Resist composition and patterning process
A resist composition comprising a base polymer and a sulfonium salt of amino-containing carboxylic acid offers dimensional stability on PPD and a satisfactory resolution.
1. A resist composition comprising a base polymer, a photoacid generator, and a sulfonium salt having the formula (A):
wherein R 1 is hydrogen or a straight, branched or cyclic C 1 -C 6 alkyl group,
R 2 is selected from the group consisting of hydrogen, straight, branched or cyclic C 1 -C 6 alkyl, acetyl, methoxycarbonyl, ethoxycarbonyl, n-propyloxycarbonyl, isopropyloxycarbonyl, t-butoxycarbonyl, t-pentyloxycarbonyl, methylcyclopentyloxycarbonyl, ethylcyclopentyloxycarbonyl, methylcyclohexyloxycarbonyl, ethylcyclohexyloxycarbonyl, 9-fluorenylmethyloxycarbonyl, allyloxycarbonyl, phenyl, benzyl, naphthyl, naphthylmethyl, methoxymethyl, ethoxymethyl, propoxymethyl, and butoxymethyl,
R 3 and R 4 are each independently hydrogen, or a straight, branched or cyclic C 1 -C 12 alkyl group, C 6 -C 20 aryl group, C 2 -C 12 alkenyl group or C 2 -C 12 alkynyl group which may contain an ester, ether, sulfide, sulfoxide, sulfone, halogen, amino, amide, hydroxy, thiol or nitro moiety, R 3 and R 4 , taken together, may form a double bond, with the proviso that the total number of carbon atoms in R 1 to R 4 is at least 7 when R 3 and R 4 are free of fluorine, and the total number of carbon atoms in R 1 to R 4 is at least 1 when R 3 and R 4 contain fluorine,
R 5 , R 6 and R 7 are each independently a straight, branched or cyclic C 1 -C 12 alkyl or oxoalkyl group, a straight, branched or cyclic C 2 -C 12 alkenyl or oxoalkenyl group, C 6 -C 20 aryl group, or C 7 -C 12 aralkyl or aryloxoalkyl group, in which at least one hydrogen may be substituted by a substituent containing an ether, ester, carbonyl, carbonate, hydroxyl, carboxyl, halogen, cyano, amide, nitro, sultone, sulfonic acid ester, sulfone moiety or sulfonium salt, or R 5 and R 6 may bond together to form a ring with the sulfur atom to which they are attached.
2. The resist composition of claim 1 , wherein the photoacid generators an acid generator capable of generating sulfonic acid, imide acid or methide acid.
3. The resist composition of claim 1 , further comprising an organic solvent.
4. The resist composition of claim 1 wherein the base polymer comprises recurring units having the general formula (a1) or recurring units having the general formula (a2):
wherein R 11 and R 13 are each independently hydrogen or methyl, R 12 and R 14 are each independently an acid labile group, X is a single bond, ester group, phenylene group, naphthylene group or a C 1 -C 12 linking group containing lactone ring, and Y is a single bond or ester group.
5. The resist composition of claim 4 , further comprising a dissolution inhibitor.
6. The resist composition of claim 4 which is a chemically amplified positive resist composition.
7. The resist composition of claim 1 wherein the base polymer is free of an acid labile group.
8. The resist composition of claim 7 , further comprising a crosslinker.
9. The resist composition of claim 7 which is a chemically amplified negative resist composition.
10. The resist composition of claim 1 wherein the base polymer comprises recurring units of at least one type selected from the formulae (f1) to (f3):
wherein R 51 , R 55 and R 59 each are hydrogen or methyl,
R 52 is a single bond, phenylene, —O—R 63 —, or —C(═O)—Y 1 —R 63 —, Y 1 is —O— or —NH—, R 63 is a straight, branched or cyclic C 1 -C 6 alkylene or C 2 -C 6 alkenylene group which may contain a carbonyl, ester, ether or hydroxyl moiety, or phenylene group,
R 53 , R 54 , R 56 , R 57 , R 58 , R 60 , R 61 , and R 62 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 group, C 7 -C 20 aralkyl group or mercaptophenyl group,
A 1 is a single bond, -A 0 -C(═O)—O—, -A 0 -O— or -A 0 -O—C(═O)—, A 0 is a straight, branched or cyclic C 1 -C 12 alkylene group which may contain a carbonyl, ester or ether moiety,
A 2 is hydrogen or trifluoromethyl,
Z 1 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, —O—R 64 —, or —C(═O)—Z 2 —R 64 —, Z 2 is —O— or —NH—, R 64 is a straight, branched or cyclic C 1 -C 6 alkylene or C 2 -C 6 alkenylene group which may contain a carbonyl, ester, ether or hydroxyl moiety, or phenylene, fluorinated phenylene or trifluoromethyl-substituted phenylene group,
M − is a non-nucleophilic counter ion, and f1, f2 and f3 are numbers in the range: 0≤f1≤0.5, 0≤f2≤0.5, 0≤f3≤0.5, and 0<f1+f2+f3≤0.5.
