Onium salt monomer, monomeric photoacid generator, polymer, chemically amplified resist composition, and patterning process

Abstract

To provide an onium salt type monomer excellent in solvent solubility, having high sensitivity and high contrast, excellent in EL, LWR, CDU and DOF, strong against pattern collapse and excellent also in etching resistance.SOLUTION: An onium salt monomer having the formula (a): Wherein RA is H, F, methyl or trifluoromethyl, RAL is an acid labile group, R1 is halogen, nitro, cyano or the like, R2 is halogen other than F, nitro, cyano or the like, RF is a fluorinated group, and Z + is an onium cation. ) SELECTED DRAWING: None

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 Documents 1 and 2). 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 3 describes a photoacid generator in which an iodine atom has been introduced into the anion, and Patent Document 4 describes a polymerizable group-containing photoacid generator in which an iodine atom has been introduced into the anion. Patent Document 5 describes a photoacid generator in which an iodine atom has been introduced into both the cation and the anion. While this has 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 Document 6 describes a photoacid generator in which multiple fluorine atoms are introduced into the cation. Although the introduction of multiple fluorine atoms improves the solvent solubility of the photoacid generator, this is not sufficient from the viewpoint of EUV absorption, and there is still room for improvement.

[0009] Patent Documents 7 to 11 describe photoacid generators and quenchers (acid diffusion controllers) containing iodine and fluorine atoms in the cation. Patent Documents 12 to 15 describe onium salt monomers in which an iodine atom and a polymerizable group are introduced into the cation. Patent Documents 16 and 17 describe onium salt monomers in which an iodine atom and a polymerizable group are introduced into the anion. While these developments have been confirmed to improve the performance of resist materials, they are still unsatisfactory in terms of acid diffusion control, and there is a need for the development of resist materials that are more useful for forming finer patterns. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 4425776 [Patent Document 2] International Publication No. 2023 / 063203 [Patent Document 3] Patent No. 6720926 [Patent Document 4] Patent No. 6973274 [Patent Document 5] Patent No. 7041204 [Patent Document 6] Patent No. 7389562 [Patent Document 7] Japanese Patent Publication No. 2021-123579 [Patent Document 8] Patent Publication No. 2021-123580 [Patent Document 9] Japanese Patent Application Publication No. 2022-123839 [Patent Document 10] Japanese Patent Application Publication No. 2023-88869 [Patent Document 11] Japanese Patent Application Publication No. 2023-88870 [Patent Document 12] Japanese Patent Publication No. 2022-28615 [Patent Document 13] Japanese Patent Application Publication No. 2023-93372 [Patent Document 14] Japanese Patent Application Publication No. 2023-165660 [Patent Document 15] Japanese Patent Publication No. 2023-171323 [Patent Document 16] Patent No. 6973274 [Patent Document 17] International Publication No. 2024 / 014462 Summary of the Invention [Problem to be solved by the invention]

[0011] There is a need for the development of acid-catalyzed chemically amplified resist compositions that have even higher sensitivity and can improve lithography performance such as exposure latitude (EL), LWR, CDU, and depth of focus (DOF), as well as exhibit excellent etching resistance after pattern formation.

[0012] The present invention has been made in view of the above circumstances, and has an object to provide an onium salt-type monomer and a monomer-type photoacid generator that can be used in a chemically amplified resist composition that, in photolithography, has excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance such as EL, LWR, CDU, and DOF, and is also resistant to pattern collapse in the formation of fine patterns and has excellent etching resistance; a polymer that contains a repeating unit derived from the onium salt-type monomer; a chemically amplified resist composition that contains the polymer; and a pattern formation method that uses the chemically amplified resist composition. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention provides an onium salt type monomer represented by the following formula (a): [ka] (In the formula, n1 is 0 or 1. n2 is 1, 2, 3, or 4. n3 is 0, 1, or 2. However, when n1 is 0, 1≦n2+n3≦3, and when n1 is 1, 1≦n2+n3≦5. n4 is 0 or 1. n5 is 0, 1, 2, 3, or 4. n6 is 0, 1, or 2. However, when n4 is 0, 0≦n5+n6≦4, and when n4 is 1, 0≦n5+n6≦6. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R AL is an acid labile group. R 1 is a halogen atom other than an iodine atom, a nitro group, a cyano group, a hydroxy group, an alkoxycarbonyl 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, or a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom. When n3 is 2, each R 1 may be the same or different, and two 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 halogen atom other than a fluorine atom, a nitro group, a cyano group, a hydroxy group, an alkoxycarbonyl 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, or a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom. When n6 is 2, each R 2 may be the same or different, and two R 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R F is a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a fluorinated saturated hydrocarbyloxy group having 1 to 6 carbon atoms, or a fluorinated saturated hydrocarbylthio group having 1 to 6 carbon atoms. When n5 is 2, 3, or 4, each R F may be the same as or different from each other. L A and L B are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, an amide bond, a sulfonate amide bond, a carbonate bond or a carbamate bond. X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. Z + is an onium cation.

[0014] Such an onium salt monomer can be used in a chemically amplified resist composition that exhibits excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance such as EL, LWR, CDU, and DOF, particularly in photolithography using high-energy rays such as KrF excimer laser light, ArF excimer laser light, electron beam (EB), and EUV, and that is resistant to pattern collapse even in fine pattern formation and has excellent etching resistance.

[0015] The onium salt type monomer of the present invention is preferably represented by the following formula (a1). [ka] (In the formula, n1~n6, R A , R AL , R 1 , R 2 , R F , L A , and Z + is the same as above.)

[0016] The onium salt type monomer of the present invention is more preferably represented by the following formula (a2). [ka] (In the formula, n1~n6, R A , R AL , R 1 , R 2 , R F , and Z+ is the same as above.)

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

[0018] Furthermore, the R AL The structure of the acid labile group represented by the following formula (AL-1) or (AL-2) is preferred. [ka] (Wherein, n6 is 0 or 1. n7 is 0 or 1. R L1 , R L2 and R L3 are each independently a hydrocarbyl group having 1 to 12 carbon atoms, in which some of the -CH2- groups in the hydrocarbyl group may be substituted with -O- or -S-, and when the hydrocarbyl group contains an aromatic ring, some or all of the hydrogen atoms in the aromatic ring may be substituted with a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 4 carbon atoms which may contain a halogen atom, or an alkoxy group having 1 to 4 carbon atoms which may contain a halogen atom. L1 and R L2 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded, and some of the -CH2- in the ring may be substituted with -O- or -S-. R L4 and R L5 R are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a hydrogen atom or a halogen atom. L6 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom, and a portion of the -CH2- in the hydrocarbyl group may be substituted with -O- or -S-. L5 and R L6 are bonded to each other and the carbon atoms to which they are bonded and L C may form a heterocyclic group having 3 to 20 carbon atoms together, and some of the -CH2- in the heterocyclic group may be substituted with -O- or -S-. L Cis —O— or —S—. * represents a bond to the adjacent -O-.)

[0019] If the acid labile group has such a structure, the effects of the present invention can be more fully exhibited.

[0020] In addition, the Z + is preferably a sulfonium cation represented by the following formula (Z-1) or an iodonium cation represented by the following 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.

[0021] Or, the above Z + The onium cation represented by the formula: may be a sulfonium cation represented by the following formula (Z-3). [ka] (Wherein, m1 is 0 or 1. m2 is 0 or 1. m3 is 0 or 1. m4 is 0, 1, 2, 3 or 4. m5 is 0, 1, 2, 3 or 4. m6 is 0, 1, 2, 3, 4, 5 or 6. m7 is 0, 1, 2, 3, 4, 5 or 6. m8 is 0, 1 or 2. m9 is 0, 1 or 2. m10 is 0, 1 or 2. m11 is 0 or 1. m12 is 0, 1, 2, 3 or 4. m13 is 0, 1 or 2. m14 is 0, 1 or 2. However, when m1 is 0, 0≦m6+m9≦4, and when m1 is 1, 0≦m6+m9≦6. When m2 is 0, 0≦m7+m10≦4, and when m2 is 1, 0≦m7+m10≦6. When m3 is 0, 1≦m4+m5+m8+m14≦4, and when m3 is 1, 1≦m4+m5+m8+m14≦6. When m11 is 0, 0≦m12+m13≦4, and when m11 is 1, 0≦m12+m13≦6. Also, m4+m12≧1. R F1 ~R F3 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. 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. R ct6 ~R ct9 is a halogen atom other than an iodine atom or a 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. 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 Rct7 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 ct9 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. In addition, S in the sulfonium cation + The aromatic rings directly bonded to S + may form a ring together with L D and L E 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. X L2 is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom.

[0022] In the present invention, such onium cations can be suitably used.

[0023] The present invention also provides a monomeric photoacid generator comprising the above onium salt monomer.

[0024] The onium salt type monomer of the present invention can be used as a photoacid generator by itself.

[0025] The present invention also provides a polymer containing repeating units derived from the above onium salt type monomer.

[0026] The polymer of the present invention is a polymer-bound photoacid generator that functions as both a base polymer and a photoacid generator in a chemically amplified resist composition.

[0027] The polymer of the present invention may further contain a repeating unit represented by the following formula (b1) or (b2): [ka] (In the formula, 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, *-C(=O)-OX 11 - or *-C(=O)-NH-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, *-C(=O)-O- or *-C(=O)-NH-. * indicates a bond to a carbon atom in the main chain. R 11 represents 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. AL 1 and AL 2 are each independently an acid labile group. a1 is 0, 1, 2, 3 or 4.

[0028] The polymer of the present invention may further contain a repeating unit represented by the following formula (b3): [ka] (In the formula, b1 is 0 or 1. When b1 is 0, b2 is 0, 1, 2, or 3, and when b1 is 1, b2 is 0, 1, 2, 3, 4, or 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. R 12 and R 13 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 12 and R 13 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 14 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 14A )(R 14B ) is R 14A and R 14B are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms. When b2 is 2 or more, multiple R 14 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached. 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 6are each independently an oxygen atom or a sulfur atom, provided that X 4 and X 6 are attached to adjacent carbon atoms of an aromatic ring.)

[0029] The polymer of the present invention may further contain a repeating unit represented by the following formula (c): [ka] (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. R 21 represents a halogen atom, a nitro group, a cyano 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 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 1, 2, 3, or 4. c2 is 0, 1, 2, or 3, provided that 1≦c1+c2≦5.

