MAGNETRON-SPUTTERED CARBON NITRIDE FILMS

Carbon nitride (CNx) thin film deposition was undertaken in a closed-field, unbalanced magnetron system. Reactive deposition utilised a graphite target in an argon/nitrogen plasma. The main deposition parameters investigated were magnetron current, total gas pressure and nitrogen gas partial pressure. The films deposited were examined using IR spectroscopy, ellipsometry, and X-ray diffraction (XRD). Analysis of the results yielded the following characteristics: refractive index of nitrogen-containing films was reduced below that for pure carbon films but had little dependence on substrate bias and total gas pressure. It was, however, strongly dependent on the magnetron current at which the film was deposited. IR spectroscopy showed the transmittance of the films for given deposition conditions to be a monotonic function of nitrogen content. The deposition conditions themselves also had a significant effect, in particular the magnetron current. In addition, C=N bonding was evident from the absorption bands observed. Structural analysis by means of XRD showed that the amorphous nature of the films with some degree of graphitic content depended more on the deposition parameters than on the nitrogen concentration. Increased graphitic-type structure was observed at low magnetron currents, high system pressure and large (negative) substrate bias.