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

Abstract

Provided are: an onium salt monomer used as a monomeric photoacid generator, which is a material for a polymer contained in a chemically amplified resist composition that exhibits excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance in photolithography using high-energy rays; a monomeric photoacid generator comprising the onium salt monomer; a polymer containing a repeating unit derived from the monomeric photoacid generator; and a chemically amplified resist composition that contains a base polymer containing the polymer; and a pattern formation method that uses the chemically amplified resist composition. The onium salt type monomer is characterized by being an onium salt type monomer represented by the following general formula (A): [Formula 1] TIFF2026043544000293.tif37121

Description

[Technical Field]

[0001] The present invention relates to an onium salt-type monomer, a monomer-type photoacid generator, a polymer, a chemically amplified resist composition, and a pattern forming method. [Background technology]

[0002] As LSIs become more highly integrated and faster, pattern rules are becoming increasingly finer. The expansion of the flash memory market and the increasing storage capacity are driving this trend. The most advanced miniaturization technology is ArF lithography, which is currently used to mass-produce 65nm node devices, and preparations are underway for mass production of next-generation 45nm node devices using ArF immersion lithography. For next-generation 32nm node devices, immersion lithography using an ultra-high NA lens that combines 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 candidates for which investigation is underway.

[0003] As miniaturization progresses and approaches the diffraction limit of light, the optical contrast decreases, which in turn causes a decrease in the resolution of hole and trench patterns and a decrease in focus margin in positive resist films.

[0004] As patterns become finer, line width roughness (LWR) of line patterns and dimensional uniformity (CDU) of hole patterns become issues. 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, as resist films become thinner, LWR tends to increase, and the deterioration of LWR due to thinning accompanying the progress of miniaturization is becoming a serious problem.

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

[0006] To suppress acid diffusion, resist compounds containing repeating units derived from onium salts of sulfonic acids with polymerizable unsaturated bonds have been proposed (Patent Document 1). Such so-called polymer-bound acid generators are characterized by extremely short acid diffusion times because they generate polymeric sulfonic acids upon exposure. Furthermore, increasing the proportion of acid generator can improve sensitivity. Increasing the amount of additive-type acid generators also increases sensitivity, but in this case, the acid diffusion distance also increases. Because acid diffuses unevenly, increased acid diffusion leads to deterioration of LWR and CDU. It can be said that polymer-type acid generators have a high ability to balance sensitivity, LWR, and CDU.

[0007] Because iodine atoms have a very high absorption rate for EUV light with a wavelength of 13.5 nm, the effect of generating secondary electrons from iodine atoms during exposure has been confirmed, and this has attracted attention in EUV lithography. Patent Document 2 describes a photoacid generator in which an iodine atom has been introduced into the anion, and Patent Document 3 describes a polymerizable group-containing photoacid generator in which an iodine atom has been introduced into the anion. While these have been confirmed to improve lithography performance to a certain extent, iodine atoms are not highly soluble in organic solvents, and there is a concern that they may precipitate in the solvent.

[0008] Patent Documents 4 and 5 describe photoacid generators in which a pentafluorosulfanyl group (-SF5 group) or a trifluoromethoxy group (-OCF3 group) is introduced into the cation. Although these have led to some progress in improving lithography performance, there is still room for improvement, and the development of resist materials that are more effective in forming 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] International Publication No. 2023 / 223624 [Patent Document 5] Japanese Patent Publication No. 2022-059112 Summary of the Invention [Problem to be solved by the invention]

[0010] There is a demand for the development of acid-catalyzed chemically amplified resist compositions that have even higher sensitivity and are capable of improving lithography performance such as exposure latitude (EL), LWR, CDU, and depth of focus (DOF).

[0011] The present invention has been made in view of the above circumstances, and has an object to provide an onium salt monomer used as a monomeric photoacid generator, which is a material for a polymer contained in a chemically amplified resist composition that exhibits excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance in photolithography using high-energy rays; a monomeric photoacid generator comprising the onium salt monomer; a polymer containing a repeating unit derived from the monomeric photoacid generator; and a chemically amplified resist composition that contains a base polymer containing the polymer; and a pattern formation method that uses the chemically amplified resist composition. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides an onium salt type monomer represented by the following general formula (A): [ka] (In the formula, n1 is 0 or 1. n2 is an integer of 1 to 4. n3 is an integer of 0 to 4. However, when n1 is 0, 1≦n2+n3≦4, and when n1 is 1, 1≦n2+n3≦6. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 1 is a halogen atom other than an iodine atom, a nitro group, a hydroxy group, a carboxy group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms. When n3 is 2, 3, or 4, each R 1 may be the same or different, and multiple R 1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 2 is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L A is a single bond, an ether bond, an ester bond, or a sulfonate ester bond. L B , L C and L D are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, or a carbamate bond. X L1 and X L2 are each independently a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. R F is a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Z + indicates an onium cation.)

[0013] Such an onium salt monomer can be used as a monomeric photoacid generator, and a chemically amplified resist composition comprising a base polymer that includes a polymer containing a repeating unit derived from the monomeric photoacid generator exhibits excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance in photolithography using high-energy rays.

[0014] In the present invention, the onium salt type monomer is preferably represented by the following general formula (A1). [ka] (In the formula, R A , R 1 , R 2 , R F , L A , L B , L C , X L1 , X L2 , n1 to n3 and Z + is the same as above.)

[0015] The onium salt type monomer of the present invention preferably has such a structure.

[0016] In this case, the onium salt type monomer represented by the general formula (A1) is preferably represented by the following general formula (A2). [ka] (In the formula, R A , R 1 , R 2 , R F , L C , X L2 , n1 to n3 and Z + is the same as above.)

[0017] The onium salt type monomer of the present invention more preferably has such a structure.

[0018] In the present invention, the Z + is preferably a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2). [ka] (In the formula, R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0019] The onium salt type monomer of the present invention preferably has such a cation.

[0020] The present invention also provides a monomeric photoacid generator, which is made from the onium salt monomer described above.

[0021] If such a monomeric photoacid generator is used, a chemically amplified resist composition containing a base polymer including a polymer containing a repeating unit derived from this monomeric photoacid generator will have excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance in photolithography using high-energy rays.

[0022] The present invention also provides a polymer that contains a repeating unit derived from the above-described monomeric photoacid generator.

[0023] If such a polymer is used, a chemically amplified resist composition containing a base polymer containing this polymer will have excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance in photolithography using high-energy rays.

[0024] In the present invention, it is preferable that the polymer further contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following general formula (a1), a repeating unit represented by the following general formula (a2), and a repeating unit represented by the following general formula (a3). [ka] (In the formula, a1 is an integer of 0 to 4. R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 11 -, and the phenylene group or naphthylene group may be substituted with a hydroxy 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 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. X 2 is a single bond or *-C(=O)-O-. * indicates a bond to a carbon atom in the main chain. R 21 is a halogen atom, a cyano group, a hydroxy group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. 21 may be the same as or different from each other. AL 1and AL 2 are each independently an acid labile group. [ka] (In the formula, b1 is 0 or 1. When b1 is 0, b2 is an integer of 0 to 3, and when b1 is 1, b2 is an integer of 0 to 5. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 3 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. X 4 is 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 are each independently an oxygen atom or a sulfur atom, provided that X 4 and X 6 are attached to adjacent carbon atoms of the aromatic ring. R 22 and R 23 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 22 and R 23 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 24 is a halogen atom, a hydroxy group, a cyano group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, or —N(R 24A )(R 24B ) is R 24A and R 24B are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms. When b2 is 2 or more, each R 24may be the same or different, and multiple R 24 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached.)

[0025] In the present invention, it is preferable that the polymer further contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following general formula (b1) and a repeating unit represented by the following general formula (b2). [ka] (In the formula, c1 is an integer of 1 to 4, and c2 is an integer of 0 to 4, provided that 1≦c1+c2≦5. R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 31 is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-). R 32 is a halogen atom, a carboxy group, a nitro group, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. 32 may be the same as or different from each other.)

[0026] The polymer of the present invention preferably has such a repeating unit.

[0027] The present invention also provides a chemically amplified resist composition, which comprises (A) a base polymer containing the above-described polymer.

[0028] Such a chemically amplified resist composition exhibits excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance in photolithography using high-energy rays.

[0029] In this case, it is preferable that the chemically amplified resist composition further contains one or more selected from (B) an organic solvent, (C) a quencher, (D) a photoacid generator other than the monomeric photoacid generator, and (E) a surfactant.

[0030] The chemically amplified resist composition of the present invention may contain these additives.

[0031] The present invention also provides a pattern formation method, which includes the steps of forming a resist film on a substrate using the chemically amplified resist composition described above, exposing the resist film to high-energy rays, and developing the exposed resist film using a developer.

[0032] Such a pattern formation method can provide a pattern formation method using a chemically amplified resist composition that has excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance in photolithography using high-energy rays.

[0033] In this case, it is preferable to use KrF excimer laser light, ArF excimer laser light, electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm as the high energy beam.

[0034] Such a beam can be used as the high energy beam. [Effects of the Invention]

[0035] As described above, when a pattern is formed using a chemically amplified resist composition comprising a base polymer that includes a polymer containing a repeating unit that functions as a photoacid generator derived from a monomeric photoacid generator composed of an onium salt-type monomer of the present invention, it is possible to form a resist pattern that has excellent solvent solubility, high contrast, and good sensitivity, and that is excellent in lithography performance such as EL, LWR, CDU, and DOF, particularly in photolithography that uses high-energy rays such as KrF excimer laser light, ArF excimer laser light, electron beam (EB), and EUV. DETAILED DESCRIPTION OF THE INVENTION

[0036] As described above, there has been a need for the development of an onium salt monomer to be used as a monomeric photoacid generator, which is a material for a polymer contained in a chemically amplified resist composition that exhibits excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance in photolithography using high-energy rays; a monomeric photoacid generator comprising the onium salt monomer; a polymer containing a repeating unit derived from the monomeric photoacid generator; a chemically amplified resist composition containing a base polymer that contains the polymer; and a pattern formation method using the chemically amplified resist composition.

[0037] As a result of extensive research into achieving the above-mentioned object, the present inventors have found that by using a polymer containing a repeating unit derived from an onium salt-type monomer having a polymerizable group, an iodine-containing aromatic ring, and an α-fluoroalkanesulfonate anion structure as a polymer-bonded acid generator, it is possible to obtain a chemically amplified resist composition that has good sensitivity, improved lithography performance such as EL, LWR, CDU, and DOF, and that has high contrast and high resolution, and has completed the present invention.

[0038] That is, the present invention relates to an onium salt type monomer, which is represented by the following general formula (A). [ka] (In the formula, n1 is 0 or 1. n2 is an integer of 1 to 4. n3 is an integer of 0 to 4. However, when n1 is 0, 1≦n2+n3≦4, and when n1 is 1, 1≦n2+n3≦6. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 1 is a halogen atom other than an iodine atom, a nitro group, a hydroxy group, a carboxy group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms. When n3 is 2, 3, or 4, each R 1 may be the same or different, and multiple R 1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 2 is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L A is a single bond, an ether bond, an ester bond, or a sulfonate ester bond. L B , L C and L D are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, or a carbamate bond. X L1 and X L2 are each independently a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. R F is a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Z + indicates an onium cation.)

[0039] The present invention will be described in detail below. In the following description, some structures represented by chemical formulas may have asymmetric carbon atoms, and enantiomers or diastereomers may exist. In such cases, a single formula will be used to represent all isomers. These isomers may be used singly or as a mixture of two or more.

[0040] [Onium salt type monomer] The onium salt type monomer of the present invention is represented by the following general formula (A). [ka] (In the formula, n1 is 0 or 1. n2 is an integer of 1 to 4. n3 is an integer of 0 to 4. However, when n1 is 0, 1≦n2+n3≦4, and when n1 is 1, 1≦n2+n3≦6. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 1 is a halogen atom other than an iodine atom, a nitro group, a hydroxy group, a carboxy group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms. When n3 is 2, 3, or 4, each R 1 may be the same or different, and multiple R 1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 2 is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L A is a single bond, an ether bond, an ester bond, or a sulfonate ester bond. L B , L C and L Dare each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, or a carbamate bond. X L1 and X L2 are each independently a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. R F is a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Z + indicates an onium cation.)

