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JP-2026076051-A - Sulfonium salt, chemically amplified resist composition, and patterning method

JP2026076051AJP 2026076051 AJP2026076051 AJP 2026076051AJP-2026076051-A

Abstract

[Problem] To provide an onium salt for use in a chemically amplified resist composition, a chemically amplified resist composition, and a pattern formation method that are highly sensitive, have excellent resolution, improve lithography performance such as LWR, CDU, EL, DOF, and suppress resist pattern deformation in photolithography using energy rays. [Solution] A sulfonium salt comprising a sulfonium cation and an aromatic carboxylic acid anion represented by the following formula (1A). [Selection Diagram] None

Inventors

  • 福島 将大

Assignees

  • 信越化学工業株式会社

Dates

Publication Date
20260511
Application Date
20241023

Claims (19)

  1. A sulfonium salt comprising a sulfonium cation represented by the following formula (1A) and an aromatic carboxylic acid anion represented by the following formula (1B). (In the formula, n1 is 0 or 1. n2 is 0, 1 or 2. n3 is 0, 1 or 2. n4 is 0, 1 or 2. However, when n1 is 0, 0 ≤ n2 + n3 + n4 ≤ 5, and when n1 is 1, 0 ≤ n2 + n3 + n4 ≤ 7. n5 is 0 or 1. n6 is 0, 1 or 2. n7 is 0, 1 or 2. n8 is 0, 1 or 2. However, when n5 is 0, 0 ≤ n6 + n7 + n8 ≤ 5, and when n5 is 1, then 0 ≤ n6 + n7 + n8 ≤ 7. n9 is 0 or 1. n10 is 0, 1 or 2. n11 is 0, 1 or 2. n12 is 0, 1 or 2. However, when n9 is 0, then 0 ≤ n10 + n11 + n12 ≤ 5, and when n9 is 1, then 0 ≤ n10 + n11 + n12 ≤ 7. Also, 1 ≤ n2 + n6 + n10 ≤ 6, and 1 ≤ n3 + n7 + n11 ≤ 6. R1 , R2 , and R3 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. When n3 is 2, each R1 may be the same as or different from the others. When n7 is 2, each R2 may be the same as or different from the others. When n11 is 2, each R3 may be the same as or different from the others. R4 , R5 , and R6 are each independently a halogen atom, a nitro group, a hydroxyl group, a carboxyl group, a C1-C20 hydrocarbyl group which may contain a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, or a C1-C20 hydrocarbylthio group which may contain a heteroatom. When n4 is 2, each R4 may be the same or different from each other, and two R4s may bond to each other to form a ring with the carbon atoms to which they are bonded. When n8 is 2, each R5 may be the same or different from each other, and two R5s may bond to each other to form a ring with the carbon atoms to which they are bonded. When n12 is 2, each R6 may be the same or different from each other, and two R6s may bond to each other to form a ring with the carbon atoms to which they are bonded. Furthermore, two of the three aromatic rings bonded to S + may bond to each other, forming a ring with the sulfur atom to which they are bonded. (In the equation, n11 is 0 or 1. n12 is 1, 2, 3 or 4. n13 is 0, 1 or 2. n14 is 0, 1, 2, 3 or 4. However, when n11 is 0, 2 ≤ n12 + n13 + n14 ≤ 5, and when n11 is 1, 2 ≤ n12 + n13 + n14 ≤ 7.) L A consists of a single bond, an oxygen atom, a sulfur atom, an ester bond, or a carbonate bond. When L A is a single bond, R 7 is a C1-C20 hydrocarbyl group which may contain a hydrogen atom or a heteroatom; when L A is an oxygen atom, a sulfur atom, an ester bond, or a carbonate bond, R 7 is a C1-C20 hydrocarbyl group which may contain a hydrogen atom or a heteroatom (excluding acid-unstable groups) or an acid-unstable group. R8 is a halogen atom other than iodine, a nitro group, a cyano group, a C1-C20 hydrocarbyl group which may contain a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, or a C1-C20 hydrocarbylthio group which may contain a heteroatom. When n14 is 2, 3, or 4, multiple R8s may bond to each other, forming a ring structure with the carbon atoms on the aromatic ring to which they are bonded, and some of the -CH2- in the ring may be substituted with -O- or -S-.
  2. The sulfonium salt according to claim 1, wherein the sulfonium cation is represented by the following formula (1A-1). (In the formula, n2 to n4, n6 to n8, n10 to n12 and R1 to R6 are the same as described above.)
  3. The sulfonium salt according to claim 1, wherein the aromatic carboxylic acid anion is represented by the following formula (1B-1). (In the formula, n12 to n14, L A , R 7 and R 8 are the same as described above.)
  4. The sulfonium salt according to claim 1, wherein L A is an oxygen atom or an ester bond.
  5. The sulfonium salt according to claim 1, wherein L A is an oxygen atom, a sulfur atom, an ester bond, or a carbonate bond, and R 3 is an acid-unstable group.
