Atmospheric Pressure PECVD of Fluorocarbon Coatings from Glow Dielectric Barrier Discharges

The deposition of fluorocarbon films from GDBDs fed with helium-hexafluoropropene (He-C3F6) and helium-octafluoropropane-hydrogen (He-C3F8-H-2) mixtures was investigated. The effect of several parameters was evaluated in order to clarify both the GDBD existence domain and film characteristics. He-C3F6 GDBDs allowed to obtain films with an F/C ratio of 1.5 and to achieve deposition rates up to 35 nm . min (-1). By changing the H-2 content in He-C3F8-H-2 fed GDBDs it was possible to vary the crosslinking degree, to tune the F/C ratio of the coatings and to change the deposition rate which was maximized for an H-2/C3F8 ratio close to 1. A spectroscopic investigation of the plasma phase is also presented.