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 o f 600 degrees C using direct-current (DC) magnetron sputtering of a high-pu rity graphite target in pure nitrogen. The film characteristics were primar ily 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) induce d negative substrate bias voltage, U-b (-300 to - 1200 V). The films, typic ally 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 re covery up to 85%, good adhesion and promising tribological properties. A co mplex relationship between the process parameters and the film characterist ics was investigated on the basis of correlations between the process param eters and the corresponding internal plasma parameters, such as ion bombard ment characteristics and the densities of nitrogen atoms and CN radicals in front of the substrate. (C) 2000 Elsevier Science S.A. All rights reserved .