Correlation between structure and hardness of magnetron sputtering deposited CN_x films

Carbon nitride films are deposited on Si (001) substrates by reactive dc magnetron sputtering graphite in a pure N2discharge. The structure of carbon nitride films has been probed using Fourier transformation infrared, near edge X-ray absorption fine structure (NEXAFS) and high resolution electron microscopy (HREM), and the hardness has been evaluated in nanoin-dentation experiments. FTIR spectra show that N atoms are bound to sp1, sp2, and sp3 hybridized C atoms. Cls NEXAFS spectra show that the intensity of π resonance is the lowest for the film grown at substrate temperatureT s = 350°C, with a turbostratic-like structure and high hardness, while it is the highest for the film grown atT s = 100°C, with an amorphous structure and low hardness. The correlation between the structure and hardness of carbon nitride films has been discussed.