Effects of Deposition Conditions on Adhesion of DLC Films Prepared by UBM Sputtering

The adhesion of diamondlike carbon (DLC) films deposited on SKD11 substrates by Unbalanced Magnetron sputtering (UBMS) of a metal Cr and graphite target was investigated. DLC films, consist of Cr/C gradient interlayer and a-C:H layer, were prepared under various deposition conditions, and film-substrate adhesion was evaluated using adhesion energy equation proposed in our previous study. This equation was improved on the base of that of Bull et.al. with taking into consideration the compressive residual stress in the film. Deposition conditions (substrate bias voltage, ratio of CH4 gas flow rate (CH4 flow rate per total Ar and CH4 gas), deposition temperature, deposition pressure, deposition time) were varied. From scanning electron microscope (SEM) observation of cross section of the film and analysis of electron probe micro analyzer (EPMA) for the detached area of the scratch track, it was confirmed that the films detached in the Cr/C interlayer. Adhesion energy changed characteristically and depended on the deposition conditions and corresponded to the Young's modulus of the film.