Polymers for 193-nm Microlithography: Regioregular 2-Alkoxycarbonylnortricyclene Polymers by Controlled Cyclopolymerization of Bulky Ester Derivatives of Norbornadiene

Double duty for the tert-butyl residue: The bulky substituent in monomer 1 favors free-radical cyclopolymerization with maleic anhydride to give the regioregular nortricyclene copolymer 2. When the polymer is irradiated with a photoacid generator, the tert-butyl ester is cleaved and the polymer becomes soluble in aqueous base. This type of copolymer can be used in 193-nm microlithography; images with resolutions of less than 200 nm have been obtained.