[0030] The polymer of the present invention may further contain a repeating unit represented by the following formula (d): [ka] (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z 1 represents a single bond, a phenylene group, a naphthylene group, *-C(=O)-OZ 11 -or*-C(=O)-NH-Z 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. * represents a bond to a carbon atom in the main chain. Z 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. R 31 is a hydrogen atom, or a group having 1 to 20 carbon atoms containing at least one structure selected from 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)-).

[0031] In the polymer of the present invention, various repeating units such as those described above can be copolymerized as needed.

[0032] The present invention also provides (A) a chemically amplified resist composition comprising a base polymer containing the above polymer.

[0033] The polymer of the present invention is a polymer-bound photoacid generator that functions as both a base polymer and a photoacid generator in a chemically amplified resist composition.

[0034] The chemically amplified resist composition of the present invention preferably further contains one or more selected from the group consisting of (B) an organic solvent, (C) a quencher, (D) an acid generator, (E) a surfactant, and (F) a dissolution inhibitor.

[0035] The chemically amplified resist composition of the present invention may contain various additives as required.

[0036] The present invention also provides a pattern formation method comprising the steps of forming a resist film on a substrate using the above-mentioned chemically amplified resist composition, exposing the resist film to high-energy rays, and developing the exposed resist film using a developer.

[0037] The pattern forming method of the present invention can form a pattern with high sensitivity and high contrast, particularly in photolithography using high-energy rays such as KrF excimer laser light, ArF excimer laser light, electron beam (EB), and EUV.

[0038] The high-energy radiation is preferably ArF excimer laser light with a wavelength of 193 nm, KrF excimer laser light with a wavelength of 248 nm, an electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

[0039] In the pattern forming method of the present invention, such high energy rays can be suitably used. [Effects of the Invention]

[0040] A polymer containing a repeating unit that generates acid upon exposure and is derived from an onium salt monomer having a polymerizable group and an iodine-substituted aromatic ring, the aromatic ring further bonded with a substituent containing an aromatic sulfonate anion structure and an acid-labile group, exhibits good solvent solubility due to its branched structure. In EUV lithography with a wavelength of 13.5 nm, the absorption of EUV light by iodine atoms is so strong that secondary electrons are generated from the iodine atoms during exposure. The aromatic sulfonate anion bonded to the polymerizable group and the iodine-substituted aromatic ring has a short distance from the polymer main chain to the acid generation site, and the secondary electrons generated from the iodine atoms promote the decomposition of cations located near the anion, resulting in efficient acid generation and high sensitivity. Furthermore, the large atomic weight of the iodine atom and the structure in which the generated acid is bonded to the polymer main chain result in low acid diffusion. The acid-labile group contained in the anion protects the aromatic hydroxyl group, and a deprotection reaction proceeds as the acid is generated. The aromatic hydroxyl group thus generated has increased acidity due to the electron-withdrawing effect of the iodine atom, and has a high affinity with alkaline developers. Therefore, when the exposed area is developed with an alkaline developer, the polymer residue is easily dissolved, improving the dissolution contrast between the exposed and unexposed areas. These synergistic effects can improve LWR and CDU. Furthermore, the aromatic ring in the repeating unit acts as a good etching-resistant group, making it suitable for forming fine patterns. DETAILED DESCRIPTION OF THE INVENTION

[0041] As described above, there has been a need for the development of an onium salt-type monomer for use in a chemically amplified resist composition that exhibits excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance in photolithography such as EL, LWR, CDU, and DOF, as well as resistance to pattern collapse in fine pattern formation and excellent etching resistance; a polymer containing a repeating unit derived from such an onium salt-type monomer; a chemically amplified resist composition containing such a polymer; and a pattern formation method using such a chemically amplified resist composition.

[0042] As a result of extensive research into achieving the above-mentioned object, the present inventors have found that a polymer containing a repeating unit derived from an onium salt-type monomer having a polymerizable group and an aromatic ring substituted with an iodine atom, and a structure in which a substituent containing an aromatic sulfonate anion structure and an acid labile group are further bonded to the aromatic ring, has good solvent solubility, and that by using this polymer as a polymer-bound photoacid generator, a chemically amplified resist composition can be obtained which has high sensitivity, high contrast, high resolution, improved lithography performance such as LWR and CDU, and which also has excellent etching resistance after pattern formation, and have completed the present invention.

[0043] That is, the present invention is an onium salt type monomer represented by the above formula (a).

[0044] The present invention will be described in detail below, but the present invention is not limited thereto.

[0045] [Onium salt type monomer] The onium salt type monomer of the present invention is represented by the following formula (a). [ka]

[0046] In 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 1, 2, 3, or 4. From the viewpoint of raw material procurement, n2 is preferably 1, 2, or 3, more preferably 1 or 2, and even more preferably 1. n3 is 0, 1, or 2. However, when n1 is 0, 1≦n2+n3≦3, and when n1 is 1, 1≦n2+n3≦5.

[0047] In formula (a), n4 is 0 or 1. When n4 is 0, it is a benzene ring, and when n4 is 1, it is a naphthalene ring. From the viewpoint of solvent solubility, n4 is preferably a benzene ring with n4 being 0. n5 is 0, 1, 2, 3, or 4, but may be any of the groups defined by R F When n4 is a fluorine atom, it is preferably 4. n6 is 0, 1 or 2. However, when n4 is 0, 0≦n5+n6≦4, and when n4 is 1, 0≦n5+n6≦6.

[0048] In 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, and a hydrogen atom is more preferred.

[0049] In formula (a), R AL is an acid labile group. The acid labile group is preferably a group represented by the following formula (AL-1) or (AL-2). [ka] (In the formula, * represents a bond to —O—.)

[0050] In formula (AL-1), n6 is 0 or 1. L1 , R L2 and R L3 are each independently a hydrocarbyl group having 1 to 12 carbon atoms, in which some of the -CH2- groups in the hydrocarbyl group may be substituted with -O- or -S-, and when the hydrocarbyl group contains an aromatic ring, some or all of the hydrogen atoms in the aromatic ring may be substituted with a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 4 carbon atoms which may contain a halogen atom, or an alkoxy group having 1 to 4 carbon atoms which may contain a halogen atom. L1 and R L2 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded, and some of the -CH2- in the ring may be substituted with -O- or -S-.

[0051] In formula (AL-2), n7 is 0 or 1.L4 and R L5 R are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a hydrogen atom or a halogen atom. L6 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom, and a portion of the -CH2- in the hydrocarbyl group may be substituted with -O- or -S-. L5 and R L6 are bonded to each other and the carbon atoms to which they are bonded and L C and L may form a heterocyclic group having 3 to 20 carbon atoms together, and some of the -CH2- in the heterocyclic group may be substituted with -O- or -S-. C is —O— or —S—.

[0052] Specific examples of the acid labile group represented by formula (AL-1) include, but are not limited to, the following: * represents a bond to the adjacent —O—.

[0053] [ka]

[0054] [ka]

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] [ka]

[0062] [ka]

[0063] [ka]

[0064] Specific examples of the acid labile group represented by formula (AL-2) include, but are not limited to, the following: * represents a bond to the adjacent —O—.

[0065] [ka]

[0066] [ka]

[0067] In formula (a), R 1is a halogen atom other than iodine atom, a nitro group, a cyano group, a hydroxy group, an alkoxycarbonyl 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, or a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom. The halogen atom other than iodine atom is preferably a fluorine atom, a chlorine atom, or a bromine atom, and more preferably a fluorine 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, and 4-methyl Examples of the alkyl group include saturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclohexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group; alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, an allyl group, a 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.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, each R. 1 may be the same as or different from each other.

[0068] Also, when n3 is 2, two R 1 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded. Specific examples of the ring formed 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.

[0069] In formula (a), R 2is a halogen atom other than a fluorine atom, a nitro group, a cyano group, a hydroxy group, an alkoxycarbonyl 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, or a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom. Specific examples of the halogen atom other than a fluorine atom include a chlorine atom, a bromine atom, and an iodine 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 R 1 When n6 is 2, each R 2 may be the same as or different from each other.

[0070] Also, when n6 is 2, two R 2 However, they may be bonded to each other to form a ring together with the carbon atoms to which they are bonded. The ring is preferably a 5- to 8-membered ring.

[0071] In formula (a), R F 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 fluorine atom, a trifluoromethyl group, a trifluoromethoxy group, or a trifluoromethylthio group is preferred, and a fluorine atom is more preferred. When n5 is 2, 3, or 4, each R F may be the same as or different from each other.

[0072] In formula (a), L A , L B are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, an amide bond, a sulfonate amide bond, a carbonate bond, or a carbamate bond. Ais 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. B The bond 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.

[0073] L A and -OR AL are preferably bonded to adjacent carbon atoms of the aromatic ring. In this case, the substituent containing the aromatic sulfonate anion structure and the acid labile group are located closer in space, which is expected to facilitate the deprotection reaction and further improve the dissolution contrast.

[0074] In formula (a), X L are each independently 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.

[0075] X L 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 following formula, * represents L A and L B It is a combination of.

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079] [ka]

[0080] Of these, X L -0~X L -22, X L -29~X L -34 and X L -47~X L -58 is preferred.

[0081] The onium salt type monomer represented by formula (a) is preferably one represented by the following formula (a1). [ka] (In the formula, n1~n6, R A , R AL , R 1 , R 2 , R F , L A , and Z + is the same as above.)

[0082] The onium salt type monomer represented by formula (a1) is preferably one represented by the following formula (a2). [ka] (In the formula, n1~n6, R A , R AL , R 1 , R 2 , R F , and Z + is the same as above.)

[0083] Examples of the anion of the onium salt type monomer represented by formula (a) include, but are not limited to, those shown below. Ais the same as above. The bonding positions of the various substituents on the aromatic ring may be interchanged.

[0084] [ka]

[0085] [ka]

[0086] [ka]

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[0147] In formula (a), Z + is an onium cation. The onium cation is preferably a sulfonium cation represented by the following formula (Z-1) or an iodonium cation represented by the following formula (Z-2). [ka]

[0148] In formulas (Z-1) and (Z-2), R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom.

[0149] R ct1 ~R ct5 Specific examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0150] R ct1 ~R ct5The 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, allyl, 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.

[0151] 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.

