Cycloolefin/maleic anhydride copolymers for 193-nm resist compositions

Several novel norbornene carboxylate monomers consisting of isobornyl and alkyl ether chains on the ester groups were synthesized and polymerized with maleic anhydride (MA), t- butylnorbornene carboxylate (BNC), hydroxyethylnorbornene carboxylate (HNC) and norbornene carboxylic acid (NC). These polymers were compared with BNC/HNC/NC/MA tetra-polymers with respect to glass transition temperature (Tg) as well as photoresist performance using a 193 nm exposure tool. It was observed that introduction of these groups decreases the Tg but not to the extent where the polymers can be used as an annealing type resist. The synthesis of these polymers, their characterization, and their lithographic evaluation as 193 resists will be discussed in this paper. Further optimization in terms of final polymer composition as well as resist formulation is on-going in order to fully exploit these monomers for photoresist application.