# US 10,120,278 B2 · Carboxylic acid onium salt, chemically amplified resist composition, and pattern forming process

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- Number: US 10,120,278 B2
- Document ID: US10120278B2
- Status: Granted
- Kind: B2
- Application number: 15/488,774
- Filed: 2017-04-17
- Published: 2017-11-02
- Granted: 2018-11-06
- Earliest claimed: 2016-04-28
- Assignees: Shin-Etsu Chemical Co., Ltd.
- Applicants: Shin-Etsu Chemical Co., Ltd.
- Inventors: Masahiro Fukushima; Kazuhiro Katayama
- Web page: https://patentgrep.com/patent/US10120278B2

## CPC

- G03F 7/0045: {with organic non-macromolecular light-sensitive compounds not otherwise provided for, e.g. dissolution inhibitors}
- C07C 59/115: containing halogen
- C07C 69/753: of polycyclic acids
- C07C 271/24: with the nitrogen atom of at least one of the carbamate groups bound to a carbon atom of a ring other than a six-membered aromatic ring
- C07C 381/12: Sulfonium compounds
- C07D 307/00: Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
- C07D 493/18: Bridged systems
- G03F 7/0046: {with perfluoro compounds, e.g. for dry lithography (G03F7/0048 takes precedence)}
- G03F 7/0048: {characterised by the solvents or agents facilitating spreading, e.g. tensio-active agents}
- G03F 7/0382: {the macromolecular compound being present in a chemically amplified negative photoresist composition}
- G03F 7/0397: {the macromolecular compound having an alicyclic moiety in a side chain}
- G03F 7/091: {characterised by antireflection means or light filtering or absorbing means, e.g. anti-halation, contrast enhancement}
- G03F 7/11: having cover layers or intermediate layers, e.g. subbing layers {(G03F7/091 - G03F7/093, B41N3/03 take precedence)}
- G03F 7/162: {Coating on a rotating support, e.g. using a whirler or a spinner}
- G03F 7/168: {Finishing the coated layer, e.g. drying, baking, soaking}
- G03F 7/2006: {using coherent light; using polarised light}
- G03F 7/2041: {in the presence of a fluid, e.g. immersion; using fluid cooling means}
- G03F 7/322: {Aqueous alkaline compositions}
- G03F 7/325: {Non-aqueous compositions}
- G03F 7/38: Treatment before imagewise removal, e.g. prebaking {(G03F7/265 takes precedence)}
- C07C 2601/14: The ring being saturated
- C07C 2603/68: Dicyclopentadienes; Hydrogenated dicyclopentadienes
- C07C 2603/74: Adamantanes
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)

## Abstract

A carboxylic acid onium salt of formula (1) exerts a satisfactory acid diffusion control (or quencher) function. A resist composition comprising the carboxylic acid onium salt can be processed by DUV or EUV lithography to form a resist pattern with improved resolution, reduced LWR and minimal defects after development.

## Claims

### Claim 1

A carboxylic acid onium salt having the formula (1):
wherein R0 is hydrogen, or a C1-C20 straight, branched or cyclic monovalent hydrocarbon group which may contain a heteroatom,
R1 and R2 are each independently hydrogen, or a C1-C20 straight, branched or cyclic monovalent hydrocarbon group which may contain a hydroxyl moiety, cyano moiety, carbonyl moiety, ether bond, ester bond, sulfonate bond, carbonate bond, lactone ring, sultone ring, or carboxylic anhydride, or R1 and R2 may bond together to form a ring with the carbon atom to which they are attached,
Rf1 and Rf2 are each independently fluorine or a C1-C6 perfluoroalkyl group,
LA is a single bond or forms an ester bond, sulfonate bond, carbonate bond or carbamate bond with the vicinal oxygen atom,
Z+ is a sulfonium cation having the formula (2) or an iodonium cation having the formula (3):
wherein R11, R12 and R13 are each independently a C1-C20 straight, branched or cyclic monovalent hydrocarbon group which may contain a heteroatom, any two of R11, R12 and R13 may bond together to form a ring with the sulfur atom in the formula, R14 and R15 are each independently a C1-C20 straight, branched or cyclic monovalent hydrocarbon group which may contain a heteroatom.

### Claim 2 (depends on 1)

The onium salt of claim 1 wherein Rf1 and Rf2 are trifluoromethyl.

### Claim 3 (depends on 1)

The onium salt of claim 1 wherein Z+ is a sulfonium cation of formula (2).

### Claim 4 (depends on 1)

The onium salt of claim 1 wherein LA is a single bond or forms a sulfonate bond with the vicinal oxygen atom.

### Claim 5 (depends on 1)

The onium salt of claim 1 wherein LA is a single bond and R0 is hydrogen.

### Claim 6 (depends on 1)

The onium salt of claim 1 wherein the anion moiety of the onium salt is selected from the group consisting of the following formulae:

### Claim 7 (depends on 1)

An acid diffusion inhibitor comprising the carboxylic acid onium salt of claim 1.

