A ternary copolymer comprising units of -trifluoromethylacrylic carboxylate having acid labile groups substituted thereon, units of -trifluoromethylacrylic carboxylate having adhesive groups substituted thereon, and units of styrene having hexafluoroalcohol pendants is highly transparent to VUV radiation and resistant to plasma etching. A resist composition using the polymer as a base resin is sensitive to high-energy radiation below 200 nm, has excellent sensitivity, and is suited for lithographic microprocessing.