Nitrogen incorporation into titanium diboride films deposited by dc magnetron sputtering: Structural modifications

This work reports a study of titanium boron nitride (Ti–B–N) films deposited at room temperature by dc magnetron sputtering using a TiB2 target in different Ar–N2 gas mixture atmospheres. The influence of the nitrogen partial pressure on the structural, mechanical and tribological properties of these films has been studied. The films were analyzed by Rutherford backscattering spectrometry in order to determine their chemical composition and atomic density. X-ray diffraction (XRD) was used to probe the film microstructure and X-ray photoelectron spectroscopy (XPS) for the chemical characterization of the film surface. An atomic force microscope (AFM) was used to analyze the surface topography and, when operating in the lateral force mode, for the friction characterization of the films. The XPS results showed that the surface of the films deposited in pure argon atmosphere was composed essentially by Ti and B oxides, while TiB2, TiB, TiN and BN phases were present in the sputtered Ti–B–N films. Characterization by XRD determined the nanocrystalline nature of the films structure. While internal stress and friction increase upon the nitrogen incorporation, AFM measurements reveal a strong reduction of the surface roughness.