Onium salt, chemically amplified resist composition and pattern forming method

Abstract

The invention relates to an onium salt, a chemically amplified resist composition and a pattern forming method. The present invention addresses the problem of providing: an onium salt which is used in a chemically amplified resist composition having excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance such as exposure latitude (EL) and LWR in optical lithography using high-energy rays; a chemically amplified resist composition containing the onium salt as a photoacid generator; and a pattern forming method using the chemically amplified resist composition. [Solution] An onium salt represented by formula (1). In the # imgabs0 # formula, one of R13 and R14 is a group having a partial structure represented by formula (1a). # imgabs1 #

Description

Technical Field

[0001] The present invention relates to an onium salt, a chemically amplified resist composition and a pattern forming method. Background Art

[0002] In recent years, with the increasing integration and speed of LSIs and the resulting demand for more precise patterning, far-ultraviolet (UV) lithography and extreme ultraviolet (EUV) lithography have been recognized as promising next-generation microfabrication technologies. Among these, optical lithography using ArF excimer lasers is essential for ultra-fine fabrication below 0.13μm.

[0003] ArF lithography was partially adopted in device fabrication starting with the 130nm node, and became the primary lithography technology starting with the 90nm node. Regarding the subsequent 45nm node, 157nm lithography using F2 lasers was initially considered promising, but development was delayed due to numerous issues. Consequently, ArF immersion lithography, which inserts a liquid with a higher refractive index than air, such as water, ethylene glycol, or glycerin, between the projection lens and the wafer, thereby setting the numerical aperture (NA) of the projection lens to 1.0 or higher and achieving high resolution, quickly emerged (Non-Patent Document 1) and is now in practical use. This immersion lithography requires a resist composition that is not easily eluted into water.

[0004] ArF photolithography, in order to prevent the deterioration of accurate and expensive optical system materials, requires that a small exposure can bring into play the high sensitivity resist composition of sufficient resolution. With regard to the method for realizing it, it is the most general to select a highly transparent person as its composition in a wavelength of 193nm. For example, at base polymer, someone proposes: polyacrylic acid and derivatives thereof, norbornene-maleic anhydride interactive polymer, polynorbornene, ring-opening metathesis polymer, ring-opening metathesis polymer hydride etc., and aspect the transparency that improves resin monomer, has obtained a certain degree of achievement.

[0005] In recent years, while positive-tone resists developed with alkaline aqueous solutions have attracted attention, negative-tone resists developed with organic solvents have also received attention. In order to use negative-tone exposure to analyze very fine hole patterns that cannot be achieved with positive-tone exposure, a high-resolution positive-tone resist composition is used and developed with an organic solvent to form a negative pattern. In addition, research is underway to achieve double the resolution by combining a second development process of alkaline aqueous solution development and organic solvent development. As for ArF resist compositions for negative-tone development with organic solvents, known positive-tone ArF resist compositions can be used, and pattern formation methods using them are described in Patent Documents 1 to 3.

[0006] To accommodate the rapid miniaturization in recent years, process technology advances have led to the development of resist compositions. Various photoacid generators have been explored, with sulfonium salts composed of triphenylsulfonium cations and perfluoroalkanesulfonate anions generally used. However, the acid generated, perfluoroalkanesulfonic acid, particularly perfluorooctanesulfonic acid (PFOS), faces concerns about its poor decomposition, bioaccumulation, and toxicity, making it difficult to use in resist compositions. Currently, photoacid generators that generate perfluorobutanesulfonic acid are used. However, when used in resist compositions, the generated acid diffuses widely, making it difficult to achieve high resolution. To address this issue, various partially fluorinated alkanesulfonic acids and their salts have been developed. For example, Patent Document 1 describes a photoacid generator that generates α,α-difluoroalkanesulfonic acid upon exposure. Specifically, it describes a photoacid generator that generates di(4-tert-butylphenyl)iodonium 1,1-difluoro-2-(1-naphthyl)ethanesulfonate and α,α,β,β-tetrafluoroalkanesulfonic acid. However, although these have reduced fluorine substitution rates, they lack decomposable substituents such as ester structures, making them insufficient from the perspective of environmental safety due to their ease of decomposition. Furthermore, there are limitations on molecular design for varying the size of alkanesulfonic acids, and the relatively high price of fluorine-containing starting materials.

[0007] Furthermore, as circuit line widths shrink, the impact of acid diffusion on contrast degradation in resist compositions becomes more severe. This is because pattern dimensions approach the acid diffusion length, increasing the dimensional misalignment on the wafer (mask error factor (MEF)) relative to the dimensional misalignment of the mask, leading to reduced mask fidelity and degraded pattern rectangularity. Therefore, to fully realize the benefits of shorter wavelengths and higher NA light sources, it is necessary to increase dissolution contrast or suppress acid diffusion compared to conventional materials. One improvement measure, lowering the baking temperature, reduces acid diffusion. While this improves the MEF, it inevitably results in lower sensitivity.

[0008] Introducing bulky substituents or polar groups into photoacid generators is effective in suppressing acid diffusion. Patent Document 4 describes a photoacid generator comprising 2-acyloxy-1,1,3,3,3-pentafluoropropane-1-sulfonic acid that exhibits excellent solvent solubility and stability and allows for a wide range of molecular designs. In particular, a photoacid generator comprising 2-(1-adamantyloxy)-1,1,3,3,3-pentafluoropropane-1-sulfonic acid that incorporates bulky substituents exhibits low acid diffusion. Furthermore, Patent Documents 5-7 describe photoacid generators that incorporate condensed ring lactones, sultones, and thiolactones as polar groups. While the introduction of polar groups has been shown to inhibit acid diffusion and improve performance to a certain extent, high-level control of acid diffusion is still insufficient, and overall photolithographic performance, including MEF, pattern shape, and sensitivity, remains unsatisfactory.

[0009] Introducing polar groups into the anion of a photoacid generator is effective in suppressing acid diffusion, but is disadvantageous from the perspective of solvent solubility. Patent Documents 8 and 9 attempt to improve solvent solubility by introducing alicyclic groups into the cationic portion of the photoacid generator to ensure solvent solubility. Specifically, cyclohexane rings and adamantane rings are introduced. Although the introduction of such alicyclic groups improves solubility, a certain carbon number is required to ensure solubility. As a result, the molecular structure of the photoacid generator becomes bulky, and thus, when forming fine patterns, lithography performance such as line width roughness (LWR) and dimensional uniformity (CDU) deteriorates.

[0010] Patent Document 10 also describes a photoacid generator that generates fluoroalkanesulfonic acid, whose anion has an aromatic condensed ring derived from anthracene. While this has been shown to improve lithographic performance to some extent, the lack of rigidity of the alkanesulfonic acid structure, coupled with the recent continued regulation of organic fluorine compounds that are PFAS, raises concerns about their impact on the environment and human health. To meet the demand for further miniaturization, the development of novel photoacid generators is crucial. There is a desire for photoacid generators that effectively control acid diffusion, exhibit excellent solvent solubility, and improve lithographic performance.

[0011] Prior art literature

[0012] Patent Literature

[0013] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-281974

[0014] [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-281975

[0015] [Patent Document 3] Japanese Patent No. 4554665

[0016] [Patent Document 4] Japanese Patent Application Laid-Open No. 2007-145797

[0017] [Patent Document 5] Japanese Patent No. 5061484

[0018] [Patent Document 6] Japanese Patent Application Laid-Open No. 2016-147879

[0019] [Patent Document 7] Japanese Patent Application Laid-Open No. 2015-63472

[0020] [Patent Document 8] Japanese Patent No. 5573098

[0021] [Patent Document 9] Japanese Patent No. 6461919

[0022] [Patent Document 10] Japanese Patent No. 7109178

[0023] Non-patent literature

[0024] [Non-patent document 1] Journal of Photopolymer Science and Technology, Vol. 17, No. 4, p. 587-601 (2004) Summary of the Invention

[0025] [Problems to be Solved by the Invention]

[0026] In response to recent demands for higher resolution in resist patterns, resist compositions using known onium salt-type photoacid generators cannot sufficiently suppress acid diffusion, resulting in degradation of lithography performance such as contrast, MEF, and LWR.

[0027] The present invention has been made in view of the above-mentioned circumstances, and its object is to provide an onium salt for use in a chemically amplified resist composition that has excellent solvent solubility, high sensitivity, high contrast, and excellent lithographic performance such as exposure latitude (EL) and LWR, particularly in optical lithography using high-energy radiation such as KrF excimer laser, ArF excimer laser, electron beam (EB), and EUV; a chemically amplified resist composition containing the onium salt as a photoacid generator; and a pattern forming method using the chemically amplified resist composition.

[0028] [Methods for solving the problem]

[0029] The inventors of the present application have conducted extensive research to achieve the aforementioned objectives, and as a result, have reached the following findings, leading to the completion of the present invention: an onium salt containing a sulfonic acid anion having a condensed ring structure with a substituent and an aromatic sulfonic acid structure has excellent solvent solubility. A chemically amplified resist composition using this salt as a photoacid generator exhibits high sensitivity and high contrast, is extremely effective in suppressing acid diffusion, and exhibits excellent lithographic performance for EL, LWR, and the like, making it extremely effective in forming fine patterns.

[0030] That is, the present invention provides the following onium salt, chemically amplified resist composition, and pattern forming method.

[0031] 1. An onium salt represented by the following formula (1).

[0032] [Chemistry 1]

[0033]

[0034] Where R 1 ~R 12 Each independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom.

[0035] R 13 and R14 One of them is a group having a partial structure represented by the following formula (1a), and the other is a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom.

[0036] Again, R 1 ~R 14 At least two of them may be bonded to each other and form a ring together with the carbon atoms to which they are bonded, or form a ring together with the carbon atoms to which they are bonded and the carbon atoms between them.

[0037] Z + Onium cation.

[0038] [Chemistry 2]

[0039]

[0040] In the formula, m1 is 0 or 1. m2 is an integer from 0 to 4 when m1 is 0, and an integer from 0 to 6 when m1 is 1. m3 is an integer from 0 to 3 when m1 is 0, and an integer from 0 to 5 when m1 is 1. However, m2+m3 is 0 to 4 when m1 is 0, and 0 to 6 when m1 is 1.

[0041] R F It is a fluorine atom, a fluorinated alkyl group having 1 to 6 carbon atoms, a fluorinated alkoxy group having 1 to 6 carbon atoms, or a fluorinated alkylthio group having 1 to 6 carbon atoms.

[0042] R 15 is a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom, and when m3 is 2 or more, multiple R 15 They may also bond to each other and to the carbon atoms to which they are bonded to form a ring.

[0043] L A and L B are each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonate bond, a sulfonamide bond, a carbonate bond or a carbamate bond.

[0044] X L It is a single bond or a alkylene group having 1 to 40 carbon atoms which may contain a heteroatom.

[0045] 2. The onium salt according to 1., which is represented by the following formula (1A).

[0046] [Chemistry 3]

[0047]

[0048] Where R 1 ~R 13 、R 15 、L A 、X L 、R F, m1~m3 and Z + Same as above.

[0049] 3. The onium salt according to 2., which is represented by the following formula (1B).

[0050] [Chemistry 4]

[0051]

[0052] Where R 5 、R 10 ~R 13 、R 15 、L A 、X L 、R F , m1~m3 and Z + Same as above.

[0053] m4 and m5 are each independently an integer of 0-4.

[0054] R 16 and R 17 are independently a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. 16 They may also be bonded to each other and form a ring together with the carbon atoms to which they are bonded, or form a ring together with the carbon atoms to which they are bonded and the carbon atoms between them. When m5 is 2 or more, multiple R 17 They may also be bonded to each other and to form a ring together with the carbon atoms to which they are bonded, or to form a ring together with the carbon atoms to which they are bonded and the carbon atoms between them.

[0055] 4. The onium salt according to 3., which is represented by the following formula (1C).

[0056] [Chemistry 5]

[0057]

[0058] Where R 5 、R 10 ~R 13 、R 16 、R 17 、L A 、X L , m4, m5 and Z + Same as above.

[0059] 5. The onium salt according to any one of 1. to 4., wherein Z + It is a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2).

[0060] [Chemistry 6]

[0061]

[0062] Where R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbon group having 1 to 30 carbon atoms which may contain a hetero atom. ct1 and R ct2 They may also bond to each other and to the sulfur atom to which they are bonded to form a ring.

[0063] 6. A photoacid generator comprising the onium salt according to any one of 1. to 5.

[0064] 7. A chemically amplified resist composition comprising the photoacid generator according to 6.

[0065] 8. The chemically amplified resist composition according to 7., comprising:

[0066] The base polymer contains a repeating unit represented by the following formula (a1).

[0067] [Chemistry 7]

[0068]

[0069] Where R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0070] X 1 is a single bond, phenylene, naphthylene or *-C(=O)-OX 11 -, and the phenylene group or naphthylene group may be substituted with an alkoxy group having 1 to 10 carbon atoms or a halogen atom which may contain a fluorine atom. 11 It is a saturated alkylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group. The saturated alkylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. * represents an atomic bond to a carbon atom in the main chain.

[0071] AL 1 It is an acid-labile group.

[0072] 9. The chemically amplified resist composition according to 8., wherein the base polymer contains a repeating unit represented by the following formula (a2).

[0073] [Chemistry 8]

[0074]

[0075] Where R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0076] X 2It is a single bond or *-C(=O)-O-. * represents an atomic bond to a carbon atom of the main chain.

[0077] R 21 It is a halogen atom, a cyano group, a hydrocarbon group having 1 to 20 carbon atoms which may contain hetero atoms, a hydrocarbonoxy group having 1 to 20 carbon atoms which may contain hetero atoms, a hydrocarboncarbonyl group having 2 to 20 carbon atoms which may contain hetero atoms, a hydrocarboncarbonyloxy group having 2 to 20 carbon atoms which may contain hetero atoms, or a hydrocarbonoxycarbonyl group having 2 to 20 carbon atoms which may contain hetero atoms.

[0078] AL 2 It is an acid-labile group.

[0079] a is an integer from 0 to 4.

[0080] 10. The chemically amplified resist composition according to 8. or 9., wherein the base polymer contains a repeating unit represented by the following formula (b1) or (b2).

[0081] [Chemistry 9]

[0082]

[0083] Where R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0084] Y 1 It is a single bond or *-C(=O)-O-. * represents an atomic bond to a carbon atom of the main chain.

