Resist composition and patterning process

1. A resist composition comprising a base polymer and a metal salt of an iodinated aromatic group-containing carboxylic acid, the metal being selected from the group consisting of sodium, magnesium, potassium, calcium, rubidium, strontium, cesium, barium, cobalt, nickel, copper, zinc, cadmium, tin, antimony, zirconium, hafnium, cerium, aluminum, and indium,

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, q is an integer of 1 to 5, r is an integer of 0 to 3, M n+ is a metal ion selected from the group consisting of Na + , Mg 2+ , K + , Ca 2+ , Rb + , Sr 2+ , Cs + , Ba 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Sn 4+ , Sb 3+ , Zr 4+ , Hf 4+ , Ce 3+ , Al 3+ , and In 3+ , and n indicative of the valence number of M n+ is an integer of 1 to 4,

wherein the base polymer consists of recurring units having the formula (a1) or recurring units having the formula (a2), and recurring units of at least one type selected from recurring units having the formulae (f1) to (f3), and optionally at least one selected from the group consisting of

recurring units (b) having a phenolic hydroxyl group as an adhesive group,

recurring units (c) having an adhesive group selected from hydroxyl (other than phenolic hydroxyl), lactone ring, ether, ester and cyano groups,

recurring units (d) selected from units of indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, and norbornadiene, or derivatives thereof, and

recurring units (e) which are derived from styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methyleneindene, vinylpyridine, or vinylcarbazole:

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,

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 C 1 -C 6 straight, branched or cyclic alkylene group or C 2 -C 6 straight, branched or cyclic 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, R 56 , R 57 , and R 58 are each independently a C 1 -C 12 straight, branched or cyclic 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 C 1 -C 12 straight, branched or cyclic 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 C 1 -C 6 straight, branched or cyclic alkylene group or C 2 -C 6 straight, branched or cyclic 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.

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

3. The resist composition of claim 1 , further comprising a dissolution inhibitor.

4. The resist composition of claim 1 which is a chemically amplified positive resist composition.

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

6. 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.

7. The process of claim 6 wherein the high-energy radiation is ArF excimer laser of wavelength 193 nm or KrF excimer laser of wavelength 248 nm.

8. The process of claim 6 wherein the high-energy radiation is electron beam or extreme ultraviolet of wavelength 3 to 15 nm.

9. A resist composition comprising a base polymer, an acid generator capable of generating sulfonic acid, sulfonimide or sulfonmethide, and a metal salt of an iodinated aromatic group-containing carboxylic acid, the metal being selected from the group consisting of sodium, magnesium, potassium, calcium, rubidium, strontium, cesium, barium, cobalt, nickel, copper, zinc, cadmium, tin, antimony, zirconium, hafnium, cerium, aluminum, and indium,

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, q is an integer of 1 to 5, r is an integer of 0 to 3, M n+ is a metal ion selected from the group consisting of Na + , Mg 2+ , K + , Ca 2+ , Rb + , Sr 2+ , Cs + , Ba 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Sn 4+ , Sb 3+ , Zr 4+ , Hf 4+ , Ce 3+ , Al 3+ , and In 3+ , and n indicative of the valence number of M n+ is an integer of 1 to 4,

wherein the base polymer consists of recurring units having the formula (a1) or recurring units having the formula (a2), and optionally at least one selected from the group consisting of

recurring units (b) having a phenolic hydroxyl group as an adhesive group,

recurring units (c) having an adhesive group selected from hydroxyl (other than phenolic hydroxyl), lactone ring, ether, ester and cyano groups,

recurring units (d) selected from units of indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, and norbornadiene, or derivatives thereof, and

recurring units (e) which are derived from styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methyleneindene, vinylpyridine, or vinylcarbazole:

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.

10. A resist composition comprising a base polymer, an acid generator capable of generating sulfonic acid, sulfonimide or sulfonmethide, and a metal salt of an iodinated aromatic group-containing carboxylic acid, the metal being selected from the group consisting of sodium, magnesium, potassium, calcium, rubidium, strontium, cesium, barium, cobalt, nickel, copper, zinc, cadmium, tin, antimony, zirconium, hafnium, cerium, aluminum, and indium,

wherein the base polymer is an acid labile group-free polymer,

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, q is an integer of 1 to 5, r is an integer of 0 to 3, M n+ is a metal ion selected from the group consisting of Na + , Mg 2+ , K + , Ca 2+ , Rb + , Sr 2+ , Cs + , Ba 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Sn 4+ , Sb 3+ , Zr 4+ , Hf 4+ , Ce 3+ , Al 3+ , and In 3 , and n indicative of the valence number of M n+ is an integer of 1 to 4,

wherein the base polymer consists of at least one selected from the group consisting of:

recurring units (b) having a phenolic hydroxyl group as an adhesive group,

recurring units (c) having an adhesive group selected from hydroxyl (other than phenolic hydroxyl), lactone ring, ether, ester and cyano groups,

recurring units (d) selected from units of indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, and norbornadiene, or derivatives thereof, and

recurring units (e) which are derived from styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methyleneindene, vinylpyridine, or vinylcarbazole.

11. The resist composition of claim 10 , further comprising a crosslinker.

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

13. A resist composition comprising a base polymer and a metal salt of an iodinated aromatic group-containing carboxylic acid, the metal being selected from the group consisting of sodium, magnesium, potassium, calcium, rubidium, strontium, cesium, barium, cobalt, nickel, copper, zinc, cadmium, tin, antimony, zirconium, hafnium, cerium, aluminum, and indium,

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, q is an integer of 1 to 5, r is an integer of 0 to 3, M n+ is a metal ion selected from the group consisting of Na + , Mg 2+ , K + , Ca 2+ , Rb + , Sr 2+ , Cs + , Ba 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Sn 4+ , Sb 3+ , Zr 4+ , Hf 4+ , Ce 3+ , Al 3+ , and In 3+ , and n indicative of the valence number of M n+ is an integer of 1 to 4,

wherein the base polymer is an acid labile group-free polymer,

wherein the base polymer consists of recurring units of at least one type selected from recurring units having the formulae (f1) to (f3), and at least one selected from the group consisting of:

recurring units (b) having a phenolic hydroxyl group as an adhesive group,

recurring units (c) having an adhesive group selected from hydroxyl (other than phenolic hydroxyl), lactone ring, ether, ester and cyano groups,

recurring units (d) selected from units of indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, and norbornadiene, or derivatives thereof,

recurring units (e) which are derived from styrene, vinylnaphthalene, vinvlanthracene, and vinylpyrene, methyleneindene, vinylpyridine, or vinvlcarbazol,

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 C 1 -C 6 straight, branched or cyclic alkylene group or C 2 -C 6 straight, branched or cyclic 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, R 56 , R 57 , and R 58 are each independently a C 1 -C 12 straight, branched or cyclic 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 C 1 -C 12 straight, branched or cyclic 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 C 1 -C 6 straight, branched or cyclic alkylene group or C 2 -C 6 straight, branched or cyclic 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.