Onium salt, negative resist composition, and resist pattern forming process

Patent metadata

Field	Value
Publication number	US-11429023-B2
Application number	US-201916655571-A
Country	US
Kind code	B2
Filing date	Oct 17, 2019
Priority date	Oct 25, 2018
Publication date	Aug 30, 2022
Grant date	Aug 30, 2022

Abstract

A negative resist composition comprising an onium salt having formula (A) and a base polymer is provided. The resist composition exhibits a high resolution during pattern formation and forms a pattern with minimal LER.

First claim

The invention claimed is:

1. An onium salt having the formula (A):

wherein R 1 is a C 1 -C 20 monovalent hydrocarbon group which may contain a heteroatom,
the ring R is a group having the formula (A1),

wherein the broken line designates a valence bond, R 2 is each independently a C 1 -C 20 monovalent hydrocarbon group, at least one R 2 is bonded at the ortho-position relative to the carbon atom bonded to the sulfonyl group, n is an integer of 2 to 5,
Z + is a sulfonium cation having the formula (A2) or iodonium cation having the formula (A3):

wherein R 3 to R 7 are each independently a C 1 -C 20 monovalent hydrocarbon group which may contain a heteroatom, any two or more of R 3 , R 4 and R 5 may bond together to form a ring with the sulfur atom to which they are attached.

2. The onium salt of claim 1 wherein R 2 is a C 3 -C 20 branched or cyclic monovalent hydrocarbon group.

3. The onium salt of claim 1 wherein n is an integer of 3 to 5.

4. The onium salt of claim 1 wherein R 2 is a C 3 -C 20 cyclic monovalent hydrocarbon group.

5. The onium salt of claim 1 wherein the anion in the onium salt having formula (A) is selected from the group consisting of the following formulae:

6. A negative resist composition comprising (A) the onium salt of claim 1 , and (B) a base polymer containing a polymer comprising recurring units having the formula (B1):

wherein R A is hydrogen, fluorine, methyl or trifluoromethyl, R 11 is each independently halogen, an optionally halogenated C 2 -C 8 acyloxy group, optionally halogenated C 1 -C 6 alkyl group, or optionally halogenated C 1 -C 6 alkoxy group, A 1 is a single bond or C 1 -C 10 alkanediyl group in which an ether bond may intervene in a carbon-carbon bond, t 1 is 0 or 1, x 1 is an integer of 0 to 2, a is an integer satisfying 0≤5≤2x 1 −b, and b is an integer of 1 to 5.

7. The negative resist composition of claim 6 wherein the polymer further comprises recurring units of at least one type selected from recurring units having the formulae (B2), (B3) and (B4):

wherein R A is hydrogen, fluorine, methyl or trifluoromethyl,
R 12 and R 13 are each independently hydroxyl, halogen, acetoxy, an optionally halogenated C 1 -C 8 alkyl group, optionally halogenated C 1 -C 8 primary alkoxy group, C 2 -C 8 secondary alkoxy group, optionally halogenated C 2 -C 8 acyloxy group, or optionally halogenated C 2 -C 8 alkylcarbonyloxy group,
R 14 is an acetyl group, acetoxy group, C 1 -C 20 alkyl group, C 1 -C 20 primary alkoxy group, C 2 -C 20 secondary alkoxy group, C 2 -C 20 acyloxy group, C 2 -C 20 alkoxyalkyl group, C 2 -C 20 alkylthioalkyl group, halogen atom, nitro group, or cyano group,
A 2 is a single bond or C 1 -C 10 alkanediyl group in which an ether bond may intervene in a carbon-carbon bond,
c and d are each independently an integer of 0 to 4, e is an integer of 0 to 5, x 2 is an integer of 0 to 2, and t 2 is 0 or 1.