[0152] [ka] (In the formula, the dashed line indicates R ct3 )

[0153] Specific examples of the sulfonium cation represented by formula (Z-1) include those described in paragraphs

[0102] to

[0125] of JP-A No. 2024-003744 and those described in paragraphs

[0070] to

[0085] of JP-A No. 2023-169812, but are not limited thereto.

[0154] Specific examples of the iodonium cation represented by formula (Z-2) include, but are not limited to, those described in paragraph

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

[0155] 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]

[0156] In 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.

[0157] In formula (Z-3), m4 is 0, 1, 2, 3, or 4. The greater the number of iodine atoms in the cation structure, the greater the absorption, particularly of EUV, but the fewer the number of iodine atoms, the greater the solvent solubility and the less likely the compound will precipitate in the resist composition. Therefore, m4 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2.

[0158] In formula (Z-3), m5 is 0, 1, 2, 3, or 4. From the viewpoint of raw material procurement, m5 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2. m6 is 0, 1, 2, 3, 4, 5, or 6. From the viewpoint of raw material procurement, m6 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2. m7 is 0, 1, 2, 3, 4, 5, or 6. From the viewpoint of raw material procurement, m7 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2.

[0159] In 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.

[0160] In 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.

[0161] In formula (Z-3), m12 is 0, 1, 2, 3, or 4. The greater the number of iodine atoms in the cation structure, the greater the absorption, particularly of EUV, but the fewer the number of iodine atoms, the greater the solvent solubility and the less likely the compound will precipitate in the resist composition. Therefore, m12 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2.

[0162] In 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.

[0163] 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 m13 is 1, 1≦m4+m5+m8+m14≦6. When m11 is 0, 0≦m12+m13≦4, and when m11 is 1, 0≦m12+m13≦6. Also, m4+m12≧1.

[0164] In 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.

[0165] In formula (Z-3), R ct6 ~R ct9 is a halogen atom other than iodine and fluorine atoms, 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 1In 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.

[0166] 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.

[0167] In addition, S in the sulfonium cation represented by 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:

[0168] [ka] (In the formula, the dashed lines represent bonds.)

[0169] In formula (Z-3), L D and L E 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. D 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. E is preferably a single bond, an ether bond or an ester bond, and more preferably a single bond.

[0170] In formula (Z-3), X L2 is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. Specific examples of the hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom include X L Specific examples of the hydrocarbylene group having 1 to 40 carbon atoms and optionally containing a hetero atom, represented by the following formula, include, but are not limited to, the same as those exemplified above.

[0171] The sulfonium cation represented by formula (Z-3) is preferably one represented by the following formula (Z-3-1). [ka] (In the formula, m4~m10, m12~m14, R F1 ~R F3 , R ct6 ~R ct9 , L D , L E and X L2 is the same as above.)

[0172] The cation represented by formula (Z-3-1) is preferably one represented by the following formula (Z-3-2). [ka] (In the formula, m4~m10, R F1 ~R F3 and R ct6 ~R ct8 is the same as above.)

[0173] Specific examples of the sulfonium cation represented by formula (Z-3) include, but are not limited to, the following: In the following formula, Me is a methyl group.

[0174] [ka]

[0175] [ka]

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[0197] [ka]

[0198] [ka]

[0199] [ka]

[0200] [ka]

[0201] [ka]

[0202] Specific examples of the onium salt of the present invention include any combination of the above-mentioned anions and cations.

[0203] The onium salt monomer of the present invention can be synthesized by a known method. Specifically, when an acetal-type acid labile group is introduced into the following intermediate (In-1-ex), which can be synthesized using a known organic synthesis reaction, the acetal-type acid labile group can be introduced by reacting the corresponding chloromethyl alkyl ether under basic conditions. Alternatively, a carbonate-type acid labile group can be introduced by reacting an alkyl chloroformate derived from a tertiary alcohol under basic conditions.

[0204] [ka] (In the formula, n1~n6, R A , R 1 , R 2 , R F , L A , L B , XL , and Z + is the same as above.)

[0205] 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.

[0206] Furthermore, the onium salt type monomer of the present invention can be used by itself as a monomer type photoacid generator.

[0207] [polymer] The polymer of the present invention contains a repeating unit derived from an onium salt monomer represented by formula (a) (hereinafter also referred to as repeating unit a).

[0208] The polymer of the present invention is a polymer-bound photoacid generator that functions as both a base polymer and a photoacid generator in a chemically amplified resist composition. The structural feature of the onium salt-type monomer of the present invention is that the anion contains an acid-labile group, which increases the carbon number and thereby provides good solvent solubility. The acid-labile group in the anion undergoes a deprotection reaction upon acid generation, generating an aromatic hydroxy group, thereby providing dissolution contrast. Furthermore, the iodine atom in the anion has extremely high EUV absorption in 13.5 nm EUV lithography, generating secondary electrons from the iodine atom during exposure. The anionic structure is bound to the polymerizable group and the iodine-substituted aromatic ring, allowing the secondary electrons generated from the iodine atom to promote decomposition of cations located near the anion, thereby efficiently generating acid and achieving high sensitivity. Furthermore, the large atomic weight of the iodine atom and the structure in which the generated acid is bound to the polymer backbone chain result in low acid diffusion. Polymerizable groups containing styrene or vinylnaphthalene structures are more rigid than polymerizable groups such as methacrylate esters, improving the glass transition temperature (Tg) of the polymer. Interactions between aromatic rings within or between base polymers (π-π stacking effect) result in the regular arrangement of the base polymer, which is thought to contribute to the development of resistance to pattern collapse in developing solutions during fine pattern formation. Furthermore, the aromatic rings directly connected to the main chain contribute to excellent etching resistance during the etching process after fine pattern formation. A triarylsulfonium cation containing a fluorine atom is preferably used as the cation. The electron-withdrawing effect of the fluorine atom lowers the LUMO energy level in frontier orbital theory, making it easier to accept generated secondary electrons, thereby promoting cation decomposition and effectively generating acid. These synergistic effects result in high sensitivity. This prevents resolution degradation due to acid diffusion blurring and improves LWR and CDU. Therefore, the polymer of the present invention is particularly suitable as a material for chemically amplified positive resist compositions.

[0209] The polymer may further include a repeating unit represented by the following formula (b1) (hereinafter also referred to as repeating unit b1) or a repeating unit represented by the following formula (b2) (hereinafter also referred to as repeating unit b2).

[0210] [ka]

[0211] In formulas (b1) and (b2), R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0212] In formula (b1), X 1 represents a single bond, a phenylene group, a naphthylene group, *-C(=O)-OX 11 - or *-C(=O)-NH-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. * represents a bond to a carbon atom in the main chain.

[0213] In formula (b2), X 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. R 11represents 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 0, 1, 2, 3 or 4, and preferably 0 or 1.

[0214] In formulas (b1) and (b2), AL 1 and AL 2 are each independently an acid labile group. Specific examples of the acid labile group include, but are not limited to, those described in JP-A Nos. 2013-80033 and 2013-83821.

[0215] Typical examples of the acid labile group include those represented by the following formulae (AL-1) to (AL-3). [ka] (In the formula, * represents a bond.)

[0216] In 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, a fluorine atom, or an iodine 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.

[0217] In formula (AL-1), a2 represents an integer of 0 to 10, and is preferably 1, 2, 3, 4 or 5.

[0218] In formula (AL-2), R L3 and R L4are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, fluorine, and iodine. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. 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.

[0219] In 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, a fluorine atom, or an iodine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. L5 , R L6 and R L7 Any two of these may be bonded to each other together with the carbon atoms to which they are bonded to form 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.

[0220] Specific examples of the repeating unit b1 include, but are not limited to, the following: A and AL 1 is the same as above.

[0221] [ka]

[0222] [ka]

[0223] [ka]

[0224] [ka]

[0225] [ka]

[0226] [ka]

[0227] [ka]

[0228] Specific examples of the repeating unit b2 include, but are not limited to, those shown below. A and AL 2 is the same as above.

[0229] [ka]

[0230] [ka]

[0231] [ka]

[0232] The polymer may further contain a repeating unit represented by the following formula (b3) (hereinafter also referred to as repeating unit b3). [ka]

[0233] In formula (b3), b1 is 0 or 1. When b1 is 0, it is a benzene ring, and when b1 is 1, it is a naphthalene ring; however, from the viewpoint of solvent solubility, it is preferable that b1 is a benzene ring of 0. When b1 is 0, b2 is 0, 1, 2, or 3, and when b1 is 1, it is 0, 1, 2, 3, 4, or 5. From the viewpoint of raw material procurement, b2 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2.

[0234] In formula (b3), 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.

[0235] In formula (b3), 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.

[0236] In formula (b3), R 12 and R 13are 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, and 4-methyl Examples of the alkyl group include saturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclohexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group; alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, an allyl group, a 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 2 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.

[0237] Also, R 12 and R 13may 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.

[0238] In formula (b3), R 14 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 14A )(R 14B ) R 14A and R 14B 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, 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 12 and R 13Examples 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 14 may be the same as or different from each other.

[0239] Also, when b2 is 2 or more, multiple R 14 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.

[0240] In formula (b3), 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. 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.

[0241] In formula (b3), 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.

[0242] Specific examples of the repeating unit b3 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.

[0243] [ka]

[0244] [ka]

[0245] [ka]

[0246] [ka]

[0247] [ka]

[0248] [ka]

[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]

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[0259]

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[0260]

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[0261]

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[0262]

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[0263]

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[0264]

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[0265]

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[0266]

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[0267]

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[0268]

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[0269]

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[0270]

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[0271]

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[0272]

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[0273]

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[0274]

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[0275]

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[0276]

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[0277]

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[0278]

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[0279]

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[0280]

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[0281]

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[0282]

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[0283]

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[0286]

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[0287]

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[0288]

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[0289]

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[0290]

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[0291] [ka]

[0292] [ka]

[0293] The polymer preferably further contains a repeating unit represented by the following formula (c) (hereinafter also referred to as repeating unit c). [ka]

[0294] In formula (c), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. R 21 is a halogen atom, a nitro group, a cyano 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 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 1, 2, 3, or 4. c2 is 0, 1, 2, or 3, provided that 1≦c1+c2≦5.

[0295] Specific examples of the repeating unit c include, but are not limited to, those shown below. A is the same as above.

