High rate reactive sputtering of MoNx coatings

High rate reactive sputtering of MoNx films was performed using feedback control of the nitrogen partial pressure. Coatings were made at four different target powers: 2.5, 5.0, 7.5 and 10 kW. No hysteresis was observed in the nitrogen partial pressure vs. flow plot, as is typically seen for the Ti-N system. Four phases were determined by X-ray diffraction: molybdenum, Mo-N solid solution, β-Mo2N and γ-Mo2N. The hardness of the coatings depended upon composition, substrate bias, and target power. The phases present in the hardest films differed depending upon deposition parameters. For example, the β-Mo2N phase was hardest (load 25 gf) at 5.0 kW with a value of 3200 kgf mm-2, whereas the hardest coatings at 10 kW were the γ-Mo2N phase (3000 kgf mm-2). The deposition rate generally decreased with increasing nitrogen partial pressure, but there was a range of partial pressures where the rate was relatively constant. At a target power of 5.0 kW, for example, the deposition rates were 3300 A min-1 for a N2 partial pressure of 0.05-1.0 mTorr. (orig.)