New approach to understanding the reactive magnetron sputtering of hard carbon nitride films

CNx films were deposited on Si(100) substrates at a substrate temperature of 600 degrees C using direct-current (DC) magnetron sputtering of a high-purity graphite target in pure nitrogen. The film characteristics were primarily controlled by the pressure, p (0.05 to 5 Pa), the discharge current on the magnetron target, I-m (0.5 to 3 A), and the radio-frequency (RF) induced negative substrate bias voltage, U-b (-300 to - 1200 V). The films, typically 1 to 2 mu m thick, were found to be amorphous, and they possessed an N/C atomic concentration ratio up to 0.35, hardness up to 40 GPa, elastic recovery up to 85%, good adhesion and promising tribological properties. A complex relationship between the process parameters and the film characteristics was investigated on the basis of correlations between the process parameters and the corresponding internal plasma parameters, such as ion bombardment characteristics and the densities of nitrogen atoms and CN radicals in front of the substrate. (C) 2000 Elsevier Science S.A. All rights reserved.