Onium salt, chemically amplified positive resist composition, and resist pattern forming process

Patent metadata

Field	Value
Publication number	US-11036136-B2
Application number	US-201916420680-A
Country	US
Kind code	B2
Filing date	May 23, 2019
Priority date	May 25, 2018
Publication date	Jun 15, 2021
Grant date	Jun 15, 2021

Abstract

An onium salt of arenesulfonic acid having a bridged ring-containing group generates a bulky acid having an appropriate strength and controlled diffusion. When a positive resist composition comprising the onium salt and a base polymer is processed by lithography, a pattern of rectangular profile having high resolution and reduced LER is formed.

First claim

The invention claimed is:

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

wherein X 1 and X 2 are each independently methylene, propane-2,2-diyl or ether bond,
L is a single bond, ester bond, sulfonic acid ester bond, carbonate bond or carbamate bond,
R 1 and R 2 are each independently a C 1 -C 20 monovalent hydrocarbon group which may contain a heteroatom,
m 1 and m 2 are each independently an integer of 0 to 2, m 3 is 0 or 1, n 1 is an integer satisfying 1≤n 1 ≤5+2m 1 , n 2 is an integer satisfying 0≤n 2 ≤4+2m 2 , n 3 is an integer satisfying 0≤n 3 ≤8+4m 3 ,
A + is a sulfonium cation having the formula (2), an iodonium cation having the formula (3), or an ammonium cation having the formula (4):

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

2. A chemically amplified positive resist composition comprising (A) an acid generator containing the onium salt of claim 1 and (B) a base polymer containing a polymer adapted to be decomposed under the action of acid to increase its solubility in alkaline developer.

3. The resist composition of claim 2 wherein the polymer comprises 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 1 is an integer satisfying 0≤a 1 ≤5+2x 1 −a 2 , and a 2 is an integer of 1 to 3.

4. The resist composition of claim 2 wherein the polymer comprises recurring units having the formula (B2):

wherein R A is hydrogen, fluorine, methyl or trifluoromethyl,
R 12 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 2 is a single bond or C 1 -C 10 alkanediyl group in which an ether bond may intervene in a carbon-carbon bond,
t 2 is 0 or 1, x 2 is an integer of 0 to 2, b 1 is an integer satisfying 0≤b 1 ≤5+2x 2 −b 3 , b 2 is 0 or 1, b 3 is an integer of 1 to 3, X is an acid labile group in case of b 3 =1, and X is each independently hydrogen or an acid labile group in case of b 3 =2 or 3, at least one X being an acid labile group.

5. The resist composition of claim 2 wherein the polymer comprises recurring units of at least one type selected from units having the formulae (B3), (B4), and (B5):

wherein R A is hydrogen, fluorine, methyl or trifluoromethyl,
R 13 and R 14 are each independently a hydroxyl group, halogen atom, acetoxy group, optionally halogenated C 1 -C 6 alkyl group, optionally halogenated C 1 -C 6 primary alkoxy group, optionally halogenated C 2 -C 6 secondary alkoxy group, optionally halogenated C 2 -C 8 acyloxy group, or optionally halogenated C 2 -C 8 alkylcarbonyloxy group,
R 15 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 3 is a single bond or C 1 -C 10 alkanediyl group in which an ether bond may intervene in a carbon-carbon bond,
c is an integer of 0 to 6, d is an integer of 0 to 4, e is an integer of 0 to 5, t 3 is 0 or 1, and x 3 is an integer of 0 to 2.

6. The resist composition of claim 2 wherein the polymer further comprises recurring units of at least one type selected from units having the formulae (B6) to (B11):

wherein R A is hydrogen, fluorine, methyl or trifluoromethyl,
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, 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 each independently 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, ester bond, ether bond or hydroxyl moiety,
R 21 to R 33 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 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 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.

7. The resist composition of claim 2 , further comprising (C) an organic solvent.

8. The resist composition of claim 2 , further comprising (D) a fluorinated polymer comprising recurring units having the formula (D) and recurring units of at least one type selected from units having the formulae (D2), (D3), (D4), and (D5):

wherein R B is hydrogen or methyl,
R C is each independently hydrogen, fluorine, methyl or trifluoromethyl,
R 51 is hydrogen or a C 1 -C 5 straight or branched monovalent hydrocarbon group in which a heteroatom-containing moiety may intervene in a carbon-carbon bond,
R 52 is a C 1 -C 5 straight or branched monovalent hydrocarbon group in which a heteroatom-containing moiety may intervene in a carbon-carbon bond,
R 53a , R 53b , R 55a and R 55b are each independently hydrogen or a C 1 -C 10 alkyl group,
R 54 , R 56 , R 57 and R 58 are each independently hydrogen, a C 1 -C 15 monovalent hydrocarbon group, C 1 -C 15 monovalent fluorinated hydrocarbon group, or an acid labile group, with the proviso that an ether bond or carbonyl moiety may intervene in a carbon-carbon bond in the monovalent hydrocarbon groups or monovalent fluorinated hydrocarbon groups represented by R 54 , R 56 , R 57 and R 58 ,
Y 1 is a single bond, —C(═O)—O— or —C(═O)—NH—,
Y 2 is a C 1 -C 20 (h+1)-valent hydrocarbon group or C 1 -C 20 (h+1)-valent fluorinated hydrocarbon group,
g 1 is an integer of 1 to 3, g 2 is an integer satisfying 0≤g 2 ≤5+2g 3 −g 1 , g 3 is 0 or 1, and h is an integer of 1 to 3.

9. A resist pattern forming process comprising the steps of:
applying the resist composition of claim 2 onto a substrate to form a resist film thereon, exposing the resis

Assignees

• Shinetsu Chemical Co

Inventors

• Inoue Naoya
• Watanabe Satoshi
• Domon Daisuke

Classifications

• G03F7/0395 Primary

  the macromolecular compound having a backbone with alicyclic moieties · CPC title

• G03F7/0045 Primary

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

• C08F220/283

  and containing one or more carboxylic moiety in the chain, e.g. acetoacetoxyethyl(meth)acrylate · CPC title

• C08F220/382

  and containing oxygen, e.g. 2-sulfoethyl (meth)acrylate · CPC title

• C08F220/281

  and containing only one oxygen, e.g. furfuryl (meth)acrylate or 2-methoxyethyl (meth)acrylate · CPC title