Characterization of Polymer Thin Films Prepared with RF Sputtering with Fluorocarbon Polymer Targets

Abstract

  Polymer thin films were prepared by RF sputtering with argon (Ar) and tetra-fluorocarbon (CF₄) gases. Four fluorocarbon polymers, poly(tetra fluoro ethylene) (PTFE), tetra fluoro ethylene-perfluoro alkylvinyl ether copolymer (PFA), fluorinated ethylene propylene copolymer (FEP), poly(vinylidene di fluoride) (PVDF) were used as the sputtering targets. Molecular structures of sputtered fluorocarbon thin films were analyzed with x-rays photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FT-IR). Wettability of these polymer thin films was estimated with contact angles of water droplets. The contact angles increased with increase of the F/C ratio (fluorine for carbon) of the thin film. PTFE target prepared by a spin coat method was also used for the sputtering target, and analyzed the elemental compositions of the target after the sputtering. The F/C ratio of the polymer thin film prepared by the sputtering with CF₄ was almost the same value as that of the thin film with Ar. However, the C/F ratio of the target after the CF₄ sputtering was much higher than that after the Ar sputtering.