Patent ID: 8628911

Claim:
A method of forming a photolithographic pattern, comprising: (a) providing a substrate comprising one or more layer to be patterned over a surface of the substrate; (b) applying a layer of a photoresist composition over the one or more layer to be patterned, wherein the photoresist composition comprises: a polymer, comprising: a first unit formed from a monomer of the following general formula (I): wherein: P is a polymerizable group; R 1 represents a single bond, or a C 1 to C 10 linear or branched alkylene group, or a C 2 to C 10 linear or branched alkenylene group; or a C 1 to C 10 linear or branched organic group; R 2 and R 3 each independently represents a hydrogen atom or a C 1 to C 10 organic group, together optionally forming a ring; R 4 represents a hydrogen atom or a C 1 to C 10 organic group; and R 5 and R 6 each independently represents a C 1 to C 6 organic group, together optionally forming a ring; and a second unit comprising a lactone moiety; wherein the first unit is present in the polymer in an amount of from 30 to 60 mol %; and a photoacid generator; (c) patternwise exposing the photoresist composition layer to actinic radiation; (d) heating the exposed photoresist composition layer in a post-exposure bake process; and (e) applying an organic developer to the photoresist composition layer to remove a portion of the photoresist layer, thereby forming a photoresist pattern, wherein unexposed regions of the photoresist layer are removed by the organic developer to form the photoresist pattern.