Measurement of residual stress in DLC films prepared by plasma-based ion implantation and deposition

A hybrid process of plasma-based ion implantation and deposition (PBIID) was used to achieve relaxation of compressive residual stress in diamond-like carbon (DLC) films. The residual stress in each film was determined from the curvature of quartz glass plate using Stoneyʹs equation. The compressive residual stress in the DLC film prepared using acetylene gas was about 0.46 GPa without the negative pulsed voltage for ion implantation. The residual stress decreased considerably with the increase of the negative pulsed voltage during deposition and reduced to about 0.16 GPa at the negative pulsed voltage of −20 kV. The residual compressive stress in the DLC films prepared using toluene gas was reduced to about several MPa at the region of negative pulsed voltage of −5 to −7 kV. These reduction of stress might be due to the thermal spike effect by ion implantation. However, at the negative pulsed voltage exceeding about −10 kV, the reduction of residual stress was not observed because of generation of glow discharge by the negative pulsed voltage. In either case, the observed residual stress of the DLC film was almost two orders less than that of conventional DLC films.