[0085] R 31 A group having 1 to 20 carbon atoms, or a structure containing at least one selected from the group consisting of a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-).

[0086] R 32 It is a halogen atom, a hydroxyl group, a nitro group, a hydrocarbon group having 1 to 20 carbon atoms which may contain heteroatoms, a hydrocarbonoxy group having 1 to 20 carbon atoms which may contain heteroatoms, a hydrocarboncarbonyl group having 2 to 20 carbon atoms which may contain heteroatoms, a hydrocarboncarbonyloxy group having 2 to 20 carbon atoms which may contain heteroatoms, or a hydrocarbonoxycarbonyl group having 2 to 20 carbon atoms which may contain heteroatoms.

[0087] b is an integer from 1 to 4. c is an integer from 0 to 4. However, 1≤b+c≤5.

[0088] 11. The chemically amplified resist composition according to any one of 8. to 10., wherein the base polymer contains at least one selected from the group consisting of a repeating unit represented by the following formula (c1), a repeating unit represented by the following formula (c2), a repeating unit represented by the following formula (c3), and a repeating unit represented by the following formula (c4).

[0089] [Chemistry 10]

[0090]

[0091] Where R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0092] Z 1 is a single bond or a phenylene group.

[0093] Z 2 *-C(=O)-OZ 21 -, *-C(=O)-NH-Z 21 -or*-OZ 21 -.Z 21 It is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining them, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group.

[0094] Z 3 are independently a single bond, a phenylene group, a naphthylene group or *-C(=O)-OZ 31 -.Z 31 It is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the aliphatic hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond or a lactone ring.

[0095] Z 4 are independently a single bond, **-Z 41 -C(=O)-O-, **-C(=O)-NH-Z 41 -or**-OZ 41 -.Z 41 It is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom.

[0096] Z 5 are independently a single bond, *-Z 51 -C(=O)-O-, *-C(=O)-NH-Z 51 -or*-OZ 51 -.Z 51 It is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom.

[0097] Z 6is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, phenylene substituted with trifluoromethyl, *-C(=O)-OZ 61 -, *-C(=O)-N(H)-Z 61 -or*-OZ 61 -.Z 61 It is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group.

[0098] * indicates an atomic bond to a carbon atom in the main chain. ** indicates an atomic bond to Z 3 atomic bonds.

[0099] R 41 and R 42 are each independently a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 41 and R 42 They may also bond to each other and to the sulfur atom to which they are bonded to form a ring.

[0100] L 1 It is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond or a carbamate bond.

[0101] Rf 1 and Rf 2 Each independently represents a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms.

[0102] Rf 3 and Rf 4 Each independently represents a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms.

[0103] Rf 5 and Rf 6 are independently a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms. 5 and Rf 6 It cannot be a hydrogen atom at the same time.

[0104] M - It is a non-nucleophilic relative ion.

[0105] A + Onium cation.

[0106] d is an integer from 0 to 3.

[0107] 12. The chemically amplified resist composition according to any one of 7. to 11., further comprising an organic solvent.

[0108] 13. The chemically amplified resist composition according to any one of 7. to 12., further comprising a quencher.

[0109] 14. The chemically amplified resist composition according to any one of 7. to 13., further comprising a photoacid generator other than the photoacid generator according to 6.

[0110] 15. The chemically amplified resist composition according to any one of 7. to 14., further comprising a surfactant.

[0111] 16. A pattern forming method comprising the following steps:

[0112] Using the chemically amplified resist composition according to any one of 7. to 15. to form a resist film on a substrate, exposing the resist film to high-energy radiation, and

[0113] The exposed resist film is developed using a developer.

[0114] 17. The pattern forming method according to 16., wherein the high-energy radiation is KrF excimer laser, ArF excimer laser, EB or EUV with a wavelength of 3 to 15 nm.

[0115] [Effects of the Invention]

[0116] When patterning is performed using a chemically amplified resist composition containing the onium salt of the present invention as a photoacid generator, it exhibits high sensitivity, excellent acid diffusion suppression capability, improved MEF, LWR and other lithographic performances, and can suppress resist pattern collapse during fine pattern formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0117] [ Figure 1 ]NMR spectrum of the onium salt PAG-1 synthesized in Example 1-1 ( 1 H-NMR / DMSO-d6). DETAILED DESCRIPTION

[0118] The present invention is described in detail below. In the following description, depending on the structure represented by the chemical formula, asymmetric carbon atoms may exist, and enantiomers and diastereomers may exist. In such cases, these isomers are represented by a single general formula. These isomers may be used alone or as a mixture of two or more.

[0119] [Onium salt]

[0120] The onium salt of the present invention is represented by the following formula (1).

[0121] [Chemistry 11]

[0122]

[0123] In formula (1), R 1 ~R 12Each of R is independently a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 13 and R 14 One of them is a group having a partial structure represented by formula (1a) described later, and the other is a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom.

[0124] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples 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 eicosyl; cyclic saturated hydrocarbon groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated hydrocarbon groups having 3 to 20 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 20 carbon atoms, such as phenyl and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and combinations thereof. Among these, aryl groups are preferred. Furthermore, part or all of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and part of the -CH2- of the hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, the hydrocarbon group may contain a hydroxyl group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like.

[0125] Again, R 1 ~R 14At least two of the -CH2- radicals may be bonded to each other and form a ring together with the carbon atoms to which they are bonded, or together with the carbon atoms to which they are bonded and the carbon atoms between them. Specific examples of the ring formed in this case include alicyclic rings such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, norbornane, and adamantane, and aromatic rings such as benzene, naphthalene, and anthracene. Furthermore, some or all of the hydrogen atoms in the aforementioned rings may be substituted with groups containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms, and some of the -CH2- radicals in the aforementioned rings may be substituted with groups containing heteroatoms such as oxygen, sulfur, or nitrogen atoms. As a result, the rings may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonate bonds, carbonate bonds, lactone rings, sultone rings, carboxylic anhydride (-C(=O)-OC(=O)-), or haloalkyl groups. The aforementioned rings are preferably aromatic rings, and more preferably benzene rings.

[0126] In formula (1), R 13 or R 14 Any of the groups is a group having a partial structure represented by the following formula (1a). 14 It is preferably a group having a partial structure represented by the following formula (1a).

[0127] [Chemistry 12]

[0128]

[0129] In formula (1a), m1 is 0 or 1. When m1 is 0, it is a benzene ring, and when m1 is 1, it is a naphthalene ring. From the perspective of solvent solubility, m1 is preferably a benzene ring when 0. m2 is an integer of 0 to 4 when m1 is 0, and an integer of 0 to 6 when m1 is 1. m2 is preferably 4 when m1 is 0, and preferably 4, 5, or 6 when m1 is 1. m3 is an integer of 0 to 3 when m1 is 0, and an integer of 0 to 5 when m1 is 1. However, m2+m3 is 0 to 4 when m1 is 0, and 0 to 6 when m1 is 1.

[0130] In formula (1a), R F R is a fluorine atom, a fluorinated alkyl group having 1 to 6 carbon atoms, a fluorinated alkoxy group having 1 to 6 carbon atoms, or a fluorinated alkylthio group having 1 to 6 carbon atoms. F Preferably, it is a fluorine atom, a trifluoromethyl group, a difluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group, a trifluoromethylthio group or a difluoromethylthio group, and more preferably a fluorine atom, a trifluoromethyl group or a trifluoromethoxy group. By containing a fluorine atom or these substituents having a fluorine atom, the acid strength of the generated acid is improved due to the electron-withdrawing effect, so the deprotection reaction of the acid-labile group such as tertiary ester or tertiary ether described later proceeds smoothly. When m2 is 2, 3 or 4, each R F They can be the same or different from each other.

[0131] In formula (1a), R 15 is a hydrocarbon group having 1 to 20 carbon atoms which may contain heteroatoms. The hydrocarbon group may be saturated or unsaturated and may be linear, branched or cyclic. Specific examples thereof include: 1 The same examples as those of the hydrocarbon groups represented are not limited thereto. When m3 is 2 or more, each R 15 They may be the same or different from each other. 15 They may also be bonded to each other and to the carbon atoms to which they are bonded to form a ring. The aforementioned ring is preferably a 5- to 8-membered ring.

[0132] In formula (1a), L A and L B Each of the above groups is independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonate bond, a sulfonamide bond, a carbonate bond, or a carbamate bond. Among these, a single bond, an ether bond, or an ester bond is preferred.

[0133] In formula (1a), X L A single bond or a C1-40 alkylene group which may contain a heteroatom. The alkylene group may be linear, branched, or cyclic. Specific examples include alkanediyl, cyclic saturated alkylene, and arylene groups. Specific examples of the heteroatom include oxygen, nitrogen, and sulfur atoms.

[0134] X L Specific examples of the alkylene group having 1 to 40 carbon atoms which may contain heteroatoms are shown below, but are not limited thereto. A and L B atomic bonds.

[0135] [Chemistry 13]

[0136]

[0137] [Chemistry 14]

[0138]

[0139] [Chemistry 15]

[0140]

[0141] [Chemistry 16]

[0142]

[0143] Among them, X L -0~X L -22 and X L -47~X L -58.

[0144] The onium salt represented by the formula (1) is preferably represented by the following formula (1A).

[0145] [Chemistry 17]

[0146]

[0147] Where R 1 ~R 13 、R 15 、L A 、X L 、R F , m1~m3 and Z + Same as above.

[0148] The onium salt represented by formula (1A) is preferably represented by the following formula (1B).

[0149] [Chemistry 18]

[0150]

[0151] Where R 5 、R 10 ~R 13 、R 15 、L A 、X L 、R F , m1~m3 and Z + Same as above.

[0152] In formula (1B), m4 and m5 are each independently an integer of 0 to 4. However, in view of the availability of raw materials, both are preferably 0 to 2.

[0153] In formula (1B), R 16 and R 17 Each independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. Specific examples of the halogen atom and the hydrocarbon group can be listed as R 1 ~R 14 The same examples apply to the halogen atoms and hydrocarbon groups represented by .

[0154] When m4 is 2 or more, multiple R 16 They can also be bonded to each other and form a ring together with the carbon atoms to which they are bonded and the carbon atoms between them. When m5 is 2 or more, multiple R 17 They can also be bonded to each other and form a ring together with the carbon atoms to which they are bonded and the carbon atoms between them. Specific examples of the ring formed in this case can be listed and exemplified as R 1 ~R 14 The same example is given for a ring that can be formed by at least two of the above being bonded to each other.

[0155] The onium salt represented by the formula (1B) is preferably represented by the following formula (1C).

[0156] [Chemistry 19]

[0157]

[0158] Where R 5 、R 10 ~R 13 、R 16 、R 17 、L A 、X L , m4, m5 and Z + Same as above.

[0159] Specific examples of the anion of the onium salt represented by formula (1) include the following, but are not limited thereto: In the following formula, Me is a methyl group.

[0160] [Chemistry 20]

[0161]

[0162] [Chemistry 21]

[0163]

[0164] [Chemistry 22]

[0165]

[0166] [Chemistry 23]

[0167]

[0168] [Chemistry 24]

[0169]

[0170] [Chemistry 25]

[0171]

[0172] [Chemistry 26]

[0173]

[0174] [Chemistry 27]

[0175]

[0176] [Chemistry 28]

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[0215]

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[0221]

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[0223]

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[0231]

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[0240] [Chemistry 60]

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[0243]

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[0245]

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[0247]

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[0250] [Chemistry 65]

[0251]

[0252] [Chemistry 66]

[0253]

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[0255]

[0256] [Chemistry 68]

[0257]

[0258] [Chemistry 69]

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[0261]

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[0263]

[0264] [Chemistry 72]

[0265]

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[0267]

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[0269]

[0270] [Chemistry 75]

[0271]

[0272] [Chemistry 76]

[0273]

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[0275]

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[0277]

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[0279]

[0280] [Chemistry 80]

[0281]

[0282] [Chemistry 81]

[0283]

[0284] [Chemistry 82]

[0285]

[0286] [Chemistry 83]

[0287]

[0288] [Chemistry 84]

[0289]

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[0291]

[0292] [Chemistry 86]

[0293]

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[0295]

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[0297]

[0298] [Chemistry 89]

[0299]

[0300] [Chemistry 90]

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[0305]

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[0309]

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[0311]

[0312] [Chemistry 96]

[0313]

[0314] [Chemistry 97]

[0315]

[0316] [Chemistry 98]

[0317]

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[0319]

[0320] [Chemistry 100]

[0321]

[0322] [Chemistry 101]

[0323]

[0324] [Chemistry 102]

[0325]

[0326] [Chemistry 103]

[0327]

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[0329]

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[0331]

[0332] [Chemistry 106]

[0333]

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[0335]

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[0337]

[0338] [Chemistry 109]

[0339]

[0340] [Chemistry 110]

[0341]

[0342] [Chemistry 111]

[0343]

[0344] [Chemistry 112]

[0345]

[0346] [Chemistry 113]

[0347]

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[0349]

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[0373]

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[0377]

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[0379]

[0380] [Chemistry 130]

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[0391]

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[0393]

[0394] [Chemistry 137]

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[0397]

[0398] [Chemistry 139]

[0399]

[0400] [Chemistry 140]

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[0402] [Chemistry 141]

[0403]

[0404] [Chemistry 142]

[0405]

[0406] [Chemistry 143]

[0407]

[0408] [Chemistry 144]

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[0475]

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[0501]

[0502] [Chemistry 191]

[0503]

[0504] [Chemistry 192]

[0505]

[0506] [Chemistry 193]

[0507]

[0508] [Chemistry 194]

[0509]

[0510] [Chemistry 195]

[0511]

[0512] [Chemistry 196]

[0513]

[0514] [Chemistry 197]

[0515]

[0516] [Chemistry 198]

[0517]

[0518] [Chemistry 199]

[0519]

[0520] [Chemistry 200]

[0521]

[0522] In formula (1), Z + The onium cation is preferably a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2).

[0523] [Chemistry 201]

[0524]

[0525] In formula (cation-1) and (cation-2), R ct1 ~R ct5 Each independently represents a halogen atom or a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom.

[0526] R ct1 ~R ct5 Examples of the halogen atom represented by include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0527] R ct1 ~R ct5The hydrocarbon group represented by may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples include: alkyl groups having 1 to 30 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; cyclic saturated hydrocarbon 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; cyclic unsaturated hydrocarbon 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 combinations thereof, preferably aryl groups. Furthermore, part or all of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and part of the -CH2- of the hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, the hydrocarbon group may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like.