  6. The sulfonium salt according to claim 1, wherein the acid-unstable group is represented by the following formula (AL-1) or (AL-2). (In the formula, p1 and p2 are independently 0 or 1. Q1 and q2 are independently 0, 1, 2, 3, or 4.) RL1 , RL2 , and RL3 are each independently a C1-C12 hydrocarbyl group, and some of the -CH2- of the hydrocarbyl group may be substituted with -O- or -S-. If the hydrocarbyl group includes an aromatic ring, some or all of the hydrogen atoms of the aromatic ring may be substituted with a halogen atom, a cyano group, a nitro group, a C1-C4 alkyl group which may contain a halogen atom, or a C1-C4 alkoxy group which may contain a halogen atom. Furthermore, RL1 and RL2 may bond to each other to form a ring with the carbon atom to which they are bonded, and some of the -CH2- of the ring may be substituted with -O- or -S-. RL4 and RL5 are each independently a hydrogen atom or a C1-C10 hydrocarbyl group. RL6 is a C1-C20 hydrocarbyl group, and some of the -CH2- in the hydrocarbyl group may be substituted with -O- or -S-. Furthermore, RL5 and RL6 may bond to each other to form a C3-C20 heterocyclic group with the carbon atoms and LB to which they are bonded, and some of the -CH2- in the heterocyclic group may be substituted with -O- or -S-. LB is either -O- or -S-. R La to R Ld are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom or a heteroatom. * indicates a bond with an adjacent oxygen or sulfur atom.
  7. A quencher comprising a sulfonium salt according to any one of claims 1 to 6.
  8. A chemically amplified resist composition comprising the quencher described in claim 7.
  9. A chemically amplified resist composition according to claim 8, comprising a base polymer containing a polymer having repeating units represented by the following formula (a1). (In the formula, RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.) X1 is a single bond, a phenylene group, a naphthylene group, *-C(=O)-O- X11- or *-C(=O)-NH- X11- , and the phenylene group or naphthylene group may be substituted with a hydroxyl group, a nitro group, a cyano group, a saturated hydrocarbyl group having 1 to 10 carbon atoms which may contain a fluorine atom, a saturated hydrocarbyloxy group having 1 to 10 carbon atoms which may contain a fluorine atom, or a halogen atom. X11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. * represents a bond with a carbon atom of the main chain. AL1 is an acid-unstable group.
  10. The chemically amplified resist composition according to claim 9, wherein the base polymer comprises repeating units represented by the following formula (a2). (In the formula, RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.) X² is either a single bond or an *-C(=O)-O- bond. * represents a bond with a carbon atom in the main chain. R 11 is a halogen atom, a cyano group, a hydroxyl group, a nitro group, a C1-C20 hydrocarbyl group which may contain a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. When a1 is 2, 3, or 4, each R 11 may be the same as or different from one another. AL2 is an acid-unstable group. (a is 0, 1, 2, 3, or 4.)
  11. The chemically amplified resist composition according to claim 9, wherein the base polymer comprises repeating units represented by the following formula (a3). (In the formula, b1 is 0 or 1. When b1 is 0, b2 is 0, 1, 2 or 3, and when b1 is 1, b2 is 0, 1, 2, 3, 4 or 5.) RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X3 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain. X4 is a single bond, an aliphatic hydrocarbylene group having 1 to 4 carbon atoms, a carbonyl group, a sulfonyl group, or a group obtained by combining these. X5 and X6 are, independently, either an oxygen atom or a sulfur atom, except that X4 and X6 are bonded to adjacent carbon atoms in the aromatic ring. R12 and R13 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom or a heteroatom. Furthermore, R12 and R13 may bond to each other to form a ring with the carbon atoms to which they are bonded. R 14 is a halogen atom, a hydroxyl group, a cyano group, a nitro group, a C1-C20 hydrocarbyl group which may contain a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom, a C1-C20 hydrocarbylthio group which may contain a heteroatom, or -N(R 14A )(R 14B ). R 14A and R 14B are each independently a hydrogen atom or a C1-C6 hydrocarbyl group. When b2 is 2 or more, each R 14 may be the same or different from each other, and multiple R 14s may bond to each other to form a ring with the carbon atoms of the aromatic ring to which they are bonded.
  12. The chemically amplified resist composition according to claim 9, wherein the base polymer comprises repeating units represented by the following formula (b1) or (b2). (In the formula, R A is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.) Y1 is either a single bond or an *-C(=O)-O- bond. * represents a bond with a carbon atom in the main chain. R 21 is a group having 1 to 20 carbon atoms that includes a hydrogen atom or at least one structure selected from a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride (-C(=O)-O-C(=O)-). R 22 is a halogen atom, a carboxyl group, a nitro group, a cyano group, a C1-C20 hydrocarbyl group which may contain a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. When c2 is 2, 3, or 4, each R 22 may be the same as or different from one another. c1 is 1, 2, 3, or 4. c2 is 0, 1, 2, 3, or 4, where 1 ≤ c1 + c2 ≤ 5.