11. The resist composition of claim 1 , further comprising a surfactant.
12. A process for forming a pattern comprising the steps of applying the resist composition of claim 1 onto a substrate, baking to form a resist film, exposing the resist film to high-energy radiation, and developing the exposed film in a developer.
13. The process of claim 12 wherein the high-energy radiation is ArF excimer laser radiation of wavelength 193 nm or KrF excimer laser radiation of wavelength 248 nm.
14. The process of claim 12 wherein the high-energy radiation is electron beam or extreme ultraviolet radiation of wavelength 3 to 15 nm.
15. A resist composition comprising a base polymer comprising recurring units of at least one type selected from the formulae (f1) to (f3), and a sulfonium salt having the formula (A):
wherein R 1 is hydrogen or a straight, branched or cyclic C 1 -C 6 alkyl group,
R 2 is selected from the group consisting of hydrogen, straight, branched or cyclic C 1 -C 6 alkyl, acetyl, methoxycarbonyl, ethoxycarbonyl, n-propyloxycarbonyl, isopropyloxycarbonyl, t-butoxycarbonyl, t-pentyloxycarbonyl, methylcyclopentyloxycarbonyl, ethylcyclopentyloxycarbonyl, methylcyclohexyloxycarbonyl, ethylcyclohexyloxycarbonyl, 9-fluorenylmethyloxycarbonyl, allyloxycarbonyl, phenyl, benzyl, naphthyl, naphthylmethyl, methoxymethyl, ethoxymethyl, propoxymethyl, and butoxymethyl,
R 3 and R 4 are each independently hydrogen, or a straight, branched or cyclic C 1 -C 12 alkyl group, C 6 -C 20 aryl group, C 2 -C 12 alkenyl group or C 2 -C 12 alkynyl group which may contain an ester, ether, sulfide, sulfoxide, sulfone, halogen, amino, amide, hydroxy, thiol or nitro moiety, R 3 and R 4 , taken together, may form a double bond, with the proviso that the total number of carbon atoms in R 1 to R 4 is at least 7 when R 3 and R 4 are free of fluorine, and the total number of carbon atoms in R 1 to R 4 is at least 1 when R 3 and R 4 contain fluorine, and
R 5 , R 6 and R 7 are each independently a straight, branched or cyclic C 1 -C 12 alkyl or oxoalkyl group, a straight, branched or cyclic C 2 -C 12 alkenyl or oxoalkenyl group, C 6 -C 20 aryl group, or C 7 -C 12 aralkyl or aryloxoalkyl group, in which at least one hydrogen may be substituted by a substituent containing an ether, ester, carbonyl, carbonate, hydroxyl, carboxyl, halogen, cyano, amide, nitro, sultone, sulfonic acid ester, sulfone moiety or sulfonium salt, or R 5 and R 6 may bond together to form a ring with the sulfur atom to which they are attached,
wherein R 51 , R 55 and R 59 each are hydrogen or methyl,
R 52 is a single bond, phenylene, —O—R 63 — or —C(═O)—Y 1 —R 63 —, Y 1 is —O— or —NH—, R 63 is a straight, branched or cyclic C 1 -C 6 alkylene or C 2 -C 6 alkenylene group which may contain a carbonyl, ester, ether or hydroxyl moiety, or phenylene group,
R 53 , R 54 , R 56 , R 57 , R 58 , R 60 , R 61 , and R 62 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 group, C 7 -C 20 aralkyl group or mercaptophenyl group,
A 1 is a single bond, -A 0 -C(═O)—O—, -A 0 -O— or -A 0 -O—C(═O)—, A 0 is a straight, branched or cyclic C 1 -C 12 alkylene group which may contain a carbonyl, ester or ether moiety,
A 2 is hydrogen or trifluoromethyl,
Z 1 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, —O—R 64 —, or —C(═O)—Z 2 —R 64 —, Z 2 is —O— or —NH—, R 64 is a straight, branched or cyclic C 1 -C 6 alkylene or C 2 -C 6 alkenylene group which may contain a carbonyl, ester, ether or hydroxyl moiety, or phenylene, fluorinated phenylene or trifluoromethyl-substituted phenylene group, and
M − is a non-nucleophilic counter ion, and f1, f2 and f3 are numbers in the range: 0≤f1≤0.5, 0≤f2≤0.5, 0≤f3≤0.5, and 0<f1+f2+f3≤0.5.
16. The resist composition of claim 15 wherein the base polymer comprises recurring units having the general formula (a1) or recurring units having the general formula (a2):
wherein R 11 and R 13 are each independently hydrogen or methyl, R 12 and R 14 are each independently an acid labile group, X is a single bond, ester group, phenylene group, naphthylene group or a C 1 -C 12 linking group containing lactone ring, and Y is a single bond or ester group.
17. The resist composition of claim 16 , which is a chemically amplified positive resist composition.
18. The resist composition of claim 15 , wherein the base polymer is free of an acid labile group.
19. The resist composition of claim 18 , which is a chemically amplified negative resist composition.
20. A process for forming a pattern comprising the steps of applying the resist composition of claim 15 onto a substrate, baking to form a resist film, exposing the resist film to high-energy radiation, and developing the exposed film in a developer.