[0528] Again, R ct1 and R ct2 They may also be bonded to each other and form a ring together with the sulfur atom to which they are bonded. In this case, the structure of the ring may be represented by the following formula.

[0529] [Chemistry 202]

[0530]

[0531] Where, the dotted line is and R ct3 atomic bonds.

[0532] Specific examples of the sulfonium cation represented by formula (cation-1) include the following, but are not limited thereto.

[0533] [Chemistry 203]

[0534]

[0535] [Chemistry 204]

[0536]

[0537] [Chemistry 205]

[0538]

[0539] [Chemistry 206]

[0540]

[0541] [Chemistry 207]

[0542]

[0543] [Chemistry 208]

[0544]

[0545] [Chemistry 209]

[0546]

[0547] [Chemistry 210]

[0548]

[0549] [Chemistry 211]

[0550]

[0551] [Chemistry 212]

[0552]

[0553] [Chemistry 213]

[0554]

[0555] [Chemistry 214]

[0556]

[0557] [Chemistry 215]

[0558]

[0559] [Chemistry 216]

[0560]

[0561] [Chemistry 217]

[0562]

[0563] [Chemistry 218]

[0564]

[0565] [Chemistry 219]

[0566]

[0567] [Chemistry 220]

[0568]

[0569] [Chemistry 221]

[0570]

[0571] [Chemistry 222]

[0572]

[0573] [Chemistry 223]

[0574]

[0575] [Chemistry 224]

[0576]

[0577] [Chemistry 225]

[0578]

[0579] [Chemistry 226]

[0580]

[0581] [Chemistry 227]

[0582]

[0583] [Chemistry 228]

[0584]

[0585] [Chemistry 229]

[0586]

[0587] Specific examples of the iodonium cation represented by formula (cation-2) include the following, but are not limited thereto.

[0588] [Chemistry 230]

[0589]

[0590] [Chemistry 231]

[0591]

[0592] Specific examples of the onium salt of the present invention include arbitrary combinations of the aforementioned anions and cations.

[0593] The onium salt of the present invention can be synthesized by a known method. As an example, a method for producing an onium salt represented by the following formula (PAG-1-ex) will be described, but the synthesis method is not limited thereto.

[0594] [Chemistry 232]

[0595]

[0596] Where R 1 ~R 13 、R F 、R 15 、L A 、X L , m1~m3 and Z + Same as above. + For the cation. X - For the anion.

[0597] The first step is a step of obtaining the intermediate In-1 by reacting the raw material SM-1 obtained by a commercial product or a known synthesis method with the raw material SM-2. When the carboxyl group of the raw material SM-1 and the hydroxyl group of the raw material SM-2 directly form an ester bond, various condensing agents can be used. Examples of the condensing agents used include: N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, etc. Considering the ease of removing the urea compound generated as a by-product after the reaction, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is preferably used. The reaction is carried out by dissolving the raw materials SM-1 and SM-2 in a halogen-based solvent such as dichloromethane and adding a condensing agent. Adding 4-dimethylaminopyridine (DMAP) as a catalyst can improve the reaction rate. The reaction time is typically about 12 to 24 hours, ideal for yield, if monitored by silica gel thin-layer chromatography (TLC) and completed. After the reaction is terminated, the by-product urea compound is removed by filtration or washing, as needed. The reaction mixture is then subjected to a standard aqueous workup to obtain the intermediate In-1. If necessary, the resulting intermediate In-1 can be purified using conventional methods such as chromatography and recrystallization.

[0598] The second step is to make the intermediate In-1 and Z + X - The step of performing salt exchange on the onium salt (raw material SM-3) represented by X to obtain an onium salt (PAG-1-ex). - Chloride, bromide, iodide, or methylsulfate anion is preferred for ease of quantitative exchange reaction. Confirming the progress of the reaction by TLC is ideal for high yield. The onium salt (PAG-1-ex) can be obtained from the reaction mixture by conventional aqueous workup. If necessary, purification can be performed using conventional methods such as chromatography and recrystallization.

[0599] In the above process, the ion exchange in the second step can be easily performed using a known method, for example, refer to Japanese Patent Application Laid-Open No. 2007-145797.

[0600] The above-mentioned production method is merely an example, and the production method of the onium salt of the present invention is not limited thereto.

[0601] The structural features of the onium salt of the present invention can be listed in that the anion has a condensed ring structure and an aromatic sulfonic acid structure with a substituent. The condensed ring structure with a substituent has a large exclusion volume, acts as a bulky substituent, and highly suppresses the diffusion of the generated acid. In addition, due to its resistance to alkaline developer, the film loss of the pattern of the unexposed portion is reduced. On the other hand, the structure of the acid generated by the aromatic sulfonic acid structure is rigid, which can show the effect of suppressing the diffusion of the acid. The aromatic ring forming the aromatic sulfonic acid structure preferably has a fluorine atom or a sulfonate bond with electron withdrawal as a connecting group, thereby increasing the acidity of the generated acid and efficiently deprotecting the acid-labile group of the base polymer. In addition, although the fluorine atom is not as good as the iodine atom, it is still an element with a high absorption effect of EUV light. Therefore, by increasing the number of fluorine atoms, the amount of secondary electrons generated will be increased, and the decomposition of cations will be promoted, which will contribute to high sensitivity. Japanese Patent No. 7109178 proposes an alkanesulfonic acid-type photoacid generator containing 2 to 4 fluorine atoms. However, due to the alkanesulfonic acid, the acid diffusion is large and the solvent solubility is poor, which raises concerns about development defects. Due to these synergistic effects, the resist composition containing the onium salt of the present invention has high sensitivity and low acid diffusivity. This results in excellent LWR of line patterns and CDU of hole patterns, and allows the formation of patterns with strong pattern collapse resistance, making it ideal for forming fine patterns.

[0602] The aforementioned onium salts can be preferably used as photoacid generators.

[0603] [Chemically amplified resist composition]

[0604] [(A) Photoacid generator]

[0605] The chemically amplified resist composition of the present invention contains (A) a photoacid generator composed of an onium salt represented by formula (1) as an essential component.

[0606] In the chemically amplified resist composition of the present invention, the content of the photoacid generator (A) comprising an onium salt represented by formula (1) is preferably 0.1 to 40 parts by mass, and more preferably 0.5 to 30 parts by mass, relative to 80 parts by mass of the base polymer described below. The content of component (A) within the aforementioned range is preferred because it provides excellent sensitivity and resolution, and eliminates the risk of foreign matter generation after development or during stripping of the resist film. The photoacid generator (A) may be used alone or in combination of two or more.

[0607] [(B) Base polymer]

[0608] The chemically amplified resist composition of the present invention may contain a base polymer as component (B). The base polymer (B) contains a repeating unit represented by the following formula (a1) (hereinafter also referred to as repeating unit a1).

[0609] [Chemistry 233]

[0610]

[0611] In formula (a1), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0612] In formula (a1), X 1 is a single bond, phenylene, naphthylene or *-C(=O)-OX 11 -, and the phenylene group or naphthylene group may be substituted with an alkoxy group having 1 to 10 carbon atoms or a halogen atom which may contain a fluorine atom. 11 It is a saturated alkylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group. The saturated alkylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. * represents an atomic bond to a carbon atom in the main chain.

[0613] In formula (a1), AL 1 The acid-labile group is an acid-labile group. Examples of the acid-labile group include those described in JP-A-2013-80033 and JP-A-2013-83821.

[0614] Representative examples of the acid-labile group include those represented by the following formulae (AL-1) to (AL-3).

[0615] [Chemistry 234]

[0616]

[0617] In the formula, the dotted lines are atomic bonds.

[0618] In formula (AL-1) and (AL-2), R L1 and R L2Each of the above hydrocarbon groups is independently a hydrocarbon group having 1 to 40 carbon atoms and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbon group may be saturated or unsaturated and may be linear, branched, or cyclic. The hydrocarbon group preferably has 1 to 20 carbon atoms.

[0619] In formula (AL-1), k is an integer of 0-10, preferably an integer of 1-5.

[0620] In formula (AL-2), R L3 and R L4 Each of them is independently a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and may also contain heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and fluorine atoms. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. L2 、R L3 and R L4 Any two of them may be bonded to each other and together with the carbon atom to which they are bonded or with the carbon atom and oxygen atom form a ring having 3 to 20 carbon atoms. The aforementioned ring is preferably a ring having 4 to 16 carbon atoms, and is particularly preferably an alicyclic ring.

[0621] In formula (AL-3), R L5 、R L6 and R L7 Each is independently a hydrocarbon group having 1 to 20 carbon atoms, and may contain heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and fluorine atoms. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. L5 、R L6 and R L7 Any two of them may be bonded to each other and together with the carbon atoms to which they are bonded form a ring having 3 to 20 carbon atoms. The aforementioned ring is preferably a ring having 4 to 16 carbon atoms, and is particularly preferably an alicyclic ring.

[0622] Specific examples of the repeating unit a1 include the following, but are not limited thereto. A and AL 1 Same as above.

[0623] [Chemistry 235]

[0624]

[0625] [Chemistry 236]

[0626]

[0627] [Chemistry 237]

[0628]

[0629] The base polymer may further contain a repeating unit represented by the following formula (a2) (hereinafter also referred to as repeating unit a2).

[0630] [Chemistry 238]

[0631]

[0632] In formula (a2), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 2 It is a single bond or *-C(=O)-O-. * represents an atomic bond with a carbon atom of the main chain. 21 AL is a halogen atom, a cyano group, a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom, a hydrocarbon oxy group having 1 to 20 carbon atoms which may contain a hetero atom, a hydrocarbon carbonyl group having 2 to 20 carbon atoms which may contain a hetero atom, a hydrocarbon carbonyloxy group having 2 to 20 carbon atoms which may contain a hetero atom, or a hydrocarbon oxycarbonyl group having 2 to 20 carbon atoms which may contain a hetero atom. 2 The acid-labile group can be exemplified by AL 1 The same examples are given for the acid-labile groups represented by a. a is an integer from 0 to 4, preferably 0 or 1.

[0633] Specific examples of repeating unit a2 include those shown below, but are not limited thereto. A and AL 2 Same as above.

[0634] [Chemistry 239]

[0635]

[0636] [Chemistry 240]

[0637]

[0638] The base polymer preferably further contains 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).

[0639] [Chemistry 241]

[0640]

[0641] In formulas (b1) and (b2), R A are independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 It is a single bond or *-C(=O)-O-. * represents an atomic bond with a carbon atom of the main chain. 31R is a group having 1 to 20 carbon atoms, or a structure containing at least one selected from the group consisting of a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-). 32 is a halogen atom, a hydroxyl group, a nitro group, a hydrocarbon group having 1 to 20 carbon atoms which may contain heteroatoms, a hydrocarbonoxy group having 1 to 20 carbon atoms which may contain heteroatoms, a hydrocarboncarbonyl group having 2 to 20 carbon atoms which may contain heteroatoms, a hydrocarboncarbonyloxy group having 2 to 20 carbon atoms which may contain heteroatoms, or a hydrocarbonoxycarbonyl group having 2 to 20 carbon atoms which may contain heteroatoms. b is an integer from 1 to 4. c is an integer from 0 to 4. However, 1 ≤ b + c ≤ 5.

[0642] Specific examples of the repeating unit b1 include the following, but are not limited thereto. A Same as above.

[0643] [Chemistry 242]

[0644]

[0645] [Chemistry 243]

[0646]

[0647] [Chemistry 244]

[0648]

[0649] [Chemistry 245]

[0650]

[0651] [Chemistry 246]

[0652]

[0653] [Chemistry 247]

[0654]

[0655] [Chemistry 248]

[0656]

[0657] [Chemistry 249]

[0658]

[0659] [Chemistry 250]

[0660]

[0661] [Chemistry 251]

[0662]

[0663] [Chemistry 252]

[0664]

[0665] [Chemistry 253]

[0666]

[0667] [Chemistry 254]

[0668]

[0669] [Chemistry 255]

[0670]

[0671] [Chemistry 256]

[0672]

[0673] [Chemistry 257]

[0674]

[0675] Specific examples of the repeating unit b2 include those shown below, but are not limited thereto. A Same as above.

[0676] [Chemistry 258]

[0677]

[0678] [Chemistry 259]

[0679]

[0680] [Chemistry 260]

[0681]

[0682] [Chemistry 261]

[0683]

[0684] [Chemistry 262]

[0685]

[0686] The repeating unit b1 or b2 preferably has a lactone ring as a polar group in ArF lithography, and preferably has a phenol moiety in KrF lithography, EB lithography, and EUV lithography.

[0687] The aforementioned base polymer may further contain at least one type selected from the repeating unit represented by the following formula (c1) (hereinafter also referred to as repeating unit c1), the repeating unit represented by the following formula (c2) (hereinafter also referred to as repeating unit c2), the repeating unit represented by the following formula (c3) (hereinafter also referred to as repeating unit c3) and the repeating unit represented by the following formula (c4) (hereinafter also referred to as repeating unit c4).

[0688] [Chemistry 263]

[0689]

[0690] In formulas (c1) to (c4), R A are independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 is a single bond or a phenylene group. 2 *-C(=O)-OZ 21 -, *-C(=O)-NH-Z 21 -or*-OZ 21 -.Z 21 It is an aliphatic alkylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining them, and may also contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 3 are independently a single bond, a phenylene group, a naphthylene group or *-C(=O)-OZ 31 -.Z 31 Z is an aliphatic alkylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the aliphatic alkylene group may contain a hydroxyl group, an ether bond, an ester bond or a lactone ring. 4 are independently a single bond, **-Z 41 -C(=O)-O-, **-C(=O)-NH-Z 41 -or**-OZ 41 -.Z 41 It is a C1-20 alkylene group which may contain a heteroatom. 5 are independently a single bond, *-Z 51 -C(=O)-O-, *-C(=O)-NH-Z 51 -or*-OZ 51 -.Z 51 It is a C1-20 alkylene group which may contain a heteroatom. 6 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, phenylene substituted with trifluoromethyl, *-C(=O)-OZ 61 -, *-C(=O)-N(H)-Z 61 -or*-OZ 61 -.Z 61It is an aliphatic alkylene group, phenylene group, fluorinated phenylene group or phenylene group substituted with a trifluoromethyl group having 1 to 6 carbon atoms, and may also contain a carbonyl group, an ester bond, an ether bond or a hydroxyl group. * indicates an atomic bond with a carbon atom of the main chain. ** indicates an atomic bond with Z 3 atomic bonds.

