Ion beam assisted growth of dense diamond-like carbon

Abstract

Diamond-like carbon (DLC) films have been deposited using ion beam assisted PVD techniques in order to better understand the effect of a rare gas ion bombardment during growth on DLC properties. RBS and thickness determinations show that the density of the coatings, which is related to their diamond-like character, regularly increases with the ion flux. Optimal values of both the rare gas ion mass (between 2 amu and 131 amu) and ion energy (ranging from 0 to 300 eV) were found for a maximal densification of the carbon. Preferential displacement of sp 2 bonds can explain these results. The beam bending technique was used to demonstrate the strong influence of both the ion flux and ion energy on the stress values of the films, explaining cracking and peeling of the coatings for extreme bombardment conditions. Angle resolved XPS analysis was used to check if the ion bombardment induced modifications on the nature and thickness of the film-to-substrate interface. The ion bombardment reduced the thickness of the interface, sputtered partly Si O C film and favoured Si C bonds. This might lead to improved adhesion. These results give optimal conditions of the ion beam assistance depending on the desired applications of the coatings.