Effect of air annealing on mechanical properties and structure of SiCxNy magnetron sputtered films

The hardness of the as-deposited films decreases with the growth of N2/Ar flow ratio. Air annealing at 700 °C leads to atomic short-range ordering in the amorphous SiCxNy films that significantly increases their hardness and elastic modulus at all used loads (10-100 mN). The hardness of the SiCxNy films annealed in air at 900 °C reduces when measured at low indenter loads (10-20 mN) due to onset of top layer oxidation. Hardness of inner layers, measured at 50-100 mN loads, increases approaching values exhibited by the vacuum annealed films. Air annealing at 1100 °C leads to intensive surface oxidation and formation of graphite-like structure in carbon clusters of inner layers. The hardness and oxidation resistance of the investigated SiCxNy films reduce with the increase of N2/Ar ratio.