  13. The chemically amplified resist composition according to claim 9, wherein the base polymer comprises at least one selected from repeating units represented by the following formula (c1), repeating units represented by the following formula (c2), repeating units represented by the following formula (c3), repeating units represented by the following formula (c4), and repeating units represented by the following formula (c5). (In the formula, d1 and d2 are independently 0, 1, 2, or 3. e1 is 0 or 1. e2 is 0, 1, 2, 3, or 4. e3 is 0, 1, 2, 3, or 4. However, when e1 is 0, 0 ≤ e2 + e3 ≤ 4, and when e1 is 1, 0 ≤ e2 + e3 ≤ 6.) R and A are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z1 is a phenylene group which may have a single bond or a substituent. Z2 is a single bond, **-C(=O)-O- Z21- , **-C(=O)-NH- Z21- , or **-O- Z21- . Z21 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a halogen atom, a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. Z3 is a single bond, ether bond, ester bond, amide bond, sulfonic acid ester bond, sulfonamide bond, carbonate bond, or carbamate bond. Z4 is a single bond, or a divalent group obtained by combining an aliphatic hydrocarbylene group, a phenylene group, or a combination thereof, and may contain a halogen atom, a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. Z 5 is independently a single bond, a phenylene group which may have substituents, a naphthylene group which may have substituents, or *-C(=O)-O-Z 51- . Z 51 is an aliphatic hydrocarbylene group, a phenylene group which may have 1 to 10 carbon atoms, and the aliphatic hydrocarbylene group may contain a halogen atom, a hydroxyl group which may have ether bonds which may have ester bonds which may have lactone rings. Z6 is a single bond, ether bond, ester bond, amide bond, sulfonic acid ester bond, sulfonamide bond, carbonate bond, or carbamate bond. Each Z7 is independently a single bond, ***- Z71 -C(=O)-O-, ***-C(=O)-NH- Z71- , or ***-O- Z71- . Z71 is a hydroxylene group having 1 to 20 carbon atoms, which may contain heteroatoms. Each Z8 is independently a single bond, ****- Z81 -C(=O)-O-, ****-C(=O)-NH- Z81- , or ****-O- Z81- . Z81 is a hydroxylene group having 1 to 20 carbon atoms, which may contain heteroatoms. Z9 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, *-C(=O)-O- Z91- , *-C(=O)-N(H) -Z91- , or *-O- Z91- . Z91 is a phenylene group substituted with an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. * represents a bond with a carbon atom in the main chain. ** represents a bond with Z1 . *** represents a bond with Z6 . **** represents a bond with Z7 . L1 is a single bond, ether bond, ester bond, carbonyl group, sulfonic acid ester bond, sulfonamide bond, carbonate bond, or carbamate bond. Rf 1 and Rf 2 are, independently, a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf3 and Rf4 are, independently, a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 are, independently, a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. However, not all of Rf 5 and Rf 6 are hydrogen atoms at the same time. Rf 7 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 31 and R 32 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. Furthermore, R 31 and R 32 may bond to each other, forming a ring with the sulfur atom to which they are bonded. R 33 is a C1-C20 hydrocarbyl group which may contain halogen atoms other than fluorine atoms, or heteroatoms. When e3 is 2, 3, or 4, each R 33 may be the same or different from each other, and multiple R 33s may bond to each other to form a ring with the carbon atoms to which they are bonded. M- is a non-nucleophilic counterion. A + is an onium cation.
  14. Furthermore, the chemically amplified resist composition according to claim 8, further comprising an organic solvent.
  15. Furthermore, the chemically amplified resist composition according to claim 8, comprising a photoacid generator that produces a strong acid.
  16. Furthermore, the chemical amplification resist composition according to claim 8, comprising a quencher other than the quencher described in claim 7.
  17. Furthermore, the chemically amplified resist composition according to claim 8, comprising a surfactant.
  18. A pattern forming method comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition described in claim 8; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer.
  19. The pattern formation method according to claim 18, wherein the high-energy beam is a KrF excimer laser beam, an ArF excimer laser beam, an electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

