Amorphous SiCx (x≤0.85) films thicker than 1μm were prepared by a magnetron-type reactive sputtering using a Si target and CH4 gas. Microhardness (Hv), internal stress and adhesion strength by the scratch test were measured. The microhardness of SiC0.85 films prepared by this technique was intrinsically determined to be 22GPa for 6μm-thick specimens. The microhardness for 1μm-thick SiCx films also showed a relatively small increase with the carbon content to that for 6μm-thick SiCx films. Compressive stresses (<3.2GPa) were observed in all SiCx films obtained in this work. The internal stress in the SiCx films (0.2μm thick) was well correlated with the crack length induced with a Vickers indenter as a result of the thin-layer surface stress analysis. The critical load of the SiCx films (1μm thick) decreased with increasing internal stress.
