Polymer, resist composition, and patterning process
A polymer obtained through copolymerization of a monomer having a hexafluoroalcohol pendant whose hydroxyl moiety has been protected and a monomer having an acid labile group is useful as an additive to a photoresist composition for immersion lithography. When processed by immersion lithography, the resist composition exhibits good water repellency and water slip and produces few development defects.
1. A resist composition comprising (A1) a polymer comprising repeat units of the general formulae (1a), (2) and (3), (B) a polymer having a lactone ring and/or maleic anhydride-derived structure which becomes soluble in an alkaline developer under the action of an acid, (C) a compound capable of generating an acid upon exposure to high-energy radiation, and (D) an organic solvent, wherein the amount of polymer (A1) is 0.5 to 10 parts by weight per 100 parts by weight of polymer (B),
wherein R 1 is hydrogen, fluorine, or straight or branched C 1 -C 4 alkyl or fluoroalkyl, R 2a and R 2b are hydrogen or straight, branched or cyclic C 1 -C 10 alkyl, R 3a and R 3b are hydrogen or straight, branched or cyclic C 1 -C 6 alkyl, R 3c is straight, branched or cyclic C 1 -C 10 alkyl, R 4a and R 4b are hydrogen or straight, branched or cyclic C 1 -C 10 alkyl, R 5 is hydrogen, straight, branched or cyclic C 1 -C 10 alkyl, or an acid labile group, R 6 is an acid labile group, R 2a and R 2b , and R 4a and R 4b may bond together to form a non-aromatic ring of 1 to 20 carbon atoms with the carbon atom to which they are attached, m is an integer of 1 to 6, a1, a2 and a3 are numbers satisfying 0.4≦a1≦0.9, 0≦a2≦0.6, 0≦a3≦0.6, 0<a2+a3≦0.6 and 0<a1+a2+a3≦1.
2. The resist composition of claim 1 , further comprising (E) a basic compound.
3. The resist composition of claim 1 , further comprising (F) a dissolution inhibitor.
4. A pattern forming process comprising the steps of (1) applying the resist composition of claim 1 onto a substrate to form a resist coating, (2) heat treating the resist coating and exposing it to high-energy radiation through a photomask, and (3) developing the exposed coating with a developer.
5. The process of claim 4 wherein the high-energy radiation has a wavelength in the range of 180 to 250 nm.
6. A pattern forming process comprising the steps of (1) applying the resist composition of claim 1 onto a substrate to form a resist coating, (2) heat treating the resist coating and exposing it to high-energy radiation from a projection lens through a photomask while holding a liquid between the substrate and the projection lens, and (3) developing the exposed coating with a developer.
7. The process of claim 6 wherein the liquid is water.
8. A pattern forming process comprising the steps of (1) applying the resist composition of claim 1 onto a substrate to form a resist coating, (2) forming a protective coating onto the resist coating, (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.
9. A pattern forming process comprising the steps of (1) applying the resist composition of claim 1 onto a mask blank to form a resist coating, (2) heat treating and exposing the resist coating in vacuum to electron beam, and (3) developing with a developer.