Onium salt compound, resist composition, and pattern forming process

Patent metadata

Field	Value
Publication number	US-9989847-B2
Application number	US-201514829832-A
Country	US
Kind code	B2
Filing date	Aug 19, 2015
Priority date	Aug 21, 2014
Publication date	Jun 5, 2018
Grant date	Jun 5, 2018

Abstract

Sulfonium and iodonium salts of nitrogen-containing carboxylic acids are novel. The onium salt functions as an acid diffusion controlling agent in a resist composition, enabling to form a pattern of good profile with high resolution, improved MEF, LWR and DOF.

First claim

The invention claimed is:

1. A resist composition comprising
(A) an onium salt compound,
(B) a polymer,
(C) a photoacid generator, and
(D) an organic solvent,
wherein the onium salt compound has the general formula (1):

wherein R 1 to R 4 are each independently hydrogen, -L-CO 2 − , or a straight C 1 -C 20 or branched or cyclic C 3 -C 20 monovalent hydrocarbon group which may be substituted with or separated by a heteroatom, or a pair of R 1 and R 2 , R 2 and R 3 , or R 3 and R 4 may bond together to form a ring with the carbon atoms to which they are attached, L is a single bond or a straight C 1 -C 20 or branched or cyclic C 3 -C 20 divalent hydrocarbon group which may be substituted with or separated by a heteroatom,
R 5 is hydrogen or a straight C 1 -C 20 or branched or cyclic C 3 -C 20 monovalent hydrocarbon group which may be substituted with or separated by a heteroatom,
Z + is a sulfonium cation of the general formula (a) or iodonium cation of the general formula (b):

wherein R 100 , R 200 and R 300 are each independently a straight C 1 -C 20 or branched or cyclic C 3 -C 20 monovalent hydrocarbon group which may be substituted with or separated by a heteroatom, or any two or more of R 100 , R 200 and R 300 may bond together to form a ring with the sulfur atom, R 400 and R 500 are each independently a straight C 1 -C 20 or branched or cyclic C 3 -C 20 monovalent hydrocarbon group which may be substituted with or separated by a heteroatom,
the partial moiety of the formula:

designates a cyclic structure of 2 to 5 carbon atoms separated by nitrogen, wherein a hydrogen atom attached to any carbon atom of the cyclic structure may be substituted by a straight C 1 -C 20 or branched or cyclic C 3 -C 20 monovalent hydrocarbon group or -L-CO 2 − , and any carbon atom of the cyclic structure may be replaced by a sulfur, oxygen or nitrogen atom,
with the proviso that at least one substituent -L-CO 2 − is included in formula (1), and
wherein said polymer comprises recurring units having the general formulae (2) and (3):

wherein R 1a is hydrogen, fluorine, methyl or trifluoromethyl, Z a is a single bond, phenylene, naphthylene or (backbone)-C(═O)—O—Z′—, Z′ is a straight C 1 -C 10 or branched or cyclic C 3 -C 10 alkylene group which may contain a hydroxyl radical, ether bond, ester bond or lactone ring, or phenylene or naphthylene group, XA is an acid labile group, and YL 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.

2. The resist composition of claim 1 wherein the anion moiety in formula (1) is selected from the following formulae (q1) to (q35):

3. The resist composition of claim 1 wherein the polymer further comprises recurring units (d1) or (d2) having the general formula:

wherein R 1a is as defined above, R 100 , R 200 and R 300 are each independently a straight C 1 -C 20 or branched or cyclic C 3 -C 20 monovalent hydrocarbon group which may be substituted with or separated by a heteroatom, or any two or more of R 100 , R 200 and R 300 may bond together to form a ring with the sulfur atom, R 400 and R 500 are each independently a straight C 1 -C 20 or branched or cyclic C 3 -C 20 monovalent hydrocarbon group which may be substituted with or separated by a heteroatom, L′ is a C 2 -C 5 alkylene group, R Y is a straight C 1 -C 20 or branched or cyclic C 3 -C 20 monovalent hydrocarbon group which may be substituted with or separated by a heteroatom, A is hydrogen or trifluoromethyl, L″ is a single bond or a straight C 1 -C 20 or branched or cyclic C 3 -C 20 divalent hydrocarbon group which may be substituted with or separated by a heteroatom, m is 0 or 1, n is 0 or 1, with the proviso that n is 0 when L″ is a single bond.

4. The resist composition of claim 1 wherein the photoacid generator has the general formula (4):

wherein R 100 , R 200 , and R 300 are as defined above, X − is an anion of any one of the general formulae (5) to (8):

wherein R fa , R fb1 , R fb2 , R fc1 , R fc2 , and R fc3 are each independently fluorine or a straight C 1 -C 40 or branched or cyclic C 3 -C 40 monovalent hydrocarbon group which may be substituted with or separated by a heteroatom, R fb1 and R fb2 , or R fc1 and R fc2 may bond together to form a ring with the carbon atoms to which they are attached, R fd is a straight C 1 -C 40 or branched or cyclic C 3 -C 40 monovalent hydrocarbon group which may be substituted with or separated by a heteroatom.

5. The resist composition of claim 1 , further comprising a nonionic nitrogen-containing compound.

6. The resist composition of claim 1 , further comprising 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.

7. A pattern forming process comprising the steps of applying the resist composition of claim 1 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.

8. The pattern forming process of claim 7 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.

9. The pattern forming process of claim 8 , 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 film and the projection lens.

Assignees

• Shinetsu Chemical Co

Inventors

• Ohashi Masaki
• Hatakeyama Jun
• Fukushima Masahiro

Classifications

• G03F7/0046

  with perfluoro compounds, e.g. for dry lithography (G03F7/0048 takes precedence) · CPC title

• G03F7/0045 Primary

  with organic non-macromolecular light-sensitive compounds not otherwise provided for, e.g. dissolution inhibitors · CPC title

• G03F7/2041

  in the presence of a fluid, e.g. immersion; using fluid cooling means · CPC title

• G03F7/2053

  using a laser (ablative removal B41C) · CPC title

• G03F7/38

  Treatment before imagewise removal, e.g. prebaking {(G03F7/265 takes precedence)} · CPC title