Significance of controlling key process parameters during dlc deposition using rf plasma-enhanced cvd

Diamond-like carbon (DLC) films have been deposited on silicon substrates using a custom built chemical vapor deposition (CVD). The films were found to be ≤1 μm in thickness and generally amorphous in nature. The radio-frequency (RF) power was found to be a critical process parameter, which influenced the film properties, such as hardness, surface roughness, morphology and adhesion. As the RF power is increased changes take place within the plasma such as the self bias voltage, which becomes more negative with increasing RF power at low pressure. Deposition rates and film surface roughness values were found to be dependent on the RF power used during deposition of DLC. As expected the as grown films became more porous as the self-bias voltage became more negative. This could be due to the occurrence of enhanced ion bombardment at the film surface during deposition. Indentation tests coupled with acoustic emission showed that on increasing the RF input power form 100 W to 250 W, the critical load changed gradually from 8N to 3N, indicating a decrease in the coating adhesion. (author)