Sulfonium compound, resist composition, and patterning process

Patent metadata

Field	Value
Publication number	US-11215926-B2
Application number	US-201816108645-A
Country	US
Kind code	B2
Filing date	Aug 22, 2018
Priority date	Aug 24, 2017
Publication date	Jan 4, 2022
Grant date	Jan 4, 2022

Abstract

A resist composition comprising a sulfonium compound of specific structure as PAG has excellent lithography performance factors such as minimal defects, high sensitivity, improved LWR and CDU, and is a quite effective resist material for precise micropatterning.

First claim

The invention claimed is:

1. A sulfonium compound having the formula (1):
Z—X-L 1 -SO 3 −   (1)

wherein L 1 is a straight, branched or cyclic C 1 -C 20 divalent hydrocarbon group which may contain a heteroatom-containing moiety, X is an ether bond, and Z is a group of sulfonium cation structure having the formula (1A), (1B) or (1C):

wherein the broken line denotes a valence bond to X,
A is a single bond, methylene, carbonyl, sulfinyl, sulfonyl, amino, ether bond, thioether bond, ester bond, carbonate bond, carbamate bond or sulfonic acid ester bond,
R 1a to R 1c are each independently a straight, branched or cyclic C 1 -C 20 monovalent hydrocarbon group which may contain a heteroatom-containing moiety, at least one of R 1a to R 1c being a group of the formula (1-1) shown below, with the proviso that where at least two R 1a are included, two of them may bond together to form a ring with carbon atoms on the benzene ring to which they are attached, where at least two R 1b are included, two of them may bond together to form a ring with carbon atoms on the benzene ring to which they are attached, and where at least two R 1c are included, two of them may bond together to form a ring with carbon atoms on the benzene ring to which they are attached,
m1, m2 and m3 are integers in the range: 0≤m1≤5, 0≤m2≤5, 0≤m3≤4, and m1+m2+m3≥1,
n1, n2 and n3 are integers in the range: 0≤n1≤4, 0≤n2≤4, 0≤n3≤4, and n1+n2+n3≥1,
k1, k2 and k3 are integers in the range: 0≤k1≤5, 0≤k2≤4, 0≤k3≤3, and k1+k2+k3≥1,

wherein L 2 is a straight, branched or cyclic C 1 -C 20 divalent hydrocarbon group which may contain a heteroatom-containing moiety, R f1 and R f2 are each independently hydrogen, a straight, branched or cyclic C 1 -C 20 alkyl, fluorine, or straight, branched or cyclic C 1 -C 20 fluoroalkyl having at least one fluorine atom, at least one of R f1 and R f2 being fluorine or fluoroalkyl, the broken line denotes a valence bond.

2. The sulfonium compound of claim 1 wherein R f1 and R f2 are trifluoromethyl.

3. The sulfonium compound of claim 1 which has the formula (2):

wherein X and Z are as defined above, R f3 , R f4 , R f5 and R f6 are each independently hydrogen, fluorine or trifluoromethyl.

4. The sulfonium compound of claim 3 wherein both R f5 and R f6 are fluorine.

5. A photoacid generator comprising the sulfonium compound of claim 1 .

6. A resist composition comprising the photoacid generator of claim 5 .

7. The resist composition of claim 6 , further comprising a base resin containing a polymer comprising recurring units having the formula (a) and recurring units having the formula (b):

wherein R A is hydrogen, fluorine, methyl or trifluoromethyl, Z A is a single bond, phenylene group, naphthylene group or (backbone)-C(═O)—O—Z′—, Z′ is a straight, branched or cyclic C 1 -C 10 alkylene group which may contain a hydroxyl moiety, ether bond, ester bond or lactone ring, or phenylene group or naphthylene group, X A is an acid labile group, and Y A 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, sulfonic acid ester bond, carbonate bond, lactone ring, sultone ring and carboxylic anhydride.

8. The resist composition of claim 6 , further comprising an organic solvent.

9. The resist composition of claim 6 , further comprising a photoacid generator other than the photoacid generator comprising the sulfonium compound of formula (I).

10. The resist composition of claim 9 wherein the other photoacid generator has the formula (4) or (5):

wherein R 101 , R 102 , and R 103 are each independently straight, branched or cyclic C 1 -C 20 monovalent hydrocarbon group which may contain a heteroatom, any two of R 101 , R 102 and R 103 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 R fa , R fb1 , R fb2 , R fc1 , R fc2 and R fc3 are each independently fluorine or a straight, branched or cyclic C 1 -C 40 monovalent hydrocarbon group which may contain a heteroatom, or a pair of R fb1 and R fb2 , or R fc1 and R fc2 may bond together to form a ring with the carbon atom to which they are attached and any intervening atoms, R fd is a straight, branched or cyclic C 1 -C 40 monovalent hydrocarbon group which may contain a heteroatom,

wherein R 121 , R 122 and R 123 are each independently a straight, branched or cyclic C 1 -C 20 alkyl group, L is a single bond, ether bond, or a straight, branched or cyclic C 1 -C 20 divalent hydrocarbon group which may contain a heteroatom, X 1 , X 2 , X 3 and X 4 are each independently hydrogen, fluorine or trifluoromethyl, at least one of X 1 , X 2 , X 3 and X 4 is fluorine or trifluoromethyl, p1 and p2 are each independently an integer of 0 to 5, and p3 is an integer of 0 to 4.

11. The resist composition of claim 6 , further comprising an onium salt having the formula (6) or (7):
R 151 —SO 3 − M +   (6)

R 152 —CO 2 − M +   (7)

wherein R 151 and R 152 are each independently hydrogen or a straight, branched or cyclic C 1 -C 40 monovalent hydrocarbon group which may contain a heteroatom, exclusive of hydrocarbon groups in which the hydrogen atom in bond with the carbon atom at α-position relative to the sulfo group is replaced by a fluorine atom or fluoroalkyl moiety, and
M + is an onium cation.

12. The resist composition of claim 6 , further comprising an amine compound.

13. The resist composition of claim 6 , 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.

14. A pattern forming process comprising the steps of applying the resist composition of claim 6 onto a substrate, prebaking to form a resist film, exposing a selected region of the resist film to KrF excimer laser, ArF excimer laser, EB or EUV, baking, and developing the exposed resist film in a developer.

15. The pattern forming process of claim 14 wherein the developing step uses an alkaline aqueous solution as the developer, thereby forming a positive pattern in which an exposed region of the resist film is dissolved away and an unexposed region of the resist film is not dissolved.

16. The pattern forming process of claim 14 wherein the developing step uses an organic solvent as the developer, thereby forming a negative pattern in which an unexposed region of the resist film is dissolved away and an exposed region of the resist film is not dissolved.

17. The pattern forming process of claim 16 wherein the organic solvent is at least one solvent selected from the group consisting of 2-octanone, 2-nonanone, 2-

Assignees

• Shinetsu Chemical Co

Inventors

• Fujiwara Takayuki
• Mitsui Ryo
• Ohashi Masaki
• Taniguchi Ryosuke
• Hasegawa Koji

Classifications

• C07D339/08

  Six-membered rings · CPC title

• G03F7/20

  Exposure; Apparatus therefor (photographic printing apparatus for making copies G03B27/00) · CPC title

• C07D327/08

  [b,e]-condensed with two six-membered carbocyclic rings · CPC title

• G03F7/322

  Aqueous alkaline compositions · CPC title

• C07C2601/14

  The ring being saturated · CPC title