Amorphous silicon carbonitride [Si(C,N)] thin films were prepared on glass and silicon substrates by plasma-enhanced chemical vapor deposition using hexamethyldisilazane and nitrogen, with hydrogen as the carrier gas. These films were studied by controlling the substrate temperature, radio frequency (r.f.) discharge power, and how rates of H-2 and N-2. A variation in the heat of adsorption with r.f. power was identified. The films were characterized by electron spectroscopy for chemical analysis and scanning electron microscopy for morphology. Mechanical properties such as hardness, scratch adhesion, and internal stress were also evaluated on the as-deposited films. Growth rate increased with r.f. power but decreased with substrate temperature. Hardness changed with experimental parameters and varied in the range 12-18 GPa. Scratch tests displayed a good adhesion between the film and substrate. Internal stress of the thin films had a different dependence on r.f. power for films deposited at 350 and 450 degreesC.