[0691] Z 21 、Z 31 and Z 61 The aliphatic alkylene group represented may be any of linear, branched, and cyclic, and specific examples thereof include: alkanediyl groups such as methane-1,1-diyl, ethane-1,2-diyl, propane-1,1-diyl, propane-1,2-diyl, propane-1,3-diyl, propane-2,2-diyl, butane-1,1-diyl, butane-1,2-diyl, butane-1,3-diyl, butane-2,3-diyl, butane-1,4-diyl, 1,1-dimethylethane-1,2-diyl, pentane-1,5-diyl, 2-methylbutane-1,2-diyl, and hexane-1,6-diyl; cycloalkanediyl groups such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; and groups obtained by combining these groups.

[0692] Z 41 and Z 51 The alkylene group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the following, but are not limited thereto.

[0693] [Chemistry 264]

[0694]

[0695] In the formula, the dotted lines are atomic bonds.

[0696] In formula (c1), R 41 and R 42Each independently represents a hydrocarbon group having 1 to 20 carbon atoms, which may also contain heteroatoms. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include: alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; cyclic saturated hydrocarbon groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated hydrocarbon groups having 3 to 20 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, naphthyl, and thienyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and combinations thereof, preferably aryl groups. Furthermore, part or all of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and part of the -CH2- of the hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, the hydrocarbon group may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like.

[0697] Again, R 41 and R 42 They may also be bonded to each other and form a ring together with the sulfur atom to which they are bonded. In this case, the ring may be exemplified as R in the description of formula (cation-1). ct1 and R ct2 The same example is true of the rings that can be formed when the two atoms are bonded together and when they are bonded to the sulfur atoms.

[0698] Specific examples of the cation of the repeating unit c1 include the following, but are not limited thereto. A Same as above.

[0699] [Chemistry 265]

[0700]

[0701] [Chemistry 266]

[0702]

[0703] [Chemistry 267]

[0704]

[0705] [Chemistry 268]

[0706]

[0707] [Chemistry 269]

[0708]

[0709] [Chemistry 270]

[0710]

[0711] [Chemistry 271]

[0712]

[0713] In formula (c1), M - It is a non-nucleophilic counter ion. The aforementioned non-nucleophilic counter ion is preferably a halide ion, a sulfonic acid anion, an imidic acid anion, and a methylated acid anion. Specific examples of the aforementioned halide ion include chloride ion, bromide ion, and the like. Specific examples of the aforementioned sulfonic acid anion (sulfonate ion) include fluoroalkylsulfonate ions such as trifluoromethanesulfonate ion, 1,1,1-trifluoroethanesulfonate ion, and nonafluorobutanesulfonate ion; arylsulfonate ions such as toluenesulfonate ion, benzenesulfonate ion, 4-fluorobenzenesulfonate ion, and 1,2,3,4,5-pentafluorobenzenesulfonate ion; methanesulfonate ion, butanesulfonate ion, and alkylsulfonate ions. Specific examples of the aforementioned imidic acid anions (imide ions) include bis(trifluoromethylsulfonyl)imide ions, bis(perfluoroethylsulfonyl)imide ions, and bis(perfluorobutylsulfonyl)imide ions. Specific examples of the aforementioned methylated acid anions (methide ions) include tris(trifluoromethylsulfonyl)methide ions and tris(perfluoroethylsulfonyl)methide ions.

[0714] Other examples of the non-nucleophilic counter ion include anions represented by any one of the following formulae (c1-1) to (c1-4).

[0715] [Chemistry 272]

[0716]

[0717] In formula (c1-1), R fa is a fluorine atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbon group may be saturated or unsaturated and may be linear, branched or cyclic. Specific examples thereof include those shown as R in the formula (c1-1-1) described below. fa1 The same examples apply to the hydrocarbon groups represented by .

[0718] The anion represented by the formula (c1-1) is preferably represented by the following formula (c1-1-1).

[0719] [Chemistry 273]

[0720]

[0721] In formula (c1-1-1), Q 11 and Q 12 Each of them is independently a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms. In order to improve solvent solubility, at least one of them is preferably a trifluoromethyl group. m is an integer of 0 to 4, and is particularly preferably 1. fa1 It is a hydrocarbon group having 1 to 35 carbon atoms, which may contain a heteroatom. The heteroatom is preferably an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or the like, with an oxygen atom being more preferred. The hydrocarbon group is particularly preferably one having 6 to 30 carbon atoms, in view of achieving high resolution in fine pattern formation.

[0722] In formula (c1-1-1), R fa1 The hydrocarbon group having 1 to 35 carbon atoms represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include: alkyl groups having 1 to 35 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, 2-ethylhexyl, nonyl, undecyl, tridecyl, pentadecyl, heptadecyl, and eicosyl; cyclic saturated hydrocarbon groups having 3 to 35 carbon atoms, such as cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, 1-adamantylmethyl, norbornyl, norbornylmethyl, tricyclodecanyl, tetracyclododecyl, tetracyclododecylmethyl, and dicyclohexylmethyl; unsaturated aliphatic hydrocarbon groups having 2 to 35 carbon atoms, such as allyl and 3-cyclohexenyl; aryl groups having 6 to 35 carbon atoms, such as phenyl, 1-naphthyl, 2-naphthyl, and 9-fluorenyl; aralkyl groups having 7 to 35 carbon atoms, such as benzyl and diphenylmethyl; and groups obtained by combining these.

[0723] Furthermore, some or all of the hydrogen atoms of the aforementioned hydrocarbon 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 of the hydrocarbon groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, or nitrogen atoms. Consequently, the hydrocarbon groups may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, nitro groups, carbonyl groups, ether bonds, ester bonds, sulfonate bonds, carbonate bonds, lactone rings, sultone rings, carboxylic anhydride (-C(=O)-OC(=O)-), haloalkyl groups, and the like. Examples of the hydrocarbon groups containing heteroatoms include tetrahydrofuranyl, methoxymethyl, ethoxymethyl, methylthiomethyl, acetamidomethyl, trifluoroethyl, (2-methoxyethoxy)methyl, acetoxymethyl, 2-carboxy-1-cyclohexyl, 2-oxopropyl, 4-oxo-1-adamantyl, and 3-oxocyclohexyl.

[0724] In formula (c1-1-1), L a1It is a single bond, an ether bond, an ester bond, a sulfonate bond, a carbonate bond or a carbamate bond. From the viewpoint of synthesis, it is preferably an ether bond or an ester bond, and more preferably an ester bond.

[0725] Specific examples of anions represented by formula (c1-1) include the following, but are not limited thereto. 11 As mentioned above, Ac is acetyl.

[0726] [Chemistry 274]

[0727]

[0728] [Chemistry 275]

[0729]

[0730] [Chemistry 276]

[0731]

[0732] [Chemistry 277]

[0733]

[0734] [Chemistry 278]

[0735]

[0736] [Chemistry 279]

[0737]

[0738] [Chemistry 280]

[0739]

[0740] [Chemistry 281]

[0741]

[0742] [Chemistry 282]

[0743]

[0744] [Chemistry 283]

[0745]

[0746] In formula (c1-2), R fb1 and R fb2Each of them is independently a fluorine atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbon group may be saturated or unsaturated and may be linear, branched or cyclic. Specific examples thereof include: fa1 The same examples are given for the hydrocarbon groups represented by R fb1 and R fb2 It is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 They can also bond to each other and to the groups to which they are bonded (-CF2-SO2-N - -SO2-CF2-) together to form a ring, at this time, R fb1 and R fb2 The groups formed by mutual bonding are preferably fluorinated ethylene groups or fluorinated propylene groups.

[0747] In formula (c1-3), R fc1 、R fc2 and R fc3 Each of them is independently a fluorine atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbon group may be saturated or unsaturated and may be linear, branched or cyclic. Specific examples thereof include: fa1 The same examples are given for the hydrocarbon groups represented by R fc1 、R fc2 and R fc3 It is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 They can also bond to each other and to the groups to which they are bonded (-CF2-SO2-C - -SO2-CF2-) together to form a ring, at this time, R fc1 and R fc2 The groups formed by mutual bonding are preferably fluorinated ethylene groups or fluorinated propylene groups.

[0748] In formula (c1-4), R fd is a hydrocarbon group having 1 to 40 carbon atoms which may contain heteroatoms. The hydrocarbon group may be saturated or unsaturated and may be linear, branched or cyclic. Specific examples thereof include: fa1 The same examples are given for the hydrocarbon groups represented.

[0749] Specific examples of the anion represented by formula (c1-4) include the following, but are not limited thereto.

[0750] [Chemistry 284]

[0751]

[0752] [Chemistry 285]

[0753]

[0754] Examples of the non-nucleophilic counter ion include anions having an aromatic ring substituted with an iodine atom or a bromine atom. Specific examples of such anions include those represented by the following formula (c1-5).

[0755] [Chemistry 286]

[0756]

[0757] In formula (c1-5), x is an integer satisfying 1≤x≤3. y and z are integers satisfying 1≤y≤5, 0≤z≤3, and 1≤y+z≤5. Y is preferably an integer satisfying 1≤y≤3, more preferably 2 or 3. Z is preferably an integer satisfying 0≤z≤2.

[0758] In formula (c1-5), X BI is an iodine atom or a bromine atom. When x and / or y are 2 or more, they may be the same as or different from each other.

[0759] In formula (c1-5), L 11 It is a saturated alkylene group having 1 to 6 carbon atoms and may contain a single bond, an ether bond, an ester bond, or an ether bond or an ester bond. The saturated alkylene group may be linear, branched, or cyclic.

[0760] In formula (c1-5), L 12 When x is 1, it is a single bond or a divalent linking group having 1 to 20 carbon atoms. When x is 2 or 3, it is a (x+1)-valent linking group having 1 to 20 carbon atoms. The linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0761] In formula (c1-5), R fe is a hydroxyl group, a carboxyl group, a fluorine atom, a chlorine atom, a bromine atom, or an amino group, or a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbonoxy group having 1 to 20 carbon atoms, a hydrocarboncarbonyl group having 2 to 20 carbon atoms, a hydrocarbonoxycarbonyl group having 2 to 20 carbon atoms, a hydrocarboncarbonyloxy group having 2 to 20 carbon atoms, or a hydrocarbonsulfonyloxy group having 1 to 20 carbon atoms, which may contain a fluorine atom, a chlorine atom, a bromine atom, a hydroxyl group, an amino group, or an ether bond, or -N(R feA )(R feB ), -N(R feC )-C(=O)-R feD or -N(R feC )-C(=O)-OR feD . R feA and R feB R is independently a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms. feCR is a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms, and may contain a halogen atom, a hydroxyl group, a saturated hydrocarbon oxy group having 1 to 6 carbon atoms, a saturated hydrocarbon carbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbon carbonyloxy group having 2 to 6 carbon atoms. feD It is an aliphatic hydrocarbon group having 1 to 16 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may also contain a halogen atom, a hydroxyl group, a saturated hydrocarbon oxy group having 1 to 6 carbon atoms, a saturated hydrocarbon carbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbon carbonyloxy group having 2 to 6 carbon atoms. The aforementioned aliphatic hydrocarbon group may be saturated or unsaturated, and may be straight-chain, branched, or cyclic. The aforementioned hydrocarbon group, hydrocarbon oxy group, hydrocarbon carbonyl group, hydrocarbon oxycarbonyl group, hydrocarbon carbonyloxy group, and hydrocarbon sulfonyloxy group may be straight-chain, branched, or cyclic. When x and / or z are 2 or more, each R fe They can be the same or different.

[0762] Among them, R fe Preferably, it is hydroxyl, -N(R feC )-C(=O)-R feD 、-N(R feC )-C(=O)-OR feD , fluorine atom, chlorine atom, bromine atom, methyl group, methoxy group, etc.

[0763] In formula (c1-5), Rf 11 ~Rf 14 are independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, but at least one of them is a fluorine atom or a trifluoromethyl group. 11 With Rf 12 They can also combine to form carbonyl groups. 13 and Rf 14 Fluorine atoms are particularly preferred.

[0764] Specific examples of anions represented by formula (c1-5) include the following, but are not limited thereto. BI Same as above.

[0765] [Chemistry 287]

[0766]

[0767] [Chemistry 288]

[0768]

[0769] [Chemistry 289]

[0770]

[0771] [Chemistry 290]

[0772]

[0773] [Chemistry 291]

[0774]

[0775] [Chemistry 292]

[0776]

[0777] [Chemistry 293]

[0778]

[0779] [Chemistry 294]

[0780]

[0781] [Chemistry 295]

[0782]

[0783] [Chemistry 296]

[0784]

[0785] [Chemistry 297]

[0786]

[0787] [Chemistry 298]

[0788]

[0789] [Chemistry 299]

[0790]

[0791] [Chemistry 300]

[0792]

[0793] [Chemistry 301]

[0794]

[0795] [Chemistry 302]

[0796]

[0797] [Chemistry 303]

[0798]

[0799] [Chemistry 304]

[0800]

[0801] [Chemistry 305]

[0802]

[0803] [Chemistry 306]

[0804]

[0805] [Chemistry 307]

[0806]

[0807] [Chemistry 308]

[0808]

[0809] [Chemistry 309]

[0810]

[0811] The aforementioned non-nucleophilic counter ions may also be used: fluorobenzenesulfonic acid anions bonded to an aromatic group containing an iodine atom as described in Japanese Patent No. 6648726, anions having an acid-decomposition mechanism as described in International Publication No. 2021 / 200056 and Japanese Patent Application Laid-Open No. 2021-70692, anions having a cyclic ether group as described in Japanese Patent Application Laid-Open No. 2018-180525 and Japanese Patent Application Laid-Open No. 2021-35935, and anions as described in Japanese Patent Application Laid-Open No. 2018-92159.

[0812] The aforementioned non-nucleophilic counterions may further include: anions of bulky benzenesulfonic acid derivatives containing no fluorine atoms as described in Japanese Patent Application Laid-Open Nos. 2006-276759, 2015-117200, 2016-65016, and 2019-202974; and benzenesulfonic acid anions containing no fluorine atoms and bonded to an aromatic group containing an iodine atom as described in Japanese Patent No. 6645464; and alkylsulfonic acid anions.

