Deposition and etching of fluorocarbon thin films in atmospheric pressure DBDs fed with Ar-CF4-H2 and Ar-CF4-O2 mixtures

The deposition and etching of plasma-polymerized fluorocarbon thin films were studied in filamentary dielectric barrier discharges (FDBDs) fed with Ar-CF4-H-2 and Ar-CF4-O-2 mixtures, respectively. The etching/polymerization competition was investigated as a function of the feed composition. Hydrogen addition to CF4 promotes thin films deposition, with a maximum deposition rate at 20% H-2, and reduces the F/C ratio of the deposit, while the oxygen addition promotes the etching of the plasma-deposited film. It is demonstrated that fluorine atoms can perform the etching of the fluoropolymer also without ion bombardment. The correlation between the trend of the etch rate and the trend of the surface chemical composition of fluoropolymers etched in Ar-CF4-O-2 mixtures allows to enhance hypotheses on the reaction mechanism and on the role of the different active species involved in plasma-surface interactions. (C) 2009 Elsevier B.V. All rights reserved.