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JP-2026076054-A - Sulfonium salt type monomer, polymer, chemically amplified resist composition, and patterning method

JP2026076054AJP 2026076054 AJP2026076054 AJP 2026076054AJP-2026076054-A

Abstract

[Problem] To provide a sulfonium salt type monomer used in a chemically amplified resist composition for photolithography using high-energy rays, which has excellent solvent solubility, high sensitivity and high contrast, excellent lithography performance such as EL, LWR, CDU, DOF, and is resistant to pattern deformation and etching even in fine pattern formation, a polymer containing repeating units derived from the sulfonium salt type monomer, a chemically amplified resist composition containing the polymer, and a pattern formation method using the chemically amplified resist composition. [Solution] A sulfonium salt type monomer represented by the following formula (a). [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 (17)

  1. A sulfonium salt type monomer represented by the following formula (a). (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. Z- is a carboxylic acid anion having an aromatic vinyl structure and an iodine atom.
  2. The sulfonium salt type monomer according to claim 1, which is represented by the following formula (a1). (In the formula, n2 to n4, n6 to n8, n10 to n12, R1 to R6 , and Z- are the same as described above.)
  3. The sulfonium salt type monomer according to claim 1, wherein Z- is an anion represented by the following formula (Z). (In the formula, m1 is 0 or 1. m2 is 0, 1, 2, 3 or 4. m3 is 0, 1, 2 or 3. m4 is 0 or 1. m5 is 0, 1, 2, 3 or 4. m6 is 0, 1, 2 or 3. m7 is 0 or 1. m8 is 1, 2, 3 or 4. m9 is 0, 1, 2 or 3. m10 is 0 or 1. m11 is 0 or The answer is 1. However, when m1 is 0, 0 ≤ m2 + m3 + m11 ≤ 4, and when m1 is 1, 0 ≤ m2 + m3 + m11 ≤ 6. When m4 is 0, 0 ≤ m5 + m6 ≤ 4, and when m4 is 1, 0 ≤ m5 + m6 ≤ 6. When m7 is 0, 0 ≤ m8 + m9 ≤ 5, and when m7 is 1, 0 ≤ m8 + m9 ≤ 7. Also, 1 ≤ m2 + m5 + m8 ≤ 4. RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R7 , R8 , and R9 are each independently a halogen atom other than an iodine atom, a nitro group, a cyano 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, a C1-C20 hydrocarbylthio group which may contain a heteroatom, or a C1-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. When m3 is 2 or 3, each R7 may be the same or different from each other, and two R7s may bond to each other to form a ring with the carbon atoms to which they are bonded. When m6 is 2 or 3, each R8 may be the same or different from each other, and two R8s may bond to each other to form a ring with the carbon atoms to which they are bonded. When m9 is 2 or 3, each R9 may be the same or different from each other, and two R9s may bond to each other to form a ring with the carbon atoms to which they are bonded. LA1 , LA2 , LB1 , and LB2 are each independently a single bond, an ether bond, a carbonyl group, an ester bond, a sulfonic acid ester bond, an amide bond, a sulfonic acid amide bond, a carbonate bond, or a carbamate bond. X L1 and X L2 are each independently a hydroxylene group having 1 to 40 carbon atoms, which may contain a single bond or a heteroatom.
  4. A sulfonium salt type quencher comprising a sulfonium salt type monomer according to any one of claims 1 to 3.
  5. A polymer comprising repeating units derived from the sulfonium salt type quencher described in claim 4.
  6. Furthermore, the polymer according to claim 5, comprising a repeating unit 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.) 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. X2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * 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 or more, each R 11 may be the same as or different from one another. AL1 and AL2 are, independently, acid-unstable groups. a1 is 0, 1, 2, 3, or 4.
  7. Furthermore, the polymer according to claim 5, comprising a repeating unit represented by the following formula (b3). (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.
  8. Furthermore, the polymer according to claim 5, comprising a repeating unit represented by the following formula (c). (In the formula, RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.) Y1 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain. R 21 is a C1-C20 hydrocarbyl group which may contain a halogen atom, a carboxyl group, a nitro group, a cyano group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. c1 is 1, 2, 3, or 4. c2 is 0, 1, 2, or 3, where 1 ≤ c1 + c2 ≤ 5.
  9. Furthermore, the polymer according to claim 5 comprises repeating units derived from an onium salt type monomer containing a polymerizable group and a fluorosulfonic acid anion having at least one iodine atom, and a sulfonium cation.
  10. Furthermore, the polymer according to claim 5, comprising a repeating unit represented by the following formula (e). (In the formula, RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.) Z1 is a single bond, a phenylene group, a naphthylene group, *-C(=O)-O- Z11- or *-C(=O)-NH- Z11- , 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. * represents a bond with a carbon atom of the main chain. Z11 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. R 51 is a group having 1 to 20 carbon atoms that includes at least one structure selected from a hydrogen atom, or 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)-).
  11. (A) A chemically amplified resist composition comprising a base polymer containing the polymer described in claim 5.
  12. Furthermore, the chemically amplified resist composition according to claim 11, further comprising (B) an organic solvent.
  13. Furthermore, the chemically amplified resist composition according to claim 11, comprising (C) a quencher.
  14. Furthermore, the chemically amplified resist composition according to claim 11, further comprising (D) an acid generator.
  15. Furthermore, the chemically amplified resist composition according to claim 11, further comprising (E) a surfactant.
  16. A pattern forming method comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition described in claim 11; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer.
  17. The pattern formation method according to claim 16, wherein the high-energy beam is ArF excimer laser light with a wavelength of 193 nm, KrF excimer laser light with a wavelength of 248 nm, an electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