[0296] [ka]

[0297] [ka]

[0298] [ka]

[0299] [ka]

[0300] [ka]

[0301] The polymer preferably further contains a repeating unit represented by the following formula (d) (hereinafter also referred to as repeating unit d). [ka]

[0302] In formula (d), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 represents a single bond, a phenylene group, a naphthylene group, *-C(=O)-OZ 11 -or*-C(=O)-NH-Z 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. * represents a bond to a carbon atom in the main chain. Z 11 R 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. 31is 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)-).

[0303] Specific examples of the repeating unit d include, but are not limited to, those shown below. A is the same as above.

[0304] [ka]

[0305] [ka]

[0306] [ka]

[0307] [ka]

[0308] [ka]

[0309] [ka]

[0310] [ka]

[0311] [ka]

[0312] [ka]

[0313] [ka]

[0314] [ka]

[0315] [ka]

[0316] [ka]

[0317] [ka]

[0318] [ka]

[0319] [ka]

[0320] As the repeating unit d, in ArF lithography, those having a lactone ring as a polar group are particularly preferred, and in KrF lithography, EB lithography and EUV lithography, those having a phenol moiety are preferred.

[0321] The polymer may further 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 e). The repeating unit e 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 formula (e):

[0322] [ka]

[0323] In formula (e1), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 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 1, 2, 3 or 4.

[0324] In formula (e), 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, an alkoxymethyl group, etc. are preferred, and an alkoxymethyl group represented by the following formula (e1) is particularly preferred.

[0325] [ka] (In the formula, * represents a bond. R 43 is a hydrocarbyl group having 1 to 15 carbon atoms.

[0326] R 42 Specific examples of the acid labile group represented by the formula (e1), the alkoxymethyl group represented by the formula (e2), and the repeating unit e are the same as those exemplified in the description of the repeating unit d described in JP-A-2020-111564.

[0327] The polymer may further contain a repeating unit f derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene or derivatives thereof. Specific examples of the monomer that gives the repeating unit f include, but are not limited to, those shown below.

[0328] [Chemical formula]

[0329] The polymer may further contain a repeating unit g derived from styrene, indane, vinyl pyridine or vinyl carbazole.

[0330] In the polymer of the present invention, the content ratios of the repeating units a, b1, b2, b3, c, d, e, f and g are preferably 0 < a ≤ 0.5, 0 ≤ b1 ≤ 0.8, 0 ≤ b2 ≤ 0.8, 0 ≤ b3 ≤ 0.6, 0 ≤ c ≤ 0.8, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 0.3, 0 ≤ f ≤ 0.3 and 0 ≤ g ≤ 0.3, and more preferably 0 < a ≤ 0.4, 0 ≤ b1 ≤ 0.7, 0 ≤ b2 ≤ 0.7, 0 ≤ b3 ≤ 0.5, 0 ≤ c ≤ 0.7, 0 ≤ d ≤ 0.4, 0 ≤ e ≤ 0.2, 0 ≤ f ≤ 0.2 and 0 ≤ g ≤ 0.2. However, a + b1 + b2 + b3 + c + d + e + f + g ≤ 1.0.

[0331] The weight average molecular weight (Mw) of the polymer is preferably from 1,000 to 500,000, more preferably from 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 the resolution due to the inability to ensure the difference in dissolution rate before and after exposure. In the present invention, Mw is a polystyrene equivalent measurement value by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or N,N-dimethylformamide (DMF) as a solvent. When measuring GPC, it is usually carried out at room temperature around 23 degrees, but it may also be carried out at a higher or lower temperature.

[0332] 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. Within this range, there is little low-molecular-weight or high-molecular-weight polymer, and there is no risk of foreign matter being observed on the pattern or deterioration of the pattern shape after exposure.

[0333] The polymer can be synthesized, for example, by polymerizing a monomer that provides the repeating unit described above in an organic solvent with the addition of a radical polymerization initiator by heating.

[0334] 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.

[0335] 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. From the perspective of quality control, it is preferable to prepare the monomer solution and the initiator solution independently and then add them dropwise, since 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. The acid labile group may be used as is after being introduced into the monomer, 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 the chain transfer agent added is preferably 0.01 to 20 mol % of the total amount of monomers to be polymerized.

[0336] 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.

[0337] 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.

[0338] Specific examples of the base that can be used in alkaline hydrolysis include 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.

[0339] 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.

[0340] 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 a polymerization 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.

[0341] 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.

[0342] 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.

[0343] 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.

[0344] Examples of filter materials used in the filter filtration include fluorocarbon, cellulose, nylon, polyester, and hydrocarbon-based materials. However, in the filtration process for chemically amplified 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 desired 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 during the polymer production process. However, it is preferable to filter the reaction solution after the polymerization reaction, the polymer solution, or both.

[0345] [Chemically amplified resist composition] [(A) Base polymer] The chemically amplified resist composition of the present invention contains, as component (A), a base polymer containing the above-mentioned polymer.

[0346] 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 also contain a hydrogenated ring-opening metathesis polymer, and those described in JP-A-2003-66612 can be used.

[0347] Furthermore, the amount of component (A) in the chemically amplified resist composition of the present invention is not particularly limited, but can be, for example, 0.1 to 10 parts by mass, and preferably 0.5 to 5 parts by mass, per 100 parts by mass of the total amount of the composition.

[0348] [(B) Organic solvent] The chemically amplified resist composition of the present invention may contain an organic solvent as component (B). There are no particular limitations on the organic solvent (B) 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.

[0349] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, cyclohexanone, GBL, DAA, and mixed solvents thereof are preferred, as they have particularly excellent solubility for the base polymer of component (A).

[0350] In the chemically amplified resist composition of the present invention, the content of (B) organic solvent is preferably 200 to 5000 parts by mass, more preferably 400 to 3500 parts by mass, relative to 80 parts by mass of (A) base polymer. (B) Organic solvent may be used singly or in combination of two or more types.

[0351] [(C) Quencher] The chemically amplified resist composition of the present invention may contain a quencher as component (C). In this 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.

[0352] Specific examples of the (C) quencher include onium salts represented by the following formula (1) or (2). [ka]

[0353] In formula (1), R q1 represents 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.

[0354] R q1 Specific 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]. 2,6cyclic 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.

[0355] 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.

[0356] Specific examples of the anion of the onium salt represented by formula (1) include, but are not limited to, those shown below.

[0357] [ka]

[0358] [ka]

[0359] [ka]

[0360] [ka]

[0361] [ka]

[0362] Specific examples of the anion of the onium salt represented by formula (2) include, but are not limited to, those shown below.

[0363] [ka]

[0364] [ka]

[0365] [ka]

[0366] [ka]

[0367] [ka]

[0368] In equations (1) and (2), Mq + is an onium cation. The onium cation is preferably a sulfonium cation represented by the above formula (Z-1) or (Z-3), an iodonium cation represented by the above formula (Z-2), or an ammonium cation represented by the following formula (am-1):

[0369] [ka]

[0370] In formula (am-1), Rq11 ~R q14 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. q11 and R q12 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 R ct1 ~R ct5 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0371] Specific examples of the ammonium cation represented by formula (am-1) include, but are not limited to, those shown below.

[0372] [ka]

[0373] Specific examples of the onium salt represented by 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.

[0374] The onium salt represented by formula (1) or (2) functions as a quencher in the chemically amplified resist composition of the present invention. This is because the counter anion of each onium salt is the conjugate base of a weak acid. The term "weak acid" as used herein refers to an acidity that is insufficient to deprotect the acid labile group in the acid labile group-containing unit used in the base polymer. The onium salt represented by formula (1) or (2) functions as a quencher when used in combination with an onium salt-type photoacid generator having a 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.

[0375] 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.

[0376] 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.

[0377] When the chemically amplified resist composition of the present invention contains an onium salt represented by 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 formula (1) or (2) may be used alone or in combination of two or more.

[0378] 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. Other examples include compounds in which a primary or secondary amine is protected with a carbamate group, as described in JP 3790649 A. Furthermore, examples include compounds having an acid labile group in the molecule, as described in JP 2009-109595 A.

[0379] 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 2012-46501 can be used as references for the photodegradable base.

[0380] 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.

[0381] [(D) Acid generator] The chemically amplified resist composition of the present invention may contain an acid generator. Examples of the acid generator include compounds (photoacid generators) that generate acid in response to actinic rays or radiation. The photoacid generator is not particularly limited as long as it generates an acid upon exposure to high-energy rays, but preferred are those that generate sulfonic acid, imide acid, or methide acid. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate-type acid generators. Specific examples of acid generators include those described in paragraphs

[0122] to

[0142] of JP 2008-111103 A.

[0382] Furthermore, as the photoacid generator, a sulfonium salt represented by the following formula (3-1) or an iodonium salt represented by the following formula (3-2) can also be suitably used. [ka]

[0383] In formulas (3-1) and (3-2), 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. Specific examples of the halogen atom and hydrocarbyl group include R ct1 ~R ct5Examples of the halogen atom and hydrocarbyl group include those exemplified above. In addition, some or all of the hydrogen atoms in 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- in 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 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, or the like. In addition, R 101 and R 102 However, they may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. Specific examples of the ring formed in this case include R ct1 and R ct2 are bonded to each other to form a ring together with the sulfur atom to which they are bonded, the same as those exemplified above.

[0384] Specific examples of the cation of the sulfonium salt represented by formula (3-1) include the same as those exemplified as the sulfonium cations represented by formulas (Z-1) and (Z-3). Specific examples of the cation of the iodonium salt represented by formula (3-2) include the same as those exemplified as the iodonium cation represented by formula (Z-2).

[0385] In formulas (3-1) and (3-2), Xa - is an anion selected from the following formulae (3A) to (3D).

[0386] [ka]

[0387] In formula (3A), R fais 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 formula (3A') described below. fa1 Examples include those similar to those exemplified in the explanation of .

[0388] The anion represented by formula (3A) is preferably one represented by the following formula (3A'). [ka]

[0389] In formula (3A'), R HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group.

[0390] In formula (3A'), R fa1 is a hydrocarbyl group having 1 to 38 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.

