# US 8,785,105 B2 · Sulfonium salt-containing polymer, resist composition, patterning process, and sulfonium salt monomer and making method

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- Number: US 8,785,105 B2
- Document ID: US8785105B2
- Status: Granted
- Kind: B2
- Application number: 13/292,127
- Filed: 2011-11-09
- Published: 2012-05-24
- Granted: 2014-07-22
- Earliest claimed: 2010-11-19
- Assignees: Shin-Etsu Chemical Co., Ltd.
- Applicants: Youichi Ohsawa; Masaki Ohashi; Seiichiro Tachibana; Jun Hatakeyama
- Inventors: Youichi Ohsawa; Masaki Ohashi; Seiichiro Tachibana; Jun Hatakeyama
- Web page: https://patentgrep.com/patent/US8785105B2

## CPC

- C08F 220/1818: {C13or longer chain (meth)acrylate, e.g. stearyl (meth)acrylate}
- C07C 69/54: Acrylic acid esters; Methacrylic acid esters
- C07C 303/32: of salts of sulfonic acids
- C07C 309/12: containing esterified hydroxy groups bound to the carbon skeleton
- C07C 309/20: of an acyclic unsaturated carbon skeleton
- C07C 381/12: Sulfonium compounds
- C08F 20/38: Esters containing sulfur
- C08F 220/24: containing perhaloalkyl radicals
- C08F 228/02: by a bond to sulfur
- G03F 7/0045: {with organic non-macromolecular light-sensitive compounds not otherwise provided for, e.g. dissolution inhibitors}
- G03F 7/0046: {with perfluoro compounds, e.g. for dry lithography (G03F7/0048 takes precedence)}
- G03F 7/0392: {the macromolecular compound being present in a chemically amplified positive photoresist composition}
- G03F 7/0397: {the macromolecular compound having an alicyclic moiety in a side chain}
- G03F 7/2041: {in the presence of a fluid, e.g. immersion; using fluid cooling means}
- G03F 7/38: Treatment before imagewise removal, e.g. prebaking {(G03F7/265 takes precedence)}
- C08F 220/382: {and containing oxygen, e.g. 2-sulfoethyl (meth)acrylate}
- Y10S 430/106: Binder containing
- Y10S 430/111: Polymer of unsaturated acid or ester
- Y10S 430/122: Sulfur compound containing
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- 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)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A sulfonium salt having a 4-fluorophenyl group is introduced as recurring units into a polymer comprising hydroxyphenyl (meth)acrylate units and acid labile group-containing (meth)acrylate units to form a polymer which is useful as a base resin in a resist composition. The resist composition has a high sensitivity, high resolution and minimized LER.

## Claims

### Claim 1

A polymer comprising recurring units having the general formulae (1a), (2), and (3):
wherein
R1 is hydrogen, fluorine, methyl or trifluoromethyl,
R2, R3, and R4 are each independently a substituted or unsubstituted, straight or branched C1-C10 alkyl, alkenyl or oxoalkyl group, a substituted or unsubstituted C6-C18 aryl, aralkyl or aryloxoalkyl group, or 4-fluorophenyl group, any two of R2, R3, and R4 may bond together to form a ring with the sulfur atom, with the proviso that at least one of R2, R3, and R4 is a 4-fluorophenyl group,
n is an integer of 0 to 2,
R8 is hydrogen or a C1-C10 alkyl group,
p is 0 or 1,
B is a single bond or a C1-C10 divalent organic group which may be substituted with an oxygen atom,
a is an integer of 0 to 3,
b is an integer of 1 to 3, and
X is an acid labile group.

### Claim 2 (depends on 1)

The polymer of claim 1, further comprising recurring units of at least one type selected from the general formulae (4), (5), and (6):
wherein
R1 is hydrogen, fluorine, methyl or trifluoromethyl,
R6 and R7 are each independently hydrogen or hydroxyl,
Y is a substituent group having lactone structure,
Z is hydrogen, a C1-C15 fluoroalkyl group or C1-C15 fluoroalcohol-containing substituent group.

### Claim 3 (depends on 1)

The polymer of claim 1, further comprising recurring units of at least one type selected from the general formulae (7), (8), and (9):
wherein
R1 is hydrogen, fluorine, methyl or trifluoromethyl,
X is an acid labile group, and
G is an oxygen atom or carbonyloxy (—C(═O)O—) group.

### Claim 4 (depends on 1)

A positive resist composition comprising the polymer of claim 1 as a base resin.

### Claim 5 (depends on 1)

A positive resist composition comprising the polymer of claim 1 and a polymer other than the polymer comprising recurring units having formulae (1a), (2) and (3) in claim 1 as a base resin.

### Claim 6 (depends on 4)

The positive resist composition of claim 4, further comprising a surfactant which is insoluble in water and soluble in an alkaline developer.

### Claim 7 (depends on 4)

A process for forming a pattern, comprising the steps of coating the positive resist composition of claim 4 onto a substrate and heat treating to form a resist film, exposing the resist film to high-energy radiation through a photomask, optionally heat treating, and developing the exposed resist film with a developer.

### Claim 8 (depends on 4)

A process for forming a pattern, comprising the steps of coating the positive resist composition of claim 4 onto a substrate and heat treating to form a resist film, coating onto the resist film a protective film which is insoluble in water and soluble in alkaline developer, exposing the resist film to high-energy radiation through a photomask with water held between the substrate and a projection lens, optionally heat treating, and developing the exposed resist film with a developer.

### Claim 9 (depends on 4)

A process for forming a pattern, comprising the steps of coating the positive resist composition of claim 4 onto a substrate and heat treating to form a resist film, imagewise writing with an electron beam, optionally heat treating, and developing the resist film with a developer.

### Claim 10 (depends on 4)

A process for forming a pattern, comprising the steps of coating the positive resist composition of claim 4 onto a substrate and heat treating to form a resist film, exposing the resist film to soft x-ray with a wavelength of 3 to 15 nm, optionally heat treating, and developing the resist film with a developer.

### Claim 11 (depends on 1)

The polymer of claim 1, having a weight average molecular weight of 3000 to 100,000.

### Claim 12 (depends on 1)

The polymer of claim 1, comprising:
from 1 to 30 mol % of constituent units of one or more type(s) having formula (1a);
from 10 to 50 mol % of constituent units of one or more type(s) having formula (2); and
from 10 to 50 mol % of constituent units of one or more type(s) having formula (3).

### Claim 13 (depends on 2)

The polymer of claim 2, comprising:
from 1 to 50 mol % of constituent units of one or more type(s) having formulae (4) to (6).

### Claim 14 (depends on 3)

The polymer of claim 3, comprising:
from 1 to 50 mol % of constituent units of one or more type(s) having formulae (7) to (9).

### Claim 15 (depends on 5)

The positive resist composition of claim 5, wherein said polymer other than the polymer comprising recurring units having formulae (1a), (2), and (3)
has a dissolution rate in alkaline developer which increases under the action of an acid and
is selected from the group consisting of
(i) poly(meth)acrylic acid derivatives,
(ii) norbornene derivative/maleic anhydride copolymers,
(iii) hydrogenated products of ring-opening metathesis polymerization polymers,
(iv) vinyl ether/maleic anhydride/(meth)acrylic acid derivative copolymers, and
(v) polyhydroxystyrene derivatives.

### Claim 16 (depends on 1)

The polymer of claim 1, wherein the recurring units having the general formula (1a) are at least one selected from the group consisting of recurring units having the following formulae: