, and superior lithography performance such as LWR, CDU, EL, and DOF in photolithography using high-energy rays; a polymer containing repeating units derived from the sulfonium salt type monomer; a chemically amplified resist composition containing the polymer; and a method for pattern formation using the chemically amplified resist composition. [Solution] An onium salt type monomer represented by the following formula (A). TIFF2026084674000267.tif2597

Description

[Technical Field]

[0001] The present invention relates to onium salt type monomers, polymers, chemically amplified resist compositions, and patterning methods. [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] As miniaturization progresses and approaches the diffraction limit of light, the contrast of light decreases. This decrease in light contrast leads to a reduction in the resolution of hole patterns and trench patterns, as well as a decrease in the focus margin, in positive resist films.

[0004] As patterns become finer, the line width roughness (LWR) of line patterns and the dimensional uniformity (CDU) of hole patterns are becoming problematic. The effects of uneven distribution and aggregation of base polymers and acid generators, as well as the effects of acid diffusion, have been pointed out. Furthermore, LWR tends to increase as the resist film thins, and the degradation of LWR due to thinning as finer patterns progress is becoming a serious problem.

[0005] In resist compositions for EUV lithography, it is necessary to simultaneously achieve high sensitivity, high resolution, and low LWR. Shortening the acid diffusion distance reduces LWR but also lowers sensitivity. For example, lowering the post-exposure bake (PEB) temperature reduces LWR but lowers sensitivity. Increasing the amount of quencher added also reduces LWR but lowers sensitivity. It is necessary to overcome the trade-off relationship between sensitivity and LWR.

[0006] To suppress acid diffusion, resist compounds containing repeating units derived from onium salts of polymerizable unsaturated sulfonic acids have been proposed (Patent Document 1). Such so-called polymer-bound acid generators have the characteristic of very short acid diffusion because polymer-type sulfonic acids are generated upon exposure. Furthermore, sensitivity can be improved by increasing the ratio of the acid generator. In the case of additive-type acid generators, increasing the amount added also increases sensitivity, but in this case the acid diffusion distance also increases. Since acids diffuse non-uniformly, increased acid diffusion degrades LWR and CDU. Polymer-type acid generators can be said to have high capability in balancing sensitivity, LWR, and CDU.

[0007] Because iodine atoms have very high absorption of EUV light at a wavelength of 13.5 nm, the effect of generating secondary electrons from iodine atoms during exposure has been confirmed, and they are attracting attention in EUV lithography. Patent document 2 describes a photoacid generator in which iodine atoms are introduced into an anion, and patent document 3 describes a photoacid generator containing a polymerizable group in which iodine atoms are introduced into an anion. Although some improvement in lithography performance has been confirmed as a result, iodine atoms do not have high solubility in organic solvents, and precipitation in solvents is a concern.

[0008] Patent documents 4 and 5 describe onium salt monomers that generate fluoroalkanesulfonic acid, having acenaphthylene or maleimide as polymerizable groups. Patent document 6 also describes onium salt monomers that generate acenaphthylene sulfonic acid or indenesulfonic acid. While these have improved lithography performance to some extent, there is still room for improvement, and the development of resist materials effective for forming even finer patterns is desired. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 4425776 [Patent Document 2] Patent No. 6720926 [Patent Document 3] Patent No. 6973274 [Patent Document 4] Japanese Patent Publication No. 2024-137079 [Patent Document 5] Japanese Patent Publication No. 2024-112755 [Patent Document 6] International Publication No. 2022 / 172689 [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 and can improve lithography performance such as LWR, CDU, exposure margin (EL), and depth of field (DOF).

[0011] The present invention has been made in view of the above circumstances, and aims to provide a sulfonium salt type monomer used in a chemically amplified resist composition that has excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance such as LWR, CDU, EL, DOF, etc., particularly in photolithography using high-energy beams such as KrF excimer laser light, ArF excimer laser light, electron beam (EB), and EUV; a polymer containing repeating units derived from the sulfonium salt type monomer; a chemically amplified resist composition containing the polymer; and a method for forming a pattern using the chemically amplified resist composition. [Means for solving the problem]

[0012] As a result of diligent research to achieve the above objective, the present inventors have discovered that by using a polymer containing repeating units derived from an onium salt containing an aromatic sulfonic acid anion having acenaphthylene, a fused aromatic compound, as a polymer-bound acid generator, a chemically amplified resist composition can be obtained that exhibits good sensitivity, highly controlled acid diffusion, improved lithography performance such as LWR, CDU, EL, and DOF, high contrast and high resolution, and excellent etching resistance, thereby completing the present invention.

[0013] In other words, the present invention provides the following onium salt type monomers, polymers, chemically amplified resist compositions, and pattern forming methods. 1. An onium salt type monomer represented by the following formula (A). [ka] (In the formula, n1 is 0, 1, 2, 3 or 4. n2 is 0 or 1. n3 is 0, 1, 2, 3 or 4. n4 is 0, 1, 2, 3 or 4. However, when n2 is 0, 0 ≤ n3 + n4 ≤ 4, and when n2 is 1, 0 ≤ n3 + n4 ≤ 6.) R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 1is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom, a hydroxy group, a nitro group, a cyano group, or a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom. When n1 is 2, 3 or 4, each R 1 may be the same as or different from each other, and a plurality of R 1 may combine with each other to form a ring together with the carbon atom to which they are attached. R 2 is a halogen atom other than a fluorine atom, a nitro group, a hydroxy group, a hydrocarbyl group having 1 to 20 carbon atoms, a hydrocarbyloxy group having 1 to 20 carbon atoms, or a hydrocarbylthio group having 1 to 20 carbon atoms, and the hydrocarbyl group, hydrocarbyloxy group, and hydrocarbylthio group may contain a heteroatom other than a fluorine atom. When n4 is 2, 3 or 4, each R 2 may be the same as or different from each other, and a plurality of R 2 may combine with each other to form a ring together with the carbon atom to which they are attached. R F is a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a fluorinated saturated hydrocarbyloxy group having 1 to 6 carbon atoms, or a fluorinated saturated hydrocarbylthio group having 1 to 6 carbon atoms. When n3 is 2, 3 or 4, each R F may be the same as or different from each other. L A and L B are each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, or a carbamate bond. X L1 is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. Z + is an onium cation.) 2. The onium salt type monomer which is represented by the following formula (A1).

Chemical formula

[0014] When pattern formation is performed using a chemically amplified resist composition containing a polymer that includes repeating units functioning as a photoacid generator derived from the onium salt type monomer of the present invention, it is possible to form a resist pattern with high contrast, good sensitivity, and excellent lithography performance such as LWR, CDU, EL, and DOF. [Modes for carrying out the invention]

[0015] The present invention will be described in detail below. In the following description, depending on the structure represented by the chemical formula, an asymmetric carbon may be present, 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.

[0016] [Onium salt type monomer] The onium salt type monomer of the present invention is represented by the following formula (A). [ka]

[0017] In formula (A), n1 is 0, 1, 2, 3, or 4, but is preferably 0, 1, or 2, and more preferably 0 or 1. n2 is 0 or 1. When n2 is 0, it is a benzene ring, and when n2 is 1, it is a naphthalene ring, but from the viewpoint of solvent solubility, it is preferably a benzene ring with n2 being 0. n3 is 0, 1, 2, 3, or 4. n4 is 0, 1, 2, 3, or 4. However, when n2 is 0, 0 ≤ n3 + n4 ≤ 4, and when n2 is 1, 0 ≤ n3 + n4 ≤ 6.

[0018] In formula (A), R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Of these, a hydrogen atom or a methyl group is preferred, and a hydrogen atom is more preferred.

[0019] In formula (A), R 1This is a C1-C20 hydrocarbyl group which may contain a halogen atom, a hydroxyl group, a nitro group, a cyano group, or a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, or a C1-C20 hydrocarbylthio group which may contain a heteroatom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The hydrocarbyl portion of the hydrocarbyl group, hydrocarbyloxy group, and hydrocarbylthio 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; cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, and 4-methylcyclo Examples include cyclic saturated hydrocarbyl groups with 3 to 20 carbon atoms, such as hexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; alkenyl groups with 2 to 20 carbon atoms, such as vinyl, 1-propenyl, 2-propenyl, butenyl, and hexenyl groups; cyclic unsaturated hydrocarbyl groups with 3 to 20 carbon atoms, such as cyclohexenyl groups; aryl groups with 6 to 20 carbon atoms, such as phenyl and naphthyl groups; aralkyl groups with 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; 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 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 cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether 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)-), a haloalkyl group, etc. When n1 is 2, 3 or 4, each R1 may be the same as or different from each other.

[0020] Also, when n1 is 2, 3 or 4, a plurality of R 1 may combine with each other to form a ring together with the carbon atom to which they are attached. Examples of the ring formed at this time include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, an adamantane ring, etc. Further, some or all of the hydrogen atoms in the ring may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and some of -CH2- in the ring may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc. As a result, it may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc.

[0021] In formula (A), R 2 is a halogen atom other than a fluorine atom, a nitro group, a hydroxy group, a hydrocarbyl group having 1 to 20 carbon atoms, a hydrocarbyloxy group having 1 to 20 carbon atoms or a hydrocarbylthio group having 1 to 20 carbon atoms, and the hydrocarbyl group, hydrocarbyloxy group and hydrocarbylthio group may contain a hetero atom other than a fluorine atom. Specific examples of the halogen atom other than a fluorine atom include a chlorine atom, a bromine atom, an iodine atom, etc. The hydrocarbyl moiety of the hydrocarbyl group, hydrocarbyloxy group and hydrocarbylthio group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include R 1Examples of the hydrocarbyl group represented by include, but are not limited to, those similar to those exemplified above. Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as a halogen atom other than an oxygen atom, a sulfur atom, a nitrogen atom, and a fluorine atom, and a part of -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, and a nitrogen atom. As a result, it may contain a hydroxy group, a cyano group, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc. When n4 is 2, 3, or 4, each R 2 may be the same as or different from each other.

[0022] Further, when n4 is 2, 3, or 4, a plurality of R 2 may combine with each other to form a ring together with the carbon atom to which they are attached. The ring is preferably a 5- to 8-membered ring.

[0023] In formula (A), R F is a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a fluorinated saturated hydrocarbyloxy group having 1 to 6 carbon atoms, or a fluorinated saturated hydrocarbylthio group having 1 to 6 carbon atoms. Among these, a fluorine atom, a trifluoromethyl group, a trifluoromethoxy group, or a trifluoromethylthio group is preferable, and a fluorine atom is more preferable. When n3 is 2, 3, or 4, each R F may be the same as or different from each other.

[0024] In formula (A), L A and L B are each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, or a carbamate bond. Among these, a single bond, an ether bond, an ester bond, and a sulfonic acid ester bond are preferable.

[0025] In formula (A), X L1 This is a 1-40 carbon atom hydrocarbylene group which may contain single bonds or heteroatoms. The hydrocarbylene group may be linear, branched, or cyclic, and specific examples include an alkanediyl group and a cyclic saturated hydrocarbylene group. The heteroatoms may include oxygen atoms, nitrogen atoms, sulfur atoms, etc.

[0026] X L1 The following are preferred as C1-C40 hydrocarbylene groups that may contain heteroatoms represented by the formula below. In the formula below, * represents L A and L B This represents a combination of two things. [ka]

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] Of these, X L1 For example, X L -0~X L -22, X L -29~X L -34, and X L -47~X L -58 is preferable.

[0031] As the onium salt type monomer represented by formula (A), the one represented by the following formula (A1) is preferred. [ka] (In the formula, n1, n3, n4, R A , R 1 , R 2 , R F , L A , L B , X L1 and Z + (This is the same as above.)

[0032] As the onium salt type monomer represented by formula (A1), the one represented by the following formula (A2) is preferred. [ka] (In the formula, n1, R A , R 1 , L A , L B , X L1 and Z + (This is the same as above.)

