Aging of fluorocarbon thin films deposited on polystyrene from hyperthermal C3F5+ and CF3+ ion beams

Fluorocarbon films grown on polystyrene (PS) in vacuum from 25-100 eV CF3and C3F5+ ions are aged by exposure to atmosphere for 4 and 8 weeks, then a nalyzed by X-ray photoelectron spectroscopy. atomic force microscopy, and w ater contact angle measurements. These fluorocarbon films oxidize with time , showing an increase in their oxygen/carbon ratio and a decrease in their fluorine/carbon ratio. The decrease in fluorine/carbon ratio with aging is due not only to increased oxygen content, but also to surface restructuring and release of low molecular weight oxidized material from the surface. Th e higher oxidation and surface restructuring observed upon aging for 100 eV C3F5+ and 50 eV CF3+ ion-modified PS can be additionally attributed to hig her surface bond breakage and active site formation. 100 eV C3F5+ and 50 eV CF3+ ion-modified PS surfaces are rougher than the 50 eV C3F5+ ion-modifie d PS. Overall, the aging process of these ion-deposited films appears simil ar to that of plasma-deposited films.