US Patent 7135269 Polymer, resist composition and patterning process

A polymer comprising recurring units containing silicon and recurring units having a substituent group of formula (1) is novel wherein A1 is a divalent group selected from furandiyl, tetrahydrofurandiyl and oxanorbornanediyl, R1 and R2 are selected from monovalent C1–C10 hydrocarbon groups, or R1 and R2 taken together may form an aliphatic hydrocarbon ring with the carbon atom, and R3 is hydrogen or a monovalent C1–C10 hydrocarbon group which may contain a hetero atom. The polymer is useful as a base resin to formulate a resist composition which is sensitive to high-energy radiation, and has excellent sensitivity and resolution at a wavelength of less than 300 nm as well as satisfactory oxygen plasma etching resistance.