[0033] The anions of the onium salt type monomer represented by formula (A) include, but are not limited to, those listed below. Note that in the following formula, R A This is the same as described above. Furthermore, the bonding positions of the various substituents on the aromatic ring may be interchanged. [ka]

[0034] [ka]

[0035] [ka]

[0036] [ka]

[0037] [ka]

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[0069] [Chemistry]

[0070] [Chemistry]

[0071] In formula (A), Z + is an onium cation. As the onium cation, a sulfonium cation represented by the following formula (Z-1) or an iodonium cation represented by the following formula (Z-2) is preferable. [Chemistry]

[0072] In formulas (Z-1) and (Z-2), R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a hetero atom.

[0073] ... R ct1 ~R ct5 Specific examples of the halogen atom represented by R

[0074] R ct1 ... ~R ct5The hydrocarbyl group represented by may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 30 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group; cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, adamantyl group and other cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms; alkenyl groups having 2 to 30 carbon atoms such as vinyl group, 1-propenyl group, 2-propenyl group, butenyl group, hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 30 carbon atoms such as cyclohexenyl group; aryl groups having 6 to 30 carbon atoms such as phenyl group, naphthyl group, thienyl group; aralkyl groups having 7 to 30 carbon atoms such as benzyl group, 1-phenylethyl group, 2-phenylethyl group; groups obtained by combining these, etc. Among these, an aryl group is preferred. Further, 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, a sulfur atom, a nitrogen atom, a halogen atom, etc., and a part of -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc. As a result, it may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

[0075] Also, R ct1 and R ct2 may combine with each other to form a ring together with the sulfur atom to which they are attached. At this time, specific examples of the structure of the ring include those represented by the following formula, etc.

Chemical formula

[0076] Specific examples of sulfonium cations represented by formula (Z-1) include those described in paragraphs

[0102] to

[0125] of Japanese Patent Publication No. 2024-003744 and those described in paragraphs

[0070] to

[0085] of Japanese Patent Publication No. 2023-169812, but are not limited to these.

[0077] Specific examples of iodonium cations represented by formula (Z-2) include, but are not limited to, those described in paragraph

[0181] of Japanese Patent Application Publication No. 2024-000259.

[0078] Z + As the onium cation represented by the following formula (Z-3), a sulfonium cation represented by the following formula is also preferred. [ka]

[0079] In formula (Z-3), m1 is either 0 or 1. When m1 is 0, it is a benzene ring, and when m1 is 1, it is a naphthalene ring, but from the viewpoint of solvent solubility, it is preferable that m1 is a benzene ring with a value of 0. m2 is either 0 or 1. When m2 is 0, it is a benzene ring, and when m2 is 1, it is a naphthalene ring, but from the viewpoint of solvent solubility, it is preferable that m2 is a benzene ring with a value of 0. m3 is either 0 or 1. When m3 is 0, it is a benzene ring, and when m3 is 1, it is a naphthalene ring, but from the viewpoint of solvent solubility, it is preferable that m3 is a benzene ring with a value of 0.

[0080] In formula (Z-3), m4 is 0, 1, 2, 3, or 4. The more iodine atoms in the cation structure there are, the higher the absorption, especially for EUV. However, this also leads to poor solvent solubility and concerns about precipitation in the resist composition. Therefore, m4 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2.

[0081] In formula (Z-3), m5 is 0, 1, 2, 3, or 4. From the viewpoint of raw material procurement, m5 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2. m6 is 0, 1, 2, 3, 4, 5, or 6. From the viewpoint of raw material procurement, m6 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2. m7 is 0, 1, 2, 3, 4, 5, or 6. From the viewpoint of raw material procurement, m7 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2.

[0082] In formula (Z-3), m8 is 0, 1, or 2. From the viewpoint of raw material procurement, it is preferable that m8 is 0 or 1. m9 is 0, 1, or 2. From the viewpoint of raw material procurement, it is preferable that m9 is 0 or 1. m10 is 0, 1, or 2. From the viewpoint of raw material procurement, it is preferable that m10 is 0 or 1.

[0083] In formula (Z-3), m11 is either 0 or 1. When m11 is 0, it is a benzene ring, and when m11 is 1, it is a naphthalene ring, but from the viewpoint of solvent solubility, a benzene ring with m11 being 0 is preferred.

[0084] In formula (Z-3), m12 is 0, 1, 2, 3, or 4. The more iodine atoms in the cation structure there are, the higher the absorption, especially for EUV. However, this also leads to poor solvent solubility and concerns about precipitation in the resist composition. Therefore, m12 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2.

[0085] In formula (Z-3), m13 is 0, 1, or 2. From the viewpoint of raw material procurement, it is preferable that m13 is 0 or 1. m14 is 0, 1, or 2. From the viewpoint of synthesis, it is preferable that m14 is 0 or 1.

[0086] However, when m1 is 0, 0 ≤ m6 + m9 ≤ 4, and when m1 is 1, 0 ≤ m6 + m9 ≤ 6. When m2 is 0, 0 ≤ m7 + m10 ≤ 4, and when m2 is 1, 0 ≤ m7 + m10 ≤ 6. When m3 is 0, 1 ≤ m4 + m5 + m8 + m14 ≤ 4, and when m3 is 1, 1 ≤ m4 + m5 + m8 + m14 ≤ 6. When m11 is 0, 0 ≤ m12 + m13 ≤ 4, and when m11 is 1, 0 ≤ m12 + m13 ≤ 6. Also, m4 + m12 ≥ 1.

[0087] In formula (Z-3), R F1 ~R F3 Each of these is independently a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a fluorinated saturated hydrocarbyloxy group having 1 to 6 carbon atoms, or a fluorinated saturated hydrocarbylthio group having 1 to 6 carbon atoms. Among these, trifluoromethyl, trifluoromethoxy, and trifluorothiomethoxy groups are preferred. When m5 is 2, 3, or 4, each R F1 They may be the same or different from each other. When m6 is 2, 3, 4, 5 or 6, each R F2 They may be the same or different from each other. When m7 is 2, 3, 4, 5 or 6, each R F3 They may be the same as or different from each other.

[0088] In formula (Z-3), R ct6 ~R ct9 This is a C1-C20 hydrocarbyl group which may contain halogen atoms other than iodine and fluorine atoms, a nitro group, a cyano group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, or a C1-C20 hydrocarbylthio group which may contain a heteroatom. The hydrocarbyl portion of the hydrocarbyl group, hydrocarbyloxy group, and hydrocarbylthio group may be saturated or unsaturated, and may be linear, branched, or cyclic. For example, in the explanation of formula (A), R 1Examples of hydrocarbyl groups represented by the above are similar to those exemplified. Furthermore, some or all of the hydrogen atoms in the hydrocarbyl portion of the hydrocarbyl group, hydrocarbyloxy group and hydrocarbylthio 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, the group 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.

[0089] Also, when m8 is 2, the two R ct6 The two Rs may be identical or different from each other. ct6 These may bond with each other to form a ring with the carbon atom to which they are bonded. When m9 is 2, two R ct7 The two Rs may be identical or different from each other. ct7 These may bond with each other to form a ring with the carbon atom to which they are bonded. When m10 is 2, two R ct8 The two Rs may be identical or different from each other. ct8 These may bond with each other to form a ring with the carbon atoms to which they are bonded. When m13 is 2, two R ct9 The two Rs may be identical or different from each other. ct9They may be bonded to each other to form a ring together with the carbon atoms to which they are bonded. Specific examples of the ring formed at this time include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, an adamantane ring, and the like. Further, some or all of the hydrogen atoms in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, and the like.

[0090] Further, the S in the sulfonium cation represented by the formula (Z-3) + The aromatic rings directly bonded to each other may be bonded to each other to form a ring together with S + Specific examples of the structure of the ring at this time include those represented by the following formula and the like.

Chemical formula

[0091] In the formula (Z-3), L C and L D are each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond or a carbamate bond. Among these, L C is preferably a single bond, an ether bond, an ester bond or a sulfonic acid ester bond, and more preferably an ester bond or a sulfonic acid ester bond. L D is preferably a single bond, an ether bond or an ester bond, and more preferably a single bond.

[0092] In the formula (Z-3), X L2This is a C1-C40 hydrocarbilene group which may contain a single bond or a heteroatom. A specific example of the C1-C40 hydrocarbilene group which may contain a heteroatom is X L1 Examples of hydrocarbylene groups having 1 to 40 carbon atoms that may contain heteroatoms represented by the formula shown are similar to those exemplified, but are not limited to these.

[0093] The sulfonium cation represented by formula (Z-3) is preferably the one represented by formula (Z-3-1) below. [ka] (In the formula, m4~m10, m12~m14, R F1 ~R F3 , R ct6 ~R ct9 , L C , L D and X L2 (This is the same as above.)

[0094] The cation represented by formula (Z-3-1) is preferably the one represented by formula (Z-3-2) below. [ka] (In the formula, m4~m10, R F1 ~R F3 and R ct6 ~R ct8 (This is the same as above.)

[0095] Specific examples of sulfonium cations represented by formula (Z-3) are listed below, but are not limited to these. In the following formula, Me represents a methyl group. [ka]

[0096] [ka]

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[0123] Specific examples of the onium salt type monomer of the present invention include any combination of the anion and cation described above.

[0124] The onium salt type monomer of the present invention can be synthesized, for example, by the same method as the sulfonium salt having a polymerizable anion described in Japanese Patent No. 5201363. However, the above production method is merely an example, and the method for producing the onium salt type monomer of the present invention is not limited thereto.

[0125] The onium salt type monomer of the present invention is useful as a raw material for polymer-type photoacid generators.

[0126] [polymer] The polymer of the present invention contains repeating units derived from an onium salt type monomer represented by formula (A) (hereinafter also referred to as repeating unit A).

[0127] The polymer of the present invention is a polymer-bound photoacid generator that functions as both a photoacid generator and a base polymer in a chemically amplified resist composition. A structural feature of the polymer of the present invention is that it has an acenaphthylene structure in its main chain and an aromatic sulfonic acid anion structure in its side chains. The aromatic sulfonic acid anion structure is more rigid than the fluoroalkanesulfonate structure, thus reducing the acid diffusion distance. On the other hand, acenaphthylene is a polycyclic aromatic hydrocarbon, possessing both rigidity and polymerizability. The presence of an aromatic ring in the main chain makes the main chain of the base polymer rigid, improving the glass transition temperature (Tg) of the base polymer. Introducing such an acenaphthylene structure into the main chain of the polymer suppresses excessive diffusion of the generated acid after exposure. Furthermore, it is conceivable that the interaction of aromatic rings within or between base polymers (π-π stacking effect) causes the base polymer to be arranged regularly, resulting in resistance to pattern collapse in the developer even during fine pattern formation. Furthermore, the acenaphthylene structure exhibits excellent etching resistance even during the etching process after fine pattern formation. Due to these synergistic effects, the polymer of the present invention suppresses excessive diffusion of generated acids, resulting in excellent lithography performance such as LWR for line patterns and CDU for hole patterns, and enabling the formation of patterns that are resistant to pattern deformation. Therefore, it is particularly suitable as a material for chemically amplified positive resist compositions.

[0128] The polymer may contain a repeating unit represented by the following formula (a1) (hereinafter also referred to as repeating unit a1) or a repeating unit represented by the following formula (a2) (hereinafter also referred to as repeating unit a2). [ka]

[0129] In equations (a1) and (a2), R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0130] In formula (a1), X1 This consists of a single bond, a phenylene group, a naphthylene group, and *-C(=O)-OX. 11 - or *-C(=O)-NH-X 11 -The phenylene group or naphthylene group may be substituted with a hydroxyl group, a nitro group, a cyano group, a saturated hydrocarbyl group having 1 to 10 carbon atoms which may contain a fluorine atom, a saturated hydrocarbyloxy group having 1 to 10 carbon atoms which may contain a fluorine atom, or a halogen atom. 11 This is a saturated hydrocarbylene group, phenylene group, or naphthylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. * represents a bond with a carbon atom of the main chain.

[0131] In formula (a2), X 2 The bond is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain. 11 This is a C1-C20 hydrocarbyl group which may contain a halogen atom, a cyano group, a hydroxyl group, a nitro group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. a1 is 0, 1, 2, 3 or 4, preferably 0 or 1. When a1 is 2, 3 or 4, each R 11 They may be the same as or different from each other.