[0041] In the above general formula (A), n1 is 0 or 1. When n1 is 0, it is a benzene ring, and when n1 is 1, it is a naphthalene ring, but from the viewpoint of solvent solubility, n1 is preferably a benzene ring of 0. n2 is an integer of 1 to 4. The greater the number of iodine atoms in the anion structure, the higher the absorption, particularly with respect to EUV, but since solvent solubility becomes poor and there is a concern of precipitation in the resist composition, n2 is preferably 1, 2, or 3, and more preferably 1 or 2. n3 is an integer of 0 to 4. From the viewpoint of raw material procurement, n3 is preferably 0 or 1.

[0042] In the above general formula (A), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Among these, a hydrogen atom or a methyl group is preferred.

[0043] In the above general formula (A), R 1is a halogen atom other than an iodine atom, a nitro group, a hydroxy group, a carboxy group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom. The hydrocarbyl group and the hydrocarbyl moiety of the hydrocarbyloxy group and hydrocarbylthio group may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms 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 icosyl groups; cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclopropyl, and the like. Examples of such groups include saturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as hexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, 1-propenyl, 2-propenyl, butenyl, and hexenyl; unsaturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 20 carbon atoms, such as phenyl and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining these groups. Of these, aryl groups are preferred.In addition, 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 or a halogen atom, and some of the -CH2- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, so that the hydrocarbyl group 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 sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. When n3 is 2, 3 or 4, each R. 1 may be the same as or different from each other.

[0044] Also, when n3 is 2, 3, or 4, multiple R 1 may be bonded to 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 a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, and an adamantane ring. 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 -CH- groups in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the ring containing 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 sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0045] In the above general formula (A), R 2 is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 1 From the viewpoint of raw material procurement, R 2 is preferably a hydrogen atom.

[0046] In the above general formula (A), R F is a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. The fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms is preferably a trifluoromethyl group.

[0047] In the above general formula (A), L A is a single bond, an ether bond, an ester bond, or a sulfonate ester bond. B and X L1 When both are single bonds, L A is preferably a single bond.

[0048] In the above general formula (A), L B , L C and L D are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, or a carbamate bond. B is preferably a single bond, an ether bond, an ester bond, or a sulfonate ester bond, and more preferably a single bond, an ether bond, or an ester bond. C is preferably a single bond, an ether bond, an ester bond, or a sulfonate ester bond, and more preferably a single bond, an ether bond, or an ester bond. D is preferably a single bond, an ether bond, an ester bond, or a sulfonate ester bond, and more preferably an ether bond or an ester bond.

[0049] In the above general formula (A), X L1 and X L2 is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbylene group may be linear, branched, or cyclic, and specific examples thereof include an alkanediyl group and a cyclic saturated hydrocarbylene group. Specific examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom.

[0050] X L1 and X L2 Specific examples of the hydrocarbylene group having 1 to 40 carbon atoms and optionally containing a hetero atom, represented by the formula (I), include, but are not limited to, those shown below. In the formula (I), * represents L A and L B , L C and L D It is a combination of.

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055] Of these, X L -0~X L -22, X L -29~X L -34 and X L -47~X L -58 is preferred.

[0056] From the viewpoint of the rigidity of the resulting polymer, X L1 and X L2 is preferably a single bond.

[0057] The onium salt monomer is preferably represented by the following general formula (A1). [ka] (In the formula, R A , R 1 , R 2 , R F , L A , L B , L C , X L1 , X L2 , n1 to n3 and Z + is the same as above.)

[0058] The onium salt monomer represented by the above general formula (A1) is preferably represented by the following general formula (A2). [ka] (In the formula, R A , R 1 , R 2 , R F , L C , X L2 , n1 to n3 and Z + is the same as above.)

[0059] Specific examples of the anion of the onium salt type monomer represented by the above general formula (A) include, but are not limited to, those shown below. A is the same as above, and Me is a methyl group. The bonding positions of the various substituents on the aromatic ring may be interchanged.

[0060] [ka]

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[0121] In the above general formula (A), Z + is an onium cation. + is preferably a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2). [ka] (In the formula, R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0122] In the above general 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 heteroatom.

[0123] R ct1 ~R ct5Specific examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0124] R ct1 ~R ct5 The hydrocarbyl group represented by the formula (I) 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, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; saturated cyclic hydrocarbyl groups having 3 to 30 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 30 carbon atoms, such as vinyl, 1-propenyl, 2-propenyl, butenyl, and hexenyl; unsaturated cyclic hydrocarbyl groups having 3 to 30 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 30 carbon atoms, such as phenyl, naphthyl, and thienyl; aralkyl groups having 7 to 30 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining these, with aryl groups being preferred. 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, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group 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 sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc.

[0125] Also, R ct1 and R ct2 However, they may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, specific examples of the ring structure include those represented by the following formulas. [ka] (In the formula, the dashed line indicates R ct3 )

[0126] Specific examples of the sulfonium cation represented by the general formula (Z-1) are those described in paragraphs

[0102] to

[0125] of JP-A-2024-003744, those described in paragraphs

[0070] to

[0085] of JP-A-2023-169812, those described in paragraphs

[0044] to

[0049] of WO 2024 / 128017, and those described in paragraphs

[0035] to

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

[0127] Specific examples of the iodonium cation represented by the general formula (Z-2) include, but are not limited to, those described in paragraph

[0181] of JP-A No. 2024-000259.

[0128] Z + As the onium cation represented by the formula (Z-1), a sulfonium cation represented by the following formula (Z-3) is also preferred. [ka]

[0129] In the above general formula (Z-3), m1 is 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 preferably a benzene ring with m1 being 0. m2 is 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 preferably a benzene ring with m2 being 0. m3 is 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 preferably a benzene ring with m3 being 0.

[0130] In the above general formula (Z-3), m4 is an integer of 0 to 4. As the number of iodine atoms in the cation structure increases, absorption, particularly of EUV, increases. However, solvent solubility decreases, and there is a concern that precipitation may occur in the resist composition. Therefore, m4 is preferably an integer of 0 to 3, and more preferably 0, 1, or 2.

[0131] In the above general formula (Z-3), m5 is an integer of 0 to 4. From the viewpoint of raw material procurement, m5 is preferably an integer of 0 to 3, and more preferably 0, 1, or 2. m6 is an integer of 0 to 6. From the viewpoint of raw material procurement, m6 is preferably an integer of 0 to 3, and more preferably 0, 1, or 2. m7 is an integer of 0 to 6. From the viewpoint of raw material procurement, m7 is preferably an integer of 0 to 3, and more preferably 0, 1, or 2.

[0132] In the above general formula (Z-3), m8 is 0, 1, or 2. From the viewpoint of raw material procurement, m8 is preferably 0 or 1. m9 is 0, 1, or 2. From the viewpoint of raw material procurement, m9 is preferably 0 or 1. m10 is 0, 1, or 2. From the viewpoint of raw material procurement, m10 is preferably 0 or 1.

[0133] In the above general formula (Z-3), m11 is 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, it is preferable that m11 is 0 and is a benzene ring.

[0134] In the above general formula (Z-3), m12 is an integer of 0 to 4. As the number of iodine atoms in the cation structure increases, absorption, particularly of EUV, increases. However, solvent solubility decreases, and there is a concern that precipitation may occur in the resist composition. Therefore, m12 is preferably an integer of 0 to 3, and more preferably 0, 1, or 2.

[0135] In the above general formula (Z-3), m13 is 0, 1 or 2. From the viewpoint of raw material procurement, m13 is preferably 0 or 1. m14 is 0, 1 or 2. From the viewpoint of synthesis, m14 is preferably 0 or 1.

[0136] 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, 1≦m4+m12.

[0137] In the above general formula (Z-3), R F1 ~R F3 are each 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, a trifluoromethyl group, a trifluoromethoxy group, or a trifluorothiomethoxy group is preferred. When m5 is 2 or more, each R F1 may be the same or different, and when m6 is 2 or more, each R F2 may be the same or different, and when m7 is 2 or more, each R F3 may be the same or different from each other.

[0138] In the above general formula (Z-3), R ct6 ~R ct9is a halogen atom other than iodine atom and fluorine atom, a nitro group, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain 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. The hydrocarbyl group and the hydrocarbyl moiety of the hydrocarbyloxy group and hydrocarbylthio group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 1 In addition, some or all of the hydrogen atoms in the hydrocarbyl moiety of the hydrocarbyl group, hydrocarbyloxy group, and hydrocarbylthio 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- in the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, so that the hydrocarbyl group may contain a hydroxy group, cyano group, fluorine atom, chlorine atom, bromine atom, iodine atom, carbonyl group, ether bond, ester bond, sulfonate ester bond, carbonate bond, lactone ring, sultone ring, carboxylic anhydride (-C(=O)-OC(=O)-), haloalkyl group, etc.

[0139] Also, when m8 is 2, two R ct6 may be the same or different, and two R ct6 may be bonded to each other to form a ring together with the carbon atoms to which they are attached, and when m9 is 2, two R ct7 may be the same or different, and two R ct7 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded, and when m10 is 2, two R ct8 may be the same or different, and two R ct8 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded, and when m13 is 2, two R ct9 may be the same or different, and two R ct9may 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 in this case include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, and an adamantane ring. 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 -CH- groups in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the ring containing 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 sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0140] In addition, S in the sulfonium cation represented by the general formula (Z-3) + The aromatic rings directly bonded to S + In this case, specific examples of the ring structure include those represented by the following formulas: [ka] (In the formula, the dashed lines represent bonds.)

[0141] In the above general formula (Z-3), L C2 and L D2 are each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a sulfonate amide bond, a carbonate bond, or a carbamate bond. C2 is preferably a single bond, an ether bond, an ester bond, or a sulfonate ester bond, and more preferably an ester bond or a sulfonate ester bond. D2 is preferably a single bond, an ether bond, or an ester bond, and more preferably a single bond.

[0142] In the general formula (Z-3), XL is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbylene group may be linear, branched, or cyclic, and specific examples thereof include an alkanediyl group, a cyclic saturated hydrocarbylene group, and an arylene group. Specific examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom.

[0143] X L Specific examples of the hydrocarbylene group having 1 to 40 carbon atoms and optionally containing a hetero atom are: L1 and X L2 Examples include, but are not limited to, the same as those listed above.

[0144] The sulfonium cation represented by the above general formula (Z-3) is preferably one represented by the following general formula (Z-3-1). [ka] (In the formula, m4~m10, m12~m14, R F1 ~R F3 , R ct6 ~R ct9 , L C2 , L D2 and X L is the same as above.)

[0145] The sulfonium cation represented by the above general formula (Z-3-1) is preferably one represented by the following general formula (Z-3-2). [ka] (In the formula, m4~m10, R F1 ~R F3 and R ct6 ~R ct8 is the same as above.)

[0146] Specific examples of the sulfonium cation represented by the above general formula (Z-3) include, but are not limited to, the following: In the following formula, Me is a methyl group.

[0147] [ka]

[0148] [ka]

[0149] [ka]

[0150] [ka]

[0151] [ka]

[0152] [ka]

[0153] [ka]

[0154] [ka]

[0155] [ka]

[0156] [ka]

[0157]

change

[0158]

change

[0159]

change

[0160]

change

[0161]

change

[0162]

change

[0163]

change

[0164]

change

[0165]

change

[0166]

change

[0167] [ka]

[0168] [ka]

[0169] [ka]

[0170] [ka]

[0171] [ka]

[0172] [ka]

[0173] [ka]

[0174] [ka]

[0175] Specific examples of the onium salt type monomer of the present invention include any combination of the above-mentioned anions and cations.

[0176] The onium salt monomer of the present invention can be synthesized by a known method. As an example, a method for producing an onium salt monomer represented by the following general formula (PAG-A-ex) will be described, but the synthesis method is not limited thereto. [ka] (In the formula, R A , R 1 , R 2 , R F , L A , L B , X L1 , n1 to n3 and Z + is the same as above. M + is the counter cation. X - is the counter anion.)