[0813] The aforementioned non-nucleophilic counter ions may also be used: anions of disulfonic acids described in JP-A-2015-206932, anions of sulfonic acids on one side and different sulfonamides or sulfonimides on the other side as described in WO-2020 / 158366, and anions of sulfonic acids on one side and carboxylic acids on the other side as described in JP-A-2015-24989.

[0814] In formulas (c2) and (c3), L 1It is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond or a carbamate bond. Among them, from the viewpoint of synthesis, an ether bond, an ester bond or a carbonyl group is preferred, and an ester bond or a carbonyl group is more preferred.

[0815] In formula (c2), Rf 1 and Rf 2 Each independently represents a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms. 1 and Rf 2 In order to increase the acid strength of the generated acid, it is preferable that all of them are fluorine atoms. 3 and Rf 4 Each of them is independently a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms. 3 and Rf 4 At least one of them is preferably a trifluoromethyl group.

[0816] In formula (c3), Rf 5 and Rf 6 are independently a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms. 5 and Rf 6 They are not hydrogen atoms at the same time. Among them, in order to improve the solvent solubility, Rf 5 and Rf 6 At least one of them is preferably a trifluoromethyl group.

[0817] In formulae (c2) and (c3), d is an integer of 0 to 3, preferably 1.

[0818] Specific examples of the anion of the repeating unit c2 include the following, but are not limited thereto. A Same as above, Me is methyl.

[0819] [Chemistry 310]

[0820]

[0821] [Chemistry 311]

[0822]

[0823] [Chemistry 312]

[0824]

[0825] [Chemistry 313]

[0826]

[0827] [Chemistry 314]

[0828]

[0829] [Chemistry 315]

[0830]

[0831] [Chemistry 316]

[0832]

[0833] [Chemistry 317]

[0834]

[0835] [Chemistry 318]

[0836]

[0837] Specific examples of the anion of the repeating unit c3 include those shown below, but are not limited thereto. A Same as above.

[0838] [Chemistry 319]

[0839]

[0840] [Chemistry 320]

[0841]

[0842] [Chemistry 321]

[0843]

[0844] [Chemistry 322]

[0845]

[0846] [Chemistry 323]

[0847]

[0848] [Chemistry 324]

[0849]

[0850] [Chemistry 325]

[0851]

[0852] [Chemistry 326]

[0853]

[0854] Specific examples of the anion of the repeating unit c4 include the following, but are not limited thereto. A Same as above.

[0855] [Chemistry 327]

[0856]

[0857] In formulas (c2) to (c4), A + is an onium cation. Examples of the onium cation include ammonium cations, sulfonium cations, and iodonium cations, preferably sulfonium cations and iodonium cations. Specific examples thereof include, but are not limited to, those exemplified as the sulfonium cations represented by formula (cation-1) and the iodonium cations represented by formula (cation-2), or the same examples as those exemplified as the ammonium cations represented by formula (cation-3) described later.

[0858] Specific structures of the repeating units c1 to c4 include any combination of the aforementioned anions and cations.

[0859] Among repeating units c1 to c4, repeating units c2, c3, and c4 are preferred from the perspective of controlling acid diffusion, repeating units c2 and c4 are more preferred from the perspective of the acid strength of the generated acid, and repeating unit c2 is more preferred from the perspective of solvent solubility.

[0860] The base polymer may further contain a repeating unit having a structure in which a hydroxyl group is protected by an acid-labile group (hereinafter also referred to as repeating unit d). Repeating unit d is not particularly limited as long as it has a structure in which one or more hydroxyl groups are protected and the protecting group decomposes upon the action of an acid to generate a hydroxyl group, but is preferably represented by the following formula (d1).

[0861] [Chemistry 328]

[0862]

[0863] In formula (d1), R A Same as above. 41 It is a (e+1)-valent hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom. 42 is an acid-labile group. e is an integer of 1 to 4.

[0864] In formula (d1), R 42 The acid-labile group represented by R may be any one that is deprotected by the action of an acid to generate a hydroxyl group. 42 The structure of is not particularly limited, and is preferably an acetal structure, a ketal structure, an alkoxycarbonyl group, an alkoxymethyl group represented by the following formula (d2), and is particularly preferably an alkoxymethyl group represented by the following formula (d2).

[0865] [Chemical formula 329]

[0866]

[0867] In the formula, * represents an atomic bond. R 43 represents a hydrocarbon group having 1 to 15 carbon atoms.

[0868] R 42 represents an acid-labile group, and specific examples of the alkoxymethyl group represented by formula (d2) and the repeating unit d can be the same as those exemplified in the description of the repeating unit d described in Japanese Patent Application Laid-Open No. 2020-111564.

[0869] The aforementioned base polymer may further contain a repeating unit e derived from indene, benzofuran, benzothiophene, acenaphthene, chromone, coumarin, norbornadiene or their derivatives. Specific examples of the monomer providing the repeating unit e are as shown below, but are not limited thereto.

[0870] [Chemical formula 330]

[0871]

[0872] The aforementioned base polymer may further contain a repeating unit f derived from indane, vinylpyridine or vinylcarbazole.

[0873] In the polymer of the present invention, the content ratios of the repeating units a1, a2, b1, b2, c1 to c4, d, e and f are preferably 0 < a1 ≤ 0.8, 0 ≤ a2 ≤ 0.8, 0 ≤ b1 ≤ 0.6, 0 ≤ b2 ≤ 0.6, 0 ≤ c1 ≤ 0.4, 0 ≤ c2 ≤ 0.4, 0 ≤ c3 ≤ 0.4, 0 ≤ c4 ≤ 0.4, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 0.3 and 0 ≤ f ≤ 0.3, and more preferably 0 < a1 ≤ 0.7, 0 ≤ a2 ≤ 0.7, 0 ≤ b1 ≤ 0.5, 0 ≤ b2 ≤ 0.5, 0 ≤ c1 ≤ 0.3, 0 ≤ c2 ≤ 0.3, 0 ≤ c3 ≤ 0.3, 0 ≤ c4 ≤ 0.3, 0 ≤ d ≤ 0.3, 0 ≤ e ≤ 0.3 and 0 ≤ f ≤ 0.3.

[0874] The weight average molecular weight (Mw) of the aforementioned polymer is preferably 1,000 to 500,000, and more preferably 3,000 to 100,000. If Mw is within this range, sufficient etching resistance can be obtained, and there is no concern about the reduction in resolution caused by the inability to ensure the difference in dissolution rate before and after exposure. In addition, in the present invention, Mw is a polystyrene conversion measurement value obtained by gel permeation chromatography (GPC) using THF or N,N-dimethylformamide (DMF) as a solvent.

[0875] Furthermore, regarding the molecular weight distribution (Mw / Mn) of the aforementioned polymer, since the influence of Mw / Mn tends to increase with the miniaturization of pattern rules, a narrow distribution with Mw / Mn of 1.0 to 2.0 is preferred to obtain a resist composition ideally suited for fine pattern sizes. Within this range, the presence of low- and high-molecular-weight polymers is reduced, and there is no concern of foreign matter being observed on the pattern after exposure or of deterioration in pattern shape.

[0876] To synthesize the aforementioned polymer, for example, a monomer providing the aforementioned repeating unit may be added with a radical polymerization initiator in an organic solvent and heated to carry out polymerization.

[0877] 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). Examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), 1,1'-azobis(1-acetoxy-1-phenylethane), benzoyl peroxide, and lauroyl peroxide. The amount of these initiators added is preferably 0.01 to 25 mol% relative to the total amount of the monomers to be polymerized. The reaction temperature is preferably 50 to 150°C, more preferably 60 to 100°C. The reaction time is preferably 2 to 24 hours, and more preferably 2 to 12 hours from the perspective of production efficiency.

[0878] The polymerization initiator can be added to the monomer solution and supplied to the reactor, or an initiator solution different from the monomer solution can be prepared and supplied to the reactor separately. Since there is a possibility that the polymerization reaction will proceed and form an ultra-high molecular weight polymer due to free radicals generated from the initiator during the standby time, the monomer solution and the initiator solution should be prepared separately and added dropwise from the perspective of quality control. The acid-labile group can be directly introduced into the monomer, or it can be protected or partially protected after polymerization. In addition, in order to adjust the molecular weight, a well-known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol can be used in combination. In this case, the amount of these chain transfer agents added is preferably 0.01 to 20 mol% relative to the total amount of the monomers to be polymerized.

[0879] In the case of monomers containing hydroxyl groups, the hydroxyl groups can be replaced with acetal groups such as ethoxyethoxy groups that are easily deprotected by acid during polymerization, and then deprotected using weak acid and water after polymerization. Alternatively, the hydroxyl groups can be replaced with acetyl groups, formyl groups, pivaloyl groups, etc., and then alkaline hydrolysis can be performed after polymerization.

[0880] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, hydroxystyrene or hydroxyvinylnaphthalene and other monomers can be added with a free radical polymerization initiator in an organic solvent and heated for polymerization. Alternatively, acetoxystyrene or acetoxyvinylnaphthalene can be used, and after polymerization, the acetoxy group can be deprotected by alkaline hydrolysis to obtain polyhydroxystyrene or hydroxyvinylnaphthalene.

[0881] The base used in the alkaline hydrolysis may be ammonia water, 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.

[0882] The amount of each monomer in the monomer solution may be appropriately set, for example, so as to achieve an ideal content ratio of the repeating unit.

[0883] The polymer obtained by the above-mentioned production method can be a reaction solution obtained by the polymerization reaction as the final product, or a powder obtained by a purification step such as a reprecipitation method in which the polymerization solution is added to a poor solvent to obtain a powder can be used as the final product. From the perspective of operating efficiency and quality stabilization, it is preferable to use a polymer solution obtained by dissolving the powder obtained by the purification step in a solvent as the final product.

[0884] Specific examples of the solvent used at this time include ketones such as cyclohexanone and methyl-2-n-pentyl ketone described in paragraphs

[0144] to

[0145] of Japanese Patent Application Laid-Open 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, Ethers such as diethylene glycol dimethyl ether; esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; lactones such as GBL; alcohols such as diacetone alcohol (DAA); high-boiling point alcohol solvents such as diethylene glycol, propylene glycol, glycerol, 1,4-butanediol, and 1,3-butanediol; and mixed solvents thereof.

[0885] 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.

[0886] The reaction solution and polymer solution are preferably filtered. Filtering can remove foreign matter and gel that may cause defects, which is effective in stabilizing quality.

[0887] Materials used for the aforementioned filter filtration include fluorocarbons, celluloses, nylons, polyesters, and hydrocarbons. In the step of filtering the resist composition, 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 appropriately selected based on the desired cleanliness, preferably being 100 nm or less, and more preferably 20 nm or less. These filters may be used singly or in combination. The filtration method may involve passing the solution through only once, but it is more preferred to circulate the solution and perform multiple filtrations. The filtration step can be performed in any order and at any number of times during the polymer production step. It is preferred to filter the reaction solution, the polymer solution, or both after the polymerization reaction.

[0888] The base polymer (B) may be used alone or in combination of two or more polymers having different composition ratios, Mw and / or Mw / Mn. Furthermore, the base polymer (B) may contain, in addition to the aforementioned polymers, a hydrogenated ring-opening metathesis polymer, for which the polymers described in Japanese Patent Application Laid-Opening No. 2003-66612 may be used.

[0889] [(C) Organic solvent]

[0890] The chemically amplified resist composition of the present invention may also contain an organic solvent as component (C). The organic solvent (C) is not particularly limited as long as it can dissolve the aforementioned components and the components described below. 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, t-butyl acetate, t-butyl propionate, and propylene glycol mono-t-butyl ether acetate; lactones such as GBL; and mixed solvents thereof.

[0891] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, cyclohexanone, GBL, DAA, and mixed solvents thereof are preferred because they have particularly good solubility in the base polymer of the component (B).

[0892] In the chemically amplified resist composition of the present invention, the content of the organic solvent (C) is preferably 200 to 5000 parts by mass, more preferably 400 to 3500 parts by mass, relative to 80 parts by mass of the base polymer (B). The organic solvent (C) may be used alone or as a mixture of two or more.

[0893] [(D) Quencher]

[0894] The chemically amplified resist composition of the present invention may also contain a quencher as component (D). The quencher herein is a material that traps the acid generated by the photoacid generator in the chemically amplified resist composition, preventing it from diffusing into unexposed areas and thereby forming a desired pattern.

[0895] (D) Examples of the quencher include onium salts represented by the following formula (2) or (3).

[0896] [Chemistry 331]

[0897]

[0898] In formula (2), R q1 is a hydrogen atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom, but excludes the case where the hydrogen atom bonded to the carbon atom at the α position of the sulfonic group is substituted by a fluorine atom or a fluoroalkyl group. q2 It is a hydrogen atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a hetero atom.

[0899] R q1 Specific examples of the hydrocarbon group having 1 to 40 carbon atoms 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, tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbon groups having 3 to 40 carbon atoms, such as decyl and adamantyl; aryl groups having 6 to 40 carbon atoms, such as phenyl, naphthyl, and anthracenyl. Furthermore, some or all of the hydrogen atoms of the aforementioned hydrocarbon groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- of the hydrocarbon groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. As a result, the hydrocarbon groups may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonate bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, and the like.

[0900] R q2 Specific examples of the hydrocarbon group represented by R include q1 Specific examples of the substituent include fluorinated saturated hydrocarbon groups such as trifluoromethyl and trifluoroethyl, and fluorinated aryl groups such as pentafluorophenyl and 4-trifluoromethylphenyl.

[0901] Specific examples of the anion of the onium salt represented by formula (2) include the following, but are not limited thereto.

[0902] [Chemistry 332]

[0903]

[0904] [Chemistry 333]

[0905]

[0906] [Chemistry 334]

[0907]

[0908] [Chemistry 335]

[0909]

[0910] Specific examples of the anion of the onium salt represented by formula (3) include the following, but are not limited thereto.

[0911] [Chemistry 336]

[0912]

[0913] [Chemistry 337]

[0914]

[0915] [Chemistry 338]

[0916]

[0917] In formulas (2) and (3), Mq + The onium cation is preferably a sulfonium cation represented by the above formula (cation-1), an iodonium cation represented by the above formula (cation-2), or an ammonium cation represented by the following formula (cation-3).

[0918] [Chemistry 339]

[0919]

[0920] In formula (cation-3), R ct6 ~R ct9 are each independently a hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom. ct6 With R ct7 They may also be bonded to each other and form a ring together with the nitrogen atom to which they are bonded. The aforementioned hydrocarbon group may be exemplified as R in the description of formula (cation-1) and (cation-2). ct1 ~R ct5 The same examples apply to the hydrocarbon groups represented by .

