Effect of deposition parameter on hardness of amorphous carbon film prepared by plasma immersion ion implantation using C2H2

Abstract

Carbon films were deposited on a cemented carbide substrate and silicon wafer at various bias voltages, acetylene (C2H2) pressures and process times by plasma immersion ion implantation (PIII). In order to investigate the substrate temperature, the tool steel substrate was also simultaneously treated. The final substrate temperature was estimated from the hardness of the tool steel substrate. The surface and cross-sectional morphology of the deposited films were observed using a scanning electron microscope (SEM). Depth profiles of the carbon were obtained by Auger electron spectroscopy (AES). Raman spectroscopy was employed for the structural evaluation of the films. The hardness of the deposited films was measured using a nano-indenter with the maximum load of 0.5mN.A variety of film hardnesses between 10 to 24GPa was obtained. The hardness of the carbon films decreased with the increasing bias voltage, C2H2 pressure and process time, although the intensity ratio of the disordered peak to graphitic peak in the Raman spectrum increased. It was considered that the decrease in the film hardness was caused by a stress reduction accompanied by a heating effect during the process as each PIII process parameter significantly influenced the substrate temperature.