Patterning process, resist composition, and acetal compound

摘要

A pattern is formed by applying a resist composition comprising a polymer comprising recurring units having an acid labile group-substituted hydroxyl group, an acid generator, and an organic solvent onto a substrate, prebaking the composition to form a resist film, exposing the resist film to high-energy radiation to define exposed and unexposed regions, baking, and developing the exposed film with an organic solvent developer to form a negative pattern wherein the unexposed region of film is dissolved and the exposed region of film is not dissolved.