[0921] Specific examples of the ammonium cation represented by formula (cation-3) include the following, but are not limited thereto.

[0922] [Chemistry 340]

[0923]

[0924] Specific examples of the onium salt represented by formula (2) or (3) include any combination of the aforementioned anions and cations. Furthermore, these onium salts can be easily prepared using an ion exchange reaction using a known organic chemical method. For example, the ion exchange reaction can be described in Japanese Patent Application Laid-Open No. 2007-145797.

[0925] The onium salt represented by formula (2) or (3) functions as a quencher in the chemically amplified resist composition of the present invention. This is because each counter anion of the onium salt is a conjugate base of a weak acid. Here, the weak acid means an acid that exhibits an acidity that is not sufficient to deprotect the acid-labile group of the unit containing the acid-labile group used in the base polymer. When the onium salt represented by formula (2) or (3) is used in combination with an onium salt-type photoacid generator having a conjugate base of a strong acid such as a sulfonic acid with fluorination at the α-position as a counter anion, it functions as a quencher. That is, when an onium salt that generates a strong acid such as a sulfonic acid with fluorination at the α-position is mixed with an onium salt that generates a weak acid such as a sulfonic acid or a carboxylic acid that is not fluorinated, the strong acid generated from the photoacid generator upon irradiation with high-energy radiation collides with the onium salt having an unreacted weak acid anion, and the weak acid is released by salt exchange, thereby generating an onium salt having a strong acid anion. In this process, the strong acid is exchanged for a weaker acid with lower catalytic capacity, which in turn causes the acid to be deactivated, thereby allowing for control of acid diffusion.

[0926] Furthermore, as the quencher (D), an onium salt having a sulfonium cation and a phenoxide anion in the same molecule as described in Japanese Patent No. 6848776 may be used, or an onium salt having a sulfonium cation and a carboxylate anion in the same molecule as described in Japanese Patent No. 6583136 and Japanese Patent Application Laid-Open No. 2020-200311, or an onium salt having an iodonium cation and a carboxylate anion in the same molecule as described in Japanese Patent No. 6274755 may be used.

[0927] Here, it is believed that when the photoacid generator that generates a strong acid is an onium salt, the strong acid generated by high-energy radiation can be exchanged for a weak acid as described above. However, it is believed that the weak acid generated by high-energy radiation irradiation and the onium salt that generated the unreacted strong acid collide with each other, making salt exchange difficult. This is because the onium cation easily forms an ion pair with the anion of the stronger acid.

[0928] When the chemically amplified resist composition of the present invention contains an onium salt represented by formula (2) or (3) as the quencher (D), 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 (B). When the onium salt-type quencher (component (D)) is within the aforementioned range, resolution is excellent and sensitivity is not significantly reduced, which is preferable. The onium salt represented by formula (2) or (3) may be used alone or in combination of two or more.

[0929] The chemically amplified resist composition of the present invention may also contain a nitrogen-containing compound as the quencher (D). Examples of the nitrogen-containing compound as component (D) include the primary, secondary, or tertiary amine compounds described in paragraphs

[0146] to

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

[0930] Alternatively, a sulfonium sulfonate salt with a nitrogen-containing substituent can be used as the nitrogen-containing compound. Such a compound acts as a quencher in the unexposed area, but loses its quenching ability in the exposed area due to neutralization with the acid it produces, effectively acting as a photodestructive base. The use of a photodestructive base can further enhance the contrast between the exposed and unexposed areas. Examples of photodestructive bases include Japanese Patent Application Publication Nos. 2009-109595 and 2012-46501.

[0931] When the chemically amplified resist composition of the present invention contains a nitrogen-containing compound as the quencher (D), its content 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 (B). The nitrogen-containing compound may be used alone or in combination of two or more.

[0932] [(E) Other photoacid generators]

[0933] The chemically amplified resist composition of the present invention may contain a photoacid generator other than component (A) (hereinafter referred to as "other photoacid generator") as component (E). The other photoacid generator is not particularly limited as long as it is a compound that generates an acid upon irradiation with high-energy radiation. Preferred other photoacid generators include those represented by the following formula (4) or (5).

[0934] [Chemistry 341]

[0935]

[0936] In formula (4), R 101 ~R 105are each independently a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 101 、R 102 and R 103 Any two of them may be bonded to each other and form a ring together with the sulfur atom to which they are bonded. The aforementioned hydrocarbon group may be exemplified as R in the description of formula (cation-1) and (cation-2). ct1 ~R ct5 The same examples apply to the hydrocarbon groups represented by .

[0937] Specific examples of the cation of the sulfonium salt represented by formula (4) include the same examples as those exemplified for the sulfonium cation represented by formula (cation-1). Specific examples of the cation of the iodonium salt represented by formula (5) include the same examples as those exemplified for the iodonium cation represented by formula (cation-2).

[0938] In formulas (4) and (5), Xa - The anion of a strong acid can be any one of the anions of formula (c1-1) to (c1-5).

[0939] Furthermore, the other photoacid generator of the component (E) is preferably represented by the following formula (6).

[0940] [Chemistry 342]

[0941]

[0942] In formula (6), R 201 and R 202 Each of R is independently a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom. 203 is a C1-30 alkylene group which may contain a hetero atom. 201 、R 202 and R 203 Any two of them may be bonded to each other and form a ring together with the sulfur atom to which they are bonded.

[0943] R 201 and R 202 The hydrocarbon group having 1 to 30 carbon atoms represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include: alkyl groups having 1 to 30 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, oxanorbornyl, tricyclo[5.2.1.0 2,6

[0015] Cyclic saturated hydrocarbon groups having 3 to 30 carbon atoms, such as decyl and adamantyl; aryl groups having 6 to 30 carbon atoms, such as phenyl, tolyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, sec-butylphenyl, tert-butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, sec-butylnaphthyl, tert-butylnaphthyl, and anthracenyl; and groups derived from combinations thereof. Furthermore, some or all of the hydrogen atoms of the aforementioned hydrocarbon groups may be substituted with groups containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms, and some of the -CH2- groups in the hydrocarbon groups may be substituted with groups containing heteroatoms such as oxygen, sulfur, or nitrogen atoms. Consequently, the hydrocarbon groups may contain hydroxyl groups, cyano groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, carbonyl groups, ether bonds, ester bonds, sulfonate bonds, carbonate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), and haloalkyl groups.

[0944] R 203 The alkylene group having 1 to 30 carbon atoms may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include methanediyl, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl, dodecane-1,12-diyl, tridecane-1,13-diyl, tetradecane-1,14-diyl, pentadecane-1,15-diyl, hexadecane-1,16-diyl, and 1,17-diyl. an alkanediyl group having 1 to 30 carbon atoms, such as cyclopentanediyl, cyclohexanediyl, norbornanediyl, and adamantanediyl; an arylene group having 3 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 the like. Furthermore, some or all of the hydrogen atoms of the aforementioned hydrocarbylene group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, or halogen atoms, and some of the -CH2- groups of the aforementioned hydrocarbylene group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, or nitrogen atoms. As a result, the group may contain a hydroxyl group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like. The aforementioned heteroatom is preferably an oxygen atom.

[0945] In formula (6), L Ais a single bond, an ether bond, or a carbon number 1 to 20 alkylene group which may contain heteroatoms. The aforementioned alkylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include and are exemplified as R 203 The same examples are shown for the alkylene groups.

[0946] In formula (6), X a 、X b 、X c and X d are independently a hydrogen atom, a fluorine atom or a trifluoromethyl group. a 、X b 、X c and X d At least one of them is a fluorine atom or a trifluoromethyl group.

[0947] The photoacid generator represented by formula (6) is preferably represented by the following formula (6').

[0948] [Chemistry 343]

[0949]

[0950] In formula (6'), L A Same as above. X e R is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. 301 、R 302 and R 303 Each of them is independently a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbon group may be saturated or unsaturated and may be linear, branched or cyclic. Specific examples thereof include: fa1 The same examples are given for the hydrocarbon groups represented by . p and q are each independently an integer of 0-5, and r is an integer of 0-4.

[0951] Examples of the photo-acid generator represented by formula (6) include the same examples as those given as examples of the photo-acid generator represented by formula (2) in JP-A-2017-26980.

[0952] Among the other photoacid generators mentioned above, those containing anions represented by formula (c1-1-1) or (c1-4) are particularly preferred because they have low acid diffusion and excellent solubility in solvents. Furthermore, those represented by formula (6') are particularly preferred because they have extremely low acid diffusion.

[0953] When the chemically amplified resist composition of the present invention contains (E) another photoacid generator, its content is preferably 0.1 to 40 parts by mass, and more preferably 0.5 to 20 parts by mass, relative to 80 parts by mass of the base polymer (B). The amount of the photoacid generator (E) added within the aforementioned range is preferred because it provides good resolution and eliminates the risk of foreign matter generation after development or during stripping of the resist film. The other photoacid generator (E) may be used alone or in combination of two or more.

[0954] [(F) Surfactant]

[0955] The chemically amplified resist composition of the present invention may further contain a surfactant as component (F). The surfactant (F) is preferably a surfactant that is insoluble or poorly soluble in water and soluble in an alkaline developer, or a surfactant that is insoluble or poorly soluble in both water and an alkaline developer. Such surfactants can be found in Japanese Patent Application Publication Nos. 2010-215608 and 2011-16746.

[0956] As for the surfactants that are insoluble or poorly soluble in water and alkaline developer, among the surfactants described in the aforementioned publication, suitable ones include FC-4430 (manufactured by 3M Co., Ltd.), SURFLON (registered trademark) S-381 (manufactured by AGC Seimi Chemical Co., Ltd.), OLFINE (registered trademark) E1004 (manufactured by Nissin Chemical Co., Ltd.), KH-20 and KH-30 (manufactured by AGC Seimi Chemical Co., Ltd.), and the oxetane ring-opening polymer represented by the following formula (surf-1).

[0957] [Chemistry 344]

[0958]

[0959] Here, R, Rf, A, B, C, m, and n are irrelevant to the above description and apply only to formula (surf-1). R is a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Examples of the aforementioned aliphatic group include ethylene, 1,4-butylene, 1,2-propylene, 2,2-dimethyl-1,3-propylene, and 1,5-pentylene. Examples of trivalent or tetravalent aliphatic groups include the following.

[0960] [Chemistry 345]

[0961]

[0962] In the formula, the dotted lines represent atomic bonds and are partial structures derived from glyceryl, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.

[0963] Among them, 1,4-butylene group, 2,2-dimethyl-1,3-propylene group, and the like are preferred.

[0964] Rf is a trifluoromethyl group or a pentafluoroethyl group, preferably a trifluoromethyl group. m is an integer from 0 to 3, n is an integer from 1 to 4, the sum of n and m is the valence of R, and is an integer from 2 to 4. A is 1. B is an integer from 2 to 25, preferably an integer from 4 to 20. C is an integer from 0 to 10, preferably 0 or 1. In addition, the arrangement of the constituent units in formula (surf-1) is not specified, and they may be bonded in blocks or randomly. For details on the production of surfactants based on partially fluorinated oxetane ring-opening polymers, see the specification of U.S. Patent No. 5,650,483.

[0965] Surfactants that are insoluble or poorly soluble in water but soluble in alkaline developers function to reduce water infiltration and leaching by aligning to the surface of the resist film when a resist overcoat is not used in ArF immersion lithography. This is useful for suppressing the elution of water-soluble components from the resist film and reducing damage to the exposure apparatus. Furthermore, they are useful for solubilizing during aqueous alkaline development after exposure or after a post-exposure bake (PEB), making them less likely to become foreign matter that can cause defects. Such surfactants are insoluble or poorly soluble in water but soluble in alkaline developers. These polymeric surfactants, also known as hydrophobic resins, are particularly preferred for their high water repellency and improved water-slip properties.

[0966] Specific examples of such polymeric surfactants include those containing at least one type of repeating unit selected from the group consisting of repeating units represented by any one of the following formulae (7A) to (7E).

[0967] [Chemistry 346]

[0968]

[0969] In formulas (7A) to (7E), R B W is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 It is -CH2-, -CH2CH2-, -O- or two -H separated from each other. s1 R are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. s2 is a single bond, or a linear or branched alkylene group having 1 to 5 carbon atoms. s3 R are each independently a hydrogen atom, a hydrocarbon group or a fluorinated hydrocarbon group having 1 to 15 carbon atoms, or an acid-labile group. s3 When it is a hydrocarbon group or a fluorinated hydrocarbon group, an ether bond or a carbonyl group may be inserted between carbon-carbon bonds. s4 is a (u+1)-valent hydrocarbon group or fluorinated hydrocarbon group having 1 to 20 carbon atoms. u is an integer of 1 to 3. s5 are independently a hydrogen atom, or -C(=O)-ORsa The group represented by R sa is a fluorinated hydrocarbon group having 1 to 20 carbon atoms. s6 It is a hydrocarbon group or a fluorinated hydrocarbon group having 1 to 15 carbon atoms, and an ether bond or a carbonyl group may be inserted between carbon-carbon bonds.

[0970] R s1 The hydrocarbon group having 1 to 10 carbon atoms represented by is preferably a saturated hydrocarbon group, and may be linear, branched, or cyclic. Specific examples 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 hydrocarbon groups having 3 to 10 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl. Among these, those having 1 to 6 carbon atoms are preferred.

[0971] R s2 The alkylene group represented by is preferably a saturated alkylene group, and may be linear, branched, or cyclic. Specific examples thereof include methylene, ethylene, propylene, butylene, and pentylene.

[0972] R s3 or R s6 The hydrocarbon group represented by may be saturated or unsaturated, and may be straight chain, branched, or cyclic. Specific examples thereof include saturated hydrocarbon groups, alkenyl groups, alkynyl groups, and other aliphatic unsaturated hydrocarbon groups, preferably saturated hydrocarbon groups. The aforementioned saturated hydrocarbon groups may be exemplified as R s1 In addition to the hydrocarbon group represented by R, there are undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl and the like. s3 or R s6 The fluorinated hydrocarbon groups represented by fluorinated hydrocarbon groups include groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the aforementioned hydrocarbon groups are substituted with fluorine atoms. As mentioned above, an ether bond or a carbonyl group may be inserted between the carbon-carbon bonds.

