US Patent 7488567 Polymer, resist composition and patterning process

A polymer comprising recurring units of formula (1) wherein R1 is F or fluoroalkyl, R2 is alkylene or fluoroalkylene, and R3 is an acid labile group and having a Mw of 1,000-500,000 is used to formulate a resist composition, which is processed by the lithography involving ArF exposure and offers many advantages including resolution, minimal line edge roughness, etch resistance, and minimal surface roughness after etching. The composition performs well when processed by the ArF immersion lithography with liquid interposed between the projection lens and the wafer.