Structure, hardness, and tribological properties of reactive magnetron sputtered chromium nitride films

Chromium nitride (CrN) films with Cr/N atomic ratios of 0.73-1.46 were prepared by reactive dc-magnetron sputtering with Ar as the sputtering gas and N-2 as the reactive gas. The application of a negative bias voltage to the substrates and the decrement of the gas flow ratio of N-2 to Ar (or F-N2/F-Ar) promoted the growth of CrN films with preferred orientations of (200) + (220), high Cr/N ratios, and high densities. The functional hardness and compressive stress were highly dependent on the magnitude of the bias voltage and the Cr/N ratio that was adjusted by the F-N2/F-Ar ratio during film deposition. The optimal energy conditions for ion impingement on growing CrN films with compact columnar crystal structure, high hardness, and enhanced tribological propel-ties were studied with respect to the modulations of the bias voltages and the Cr/N ratios. The CrN films with high hardness and high wear resistance were synthesized in this study at low bias voltages of -(100-300) V and F-N2/F-Ar ratios of 1-3. (C) 2000 American Vacuum Society. [S0734-2101(00)02701-9].