Comparative investigation of Ti–Si–N films magnetron sputtered using Ti 5Si 3+Ti and Ti 5Si 3+TiN targets

Abstract

A comparative investigation of Ti–Si–N films deposited by DC magnetron sputtering (MS) of composite Ti 5Si 3+Ti and Ti 5Si 3+TiN targets in an argon atmosphere or reactively (RMS) in a gaseous mixture of Ar+N 2 is presented. The targets were manufactured by means of self-propagating high-temperature synthesis. The microstructure, phase and chemical composition of Ti–Si–N films were studied by means of X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Auger electron spectroscopy. The films were characterized in terms of their hardness, elastic modulus, elastic recovery and surface topography. Measurements of hardness were performed by the method of sclerometry (hardness under failure) and by load–depth-sensing nanoindentation (hardness under elastic and plastic deformation). The friction coefficient of Ti–Si–N films against hard metal was also determined. Results obtained show that the Ti–Si–N films deposited in pure Ar using Ti 5Si 3+TiN target consist of nanocrystalline TiN in an amorphous a-TiSi x matrix. The volume fraction of the fcc phase increased as the substrate temperature or bias voltage was raised. The films deposited by sputtering of Ti 5Si 3+TiN target in Ar and by sputtering of Ti 5Si 3+Ti target in Ar+14% N 2 were characterized by the presence of planar (100) texture. This preferred orientation, however, becomes less pronounced as the nitrogen partial pressure is raised up to 14% and 24%, respectively. The Ti–Si–N films consist of crystalline grains, 2–15 nm in size, elongated in the direction of film growth. When N 2 was added to the gas discharge during deposition, the TiN grain size slightly increased. The lattice parameter was calculated from X-ray diffraction spectra to a≅0.431–0.432 nm (MS) and a≅0.428–0.430 nm (RMS) that is higher than that of the bulk TiN (0.424 nm). The films showed hardness less than 35 GPa and Young's modulus in the range of 220–250 GPa. Friction coefficient values between approximately 0.5 and 0.6 were recorded.