Intrinsic Stress of DLC Film Prepared by RF Plasma CVD and Filteredcathodic ARC PVD

Summary form only given. Diamond-like carbon (DLC) films frequently exhibit poor adhesion strength and delaminate instantly due to high internal compressive stress , as high as 8.5 GPa generated in the film, thus resulting in the limitation of the film. Our recent experimental results suggest a functional relationship between the intrinsic compressive stress and the negative biasing voltage applied to the substrate. For the first time, we have obtained DLC compressive stress data as a function of DC bias voltage for films prepared from the C₂H₂ RF plasma and we compare them with data obtained from the cathodic arc. Although the deposition rate was different, the DLC deposition rate of the filtered cathodic arc being ~1 nm per sec. while the rate in the RF process is approximately 2 nm per min., a similar trend in the stress generation and the stress-relief region was observed in both methods of deposition. The motivation for this study was to establish a coating methodology for DLC that yields a high sp³:sp² ratio and strong adhesion strength. Such a coating is expected to be hard but not easily delaminated, and would be useful when coated on to steel substrates such as industrial cutting tools, to enhance life performance and cost savings. The preliminary results showed that a thicker DLC film can be obtained by incorporating a lower stress, graphitic layer or a silicon layer.