[0177] The first step is to obtain intermediate In-1-ex by hydrolyzing the ester moiety of starting material SM-1, which is commercially available or obtained by a known synthetic method, followed by a neutralization reaction. The hydrolysis of the ester of starting material SM-1 is preferably carried out under basic conditions, and alkali metal hydroxides such as sodium hydroxide and potassium hydroxide are preferably used as the base. Starting material SM-1 is dissolved in a solvent such as tetrahydrofuran or 1,4-dioxane, and a base is added to carry out the reaction. To ensure smooth reaction progress, the reaction can be heated, if necessary. From the perspective of yield, it is desirable to monitor the reaction by silica gel thin-layer chromatography (TLC) to complete the reaction, but the reaction time is usually about 4 to 12 hours. After confirming the progress of the reaction, a neutralization reaction is carried out by adding an acid in slight excess over the base used. A strong acid is preferably used, and specific examples include hydrochloric acid, sulfuric acid, and nitric acid. After the neutralization reaction, the solvent is concentrated to obtain intermediate In-1-ex, which can be purified, if necessary, by conventional methods such as chromatography or recrystallization.

[0178] The second step is the reaction of intermediate In-1-ex with starting material SM-2 to obtain intermediate In-2-ex. Various condensation agents can be used to directly form an ester bond between the carboxy group of intermediate In-1-ex and the hydroxy group of starting material SM-2. Examples of condensation agents include N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. However, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is preferred because of the ease of removing the urea compound generated as a by-product after the reaction. The reaction is carried out by dissolving intermediate In-1-ex and starting material SM-2 in a halogen-based solvent such as methylene chloride and adding a condensation agent. The addition of 4-dimethylaminopyridine as a catalyst can improve the reaction rate. The reaction time is usually about 12 to 24 hours, although it is desirable to monitor the reaction by silica gel thin layer chromatography (TLC) to complete the reaction from the viewpoint of yield. After the reaction is stopped, the by-product urea compound is removed by filtration or washing with water, if necessary, and the reaction solution is then subjected to a conventional aqueous work-up to obtain intermediate In-2-ex. If necessary, the obtained intermediate In-2-ex can be purified by conventional methods such as chromatography or recrystallization.

[0179] In the third step, the obtained intermediate In-2-ex is converted to Z + X - This is a process for obtaining an onium salt type monomer (PAG-A-ex) by salt exchange with an onium salt (raw material SM-3) represented by the formula: -The preferred exchange anions are chloride ions, bromide ions, iodide ions, or methyl sulfate anions, as these facilitate quantitative exchange reactions. The reaction time is typically about 4 to 12 hours, although it is desirable to monitor the reaction by TLC to ensure the reaction is complete from the standpoint of yield. The onium salt monomer (PAG-1-ex) can be obtained from the reaction mixture by conventional aqueous workup. If necessary, the product can be purified by conventional methods such as chromatography or recrystallization.

[0180] In the above scheme, the ion exchange in the third step can be easily carried out by a known method, for example, see JP-A-2007-145797.

[0181] The above-mentioned production method is merely an example, and the production method of the onium salt type monomer of the present invention is not limited to this.

[0182] The structural features of the onium salt monomer of the present invention include an aromatic ring containing an iodine atom and an α-fluoro (or fluoroalkyl) sulfonate anion structure. Regarding iodine atoms, the absorption of EUV light by iodine atoms is particularly strong in EUV lithography at a wavelength of 13.5 nm, resulting in the generation of secondary electrons from the iodine atoms during exposure. Because the onium salt monomer of the present invention has a polymerizable group in the anion moiety, the polymer of the present invention obtained using a monomeric photoacid generator comprising this monomer becomes an anion-bound photoacid generator in which the anion side is bound to the polymer main chain. In other words, because acid is generated bound to the main chain of the polymer, diffusion of the generated acid can be suppressed. Furthermore, polymerizable groups, particularly those containing styrene or vinylnaphthalene structures, are more rigid than polymerizable groups such as methacrylate esters, improving the glass transition temperature (Tg) of the polymer. The aromatic rings within or between polymers interact with each other (π-π stacking effect) to arrange the polymer in an orderly manner, which is thought to result in resistance to pattern collapse in a developer even during fine pattern formation. Furthermore, the presence of an aromatic ring directly bonded to the main chain provides excellent etching resistance during etching steps after fine pattern formation. On the other hand, the α-fluoro(or fluoroalkyl)sulfonate anion preferably has an electron-withdrawing carbonyl group at the β-position from the sulfo group, thereby ensuring sufficient acidity for deprotecting the acid labile groups in the acid labile group units. Conventional α,α-difluoroalkanesulfonate anion structures have excessively strong acid strength, which can excessively induce deprotection reactions of the acid labile units and result in poor lithography performance. The α-fluoro(or fluoroalkyl)sulfonate anion of the onium salt-type monomer of the present invention generates sulfonic acid with a lower acidity than the α,α-difluoroalkanesulfonate anion. Therefore, it is preferable to select, as the structure of the acid labile group unit to be copolymerized, one that has a tertiary ester or tertiary ether structure and exhibits a relatively low activation energy for the deprotection reaction, driven by the generation of an allyl cation or benzyl cation. When an acid labile group that generates a simple tertiary carbocation is used, it is preferably a tertiary ester or tertiary ether having a cyclic structure.In this way, by combining a unit that generates an acid with a relatively low acidity with an acid-labile unit that has a relatively low activation energy for the deprotection reaction, the deprotection reaction occurs smoothly only in the exposed area, preventing a decrease in resolution due to blurred acid diffusion while maintaining good sensitivity, and improving LWR and CDU. Therefore, the polymer of the present invention is particularly suitable as a material for a chemically amplified positive resist composition.

[0183] [Monomer-type photoacid generator] The present invention also provides a monomeric photoacid generator, which is made from the onium salt monomer described above.

[0184] [polymer] The polymer of the present invention contains a repeating unit (hereinafter also referred to as repeating unit A) derived from a monomeric photoacid generator made of an onium salt-type monomer represented by the above general formula (A). That is, the present invention provides a polymer that contains a repeating unit derived from the above-described monomeric photoacid generator.

[0185] It is preferable that the polymer further contains a repeating unit represented by the following general formula (a1) (hereinafter also referred to as repeating unit a1) and / or a repeating unit represented by the following general formula (a2) (hereinafter also referred to as repeating unit a2): [ka] (In the formula, a1 is an integer of 0 to 4. R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 11-, and the phenylene group or naphthylene group may be substituted with a hydroxy 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 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. X 2 is a single bond or *-C(=O)-O-. * indicates a bond to a carbon atom in the main chain. R 21 is a halogen atom, a cyano group, a hydroxy group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. 21 may be the same as or different from each other. AL 1 and AL 2 are each independently an acid labile group.

[0186] In the above general formulas (a1) and (a2), R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0187] In the above general formula (a1), X 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 11-, and the phenylene group or naphthylene group may be substituted with a hydroxy 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 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. * represents a bond to a carbon atom in the main chain.

[0188] In the general formula (a2) above, X 2 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 21 is a halogen atom, a cyano group, a hydroxy group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. a1 is an integer of 0 to 4, preferably 0 or 1. When a1 is 2 or more, each R 21 may be the same as or different from each other.

[0189] In the above general formulae (a1) and (a2), AL 1 and AL 2 are each independently an acid labile group. Specific examples of the acid labile group include those described in JP-A Nos. 2013-080033 and 2013-083821.

[0190] Typical examples of the acid labile group include those represented by the following general formulae (AL-1) to (AL-3). [ka] (In the formula, * represents a bond.)

[0191] In the above general formulas (AL-1) and (AL-2), R L1 and R L2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group preferably has 1 to 20 carbon atoms.

[0192] In the above general formula (AL-1), a2 is an integer of 0 to 10, and an integer of 1 to 5 is preferable.

[0193] In the above general formula (AL-2), R L3 and R L4 are each independently a hydrogen atom or 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. The hydrocarbyl group preferably has 1 to 20 carbon atoms. In addition, R L2 , R L3 and R L4 Any two of these may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom or the carbon atom and oxygen atom to which they are bonded. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0194] In the above general formula (AL-3), R L5 , R L6 and R L7 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group preferably has 1 to 20 carbon atoms. In addition, R L5 , R L6 and R L7Any two of these may be bonded to each other to form, together with the carbon atoms to which they are bonded, a ring having 3 to 20 carbon atoms. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0195] Other structures of acid labile groups include those described in paragraphs

[0064] to

[0068] of JP 2023-123222 A and those described in paragraphs

[0013] to

[0014] of Japanese Patent No. 7492842 A. These use the generation of conjugated olefins or acrylic acid ester derivatives after the acid elimination reaction as the driving force for the reaction.

[0196] Specific examples of the repeating unit a1 include, but are not limited to, the following: A and AL 1 is the same as above.

[0197] [ka]

[0198] [ka]

[0199] [ka]

[0200] [ka]

[0201] Specific examples of the repeating unit a2 include, but are not limited to, the following: A and AL 2 is the same as above.

[0202] [ka]

[0203] [ka]

[0204] [ka]

[0205] The polymer may contain a repeating unit represented by the following general formula (a3) ​​(hereinafter also referred to as repeating unit a3). [ka] (In the formula, b1 is 0 or 1. When b1 is 0, b2 is an integer of 0 to 3, and when b1 is 1, b2 is an integer of 0 to 5. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 3 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. X 4 is 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 are each independently an oxygen atom or a sulfur atom, provided that X 4 and X 6 are attached to adjacent carbon atoms of the aromatic ring. R 22 and R 23 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 22 and R 23 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 24is a halogen atom, a hydroxy group, a cyano group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, or —N(R 24A )(R 24B ) is R 24A and R 24B are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms. When b2 is 2 or more, each R 24 may be the same or different, and multiple R 24 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached.)

[0206] In the above general formula (a3), b1 is 0 or 1. When b1 is 0, it is a benzene ring, and when b1 is 1, it is a naphthalene ring, but from the viewpoint of solvent solubility, b1 is preferably a benzene ring of 0. When b1 is 0, b2 is an integer of 0 to 3, and when b1 is 1, it is an integer of 0 to 5. From the viewpoint of raw material procurement, b2 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2.

[0207] In the above general formula (a3), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Among these, a hydrogen atom or a methyl group is preferred, and a hydrogen atom is more preferred.

[0208] In the general formula (a3), X 3 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. Among these, a single bond or *-C(=O)-O- is preferred, and a single bond is more preferred.

[0209] In the general formula (a3), X 4is 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. Of these, a single bond, a carbonyl group, or a sulfonyl group is preferred from the viewpoint of raw material procurement, and a single bond or a carbonyl group is more preferred from the viewpoint of the polar group generated after the reaction.

[0210] In the general formula (a3), X 5 and X 6 are each independently an oxygen atom or a sulfur atom, provided that X 4 and X 6 are attached to adjacent carbon atoms of the aromatic ring. 5 and X 6 may be the same or different from each other, but from the viewpoint of reactivity, X 5 and X 6 and are preferably both oxygen atoms.

[0211] In the above general formula (a3), R 22 and R 23are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms 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 icosyl; cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclopropyl, and methylcyclopropylmethyl. Examples of the alkyl group include saturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as a hexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group; alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, a 1-propenyl group, a 2-propenyl group, a butenyl group, and a hexenyl group; unsaturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclohexenyl group; aryl groups having 6 to 20 carbon atoms, such as a phenyl group and a naphthyl group; aralkyl groups having 7 to 20 carbon atoms, such as a benzyl group, a 1-phenylethyl group, and a 2-phenylethyl group; and groups obtained by combining these groups. 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, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group 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 sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0212] Also, R 22 and R 23may 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 in this case include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, and an adamantane ring. 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 -CH- groups in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the ring containing 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 sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0213] In the above general formula (a3), R 24 is a halogen atom, a hydroxy group, a cyano group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, or —N(R 24A )(R 24B ) is R 24A and R 24B are each 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 group and the hydrocarbyl moiety of the hydrocarbyloxy group, hydrocarbyloxycarbonyl group, and hydrocarbylthio group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 22 and R 23Examples of the hydrocarbyl group include the same as those exemplified above. In addition, 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, or a 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, a sulfur atom, or a nitrogen atom, and as a result, the hydrocarbyl group 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 sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like. When b2 is 2 or more, each R 24 may be the same as or different from each other.

[0214] Also, when b2 is 2 or more, multiple R 24 may be bonded to 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 a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, and an adamantane ring. 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 -CH- groups in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the ring containing 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 sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0215] That is, it is preferable that the polymer further contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following general formula (a1), a repeating unit represented by the following general formula (a2), and a repeating unit represented by the following general formula (a3).