[0132] In formulas (a1) and (a2), AL 1 and AL 2 Each of these is independently an acid-unstable group. Specific examples of the acid-unstable groups include those described in Japanese Patent Publication No. 2013-80033 and Japanese Patent Publication No. 2013-83821.

[0133] Typical examples of the acid-unstable group include those represented by the following formulas (AL-1) to (AL-3). [ka] (In the formula, * represents a coupling.)

[0134] In equations (AL-1) and (AL-2), R L1 and R L2 Each of these is independently a hydrocarbyl group having 1 to 40 carbon atoms, and 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. The hydrocarbyl group is preferably one having 1 to 20 carbon atoms.

[0135] In formula (AL-1), a2 is an integer between 0 and 10, preferably 1, 2, 3, 4, or 5.

[0136] In formula (AL-2), R L3 and R L4 Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, or fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Also, R L2 , R L3 and R L4 Any two of these may bond with each other to form a ring having 3 to 20 carbon atoms, together with the carbon atom to which they are bonded, or a carbon atom and an oxygen atom. The ring is preferably a ring having 4 to 16 carbon atoms, and an alicyclic ring is particularly preferred.

[0137] In formula (AL-3), R L5 , R L6 and R L7 Each of these is independently a hydrocarbyl group having 1 to 20 carbon atoms, and 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. Also, R L5 , RL6 and R L7 Any two of these may bond with each other to form a ring with 3 to 20 carbon atoms. The ring is preferably a ring with 4 to 16 carbon atoms, and an alicyclic ring is particularly preferred.

[0138] Other specific examples of the aforementioned acid-unstable groups include those described in paragraphs

[0064] to

[0068] of Japanese Patent Publication No. 2023-123222 and those described in paragraphs

[0013] to

[0014] of Japanese Patent Publication No. 7492842. These reactions are driven by the formation of conjugated olefins or acrylic acid ester derivatives after the acid elimination reaction.

[0139] Specific examples of repeating unit a1 are shown below, but are not limited to these. Note that in the following formula, R A and AL 1 This is the same as described above. [ka]

[0140] [ka]

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[0143] [ka]

[0144] Specific examples of repeating unit a2 are shown below, but are not limited to these. Note that in the following formula, R A and AL 2This is the same as described above. [ka]

[0145] [ka]

[0146] [ka]

[0147] The polymer may contain repeating units represented by the following formula (a3) ​​(hereinafter also referred to as repeating unit a3). [ka]

[0148] In formula (a3), a11 is either 0 or 1. When a11 is 0, it is a benzene ring, and when a11 is 1, it is a naphthalene ring, but from the viewpoint of solvent solubility, a11 being a benzene ring (a11 = 0) is preferred. When a11 is 0, a12 is 0, 1, 2, or 3, and when a11 is 1, it is 0, 1, 2, 3, 4, or 5. From the viewpoint of raw material procurement, a12 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2.

[0149] In formula (a3), R A This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Of these, it is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0150] In formula (a3), X 3 The bond is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. The asterisk (*) represents a bond with a carbon atom of the main chain. Of these, a single bond or *-C(=O)-O- is preferred, and a single bond is even more preferred.

[0151] In formula (a3), X 4 These are single bonds, aliphatic hydrocarbylene groups having 1 to 4 carbon atoms, carbonyl groups, sulfonyl groups, or groups obtained in combination thereof. Of these, single bonds, carbonyl groups, or sulfonyl groups are preferred from the viewpoint of raw material procurement, and single bonds or carbonyl groups are more preferred from the viewpoint of polar groups generated after the reaction.

[0152] In formula (a3), X 5 and X 6 Each of these is independently either an oxygen atom or a sulfur atom. However, X 4 and X 6 It is bonded to the carbon atom adjacent to the aromatic ring. 5 and X 6 They may be the same or different from each other, but from the standpoint of reactivity, X 5 and X 6 Preferably, both are oxygen atoms.

[0153] In formula (a3), R 12 and R 13Each of these is a C1-C20 hydrocarbyl group which may independently contain a hydrogen atom or a heteroatom. The hydrocarbyl 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; cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, and 4-methylcyclo Examples include cyclic saturated hydrocarbyl groups with 3 to 20 carbon atoms, such as hexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; alkenyl groups with 2 to 20 carbon atoms, such as vinyl, 1-propenyl, 2-propenyl, butenyl, and hexenyl groups; cyclic unsaturated hydrocarbyl groups with 3 to 20 carbon atoms, such as cyclohexenyl groups; aryl groups with 6 to 20 carbon atoms, such as phenyl and naphthyl groups; aralkyl groups with 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; 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.

[0154] Also, R 12 and R 13These may bond with each other to form a ring with the carbon atoms to which they are bonded. Specific examples of the ring formed in this case include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, an adamantane ring, and so on. Furthermore, some or all of the hydrogen atoms in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, the ring 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, 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)-), a haloalkyl group, and so on.

[0155] In formula (a3), R 14 This may include a halogen atom, a hydroxyl group, a cyano group, a nitro group, a C1-C20 hydrocarbyl group which may contain a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom, a C1-C20 hydrocarbylthio group which may contain a heteroatom, or -N(R 14A )(R 14B ) is R 14A and R 14B Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms. The halogen atom is preferably a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and more preferably a fluorine atom or an iodine atom. The hydrocarbyl portion of the hydrocarbyl group and the hydrocarbyloxy group, hydrocarbyloxycarbonyl group and hydrocarbylthio group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R 12 and R 13Examples of hydrocarbyl groups represented by the above are similar to those exemplified. 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, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether 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)-), a haloalkyl group, etc. When a12 is 2 or more, each R 14 They may be the same as or different from each other.

[0156] Also, when a12 is 2 or more, multiple R 14 However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded. Specific examples of the ring formed in this case include cyclopropane rings, cyclobutane rings, cyclopentane rings, cyclohexane rings, norbornane rings, adamantane rings, etc. Furthermore, some or all of the hydrogen atoms in the ring may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, halogen atoms, etc., and some of the -CH2- in the ring may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, etc., and as a result, the ring may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, 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.

[0157] Specific examples of repeating unit a3 are shown below, but are not limited to these. Note that in the following formula, R A The same as described above, where Me is a methyl group. Furthermore, the bonding positions of the various substituents on the aromatic ring may be interchanged. [ka]

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[0207] The base polymer may contain a repeating unit represented by the following formula (b1) (hereinafter also referred to as repeating unit b1) or a repeating unit represented by the following formula (b2) (hereinafter also referred to as repeating unit b2). [ka]

[0208] In equations (b1) and (b2), R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 The bond is either a single bond or *-C(=O)-O-. * represents a bond with a carbon atom in the main chain.21 R is a group having 1 to 20 carbon atoms that includes a hydrogen atom or at least one structure selected from a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride (-C(=O)-OC(=O)-). 22 This is a C1-C20 hydrocarbyl group which may contain a halogen atom, a carboxyl group, a nitro group, a cyano group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. When b2 is 2, 3, or 4, each R 22 b1 may be the same as b2, or it may be different from b2. b1 is 1, 2, 3, or 4. b2 is 0, 1, 2, 3, or 4, where 1 ≤ b1 + b2 ≤ 5.

[0209] Specific examples of repeating unit b1 are shown below, but are not limited to these. Note that in the following formula, R A This is the same as described above. [ka]

[0210] [ka]

[0211] [ka]

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[0225] Specific examples of repeating unit b2 are shown below, but are not limited to these. Note that in the following formula, R A This is the same as described above. [ka]

[0226] [ka]

[0227] [ka]

[0228] [ka]

[0229] [ka]

[0230] As for the repeating unit b1 or b2, in ArF lithography, it is particularly preferable to have a lactone ring as a polar group, and in KrF lithography, EB lithography, and EUV lithography, it is preferable to have a phenol moiety.

[0231] The base polymer may contain repeating units (hereinafter also referred to as repeating unit c) having a structure in which a hydroxyl group is protected by an acid-unstable group. The repeating unit c is not particularly limited as long as it has one or more structures in which a hydroxyl group is protected and the protecting group decomposes upon the action of an acid to generate a hydroxyl group, but it is preferably represented by the following formula (c1). [ka]

[0232] In formula (c1), R A R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 41 R is a (c+1) valent hydrocarbon group having 1 to 30 carbon atoms, which may contain heteroatoms. 42 c is an acid-unstable group. c is 1, 2, 3, or 4.

[0233] In formula (c1), R 42 The acid-unstable group represented by can be any group that is deprotected by the action of an acid and generates a hydroxyl group. 42 The structure is not particularly limited, but acetal structures, ketal structures, hydrocarbyloxycarbonyl groups, and hydrocarbyloxymethyl groups represented by the following formula (c2) are preferred, and the hydrocarbyloxymethyl group represented by the following formula (c2) is particularly preferred. [ka] (In the formula, * represents a bond. R 43 (This refers to a hydrocarbyl group with 1 to 15 carbon atoms.)

[0234] R 42 Specific examples of the acid-unstable group represented by formula (c2), the hydrocarbyloxymethyl group represented by formula (c2), and the repeating unit c are the same as those exemplified in the description of the repeating unit c described in Japanese Patent Application Publication No. 2020-111564.

[0235] The polymer may contain a repeating unit d derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or derivatives thereof. Specific examples of the monomer that gives the repeating unit d include, but are not limited to, those shown below.

Chemical formula

[0236] The polymer may contain a repeating unit e derived from indane, vinylpyridine, or vinylcarbazole.

[0237] In the polymer of the present invention, the content ratios of the repeating units A, a1, a2, a3, b1, b2, c, d, and e are preferably 0 < A ≤ 0.4, 0 ≤ a1 ≤ 0.8, 0 ≤ a2 ≤ 0.8, 0 ≤ a3 ≤ 0.6, 0 < a1 + a2 + a3 ≤ 0.8, 0 ≤ b1 ≤ 0.6, 0 ≤ b2 ≤ 0.6, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.3, and 0 ≤ e ≤ 0.3, and more preferably 0 < A ≤ 0.3, 0 ≤ a1 ≤ 0.7, 0 ≤ a2 ≤ 0.7, 0 ≤ a3 ≤ 0.5, 0 < a1 + a2 + a3 ≤ 0.7, 0 ≤ b1 ≤ 0.5, 0 ≤ b2 ≤ 0.5, 0 ≤ c ≤ 0.3, 0 ≤ d ≤ 0.3, and 0 ≤ e ≤ 0.3. However, A + a1 + a2 + a3 + b1 + b2 + c + d + e ≤ 1.0.

[0238] The weight average molecular weight (Mw) of the polymer is preferably 1000 to 500000, and more preferably 3000 to 100000. If Mw is within this range, sufficient etching resistance can be obtained, and there is no risk of deterioration of the resolution due to the inability to ensure the difference in dissolution rate before and after exposure. In the present invention, Mw is a polystyrene equivalent measurement value by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or N,N-dimethylformamide (DMF) as a solvent.

[0239] The molecular weight distribution (Mw / Mn) of the polymer tends to have a greater influence as the pattern rule becomes finer. Therefore, in order to obtain a resist composition suitable for fine pattern dimensions, it is preferable that the Mw / Mn is narrowly dispersed between 1.0 and 2.0. Within this range, there are few low molecular weight or high molecular weight polymers, and there is no risk of foreign matter being observed on the pattern or deterioration of the pattern shape after exposure.

[0240] One example of a method for synthesizing the aforementioned polymer is to heat a monomer that provides the repeating units described above in an organic solvent with a radical polymerization initiator added, and polymerize it.

[0241] Specific examples of organic solvents used during polymerization include toluene, benzene, THF, diethyl ether, dioxane, cyclohexane, cyclopentane, methyl ethyl ketone (MEK), propylene glycol monomethyl ether acetate (PGMEA), and γ-butyrolactone (GBL). Specific examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), 1,1'-azobis(1-acetoxy-1-phenylethane), 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 is preferably 50 to 150°C, and more preferably 60 to 100°C. The reaction time is preferably 2 to 24 hours, and more preferably 2 to 12 hours from the viewpoint of production efficiency.