### Claim 8 (depends on 7)

A chemically amplified resist composition comprising (A) the acid diffusion inhibitor of claim 7, (B) a base resin, (C) a photoacid generator, and (D) an organic solvent, wherein
said base resin contains a polymer comprising recurring units having the formula (a) and recurring units having the formula (b):
wherein RA is hydrogen, methyl or trifluoromethyl, ZA is a single bond, phenylene, naphthylene or (backbone)—C(═O)—O—Z′—, Z′ is a C1-C10 straight, branched or cyclic alkylene group which may contain a hydroxyl moiety, ether bond, ester bond, or lactone ring, or a phenylene or naphthylene group, XA is an acid labile group, and YA is hydrogen or a polar group having at least one structure selected from the group consisting of hydroxyl, cyano, carbonyl, carboxyl, ether bond, ester bond, sulfonate bond, carbonate bond, lactone ring, sultone ring, and carboxylic anhydride.

### Claim 9 (depends on 8)

The resist composition of claim 8 wherein said polymer further comprises recurring units of at least one type selected from recurring units having the formulae (c1) to (c3):
wherein RA is as defined above,
R21 is a single bond, phenylene, —O—R31—, or —C(═O)—Z22—R31—, Z22 is —O— or —NH—, R31 is a C1-C6 straight, branched or cyclic alkylene group, C2-C6 straight, branched or cyclic alkenylene group or phenylene group, which may contain a carbonyl (—CO—), ester (—COO—), ether (—O—) or hydroxyl moiety,
LB is a single bond or —Z33—C(═O)—O—, Z33 is a C1-C20 straight, branched or cyclic divalent hydrocarbon group which may contain a heteroatom,
Z11 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, —O—R32—, or —C(═O)—Z44—R32—, Z44 is —O— or —NH—, R32 is a C1C6 straight, branched or cyclic alkylene, C2-C6 straight, branched or cyclic alkenylene or phenylene group, which may contain a carbonyl, ester, ether or hydroxyl moiety,
R22 to R26 are each independently a C1-C20 straight, branched or cyclic monovalent hydrocarbon group which may contain a heteroatom, or any two of R21, R22 and R23 may bond together to form a ring with the sulfur atom in the formula, any two of R24, R25 and R26 may bond together to form a ring with the sulfur atom in the formula, and
M− is a non-nucleophilic counter ion.

### Claim 10 (depends on 8)

The resist composition of claim 8 wherein component (C) is a photoacid generator having the formula (4) or (5):
wherein R101, R102 and R103 are each independently a C1-C20 straight, branched or cyclic monovalent hydrocarbon group which may contain a heteroatom, any two of R101, R102 and R103 may bond together to form a ring with the sulfur atom to which they are attached, and X− is an anion selected from the formulae (4A) to (4D):
wherein Rfa, Rfb1, Rfb2, Rfc1, Rfc2, and Rfc3 are each independently fluorine or a C1-C40 straight, branched or cyclic monovalent hydrocarbon group which may contain a heteroatom, Rfb1 and Rfb2, or Rfc1 and Rfc2 may bond together to form a ring with the carbon atoms to which they are attached and the carbon atom therebetween, Rfd is a C1-C40 straight, branched or cyclic monovalent hydrocarbon group which may contain a heteroatom,
wherein R104 and R105 are each independently a C1-C30 straight, branched or cyclic monovalent hydrocarbon group which may contain a heteroatom, R106 is a C1-C30 straight, branched or cyclic divalent hydrocarbon group which may contain a heteroatom, any two of R104, R105 and R106 may bond together to form a ring with the sulfur atom to which they are attached, LC is a single bond, ether bond, or a C1-C20 straight, branched or cyclic divalent hydrocarbon group which may contain a heteroatom, X1, X2, X3 and X4 are each independently hydrogen, fluorine or trifluoromethyl, with the proviso that at least one of X1, X2, X3 and X4 is a substituent other than hydrogen, and k is an integer of 1 to 3.

### Claim 11 (depends on 8)

The resist composition of claim 8, further comprising (E) a nitrogen-containing compound.

### Claim 12 (depends on 8)

The resist composition of claim 8, further comprising (F) a surfactant which is insoluble or substantially insoluble in water and soluble in alkaline developer and/or a surfactant which is insoluble or substantially insoluble in water and alkaline developer.

### Claim 13 (depends on 8)

A pattern forming process comprising the steps of applying the chemically amplified resist composition of claim 8 onto a substrate, prebaking to form a resist film, exposing the resist film to KrF excimer laser, ArF excimer laser, EB or EUV through a photomask, baking, and developing the exposed resist film in a developer.

### Claim 14 (depends on 13)

The pattern forming process of claim 13 wherein the exposing step is by immersion lithography wherein a liquid having a refractive index of at least 1.0 is interposed between the resist film and a projection lens.

### Claim 15 (depends on 14)

The pattern forming process of claim 14, further comprising the step of forming a protective film on the resist film, and in the immersion lithography, the liquid is interposed between the protective firm and the projection lens.