Hydrophobic coatings deposited with an atmospheric pressure microplasma jet

Successful plasma polymerization of a fluorocarbon compound (c-C(4)F(8)) using an atmospheric pressure plasma jet is described. The source is operated with argon as working gas at a flow rate of 6 slm and 10-100 sccm admixtures of c-C(4)F(8). Deposition is limited to a discharge regime with strong localization and was observed for conductive substrates only (Al and Si). The deposition process is characterized by a high local growth rate (40 nm s(-1)) and produces films which show a Teflon-like chemical structure and hydrophobicity. The coatings are characterized using x-ray photoelectron spectroscopy, profilometry and scanning electron microscopy. Changing the ambient atmosphere from protective N(2) to normal air only reduces the deposition rate but does not change the chemistry of the film. Based on the results of parameter variations and the electrical relations of the jet setup, the special form of the deposition regime of the jet is discussed and considered to be a gamma-mode discharge dependent on the choice of substrate material.