[0242] The polymerization initiator may be added to the monomer solution and supplied to the reaction vessel, or an initiator solution may be prepared separately from the monomer solution and each supplied to the reaction vessel independently. Since the polymerization reaction may proceed and a superpolymer may be formed by radicals generated from the initiator during the waiting time, it is preferable from a quality control viewpoint to prepare the monomer solution and the initiator solution independently and add them dropwise. The acid-unstable group may be used as is, introduced into the monomer, or it may be protected or partially protected after polymerization. In addition, known chain transfer agents such as dodecyl mercaptan or 2-mercaptoethanol may be used in combination to adjust the molecular weight. In this case, the amount of these chain transfer agents added is preferably 0.01 to 20 mol% of the total amount of monomers to be polymerized.

[0243] In the case of monomers containing hydroxyl groups, the hydroxyl groups may be substituted with acetal groups that are easily deprotected by acids such as ethoxyethoxy groups during polymerization, and then deprotected with a weak acid and water after polymerization. Alternatively, they may be substituted with acetyl groups, formyl groups, pivaloyl groups, etc., and then alkaline hydrolysis may be performed after polymerization.

[0244] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, hydroxystyrene or hydroxyvinylnaphthalene may be polymerized by heating in an organic solvent with a radical polymerization initiator. Alternatively, acetoxystyrene or acetoxyvinylnaphthalene may be used, and after polymerization, the acetoxy group may be deprotected by alkaline hydrolysis to obtain polyhydroxystyrene or hydroxypolyvinylnaphthalene.

[0245] Specific examples of bases that can be used during alkaline hydrolysis include aqueous ammonia and triethylamine. The reaction temperature is preferably -20 to 100°C, more preferably 0 to 60°C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

[0246] The amount of each monomer in the monomer solution can be appropriately set, for example, to achieve a preferred content ratio of the repeating units described above.

[0247] The polymer obtained by the above manufacturing method may be treated as a final product if it is a reaction solution obtained by a polymerization reaction, or as a final product if it is a powder obtained by a purification process such as a reprecipitation method in which the polymerization solution is added to a poor solvent and a powder is obtained. However, from the viewpoint of work efficiency and quality stabilization, it is preferable to treat the polymer solution obtained by dissolving the powder obtained by the purification process in a solvent as the final product.

[0248] Specific examples of solvents used in this process include ketones such as cyclohexanone and methyl-2-n-pentyl ketone, as described in paragraphs

[0144] to

[0145] of Japanese Patent Publication No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether. Examples include ethers such as ethers; esters such as PGMEA, 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; lactones such as GBL; alcohols such as diacetone alcohol (DAA); high-boiling point alcoholic solvents such as diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, and 1,3-butanediol; and mixed solvents thereof.

[0249] In the polymer solution, the concentration of the polymer is preferably 0.01 to 30% by mass, and more preferably 0.1 to 20% by mass.

[0250] It is preferable to filter the reaction solution or polymer solution. Filtering removes foreign matter and gel that may cause defects, which is effective in stabilizing quality.

[0251] Examples of filter materials used in the aforementioned filter filtration include fluorocarbon, cellulose, nylon, polyester, and hydrocarbon materials. However, in the filtration process of the resist composition, filters made of fluorocarbon materials such as Teflon (registered trademark), hydrocarbon materials such as polyethylene and polypropylene, or nylon are preferred. The pore size of the filter can be appropriately selected according to the desired level of cleanliness, but is preferably 100 nm or less, and more preferably 20 nm or less. These filters may be used individually or in combination. The filtration method may involve passing the solution through only once, but it is more preferable to circulate the solution and filter it multiple times. The filtration process can be carried out in any order and number of times in the polymer manufacturing process, but it is preferable to filter the reaction solution after the polymerization reaction, the polymer solution, or both.

[0252] [Chemically Amplified Resist Composition] [(A) Base polymer] The chemically amplified resist composition of the present invention includes a base polymer containing the aforementioned polymer as component (A).

[0253] The aforementioned polymer may be used alone, or two or more polymers with different composition ratios, Mw, and / or Mw / Mn may be used in combination. In addition, the (A) base polymer may include hydrogenated ring-opening metathesis polymers in addition to the aforementioned polymers, and for this, those described in Japanese Patent Publication No. 2003-66612 may be used.

[0254] [(B) Organic solvents] The chemically amplified resist composition of the present invention may contain an organic solvent as component (B). The organic solvent (B) is not particularly limited as long as it is capable of dissolving the components described above and the components described later. Specific examples of such organic solvents include ketones such as cyclopentanone, cyclohexanone, and methyl-2-n-pentyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; keto alcohols such as DAA; ethers such as PGME, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as PGMEA, 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; lactones such as GBL; and mixed solvents of these.

[0255] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, cyclohexanone, GBL, ethyl lactate, DAA, and mixed solvents thereof are preferred, as they exhibit particularly excellent solubility of the base polymer of component (A).

[0256] In the chemically amplified resist composition of the present invention, the content of (B) organic solvent is preferably 200 to 7000 parts by mass, and more preferably 400 to 5000 parts by mass, per 80 parts by mass of (A) base polymer. (B) organic solvent may be used alone or as a mixture of two or more types.

[0257] [(C) Quencher] The chemically amplified resist composition of the present invention may contain a quencher as component (C). In this invention, a quencher is a material that traps the acid generated from the photoacid generator in the chemically amplified resist composition, thereby preventing its diffusion to unexposed areas and forming a desired pattern.

[0258] (C)Specific examples of quenchers include onium salts represented by the following formulas (1) or (2). [ka]

[0259] In formula (1), R q1 This is a C1-C40 hydrocarbyl group which may contain a hydrogen atom or a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group. In formula (2), R q2 This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a hydrogen atom or a heteroatom.

[0260] R q1 Specifically, the C1-C40 hydrocarbyl groups represented by include C1-C40 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6Examples include cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as decyl groups and adamantyl groups; and aryl groups having 6 to 40 carbon atoms, such as phenyl groups, naphthyl groups, and anthracenyl groups. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. As a result, the group may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, 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.

[0261] R q2 Specifically, the hydrocarbyl group represented by R q1 In addition to the substituents exemplified as specific examples, other examples include fluorinated saturated hydrocarbyl groups such as trifluoromethyl and trifluoroethyl groups, and fluorinated aryl groups such as pentafluorophenyl and 4-trifluoromethylphenyl groups.

[0262] Specific examples of anions of onium salts represented by formula (1) are listed below, but are not limited to these. [ka]

[0263] [ka]

[0264] [ka]

[0265] [ka]

[0266] [ka]

[0267] Specific examples of anions of onium salts represented by formula (2) are listed below, but are not limited to these. [ka]

[0268] [ka]

[0269] [ka]

[0270] [ka]

[0271] [ka]

[0272] In equations (1) and (2), MQ + This is an onium cation. Examples of the onium cation include sulfonium cations, iodonium cations, ammonium cations, etc. Specific examples of the sulfonium cation include those exemplified as specific examples of sulfonium cations represented by formula (Z-1) and sulfonium cations represented by formula (Z-3), those described in paragraphs

[0102] to

[0125] of Japanese Patent Application Publication No. 2024-3744, those described in paragraphs

[0044] to

[0049] of International Publication No. 2024 / 128017, and those described in paragraphs

[0035] to

[0046] of Japanese Patent No. 7491173, but are not limited to these.

[0273] Specific examples of the iodonium cation mentioned above include, but are not limited to, those described in paragraph

[0181] of Japanese Patent Publication No. 2024-259.

[0274] A specific example of the ammonium cation is the one represented by the following formula (am-1). [ka] In formula (am-1), R q11 ~R q14 Each of these is independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain heteroatoms. Also, R q11 and R q12 However, they may bond with each other to form a ring with the nitrogen atom to which they are bonded. A specific example of the hydrocarbyl group is R in the explanation of formula (A). 1 Examples of hydrocarbyl groups represented by the same formula as those exemplified above include those shown.

[0275] Specific examples of ammonium cations represented by formula (am-1) are listed below, but are not limited to these. [ka]

[0276] Specific examples of onium salts represented by formula (1) or (2) include any combination of the anions and cations mentioned above. These onium salts can be easily prepared by ion exchange reactions using known organic chemical methods. For ion exchange reactions, refer to, for example, Japanese Patent Publication No. 2007-145797.

[0277] The onium salt represented by formula (1) or (2) acts as a quencher in the chemically amplified resist composition of the present invention. This is because each counteranion of the onium salt is a conjugate base of a weak acid. Here, a weak acid refers to an acidity that does not deprotect the acid-unstable groups of the acid-unstable group-containing units used in the base polymer. The onium salt represented by formula (1) or (2) functions as a quencher when used in combination with an onium salt type photoacid generator having a conjugate base of a strong acid, such as a sulfonic acid with fluorinated α-position, as a counteranion. That is, when an onium salt that generates a strong acid, such as a sulfonic acid with fluorinated α-position, is mixed with an onium salt that generates a weak acid, such as an unfluorinated sulfonic acid or carboxylic acid, when the strong acid generated from the photoacid generator by high-energy ray irradiation collides with the onium salt having an unreacted weak acid anion, the weak acid is released by salt exchange, and an onium salt having a strong acid anion is produced. In this process, strong acids are replaced by weaker acids with lower catalytic activity, so the acids appear to be deactivated, allowing for control of acid diffusion.

[0278] Furthermore, as the (C) 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, and 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.

[0279] Here, if the photoacid generator that produces a strong acid is an onium salt, as mentioned above, the strong acid produced by high-energy ray irradiation can be exchanged for a weak acid. On the other hand, it is thought that the weak acid produced by high-energy ray irradiation is unlikely to collide with the unreacted onium salt that produces the strong acid and undergo salt exchange. This is due to the phenomenon that onium cations are more likely to form ion pairs with the anions of stronger acids.

[0280] When the chemically amplified resist composition of the present invention contains an onium salt represented by formula (1) or (2) as the (C) quencher, its content is preferably 0.1 to 20 parts by mass, and more preferably 0.1 to 10 parts by mass, per 80 parts by mass of the (A) base polymer. When the content of the onium salt type quencher of component (C) is within the above range, the resolution is good and the sensitivity does not decrease significantly, which is preferable. The onium salt represented by formula (1) or (2) may be used alone or in combination of two or more types.

[0281] The chemically amplified resist composition of the present invention may contain a nitrogen-containing compound as the (C) quencher. Specific examples of nitrogen-containing compounds of component (C) include primary, secondary, or tertiary amine compounds described in paragraphs

[0146] to

[0164] of Japanese Patent Application Publication No. 2008-111103, particularly amine compounds having a hydroxyl group, ether bond, ester bond, lactone ring, cyano group, or sulfonic acid ester bond. Compounds of primary or secondary amines protected with a carbamate group, as described in Japanese Patent Application Publication No. 3790649, can also be cited.

[0282] Furthermore, a sulfonium sulfonate salt having a nitrogen-containing substituent may be used as the nitrogen-containing compound. Such a compound functions as a quencher in the unexposed area and loses its quenching ability in the exposed area through neutralization with its own generated acid, functioning as a so-called photodecayable base. By using a photodecayable base, the contrast between the exposed and unexposed areas can be further enhanced. For example, Japanese Patent Publication No. 2009-109595 and Japanese Patent Publication No. 2012-46501 can be referenced as examples of photodecayable bases.

[0283] When the chemically amplified resist composition of the present invention contains a nitrogen-containing compound as (C) quencher, the 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 (A) base polymer. The nitrogen-containing compound may be used alone or in combination of two or more types.