[0216] Specific examples of the repeating unit a3 include, but are not limited to, the following: A is the same as above, and Me is a methyl group. The bonding positions of the various substituents on the aromatic ring may be interchanged.

[0217] [ka]

[0218] [ka]

[0219] [ka]

[0220] [ka]

[0221] [ka]

[0222] [ka]

[0223] [ka]

[0224] [ka]

[0225] [ka]

[0226]

change

[0227]

change

[0228]

change

[0229]

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[0230]

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[0231]

change

[0232]

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[0233]

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[0234]

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[0235]

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[0236]

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[0237]

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[0238]

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[0239]

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[0240]

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[0241]

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[0242]

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[0243]

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[0244]

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[0245]

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[0246]

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[0247]

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[0248]

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[0249]

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[0250]

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[0251]

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[0252]

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[0253]

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[0254]

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[0255]

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[0256]

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[0257]

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[0258] [ka]

[0259] [ka]

[0260] [ka]

[0261] [ka]

[0262] [ka]

[0263] [ka]

[0264] [ka]

[0265] [ka]

[0266] [ka]

[0267] It is preferable that the polymer further contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following general formula (b1) (hereinafter also referred to as repeating unit b1) and a repeating unit represented by the following general formula (b2) (hereinafter also referred to as repeating unit b2): [ka] (In the formula, c1 is an integer of 1 to 4, and c2 is an integer of 0 to 4, provided that 1≦c1+c2≦5. R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 31 is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-). R 32 is a halogen atom, a carboxy group, a nitro group, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. 32 may be the same as or different from each other.)

[0268] In the above general formulas (b1) and (b2), R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 31R is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-). 32 is a halogen atom, a carboxy group, a nitro group, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. c1 is an integer of 1 to 4. c2 is an integer of 0 to 4, with the proviso that 1≦c1+c2≦5. When c2 is 2 or more, each R 32 may be the same as or different from each other.

[0269] Specific examples of the repeating unit b1 include, but are not limited to, the following: A is the same as above.

[0270] [ka]

[0271] [ka]

[0272] [ka]

[0273] [ka]

[0274]

change

[0275]

change

[0276]

change

[0277]

change

[0278]

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[0279]

change

[0280]

change

[0281]

change

[0282]

change

[0283]

change

[0284]

change

[0285] [ka]

[0286] Specific examples of the repeating unit b2 include, but are not limited to, those shown below. A is the same as above, and Me is a methyl group.

[0287] [ka]

[0288] [ka]

[0289] [ka]

[0290] [ka]

[0291] [ka]

[0292] [ka]

[0293] As the repeating unit b1 or b2, those having a lactone ring as a polar group are particularly preferred in ArF lithography, and those having a phenol moiety are preferred in KrF lithography, EB lithography and EUV lithography.

[0294] The polymer may contain a repeating unit having a structure in which a hydroxy group is protected by an acid labile group (hereinafter also referred to as repeating unit c). The repeating unit c is not particularly limited as long as it has one or more structures in which a hydroxy group is protected and the protecting group is decomposed by the action of an acid to generate a hydroxy group, but is preferably one represented by the following general formula (c1): [ka]

[0295] In the above general formula (c1), R A is the same as above. R 41 R is a (d+1)-valent hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom. 42 is an acid labile group. d is an integer of 1 to 4.

[0296] In the above general formula (c1), R 42 The acid labile group represented by R may be any group that can be deprotected by the action of an acid to generate a hydroxy group. 42 Although the structure is not particularly limited, an acetal structure, a ketal structure, an alkoxycarbonyl group, or an alkoxymethyl group represented by the following general formula (c2) is preferred, and an alkoxymethyl group represented by the following general formula (c2) is particularly preferred. [ka] (In the formula, * represents a bond. R 43 is a hydrocarbyl group having 1 to 15 carbon atoms.

[0297] R 42 Specific examples of the acid labile group represented by the formula (c2), the alkoxymethyl group represented by the general formula (c2), and the repeating unit c are the same as those exemplified in the description of the repeating unit c described in JP 2020-111564 A.

[0298] The polymer may contain a repeating unit d derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or a derivative thereof. Specific examples of the monomer that gives the repeating unit d include, but are not limited to, those shown below. [Chemical formula]

[0299] The polymer may further contain a repeating unit e derived from indane, vinyl pyridine, or vinyl carbazole.

[0300] 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, 0 < A + a1 + a2 + a3 + b1 + b2 + c + d + e ≤ 1.0.

[0301] The weight average molecular weight (Mw) of the polymer is preferably 1,000 to 500,000, and more preferably 3,000 to 100,000. If Mw is within this range, sufficient etching resistance can be obtained, and there is no risk of deterioration of 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 THF or N,N-dimethylformamide (DMF) as a solvent.

[0302] Furthermore, since the influence of Mw / Mn on the molecular weight distribution of the polymer tends to become greater as the pattern rule becomes finer, in order to obtain a resist composition that is suitable for use with fine pattern dimensions, it is preferable that Mw / Mn be a narrow distribution of 1.0 to 2.0. If the Mw / Mn is within the above range, there will be fewer polymers with low or high molecular weights compared to Mw, and there will be no risk of foreign matter being observed on the pattern or the pattern shape being deteriorated after exposure.

[0303] To synthesize the polymer, for example, a monomer that provides the repeating unit described above may be polymerized by heating in an organic solvent with the addition of a radical polymerization initiator.

[0304] 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 the polymerization initiator 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% based on 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.

[0305] The polymerization initiator may be added to the monomer solution and then fed to the reaction vessel. Alternatively, an initiator solution may be prepared separately from the monomer solution and then fed to the reaction vessel independently. Because radicals generated from the initiator during the waiting time may cause the polymerization reaction to proceed, resulting in the formation of ultra-high molecular weight polymers, and from the standpoint of quality control, it is preferable to prepare the monomer solution and the initiator solution independently and then add them dropwise. The acid labile group introduced into the monomer may be used as is, or may be protected or partially protected after polymerization. Furthermore, known chain transfer agents such as dodecyl mercaptan and 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.

[0306] In the case of a monomer containing a hydroxy group, the hydroxy group may be substituted with an acetal group, such as an ethoxyethoxy group, which is easily deprotected by an acid, during polymerization, and then deprotected with a weak acid and water after polymerization. Alternatively, the hydroxy group may be substituted with an acetyl group, a formyl group, a pivaloyl group, or the like, and then subjected to alkaline hydrolysis after polymerization.

[0307] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, hydroxystyrene or hydroxyvinylnaphthalene and other monomers may be polymerized by heating in an organic solvent with the addition of a radical polymerization initiator. Alternatively, acetoxystyrene or acetoxyvinylnaphthalene may be used, and after polymerization, the acetoxy group may be deprotected by alkaline hydrolysis to form polyhydroxystyrene or hydroxypolyvinylnaphthalene.

[0308] The base that can be used in alkaline hydrolysis includes aqueous ammonia, triethylamine, etc. 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.

[0309] The amount of each monomer in the monomer solution may be appropriately set so as to achieve the preferred content ratio of the repeating units described above.

[0310] The polymer obtained by the above-described production method may be a reaction solution obtained by a polymerization reaction as a final product, or a powder obtained through a purification step such as a reprecipitation method in which the reaction solution is added to a poor solvent to obtain a powder, and the resulting powder may be handled as a final product. However, from the viewpoint of work efficiency and quality stability, it is preferable to handle a polymer solution obtained by dissolving the powder obtained through the purification step in a solvent as a final product.

[0311] Specific examples of the solvent used in this case include ketones such as cyclohexanone and methyl-2-n-pentyl ketone, as described in paragraphs

[0144] to

[0145] of JP-A 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. 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 mono tert-butyl ether acetate; lactones such as GBL; alcohols such as diacetone alcohol (DAA); high-boiling alcohol solvents such as diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, and 1,3-butanediol; and mixed solvents thereof.

[0312] The concentration of the polymer in the polymer solution is preferably 0.01 to 30% by mass, more preferably 0.1 to 20% by mass.

[0313] The reaction solution and polymer solution are preferably filtered through a filter, which is effective in stabilizing quality by removing foreign matter and gels that may cause defects.

[0314] Examples of filter materials used in the filter filtration include fluorocarbon, cellulose, nylon, polyester, and hydrocarbon-based materials. However, in the filtration process of resist compositions, filters made of fluorocarbons, such as Teflon (registered trademark), hydrocarbons such as polyethylene and polypropylene, or nylon are preferred. The pore size of the filter can be selected appropriately depending on the target cleanliness, but is preferably 100 nm or less, more preferably 20 nm or less. These filters may be used alone or in combination. The filtration method may involve passing the solution through the filter only once, but it is more preferable to circulate the solution and filter it multiple times. The filtration process can be performed in any order and any number of times in the polymer production process. However, it is preferable to filter the reaction solution after the polymerization reaction, the polymer solution, or both.

[0315] [Chemically amplified resist composition] The present invention also provides a chemically amplified resist composition, which comprises (A) a base polymer containing the above-described polymer.

[0316] [(A) Base polymer] The chemically amplified resist composition of the present invention contains, as component (A), a base polymer containing the above-mentioned polymer.

[0317] The polymers may be used singly or in combination of two or more with different composition ratios, Mw, and / or Mw / Mn. In addition to the polymers described above, the base polymer (A) may contain a hydrogenated ring-opening metathesis polymer, and those described in JP-A-2003-066612 can be used.

[0318] In this case, it is preferable that the chemically amplified resist composition further contains one or more selected from the group consisting of (B) an organic solvent, (C) a quencher, (D) a photoacid generator other than the monomeric photoacid generator, and (E) a surfactant. Each component will be described in detail below.

[0319] [(B) Organic solvent] 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 below. 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; ketoalcohols 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 mono-tert-butyl ether acetate; lactones such as GBL; and mixed solvents thereof.

[0320] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, cyclohexanone, GBL, ethyl lactate, DAA, and mixed solvents thereof are preferred, as they have particularly excellent solubility for the base polymer of component (A).

[0321] In the chemically amplified resist composition of the present invention, the content of (B) organic solvent is preferably 200 to 7,000 parts by mass, more preferably 400 to 5,000 parts by mass, relative to 80 parts by mass of (A) base polymer. (B) The organic solvent may be used alone or in combination of two or more.

[0322] [(C) Quencher] The chemically amplified resist composition of the present invention may contain a quencher as component (C). In the present invention, the quencher is a material that traps the acid generated by the photoacid generator in the chemically amplified resist composition, thereby preventing it from diffusing to unexposed areas and forming a desired pattern.

[0323] Specific examples of the (C) quencher include onium salts represented by the following general formula (1) or (2). [ka]

[0324] In the above general formula (1), R q1 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain 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. q2 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom.

[0325] R q1Specific examples of the hydrocarbyl group having 1 to 40 carbon atoms represented by the formula (I) include alkyl groups having 1 to 40 carbon atoms 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]. 2,6 cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as a decyl group or an adamantyl group; and aryl groups having 6 to 40 carbon atoms, such as a phenyl group, a naphthyl group or an anthracenyl group. Some or all of the hydrogen atoms in the hydrocarbyl groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms or halogen atoms, and some of the -CH2- groups in the hydrocarbyl groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms or nitrogen atoms, so that the hydrocarbyl groups may contain hydroxy groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonate ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc.

[0326] R q2 Specific examples of the hydrocarbyl group represented by R q1 In addition to the substituents exemplified as specific examples, examples include fluorinated saturated hydrocarbyl groups such as trifluoromethyl group and trifluoroethyl group, and fluorinated aryl groups such as pentafluorophenyl group and 4-trifluoromethylphenyl group.

[0327] Specific examples of the anion of the onium salt represented by the above general formula (1) include, but are not limited to, those shown below.

[0328] [ka]

[0329] [ka]

[0330] [ka]

[0331] [ka]

[0332] [ka]

[0333] Specific examples of the anion of the onium salt represented by the above general formula (2) include, but are not limited to, those shown below.

[0334] [ka]

[0335] [ka]

[0336] [ka]

[0337] [ka]

[0338] [ka]

[0339] In the above general formulas (1) and (2), Mq + is an onium cation. Examples of the onium cation include a sulfonium cation, an iodonium cation, and an ammonium cation. Specific examples of the sulfonium cation include, but are not limited to, those exemplified as specific examples of the sulfonium cation in general formula (A) above.

