Effects of pulse bias on structure and properties of silicon/nitrogen-incorporated diamond-like carbon films prepared by plasma-enhanced chemical vapor deposition

We have deposited silicon/nitrogen-incorporated diamond-like carbon (Si–N-DLC) films by radio-frequency plasma-enhanced chemical vapor deposition using methane (CH4), argon (Ar), and hexamethyldisilazane {[(CH3)3Si]2NH} as the Si and N source, and investigated the structure and mechanical and tribological properties of the films. We compared the Si–N-DLC films deposited using pulse bias applied to a silicon substrate with those prepared using dc bias. As the Si and N fractions in the films increased, the internal stress of the films decreases and the adhesion strength to the substrate increased. It was found that the use of the pulse bias was effective in suppressing the formation of particles and further increasing the adhesion strength. The Si–N-DLC films had as low a friction coefficient as Si-incorporated DLC films in ambient air, and the friction coefficients of the films prepared with the pulse bias were lower than the dc-biased films. In addition, the pulse-biased films had a higher wear resistance than the dc-biased films.