Description

This invention relates to sulfonium salt type monomers, polymers, chemically amplified resist compositions, and patterning methods. With the increasing integration and speed of LSIs, the miniaturization of pattern rules is progressing rapidly. In particular, the expansion of the flash memory market and the increase in storage capacity are driving this miniaturization. As for cutting-edge miniaturization technologies, mass production of 65nm node devices using ArF lithography is underway, and preparations for mass production of next-generation 45nm node devices using ArF immersion lithography are progressing. For next-generation 32nm node devices, candidates and ongoing investigations are underway, including immersion lithography using ultra-high NA lenses combining a liquid with a higher refractive index than water, a high refractive index lens, and a high refractive index resist film; extreme ultraviolet (EUV) lithography at a wavelength of 13.5nm; and double exposure (double patterning lithography) using ArF lithography. As miniaturization progresses and approaches the diffraction limit of light, the contrast of light decreases. This decrease in light contrast leads to a reduction in the resolution of hole and trench patterns, as well as a decrease in the focus margin, in positive-type resist films. As patterns become finer, the line width roughness (LWR) of line patterns and the dimensional uniformity (CDU) of hole patterns are becoming problematic. The effects of uneven distribution and aggregation of base polymers and acid generators, as well as the effects of acid diffusion, have been pointed out. Furthermore, LWR tends to increase as the resist film thins, and the degradation of LWR due to thinning associated with increasing fineness is becoming a serious problem. In resist compositions for EUV lithography, it is necessary to simultaneously achieve high sensitivity, high resolution, and low low-wavelength (LWR). Shortening the acid diffusion distance reduces LWR but also lowers sensitivity. For example, lowering the post-exposure bake (PEB) temperature reduces LWR but lowers sensitivity. Increasing the amount of quencher added also reduces LWR but lowers sensitivity. It is necessary to overcome the trade-off relationship between sensitivity and LWR. To suppress acid diffusion, a resist compound containing repeating units derived from an onium salt of a polymerizable unsaturated sulfonic acid has been proposed (Patent Document 1). Such so-called polymer-bonded acid generators have the characteristic of very short acid diffusion because polymer-type sulfonic acid is generated upon exposure. Furthermore, sensitivity can be improved by increasing the proportion of the acid generator. While increasing the amount of additive-type acid generators also increases sensitivity, this also increases the acid diffusion distance. Since acids diffuse non-uniformly, increased acid diffusion degrades LWR and CDU. In terms of the balance between sensitivity, LWR, and CDU, polymer-type acid generators can be said to have superior capabilities. Because iodine atoms have a very high absorption rate of EUV light at a wavelength of 13.5 nm, the effect of generating secondary electrons from iodine atoms during exposure has been confirmed, making them a focus of attention in EUV lithography. Patent Document 2 describes a photoacid generator in which iodine atoms are introduced into an anion, and Patent Document 3 describes a photoacid generator containing a polymerizable group in which iodine atoms are introduced into an anion. While some improvement in lithography performance has been confirmed, iodine atoms do not have high solubility in organic solvents, raising concerns about precipitation in solvents. To further suppress acid diffusion, a resist composition has been proposed that uses a polymer bound type quencher containing repeating units derived from a sulfonium salt of a weak acid with a pKa of -0.8 or higher that has polymerizable groups (Patent Documents 4-7). Patent Document 4 lists carboxylic acids, sulfonamides, phenols, hexafluoroalcohols, etc., as examples of weak acids. Patent No. 4425776Patent No. 6720926Patent No. 6973274International Publication No. 2019/167737International Publication No. 2022/264845Japanese Patent Publication No. 2022-115072Patent No. 7433394 [Sulfonium salt type monomer] The sulfonium salt monomer of the present invention is represented by the following formula (a). In formula (a), n1 is either 0 or 1. When n1 is 0, it is a benzene ring; when n1 is 1, it is a naphthalene ring; however, from the viewpoint of solvent solubility, a benzene ring with n1 being 0 is preferred. n2 is either 0, 1, or 2. n3 is either 0, 1, or 2. n4 is either 0, 1, or 2. From the viewpoint of raw material procurement, n4 is preferably 0 or 1. However, when n1 is 0, 0 ≤ n2 + n3 + n4 ≤ 5, and when n1 is 1, 0 ≤ n2 + n3 + n4 ≤ 7. In formula (a), n5 is either 0 or 1. When n5 is 0, it is a benzene ring; when n5 is 1, i