Tetrafluoroethylene-based Fluoropolymers for 157-nm Resist Materials

Abstract

Tetrafluoroethylene-based copolymers with functional norbornenes were synthesized and their fundamental properties, such as transparency at 157 nm and solubility in a standard alkaline developer, were characterized. A high transparency, i.e., absorbance of less than 0.5 μm^-1, was achieved by optimizing the polymerization conditions with a variety of functional norbornene monomers. Positive-working resists formulated by the fluororesins were developed and showed good transparency of less than 1 μm^-1 at 157 nm, and good developability without any swelling behavior in a standard alkaline solution of 0.26-N tetramethylammonium hydroxide, and an acceptable dry-etching resistance as good as ArF resists. And fine patterns of 65-nm dense lines and spaces could be delineated by the exposure at 157-nm wavelength.