[0340] Specific examples of the iodonium cation include those exemplified as specific examples of the iodonium cation in the general formula (A) above, but are not limited to these.

[0341] Specific examples of the ammonium cation include those represented by the following general formula (am-1). [ka]

[0342] In the above general formula (am-1), R q21 ~R q24 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. q21 and R q22 However, they may be bonded to each other to form a ring together with the nitrogen atom to which they are bonded. Specific examples of the hydrocarbyl group include those represented by R 1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0343] Specific examples of the ammonium cation represented by the above general formula (am-1) include, but are not limited to, those shown below.

[0344] [ka]

[0345] Specific examples of the onium salts represented by the general formula (1) or (2) include any combination of the anions and cations described above. These onium salts can be easily prepared by ion exchange reactions using known organic chemical methods. For details on ion exchange reactions, see, for example, JP 2007-145797 A.

[0346] The onium salts represented by the general formula (1) or (2) function as quenchers in the chemically amplified resist composition of the present invention. This is because the counter anions of the onium salts are the conjugate bases of weak acids. The term "weak acid" as used herein refers to an acidity that is insufficient to deprotect the acid labile groups of the acid labile group-containing units used in the base polymer. The onium salts represented by the general formula (1) or (2) function as quenchers when used in combination with an onium salt-type photoacid generator having a counter anion that is the conjugate base of a strong acid, such as a sulfonic acid fluorinated at the α-position. Specifically, when an onium salt that generates a strong acid, such as a sulfonic acid fluorinated at the α-position, is mixed with an onium salt that generates a weak acid, such as a non-fluorinated sulfonic acid or carboxylic acid, the strong acid generated from the photoacid generator upon irradiation with high-energy radiation collides with an onium salt having an unreacted weak acid anion, releasing the weak acid through salt exchange and generating an onium salt having a strong acid anion. In this process, the strong acid is exchanged for a weak acid with a lower catalytic activity, and the acid appears to be deactivated, allowing for control of acid diffusion.

[0347] Furthermore, as the (C) quencher, onium salts having a sulfonium cation and a phenoxide anion moiety in the same molecule as described in Japanese Patent No. 6848776, onium salts having a sulfonium cation and a carboxylate anion moiety in the same molecule as described in Japanese Patent No. 6583136 and JP-A-2020-200311, and onium salts having an iodonium cation and a carboxylate anion moiety in the same molecule as described in Japanese Patent No. 6274755 can also be used.

[0348] Here, when the photoacid generator that generates a strong acid is an onium salt, the strong acid generated by irradiation with high-energy rays can be exchanged for a weak acid as described above, but on the other hand, it is thought that the weak acid generated by irradiation with high-energy rays collides with the unreacted onium salt that generates the strong acid, making it difficult to carry out salt exchange. This is due to the phenomenon that the onium cation is more likely to form an ion pair with the anion of the strong acid.

[0349] When the chemically amplified resist composition of the present invention contains an onium salt represented by the general formula (1) or (2) as the quencher (C), the content thereof is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, relative to 80 parts by mass of the base polymer (A). A content of the onium salt quencher of component (C) within the above range is preferred because it provides good resolution and does not significantly reduce sensitivity. The onium salt represented by the general formula (1) or (2) may be used alone or in combination of two or more.

[0350] The chemically amplified resist composition of the present invention may contain a nitrogen-containing compound as a quencher (C). Specific examples of the nitrogen-containing compound (C) include primary, secondary, or tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP 2008-111103 A, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonate ester bond. Further examples include compounds in which a primary or secondary amine is protected with a carbamate group, as described in JP 3790649 A.

[0351] Alternatively, a sulfonate sulfonium 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 by neutralizing with the acid generated by the compound itself, functioning as a so-called photodegradable base. The use of a photodegradable base can further enhance the contrast between the exposed and unexposed areas. For example, JP-A Nos. 2009-109595 and 2012-046501 can be used as references for the photodegradable base.

[0352] When the chemically amplified resist composition of the present invention contains a nitrogen-containing compound as a quencher (C), the content thereof is preferably 0.001 to 12 parts by mass, more preferably 0.01 to 8 parts by mass, relative to 80 parts by mass of the base polymer (A). The nitrogen-containing compound may be used alone or in combination of two or more types.

[0353] [(D) Other photoacid generators] The chemically amplified resist composition of the present invention may contain, as component (D), a photoacid generator other than the above-described monomeric photoacid generator (hereinafter also referred to as "other photoacid generator"). The other photoacid generator is not particularly limited as long as it is a compound that generates an acid upon exposure to high-energy rays. Suitable (D) other photoacid generators include those represented by the following general formula (3) or (4): [ka]

[0354] In the above general formula (3), R 101 ~R 105 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 101 , R 102 and R 103 Any two of may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0355] Specific examples of the sulfonium cation of the sulfonium salt represented by the general formula (3) include, but are not limited to, those exemplified as specific examples of the sulfonium cation in the general formula (A). Specific examples of the iodonium cation of the iodonium salt represented by the general formula (4) include, but are not limited to, those exemplified as specific examples of the iodonium cation in the general formula (A).

[0356] In the above general formulas (3) and (4), Xa -is an anion of a strong acid. Examples of the anion of a strong acid include those represented by any of the following general formulas (Xa-1) to (Xa-4). [ka]

[0357] In the above general formula (Xa-1), R fa 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. Specific examples thereof include R in the general formula (Xa-1-1) described below. fa1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0358] The anion represented by the above general formula (Xa-1) is preferably one represented by the following general formula (Xa-1-1). [ka]

[0359] In the above general formula (Xa-1-1), Q 1 and Q 2 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, but in order to improve solvent solubility, it is preferable that at least one of them is a trifluoromethyl group. m is an integer of 0 to 4, and is particularly preferably 1. R fa1 is a hydrocarbyl group having 1 to 35 carbon atoms which may contain a heteroatom. The heteroatom is preferably an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or the like, and more preferably an oxygen atom. From the viewpoint of obtaining high resolution in the formation of a fine pattern, the hydrocarbyl group is particularly preferably one having 6 to 30 carbon atoms.

[0360] In the above general formula (Xa-1-1), R fa1The hydrocarbyl group having 1 to 35 carbon atoms and represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 35 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, a nonyl group, an undecyl group, a tridecyl group, a pentadecyl group, a heptadecyl group, and an icosyl group; a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a 1-adamantylmethyl group, a norbornyl group, a norbornyl group, and an alkyl group having 1 to 35 carbon atoms. Examples of such alkyl groups include saturated cyclic hydrocarbyl groups having 3 to 35 carbon atoms, such as a 2-cyclohexylmethyl group, a tricyclodecyl group, a tetracyclododecyl group, a tetracyclododecylmethyl group, and a dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 35 carbon atoms, such as a 2-propenyl group and a 3-cyclohexenyl group; aryl groups having 6 to 35 carbon atoms, such as a phenyl group, a 1-naphthyl group, a 2-naphthyl group, and a 9-fluorenyl group; aralkyl groups having 7 to 35 carbon atoms, such as a benzyl group and a diphenylmethyl group; and groups obtained by combining these groups.

[0361] 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, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group 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 sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. Specific examples of hydrocarbyl groups containing hetero atoms include tetrahydrofuryl, methoxymethyl, ethoxymethyl, methylthiomethyl, acetamidomethyl, trifluoroethyl, (2-methoxyethoxy)methyl, acetoxymethyl, 2-carboxy-1-cyclohexyl, 2-oxopropyl, 4-oxo-1-adamantyl, and 3-oxocyclohexyl groups.

[0362] In the above general formula (Xa-1-1), L a1 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, or a carbamate bond, but from the viewpoint of synthesis, an ether bond or an ester bond is preferred, and an ester bond is more preferred.

[0363] Specific examples of the anion represented by the general formula (Xa-1) include, but are not limited to, the following: 1 is the same as above, and Ac is an acetyl group.

[0364] [ka]

[0365] [ka]

[0366] [ka]

[0367] [ka]

[0368] [ka]

[0369] [ka]

[0370] [ka]

[0371] [ka]

[0372] [ka]

[0373] [ka]

[0374] In the above general formula (Xa-2), R fb1 and R fb2 are each independently 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. Specific examples thereof include R in the above general formula (Xa-1-1). fa1 Examples of the hydrocarbyl group represented by R include the same as those exemplified above. fb1 and R fb2 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 are bonded to each other and form the bonded group (-CF2-SO2-N - -SO2-CF2-) together may form a ring, in which case R fb1 and R fb2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0375] In the above general formula (Xa-3), R fc1 , R fc2 and R fc3 are each independently 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. Specific examples thereof include R in the above general formula (Xa-1-1). fa1Examples of the hydrocarbyl group represented by R include the same as those exemplified above. fc1 , R fc2 and R fc3 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 are bonded to each other and form the bonded group (-CF2-SO2-C - -SO2-CF2-) together may form a ring, in which case R fc1 and R fc2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0376] In the above general formula (Xa-4), R fd is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in the above general formula (Xa-1-1). fa1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0377] Specific examples of the anion represented by the above general formula (Xa-4) include, but are not limited to, those shown below.

[0378] [ka]

[0379] [ka]

[0380] Further examples of the anion of the strong acid include an anion having an aromatic ring substituted with an iodine atom or a bromine atom. Specific examples of such an anion include those represented by the following general formula (Xa-5): [ka]

[0381] In the above general formula (Xa-5), x is 1, 2, or 3. y is an integer of 1 to 5. z is an integer of 0 to 3, provided that 1≦y+z≦5. y is preferably 1, 2, or 3, and more preferably 2 or 3. z is preferably 0, 1, or 2.

[0382] In the above general formula (Xa-5), X BI is an iodine atom or a bromine atom, and when x and / or y are 2 or more, they may be the same or different.

[0383] In the above general formula (Xa-5), L 1 is a single bond, an ether bond, an ester bond, or a saturated hydrocarbylene group having 1 to 6 carbon atoms which may contain an ether bond or an ester bond. The saturated hydrocarbylene group may be linear, branched, or cyclic.

[0384] In the above general formula (Xa-5), L 2 represents a single bond or a divalent linking group having 1 to 20 carbon atoms when x is 1, and represents an (x+1)-valent linking group having 1 to 20 carbon atoms when x is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0385] In the above general formula (Xa-5), R fe is a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, or a hydrocarbyl group having 1 to 20 carbon atoms, a hydrocarbyloxy group having 1 to 20 carbon atoms, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, or a hydrocarbylsulfonyloxy group having 1 to 20 carbon atoms, which may contain a fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group, or an ether bond, or feA )(R feB ), -N(R feC )-C(=O)-R feD , or -N(R feC )-C(=O)-ORfeD R feA and R feB are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. feC is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may contain a halogen atom, a hydroxy 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 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 hydroxy 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 may be the same or different from each other.

[0386] Of these, R fe Examples of the hydroxyl group include -N(R feC )-C(=O)-R feD , -N(R feC )-C(=O)-OR feD fluorine atom, chlorine atom, bromine atom, methyl group, methoxy group, etc. are preferred.

[0387] In the above general formula (Xa-5), Rf 11 ~Rf 14 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of them is a fluorine atom or a trifluoromethyl group. 11 and Rf 12 may combine to form a carbonyl group.13 and Rf 14 are preferably both fluorine atoms.

[0388] Specific examples of the anion represented by the general formula (Xa-5) include, but are not limited to, the following: BI is the same as above.

[0389] [ka]

[0390] [ka]

[0391] [ka]

[0392] [ka]

[0393] [ka]

[0394] [ka]

[0395] [ka]

[0396] [ka]

[0397] [ka]

[0398]

change

[0399]

change

[0400]

change

[0401]

change

[0402]

change

[0403]

change

[0404]

change

[0405]

change

[0406]

change

[0407]

change

[0408] [ka]

[0409] [ka]

[0410] [ka]

[0411] [ka]

[0412] Examples of the anion of the strong acid include a fluorobenzenesulfonate anion bonded to an aromatic group containing an iodine atom, as described in Japanese Patent No. 6648726, an anion having a mechanism of decomposition by acid, as described in International Publication No. 2021 / 200056 and Japanese Patent Application Publication No. 2021-070692, an anion having a cyclic ether group, as described in Japanese Patent Application Publication No. 2018-180525 and Japanese Patent Application Publication No. 2021-035935, and an anion described in Japanese Patent Application Publication No. 2018-092159.