[0391] R fa1The hydrocarbyl group having 1 to 38 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 38 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, 2-ethylhexyl, nonyl, undecyl, tridecyl, pentadecyl, heptadecyl, and icosyl groups; cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, 1-adamantylmethyl, and norbornyl. Examples of such groups include saturated cyclic hydrocarbyl groups having 3 to 38 carbon atoms, such as an allyl group, a norbornylmethyl group, a tricyclodecyl group, a tetracyclododecyl group, a tetracyclododecylmethyl group, and a dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 38 carbon atoms, such as an allyl group and a 3-cyclohexenyl group; aryl groups having 6 to 38 carbon atoms, such as a phenyl group, a 1-naphthyl group, and a 2-naphthyl group; aralkyl groups having 7 to 38 carbon atoms, such as a benzyl group and a diphenylmethyl group; and groups obtained by combining these groups.

[0392] 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, or 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, resulting in the hydrocarbyl group 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, etc. The heteroatom is preferably an oxygen atom. 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.

[0393] Synthesis of sulfonium salts containing anions represented by formula (3A') is described in detail in JP-A Nos. 2007-145797, 2008-106045, 2009-7327, and 2009-258695. Sulfonium salts described in JP-A Nos. 2010-215608, 2012-41320, 2012-106986, and 2012-153644 are also suitable.

[0394] Specific examples of the anion represented by formula (3A) include, but are not limited to, those shown below: In the following formula, Ac is an acetyl group.

[0395] [ka]

[0396] [ka]

[0397] [ka]

[0398] [ka]

[0399] In formula (3B), 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 formula (3A'). fa1 Examples of the hydrocarbyl group represented by R include the same as those exemplified above. fb1 and R fb2is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 means that the groups to which they are bonded (-CF2-SO2-N - -SO2-CF2-) together to 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.

[0400] In formula (3C), 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 formula (3A'). fa1 Examples 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 groups that are bonded together and bonded to each other (-CF2-SO2-C - -SO2-CF2-) together to 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.

[0401] In formula (3D), 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 formula (3A'). fa1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0402] The synthesis of sulfonium salts containing anions represented by formula (3D) is described in detail in JP-A-2010-215608 and JP-A-2014-133723.

[0403] Specific examples of the anion represented by formula (3D) include, but are not limited to, those shown below.

[0404] [ka]

[0405] [ka]

[0406] Although the photoacid generator containing the anion represented by formula (3D) does not have a fluorine atom at the α-position of the sulfo group, it has two trifluoromethyl groups at the β-position, and therefore has sufficient acidity to cleave the acid labile groups in the base polymer, making it suitable for use as a photoacid generator.

[0407] As the photoacid generator, a compound represented by the following formula (4) can also be suitably used. [ka]

[0408] In formula (4), 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 these 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 include R ct1 and R ct2are bonded to each other to form a ring together with the sulfur atom to which they are bonded, the same as those exemplified above.

[0409] 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, an n-pentyl group, a tert-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] 2,6 cyclic 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.

[0410] 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; cyclopentanediyl group, cyclohexene-1,18-diyl group, and the like. Examples of the alkylene groups include cyclic saturated hydrocarbylene groups having 3 to 30 carbon atoms, such as xanediyl, norbornanediyl, and adamantanediyl; arylene groups having 6 to 30 carbon atoms, such as phenylene, methylphenylene, ethylphenylene, n-propylphenylene, isopropylphenylene, n-butylphenylene, isobutylphenylene, sec-butylphenylene, tert-butylphenylene, naphthylene, methylnaphthylene, ethylnaphthylene, n-propylnaphthylene, isopropylnaphthylene, n-butylnaphthylene, isobutylnaphthylene, sec-butylnaphthylene, and tert-butylnaphthylene; and groups obtained by combining these groups. 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.

[0411] In formula (4), L1 is 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.

[0412] In formula (4), 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.

[0413] In formula (4), k is 0, 1, 2 or 3.

[0414] The photoacid generator represented by formula (4) is preferably one represented by the following formula (4'). [ka]

[0415] In formula (4'), L 1 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 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 formula (3A'). fa1 Examples of the hydrocarbyl group include the same as those exemplified above. x and y are each independently 0, 1, 2, 3, 4, or 5. z is 0, 1, 2, 3, or 4.

[0416] Specific examples of the photoacid generator represented by formula (4) include the same compounds as those exemplified as the photoacid generator represented by formula (2) in JP-A-2017-26980.

[0417] Among the photoacid generators, those containing an anion represented by formula (3A') or (3D) are particularly preferred because of their small acid diffusion and excellent solubility in solvents. Also, those represented by formula (4') are particularly preferred because of their extremely small acid diffusion.

[0418] As other acid generators, sulfonium salts and iodonium salts containing an anion having an aromatic ring substituted with an iodine atom, represented by the following formula (5-1) or (5-2), can also be used.

[0419] [ka]

[0420] In formulas (5-1) and (5-2), p is 1, 2, or 3. q is 1, 2, 3, 4, or 5. r is 0, 1, 2, or 3, provided that 1≦q+r≦5. q is preferably 1, 2, or 3, and more preferably 2 or 3. r is preferably 0, 1, or 2.

[0421] In formulas (5-1) and (5-2), L 11 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.

[0422] In formulas (5-1) and (5-2), L 12 represents a single bond or a divalent linking group having 1 to 20 carbon atoms when p is 1, and represents a (p+1)-valent linking group having 1 to 20 carbon atoms when p is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0423] In formulas (5-1) and (5-2), R 401 is a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom or 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 401A )(R 401B ), -N(R 401C )-C(=O)-R 401D or -N(R 401C )-C(=O)-OR 401D R 401A and R 401B are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 401C 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. 401D is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 14 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 p and / or r is 2 or more, each R 401 may be the same or different from each other.

[0424] Of these, R 401 Examples of the hydroxyl group include -N(R 401C )-C(=O)-R 401D , -N(R 401C )-C(=O)-OR 401D fluorine atom, chlorine atom, bromine atom, methyl group, methoxy group, etc. are preferred.

[0425] In formulas (5-1) and (5-2), Rf 1 ~Rf 4 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. 1 and Rf 2 may combine to form a carbonyl group. 3 and Rf 4 are preferably both fluorine atoms.

[0426] In formulas (5-1) and (5-2), R 402 ~R 406 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R ct1 ~R ct5 Examples 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 hydroxy group, a carboxy group, a halogen atom, a cyano group, a nitro group, a mercapto group, a sultone ring, a sulfo group, or a sulfonium salt-containing group, and some of the -CH2- groups of the hydrocarbyl group may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, or a sulfonate ester bond. 402 and R 403 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 include those represented by R ct1 and R ct2are bonded to each other to form a ring together with the sulfur atom to which they are bonded, the same as those exemplified above.

[0427] Specific examples of the cation of the sulfonium salt represented by formula (5-1) include the same as those exemplified as the sulfonium cation represented by formula (Z-1). Specific examples of the cation of the iodonium salt represented by formula (5-2) include the same as those exemplified as the iodonium cation represented by formula (Z-2).

[0428] Specific examples of the anion of the onium salt represented by formula (5-1) or (5-2) include, but are not limited to, those shown below.

[0429] [ka]

[0430] [ka]

[0431] [ka]

[0432] [ka]

[0433] [ka]

[0434] [ka]

[0435] [ka]

[0436]

change

[0437]

change

[0438]

change

[0439]

change

[0440]

change

[0441]

change

[0442]

change

[0443]

change

[0444]

change

[0445]

change

[0446]

change

[0447] [ka]

[0448] [ka]

[0449] [ka]

[0450] [ka]

[0451] When the chemically amplified resist composition of the present invention contains an acid generator (D), 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 base polymer (A). When the amount of the acid generator (D) added 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 acid generator (D) may be used alone or in combination of two or more types.

[0452] [(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-2011-16746.

[0453] 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 formula (surf-1):

[0454] [ka]

[0455] Here, R, Rf, A, B, C, m, and n apply only to 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:

[0456] [ka] (In the formula, the dashed lines represent bonds and are partial structures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.)

[0457] Among these, a 1,4-butylene group, a 2,2-dimethyl-1,3-propylene group, and the like are preferred.

[0458] 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 formula (surf-1) is not specified, and they may be bonded in blocks or randomly. The production of surfactants based on partially fluorinated oxetane ring-opening polymers is described in detail in the specification of U.S. Pat. No. 5,650,483, etc.

[0459] 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.

[0460] Specific examples of such polymer surfactants include those containing at least one repeating unit selected from the repeating units represented by the following formulas (6A) to (6E).

[0461] [ka]

[0462] In 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. s1are 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 (u+1). u is 1, 2, or 3. R s5 are 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.

[0463] 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.

[0464] 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.

[0465] 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. Specific examples of the saturated hydrocarbyl group include 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 s6 Specific examples 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.

[0466] R s3 Specific examples of the acid labile group represented by the formula (AL-1) to (AL-3) include the groups represented by the formulas (AL-1) to (AL-3) above, 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.

[0467] R s4 The (u+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 u hydrogen atoms from the aforementioned hydrocarbyl group or fluorinated hydrocarbyl group.

[0468] R saThe 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.

[0469] Specific examples of the repeating unit represented by any one of formulas (6A) to (6E) include, but are not limited to, the following: B is the same as above.

[0470] [ka]

[0471] [ka]

[0472] [ka]

[0473] [ka]

[0474] [ka]

[0475] The polymer surfactant may further contain other repeating units in addition to the repeating units represented by formulae (6A) to (6E). Specific examples of other repeating units include repeating units obtained from methacrylic acid, α-trifluoromethylacrylic acid derivatives, etc. In the polymer surfactant, the content of the repeating units represented by formulae (6A) to (6E) in all repeating units is preferably 20 mol % or more, more preferably 60 mol % or more, and even more preferably 100 mol %.

[0476] 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.

[0477] The polymeric surfactant can be synthesized by heating a monomer containing an unsaturated bond that provides the repeating units represented by formulas (6A) to (6E) and, if necessary, other repeating units, in an organic solvent with the addition of a radical initiator to polymerize the monomer. Specific examples of organic solvents used in polymerization include toluene, benzene, THF, diethyl ether, and dioxane. Specific examples of polymerization initiators include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The reaction temperature is preferably 50 to 100°C. The reaction time is preferably 4 to 24 hours. The acid labile group introduced into the monomer may be used as is, or may be protected or partially protected after polymerization.

[0478] 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.

[0479] 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.

