CF4/O2 plasma etching and surface modification of polyimide films: Time-dependent surface fluorination and fluorination model

Abstract

The interaction of CF4/O2plasma mixtures with polyimide pyromellitic dianhydride–oxydianiline (PMDA‐ODA) films is a complex process. In this investigation, the reactions of PMDA‐ODA with a gas mixture containing 90% CF4/10% O2, as a function of treatment time, are studied with x‐ray photoelectron spectroscopy(XPS).Curve fitting of the resulting spectra yields the distribution of CF x species formed during reaction. A detailed reaction mechanism of F atom addition to PMDA‐ODA is constructed on a simplified monomer unit. The experimental results fitted to the proposed model yield apparent reaction rate constants and the time dependent concentration of unstable surface species in the reaction zone.