[0413] Further examples of the strong acid anion include anions of bulky benzenesulfonic acid derivatives that do not contain fluorine atoms, as described in JP 2006-276759 A, JP 2015-117200 A, JP 2016-065016 A, and JP 2019-202974 A, and benzenesulfonic acid anions and alkylsulfonic acid anions that do not contain fluorine atoms bonded to aromatic groups containing iodine atoms, as described in Japanese Patent No. 6645464 A.

[0414] Further examples of the strong acid anion include the anion of a bissulfonic acid described in JP 2015-206932 A, the anion of a sulfonamide or sulfonimide described in WO 2020 / 158366 A, which has a sulfonic acid on one side and a different sulfonamide or sulfonimide on the other side, and the anion of a sulfonic acid on one side and a carboxylic acid on the other side described in JP 2015-024989 A.

[0415] Furthermore, as the other photoacid generator of component (D), compounds represented by the following general formula (5) are also preferred. [ka]

[0416] In the above general formula (5), R 201 and R 202 R are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. 203 is a hydrocarbylene group having 1 to 30 carbon atoms which may contain a heteroatom. 201 , R 202 and R 203 Any two of may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0417] R 201 and R 202 The hydrocarbyl group having 1 to 30 carbon atoms represented by the formula (I) 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 a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a tert-pentyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, an oxanorbornyl group, and a tricyclo[5.2.1.0] 2,6cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as a decyl group and an adamantyl group; aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a methylphenyl group, an ethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, an n-butylphenyl group, an isobutylphenyl group, a sec-butylphenyl group, a tert-butylphenyl group, a naphthyl group, a methylnaphthyl group, an ethylnaphthyl group, an n-propylnaphthyl group, an isopropylnaphthyl group, an n-butylnaphthyl group, an isobutylnaphthyl group, a sec-butylnaphthyl group, a tert-butylnaphthyl group and an anthracenyl group; and groups obtained by combining these groups. 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, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group 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 sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0418] R 203The hydrocarbylene group having 1 to 30 carbon atoms represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkanediyl groups having 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, and heptadecane-1,17-diyl group; Examples of the alkylene groups include cyclic saturated hydrocarbylene groups having 3 to 30 carbon atoms, such as a cyclohexanediyl group, a norbornanediyl group, a cyclohexanediyl group, a norbornanediyl group, and an adamantanediyl group; and arylene groups, such as a phenylene group, a methylphenylene group, an ethylphenylene group, an n-propylphenylene group, an isopropylphenylene group, an n-butylphenylene group, an isobutylphenylene group, a sec-butylphenylene group, a tert-butylphenylene group, a naphthylene group, a methylnaphthylene group, an ethylnaphthylene group, an n-propylnaphthylene group, an isopropylnaphthylene group, an n-butylnaphthylene group, an isobutylnaphthylene group, a sec-butylnaphthylene group, and a tert-butylnaphthylene group. In addition, 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, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH- groups of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the hydrocarbylene group containing 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 sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. As the heteroatom, an oxygen atom is preferred.

[0419] In the above general formula (5), L 11is a single bond, an ether bond, or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 203 Examples of the hydrocarbylene group represented by the formula (I) include the same as those exemplified above.

[0420] In the above general formula (5), X a , X b , X c , and X d are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that X a , X b , X c , and X d At least one of the groups is a fluorine atom or a trifluoromethyl group.

[0421] The photoacid generator represented by the above general formula (5) is preferably one represented by the following general formula (5'). [ka]

[0422] In the above general formula (5'), L 11 is the same as above. X e is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. 301 , R 302 and R 303 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in the above general formula (Xa-1-1). fa1 Examples of the hydrocarbyl group include the same as those exemplified above. Each of s and t is independently an integer of 0 to 5, and u is an integer of 0 to 4.

[0423] Examples of the photoacid generator represented by the general formula (5) include the same compounds as those exemplified as the photoacid generator represented by formula (2) in JP-A-2017-026980.

[0424] Among the other photoacid generators, those containing anions represented by the general formula (Xa-1-1) or (Xa-4) are particularly preferred because of their small acid diffusion and excellent solubility in solvents. Furthermore, those represented by the general formula (5') are particularly preferred because of their extremely small acid diffusion.

[0425] When the chemically amplified resist composition of the present invention contains (D) other photoacid generator, the content thereof is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 20 parts by mass, per 80 parts by mass of the (A) base polymer. When the amount of the (D) other photoacid generator is within the above range, the resolution is good and there is no risk of problems with foreign matter occurring after development of the resist film or during stripping, which is preferable. The (D) other photoacid generators may be used alone or in combination of two or more.

[0426] [(E) Surfactant] The chemically amplified resist composition of the present invention may further comprise a surfactant as component (E). The surfactant (E) is preferably a surfactant that is insoluble or slightly soluble in water but soluble in an alkaline developer, or a surfactant that is insoluble or slightly soluble in both water and an alkaline developer. Examples of such surfactants include those described in JP-A-2010-215608 and JP-A-2011-016746.

[0427] Among the surfactants described in the above publications, preferred surfactants that are insoluble or slightly soluble in water and alkaline developers include FC-4430 (manufactured by 3M), Surflon (registered trademark) S-381 (manufactured by AGC Seimi Chemical Co., Ltd.), Olfine (registered trademark) E1004 (manufactured by Nissin Chemical Industry Co., Ltd.), KH-20, KH-30 (manufactured by AGC Seimi Chemical Co., Ltd.), and oxetane ring-opening polymers represented by the following general formula (surf-1): [ka]

[0428] Here, R, Rf, A, B, C, m, and n apply only to the above general formula (surf-1), regardless of the above descriptions. R is a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Examples of the divalent aliphatic group include an ethylene group, a 1,4-butylene group, a 1,2-propylene group, a 2,2-dimethyl-1,3-propylene group, and a 1,5-pentylene group, and examples of the trivalent or tetravalent aliphatic group include the following: [ka] (In the formula, the dashed lines represent bonds and are partial structures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.)

[0429] Among these, a 1,4-butylene group, a 2,2-dimethyl-1,3-propylene group, and the like are preferred.

[0430] Rf is a trifluoromethyl group or a pentafluoroethyl group, preferably a trifluoromethyl group. m is an integer of 0 to 3, n is an integer of 1 to 4, and the sum of n and m is the valence of R, which is an integer of 2 to 4. A is 1. B is an integer of 2 to 25, preferably an integer of 4 to 20. C is an integer of 0 to 10, preferably 0 or 1. The order of the structural units in the general formula (surf-1) is not specified, and they may be bonded in blocks or randomly. The production of partially fluorinated oxetane ring-opening polymer surfactants is described in detail in the specification of U.S. Pat. No. 5,650,483, etc.

[0431] Surfactants that are insoluble or slightly soluble in water but 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 for suppressing the elution of water-soluble components from the resist film and reducing damage to the exposure equipment. They are also useful because they become soluble during alkaline aqueous development after exposure or post-exposure bake (PEB), making them less likely to become contaminants that cause defects. Such surfactants are insoluble or slightly soluble in water but soluble in alkaline developers. They are polymeric surfactants, also known as hydrophobic resins, and are particularly preferred because they have high water repellency and improve water slippage.

[0432] Specific examples of such polymer surfactants include those containing at least one repeating unit selected from those represented by any of the following general formulae (6A) to (6E). [ka]

[0433] In the above general formulas (6A) to (6E), R B is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is -CH2-, -CH2CH2-, -O-, or two -H groups separated from each other. s1 are each 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 R are each independently a hydrogen atom, a hydrocarbyl group or a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group. s3 When R is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. s4 is a hydrocarbon group or a fluorinated hydrocarbon group having 1 to 20 carbon atoms and a valence of (w+1). w is 1, 2, or 3. R s5are each independently a hydrogen atom or -C(=O)-OR sa R is a group represented by sa is a fluorinated hydrocarbyl group having 1 to 20 carbon atoms. s6 is a hydrocarbyl group or a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, and an ether bond or a carbonyl group may be present between the carbon-carbon bonds.

[0434] R s1 The hydrocarbyl group having 1 to 10 carbon atoms represented by the formula (I) is preferably a saturated hydrocarbyl group, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms, 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; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl. Of these, those having 1 to 6 carbon atoms are preferred.

[0435] R s2 The hydrocarbylene group represented by the formula (I) is preferably a saturated hydrocarbylene group, which may be linear, branched, or cyclic. Specific examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, and a pentylene group.

[0436] R s3 or R s6 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include saturated hydrocarbyl groups, and aliphatic unsaturated hydrocarbyl groups such as alkenyl groups and alkynyl groups, with saturated hydrocarbyl groups being preferred. As the saturated hydrocarbyl group, R s1 In addition to the examples of the hydrocarbyl group represented by the formula (R), examples include an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, and a pentadecyl group. s3 or R s6Examples of the fluorinated hydrocarbyl group represented by the formula (I) include groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the aforementioned hydrocarbyl group have been substituted with fluorine atoms. As mentioned above, an ether bond or a carbonyl group may be present between these carbon-carbon bonds.

[0437] R s3 Specific examples of the acid labile group represented by the formula (AL-1) to (AL-3) above include groups represented by the formula (AL-1) to (AL-3), trialkylsilyl groups in which each alkyl group has 1 to 6 carbon atoms, and oxo group-containing alkyl groups having 4 to 20 carbon atoms.

[0438] R s4 The (w+1)-valent hydrocarbon group or fluorinated hydrocarbon group represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include groups obtained by further eliminating w hydrogen atoms from the aforementioned hydrocarbyl group or fluorinated hydrocarbyl group.

[0439] R sa The fluorinated hydrocarbyl group represented by the formula (I) is preferably saturated and may be linear, branched or cyclic. Specific examples thereof include those in which some or all of the hydrogen atoms of the hydrocarbyl groups have been substituted with fluorine atoms, and specific examples thereof include a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a 3,3,3-trifluoro-1-propyl group, a 3,3,3-trifluoro-2-propyl group, a 2,2,3,3-tetrafluoropropyl group, a 1,1,1,3,3,3-hexafluoroisopropyl group, a 2,2,3,3,4,4,4-heptafluorobutyl group, a 2,2,3,3,4,4,5,5-octafluoropentyl group, a 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl group, a 2-(perfluorobutyl)ethyl group, a 2-(perfluorohexyl)ethyl group, a 2-(perfluorooctyl)ethyl group, and a 2-(perfluorodecyl)ethyl group.

[0440] Specific examples of the repeating unit represented by any one of the general formulae (6A) to (6E) include, but are not limited to, the following: B is the same as above.

[0441] [ka]

[0442] [ka]

[0443] [ka]

[0444] [ka]

[0445] [ka]

[0446] [ka]

[0447] The polymer surfactant may further contain other repeating units in addition to the repeating units represented by the general formulae (6A) to (6E). Examples of such other repeating units include repeating units obtained from methacrylic acid and α-trifluoromethylacrylic acid derivatives. In the polymer surfactant, the content of the repeating units represented by the general formulae (6A) to (6E) is preferably 20 mol % or more, more preferably 60 mol % or more, and even more preferably 100 mol %, of all repeating units.

[0448] The Mw of the polymer surfactant is preferably from 1,000 to 500,000, and more preferably from 3,000 to 100,000. The Mw / Mn is preferably from 1.0 to 2.0, and more preferably from 1.0 to 1.6.

[0449] The polymer surfactant can be synthesized by heating a monomer containing an unsaturated bond that provides the repeating units represented by the general formulae (6A) to (6E) and, if necessary, other repeating units in an organic solvent with the addition of a radical initiator to polymerize the monomer. Examples of organic solvents used in polymerization include toluene, benzene, THF, diethyl ether, and dioxane. 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 labile group introduced into the monomer may be used as is, or may be protected or partially protected after polymerization.

[0450] When synthesizing the polymeric surfactant, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol may be used to adjust the molecular weight. In this case, the amount of the chain transfer agent added is preferably 0.01 to 10 mol % based on the total number of moles of the monomers to be polymerized.

