The O permeability of SiOx thin films on polyethylene terephthalate, produced by plasma-enhanced chemical vapor deposition from O-diluted hexamethyldisiloxane, was studied. The versatile plasma-enhanced chemical vapor deposition set-up, equipped with 2 plasma sources (remote microwave and direct radio-frequency), permitted the deposition of films with variable morphologies and compositions. The deposits were analyzed by X-ray photo-electron spectroscopy, ellipsometry, and atomic force microscopy. Curve-fitting of the Si 2p peak in X-ray photo-electron spectra provided

information about the chemical binding states of the Si atoms. The results clearly showed that the O transmission rate depended highly upon the film structure, whereas the chemical composition has only little effect. In order to achieve the desired dense and smooth film structure, it was necessary to have a high substrate bias, which promotes ion bombardment of the film surface during growth. Oxygen transmission rate values down to 0.2cm3(STP)/m2day, corresponding to a barrier improvement factor of 500, were achieved.

Influence of Film Structure and Composition on Diffusion Barrier Performance of SiOx Thin Films Deposited by PECVD. A.Grüniger, A.Bieder, A.Sonnenfeld, P.R.von Rohr, U.Müller, R.Hauert: Surface and Coatings Technology, 2006, 200[14-15], 4564-71