[0480] [(F) Dissolution inhibitor] The chemically amplified resist composition of the present invention may further comprise a dissolution inhibitor as component (F). When the chemically amplified resist composition of the present invention is a positive-working composition, the incorporation of a dissolution inhibitor can further increase the difference in dissolution rate between exposed and unexposed areas, thereby further improving resolution.

[0481] Specific examples of the dissolution inhibitor include compounds having a molecular weight of preferably 100 to 1,000, more preferably 150 to 800, containing two or more phenolic hydroxy groups in the molecule, in which the hydrogen atoms of the phenolic hydroxy groups have been substituted with acid labile groups in an overall ratio of 0 to 100 mol %, and compounds containing carboxy groups in the molecule, in which the hydrogen atoms of the carboxy groups have been substituted with acid labile groups in an overall ratio of 50 to 100 mol %. Specific examples include compounds in which the hydrogen atoms of the hydroxyl groups or carboxyl groups of bisphenol A, trisphenol, phenolphthalein, cresol novolak, naphthalenecarboxylic acid, adamantanecarboxylic acid, or cholic acid have been substituted with acid labile groups, such as those described in paragraphs

[0155] to

[0178] of JP 2008-122932 A.

[0482] When the chemically amplified resist composition of the present invention contains a dissolution inhibitor (F), the content thereof is preferably 0 to 50 parts by mass, and more preferably 5 to 40 parts by mass, relative to 80 parts by mass of the base polymer (A). The dissolution inhibitor (F) may be used alone or in combination of two or more types.

[0483] [(G) Other ingredients] The chemically amplified resist composition of the present invention may contain, as (G) other components, a compound that decomposes in the presence of acid to generate acid (acid amplifying compound), an organic acid derivative, a fluorine-substituted alcohol, a water repellency improver, etc. 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 mass, more preferably 0 to 3 parts by mass, per 80 parts by mass of the (A) base polymer. A content within this range facilitates control of acid diffusion, and can suppress degradation of resolution and pattern shape. Examples of the organic acid derivative and fluorine-substituted alcohol include the compounds described in JP-A-2009-269953 and JP-A-2010-215608.

[0484] The water repellency improver can be used in immersion lithography without a topcoat. Preferred examples of the water repellency improver include polymers containing fluorinated alkyl groups and polymers containing a 1,1,1,3,3,3-hexafluoro-2-propanol residue with a specific structure, with those exemplified in JP-A Nos. 2007-297590 and 2008-111103 being more preferred. The water repellency improver must be soluble in an alkaline developer or an organic solvent developer. The water repellency improver having the specific 1,1,1,3,3,3-hexafluoro-2-propanol residue described above has good solubility in the developer. As a water repellency improver, polymers containing repeating units containing an amino group or an amine salt are highly effective in preventing the evaporation of acid during PEB and preventing poor opening of the hole pattern after development. When the chemically amplified resist composition of the present invention contains the water repellency improver, the content thereof is preferably 0 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, relative to 80 parts by mass of the (A) base polymer.

[0485] [Pattern formation method] When the chemically amplified resist composition of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied. For example, a pattern formation method can include a method comprising the steps of forming a resist film on a substrate using the above-mentioned chemically amplified resist composition, exposing the resist film to high-energy rays, and developing the exposed resist film using a developer.

[0486] First, the chemically amplified resist composition of the present invention is applied to a substrate for integrated circuit production (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflective coating, etc.) or a substrate for mask circuit production (Cr, CrO, CrON, MoSi2, SiO2, etc.) by an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc., to a coating thickness of 0.01 to 2.0 μm. This is then prebaked on a hot plate, preferably at 60 to 150°C for 10 seconds to 30 minutes, more preferably at 80 to 120°C for 30 seconds to 20 minutes, to form a resist film.

[0487] Next, the resist film is exposed to high-energy radiation. Examples of the high-energy radiation include ultraviolet radiation, far ultraviolet radiation, EB, EUV radiation with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. When ultraviolet radiation, far ultraviolet radiation, EUV radiation, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation are used as the high-energy radiation, the exposure dose is preferably 1 to 200 mJ / cm, either directly or using a mask for forming a desired pattern. 2 approximately, more preferably 10 to 100 mJ / cm 2 When EB is used as the high energy beam, the exposure dose is preferably 0.1 to 100 μC / cm 2 approximately, more preferably 0.5 to 50 μC / cm 2The resist composition of the present invention is particularly suitable for fine patterning using high-energy rays such as ArF excimer laser light with a wavelength of 193 nm, KrF excimer laser light with a wavelength of 248 nm, EB (electron beam), EUV (extreme ultraviolet light) with a wavelength of 3 to 15 nm, X-rays, soft X-rays, gamma rays, or synchrotron radiation.

[0488] After the exposure, PEB may be performed on a hot plate, preferably at 60 to 150° C. for 10 seconds to 30 minutes, more preferably at 80 to 120° C. for 30 seconds to 20 minutes.

[0489] After exposure or PEB, the substrate is developed using a developer such as an aqueous alkaline solution of 0.1 to 10 mass %, preferably 2 to 5 mass %, of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, or the like, for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by a conventional method such as dipping, puddling, or spraying. The irradiated portions dissolve in the developer, while the unexposed portions do not, forming the desired positive pattern on the substrate.

[0490] A negative pattern can also be obtained by using an organic solvent developer instead of the alkaline aqueous solution. Specific examples of the developer used in this case include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, and ethyl crotonate. Examples of organic solvents include methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate. These organic solvents may be used alone or in combination of two or more.

[0491] After the development is completed, rinsing may be performed. As a rinsing liquid, a solvent that is miscible with the developer but does not dissolve the resist film is preferred. As such a solvent, alcohols having 3 to 10 carbon atoms, ether compounds having 8 to 12 carbon atoms, alkanes, alkenes, alkynes having 6 to 12 carbon atoms, and aromatic solvents are preferably used.

[0492] Specific examples of the alcohol having 3 to 10 carbon atoms include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, and 3-hexanol. Examples of the alcohol include 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, and 1-octanol.

[0493] Specific examples of the ether compound having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-tert-pentyl ether, and di-n-hexyl ether.

[0494] Specific examples of the alkanes having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, cyclononane, etc. Specific examples of the alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene, etc. Specific examples of the alkynes having 6 to 12 carbon atoms include hexyne, heptine, octyne, etc.

[0495] Specific examples of the aromatic solvent include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0496] Rinsing can reduce the occurrence of resist pattern collapse and defects. Rinsing is not always necessary, and not performing rinsing can reduce the amount of solvent used.

[0497] The developed hole or trench pattern can also be shrunk using thermal flow, RELACS, or DSA. A shrink agent is applied to the hole pattern, and the diffusion of an acid catalyst from the resist film during baking causes crosslinking of the shrink agent on the surface of the resist film, resulting in adhesion of the shrink agent to the sidewalls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the baking time is preferably 10 to 300 seconds. Excess shrink agent is removed, and the hole pattern is shrunk. [Example]

[0498] The present invention will be specifically explained below with reference to Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited to the following Examples. The apparatuses used are as follows. MALDI TOF-MS: JEOL S3000

[0499] [1] Synthesis of onium salt monomers [Example 1-1] Synthesis of onium salt monomer a-1 [ka]

[0500] Under a nitrogen atmosphere, raw material SM-1 (42.5 g) and triethylamine (6.1 g) were dissolved in methylene chloride (200 g) in a reaction vessel and cooled in an ice bath. While maintaining the temperature inside the reaction vessel at 20°C or below, raw material SM-2 (6.7 g) was added dropwise. After the dropwise addition, the mixture was warmed to room temperature and aged for 4 hours. After aging, the reaction vessel was cooled in an ice bath, water was added to terminate the reaction, and a standard aqueous work-up was performed. The solvent was then distilled off, and diisopropyl ether was added to wash the residue, yielding 44.1 g of onium salt-type monomer a-1 as an oil (yield 94%). MALDI TOF-MS: POSITIVE M + 335(C 18 H 11 F4S + equivalent) NEGATIVE M - 603(C 20 H 16 F4IO7S - equivalent)

[0501] [Examples 1-2 to 1-8] Synthesis of onium salt monomers a-2 to a-8 Onium salt-type monomers a-2 to a-8 represented by the following formulae were synthesized using corresponding raw materials and known organic synthesis reactions.

[0502] [ka]

[0503] [Comparative Examples 1-1 to 1-4] Synthesis of comparative onium salt monomers ca-1 to ca-4 Comparative onium salt-type monomers ca-1 to ca-4 represented by the following formulae were synthesized using the corresponding raw materials and known organic synthesis reactions.

[0504] [ka]

[0505] [2] Synthesis of base polymer Of the monomers used in the synthesis of the base polymer, those other than the monomers a-1 to a-8 and the comparative monomers ca-1 to ca-4 are as follows.

[0506] [ka]

[0507] [ka]

[0508] [ka]

[0509] [Example 2-1] Synthesis of Polymer P-1 Under a nitrogen atmosphere, a flask was charged with 23.5 g of monomer a-1, 20.5 g of monomer b1-1, 6.0 g of monomer c-1, 1.92 g of V-601 (Fujifilm Wako Pure Chemical Industries, Ltd.), and 70 g of MEK to prepare a monomer-polymerization initiator solution. 23 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 was complete, stirring was continued for 2 hours while maintaining the temperature of the polymerization solution at 80°C, and then the mixture was cooled to room temperature. The resulting polymerization solution was added dropwise to 1500 g of vigorously stirred hexane, and the precipitated polymer was filtered off. The resulting polymer was washed twice with 300 g of hexane and then vacuum-dried at 50°C for 20 hours to obtain polymer P-1 as a white powder (yield: 48.1 g, 96%). Polymer P-1 had an Mw of 9300 and an Mw / Mn of 1.61. Note that Mw was a value measured in terms of polystyrene by GPC using DMF as a solvent.

[0510] [ka]

[0511] [Examples 2-2 to 2-21, Comparative Examples 2-1 to 2-11] Synthesis of Polymers P-2 to P-21 and Comparative Polymers CP-1 to CP-11 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.

[0512] [Table 1]

[0513] [Table 2]

[0514] [3] Preparation of chemically amplified resist composition [Examples 3-1 to 3-21, Comparative Examples 3-1 to 3-11] Predetermined components selected from the base polymers of the present invention (P-1 to P-21), comparative base polymers (CP-1 to CP-11), acid generators (PAG-1, PAG-2), and quenchers (SQ-1 to SQ-3, AQ-1) were dissolved in a solvent containing 0.01 mass% of FC-4430 (manufactured by 3M) as a surfactant in the compositions shown in Tables 3 and 4 below to prepare solutions, which were then filtered through a 0.2 μm Teflon (registered trademark) filter to prepare chemically amplified resist compositions (R-1 to R-21, CR-1 to CR-11).

