Resist composition and patterning process

1. A resist composition comprising (A) a compound, (B) a resin adapted to change its solubility in an organic solvent base developer under the action of acid, and (C) a photoacid generator,

wherein the compound (A) is selected from the group consisting of the following formulae:

the resin (B) comprising recurring units having the formula (2) and recurring units having the formula (3):

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

2. The resist composition of claim 1 wherein the photoacid generator (C) has the formula (4) or (5):

M + X −   (4)

wherein M + is a sulfonium cation of the formula (4a) or iodonium cation of the formula (4b):

wherein R 100 , R 200 and R 300 are each independently a straight, branched or cyclic C 1 -C 20 monovalent hydrocarbon group which may contain a heteroatom, any two or more of R 100 , R 200 and R 300 may bond together to form a ring with the sulfur atom to which they are attached, R 400 and R 500 are each independently a straight, branched or cyclic C 1 -C 20 monovalent hydrocarbon group which may contain a heteroatom, and

X − is an anion selected from the formulae (4c) to (4f):

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 600 and R 700 are each independently a straight, branched or cyclic C 1 -C 20 monovalent hydrocarbon group which may contain a heteroatom, R 800 is a straight, branched or cyclic C 1 -C 20 divalent hydrocarbon group which may contain a heteroatom, any two or more of R 600 , R 700 and R 800 may bond together to form a ring with the sulfur atom to which they are attached, L is a single bond or linking group, X 1 and X 2 are each independently fluorine or trifluoromethyl, X 3 and X 4 are each independently hydrogen, fluorine or trifluoromethyl, and k is an integer of 0 to 3.

3. The resist composition of claim 1 , further comprising (D) an organic solvent.

4. The resist composition of claim 1 , further comprising (E) a hydrophobic fluoro-resin.

5. The resist composition of claim 1 , further comprising (F) at least one compound selected from the formulae (6a), (6b) and (6c):

wherein Mq + is a sulfonium cation of the formula (4a), iodonium cation of the formula (4b), or ammonium cation, R B is a straight, branched or cyclic C 1 -C 40 monovalent hydrocarbon group which may contain a heteroatom, X B1 , X B2 , X B3 and X B4 are each independently hydrogen or a straight, branched or cyclic C 1 -C 40 monovalent hydrocarbon group which may contain a heteroatom, exclusive of trifluoromethyl, Lq is a single bond or linking group, and Ar is an optionally substituted aromatic ring,

wherein R 100 , R 200 and R 300 are each independently a straight, branched or cyclic C 1 -C 20 monovalent hydrocarbon group which may contain a heteroatom, any two or more of R 100 , R 200 and R 300 may bond together to form a ring with the sulfur atom to which they are attached, R 400 and R 500 are each independently a straight, branched or cyclic C 1 -C 20 monovalent hydrocarbon group which may contain a heteroatom.

6. The resist composition of claim 1 , further comprising at least one basic compound selected from the group consisting of primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds with carboxyl group, nitrogen-containing compounds with sulfonyl group, nitrogen-containing compounds with hydroxyl group, nitrogen-containing compounds with hydroxyphenyl group, alcoholic nitrogen-containing compounds, amide derivatives, and imide derivatives.

7. A process for forming a pattern, comprising the steps of coating the resist composition of claim 1 onto a substrate, prebaking the coating to form a resist film, exposing the resist film to ArF excimer laser, EB or EUV, baking, and developing the resist film in a developer.

8. The process of claim 7 wherein the exposure step is performed by immersion lithography while keeping a liquid having a refractive index of at least 1.0 between the resist film and a projection lens.

9. The process of claim 8 , further comprising the step of coating a protective film on the resist film, wherein the liquid is kept between the protective film and the projection lens.

10. The process of claim 7 , wherein the developer comprises an organic solvent and the development step is to form a negative pattern.

11. The process of claim 10 wherein the organic solvent is at least one solvent selected from the group consisting of

2-octanone, 3-octanone, 4-octanone, 2-nonanone, 3-nonanone,

4-nonanone, 5-nonanone, 2-heptanone, 3-heptanone, 4-heptanone,

2-hexanone, 3-hexanone, diisobutyl ketone,

2-methylcyclohexanone, 3-methylcyclohexanone,

4-methylcyclohexanone, 2-ethylcyclohexanone,

3-ethylcyclohexanone, 4-ethylcyclohexanone, acetophenone,

2′-methylacetophenone, 4′-methylacetophenone,

2′-ethylacetophenone, 4′-ethylacetophenone,

ethyl n-butyl ketone, di-n-butyl ketone, propyl acetate,

butyl acetate, isobutyl acetate, pentyl acetate,

isopentyl acetate, butenyl acetate, phenyl acetate,

propyl formate, butyl formate, isobutyl formate,

pentyl formate, isopentyl formate, methyl valerate,

methyl pentenoate, methyl crotonate, ethyl crotonate,

methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate,

methyl lactate, ethyl lactate, propyl lactate, butyl lactate,

isobutyl lactate, pentyl lactate, isopentyl lactate,

methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate,

methyl benzoate, ethyl benzoate, benzyl acetate,

methyl phenylacetate, benzyl formate, phenylethyl formate,

methyl 3-phenylpropionate, benzyl propionate,

ethyl phenylacetate, 2-phenylethyl acetate,

2-methylbutyl acetate, hexyl acetate, 2-ethylhexyl acetate,

cyclohexyl acetate, methylcyclohexyl acetate, hexyl formate,

ethyl valerate, propyl valerate, isopropyl valerate,

butyl valerate, isobutyl valerate, t-butyl valerate,

pentyl valerate, isopentyl valerate, ethyl isovalerate,

propyl isovalerate, isopropyl isovalerate, butyl isovalerate,

isobutyl isovalerate, t-butyl isovalerate,

isopentyl isovalerate, ethyl 2-methylvalerate,

butyl 2-methylvalerate, ethyl pivalate, propyl pivalate,

isopropyl pivalate, butyl pivalate, t-butyl pivalate,

ethyl pentenoate, propyl pentenoate, isopropyl pentenoate,

butyl pentenoate, t-butyl pentenoate, propyl crotonate,

isopropyl crotonate, butyl crotonate, t-butyl crotonate,

butyl propionate, isobutyl propionate, t-butyl propionate,

ethyl hexanoate, allyl hexanoate, propyl butyrate,

butyl butyrate, isobutyl butyrate, 3-methylbutyl butyrate,

t-butyl butyrate, ethyl 2-methylbutyrate,

isopropyl 2-methylbutyrate, propyl benzoate, butyl benzoate,

1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol,

t-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol,

t-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol,

3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol,

1-hexanol, 2-hexanol, 3-hexanol, 2,3-dimethyl-2-butanol,

3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol,

2,2-diethyl-1-butanol, 2-methyl-1-pentanol,

2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol,

3-methyl-2-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol,

4-methyl-3-pentanol, cyclohexanol, and 1-octanol.

12. A resist composition comprising (A) a compound, (B) a resin adapted to change its solubility in an organic solvent base developer under the action of acid, and (C) a photoacid generator,

the compound (A) having the formula (1):

wherein R 1 to R 4 are each independently hydrogen, hydroxyl, or a straight, branched or cyclic C 1 -C 20 monovalent hydrocarbon group which may contain a heteroatom, and R 2 and R 3 are not hydrogen at the same time,

the resin (B) comprising recurring units having the formula (2) and recurring units having the formula (3):

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