[0451] When the chemically amplified resist composition of the present invention contains a surfactant (E), the content thereof is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 10 parts by mass, per 80 parts by mass of the base polymer (A). When the surfactant (E) content is 0.1 part by mass or more, the receding contact angle between the resist film surface and water is sufficiently improved, while when the surfactant content is 50 parts by mass or less, the dissolution rate of the resist film surface in the developer is low, and the height of the formed fine pattern is sufficiently maintained. The surfactant (E) may be used alone or in combination of two or more types.

[0452] [(F) Other ingredients] The chemically amplified resist composition of the present invention may contain, as other components (F), a compound that decomposes in the presence of acid to generate acid (acid amplifying compound), an organic acid derivative, a fluorine-substituted alcohol, or a compound with a Mw of 3,000 or less whose solubility in a developer changes upon the action of acid (dissolution inhibitor). Examples of the acid amplifying compound include the compounds described in JP-A-2009-269953 and JP-A-2010-215608. When the acid amplifying compound is contained, its content is preferably 0 to 5 parts by weight, more preferably 0 to 3 parts by weight, per 80 parts by weight of the (A) base polymer. A content within this range allows for control of acid diffusion, and degradation of resolution and pattern shape is unlikely to occur. Examples of the organic acid derivative, fluorine-substituted alcohol, and dissolution inhibitor include the compounds described in JP-A-2009-269953 and JP-A-2010-215608.

[0453] [Pattern formation method] The present invention also provides a pattern formation method, which includes the steps of forming a resist film on a substrate using the chemically amplified resist composition described above, exposing the resist film to high-energy rays, and developing the exposed resist film using a developer.

[0454] The substrate may be, for example, a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coating, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.).

[0455] The resist film can be formed, for example, by applying the chemically amplified resist composition onto a substrate by a method such as spin coating so that the film thickness is preferably 0.05 to 2 μm, and then pre-baking the composition on a hot plate preferably at 60 to 150°C for 1 to 10 minutes, more preferably at 80 to 140°C for 1 to 5 minutes.

[0456] Examples of high-energy rays used to expose the resist film include KrF excimer laser light, ArF excimer laser light, electron beam (EB), and extreme ultraviolet light (EUV) with a wavelength of 3 to 15 nm. When KrF excimer laser light, ArF excimer laser light, or EUV is used for exposure, a mask for forming a desired pattern is used, and the exposure dose is preferably 1 to 200 mJ / cm. 2 , more preferably 10 to 100 mJ / cm 2 When EB is used, the exposure dose is preferably 1 to 300 μC / cm 2 , either directly or through a mask for forming a desired pattern. 2 , more preferably 10 to 200 μC / cm 2 Irradiate so that

[0457] In addition to the usual exposure method, the immersion method can also be used, in which a liquid with a refractive index of 1.0 or higher is placed between the resist film and the projection lens. In this case, a water-insoluble protective film can also be used.

[0458] The water-insoluble protective film is used to prevent elution from the resist film and increase the water sliding property of the film surface. It can be broadly divided into two types. One is an organic solvent-removable type that requires stripping before alkaline aqueous development using an organic solvent that does not dissolve the resist film. The other is an alkaline aqueous solution-soluble type that is soluble in alkaline developer and removes the protective film along with removing the soluble portion of the resist film. The latter is particularly based on a polymer containing 1,1,1,3,3,3-hexafluoro-2-propanol residues that is insoluble in water but soluble in alkaline developer, and is preferably dissolved in an alcohol solvent with 4 or more carbon atoms, an ether solvent with 8 to 12 carbon atoms, or a mixed solvent thereof. Materials can also be prepared by dissolving the water-insoluble, alkaline developer-soluble surfactant described above in an alcohol solvent with 4 or more carbon atoms, an ether solvent with 8 to 12 carbon atoms, or a mixed solvent thereof.

[0459] After the exposure, PEB may be performed by heating on a hot plate, preferably at 60 to 150° C. for 1 to 5 minutes, more preferably at 80 to 140° C. for 1 to 3 minutes.

[0460] The development is carried out using a developer, for example, an alkaline aqueous solution of tetramethylammonium hydroxide (TMAH) or the like, preferably at 0.1 to 5 mass %, more preferably 2 to 3 mass %, for preferably 0.1 to 3 minutes, more preferably 0.5 to 2 minutes, by a conventional method such as dipping, puddling, or spraying, whereby the exposed areas are dissolved and the desired pattern is formed on the substrate.

[0461] After forming the resist film, the resist film may be rinsed with pure water to extract the acid generator and the like from the film surface or to wash away particles, or the resist film may be rinsed after exposure to remove water remaining on the film.

[0462] Furthermore, the pattern may be formed by a double patterning method, such as a trench method in which a first exposure and etching process is performed to process an underlayer with a 1:3 trench pattern, and then a second exposure process is performed with a shifted position to form a 1:3 trench pattern, thereby forming a 1:1 pattern, or a line method in which a first underlayer with a 1:3 isolated leave pattern is processed by a first exposure and etching process, and then a second exposure process is performed with a shifted position to process a second underlayer with a 1:3 isolated leave pattern formed below the first underlayer, thereby forming a 1:1 pattern with half the pitch.

[0463] In the pattern forming method of the present invention, a negative tone development method may be used in which an organic solvent is used as the developer instead of the alkaline aqueous solution to dissolve the unexposed areas.

[0464] The negative tone development may be carried out using, as a developer, 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 crotonate, or ethyl crotonate. Examples of organic solvents that can be used include methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, ethyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, and 2-phenylethyl acetate. These organic solvents may be used alone or in combination of two or more. [Example]

[0465] The present invention will be specifically described below using examples and comparative examples, but the present invention is not limited to these. The devices used are as follows. MALDI TOF-MS: JEOL S3000

[0466] [1] Synthesis of onium salt monomers [ka]

[0467] [Example 1-1] Synthesis of onium salt monomer PAG-1 (1) Synthesis of intermediate In-1 Under a nitrogen atmosphere, ethyl bromofluoroacetate (30.0 g), sodium sulfite (20.4 g), acetonitrile (120 g), and water (60 g) were added and stirred at 60°C for 5 hours. The reaction solution was transferred to a separatory funnel, and the aqueous layer was washed twice with hexane (50 g). Benzyltrimethylammonium chloride (30.1 g) and methylene chloride (150 g) were added to the resulting aqueous solution, and the mixture was stirred at room temperature for 1 hour. The reaction solution was transferred to a separatory funnel, and the organic layer was washed once with water (50 g). After separating the organic layer, the solvent was concentrated to obtain 42.4 g of intermediate In-1 as an oil (78% yield).

[0468] (2) Synthesis of intermediate In-2 Under a nitrogen atmosphere, intermediate In-1 (42.4 g) was dissolved in 22.2 g of a 25% by mass aqueous solution of sodium hydroxide and stirred at 40°C for 6 hours. 26.5 g of 20% by mass hydrochloric acid was then added to neutralize the reaction solution. 100 g of acetonitrile was then added and azeotropic dehydration was carried out to obtain 31.8 g of intermediate In-2 as an oil (yield 82%).

[0469] (3) Synthesis of intermediate In-3 Under a nitrogen atmosphere, intermediate In-2 (30.7 g), raw material SM-1 (37.2 g), 4-dimethylaminopyridine (DMAP) (1.2 g), and methylene chloride (200 g) were charged and cooled in an ice bath. While maintaining the temperature inside the reaction vessel at 20 °C or below, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (23.0 g) was added as a powder. After the addition, the mixture was warmed to room temperature and aged for 8 hours. After aging, water was added to quench the reaction. The solvent was then evaporated, yielding intermediate In-3 as an oil (yield: 60.8 g, 92%).

[0470] (4) Synthesis of Monomer PAG-1 Under a nitrogen atmosphere, intermediate In-3 (60.8 g), raw material SM-2 (37.5 g), methylene chloride (300 g), and water (150 g) were charged and stirred at room temperature for 30 minutes. The organic layer was separated, washed with water, and then concentrated under reduced pressure. The residue was washed with diisopropyl ether and concentrated to obtain 74.0 g of the onium salt monomer PAG-1 as an oil (yield 95%).

[0471] The results of TOF-MS of PAG-1 are shown below. MALDI TOF-MS:POSITIVE M + 335(C 18 H 11 F4S + equivalent) NEGATIVE M - 511(C 10 H6FI2O5S - equivalent)

[0472] [Examples 1-2 to 1-9] Synthesis of onium salt monomers PAG-2 to PAG-9 The onium salt monomers PAG-2 to PAG-9 shown below were synthesized using the corresponding raw materials and various organic synthesis reactions.

[0473] [ka]

[0474] [Comparative Examples 1-1 to 1-6] Synthesis of Comparative Onium Salt Monomers PAG-A to PAG-F Comparative onium salt monomers PAG-A to PAG-F shown below were synthesized using the corresponding raw materials and various organic synthesis reactions.

[0475] [ka]

[0476] [2] Synthesis of base polymer Among the monomers used in the synthesis of the base polymer, those other than PAG-1 to PAG-9 and PAG-A to PAG-F are as follows.

[0477] [ka]

[0478] [ka]

[0479] [ka]

[0480] [Example 2-1] Synthesis of Polymer P-1 Under a nitrogen atmosphere, a flask was charged with 43.0 g of monomer a1-1, 12.6 g of monomer b1-1, 44.5 g of monomer PAG-1, 4.04 g of V-601 (Wako Pure Chemical Industries, Ltd.), and 140 g of MEK to prepare a monomer-polymerization initiator solution. 46 g of MEK was charged to a separate flask under a nitrogen atmosphere and heated to 80°C with stirring. The monomer-polymerization initiator solution was then added dropwise over 4 hours. After the addition, the polymerization solution was stirred for 2 hours while maintaining the temperature at 80°C, and then cooled to room temperature. The resulting polymerization solution was added dropwise to 2,000 g of vigorously stirred hexane, and the precipitated polymer was filtered off. The resulting polymer was washed twice with 600 g of hexane and then vacuum-dried at 50°C for 20 hours to obtain polymer P-1 as a white powder (yield: 98.1 g, 98%). Polymer P-1 had an Mw of 9,200 and an Mw / Mn ratio of 1.63. Note that Mw was measured in terms of polystyrene by GPC using DMF as a solvent. [ka]

[0481] [Examples 2-2 to 2-26, Comparative Examples 2-1 to 2-18] Synthesis of Polymers P-2 to P-26 and CP-1 to CP-18 The polymers shown in Tables 1 and 2 were produced in the same manner as in Example 2-1, except that the types and compounding ratios of the respective monomers were changed.

[0482] [Table 1]

[0483] [Table 2]

[0484] [3] Preparation of chemically amplified resist composition [Examples 3-1 to 3-26, Comparative Examples 3-1 to 3-18] Base polymers (P-1 to P-26) containing onium salt-type monomers (PAG-1 to PAG-9) of the present invention, base polymers (CP-1 to CP-18) containing comparative onium salt-type monomers (PAG-A to PAG-F), photoacid generators (PAG-X, PAG-Y), and quenchers (Q-1 to Q-4) were dissolved in a solvent containing 0.01% by mass of surfactant A (Omnova) in the compositions shown in Tables 3 and 4 below to prepare solutions. The solutions were then filtered through a 0.2 μm Teflon (registered trademark) filter to prepare chemically amplified resist compositions (R-1 to R-26, CR-1 to CR-18).

[0485] [Table 3]

[0486] [Table 4]

[0487] In Tables 3 and 4, the solvents, photoacid generators PAG-X and PAG-Y, quenchers Q-1 to Q-4, and surfactant A are as follows.