8. The negative resist composition of claim 6 wherein the polymer further comprises recurring units having the formula (B5):

wherein R A is hydrogen, fluorine, methyl or trifluoromethyl,
R 15 is each independently halogen, an optionally halogenated C 2 -C 8 acyloxy group, optionally halogenated C 1 -C 6 alkyl group, or optionally halogenated C 1 -C 6 alkoxy group,
A 3 is a single bond or C 1 -C 10 alkanediyl group in which an ether bond may intervene in a carbon-carbon bond,
W 1 is hydrogen, a C 1 -C 10 monovalent aliphatic hydrocarbon group in which an ether bond, carbonyl moiety or carbonyloxy moiety may intervene in a carbon-carbon bond, or an optionally substituted monovalent aromatic ring group,
Rx and Ry are each independently hydrogen, an optionally hydroxy or alkoxy-substituted C 1 -C 15 alkyl group or an optionally substituted monovalent aromatic ring group, with the proviso that both Rx and Ry are not hydrogen at the same time, Rx and Ry may bond together to form a ring with the carbon atom to which they are attached,
x 3 is an integer of 0 to 2, t 3 is 0 or 1, f is an integer satisfying 0≤f≤5+2x 3 −g, and g is an integer of 1 to 3.

9. The negative resist composition of claim 8 wherein the polymer further comprises recurring units of at least one type selected from recurring units having the formulae (B6), (B7) and (B8):

wherein R B is each independently hydrogen or methyl,
Z 1 is a single bond, phenylene group, —O—Z 11 —, —C(═O)—O—Z 11 —, or —C(═O)—NH—Z 11 —, Z 11 is a C 1 -C 6 alkanediyl, C 2 -C 6 alkenediyl or phenylene group, which may contain a carbonyl moiety, ester bond, ether bond or hydroxyl moiety,
Z 2 is a single bond or —Z 21 —C(═O)—O—, Z 21 is a C 1 -C 20 divalent hydrocarbon group which may contain a heteroatom,
Z 3 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, —O—Z 31 —, —C(═O)—O—Z 31 —, or —C(═O)—NH—Z 31 —, Z 31 is a C 1 -C 6 alkanediyl, C 2 -C 6 alkenediyl or phenylene group, which may contain a carbonyl moiety, ester bond, ether bond or hydroxyl moiety,
R 21 to R 28 are each independently a C 1 -C 20 monovalent hydrocarbon group which may contain a heteroatom, or R 21 and R 22 may bond together to form a ring with the sulfur atom to which they are attached, or any two or more of R 23 , R 24 and R 25 may bond together to form a ring with the sulfur atom to which they are attached, any two or more of R 26 , R 27 and R 28 may bond together to form a ring with the sulfur atom to which they are attached, and
M − is a non-nucleophilic counter ion.

10. The negative resist composition of claim 9 wherein the base polymer (B) further contains a polymer free of recurring units having the formula (B6), recurring units having the formula (B7), and recurring units having the formula (B8).

11. The negative resist composition of claim 8 , which is free of a crosslinker.

12. The negative resist composition of claim 6 wherein the polymer comprises recurring units having the formula (B1-1), recurring units having the formula (B5-1), and recurring units having the formula (B7):

wherein R A is each independently hydrogen, fluorine, methyl or trifluoromethyl,
R B is hydrogen or methyl,
W 1 is hydrogen, a C 1 -C 10 monovalent aliphatic hydrocarbon group in which an ether bond, carbonyl moiety or carbonyloxy moiety may intervene in a carbon-carbon bond, or an optionally substituted monovalent aromatic ring group,
Rx and Ry are each independently hydrogen, an optionally hydroxy or alkoxy-substituted C 1 -C 15 alkyl group or an optionally substituted monovalent aromatic ring group, with the proviso that both Rx and Ry are not hydrogen at the sa

Assignees

• Shinetsu Chemical Co

Inventors

• Domon Daisuke
• Inoue Naoya
• Ohashi Masaki
• Masunaga Keiichi
• Kotake Masaaki

Classifications

• G03F7/162

  Coating on a rotating support, e.g. using a whirler or a spinner · CPC title

• G03F7/0045 Primary

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

• C07C2601/14

  The ring being saturated · CPC title

• G03F7/38

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

• C07C309/31

  by alkyl groups containing at least three carbon atoms · CPC title