[0284] [(D) Photoacid Generator] The chemically amplified resist composition of the present invention may contain a photoacid generator as component (D). The photoacid generator is not particularly limited as long as it is a compound that generates acid upon irradiation with high-energy rays. Suitable photoacid generators include those represented by the following formulas (3) or (4). [ka]

[0285] In formula (3), R 101 ~R 105 Each of these is independently a C1-C20 hydrocarbyl group which may contain a halogen atom or a heteroatom. 101 , R 102 and R 103 Any two of these may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0286] Specific examples of sulfonium salt cations represented by formula (3) include those exemplified as specific examples of sulfonium cations represented by formula (Z-1) and sulfonium cations represented by formula (Z-3), those described in paragraphs

[0102] to

[0125] of Japanese Patent Application Publication No. 2024-3744, those described in paragraphs

[0044] to

[0049] of International Publication No. 2024 / 128017, and those described in paragraphs

[0035] to

[0046] of Japanese Patent No. 7491173, but are not limited to these. Specific examples of iodonium salt cations represented by formula (4) include those described in paragraph

[0181] of Japanese Patent Application Publication No. 2024-259, but are not limited to these.

[0287] In equations (3) and (4), Xa - This is an anion of a strong acid. Examples of the strong acid anions include those represented by any of the following formulas (Xa-1) to (Xa-4). [ka]

[0288] In equation (Xa-1), Rfa R is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (Xa-1-1) described later. fa1 Examples of hydrocarbyl groups represented by the symbol shown are similar to those exemplified.

[0289] The anion represented by formula (Xa-1) is preferably the one represented by the following formula (Xa-1-1). [ka]

[0290] In equation (Xa-1-1), Q 1 and Q 2 Each of these is independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, but to improve solvent solubility, it is preferable that at least one of them is a trifluoromethyl group. m is 0, 1, 2, 3, or 4, but it is particularly preferable that it is 1. R fa1 This is a hydrocarbyl group having 1 to 35 carbon atoms, which may contain heteroatoms. The heteroatoms are preferably oxygen atoms, nitrogen atoms, sulfur atoms, halogen atoms, etc., with oxygen atoms being more preferred. From the viewpoint of obtaining high resolution in fine pattern formation, the hydrocarbyl group having 6 to 30 carbon atoms is particularly preferred.

[0291] In equation (Xa-1-1), R fa1The C1-C35 hydrocarbyl group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include C1-C35 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, 2-ethylhexyl, nonyl, undecyl, tridecyl, pentadecyl, heptadecyl, and eicosyl; cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, 1-adamantylmethyl, norbornyl, norbornyl Examples include cyclic saturated hydrocarbyl groups with 3 to 35 carbon atoms, such as nylmethyl, tricyclodecyl, tetracyclododecyl, tetracyclododecylmethyl, and dicyclohexylmethyl; unsaturated aliphatic hydrocarbyl groups with 2 to 35 carbon atoms, such as 2-propenyl and 3-cyclohexenyl; aryl groups with 6 to 35 carbon atoms, such as phenyl, 1-naphthyl, 2-naphthyl, and 9-fluorenyl; aralkyl groups with 7 to 35 carbon atoms, such as benzyl and diphenylmethyl; and groups obtained by combining these.

[0292] 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 nitro group, a carbonyl group, an ether 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)-), a haloalkyl group, etc. Specific examples of hydrocarbyl groups containing heteroatoms include tetrahydrofuryl group, methoxymethyl group, ethoxymethyl group, methylthiomethyl group, acetamidomethyl group, trifluoroethyl group, (2-methoxyethoxy)methyl group, acetoxymethyl group, 2-carboxy-1-cyclohexyl group, 2-oxopropyl group, 4-oxo-1-adamantyl group, and 3-oxocyclohexyl group.

[0293] In equation (Xa-1-1), L a1 The bond can be a single bond, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, or a carbamate bond, but from a synthetic viewpoint, an ether bond or an ester bond is preferred, and an ester bond is even more preferred.

[0294] Specific examples of anions represented by formula (Xa-1) are listed below, but are not limited to these. Note that in the formula below, Q 1 This is the same as above, and Ac is an acetyl group. [ka]

[0295] [ka]

[0296] [ka]

[0297] [ka]

[0298] [ka]

[0299] [ka]

[0300] [ka]

[0301] [ka]

[0302] [ka]

[0303] [ka]

[0304] [ka]

[0305] [ka]

[0306] In equation (Xa-2), R fb1 and R fb2 Each of these is a hydrocarbyl group having 1 to 40 carbon atoms, which may independently contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (Xa-1-1). fa1 Examples of hydrocarbyl groups represented by R include those similar to those exemplified. fb1 and R fb2 Preferably, R is a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 However, they bond to each other and the group to which they bond (-CF2-SO2-N - It may form a ring with -SO2-CF2-), in which case R fb1 and R fb2 The groups obtained by the bonding of these groups are preferably fluorinated ethylene groups or fluorinated propylene groups.

[0307] In equation (Xa-3), R fc1 , R fc2 and R fc3Each of these is a hydrocarbyl group having 1 to 40 carbon atoms, which may independently contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (Xa-1-1). fa1 Examples of hydrocarbyl groups represented by R include those similar to those exemplified. fc1 , R fc2 and R fc3 Preferably, R is a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 However, they bond to each other and the group to which they bond (-CF2-SO2-C - It may form a ring with -SO2-CF2-), in which case R fc1 and R fc2 The groups obtained by the bonding of these groups are preferably fluorinated ethylene groups or fluorinated propylene groups.

[0308] In equation (Xa-4), R fd R is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain heteroatoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (Xa-1-1). fa1 Examples of hydrocarbyl groups represented by the same formula as those exemplified above include those shown.

[0309] Specific examples of anions represented by formula (Xa-4) are listed below, but are not limited to these. [ka]

[0310] [ka]

[0311] Further examples of the aforementioned non-nucleophilic counterions include anions having an aromatic ring substituted with an iodine or bromine atom. A specific example of such anion is represented by the following formula (Xa-5). [ka]

[0312] In equation (Xa-5), x is 1, 2, or 3. y is 1, 2, 3, 4, or 5. z is 0, 1, 2, or 3, where 1 ≤ y + z ≤ 5. y is preferably 1, 2, or 3, more preferably 2 or 3. z is preferably 0, 1, or 2.

[0313] In equation (Xa-5), X BI is an iodine atom or a bromine atom. When x and / or y are 2 or more, each X BI They may be the same as or different from each other.

[0314] In equation (Xa-5), L 1 This is a saturated hydrocarbylene group having 1 to 6 carbon atoms, which may contain a single bond, an ether bond, or an ester bond, or an ether bond or an ester bond. The saturated hydrocarbylene group may be linear, branched, or cyclic.

[0315] In equation (Xa-5), L 2 When x is 1, it is a single bond or a divalent linking group having 1 to 20 carbon atoms, and when x is 2 or 3, it is a (x+1) valent linking group having 1 to 20 carbon atoms, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0316] In equation (Xa-5), R feThis may include a hydroxyl group, a carboxyl group, a fluorine atom, a chlorine atom, a bromine atom, or an amino group, or a fluorine atom, a chlorine atom, a bromine atom, a hydroxyl group, an amino group, or an ether bond, and may contain a C1-C20 hydrocarbyl group, a C1-C20 hydrocarbyloxy group, a C2-C20 hydrocarbylcarbonyl group, a C2-C20 hydrocarbyloxycarbonyl group, a C2-C20 hydrocarbylcarbonyloxy group, or a C1-C20 hydrocarbylsulfonyloxy group, or -N(R feA )(R feB ), -N(R feC )-C(=O)-R feD Or -N(R feC )-C(=O)-OR feD That is. R feA and R feB Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. feC R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may also contain a halogen atom, a hydroxyl group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. feD This is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may contain a halogen atom, a hydroxyl group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. The aliphatic hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group, hydrocarbyloxy group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, and hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When x and / or z is 2 or more, each R fe They may be the same as or different from each other.

[0317] Of these, R feExamples include hydroxyl groups, -N(R feC )-C(=O)-R feD , -N(R feC )-C(=O)-OR feD Fluorine atoms, chlorine atoms, bromine atoms, methyl groups, methoxy groups, etc. are preferred.

[0318] In formula (Xa-5), Rf 11 ~Rf 14 Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one of these is either a fluorine atom or a trifluoromethyl group. Also, Rf 11 and Rf 12 These may combine to form a carbonyl group. In particular, Rf 13 and Rf 14 It is preferable that both are fluorine atoms.

[0319] Specific examples of anions represented by formula (Xa-5) are listed below, but are not limited to these. Note that in the following formula, X BI This is the same as described above. [ka]

[0320] [ka]

[0321] [ka]

[0322] [ka]

[0323] [ka]

[0324]

change

[0325]

change

[0326]

change

[0327]

change

[0328]

change

[0329]

change

[0330]

change

[0331]

change

[0332]

change

[0333]

change

[0334]

change

[0335]

change

[0336]

change

[0337]

change

[0338]

change

[0339]

change

[0340]

change

[0341]

change

[0342]

change

[0343] As the non-nucleophilic counterions, the following can also be used: a fluorobenzenesulfonic acid anion bonded to an aromatic group containing an iodine atom, as described in Japanese Patent No. 6648726; an anion having a mechanism for decomposition by acid, as described in International Publication No. 2021 / 200056 and Japanese Patent Application Publication No. 2021-70692; an anion having a cyclic ether group, as described in Japanese Patent Application Publication No. 2018-180525 and Japanese Patent Application Publication No. 2021-35935; and an anion described in Japanese Patent Application Publication No. 2018-92159.

[0344] As the non-nucleophilic counterions, anions of bulky benzenesulfonic acid derivatives that do not contain fluorine atoms, as described in Japanese Patent Publication No. 2006-276759, Japanese Patent Publication No. 2015-117200, Japanese Patent Publication No. 2016-65016, and Japanese Patent Publication No. 2019-202974, as well as benzenesulfonic acid anions or alkylsulfonic acid anions that do not contain fluorine atoms bonded to an aromatic group containing an iodine atom, as described in Japanese Patent No. 6645464.

[0345] As the non-nucleophilic counterion, other options include the bissulfonic acid anion described in Japanese Patent Publication No. 2015-206932, the sulfonamide or sulfonimide anion described in International Publication No. 2020 / 158366, which has a sulfonic acid on one end and a different sulfonamide or sulfonimide on the other, and the sulfonate anion described in Japanese Patent Publication No. 2015-24989.

[0346] Furthermore, as the photoacid generator for component (D), one represented by the following formula (5) is also preferred. [ka]

[0347] In formula (5), R 201 and R 202 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain heteroatoms. 203 This is a hydrocarbylene group having 1 to 30 carbon atoms, which may contain heteroatoms. Also, R201 , R 202 and R 203 Any two of these may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0348] R 201 and R 202 The C1-C30 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, 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, oxanorbornyl, and tricyclo[5.2.1.0 2,6Examples include cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as decyl groups and adamantyl groups; aryl groups having 6 to 30 carbon atoms, such as phenyl groups, methylphenyl groups, ethylphenyl groups, n-propylphenyl groups, isopropylphenyl groups, n-butylphenyl groups, isobutylphenyl groups, sec-butylphenyl groups, tert-butylphenyl groups, naphthyl groups, methylnaphthyl groups, ethylnaphthyl groups, n-propylnaphthyl groups, isopropylnaphthyl groups, n-butylnaphthyl groups, isobutylnaphthyl groups, sec-butylnaphthyl groups, tert-butylnaphthyl groups, anthracenyl groups, 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.

[0349] R 203The hydrocarbylene group, represented by , having 1 to 30 carbon atoms, may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkane diyl groups with 1 to 30 carbon atoms, such as methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group, etc.; cyclop Examples include cyclic saturated hydrocarbylene groups having 3 to 30 carbon atoms, such as tananediyl group, cyclohexanediyl group, norbornanediyl group, and adamantanediyl group; and arylene groups such as phenylene group, methylphenylene group, ethylphenylene group, n-propylphenylene group, isopropylphenylene group, n-butylphenylene group, isobutylphenylene group, sec-butylphenylene group, tert-butylphenylene group, naphthylene group, methylnaphthylene group, ethylnaphthylene group, n-propylnaphthylene group, isopropylnaphthylene group, n-butylnaphthylene group, isobutylnaphthylene group, sec-butylnaphthylene group, and tert-butylnaphthylene group. Furthermore, some or all of the hydrogen atoms of the hydrocarbylene 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 hydrocarbylene 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 cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether 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)-), a haloalkyl group, etc. The heteroatom is preferably an oxygen atom.

