Chemically amplified resist composition and patterning process

1. A chemically amplified resist composition comprising a quencher and an acid generator,

said quencher comprising a salt compound consisting of a nitrogen-containing cation and a 1,1,1,3,3,3-hexafluoro-2-propoxide anion having bonded thereto a group selected from trifluoromethyl, hydrocarbylcarbonyl and hydrocarbyloxycarbonyl.

2. The resist composition of claim 1 wherein the salt compound has the formula (1) or (2):

wherein m is an integer of 1 to 4, n is an integer of 0 to 4,

R 1 is a trifluoromethyl, C 2 -C 21 hydrocarbylcarbonyl or C 2 -C 21 hydrocarbyloxycarbonyl group, the hydrocarbyl moiety in the hydrocarbylcarbonyl or hydrocarbyloxycarbonyl group may contain at least one moiety selected from ether bond, ester bond, thiol, cyano, nitro, hydroxy, sultone, sulfonate bond, amide bond and halogen,

R 2 to R 13 are each independently hydrogen or a C 1 -C 24 hydrocarbyl group which may contain a halogen atom, hydroxy, carboxy, ether bond, ester bond, thioether bond, thioester bond, thionoester bond, dithioester bond, amino, nitro, cyano, sulfone or ferrocenyl moiety, at least two of R 2 to R 5 or at least two of R 6 to R 13 may bond together to form a ring with the nitrogen atom to which they are attached or the nitrogen atom to which they are attached and an intervening atom, R 2 and R 3 may bond together to form ═C(R 2A (R 3A ), R 2A and R 3A are each independently hydrogen or a C 1 -C 16 hydrocarbyl group which may contain oxygen, sulfur or nitrogen, R 2A and R 4 may bond together to form a ring with the carbon and nitrogen atoms to which they are attached, the ring may contain a double bond, oxygen, sulfur or nitrogen,

R 14 is a C 1 -C 12 (m+1)-valent saturated hydrocarbon group when n is 0, and a C 2 -C 12 saturated hydrocarbylene group when n is an integer of 1 to 4, the hydrocarbon and hydrocarbylene groups may contain an ether bond, ester bond, carboxy moiety, thioester bond, thionoester bond or dithioester bond,

R 15 is a C 2 -C 12 saturated hydrocarbylene group which may contain an ether bond, ester bond, carboxy moiety, thioester bond, thionoester bond or dithioester bond.

3. The resist composition of claim 1 wherein the acid generator generates a sulfonic acid, imide acid or methide acid.

4. The resist composition of claim 1 , further comprising a base polymer.

5. The resist composition of claim 4 wherein the base polymer comprises repeat units having the formula (a1) or repeat units having the formula (a2):

wherein R A is each independently hydrogen or methyl, R 21 and R 22 are each independently an acid labile group, X 1 is a single bond, phenylene, naphthylene, or a C 1 -C 12 linking group containing an ester bond and/or lactone ring, and X 2 is a single bond or ester bond.

6. The resist composition of claim 5 which is a chemically amplified positive resist composition.

7. The resist composition of claim 4 wherein the base polymer is free of an acid labile group.

8. The resist composition of claim 7 which is a chemically amplified negative resist composition.

9. The resist composition of claim 4 wherein the base polymer comprises repeat units of at least one type selected from repeat units having the formulae (f1) to (f3):

wherein R A is each independently hydrogen or methyl,

Z 1 is a single bond, a C 1 -C 6 aliphatic hydrocarbylene group, phenylene group, naphthylene group, or C 7 -C 18 group obtained by combining the foregoing, or —O—Z 11 —, —C(═O)—O—Z 11 — or —C(═O)—NH—Z 11 —, Z 11 is a C 1 -C 6 aliphatic hydrocarbylene group, phenylene group, naphthylene group, or C 7 -C 18 group obtained by combining the foregoing, which may contain a carbonyl moiety, ester bond, ether bond or hydroxy moiety,

Z 2 is a single bond, —Z 21 —C(═O)—O—, —Z 21 —O— or —Z 21 —O—C(═O)—, Z 21 is a C 1 -C 12 saturated hydrocarbylene group which may contain a carbonyl moiety, ester bond or ether bond,

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 aliphatic hydrocarbylene group, phenylene group, fluorinated phenylene group, or trifluoromethyl-substituted phenylene group, which may contain a carbonyl moiety, ester bond, ether bond or hydroxy moiety,

R 31 to R 38 are each independently halogen or a C 1 -C 20 hydrocarbyl group which may contain a heteroatom, a pair of R 33 and R 34 or R 36 and R 37 may bond together to form a ring with the sulfur atom to which they an attached,

R HF is hydrogen or trifluoromethyl, and

M − is a non-nucleophilic counter ion.

10. The resist composition of claim 1 , further comprising an organic solvent.

11. The resist composition of claim 1 , further comprising a surfactant.

12. A pattern forming process comprising the steps of applying the chemically amplified resist composition of claim 1 to form a resist film on a substrate, exposing the resist film to high-energy radiation, and developing the exposed resist film in a developer.

13. The process of claim 12 wherein the high-energy radiation is i-line of wavelength 365 nm, ArF excimer laser of wavelength 193 nm or KrF excimer laser of wavelength 248 nm.

14. The process of claim 12 wherein the high-energy radiation is EB or EUV of wavelength 3 to 15 nm.