A study of atmospheric-pressure CHF₃/Ar plasma treatment on dielectric characteristics of polyimide films

In this work, the influence of atmospheric-pressure CHF₃/Ar plasma treatment on surface dielectric properties of polyimide films was investigated using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurements. The dielectric characteristics of the films were studied using a dielectric spectrometer. From the results, it was found that the plasma treatment introduced fluorine functional groups onto the polyimide surfaces. F_1s/C_1s ratios of the polyimides were enhanced with the increase of plasma treatment time. Consequently, the fluorine groups led to a decrease of the surface free energy and dielectric constant of the polyimide films, which can largely be attributed to the decrease of the deformation polarizability or London dispersive component of surface free energy of the solid surface studied.