Correlation between SiOx content and properties of DLC:SiOx films prepared by PECVD

Hard diamond-like carbon (DLC) films with an addition of SiOx were deposited in capacitively coupled r.f. discharges from a mixture of methane and hexamethyldisiloxane (HMDSO). The flow rate of HMDSO was changed in order to vary the SiOx content in the films. Complete atomic composition of the films was determined by Rutherford backscattering spectroscopy combined with elastic recoil detection analysis. The thickness and the optical properties were obtained from the ellipsometric measurements. The mechanical properties were studied by a depth sensing indentation technique using Fischerscope H100 tester. The O/Si ratio in DLC:SiOx films was 0.286±0.008 and the content of SiOx increased with the HMDSO-to-methane flow rate ratio q. The DLC:SiOx films were close to DLC films as concerning the optical properties in the UV/visible and the high hardness if q was maximum 0.25. However, the compressive stress in the films was reduced, the film fracture toughness was improved and the deposition rate increased.