[0350] In formula (5), L 11This is a 1-20 carbon atom hydrocarbylene group which may contain single bonds, ether bonds, or heteroatoms. The hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R 203 Examples of hydrocarbylene groups represented by the same formula as those exemplified above include the same groups as those shown.

[0351] In formula (5), X a , X b , X c and X d Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group. However, X a , X b , X c and X d At least one of these is a fluorine atom or a trifluoromethyl group.

[0352] The photoacid generator represented by formula (5) is preferably the one represented by the following formula (5'). [ka]

[0353] In formula (5'), L 11 This is the same as above. X e R is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. 301 , R 302 and R 303 Each of these is a hydrocarbyl group having 1 to 20 carbon atoms, which may each contain a hydrogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (Xa-1-1). fa1 Examples of hydrocarbyl groups represented by the formula are similar to those exemplified. s and t are independently 0, 1, 2, 3, 4, or 5, and u is 0, 1, 2, 3, or 4.

[0354] Specific examples of the photoacid generator represented by formula (5) include those similar to those exemplified as the photoacid generator represented by formula (2) in Japanese Patent Publication No. 2017-26980.

[0355] Among the photoacid generators, those containing an anion represented by formula (Xa-1-1) or (Xa-4) are particularly preferred because they exhibit low acid diffusion and excellent solubility in solvents. Furthermore, those represented by formula (5') are particularly preferred because they exhibit extremely low acid diffusion.

[0356] If the chemically amplified resist composition of the present invention contains (D) a photoacid generator, its content is preferably 0.1 to 40 parts by mass, and more preferably 0.5 to 20 parts by mass, per 80 parts by mass of the (A) base polymer. When the amount of (D) photoacid generator added is within the above range, the resolution is good and there is no risk of foreign matter problems occurring after development or peeling of the resist film, so it is preferable. (D) The photoacid generator may be used alone or in combination of two or more types.

[0357] [(E) Surfactants] The chemically amplified resist composition of the present invention may further contain a surfactant as component (E). Preferably, the surfactant (E) is a surfactant that is insoluble or sparingly soluble in water and soluble in an alkaline developer, or a surfactant that is insoluble or sparingly soluble in both water and an alkaline developer. Examples of such surfactants can be found in Japanese Patent Publication No. 2010-215608 and Japanese Patent Publication No. 2011-16746.

[0358] As surfactants that are insoluble or poorly soluble in water and alkaline developer, among the surfactants described in the above publication, FC-4430 (manufactured by 3M), Surflon® S-381 (manufactured by AGC Seimi Chemical Co., Ltd.), Orfin® E1004 (manufactured by Nisshin Chemical Industry Co., Ltd.), KH-20, KH-30 (manufactured by AGC Seimi Chemical Co., Ltd.), and oxetane ring-opening polymers represented by the following formula (surf-1) are preferred. [ka]

[0359] Here, R, Rf, A, B, C, m, and n apply only to formula (surf-1), notwithstanding the preceding description. R is a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Examples of such aliphatic groups include the divalent ethylene group, 1,4-butylene group, 1,2-propylene group, 2,2-dimethyl-1,3-propylene group, and 1,5-pentylene group, while examples of trivalent or tetravalent aliphatic groups are listed below. [ka] (In the formula, the dashed lines represent bonds, which are substructures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.)

[0360] Among these, the 1,4-butylene group and the 2,2-dimethyl-1,3-propylene group are preferred.

[0361] Rf is a trifluoromethyl group or a pentafluoroethyl group, preferably a trifluoromethyl group. m is an integer from 0 to 3, n is an integer from 1 to 4, and the sum of n and m is the valence of R, an integer from 2 to 4. A is 1. B is an integer from 2 to 25, preferably an integer from 4 to 20. C is an integer from 0 to 10, preferably 0 or 1. Furthermore, the order of each constituent unit in formula (surf-1) is not specified, and they may be bonded in a block-like manner or randomly. For details on the production of partially fluorinated oxetane ring-opening polymer surfactants, please refer to U.S. Patent No. 5,650,483, etc.

[0362] Surfactants that are insoluble or sparingly soluble in water and soluble in alkaline developers have the function of reducing water penetration and leaching by orienting themselves on the surface of the resist film when a resist protective film is not used in ArF immersion lithography. Therefore, they are useful in suppressing the elution of water-soluble components from the resist film and reducing damage to the exposure equipment. Furthermore, they are useful because they become solubilized during alkaline aqueous solution development after exposure or post-exposure bake (PEB) and are less likely to become foreign substances that cause defects. Such surfactants are insoluble or sparingly soluble in water and soluble in alkaline developers, and are polymer-type surfactants, also called hydrophobic resins, with those that have particularly high water repellency and improve water lubricity being preferred.

[0363] Specific examples of such polymer-type surfactants include those containing at least one repeating unit selected from any of the following formulas (6A) to (6E). [ka]

[0364] In formulas (6A) to (6E), R B is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 R is -CH2-, -CH2CH2-, -O-, or two separated -H atoms. s1 Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. s2 R is a single bond or a linear or branched hydrocarbylene group having 1 to 5 carbon atoms. s3 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group or a fluorinated hydrocarbyl group, or an acid-unstable group. s3 If the group is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds. s4 R is a (w+1) valent hydrocarbon group or fluorinated hydrocarbon group having 1 to 20 carbon atoms. w is 1, 2, or 3. s5 These are, independently, hydrogen atoms, or -C(=O)-ORsa It is a group represented by R. sa This is a fluorinated hydrocarbyl group having 1 to 20 carbon atoms. s6 This is a hydrocarbyl group having 1 to 15 carbon atoms or a fluorinated hydrocarbyl group, and an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds.

[0365] R s1 The C1-C10 hydrocarbyl group represented by is preferably a saturated hydrocarbyl group and may be linear, branched, or cyclic. Specific examples include C1-C10 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl groups; and C3-C10 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl groups. Of these, those with C1-C6 are preferred.

[0366] R s2 The hydrocarbylene group represented by is preferably a saturated hydrocarbylene group and may be linear, branched, or cyclic. Specific examples include methylene, ethylene, propylene, butylene, and pentylene groups.

[0367] R s3 or R s6 The hydrocarbyl group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include saturated hydrocarbyl groups, alkenyl groups, alkynyl groups, and other aliphatic unsaturated hydrocarbyl groups, but saturated hydrocarbyl groups are preferred. A specific example of the saturated hydrocarbyl group is R s1 In addition to the examples given as hydrocarbyl groups represented by , other examples include undecyl groups, dodecyl groups, tridecyl groups, tetradecyl groups, pentadecyl groups, etc. s3 or R s6Examples of fluorinated hydrocarbyl groups represented by the above-mentioned hydrocarbyl group include groups in which some or all of the hydrogen atoms bonded to the carbon atoms are replaced with fluorine atoms. As mentioned above, ether bonds or carbonyl groups may be interposed between these carbon-carbon bonds.

[0368] R s3 Specific examples of acid-unstable groups represented by the formulas (AL-3) to (AL-5) mentioned above include trialkylsilyl groups in which each alkyl group has 1 to 6 carbon atoms, and alkyl groups containing oxo groups with 4 to 20 carbon atoms.

[0369] R s4 The (w+1) valent hydrocarbon group or fluorinated hydrocarbon group represented by can be linear, branched, or cyclic. Specific examples include groups obtained by further removing w hydrogen atoms from the aforementioned hydrocarbyl group or fluorinated hydrocarbyl group.

[0370] R sa The fluorinated hydrocarbyl group represented by is preferably saturated and may be linear, branched, or cyclic. Specific examples include those in which some or all of the hydrogen atoms of the hydrocarbyl group are substituted with fluorine atoms, and specific examples of such include trifluoromethyl group, 2,2,2-trifluoroethyl group, 3,3,3-trifluoro-1-propyl group, 3,3,3-trifluoro-2-propyl group, 2,2,3,3-tetrafluoropropyl group, 1,1,1,3,3,3-hexafluoroisopropyl group, 2,2,3,3,4,4,4-heptafluorobutyl group, 2,2,3,3,4,4,5,5-octafluoropentyl group, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl group, 2-(perfluorobutyl)ethyl group, 2-(perfluorohexyl)ethyl group, 2-(perfluorooctyl)ethyl group, 2-(perfluorodecyl)ethyl group, etc.

[0371] Specific examples of repeating units represented by any of the formulas (6A) to (6E) are shown below, but are not limited to these. Note that in the formulas below, R B This is the same as described above. [ka]

[0372] [ka]

[0373] [ka]

[0374] [ka]

[0375] [ka]

[0376] [ka]

[0377] The polymer-type surfactant may further contain other repeating units other than those represented by formulas (6A) to (6E). Specific examples of other repeating units include those obtained from methacrylic acid and α-trifluoromethylacrylic acid derivatives. In the polymer-type surfactant, the content of the repeating units represented by formulas (6A) to (6E) is preferably 20 mol% or more, more preferably 60 mol% or more, and even more preferably 100 mol% of the total repeating units.

[0378] The Mw of the polymer-type surfactant is preferably 1,000 to 500,000, and more preferably 3,000 to 100,000. The Mw / Mn ratio is preferably 1.0 to 2.0, and more preferably 1.0 to 1.6.

[0379] A method for synthesizing the polymer-type surfactant involves polymerizing a monomer containing unsaturated bonds that give repeating units represented by formulas (6A) to (6E), and optionally other repeating units, by heating it in an organic solvent with a radical initiator. Specific examples of organic solvents used during polymerization include toluene, benzene, THF, diethyl ether, and dioxane. Specific 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 is preferably 50 to 100°C. 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.

[0380] When synthesizing the polymer-type surfactant, known chain transfer agents such as dodecyl mercaptan or 2-mercaptoethanol may be used to adjust the molecular weight. In that case, the amount of these chain transfer agents added is preferably 0.01 to 10 mol% relative to the total number of moles of monomers to be polymerized.

[0381] If the chemically amplified resist composition of the present invention contains (E) a surfactant, its content is preferably 0.1 to 50 parts by mass, and more preferably 0.5 to 10 parts by mass, per 80 parts by mass of the (A) base polymer. If the content of (E) surfactant is 0.1 parts by mass or more, the receding contact angle between the resist film surface and water is sufficiently improved, and if it is 50 parts by mass or less, the dissolution rate of the resist film surface in the developer is small, and the height of the formed fine pattern is sufficiently maintained. (E) surfactant may be used alone or in combination of two or more types.

[0382] [(F) Other ingredients] The chemically amplified resist composition of the present invention may also contain, as (F) other components, compounds that decompose with acid to generate acid (acid-proliferating compounds), organic acid derivatives, fluorine-substituted alcohols, compounds with an Mw of 3000 or less whose solubility in the developer changes due to the action of acid (dissolution inhibitors), etc. As the acid-proliferating compounds, compounds described in Japanese Patent Publication No. 2009-269953 or Japanese Patent Publication No. 2010-215608 can be referenced. When the acid-proliferating compounds are included, their content is preferably 0 to 5 parts by mass, and more preferably 0 to 3 parts by mass, per 80 parts by mass of the (A) base polymer. If the content is too high, it becomes difficult to control acid diffusion, which may lead to deterioration of resolution and pattern shape. As the organic acid derivatives, fluorine-substituted alcohols and dissolution inhibitors, compounds described in Japanese Patent Publication No. 2009-269953 or Japanese Patent Publication No. 2010-215608 can be referenced.

[0383] [Pattern formation method] The pattern formation method of the present invention includes the steps of forming a resist film on a substrate using the chemically amplified resist composition described above, exposing the resist film with high-energy rays, and developing the exposed resist film using a developer.

[0384] As the substrate, for example, substrates for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coatings, etc.) or substrates for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.) can be used.

