Synthesis of Polytetrafluoroethylene-like Films by a Novel Plasma Enhanced Chemical Vapor Deposition Employing Solid Material Evaporation Technique

Abstract

Polytetrafluoroethylene (PTFE)-like films were formed by electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition (ECR-PECVD) employing the solid material evaporation technique where the PTFE was evaporated by a CO2 laser resulting in the production of fluorocarbon species. This system does not employ any perfluorocompound (PFC) feed gases which cause global warming. In this system, it was found that C2F4 and higher species such as CxFy (x≥2) were generated by CO2 laser evaporation. The films were analyzed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared absorption spectroscopy (FT-IR). As a result, the chemical composition of films formed at microwave powers below 0.4 kW indicated a PTFE-like structure with an F/C ratio of 2.0 and a dielectric constant of 2.0. Densities of CFx (x=1–3) radicals and F atoms in the ECR plasma employing the solid material evaporation technique were measured to understand the behavior of these radicals by infrared diode laser absorption spectroscopy (IRLAS) and actinometric optical spectroscopy (AOES), respectively. From these measurements, higher species of C2F4 and CxFy were clarified to be the important precursors of PTFE-like fluorocarbon films.