Properties of carbon nitride films deposited by magnetron sputtering

Carbon nitride films have been deposited by r.f. and d.c. planar balanced magnetron sputtering under various conditions. The films were analysed by Rutherford back-scattering (RBS), electron energy loss spectroscopy (EELS), and Fourier transform infrared (FTIR) spectroscopy. The deposition rates of the films synthesised by r.f. magnetron sputtering increased with nitrogen content in the sputtering gas. The nitrogen content of the films also increased as the nitrogen content in the sputtering gas was increased to 50 vol.%, and then remained constant. Absorption bands at 1250, 1550 and 2200 cm−1 were detected in FTIR spectra, corresponding to Raman-reactive disordered sp2 carbon, graphite-like sp2 carbon, and nitrile or isocyanate groups, respectively. Additionally, broad absorption around 1000–1200 cm−1, which may be associated with sp3 hybridised carbon, was observed in films deposited with low nitrogen content in the sputtering gas. Sputtering gas total pressure and sputtering power were also varied. The results were interpreted in terms of the collision frequency of the sputtered species with reactive gases in the system. The films deposited with >70% nitrogen in the sputtering gas showed higher friction coefficients and lower wear resistance in sliding friction tests than films grown with lower gas nitrogen content, suggesting that these properties of the films were associated with their structure.