Structure and chemical composition of polymer films deposited in a dielectric barrier discharge (DBD) in Ar/fluorocarbon mixtures

Abstract The properties of fluorocarbon polymer films deposited on Si wafers, foils, and technical textiles in a DBD at atmospheric pressure have been studied. Fourier transform infrared (FTIR) absorption spectroscopy and X-ray photo electron spectroscopy (XPS) were applied to get information on the atomic content and structure of the deposited polymer films in dependence on fluorocarbon molecules CF 4 , C 2 F 6 , C 3 HF 7 , C 2 H 2 F 4 , C 3 F 8 and c -C 4 F 8 . Analysis of the XPS-spectra indicates that polymer films can be deposited if the F/C ratio of the starting fluorocarbon molecules is smaller, or close to 3. FTIR-absorption spectra of films on Si wafers show an “amorphous” film structure with the main absorption peak of CF 2 -groups at 1200 cm −1 . By variation of the F/C ratio it could be shown that plasma polymerisation correlates strongly to the appearance of an “amorphous” PTFE absorption peak at 740 cm −1 in the FTIR-absorption spectra in the DBD. H-atoms in the starting fluorocarbon molecules as well as admixture of hydrogen influence the cross linking effects in the film during plasma polymerisation process.