[0515] [Table 3]

[0516] [Table 4]

[0517] In Tables 3 and 4, the solvents, quenchers (SQ-1 to SQ-3, AQ-1) and acid generators (PAG-1, PAG-2) are as follows. Solvent: PGMEA (propylene glycol monomethyl ether acetate) EL (Ethyl lactate) DAA (diacetone alcohol)

[0518] Quencher: SQ-1 to SQ-3, AQ-1 [ka]

[0519] Acid generator: PAG-1, PAG-2 [ka]

[0520] [4] EUV Lithography Evaluation (1) [Examples 4-1 to 4-21, Comparative Examples 4-1 to 4-11] Each chemically amplified resist composition (R-1 to R-21, CR-1 to CR-11) 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 NXE3300 (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.

[0521] The obtained LS pattern was observed with a critical dimension SEM (CG6300) manufactured by Hitachi High-Technologies Corporation, and the sensitivity, EL, LWR, DOF, and collapse limit were evaluated according to the following methods. The results are shown in Tables 5 and 6.

[0522] [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.

[0523] [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

[0524] [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.

[0525] [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.

[0526] [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.

[0527] [Table 5]

[0528] [Table 6]

[0529] The results shown in Tables 5 and 6 demonstrate that chemically amplified resist compositions using base polymers containing repeating units derived from the onium salt-type monomer of the present invention exhibit good sensitivity and excellent EL, LWR, and DOF. Furthermore, the collapse limit value was small, demonstrating resistance to pattern collapse even in fine pattern formation. This demonstrates that the chemically amplified resist composition of the present invention is suitable as a material for EUV lithography. On the other hand, the comparative examples that did not use the onium salt-type monomer of the present invention all exhibited poor performance in sensitivity, EL, LWR, DOF, and pattern collapse.

[0530] [5] EUV Lithography Evaluation (2) [Examples 5-1 to 5-21, Comparative Examples 5-1 to 5-11] Each chemically amplified resist composition (R-1 to R-21, CR-1 to CR-11) shown in Tables 3 and 4 was spin-coated onto a Si substrate with a 20 nm thick silicon-containing spin-on hard mask (SHB-A940, manufactured by Shin-Etsu Chemical Co., Ltd.) (43 wt% silicon content) and pre-baked at 105°C for 60 seconds using a hot plate to produce a 50 nm thick resist film. This was then exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple-pole illumination, 46 nm pitch on the wafer, +20% bias hole pattern mask), subjected to PEB for 60 seconds using a hot plate at the temperatures shown in Tables 7 and 8, and developed for 30 seconds in a 2.38 wt% TMAH aqueous solution to form a 23 nm hole pattern.

[0531] Using a critical dimension SEM (CG6300) manufactured by Hitachi High-Technologies Corporation, 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 standard deviation (σ) calculated from the results was tripled (3σ) to give the coefficient of dimension variation (CDU). The results are shown in Tables 7 and 8.

[0532] [Table 7]

[0533] [Table 8]

[0534] The results shown in Tables 7 and 8 confirm that the chemically amplified resist compositions of the present invention have good sensitivity and excellent CDU. On the other hand, the comparative examples that did not use the onium salt-type monomer of the present invention were all inferior in sensitivity and CDU.

[0535] [6] Dry etching resistance evaluation [Examples 6-1 to 6-21, Comparative Examples 6-1 to 6-11] 2 g of each of the polymers shown in Tables 1 and 2 (polymers P-1 to P-21, comparative polymers CP-1 to CP-11) was dissolved in 10 g of cyclohexanone and filtered through a 0.2 μm filter. The polymer solution was spin-coated onto a Si substrate to form a film with a thickness of 300 nm, which was then evaluated under the following conditions.

[0536] Etching test with CHF3 / CF4 gas: The difference in film thickness of the polymer film before and after etching was determined using a dry etching apparatus TE-8500P manufactured by Tokyo Electron Limited. The etching conditions are as follows: Chamber pressure 40Pa RF power 1000W Gap 9mm CHF3 gas flow rate: 30 mL / min CF4 gas flow rate: 30 mL / min Ar gas flow rate: 100 mL / min Time 60sec

[0537] In this evaluation, a film with a small difference in film thickness, that is, a film with a small reduction in film thickness, indicates high etching resistance.

[0538] The results of dry etching resistance are shown in Tables 9 and 10.

[0539] [Table 9]

[0540] [Table 10]

[0541] The results shown in Tables 9 and 10 confirm that the polymers of the present invention have excellent dry etching resistance against CHF3 / CF4-based gases. On the other hand, all of the comparative examples that did not use the onium salt-type monomer of the present invention were poor in dry etching resistance.

[0542] This specification includes the following inventions.

[0543] [1]: An onium salt type monomer represented by the following formula (a): [ka] (In the formula, n1 is 0 or 1. n2 is 1, 2, 3, or 4. n3 is 0, 1, or 2. However, when n1 is 0, 1≦n2+n3≦3, and when n1 is 1, 1≦n2+n3≦5. n4 is 0 or 1. n5 is 0, 1, 2, 3, or 4. n6 is 0, 1, or 2. However, when n4 is 0, 0≦n5+n6≦4, and when n4 is 1, 0≦n5+n6≦6. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R AL is an acid labile group. R 1 is a halogen atom other than an iodine atom, a nitro group, a cyano group, a hydroxy group, an alkoxycarbonyl 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, or a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom. When n3 is 2, each R 1 may be the same or different, and two 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 halogen atom other than a fluorine atom, a nitro group, a cyano group, a hydroxy group, an alkoxycarbonyl 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, or a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom. When n6 is 2, each R 2 may be the same or different, and two R 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R F is a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a fluorinated saturated hydrocarbyloxy group having 1 to 6 carbon atoms, or a fluorinated saturated hydrocarbylthio group having 1 to 6 carbon atoms. When n5 is 2, 3, or 4, each R F may be the same as or different from each other. L A and L B are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, an amide bond, a sulfonate amide bond, a carbonate bond or a carbamate bond. X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. Z + is an onium cation.

[0544] [2]: The onium salt monomer according to the above [1], which is represented by the following formula (a1): [ka] (In the formula, n1~n6, R A , R AL , R 1 , R 2 , R F , L A , and Z + is the same as above.)

[0545] [3]: The onium salt monomer according to the above [1] or [2], which is represented by the following formula (a2): [ka] (In the formula, n1~n6, R A , R AL , R 1 , R 2 , R F , and Z + is the same as above.)

[0546] [4]: Furthermore, the R AL The onium salt monomer according to any one of the above [1] to [3], wherein the structure of the acid labile group represented by the following formula (AL-1) or (AL-2) is [ka] (Wherein, n6 is 0 or 1. n7 is 0 or 1. R L1 , R L2 and R L3are each independently a hydrocarbyl group having 1 to 12 carbon atoms, in which some of the -CH2- groups in the hydrocarbyl group may be substituted with -O- or -S-, and when the hydrocarbyl group contains an aromatic ring, some or all of the hydrogen atoms in the aromatic ring may be substituted with a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 4 carbon atoms which may contain a halogen atom, or an alkoxy group having 1 to 4 carbon atoms which may contain a halogen atom. L1 and R L2 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded, and some of the -CH2- in the ring may be substituted with -O- or -S-. R L4 and R L5 R are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a hydrogen atom or a halogen atom. L6 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom, and a portion of the -CH2- in the hydrocarbyl group may be substituted with -O- or -S-. L5 and R L6 are bonded to each other and the carbon atoms to which they are bonded and L C may form a heterocyclic group having 3 to 20 carbon atoms together, and some of the -CH2- in the heterocyclic group may be substituted with -O- or -S-. L C is —O— or —S—. * represents a bond to the adjacent -O-.)

[0547] [5]:Z above + The onium salt monomer according to any one of the above [1] to [4], wherein the onium cation represented by the following formula (Z-1) is a sulfonium cation represented by the following formula (Z-1) or an iodonium cation represented by the following formula (Z-2): [ka] (In the formula, R ct1 ~R ct5are 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.

[0548] [6]:Z above + The onium salt monomer according to any one of the above [1] to [4], wherein the onium cation represented by the formula: is a sulfonium cation represented by the following formula (Z-3): [ka] (Wherein, m1 is 0 or 1. m2 is 0 or 1. m3 is 0 or 1. m4 is 0, 1, 2, 3 or 4. m5 is 0, 1, 2, 3 or 4. m6 is 0, 1, 2, 3, 4, 5 or 6. m7 is 0, 1, 2, 3, 4, 5 or 6. m8 is 0, 1 or 2. m9 is 0, 1 or 2. m10 is 0, 1 or 2. m11 is 0 or 1. m12 is 0, 1, 2, 3 or 4. m13 is 0, 1 or 2. m14 is 0, 1 or 2. However, when m1 is 0, 0≦m6+m9≦4, and when m1 is 1, 0≦m6+m9≦6. When m2 is 0, 0≦m7+m10≦4, and when m2 is 1, 0≦m7+m10≦6. When m3 is 0, 1≦m4+m5+m8+m14≦4, and when m3 is 1, 1≦m4+m5+m8+m14≦6. When m11 is 0, 0≦m12+m13≦4, and when m11 is 1, 0≦m12+m13≦6. Also, m4+m12≧1. R F1 ~R F3 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. 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 RF3 may be the same or different from each other. R ct6 ~R ct9 is a halogen atom other than an iodine atom or a 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. 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 ct9 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. In addition, S in the sulfonium cation + The aromatic rings directly bonded to S + may form a ring together with L D and L E 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. X L2 is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom.

[0549] [7]: A monomeric photoacid generator comprising the onium salt monomer according to any one of [1] to [6] above.

[0550] [8]: A polymer characterized by containing a repeating unit derived from the onium salt type monomer according to any one of the above [1] to [6].