[0973] R s3 Specific examples of the acid-labile group include the groups represented by the aforementioned formulae (AL-3) to (AL-5), trialkylsilyl groups wherein each alkyl group is an alkyl group having 1 to 6 carbon atoms, and oxo groups containing alkyl groups having 4 to 20 carbon atoms.

[0974] R s4 The (u+1)-valent hydrocarbon group or fluorinated hydrocarbon group represented by may be linear, branched, or cyclic. Specific examples thereof include groups obtained by further removing u hydrogen atoms from the aforementioned hydrocarbon group or fluorinated hydrocarbon group.

[0975] R saThe fluorinated hydrocarbon group represented by is preferably saturated and may be linear, branched, or cyclic. Specific examples include those in which some or all of the hydrogen atoms of the aforementioned hydrocarbon groups are substituted with fluorine atoms, such as trifluoromethyl, 2,2,2-trifluoroethyl, 3,3,3-trifluoro-1-propyl, 3,3,3-trifluoro-2-propyl, 2,2,3,3-tetrafluoropropyl, 1,1,1,3,3,3-hexafluoroisopropyl, 2,2,3,3,4,4,4-heptafluorobutyl, 2,2,3,3,4,4,5,5-octafluoropentyl, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl, 2-(perfluorobutyl)ethyl, 2-(perfluorohexyl)ethyl, 2-(perfluorooctyl)ethyl, and 2-(perfluorodecyl)ethyl.

[0976] Specific examples of the repeating unit represented by any one of formulae (7A) to (7E) include the following, but are not limited thereto. B Same as above.

[0977] [Chemistry 347]

[0978]

[0979] [Chemistry 348]

[0980]

[0981] [Chemistry 349]

[0982]

[0983] [Chemistry 350]

[0984]

[0985] [Chemistry 351]

[0986]

[0987] [Chemistry 352]

[0988]

[0989] The aforementioned polymeric surfactant may further contain repeating units other than the repeating units represented by formulae (7A) to (7E). Examples of the other repeating units include repeating units derived from methacrylic acid, α-trifluoromethylacrylic acid derivatives, and the like. In the polymeric surfactant, the content of the repeating units represented by formulae (7A) to (7E) is preferably 20 mol% or more, more preferably 60 mol% or more, and even more preferably 100 mol% of the total repeating units.

[0990] The Mw of the polymeric surfactant is preferably 1,000 to 500,000, more preferably 3,000 to 100,000, and the Mw / Mn is preferably 1.0 to 2.0, more preferably 1.0 to 1.6.

[0991] Methods for synthesizing the aforementioned polymeric surfactants include: a method in which a monomer providing the repeating units represented by formulas (7A) to (7E) and, if necessary, other repeating units with unsaturated bonds is added to an organic solvent, heated, and polymerized. Examples of organic solvents used in the polymerization include toluene, benzene, THF, diethyl ether, and dioxane. Examples of polymerization initiators include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionic acid), benzoyl peroxide, and lauroyl peroxide. The reaction temperature is preferably 50-100°C. The reaction time is preferably 4-24 hours. The acid-labile group may be directly introduced into the monomer, or it may be protected or partially protected after polymerization.

[0992] When synthesizing the aforementioned 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 such chain transfer agent added is preferably 0.01 to 10 mol % relative to the total molar amount of the monomers to be polymerized.

[0993] When the chemically amplified resist composition of the present invention contains a surfactant (F), its content is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 10 parts by mass, relative to 80 parts by mass of the base polymer (B). When the surfactant (F) content is 0.1 parts by mass or greater, the receding contact angle of the resist film surface with water is sufficiently improved. When the surfactant (F) content is 50 parts by mass or less, the dissolution rate of the resist film surface in the developer is slow, and the height of the formed fine pattern is sufficiently preserved. The surfactant (F) may be used alone or in combination of two or more.

[0994] [(G) Other ingredients]

[0995] The chemically amplified resist composition of the present invention may also contain, as (G) other components, a compound that decomposes with acid to generate acid (acid multiplication compound), an organic acid derivative, a fluorinated alcohol, or a compound with an Mw of 3000 or less whose solubility in a developer changes due to the action of acid (dissolution inhibitor). The acid multiplication compound may be described in Japanese Patent Application Laid-Open No. 2009-269953 or Japanese Patent Application Laid-Open No. 2010-215608. When the acid multiplication compound is included, its content is preferably 0 to 5 parts by mass, more preferably 0 to 3 parts by mass, relative to 80 parts by mass of the base polymer (B). Excessive content may make it difficult to control acid diffusion, resulting in poor resolution and pattern shape. The organic acid derivative, fluorinated alcohol, and dissolution inhibitor may be described in Japanese Patent Application Laid-Open No. 2009-269953 or Japanese Patent Application Laid-Open No. 2010-215608.

[0996] [Pattern Formation Method]

[0997] The pattern forming method of the present invention comprises the following steps:

[0998] Using the chemically amplified resist composition to form a resist film on a substrate,

[0999] exposing the resist film to high-energy radiation, and

[1000] The exposed resist film is developed using a developer.

[1001] The aforementioned substrate can be used, for example: a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective film, etc.), or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.).

[1002] The resist film can be formed by applying the chemically amplified resist composition onto a substrate, for example, by spin coating to a film thickness of preferably 0.05 to 2 μm, and pre-baking the film on a hot plate at preferably 60 to 150° C. for 1 to 10 minutes, more preferably 80 to 140° C. for 1 to 5 minutes.

[1003] Examples of high-energy radiation used for exposure of the resist film include KrF excimer laser, ArF excimer laser, EB, and EUV with a wavelength of 3 to 15 nm. When KrF excimer laser, ArF excimer laser, or EUV is used for exposure, a mask for forming the desired pattern can be used, and the exposure dose is preferably 1 to 200 mJ / cm 2 More preferably, it is 10 to 100 mJ / cm 2When EB is used, a mask for forming a target pattern or a direct exposure dose of 1 to 300 μC / cm2 may be used. 2 More preferably, it is 10 to 200 μC / cm 2 way of irradiation.

[1004] In addition to the conventional exposure method, an immersion method in which a liquid having a refractive index of 1.0 or higher is inserted between the resist film and the projection lens can be used for exposure. In this case, a water-insoluble protective film can also be used.

[1005] The water-insoluble protective film is used to prevent elution from the resist film and improve the water slipperiness of the film surface. It can be roughly divided into two types. One is the organic solvent-removable type, which must be removed using an organic solvent that does not dissolve the resist film before alkaline aqueous solution development. The other is the alkaline aqueous solution-soluble type, which is soluble in an alkaline developer and removes the protective film simultaneously with the removal of the soluble portion of the resist film. The latter is particularly preferably based on a polymer containing a 1,1,1,3,3,3-hexafluoro-2-propanol residue that is insoluble in water but soluble in an alkaline developer and is soluble in alcoholic solvents with 4 or more carbon atoms, etheric solvents with 8 to 12 carbon atoms, or mixed solvents thereof. Alternatively, the water-insoluble, alkaline developer-soluble surfactant can be dissolved in an alcoholic solvent with 4 or more carbon atoms, etheric solvents with 8 to 12 carbon atoms, or mixed solvents thereof.

[1006] After exposure, PEB can be performed, for example, by heating on a hot plate at preferably 60 to 150° C. for 1 to 5 minutes, more preferably 80 to 140° C. for 1 to 3 minutes.

[1007] For development, for example, a developer containing an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH) preferably at a concentration of 0.1 to 5% by mass and more preferably at a concentration of 2 to 3% by mass is used, and development is performed using a common method such as a dip method, a puddle method, or a spray method for preferably 0.1 to 3 minutes and more preferably 0.5 to 2 minutes, whereby the exposed portion is dissolved and the intended pattern is formed on the substrate.

[1008] After the resist film is formed, pure water rinsing may be performed to extract the acid generator and the like from the film surface or to wash away particles. Rinsing may also be performed after exposure to remove water remaining on the film.

[1009] Alternatively, double patterning can be used for pattern formation. Examples of double patterning methods include a trench method in which a 1:3 groove pattern is formed by first exposure and etching, followed by a second exposure with a shifted position to form a 1:3 groove pattern, thereby forming a 1:1 pattern; and a line method in which a 1:3 isolated residual pattern is formed by first exposure and etching, followed by a second exposure with a shifted position to form a second 1:3 isolated residual pattern below the first base, thereby forming a 1:1 pattern with half the pitch.

[1010] In the pattern forming method of the present invention, a negative tone development method in which an organic solvent is used as a developer instead of the alkaline aqueous solution to dissolve the unexposed portion may be used.

[1011] In the above-mentioned organic solvent development, as a developer, the following can be used: 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, amyl acetate, butyl acetate, isoamyl acetate, propyl formate, butyl formate, isobutyl formate, amyl formate, isoamyl formate, methyl valerate, methyl pentenoate, crotonic acid methyl ester, ethyl crotonate, methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, amyl lactate, isoamyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, ethyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, 2-phenylethyl acetate, etc. These organic solvents may be used alone or in combination of two or more.

[1012] Example

[1013] Hereinafter, the present invention will be described in detail with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples.

[1014] IR: NICOLET 6700 manufactured by Thermo Fisher Scientific

[1015] · 1 H-NMR: ECA-500 manufactured by JEOL Ltd.

[1016] MALDI TOF-MS: S3000 manufactured by JEOL Ltd.

[1017] [1] Synthesis of onium salts

[1018] [Example 1-1] Synthesis of onium salt PAG-1

[1019] [Chemistry 353]

[1020]

[1021] (1) Synthesis of intermediate In-1

[1022] Under a nitrogen atmosphere, raw material SM-1 (6.3 g), raw material SM-2 (10.4 g), DMAP (0.3 g) and dichloromethane (50 g) were added to the reaction vessel and cooled with an ice bath. While maintaining the temperature in the reaction vessel below 20°C, hydrochloric acid-1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (5.8 g) was added in a powdered state. After addition, the temperature was raised to room temperature and matured for 12 hours. After maturation, water was added to stop the reaction, and a usual aqueous work-up was performed. After distilling the solvent, diisopropyl ether was added to wash the residue, thereby obtaining 14.4 g of intermediate In-1 (yield 92%) as an oily substance.

[1023] (2) Synthesis of PAG-1

[1024] Under a nitrogen atmosphere, intermediate In-1 (14.4 g), raw material SM-3 (7.8 g), dichloromethane (50 g), and water (30 g) were added. After stirring for 15 minutes, the organic layer was separated, washed with water, and then concentrated under reduced pressure. Methyl isobutyl ketone (50 g) was added to the concentrate, and azeotropic dehydration was performed. Diisopropyl ether was further added for crystallization, resulting in 16.0 g of the target compound PAG-1 as white crystals (yield 92%).

[1025] The IR spectrum data and TOF-MS results of PAG-1 are shown below. 1 The results of H-NMR / DMSO-d6) are as follows Figure 1 shown.

[1026] IR(D-ATR): ν=3484,3065,3024,2972,1779,1641,1593,1583,1479,1467,1443,1379,1324,127 2,1229,1170,1123,1091,1047,999,986,917,886,847,816,763,706,681,631,596,535,487cm -1 .

[1027] MALDI TOF-MS:POSITIVE M + 277 (equivalent to C 18 H 13 OS + )

[1028] NEGATIVE M - 477 (equivalent to C 23 H 13 F4O5S - )

[1029] [Examples 1-2 to 1-9] Synthesis of Onium Salts PAG-2 to PAG-9

[1030] Onium salts PAG-2 to PAG-9 represented by the following formulae were synthesized using corresponding raw materials and known organic synthesis reactions.

[1031] [Chemistry 354]

[1032]

[1033] [Chemistry 355]

[1034]

[1035] [2] Synthesis of base polymer

[1036] [Synthesis Example] Synthesis of base polymers (P-1 to P-5)

[1037] The monomers were combined and copolymerized in MEK as a solvent. The reaction solution was poured into hexane. The precipitated solid was washed with hexane, separated and dried to obtain base polymers (P-1 to P-5) with the following compositions. 1 The structure was confirmed by H-NMR, and the Mw and Mw / Mn were confirmed by GPC (solvent: THF, standard: polystyrene).

[1038] [Chemistry 356]

[1039]

[1040] [Chemistry 357]

[1041]

[1042] [3] Preparation of chemically amplified resist compositions

[1043] [Examples 2-1 to 2-30, Comparative Examples 1-1 to 1-20]

[1044] The photoacid generators (PAG-1 to PAG-9) composed of the onium salt of the present invention, comparative photoacid generators (PAG-A to PAG-E), other photoacid generators (PAG-X, PAG-Y), base polymers (P-1 to P-5), and quenchers (Q-1 to Q-4) were dissolved in a solvent containing 0.01% by mass of surfactant A (OMNOVA) according to the compositions shown in Tables 1 and 2 below to prepare solutions. The solutions were then filtered through a 0.2 μm Teflon (registered trademark) filter to prepare chemically amplified resist compositions (R-1 to R-30 and CR-1 to CR-20).

[1045] [Table 1]

[1046]

[1047] [Table 2]

[1048]

[1049] In Tables 1 and 2, the solvent, other photoacid generators PAG-X and PAG-Y, comparative photoacid generators PAG-A to PAG-E, quenchers Q-1 to Q-4, and surfactant A are as follows.

[1050] Solvent: PGMEA (propylene glycol monomethyl ether acetate)

[1051] DAA (Diacetone Alcohol)

[1052] Other photoacid generators: PAG-X, PAG-Y

[1053] [Chemistry 358]

[1054]

[1055] Comparative photoacid generators: PAG-A to PAG-E

[1056] [Chemistry 359]

[1057]

[1058] Quencher: Q-1~Q-4

[1059] [Hua360]

[1060]

[1061] Surfactant A: 3-methyl-3-(2,2,2-trifluoroethoxymethyl)oxetane, tetrahydrofuran, and 2,2-dimethyl-1,3-propanediol copolymer (manufactured by OMNOVA)

[1062] [Chemistry 361]

[1063]

[1064] a:(b+b'):(c+c')=1:4~7:0.01~1 (molar ratio)

[1065] Mw=1500

[1066] [4]EUV lithography evaluation (1)

[1067] [Examples 3-1 to 3-30, Comparative Examples 2-1 to 2-20]

[1068] Each chemically amplified resist composition (R-1 to R-30, CR-1 to CR-20) shown in Tables 1 and 2 was spin-coated onto a Si substrate on which a 20 nm thick silicon-containing spin-on hard mask SHB-A940 (silicon content: 43 mass%) manufactured by Shin-Etsu Chemical Co., Ltd. was formed. The film was pre-baked at 100°C for 60 seconds using a hot plate to form a 50 nm thick resist film. The resist film was exposed using an EUV scanning exposure system NXE3400 manufactured by ASML (NA 0.33, σ 0.9 / 0.6, dipole illumination) while varying the exposure dose and focus (exposure dose step: 1 mJ / cm 2 An LS pattern with a size of 18 nm and a pitch of 36 nm was exposed on the wafer while scanning electron microscopy (SEM) scanning at a focal pitch of 0.020 μm. After exposure, PEB was performed for 60 seconds at the temperatures shown in Tables 3 and 4. Subsequently, immersion development was performed for 30 seconds with a 2.38 mass% TMAH aqueous solution, followed by rinsing with a surfactant-containing rinse material and spin drying to obtain a positive pattern.