Description

This invention relates to sulfonium salts, chemically amplified resist compositions, and patterning methods. With the increasing integration and speed of LSIs, the miniaturization of pattern rules is progressing rapidly. This is because the proliferation of 5G high-speed communication and artificial intelligence (AI) necessitates high-performance devices to process them. At the forefront of miniaturization technology, mass production of 5nm node devices is underway using extreme ultraviolet (EUV) lithography with a wavelength of 13.5nm. Furthermore, research using EUV lithography is progressing for next-generation 3nm node and even the following-generation 2nm node devices. As miniaturization progresses, image blurring due to acid diffusion is becoming a problem. To ensure resolution in fine patterns of 45 nm and beyond, it has been suggested that controlling acid diffusion is crucial, in addition to improving dissolution contrast as previously proposed (Non-Patent Literature 1). However, since chemically amplified resist compositions increase sensitivity and contrast through acid diffusion, attempting to suppress acid diffusion to the extreme by lowering the post-exposure bake (PEB) temperature or shortening the time results in a significant decrease in sensitivity and contrast. The relationship between sensitivity, resolution, and line width roughness (LWR) in a triangle trade-off is shown. Improving resolution requires suppressing acid diffusion, but reducing the acid diffusion distance decreases sensitivity. Adding an acid generator that produces bulky acids to suppress acid diffusion is effective. Therefore, it has been proposed to incorporate repeating units derived from onium salts having polymerizable unsaturated bonds into the polymer. In this case, the polymer also functions as an acid generator (polymer-bound type acid generator). Patent Document 1 proposes sulfonium salts and iodonium salts having polymerizable unsaturated bonds that generate specific sulfonic acids. Patent Document 2 proposes sulfonium salts in which sulfonic acids are directly linked to the main chain. The acid-unstable groups used in (meth)acrylate polymers for ArF resist compositions undergo a deprotection reaction by using an acid generator that produces sulfonic acid with a fluorine atom substituted at the α-position. However, the deprotection reaction does not proceed with acid generators that produce sulfonic acid or carboxylic acid without a fluorine atom substituted at the α-position. When a sulfonium salt or iodonium salt that produces sulfonic acid with a fluorine atom substituted at the α-position is mixed with a sulfonium salt or iodonium salt that produces sulfonic acid without a fluorine atom substituted at the α-position, the sulfonium salt or iodonium salt that produces sulfonic acid without a fluorine atom substituted at the α-position undergoes ion exchange with the sulfonic acid with a fluorine atom substituted at the α-position. Since the sulfonic acid with a fluorine atom substituted at the α-position generated by light reverts back to the sulfonium salt or iodonium salt through ion exchange, the sulfonium salt or iodonium salt of sulfonic acid or carboxylic acid without a fluorine atom substituted at the α-position functions as a quencher. A resist composition using a sulfonium or iodonium salt that generates a carboxylic acid as a quencher has been proposed (Patent Document 3). Sulfonium salt type quenchers that generate carboxylic acids have been proposed. For example, sulfonium salts of salicylic acid and β-hydroxycarboxylic acid (Patent Document 4), salicylic acid derivatives (Patent Documents 5 and 6), fluorosalicylic acid (Patent Document 7), hydroxynaphthoic acid (Patent Document 8), salicylic acid with iodine-containing aromatic substituents (Patent Document 9), and salicylic acid with a cyclic acetal structure (Patent Document 10) have been proposed. In particular, salicylic acid is highly effective in suppressing acid diffusion through intramolecular hydrogen bonding between the carboxyl and hydroxyl groups. It has been pointed out that quencher aggregation reduces the dimensional uniformity (CDU) of the resist pattern. Preventing quencher aggregation in the resist film and homogenizing its distribution is expected to improve the dimensional uniformity of the pattern after development. In response to the demand for further miniaturization, a challenge remains: swelling occurs during alkaline development, particularly in positive-type resists, due to the developer, leading to pattern collapse during fine pattern formation. To address these miniaturization challenges, the development of novel materials for resist compositions is crucial. There is a need for an onium salt-type quencher that exhibits good sensitivity, sufficient acid diffusion control, excellent solvent solubility, and effective pattern collapse suppression. Japanese Patent Publication No. 2006-45311Japanese Patent Publication No. 2