Patent ID: 7968275

Claim:
A method of forming a photoresist pattern comprising: preparing a photoresist composition for immersion lithography including a photosensitive polymer having a cycloaliphatic group blocked with at least two cyclic acetal groups as a side chain, a photoacid generator and an organic solvent; wherein the photosensitive polymer includes a monomer represented by Formula 2, wherein R 1 to R 12 independently represent a hydrogen atom, a C 1 -C 10 aliphatic group, a C 3 -C 10 cycloaliphatic group or a C 3 -C 10 aryl group; or wherein the photosensitive polymer includes a monomer represented by Formula 4, wherein R 1 to R 12 independently represent a hydrogen atom, a C 1 -C 10 aliphatic group, a C 3 -C 10 cycloaliphatic group or a C 3 -C 10 aryl group; forming a photoresist film on an object using the photoresist composition; providing a liquid for the immersion lithography between the photoresist film and immersion lithography device; exposing the photoresist film using the immersion lithography device; and developing the photoresist film.