[0385] The resist film can be formed by, for example, applying the chemically amplified resist composition onto a substrate using a method such as spin coating to a film thickness of preferably 0.05 to 2 μm, and then pre-baking it on a hot plate at preferably 60 to 150°C for 1 to 10 minutes, more preferably 80 to 140°C for 1 to 5 minutes.

[0386] High-energy beams used for exposure of resist films include KrF excimer laser light, ArF excimer laser light, EB, and EUV with wavelengths of 3 to 15 nm. When using KrF excimer laser light, ArF excimer laser light, or EUV, exposure is performed using a mask to form the desired pattern, with an exposure dose of preferably 1 to 200 mJ / cm². 2 More preferably 10-100 mJ / cm² 2 This can be done by irradiating in such a manner. When using EB, the exposure amount is preferably 1 to 300 μC / cm², either using a mask to form the desired pattern or directly. 2 More preferably 10-200 μC / cm 2 Irradiate in such a way that it results in the following.

[0387] In addition to conventional exposure methods, immersion methods can also be used, in which a liquid with a refractive index of 1.0 or higher is interposed between the resist film and the projection lens. In this case, a protective film insoluble in water can also be used.

[0388] 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.

[0389] PEB may be performed after exposure. PEB can be performed, for example, by heating on a hot plate, preferably at 60-150°C for 1-5 minutes, more preferably at 80-140°C for 1-3 minutes.

[0390] Development is carried out using a developer solution, preferably an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH) in an amount of 0.1 to 5% by mass, more preferably 2 to 3% by mass, and by conventional methods such as the dip method, puddle method, or spray method for preferably 0.1 to 3 minutes, more preferably 0.5 to 2 minutes, which dissolves the exposed areas and forms the desired pattern on the substrate.

[0391] Furthermore, after the resist film is formed, a rinse with pure water may be performed to extract acid generators or other substances from the film surface, or to wash away particles. Alternatively, a rinse may be performed after exposure to remove any water remaining on the film.

[0392] Furthermore, patterns may be formed by a double patterning method. Examples of double patterning methods include the trench method, in which a 1:3 trench pattern base is processed with the first exposure and etching, and then a 1:3 trench pattern is formed by a second exposure with a shifted position to form a 1:1 pattern; and the line method, in which a first base for a 1:3 isolated pattern is processed with the first exposure and etching, and then a second exposure with a shifted position to process a second base formed beneath the first base for a 1:3 isolated pattern to form a 1:1 pattern with half the pitch.

[0393] In the pattern formation method of the present invention, a negative tone development method may be used in which an organic solvent is used as the developer to dissolve the unexposed areas instead of the alkaline aqueous solution.

[0394] For the aforementioned organic solvent development, the developer may be 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, ethyl crotate, propyl acetate, methyl propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotate, ethyl crotate, propyl propyl acetate, methyl propyl formate, methyl pentenoate, methyl crotate, ethyl crotate, propyl propyl acetate, methyl propyl formate, methyl pentenoate, methyl crotate, ethyl crotate, propyl propyl acetate, methyl propyl formate, methyl pentenoate, methyl crotate, methyl propyl acetate, methyl propyl formate, methyl propyl formate, methyl pentenoate, methyl crotate, methyl propyl acetate, methyl propyl formate, methyl propyl acetate, methyl pentenoate, methyl crotate, methyl propyl acetate, methyl propyl acetate, methyl pentenoate, methyl crotate, methyl propyl acetate, methyl propyl acetate, methyl pentenoate, methyl methyl crotate, methyl propyl acetate, methyl propyl acetate, methyl pentenoate, methyl methyl crotate, methyl propyl acetate, methyl propyl acetate, methyl propyl acetate, methyl pentenoate, methyl Methyl ropionate, 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, ethyl phenyl acetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, 2-phenylethyl acetate, etc. can be used. These organic solvents may be used individually or in mixtures of two or more. [Examples]

[0395] The present invention will be specifically described below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. The apparatus used is as follows. • MALDI TOF-MS: S3000 manufactured by JEOL Ltd.

[0396] [1] Synthesis of onium salt type monomers [Example 1-1] Synthesis of onium salt type monomer a-1 [ka]

[0397] (1) Synthesis of intermediate In-1 Under a nitrogen atmosphere, starting materials SM-1 (19.6g), SM-2 (41.5g), 4-dimethylaminopyridine (1.2g), and methylene chloride (200g) were added to a reaction vessel and cooled in an ice bath. While maintaining the temperature inside the reaction vessel below 20°C, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (23.0g) was added in powder form. After addition, the temperature was raised to room temperature and aged for 12 hours. After aging, water (100g) was added to stop the reaction, and a normal aqueous work-up was performed. After removing the solvent by distillation, diisopropyl ether was added and recrystallization was performed to obtain 50.5g of intermediate In-1 as white crystals (yield 88%).

[0398] (2) Synthesis of onium salt type monomer a-1 Under a nitrogen atmosphere, intermediate In-1 (50.5g), raw material SM-3 (35.9g), methylene chloride (200g), and water (100g) were added to a reaction vessel and stirred for 30 minutes. The organic layer was then separated, washed with water, and concentrated under reduced pressure to obtain 64.8g of the target monomer a-1 as an oily substance (yield 97%).

[0399] MALDI TOF-MS: POSITIVE M + 335(C 18 H 11 F4S + equivalent) NEGATIVE M - 423(C 19 H7F4O5S - equivalent)

[0400] [Examples 1-2 to 1-7] Synthesis of onium salt type monomers a-2 to a-7 Using corresponding raw materials and known organic synthesis reactions, onium salt type monomers a-2 to a-7, represented by the following formulas, were synthesized. [ka]

[0401] [Comparative Examples 1-1 to 1-4] Synthesis of comparative onium salt type monomers Ca-1 to Ca-4 Using corresponding raw materials and known organic synthesis reactions, comparative onium salt monomers Ca-1 to Ca-4, represented by the following formulas, were synthesized. [ka]

[0402] [2] Synthesis of base polymers Of the monomers used in the synthesis of the base polymer, those other than onium salt monomers a-1 to a-7 and comparative onium salt monomers ca-1 to ca-4 are as follows: [ka]

[0403] [ka]

[0404] [ka]

[0405] [Example 2-1] Synthesis of Polymer P-1 Under a nitrogen atmosphere, monomer a-1 (41.8g), monomer b1-1 (45.1g), monomer c-1 (13.2g), 4.23g of V-601 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 140g of MEK were placed in a flask to prepare a monomer-polymerization initiator solution. In another flask under a nitrogen atmosphere, 46g of MEK was placed and heated to 80°C with stirring, and then the monomer-polymerization initiator solution was added dropwise over 4 hours. After the addition was complete, the polymerization solution was kept at 80°C and stirred for 2 hours, and then cooled to room temperature. The obtained polymerization solution was added dropwise to 3000g of hexane that had been vigorously stirred, and the precipitated polymer was filtered off. Furthermore, the obtained polymer was washed twice with 600g of hexane and then vacuum-dried at 50°C for 20 hours to obtain a white powdery polymer P-1 (yield 97.3g, yield 97%). The Mw of polymer P-1 was 9900, and the Mw / Mn ratio was 1.55. Note that Mw is a polystyrene-converted value measured by GPC using DMF as the solvent. [ka]

[0406] [Examples 2-2 to 2-30, Comparative Examples 2-1 to 2-24] Synthesis of polymers P-2 to P-30 and comparative polymers CP-1 to CP-24 The polymers shown in Tables 1 and 2 were produced in the same manner as in Example 2-1, except that the types and blending ratios of each monomer were changed.

[0407] [Table 1]

[0408] [Table 2]

[0409] [3] Preparation of resist composition [Examples 3-1 to 3-30, Comparative Examples 3-1 to 3-24] A predetermined component selected from the base polymers (P-1 to P-30), comparative base polymers (CP-1 to CP-24), photoacid generators (PAG-X, PAG-Y), and quenchers (Q-1 to Q-4) of the present invention was dissolved in a solvent containing 0.01% by mass of FC-4430 manufactured by 3M as a surfactant, in the compositions shown in Tables 3 and 4 below, to prepare a solution. This solution was then filtered through a 0.2 μm Teflon® type filter to prepare chemically amplified resist compositions (R-1 to R-30, CR-1 to CR-24).

[0410] [Table 3]

[0411] [Table 4]

[0412] In Tables 3 and 4, the solvent, photoacid generators PAG-X and PAG-Y, and quenchers Q-1 to Q-4 are as follows: • Solvent: PGMEA (Propylene glycol monomethyl ether acetate) EL (Ethyl Lactate) DAA (Diacetone Alcohol)

[0413] • Photoacid generators: PAG-X, PAG-Y [ka]

[0414] • Quencher: Q-1~Q-4 [ka]

[0415] [4] EUV lithography evaluation (1) [Examples 4-1 to 4-30, Comparative Examples 4-1 to 4-24] Each chemically amplified resist composition (R-1 to R-30, CR-1 to CR-24) shown in Tables 3 and 4 was spin-coated onto a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed to a thickness of 20 nm. A resist film with a thickness of 50 nm was then fabricated by pre-baking at 100°C for 60 seconds using a hot plate. The resist film was then exposed to an LS pattern with a wafer dimension of 18 nm and a pitch of 36 nm using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, dipole illumination), with exposure dose and focus varied (exposure dose pitch: 1 mJ / cm²). 2 The process was carried out while adjusting the focus pitch (0.020 μm), and after exposure, PEB was performed for 60 seconds at the temperatures shown in Tables 5 and 6. Then, paddle development was performed for 30 seconds with a 2.38 mass% TMAH aqueous solution, rinsed with a surfactant-containing rinse material, and spin-dried to obtain a positive type pattern. The obtained LS patterns were observed using a Hitachi High-Technologies Corporation length-measuring SEM (CG6300), and sensitivity, EL, LWR, depth of field (DOF), and tilt limit were evaluated according to the method described below. The results are shown in Tables 5 and 6.

[0416] [Sensitivity evaluation] The optimal exposure dose Eop(mJ / cm²) for obtaining an LS pattern with a line width of 18nm and a pitch of 36nm is obtained. 2 The value of ) was calculated and defined as the sensitivity. The smaller this value, the higher the sensitivity.

[0417] [EL rating] The exposure amount formed within ±10% (16.2 to 19.8 nm) of the 18 nm space width in the aforementioned LS pattern was used to calculate the EL (unit: %) using the following formula. A larger value indicates better performance. EL(%) = (|E1-E2| / Eop) × 100 E1: Optimal exposure amount to give an LS pattern with a line width of 16.2 nm and a pitch of 36 nm. E2: Optimal exposure amount to give an LS pattern with a line width of 19.8 nm and a pitch of 36 nm. Eop: Optimal exposure amount to give an LS pattern with a line width of 18nm and a pitch of 36nm.

[0418] [LWR rating] The LS pattern obtained by irradiating with Eop was measured at 10 points along the longitudinal direction of the line, and the LWR was calculated as three times the standard deviation (σ) (3σ) from these results. The smaller this value, the less roughness and the more uniform the line width pattern obtained.

[0419] [DOF rating] To evaluate the depth of focus, the focus range formed within ±10% of the 18nm dimension (16.2 to 19.8nm) in the aforementioned LS pattern was determined. A larger value indicates a wider depth of focus.

[0420] [Evaluation of the limit of line pattern collapse] The line dimensions for each exposure amount at the optimal focus of the aforementioned LS pattern were measured at 10 points along the longitudinal direction. The thinnest line dimension obtained without collapse was defined as the collapse limit dimension. The smaller this value, the better the collapse limit.

[0421] [Table 5]

[0422] [Table 6]

[0423] The results shown in Tables 5 and 6 indicate that the chemically amplified resist composition containing a polymer made from the onium salt type monomer of the present invention exhibits good sensitivity and excellent EL, LWR, and DOF. Furthermore, it was confirmed that the tilt limit value is small and that the pattern is resistant to tilting even in the formation of fine patterns. Therefore, the chemically amplified resist composition of the present invention is suitable as a material for EUV lithography.

