Abstract: Acid-labile group protected hydroxystyrene polymers having recurrent pendant groups such as 1-(2-methanecarbonyl oxyethoxy)ethoxy group and 1-(2-N-methylcarbamatoethoxy) ethoxy group. A resist containing the polymer, a photo acid generator, a base, additives and a solvent is sensitive to UV, electron beam and X-ray. In the resist, acid is formed in the exposed area during irradiation, which deprotects acid-labile group catalytically during application of post-exposure baking. Positive patterns are formed after development using an alkaline solution.