[0488] Solvent: PGMEA (propylene glycol monomethyl ether acetate) EL (Ethyl lactate) DAA (diacetone alcohol)

[0489] Photoacid generator: PAG-X, PAG-Y [ka]

[0490] Quencher: Q-1~Q-4 [ka]

[0491] Surfactant A: 3-methyl-3-(2,2,2-trifluoroethoxymethyl)oxetane-tetrahydrofuran-2,2-dimethyl-1,3-propanediol copolymer (Omnova) [ka] a:(b+b'):(c+c')=1:4-7:0.01-1 (molar ratio) Mw=1,500

[0492] [4] EUV Lithography Evaluation (1) [Examples 4-1 to 4-26, Comparative Examples 4-1 to 4-18] Each chemically amplified resist composition (R-1 to R-26, CR-1 to CR-18) 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, and the substrate was pre-baked at 100°C for 60 seconds using a hot plate to produce a resist film with a thickness of 50 nm. The resist film was exposed to an LS pattern with an on-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) while varying the exposure dose and focus (exposure dose pitch: 1 mJ / cm). 2 After exposure, PEB was performed for 60 seconds at the temperatures shown in Tables 5 and 6. Thereafter, puddle development was performed with a 2.38 mass % TMAH aqueous solution for 30 seconds, followed by rinsing with a surfactant-containing rinse material and spin drying to obtain a positive pattern. The obtained LS patterns were observed using a critical dimension SEM (CG6300) manufactured by Hitachi High-Tech Corporation, and the sensitivity, EL, LWR, depth of focus (DOF), and tilt limit were evaluated according to the following methods. The obtained LS patterns were also evaluated for development defects. The results are shown in Tables 5 and 6.

[0493] [Sensitivity evaluation] The optimum exposure dose Eop (mJ / cm) to obtain an LS pattern with a line width of 18 nm and a pitch of 36 nm 2 The smaller this value, the higher the sensitivity.

[0494] [EL Evaluation] EL (unit: %) was calculated from the exposure amount formed within a range of ±10% (16.2 to 19.8 nm) of the 18 nm space width in the LS pattern using the following formula: The larger this value, the better the performance. EL(%)=(|E1-E2| / Eop)×100 E1: Optimal exposure dose for LS pattern with line width of 16.2 nm and pitch of 36 nm E2: Optimal exposure dose for LS pattern with line width of 19.8 nm and pitch of 36 nm Eop: Optimal exposure dose for LS pattern with line width of 18nm and pitch of 36nm

[0495] [LWR rating] The LS pattern obtained by irradiation with Eop was measured at 10 points along the line length, and the LWR was calculated as three times the standard deviation (σ) (3σ). The smaller this value, the less roughness and the more uniform the line width pattern obtained.

[0496] [DOF evaluation] For the evaluation of the depth of focus, the focus range formed within a range of ±10% (16.2 to 19.8 nm) of the 18 nm dimension of the LS pattern was determined. The larger this value, the wider the depth of focus.

[0497] [Line pattern collapse limit evaluation] The line dimension of the LS pattern at each exposure dose at the optimum focus was measured at 10 points in 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.

[0498] [Table 5]

[0499] [Table 6]

[0500] The results shown in Tables 5 and 6 demonstrate that chemically amplified resist compositions containing polymers containing repeating units derived from a monomeric photoacid generator made of an onium salt monomer of the present invention exhibit good sensitivity and excellent EL, LWR, and DOF. Furthermore, the collapse limit was small, demonstrating resistance to pattern collapse even in the formation of fine patterns. Therefore, the chemically amplified resist compositions of the present invention are suitable as materials for EUV lithography.

[0501] [5] EUV Lithography Evaluation (2) [Examples 5-1 to 5-26, Comparative Examples 5-1 to 5-18] Each chemically amplified resist composition (R-1 to R-26, CR-1 to CR-18) listed in Tables 3 and 4 was spin-coated onto a 20 nm thick silicon spin-on hard mask (SHB-A940, manufactured by Shin-Etsu Chemical Co., Ltd.) containing 43% silicon by weight. The resist was then pre-baked at 105°C for 60 seconds using a hot plate to produce a 50 nm thick resist film. The resist film was exposed to light using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple-pole illumination, 46 nm pitch on the wafer, and a hole pattern mask with a +20% bias). A 60-second PEB was performed using a hot plate at the temperatures listed in Tables 7 and 8, followed by development for 30 seconds in a 2.38% by weight aqueous TMAH solution to produce a 23 nm hole pattern. Using a Hitachi High-Technologies Corporation CD-SEM (CG6300), the exposure dose when a hole dimension of 23 nm was formed was measured and used as the sensitivity. The dimensions of 50 holes were also measured, and the CDU was calculated by multiplying the standard deviation (σ) by three (3σ). The results are shown in Tables 7 and 8.

[0502] [Table 7]

[0503] [Table 8]

[0504] The results shown in Tables 7 and 8 confirm that chemically amplified resist compositions containing polymers containing repeating units derived from monomeric photoacid generators made from onium salt-type monomers of the present invention have good sensitivity and excellent CDU.

[0505] The present specification includes the following aspects. [1]: An onium salt type monomer, characterized in that it is an onium salt type monomer represented by the following general formula (A): [ka] (In the formula, n1 is 0 or 1. n2 is an integer of 1 to 4. n3 is an integer of 0 to 4. However, when n1 is 0, 1≦n2+n3≦4, and when n1 is 1, 1≦n2+n3≦6. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 1is a halogen atom other than an iodine atom, a nitro group, a hydroxy group, a carboxy group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms. When n3 is 2, 3, or 4, each R 1 may be the same or different, and multiple R 1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 2 is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L A is a single bond, an ether bond, an ester bond, or a sulfonate ester bond. L B , L C and L D are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, or a carbamate bond. X L1 and X L2 are each independently a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. R F is a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Z + indicates an onium cation.) [2]: The onium salt type monomer according to the above [1], characterized in that the onium salt type monomer is represented by the following general formula (A1): [ka] (In the formula, R A , R 1 , R 2 , R F , L A , L B , L C , X L1 , X L2, n1 to n3 and Z + is the same as above.) [3]: The onium salt type monomer according to the above [2], wherein the onium salt type monomer represented by the general formula (A1) is represented by the following general formula (A2): [ka] (In the formula, R A , R 1 , R 2 , R F , L C , X L2 , n1 to n3 and Z + is the same as above.) [4]:Z above + is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2): [ka] (In the formula, R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. [5]: A monomeric photoacid generator, characterized in that it is made of an onium salt type monomer of any one of [1] to [4] above. [6]: A polymer characterized by containing a repeating unit derived from the monomeric photoacid generator of [5] above. [7]: The polymer according to [6] above, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following general formula (a1), a repeating unit represented by the following general formula (a2), and a repeating unit represented by the following general formula (a3): [ka] (In the formula, a1 is an integer of 0 to 4. R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 11 -, and the phenylene group or naphthylene group may be substituted with a hydroxy 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 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. X 2 is a single bond or *-C(=O)-O-. * indicates a bond to a carbon atom in the main chain. R 21 is a halogen atom, a cyano group, a hydroxy group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. 21 may be the same as or different from each other. AL 1 and AL 2 are each independently an acid labile group. [ka] (In the formula, b1 is 0 or 1. When b1 is 0, b2 is an integer of 0 to 3, and when b1 is 1, b2 is an integer of 0 to 5. RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 3 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. X 4 is 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 are each independently an oxygen atom or a sulfur atom, provided that X 4 and X 6 are attached to adjacent carbon atoms of the aromatic ring. R 22 and R 23 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 22 and R 23 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 24 is a halogen atom, a hydroxy group, a cyano group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, or —N(R 24A )(R 24B ) is R 24A and R 24B are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms. When b2 is 2 or more, each R 24 may be the same or different, and multiple R 24 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached.) [8]: The polymer according to [6] or [7] above, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following general formula (b1) and a repeating unit represented by the following general formula (b2): [ka] (In the formula, c1 is an integer of 1 to 4, and c2 is an integer of 0 to 4, provided that 1≦c1+c2≦5. R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 31 is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-). R 32 is a halogen atom, a carboxy group, a nitro group, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. 32 may be the same as or different from each other.) [9]: A chemically amplified resist composition, comprising: (A) a base polymer containing any one of the polymers described in [6] to [8] above.

[10] : The chemically amplified resist composition according to [9], further comprising one or more selected from the group consisting of (B) an organic solvent, (C) a quencher, (D) a photoacid generator other than the monomeric photoacid generator, and (E) a surfactant.

[11] : A pattern formation method, comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition according to [9] or

[10] above; exposing the resist film to high-energy rays; and developing the exposed resist film using a developer.

[12] : The pattern forming method according to

[11] above, wherein the high-energy beam is KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light having a wavelength of 3 to 15 nm.

[0506] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. An onium salt type monomer, characterized in that it is an onium salt type monomer represented by the following general formula (A): 【Chemistry 1】 (In the formula, n1 is 0 or 1. n2 is an integer of 1 to 4. n3 is an integer of 0 to 4. However, when n1 is 0, 1≦n2+n3≦4, and when n1 is 1, 1≦n2+n3≦6. R Ａ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R １ is a halogen atom other than an iodine atom, a nitro group, a hydroxy group, a carboxy group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms. １ may be the same or different, and multiple R １ may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R ２ is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L Ａ is a single bond, an ether bond, an ester bond, or a sulfonate ester bond. L Ｂ , L Ｃ and L Ｄ are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, or a carbamate bond. X Ｌ１ and X Ｌ２ are each independently a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. R Ｆ is a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Z ＋ indicates an onium cation.)

2. 2. The onium salt type monomer according to claim 1, wherein the onium salt type monomer is represented by the following general formula (A1): 【Chemistry 2】 (In the formula, R Ａ , R １ , R ２ , R Ｆ , L Ａ , L Ｂ , L Ｃ , X Ｌ１ , X Ｌ２ , n1 to n3 and Z ＋ is the same as above.)

3. 3. The onium salt type monomer according to claim 2, wherein the onium salt type monomer represented by the general formula (A1) is represented by the following general formula (A2): 【Transformation 3】 (In the formula, R Ａ , R １ , R ２ , R Ｆ , L Ｃ , X Ｌ２ , n1 to n3 and Z ＋ is the same as above.)

4. Said Z ＋ is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2): 【Chemistry 4】 (In the formula, R ｃｔ１ ~R ｃｔ５ are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ｃｔ１ and R ｃｔ２ may be bonded to each other to form a ring together with the sulfur atom to which they are attached.)

5. A monomeric photoacid generator, comprising the onium salt monomer according to any one of claims 1 to 4.

6. A polymer comprising a repeating unit derived from the monomeric photoacid generator according to claim 5.

7. The polymer according to claim 6, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following general formula (a1), a repeating unit represented by the following general formula (a2), and a repeating unit represented by the following general formula (a3): 【Transformation 5】 (In the formula, a1 is an integer of 0 to 4. R Ａ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X １ represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-X １１ -, and the phenylene group or naphthylene group may be substituted with a hydroxy 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 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. X ２ is a single bond or *-C(=O)-O-. * indicates a bond to a carbon atom in the main chain. R ２１ is a halogen atom, a cyano group, a hydroxy group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. ２１ may be the same as or different from each other. AL １ and AL ２ are each independently an acid labile group. 【Transformation 6】 (In the formula, b1 is 0 or 1. When b1 is 0, b2 is an integer of 0 to 3, and when b1 is 1, b2 is an integer of 0 to 5. R Ａ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X ３ is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. X ４ represents 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 groups. X ５ and X ６ are each independently an oxygen atom or a sulfur atom. ４ and X ６ are attached to adjacent carbon atoms of the aromatic ring. R ２２ and R ２３ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. ２２ and R ２３ may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R ２４ is a halogen atom, a hydroxy group, a cyano group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, or —N(R ２４Ａ ) (R ２４Ｂ ) R ２４Ａ and R ２４Ｂ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms. When b2 is 2 or more, each R ２４ may be the same or different, and multiple R ２４ may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded.)

8. The polymer according to claim 6, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following general formula (b1) and a repeating unit represented by the following general formula (b2): 【Transformation 7】 (In the formula, c1 is an integer of 1 to 4, and c2 is an integer of 0 to 4, provided that 1≦c1+c2≦5. R Ａ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y １ is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R ３１ is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride (-C(=O)-O-C(=O)-). R ３２ is a halogen atom, a carboxy group, a nitro group, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. ３２ may be the same as or different from each other.)

9. A chemically amplified resist composition, comprising (A) a base polymer comprising the polymer according to claim 6.

10. 10. The chemically amplified resist composition according to claim 9, further comprising at least one selected from the group consisting of (B) an organic solvent, (C) a quencher, (D) a photoacid generator other than the monomeric photoacid generator, and (E) a surfactant.

11. 10. A pattern formation method, comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition according to claim 9; exposing the resist film to high-energy rays; and developing the exposed resist film using a developer.

12. 12. The pattern formation method according to claim 11, wherein the high-energy beam is KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light having a wavelength of 3 to 15 nm.

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