[0551] [9]: The polymer according to the above [8], further comprising a repeating unit represented by the following formula (b1) or (b2): [ka] (In the formula, 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, *-C(=O)-OX 11 - or *-C(=O)-NH-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, *-C(=O)-O- or *-C(=O)-NH-. * indicates a bond to a carbon atom in the main chain. R 11 represents 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. AL 1and AL 2 are each independently an acid labile group. a1 is 0, 1, 2, 3 or 4.

[0552]

[10] : The polymer according to the above [8] or [9], further comprising a repeating unit represented by the following formula (b3): [ka] (In the formula, b1 is 0 or 1. When b1 is 0, b2 is 0, 1, 2, or 3, and when b1 is 1, b2 is 0, 1, 2, 3, 4, or 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. R 12 and R 13 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 12 and R 13 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 14 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 14A )(R 14B ) R 14A and R 14B are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms. When b2 is 2 or more, multiple R 14 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached. 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. 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 an aromatic ring.)

[0553]

[11] : The polymer according to any one of the above [8] to

[10] , further comprising a repeating unit represented by the following formula (c): [ka] (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. R 21 represents a halogen atom, a nitro group, a cyano 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 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 1, 2, 3, or 4. c2 is 0, 1, 2, or 3, provided that 1≦c1+c2≦5.

[0554]

[12] : The polymer according to any one of the above [8] to

[11] , further comprising a repeating unit represented by the following formula (d): [ka] (In the formula, R Ais a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z 1 represents a single bond, a phenylene group, a naphthylene group, *-C(=O)-OZ 11 -or*-C(=O)-NH-Z 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. * represents a bond to a carbon atom in the main chain. Z 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. R 31 is a hydrogen atom, or a group having 1 to 20 carbon atoms containing at least one structure selected from 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)-).

[0555]

[13] : (A) A chemically amplified resist composition comprising a base polymer containing the polymer according to any one of [8] to

[12] above.

[0556]

[14] : The chemically amplified resist composition according to the above

[13] , further comprising at least one selected from the group consisting of (B) an organic solvent, (C) a quencher, (D) an acid generator, (E) a surfactant, and (F) a dissolution inhibitor.

[0557]

[15] : A pattern forming method comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition according to

[13] or

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

[0558]

[16] : The pattern forming method according to the above

[15] , wherein the high-energy beam is an ArF excimer laser beam having a wavelength of 193 nm, a KrF excimer laser beam having a wavelength of 248 nm, an electron beam, or extreme ultraviolet light having a wavelength of 3 to 15 nm.

[0559] The present invention is not limited to the above-described embodiments, which 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 provides similar effects is included within the technical scope of the present invention.

Claims

1. An onium salt type monomer characterized by being represented by the following formula (a): 【Chemistry 1】 (In the formula, n1 is 0 or 1. n2 is 1, 2, 3, or 4. n3 is 0, 1, or 2. However, when n1 is 0, 1≦n2+n3≦3, and when n1 is 1, 1≦n2+n3≦5. n4 is 0 or 1. n5 is 0, 1, 2, 3, or 4. n6 is 0, 1, or 2. However, when n4 is 0, 0≦n5+n6≦4, and when n4 is 1, 0≦n5+n6≦6. R Ａ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ＡＬ is an acid labile group. R １ is a halogen atom other than an iodine atom, a nitro group, a cyano group, a hydroxy group, an alkoxycarbonyl 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, or a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom. １ may be the same or different, and two 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 halogen atom other than a fluorine atom, a nitro group, a cyano group, a hydroxy group, an alkoxycarbonyl 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, or a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom. ２ may be the same or different, and two R ２ may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R Ｆ is a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a fluorinated saturated hydrocarbyloxy group having 1 to 6 carbon atoms, or a fluorinated saturated hydrocarbylthio group having 1 to 6 carbon atoms. When n5 is 2, 3, or 4, each R Ｆ may be the same as or different from each other. L Ａ and L Ｂ are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, an amide bond, a sulfonate amide bond, a carbonate bond or a carbamate bond. X Ｌ is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. Z ＋ is an onium cation.

2. 2. The onium salt monomer according to claim 1, which is represented by the following formula (a1): 【Chemistry 2】 (In the formula, n1 to n6, R Ａ , R ＡＬ , R １ , R ２ , R Ｆ , L Ａ , and Z ＋ is the same as above.)

3. The onium salt monomer according to claim 2, which is represented by the following formula (a2): 【Transformation 3】 (In the formula, n1 to n6, R Ａ , R ＡＬ , R １ , R ２ , R Ｆ , and Z ＋ is the same as above.)

4. Furthermore, the R ＡＬ The onium salt monomer according to claim 1, wherein the structure of the acid labile group represented by the following formula (AL-1) or (AL-2) is 【Chemistry 4】 (Wherein, n6 is 0 or 1. n7 is 0 or 1. R Ｌ１ , R Ｌ２ and R Ｌ３ are each independently a hydrocarbyl group having 1 to 12 carbon atoms, and the —CH ２ A part of - may be substituted with -O- or -S-, and when the hydrocarbyl group contains an aromatic ring, a part or all of the hydrogen atoms of the aromatic ring may be substituted with a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 4 carbon atoms which may contain a halogen atom, or an alkoxy group having 1 to 4 carbon atoms which may contain a halogen atom. Ｌ１ and R Ｌ２ may be bonded to each other to form a ring together with the carbon atoms to which they are attached, and the —CH ２ A portion of - may be substituted with -O- or -S-. R Ｌ４ and R Ｌ５ are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a hydrogen atom or a halogen atom. Ｌ６ is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom, and the —CH ２ A part of - may be substituted with -O- or -S-. Ｌ５ and R Ｌ６ are bonded to each other and the carbon atom to which they are bonded and L Ｃ may form a heterocyclic group having 3 to 20 carbon atoms together with the —CH ２ A portion of - may be substituted with -O- or -S-. L Ｃ is —O— or —S—. * represents a bond to the adjacent —O—.)

5. Said Z ＋ is a sulfonium cation represented by the following formula (Z-1) or an iodonium cation represented by the following formula (Z-2): 【Transformation 5】 (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.)

6. Said Z ＋ The onium salt monomer according to claim 1, wherein the onium cation represented by the formula (Z-3) is a sulfonium cation represented by the formula (Z-3): 【Transformation 6】 (Wherein, m1 is 0 or 1. m2 is 0 or 1. m3 is 0 or 1. m4 is 0, 1, 2, 3 or 4. m5 is 0, 1, 2, 3 or 4. m6 is 0, 1, 2, 3, 4, 5 or 6. m7 is 0, 1, 2, 3, 4, 5 or 6. m8 is 0, 1 or 2. m9 is 0, 1 or 2. m10 is 0, 1 or 2. m11 is 0 or 1. m12 is 0, 1, 2, 3 or 4. m13 is 0, 1 or 2. m14 is 0, 1 or 2. However, when m1 is 0, 0≦m6+m9≦4, and when m1 is 1, 0≦m6+m9≦6. When m2 is 0, 0≦m7+m10≦4, and when m2 is 1, 0≦m7+m10≦6. When m3 is 0, 1≦m4+m5+m8+m14≦4, and when m3 is 1, 1≦m4+m5+m8+m14≦6. When m11 is 0, 0≦m12+m13≦4, and when m11 is 1, 0≦m12+m13≦6. Also, m4+m12≧1. R Ｆ１ ~R Ｆ３ 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. 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. R ｃｔ６ ~R ｃｔ９ is a halogen atom other than an iodine atom or a 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. 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 bonded, 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 ｃｔ９ may be bonded to each other to form a ring together with the carbon atoms to which they are attached. In addition, S in the sulfonium cation ＋ The aromatic rings directly bonded to S ＋ may form a ring together with L Ｄ and L Ｅ 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. X Ｌ２ is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom.

7. A monomeric photoacid generator comprising the onium salt monomer according to any one of claims 1 to 6.

8. A polymer comprising a repeating unit derived from the onium salt type monomer according to any one of claims 1 to 6.

9. The polymer according to claim 8, further comprising a repeating unit represented by the following formula (b1) or (b2): 【Transformation 7】 (In the formula, 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, *—C(═O)—O—X １１ - or *-C(=O)-NH-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, *-C(=O)-O- or *-C(=O)-NH-. * indicates a bond to a carbon atom in the main chain. R １１ represents 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. AL １ and AL ２ are each independently an acid labile group. a1 is 0, 1, 2, 3 or 4.

10. The polymer according to claim 8, further comprising a repeating unit represented by the following formula (b3): 【Transformation 8】 (In the formula, b1 is 0 or 1. When b1 is 0, b2 is 0, 1, 2, or 3, and when b1 is 1, b2 is 0, 1, 2, 3, 4, or 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. R １２ and R １３ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. １２ and R １３ may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R １４ 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 １４Ａ ) (R １４Ｂ ) R １４Ａ and R １４Ｂ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms. When b2 is 2 or more, a plurality of R １４ may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached. 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 an aromatic ring.)

11. The polymer according to claim 8, further comprising a repeating unit represented by the following formula (c): 【Chemistry 9】 (In the formula, R Ａ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y １ is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. R ２１ represents a halogen atom, a nitro group, a cyano 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 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 1, 2, 3, or 4. c2 is 0, 1, 2, or 3, provided that 1≦c1+c2≦5.

12. The polymer according to claim 8, further comprising a repeating unit represented by the following formula (d): 【Chemistry 10】 (In the formula, R Ａ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z １ represents a single bond, a phenylene group, a naphthylene group, *-C(=O)-O-Z １１ - or *-C(=O)-NH-Z 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. * represents a bond to a carbon atom in the main chain. Z 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. R ３１ is a hydrogen atom, or a group having 1 to 20 carbon atoms containing at least one structure selected from 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)-O-C(=O)-).

13. A chemically amplified resist composition comprising (A) a base polymer containing the polymer according to claim 8.

14. 14. The chemically amplified resist composition according to claim 13, further comprising at least one selected from the group consisting of (B) an organic solvent, (C) a quencher, (D) an acid generator, (E) a surfactant, and (F) a dissolution inhibitor.

15. 14. A pattern forming method comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition according to claim 13; exposing the resist film to high-energy rays; and developing the exposed resist film using a developer.

16. 16. The pattern formation method according to claim 15, wherein the high-energy beam is ArF excimer laser light having a wavelength of 193 nm, KrF excimer laser light having a wavelength of 248 nm, an electron beam, or extreme ultraviolet light having a wavelength of 3 to 15 nm.

Images