US Patent 9244350 Positive resist composition and patterning process

A positive resist composition is provided comprising a polymer comprising recurring units having a carboxyl or phenolic hydroxyl group substituted with an acid labile group and recurring units of hydroxyanthraquinone or hydroxy-2,3-dihydro-1,4-anthracenedione methacrylate, and having a Mw of 1,000-500,000. The resist composition has a satisfactory effect of suppressing acid diffusion and a high resolution, and forms a pattern of good profile and minimal edge roughness after exposure.