Sulfonium salt-containing polymer, resist composition, and patterning process
A polymer comprising recurring units having formulae (1), (2) and (3) is provided as well as a chemically amplified resist composition comprising the same. R 1 is H, F, CH 3 or CF 3 , Rf is H, F, CF 3 or C 2 F 5 , A is an optionally fluorine or oxygen-substituted divalent organic group, R 2 , R 3 and R 4 are alkyl, alkenyl, oxoalkyl, aryl, aralkyl or aryloxoalkyl, or may form a ring with the sulfur atom, N=0-2, R 8 is H or alkyl, B is a single bond or optionally oxygen-substituted divalent organic group, a=0-3, b=1-3, and X is an acid labile group. The polymer generates a strong sulfonic acid which provides for effective cleavage of acid labile groups in a chemically amplified resist composition.
1. A polymer comprising recurring units having the general formulae (1), (2) and (3):
wherein
R 1 is hydrogen, fluorine, methyl or trifluoromethyl,
Rf is each independently hydrogen, fluorine, trifluoromethyl or pentafluoroethyl, both Rf's are not hydrogen,
A is a divalent C 1 -C 10 organic group which may have fluorine or oxygen substituted thereon, provided that A is not —CH 2 —,
R 2 , R 3 and R 4 are each independently a substituted or unsubstituted straight or branched C 1 -C 10 alkyl, alkenyl or oxoalkyl group or a substituted or unsubstituted C 6 -C 18 aryl, aralkyl or aryloxoalkyl group, or at least two of R 2 , R 3 and R 4 may bond together to form a ring with the sulfur atom to which they are attached,
N is an integer of 0 to 2,
R 8 is hydrogen or C 1 -C 10 alkyl,
B is a single bond or a divalent C 1 -C 10 organic group which may have oxygen substituted thereon,
a is an integer of 0 to 3,
b is an integer of 1 to 3, and
X is an acid labile group.
2. The polymer of claim 1 comprising recurring units having the general formulae (1a), (2) and (3):
wherein R 1 is hydrogen, fluorine, methyl or trifluoromethyl, Rf is each independently hydrogen, fluorine, trifluoromethyl or pentafluoroethyl, both Rf's are not hydrogen, R 2 , R 3 and R 4 are each independently a substituted or unsubstituted, straight or branched C 1 -C 10 alkyl, alkenyl or oxoalkyl group or a substituted or unsubstituted C 6 -C 18 aryl, aralkyl or aryloxoalkyl group, or at least two of R 2 , R 3 and R 4 may bond together to form a ring with the sulfur atom to which they are attached, N is an integer of 0 to 2, R 8 is hydrogen or C 1 -C 10 alkyl, B is a single bond or a divalent C 1 -C 10 organic group which may have oxygen substituted thereon, a is an integer of 0 to 3, b is an integer of 1 to 3, and X is an acid labile group.
3. The polymer of claim 1 , further comprising recurring units of at least one type selected from the general formulae (4) to (6):
wherein R 1 is hydrogen, fluorine, methyl or trifluoromethyl, R 6 and R 7 are each independently hydrogen or hydroxyl, Y is a substituent group of lactone structure, and Z is hydrogen, C 1 -C 15 fluoroalkyl or C 1 -C 15 fluoroalcohol-containing substituent group.
4. The polymer of claim 1 , further comprising recurring units of at least one type selected from the general formulae (7) to (10):
wherein R 1 is hydrogen, fluorine, methyl or trifluoromethyl, X is an acid labile group, and G is an oxygen atom or carbonyloxy group (—C(═O)O—).
5. A positive resist composition comprising the polymer of claim 1 as a base resin.
6. The positive resist composition of claim 5 , further comprising a surfactant which is insoluble in water and soluble in an alkaline developer.
7. A pattern forming process comprising the steps of applying the positive resist composition of claim 5 onto a substrate to form a coating, heat treating the coating and exposing it to high-energy radiation through a photomask, optionally heat treating the exposed coating and developing it with a developer.
8. A pattern forming process comprising the steps of applying the positive resist composition of claim 5 onto a substrate to form a resist coating, heat treating the resist coating, applying onto the resist coating a protective coating which is insoluble in water and soluble in an alkaline developer, exposing the coated substrate to high-energy radiation from a projection lens through a photomask while holding water between the substrate and the projection lens, optionally heat treating the exposed coating and developing it with a developer.
9. A pattern forming process comprising the steps of applying the positive resist composition of claim 5 onto a substrate to form a coating, heat treating the coating, imagewise writing with an electron beam, optionally heat treating the coating, and developing it with a developer.
10. A positive resist composition comprising the polymer of claim 1 and a polymer which does not contain the recurring units of formula (1) in claim 1 as a base resin.
11. A pattern forming process comprising the steps of
applying a positive resist composition onto a substrate to form a coating,
exposing the coating to soft x-ray having a wavelength of 3 to 15 nm, and
optionally heat treating the exposed coating and developing it with a developer,
said resist composition comprising a polymer comprising recurring units having the general formulae (1′), (2) and (3):
wherein
R 1 is hydrogen, fluorine, methyl or trifluoromethyl,
Rf is each independently hydrogen, fluorine, trifluoromethyl or pentafluoroethyl, both Rf's are not hydrogen,
A′ is a divalent C 1 -C 10 organic group which may have fluorine or oxygen substituted thereon,
R 2 , R 3 and R 4 are each independently a substituted or unsubstituted, straight or branched C 1 -C 10 alkyl, alkenyl or oxoalkyl group or a substituted or unsubstituted C 6 -C 18 aryl, aralkyl or aryloxoalkyl group, or at least two of R 2 , R 3 and R 4 may bond together to form a ring with the sulfur atom to which they are attached,
N is an integer of 0 to 2,
R 8 is hydrogen or C 1 -C 10 alkyl,
B is a single bond or a divalent C 1 -C 10 organic group which may have oxygen substituted thereon,
a is an integer of 0 to 3,
b is an integer of 1 to 3, and
X is an acid labile group.