Growth, structure, and mechanical properties of CNxHy films deposited by dc magnetron sputtering in N2/Ar/H2 discharges

Hydrogenated carbon nitride films were deposited by reactive de magnetron sputtering in mixed Ar/N-2/H-2 discharges at temperatures of 100 and 350 degrees C. The total pressure was kept constant at 0.33 Pa and the gas mixtures were varied in order to study the effect of the hydrogen on the resulting film structure and properties. Chemical sputtering effects taking place during deposition were found to be an important factor for the growth and structural evolution. When H-2 is mixed into the discharge gas, the growth rate decreases considerably and the films become denser due to desorption of volatile species, like hydrocarbons, NH3 and HCN. For a H-2 fraction above 15%, no net film growth takes place. The hydrogen concentration incorporated into the films was highest (up to similar to 33 at. %) for low growth temperatures and low nitrogen concentrations. Furthermore, the results indicate that substantial amount of hydrogen are bonded to nitrogen. The incorporation of hydrogen in the structure interrupts the relatively long basal planes in graphite-like structures, and some regions transform into an amorphous structure. Nanoindentation measurements of the film showed decreased elasticity, as well as decreased hardness when,incorporating hydrogen. However, fullerene-like films grown at 350 degrees C in N-2/H-2 discharges exhibit high elasticity for H-2 partial pressures as high as similar to 10(-3) Pa due to low H incorporation into these films. (C) 2000 American Vacuum Society. [S0734-2101(00)03905-1].