Nanotribology of ultrathin a:SiC/SiC-N overcoats using a depth sensing nanoindentation multiple sliding technique

Conventional and reactive (Ar + N-2 atmosphere) magnetron sputtering were used to deposit amorphous SiC and SiC-N thin films, respectively. The ultrathin films (25 nm) were grown on Si(111), single crystal sapphire, and barium borosilicate glass substrates. A commercial nanoindentation system equipped with a continuous depth-sensing scratch option was utilized to assess wear and frictional behavior. Tangential or frictional forces were monitored via two proximity probes oriented in the plane of the film surface in the x- and y-directions, while the normal forces were concurrently generated. In situ surface wear displacement profiles of the films on different substrates were strongly dependent on their intrinsic elastic/plastic properties. For a constant load of 150 mu N under 31 multiple sliding scans, delamination only occurred in the SiC/sapphire system (27th scan) while the SiC/glass and Si(111) systems remained adhered. interestingly there was no debonding in the SiC-N/sapphire system, which also reflects how the technique can qualitatively describe the adherence behavior of different films on the same substrate. This improvement in the wear resistance for SiC-N films resulted from an increase in compressive residual stress. (C) 1997 Elsevier Science S.A.