[0424] [5] EUV Lithography Evaluation (2) [Examples 5-1 to 5-30, Comparative Examples 5-1 to 5-24] Each chemically amplified resist composition (R-1 to R-30, CR-1 to CR-24) shown in Tables 3 and 4 was spin-coated onto a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed to a thickness of 20 nm. The resist film was then pre-baked at 105°C for 60 seconds using a hot plate to produce a resist film with a thickness of 50 nm. The resist film was exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple pole illumination, wafer-mounted dimensions of 46 nm pitch, +20% bias hole pattern mask). PEB was performed using a hot plate at the temperatures listed in Tables 7 and 8 for 60 seconds, and development was performed with a 2.38% by mass TMAH aqueous solution for 30 seconds to form a hole pattern with dimensions of 23 nm. Using a Hitachi High-Technologies Corporation length-measuring SEM (CG6300), the exposure amount when a hole dimension of 23 nm was formed was measured and defined as the sensitivity. The dimensions of 50 holes at this point were also measured, and the CDU was defined as three times the standard deviation (σ) calculated from these results (3σ). The results are shown in Tables 7 and 8.

[0425] [Table 7]

[0426] [Table 8]

[0427] The results shown in Tables 7 and 8 confirm that the chemically amplified resist composition containing a polymer made from the sulfonium salt type monomer of the present invention exhibits good sensitivity and excellent CDU.

[0428] [6] Dry etching resistance evaluation [Examples 6-1 to 6-30, Comparative Examples 6-1 to 6-24] Two g of each polymer shown in Tables 1 and 2 (polymers P-1 to P-30, comparative polymers CP-1 to CP-24) was dissolved in 10 g of cyclohexanone, filtered through a 0.2 μm size filter, and the resulting polymer solution was spin-coated onto a Si substrate to a thickness of 300 nm. The dry etching resistance was then evaluated under the following conditions. Etching test with CHF3 / CF4 gas: The difference in polymer film thickness before and after etching was determined using the TE-8500P dry etching system manufactured by Tokyo Electron Ltd. The etching conditions are as follows: Chamber pressure 40 Pa RF Power 1000W Gap 9mm CHF3 gas flow rate: 30 mL / min CF4 gas flow rate: 30 mL / min Ar gas flow rate: 100 mL / min Time 60sec This evaluation indicates that materials with less film thickness variation, i.e., those with less reduction in film thickness, have higher etching resistance. The results of the dry etching resistance are shown in Tables 9 and 10.

[0429] [Table 9]

[0430] [Table 10]

[0431] The results shown in Tables 9 and 10 confirm that the polymer of the present invention has excellent dry etching resistance to CHF3 / CF4 gases.

Claims

1. An onium salt type monomer represented by the following formula (A). 【Chemistry 1】 (In the formula, n1 is 0, 1, 2, 3 or 4; n2 is 0 or 1; n3 is 0, 1, 2, 3 or 4; n4 is 0, 1, 2, 3 or 4, except when n2 is 0, 0 ≤ n3 + n4 ≤ 4, and when n2 is 1, 0 ≤ n3 + n4 ≤ 6.) R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 1 This is a C1-C20 hydrocarbyl group which may contain a halogen atom, a hydroxyl group, a nitro group, a cyano group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, or a C1-C20 hydrocarbylthio group which may contain a heteroatom. When n1 is 2, 3, or 4, each R 1 They may be the same or different from each other, and there may be multiple R 1 These atoms may bond with each other to form a ring with the carbon atoms to which they are bonded. R 2 This is a halogen atom other than a fluorine atom, a nitro group, a hydroxyl group, a C1-C20 hydrocarbyl group, a C1-C20 hydrocarbyloxy group, or a C1-C20 hydrocarbylthio group, and the hydrocarbyl group, hydrocarbyloxy group, and hydrocarbylthio group may contain heteroatoms other than a fluorine atom. When n4 is 2, 3, or 4, each R 2 They may be the same or different from each other, and there may be multiple R 2 These atoms may bond with each other to form a ring with the carbon atoms to which they are bonded. R F is a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a fluorinated saturated hydrocarbyloxy group having 1 to 6 carbon atoms, or a fluorinated saturated hydrocarbylthio group having 1 to 6 carbon atoms. When n3 is 2, 3, or 4, each R F may be the same as or different from each other. L A and L B These are, independently, a single bond, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, or a carbamate bond. X L1 This is a hydroxylene group having 1 to 40 carbon atoms, which may contain single bonds or heteroatoms. Z + This is an onium cation.

2. The onium salt type monomer according to claim 1, which is represented by the following formula (A1). 【Chemistry 2】 (In the formula, n1, n3, n4, R A , R 1 , R 2 , R F , L A , L B , X L1 and Z + (This is the same as above.)

3. The onium salt type monomer according to claim 2, which is represented by the following formula (A2). 【Transformation 3】 (In the formula, n1, R A , R 1 , L A , L B , X L1 and Z + (This is the same as above.)

4. Z + The onium salt type monomer according to claim 1, wherein the sulfonium cation represented by the following formula (Z-1) or the iodonium cation represented by the following formula (Z-2). 【Chemistry 4】 (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. ct1 and R ct2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded.

5. Z + The polymer according to claim 1, wherein the cation is a sulfonium cation represented by the following formula (Z-3). 【Transformation 5】 (In the formula, m1 is 0 or 1. m2 is 0 or 1. m3 is 0 or 1. m4 is 0, 1, 2, 3 or 4. m5 is 0, 1, 2, 3 or 4. m6 is 0, 1, 2, 3, 4, 5 or 6. m7 is 0, 1, 2, 3, 4, 5 or 6. m8 is 0, 1 or 2. m9 is 0, 1 or 2. m10 is 0, 1 or 2. m11 is 0 or 1. m12 is 0, 1, 2, 3 or 4. m13 is 0, 1 or 2. m14 is 0, It is either 1 or 2. However, when m1 is 0, 0 ≤ m6 + m9 ≤ 4, and when m1 is 1, 0 ≤ m6 + m9 ≤ 6. When m2 is 0, 0 ≤ m7 + m10 ≤ 4, and when m2 is 1, 0 ≤ m7 + m10 ≤ 6. When m3 is 0, 1 ≤ m4 + m5 + m8 + m14 ≤ 4, and when m3 is 1, 1 ≤ m4 + m5 + m8 + m14 ≤ 6. When m11 is 0, 0 ≤ m12 + m13 ≤ 4, and when m11 is 1, 0 ≤ m12 + m13 ≤ 6. Also, m4 + m12 ≥ 1. R F1 ~R F3 Each of these is independently a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a fluorinated saturated hydrocarbyloxy group having 1 to 6 carbon atoms, or a fluorinated saturated hydrocarbylthio group having 1 to 6 carbon atoms. When m5 is 2, 3, or 4, each R F1 They may be the same as or different from each other. When m6 is 2, 3, 4, 5 or 6, each R F2 They may be the same as or different from each other. When m7 is 2, 3, 4, 5 or 6, each R F3 They may be the same or different from one another. R ct6 ~R ct9 This is a C1-C20 hydrocarbyl group which may contain halogen atoms other than iodine and fluorine atoms, a nitro group, a cyano group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, or a C1-C20 hydrocarbylthio group which may contain a heteroatom. When m8 is 2, two R ct6 The two Rs may be the same or different from each other. ct6 These may bond with each other to form a ring with the carbon atoms to which they are bonded. When m9 is 2, two R ct7 The two Rs may be the same or different from each other. ct7 These may bond with each other to form a ring with the carbon atoms to which they are bonded. When m10 is 2, two R ct8 The two Rs may be the same or different from each other. ct8 These may bond with each other to form a ring with the carbon atoms to which they are bonded. When m13 is 2, two R ct9 The two Rs may be the same or different from each other. ct9 These atoms may bond with each other to form a ring with the carbon atoms to which they are bonded. Furthermore, S in sulfonium cations + Aromatic rings that are directly bonded to each other are bonded to each other and form S + They may form a ring together. L C and L D These are, independently, a single bond, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, or a carbamate bond. X L2 This is a hydrocarbylene group having 1 to 40 carbon atoms, which may contain single bonds or heteroatoms.

6. A polymer comprising repeating units derived from an onium salt type monomer according to any one of claims 1 to 4.

7. The polymer according to claim 6, which functions as a polymer-bound acid generator.

8. Furthermore, the polymer according to claim 6 comprises at least one selected from the repeating units represented by the following formula (a1), the repeating unit represented by the following formula (a2), and the repeating unit represented by the following formula (a3). 【Transformation 6】 (In the formula, R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 This consists of a single bond, a phenylene group, a naphthylene group, and *-C(=O)-O-X 11 - or * - C (= O) - NH - X 11 - and the phenylene group or naphthylene group may be substituted with a hydroxyl group, a nitro group, a cyano group, a saturated hydrocarbyl group having 1 to 10 carbon atoms which may contain a fluorine atom, a saturated hydrocarbyloxy group having 1 to 10 carbon atoms which may contain a fluorine atom, or a halogen atom. 11 This is a saturated hydrocarbylene group, a phenylene group, or a naphthylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. X 2 These are single bonds, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain. R 11 This is a C1-C20 hydrocarbyl group which may contain a halogen atom, a cyano group, a hydroxyl group, a nitro group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. When a1 is 2, 3, or 4, each R 11 They may be the same as or different from each other. AL 1 and AL 2 These are, independently, acid-unstable groups. a1 is 0, 1, 2, 3, or 4. 【Transformation 7】 (In the formula, a11 is 0 or 1. a12 is 0, 1, 2 or 3 when a11 is 0, and 0, 1, 2, 3, 4 or 5 when a11 is 1.) R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 3 The bonds are single bonds, *-C(=O)-O-, or *-C(=O)-NH-. The asterisk (*) represents a bond with a carbon atom in the main chain. X 4 This refers to a single bond, an aliphatic hydrocarbylene group having 1 to 4 carbon atoms, a carbonyl group, a sulfonyl group, or a group obtained by combining these. X 5 and X 6 Each of these is independently either an oxygen atom or a sulfur atom. However, X 4 and X 6 It is bonded to the carbon atom adjacent to the aromatic ring. R 12 and R 13 Each of these is independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom or a heteroatom. Also, R 12 and R 13 However, they may bond with each other to form a ring with the carbon atoms to which they are bonded. R 14 This may include a halogen atom, a hydroxyl group, a cyano group, a nitro group, a C1-C20 hydrocarbyl group which may contain a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom, a C1-C20 hydrocarbylthio group which may contain a heteroatom, or -N(R) 14A )(R 14B ) is R 14A and R 14B Each is independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms. When a12 is 2 or more, each R 14 These may be the same or different from each other, and there may be multiple R 14 However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded.

9. Furthermore, the polymer according to claim 6 comprises at least one selected from the repeating units represented by the following formula (b1) and the repeating units represented by the following formula (b2). 【Transformation 8】 (In the formula, R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 The bond is either a single bond or *-C(=O)-O-. The asterisk (*) represents a bond with a carbon atom in the main chain. R 21 This is a group having 1 to 20 carbon atoms that includes a hydrogen atom or at least one structure selected from a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride (-C(=O)-O-C(=O)-). R 22 This is a C1-C20 hydrocarbyl group which may contain a halogen atom, a carboxyl group, a nitro group, a cyano group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. When b2 is 2, 3, or 4, each R 22 They may be the same as or different from each other. b1 is 1, 2, 3, or 4. b2 is 0, 1, 2, 3, or 4, where 1 ≤ b1 + b2 ≤ 5.

10. (A) A chemically amplified resist composition comprising a base polymer containing the polymer described in claim 6.

11. Furthermore, the chemically amplified resist composition according to claim 10, further comprising (B) an organic solvent.

12. Furthermore, the chemically amplified resist composition according to claim 10, further comprising (C) a quencher.

13. Furthermore, the chemically amplified resist composition according to claim 10, further comprising (D) a photoacid generator.

14. Furthermore, the chemically amplified resist composition according to claim 10, further comprising (E) a surfactant.

15. A pattern forming method comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition according to claim 10; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer.

16. The pattern formation method according to claim 15, wherein 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.

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