US Patent 7125642 Sulfonates, polymers, resist compositions and patterning process

A sulfonate compound having formula (1) is novel wherein R1 to R3 are H, F or C1-20 alkyl or fluoroalkyl, at least one of R1 to R3 contains F. A polymer comprising units derived from the sulfonate compound is used as a base resin to formulate a resist composition which is sensitive to high-energy radiation, maintains high transparency at a wavelength of up to 200 nm, and has improved alkali dissolution contrast and plasma etching resistance