Resist protective coating composition and patterning process
A protective coating composition comprising a polymer of acyl-protected hexafluoroalcohol structure as a base polymer, optionally in admixture with a second polymer containing sulfonic acid amine salt in recurring units is applied onto a resist film. The protective coating is transparent to radiation of wavelength up to 200 nm.
1. A pattern forming process comprising the steps of (1) applying a resist material onto a substrate to form a photoresist film, (2) applying a resist protective coating composition onto the photoresist film to form a protective coating thereon, (3) heat treating and exposing the coated substrate to high-energy radiation from a projection lens through a photomask while holding a liquid between the substrate and the projection lens, and (4) developing with a developer,
said resist protective coating composition comprising a polymer P1 comprising recurring units of the general formula (1):
wherein R 1 is hydrogen, methyl or trifluoromethyl, R 2a and R 2b are hydrogen or straight, branched or cyclic C 1 -C 15 alkyl, R 2a and R 2b may bond together to form a ring with the carbon atom to which they are attached, R 3 is a single bond or straight, branched or cyclic C 1 -C 15 alkylene, and R 4 is a straight, branched or cyclic C 1 -C 20 alkyl or fluoroalkyl.
2. The process of claim 1 wherein the liquid is water.
3. The process of claim 1 wherein the high-energy radiation has a wavelength in the range of 180 to 250 nm.
4. The process of claim 1 wherein the developing step uses a liquid alkaline developer for thereby developing the photoresist film to form a resist pattern and stripping the resist protective coating therefrom at the same time.
5. The pattern forming process of claim 1 , wherein said polymer P1 further comprises recurring units of at least one type selected from the general formulae (2a), (2b), (2c), (2e) and (2f):
wherein R 1 is hydrogen, methyl or trifluoromethyl, R 2a and R 2b are hydrogen or straight, branched or cyclic C 1 -C 15 alkyl, R 2a and R 2b may bond together to form a ring with the carbon atom to which they are attached, R 5 is hydrogen, or a straight, branched or cyclic C 1 -C 15 alkyl or fluoroalkyl, or an acid labile group, and R 6 is a straight, branched or cyclic C 1 -C 15 fluoroalkyl.
6. The pattern forming process of claim 1 , wherein the protective coating composition further comprises a polymer P2 comprising recurring units of the general formula (3) or (4):
wherein:
R 21a and R 21b are hydrogen or methyl,
R 22 is a single bond, C 1 -C 4 alkylene, phenylene, —C(═O)—, or —C(═O)—NH—,
R 23 is a single bond or straight, branched or cyclic C 1 -C 8 alkylene,
R 24a to R 24d and R 26a to R 26c are each independently selected from the group consisting of hydrogen, straight, branched or cyclic C 1 -C 12 alkyl, alkenyl, oxoalkyl and oxoalkenyl, C 6 -C 20 aryl, C 7 -C 12 aralkyl and aryloxoalkyl, in which some or all hydrogen atoms may be substituted by alkoxy groups, R 24a to R 24d and R 26a to R 26c may contain a nitrogen atom, ether, ester, hydroxyl or carboxyl group, any two of R 24a to R 24d and any two of R 26a to R 26c may bond together to form a ring with the nitrogen atom to which they are attached, in this event, each participant in the ring formation independently denotes a C 3 -C 15 alkylene or a hetero-aromatic ring containing the nitrogen atom therein,
R 25 is straight, branched or cyclic C 1 -C 8 alkylene, and
R 27 is a straight, branched or cyclic C 1 -C 20 alkyl which may have a carbonyl, ester, ether group or halogen atom, or a C 6 -C 15 aryl which may have a carbonyl, ester, ether, halogen atom, or C 1 -C 15 alkyl or fluoroalkyl.
7. The pattern forming process of claim 6 , wherein said polymer P2 further comprises recurring units of the general formula (5):
wherein R 21c is hydrogen or methyl, R 28a and R 28b are hydrogen or straight, branched or cyclic C 1 -C 15 alkyl, and R 28a and R 28b may bond together to form a ring with the carbon atom to which they are attached.