[1069] The obtained LS pattern was observed using a Hitachi High-Tech Co., Ltd. long-range SEM (CG6300), and the sensitivity, EL, LWR, depth of focus (DOF), and collapse limit were evaluated according to the following methods. The results are shown in Tables 3 and 4.

[1070] [Sensitivity evaluation]

[1071] Calculate the optimal exposure dose Eop (mJ / cm2) to obtain an LS pattern with a line width of 18 nm and a pitch of 36 nm. 2 ) and let it be the sensitivity. The smaller the value, the higher the sensitivity.

[1072] [EL evaluation]

[1073] The EL (unit: %) was calculated from the exposure amount formed within the range of ±10% (16.2 to 19.8 nm) of the 18 nm pitch width in the LS pattern using the following formula: The larger the value, the better the performance.

[1074] EL (%) = (|E1-E2| / Eop) × 100

[1075] E1: Provides the optimal exposure for LS patterns with a line width of 16.2nm and a pitch of 36nm

[1076] E2: Provides the optimal exposure for LS patterns with a line width of 19.8nm and a pitch of 36nm

[1077] Eop: Provides the optimal exposure for LS patterns with a line width of 18nm and a pitch of 36nm

[1078] [LWR evaluation]

[1079] The LS pattern obtained by irradiation with Eop is measured at 10 locations along the longitudinal direction of the line. From the results, the value (3σ) tripled by the standard deviation (σ) is calculated and designated as the LWR. The smaller this value, the less roughness there is, and a pattern with uniform line width can be obtained.

[1080] [DOF evaluation]

[1081] The depth of focus evaluation was performed by determining the focal range formed within the range of ±10% (16.2 to 19.8 nm) of the 18 nm size in the LS pattern. The larger the value, the wider the depth of focus.

[1082] [Evaluation of Collapse Limit of Line Pattern]

[1083] Measure the line size of the LS pattern at each exposure dose at optimal focus at 10 locations along the longitudinal direction. The thinnest line size that can be obtained without collapse is defined as the collapse limit size. The smaller this value, the better the collapse limit.

[1084] [Table 3]

[1085]

[1086] [Table 4]

[1087]

[1088] The results shown in Tables 3 and 4 demonstrate that the chemically amplified resist composition containing the photoacid generator composed of the onium salt of the present invention exhibits good sensitivity and excellent EL, LWR, and DOF. Furthermore, it was confirmed that the collapse threshold value is low, indicating strong pattern collapse resistance even during fine pattern formation. Therefore, the chemically amplified resist composition of the present invention is suitable as a material for EUV lithography.

[1089] [5]EUV lithography evaluation (2)

[1090] [Examples 4-1 to 4-30, Comparative Examples 3-1 to 3-20]

[1091] Each chemically amplified resist composition (R-1 to R-30, CR-1 to CR-20) shown in Tables 1 to 3 was spin-coated onto a Si substrate having a 20 nm thick film of a Shin-Etsu Chemical Co., Ltd. silicon-containing spin-on hard mask SHB-A940 (silicon content: 43 mass%). Prebaking was performed using a hot plate at 105°C for 60 seconds to form a 50 nm thick resist film. The resist film was exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadrupole illumination, mask with a hole pattern of 46 nm pitch and +20% offset on the wafer). PEB was performed using a hot plate for 60 seconds at the temperatures listed in Tables 7 and 8, and developed using a 2.38 mass% TMAH aqueous solution for 30 seconds to form a hole pattern of 23 nm in size.

[1092] Using a Hitachi High-Tech CG6300, we measured the exposure dose required to form a 23 nm hole, and defined this as the sensitivity. We also measured the dimensions of 50 holes at this point, and defined the value (3σ) of three times the standard deviation (σ) obtained from these measurements as the CDU. The results are shown in Tables 5 and 6.

[1093] [Table 5]

[1094]

[1095]

[1096] [Table 6]

[1097] Resist composition PEB temperature (℃) <![CDATA[Optimal exposure dose (mJ / cm 2 )]]> CDU(nm) Comparative Example 3-1 CR-1 90 26 2.9 Comparative Example 3-2 CR-2 90 26 2.7 Comparative Example 3-3 CR-3 85 27 3.1 Comparative Examples 3-4 CR-4 90 26 2.9 Comparative Examples 3-5 CR-5 95 25 3.1 Comparative Examples 3-6 CR-6 90 26 3.0 Comparative Examples 3-7 CR-7 85 27 2.9 Comparative Examples 3-8 CR-8 90 26 3.2 Comparative Examples 3-9 CR-9 90 27 2.8 Comparative Examples 3-10 CR-10 90 27 2.9 Comparative Examples 3-11 CR-11 85 28 3.1 Comparative Examples 3-12 CR-12 90 27 3.1 Comparative Examples 3-13 CR-13 90 27 3.0 Comparative Examples 3-14 CR-14 90 28 3.2 Comparative Examples 3-15 CR-15 90 29 2.8 Comparative Examples 3-16 CR-16 85 27 2.9 Comparative Example 3-17 CR-17 95 26 2.9 Comparative Example 3-18 CR-18 90 27 2.9 Comparative Example 3-19 CR-19 90 28 2.8 Comparative Example 3-20 CR-20 90 29 2.9

[1098] The results shown in Tables 5 and 6 confirm that the chemically amplified resist composition containing the photoacid generator composed of the onium salt of the present invention has good sensitivity and excellent CDU.

Claims

1. An onium salt represented by the following formula (1); Where R 1 ~R 12 are each independently a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom; R 13 and R 14 One of them is a group having a partial structure represented by the following formula (1a), and the other is a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom; Again, R 1 ~R 14 At least two of them may also be bonded to each other and form a ring together with the carbon atoms to which they are bonded, or form a ring together with the carbon atoms to which they are bonded and the carbon atoms between them; Z + is an onium cation; In the formula, m1 is 0 or 1; m2 is an integer from 0 to 4 when m1 is 0, and an integer from 0 to 6 when m1 is 1; m3 is an integer from 0 to 3 when m1 is 0, and an integer from 0 to 5 when m1 is 1; however, m2+m3 is 0 to 4 when m1 is 0, and is 0 to 6 when m1 is 1; R F is a fluorine atom, a fluorinated alkyl group having 1 to 6 carbon atoms, a fluorinated alkoxy group having 1 to 6 carbon atoms, or a fluorinated alkylthio group having 1 to 6 carbon atoms; R 15 is a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom, and when m3 is 2 or more, multiple R 15 They can also bond to each other and to the carbon atoms to which they are bonded to form rings; L A and L B are independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonate bond, a sulfonamide bond, a carbonate bond or a carbamate bond; X L It is a single bond or a alkylene group having 1 to 40 carbon atoms which may contain a heteroatom.

2. The onium salt according to claim 1, which is represented by the following formula (1A); Where R 1 ~R 13 、R 15 、L A 、X L 、R F , m1~m3 and Z + Same as above.

3. The onium salt according to claim 2, which is represented by the following formula (1B); Where R 5 、R 10 ~R 13 、R 15 、L A 、X L 、R F , m1~m3 and Z + Same as above; m4 and m5 are each independently an integer from 0 to 4; R 16 and R 17 are independently a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom; and when m4 is 2 or more, multiple R 16 They may also be bonded to each other and form a ring together with the carbon atoms to which they are bonded, or form a ring together with the carbon atoms to which they are bonded and the carbon atoms between them. When m5 is 2 or more, multiple R 17 They may also be bonded to each other and to form a ring together with the carbon atoms to which they are bonded, or to form a ring together with the carbon atoms to which they are bonded and the carbon atoms between them.

4. The onium salt according to claim 3, which is represented by the following formula (1C); Where R 5 、R 10 ~R 13 、R 16 、R 17 、L A 、X L , m4, m5 and Z + Same as above. The onium salt according to claim 1 , wherein Z + It is a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2); Where R ct1 ~R ct5 are independently a halogen atom or a hydrocarbon group having 1 to 30 carbon atoms which may contain a hetero atom; and R ct1 and R ct2 They may also bond to each other and to the sulfur atom to which they are bonded to form a ring. A photoacid generator comprising the onium salt according to any one of claims 1 to 5.

7. A chemically amplified resist composition comprising the photoacid generator according to claim 6.

8. The chemically amplified resist composition according to claim 7, comprising: The base polymer comprises a repeating unit represented by the following formula (a1); Where R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group; X 1 is a single bond, phenylene, naphthylene or *-C(=O)-OX 11 -, and the phenylene group or naphthylene group may be substituted by an alkoxy group having 1 to 10 carbon atoms or a halogen atom which may also contain a fluorine atom; X 11 It is a saturated alkylene group, phenylene group or naphthylene group having 1 to 10 carbon atoms, and the saturated alkylene group may also contain a hydroxyl group, an ether bond, an ester bond or a lactone ring; * represents an atomic bond to a carbon atom of the main chain; AL 1 It is an acid-labile group.

9. The chemically amplified resist composition according to claim 8, wherein The base polymer contains a repeating unit represented by the following formula (a2); Where R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group; X 2 It is a single bond or *-C(=O)-O-; * represents an atomic bond with a carbon atom of the main chain; R 21 is a halogen atom, a cyano group, a hydrocarbon group having 1 to 20 carbon atoms which may contain heteroatoms, a hydrocarbonoxy group having 1 to 20 carbon atoms which may contain heteroatoms, a hydrocarboncarbonyl group having 2 to 20 carbon atoms which may contain heteroatoms, a hydrocarboncarbonyloxy group having 2 to 20 carbon atoms which may contain heteroatoms, or a hydrocarbonoxycarbonyl group having 2 to 20 carbon atoms which may contain heteroatoms; AL 2 It is an acid-labile group; a is an integer from 0 to 4.

10. The chemically amplified resist composition according to claim 8, wherein The base polymer contains a repeating unit represented by the following formula (b1) or (b2); Where R A are independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group; Y 1 It is a single bond or *-C(=O)-O-; * represents an atomic bond with a carbon atom of the main chain; R 31 A group having 1 to 20 carbon atoms, or a structure containing at least one selected from the group consisting of a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-); R 32 is a halogen atom, a hydroxyl group, a nitro group, a hydrocarbon group having 1 to 20 carbon atoms which may contain heteroatoms, a hydrocarbonoxy group having 1 to 20 carbon atoms which may contain heteroatoms, a hydrocarboncarbonyl group having 2 to 20 carbon atoms which may contain heteroatoms, a hydrocarboncarbonyloxy group having 2 to 20 carbon atoms which may contain heteroatoms, or a hydrocarbonoxycarbonyl group having 2 to 20 carbon atoms which may contain heteroatoms; b is an integer from 1 to 4; c is an integer from 0 to 4; however, 1≤b+c≤5.

11. The chemically amplified resist composition according to claim 8, wherein The base polymer contains at least one selected from the group consisting of a repeating unit represented by the following formula (c1), a repeating unit represented by the following formula (c2), a repeating unit represented by the following formula (c3), and a repeating unit represented by the following formula (c4); Where R A are independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group; Z 1 is a single bond or a phenylene group; Z 2 *-C(=O)-OZ 21 -, *-C(=O)-NH-Z 21 -or*-OZ 21 -;Z 21 An aliphatic alkylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining them, and may also contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group; Z 3 are independently a single bond, a phenylene group, a naphthylene group or *-C(=O)-OZ 31 -;Z 31 An aliphatic alkylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, wherein the aliphatic alkylene group may also contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring; Z 4 are independently a single bond, **-Z 41 -C(=O)-O-, **-C(=O)-NH-Z 41 -or**-OZ 41 -;Z 41 is a hydrocarbon group having 1 to 20 carbon atoms which may also contain heteroatoms; Z 5 are independently a single bond, *-Z 51 -C(=O)-O-, *-C(=O)-NH-Z 51 -or*-OZ 51 -;Z 51 is a hydrocarbon group having 1 to 20 carbon atoms which may also contain heteroatoms; Z 6 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, phenylene substituted with trifluoromethyl, *-C(=O)-OZ 61 -, *-C(=O)-N(H)-Z 61 -or*-OZ 61 -;Z 61 It is an aliphatic alkylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may also contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group; * indicates the atomic bond with the carbon atom of the main chain; ** indicates the atomic bond with Z 3 atomic bonds; R 41 and R 42 are each independently a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom; and R 41 and R 42 They can also bond to each other and to the sulfur atoms to which they are bonded to form a ring; L 1 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond, or a carbamate bond; Rf 1 and Rf 2 are independently a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms; Rf 3 and Rf 4 are independently a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms; Rf 5 and Rf 6 are independently a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms; however, all Rf 5 and Rf 6 It will not be a hydrogen atom at the same time; M - It is a non-nucleophilic relative ion; A + is an onium cation; d is an integer from 0 to 3.

12. The chemically amplified resist composition according to claim 7, further comprising an organic solvent.

13. The chemically amplified resist composition according to claim 7, further comprising a quencher.

14. The chemically amplified resist composition according to claim 7, further comprising a photoacid generator other than the photoacid generator according to claim 6.

15. The chemically amplified resist composition according to claim 7, further comprising a surfactant.

16. A pattern forming method comprising the following steps: forming a resist film on a substrate using the chemically amplified resist composition according to claim 7, The resist film is exposed to high energy radiation, and The exposed resist film is developed using a developer.

17. The pattern forming method according to claim 16, wherein: The high-energy ray is KrF excimer laser, ArF excimer laser, electron beam or extreme ultraviolet ray with a wavelength of 3 to 15 nm.

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