Resist composition and patterning process

1. A resist composition comprising a base polymer and a 2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane, biguanide or phosphazene salt of an iodinated aromatic group-containing carboxylic acid.

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

wherein R 1 is hydrogen, hydroxyl, a C 1 -C 6 straight, branched or cyclic alkyl group, C 1 -C 6 straight, branched or cyclic alkoxy group, C 2 -C 6 straight, branched or cyclic acyloxy group, fluorine, chlorine, bromine, amino, —NR 2 —C(═O)—R 3 , or —NR 2 —C(═O)—O—R 3 , R 2 is hydrogen or a C 1 -C 6 straight, branched or cyclic alkyl group, R 3 is a C 1 -C 6 straight, branched or cyclic alkyl group or C 2 -C 8 straight, branched or cyclic alkenyl group, G is a single bond or a C 1 -C 20 (p+1)-valent linking group which may contain an ether, carbonyl, ester, amide, sultone, lactam, carbonate, halogen, hydroxyl or carboxyl moiety, p is an integer of 1 to 3, m is an integer of 1 to 5, n is an integer of 0 to 3,

A + is a cation having the formula (A)-1, (A)-2 or (A)-3:

wherein R 11 to R 13 are each independently hydrogen, a C 1 -C 24 straight, branched or cyclic alkyl group, C 2 -C 24 straight, branched or cyclic alkenyl group, C 2 -C 24 straight, branched or cyclic alkynyl group, or C 6 -C 20 aryl group,

R 14 to R 21 are each independently hydrogen, or a C 1 -C 24 straight, branched or cyclic alkyl group, C 2 -C 24 straight, branched or cyclic alkenyl group, C 2 -C 24 straight, branched or cyclic alkynyl group, or C 6 -C 20 aryl group, which may contain an ester, ether, sulfide, sulfoxide, carbonate, carbamate, sulfone, halogen, amino, amide, hydroxyl, thiol, or nitro moiety, or a pair of R 14 and R 15 , R 15 and R 16 , R 16 and R 17 , R 17 and R 18 , R 19 and R 19 , R 19 and R 20 , or R 20 and R 21 may bond together to form a ring which may contain an ether moiety,

R 22 to R 29 are each independently hydrogen, or a C 1 -C 24 straight, branched or cyclic alkyl group, C 2 -C 24 straight, branched or cyclic alkenyl group, C 2 -C 24 straight, branched or cyclic alkynyl group, or C 6 -C 20 aryl group, which may contain an ester, ether, sulfide, sulfoxide, carbonate, carbamate, sulfone, halogen, amino, amide, hydroxyl, thiol, or nitro moiety, or a pair of R 22 and R 23 , R 23 and R 24 , R 24 and R 25 , R 25 and R 26 , R 26 and R 27 , or R 27 and R 28 may bond together to form a ring or R 23 and R 24 , R 25 and R 26 , R 27 and R 28 , or R 28 and R 29 , taken together, may form a group having the formula (A)-3-1, or when R 22 is hydrogen, R 23 may be a group having the formula (A)-3-2:

wherein R 30 to R 39 are each independently hydrogen, or a C 1 -C 24 straight, branched or cyclic alkyl group, C 2 -C 24 straight, branched or cyclic alkenyl group, C 2 -C 24 straight, branched or cyclic alkynyl group, or C 6 -C 20 aryl group, or a pair of R 30 and R 31 , R 31 and R 32 , R 32 and R 33 , R 33 and R 34 , R 34 and R 35 , R 36 and R 37 , or R 38 and R 39 may bond together to form a ring, or R 30 and R 31 , R 32 and R 33 , or R 34 and R 35 , taken together, may form a group having the formula (A)-3-1.

3. The resist composition of claim 1 , further comprising an acid generator capable of generating sulfonic acid, sulfonimide or sulfonmethide.

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

5. The resist composition of claim 1 wherein the base polymer comprises recurring units having the formula (a1) or recurring units having the formula (a2):

wherein R A is each independently hydrogen or methyl, R 41 and R 42 are each independently an acid labile group, X is a single bond, phenylene, naphthylene, or a C 1 -C 12 linking group containing ester moiety or lactone ring, and Y is a single bond or ester group.

6. The resist composition of claim 5 , further comprising a dissolution inhibitor.

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

8. The resist composition of claim 1 wherein the base polymer is an acid labile group-free polymer.

9. The resist composition of claim 8 , further comprising a crosslinker.

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

11. The resist composition of claim 1 wherein the base polymer further comprises recurring units of at least one type selected from recurring units having the formulae (f1) to (f3):

wherein R A is each independently hydrogen or methyl,

Z 1 is a single bond, phenylene, —O—Z 11 —, or —C(═O)—Z 12 —Z 11 —, Z 11 is a straight, branched or cyclic C 1 -C 6 alkylene group or straight, branched or cyclic C 2 -C 6 alkenylene group which may contain a carbonyl, ester, ether or hydroxyl moiety, or phenylene group, Z 12 is —O— or —NH—,

R 51 , R 52 , R 53 , R 54 , R 55 , R 56 , R 57 , and R 58 are each independently a straight, branched or cyclic C 1 -C 12 alkyl group which may contain a carbonyl, ester or ether moiety, or a C 6 -C 12 aryl, C 7 -C 20 aralkyl, or mercaptophenyl group,

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

Z 3 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, —O—Z 31 —, or —C(═O)—Z 32 —Z 31 —, Z 31 is a straight, branched or cyclic C 1 -C 6 alkylene group or straight, branched or cyclic C 2 -C 6 alkenylene group which may contain a carbonyl, ester, ether or hydroxyl moiety, or a phenylene, fluorinated phenylene or trifluoromethyl-substituted phenylene group, Z 32 is —O— or —NH—,

A 1 is hydrogen or trifluoromethyl, and M − is a non-nucleophilic counter ion.

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

13. A pattern forming process comprising the steps of coating the resist composition of claim 1 onto a substrate, baking, exposing the resulting resist film to high-energy radiation, and developing with a developer.

14. The process of claim 13 wherein the high-energy radiation is ArF excimer laser of wavelength 193 nm or KrF excimer laser of wavelength 248 nm.

15. The process of claim 13 wherein the high-energy radiation is EB or EUV of wavelength 3 to 15 nm.