8. The pattern forming process of claim 1 , wherein the protective coating composition further comprises a solvent.
9. The pattern forming process of claim 8 , wherein the solvent comprises an ether compound of 8 to 12 carbon atoms.
10. The pattern forming process of claim 9 , wherein the solvent comprises at least one ether compound of 8 to 12 carbon atoms selected from the group consisting of di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-t-amyl ether, and di-n-hexyl ether.
11. The pattern forming process of claim 8 , wherein the solvent comprises a mixture of an ether compound and 0.1 to 90% by weight of a higher alcohol of 4 to 10 carbon atoms.
12. A lithography process for forming a pattern, comprising the steps of forming a protective coating on a photoresist layer disposed on a mask blank, exposing the layer structure in vacuum to electron beam, and developing,
the protective coating being formed of a protective coating composition comprising a polymer P1 comprising recurring units of the general formula (1):
wherein R 1 is hydrogen, methyl or trifluoromethyl, R 2a and R 2b are hydrogen or straight, branched or cyclic C 1 -C 15 alkyl, R 2a and R 2b may bond together to form a ring with the carbon atom to which they are attached, R 3 is a single bond or straight, branched or cyclic C 1 -C 15 alkylene, and R 4 is a straight, branched or cyclic C 1 -C 20 alkyl or fluoroalkyl.
13. The lithography process of claim 12 , wherein said polymer P1 further comprises recurring units of at least one type selected from the general formulae (2a), (2b), (2c), (2e) and (20f):
wherein R 1 is hydrogen, methyl or trifluoromethyl, R 2a and R 2b are hydrogen or straight, branched or cyclic C 1 -C 15 alkyl, R 2a and R 2b may bond together to form a ring with the carbon atom to which they are attached, R 5 is hydrogen, or a straight, branched or cyclic C 1 -C 15 alkyl or fluoroalkyl, or an acid labile group, R 6 is a straight, branched or cyclic C 1 -C 15 fluoroalkyl.
14. The lithography process of claim 12 , wherein the protective coating composition further comprises a polymer P2 comprising recurring units of the general formula (3) or (4):
wherein:
R 21a and R 21b are hydrogen or methyl,
R 22 is a single bond, C 1 -C 4 alkylene, phenylene, or —C(═O)—, or —C(═O)—NH—,
R 23 is a single bond or straight, branched or cyclic C 1 -C 8 alkylene,
R 24a to R 24d and R 26a to R 26c are each independently selected from the group consisting of hydrogen, straight, branched or cyclic C 1 -C 12 alkyl, alkenyl, oxoalkyl and oxoalkenyl, C 6 -C 20 aryl, C 7 -C 12 aralkyl and aryloxoalkyl, in which some or all hydrogen atoms may be substituted by alkoxy groups, R 24a to R 24d and R 26a to R 26c may contain a nitrogen atom, ether, ester, hydroxyl or carboxyl group, any two of R 24a to R 24d and any two of R 26a to R 26c may bond together to form a ring with the nitrogen atom to which they are attached, in this event, each participant in the ring formation independently denotes a C 3 -C 15 alkylene or a hetero-aromatic ring containing the nitrogen atom therein,
R 25 is straight, branched or cyclic C 1 -C 8 alkylene, and
R 27 is a straight, branched or cyclic C 1 -C 20 alkyl which may have a carbonyl, ester, ether group or halogen atom, or a C 6 -C 15 aryl which may have a carbonyl, ester, ether, halogen atom, or C 1 -C 15 alkyl or fluoroalkyl.
15. The lithography process of claim 14 , wherein said polymer P2 further comprises recurring units of the general formula (5):
wherein R 21c is hydrogen or methyl, R 28a and R 28b are hydrogen or straight, branched or cyclic C 1 -C 15 alkyl, and R 28a and R 28b may bond together to form a ring with the carbon atom to which they are attached.
16. The lithography process of claim 12 , wherein the protective coating composition further comprises a solvent.
17. The lithography process of claim 16 , wherein the solvent comprises an ether compound of 8 to 12 carbon atoms.
18. The lithography process of claim 17 , wherein the solvent comprises at least one ether compound of 8 to 12 carbon atoms selected from the group consisting of di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-t-amyl ether, and di-n-hexyl ether.
19. The lithography process of claim 16 , wherein the solvent comprises a mixture of an ether compound and 0.1 to 90% by weight of a higher alcohol of 4 to 10 carbon atoms.