Disclosed herein is a photoacid generating polymer represented by Formula 1 below: ##STR00001## wherein R.sub.1 is a C.sub.1-10 hydrocarbon or a C.sub.1-10 hydrocarbon in which the hydrogen atoms are wholly or partly replaced by fluorine atoms; R.sub.2 is hydrogen or a methyl group; and a, b, c and d represent the mole fraction of each monomer and are in the range between about 0.05 and about 0.9, such that the sum of a, b, c, and d equals one. Since the photoacid generating polymer of Formula 1 is not water-soluble and acts as a photoacid generator, it can be used to prepare a top anti-reflective coating composition for immersion lithography.