Hydrogen Effects on the Properties of Silicon/Nitrogen-Coincorporated Diamond-Like Carbon Films Prepared by Plasma-Enhanced Chemical Vapor Deposition

Abstract

We have deposited silicon/nitrogen-coincorporated diamond-like carbon (Si–N–DLC) films by radio-frequency plasma-enhanced chemical vapor deposition using hexamethyldisilazane (HMDS) as the Si and N source, and investigated the structure, chemical bonding, and the mechanical and tribological properties of the films. We compared the properties between Si–N–DLC films deposited with hydrogen gas and those with argon gas, which were used as the dilution gases. As HMDS flow ratio [HMDS/(HMDS+CH 4 )] increased, internal stress decreased and, at the same time, adhesion strength determined by scratch tests increased. However, many particles were observed on the film surfaces when the deposition with argon gas was carried out. It was found that the use of hydrogen gas was effective in suppressing the formation of particles and further increasing adhesion strength. Friction coefficient, as evaluated by ball-on-plate reciprocating friction tests, decreased with increasing HMDS flow ratio. The friction coefficient values of the Si–N–DLC films were as low as those of Si-incorporated DLC films. We also found that employing hydrogen gas reduced the friction coefficient and wear rate of the films.