Titanium and titanium nitride thin films grown by dc reactive magnetron sputtering Physical Vapor Deposition in a continuous mode on stainless steel wires: Chemical, morphological and structural investigations

Ti and TiN thin films (50-140 nm thick) are grown by dc reactive magnetron sputtering PVD in an inverted cylindrical magnetron (ICM) thanks to an original industrial process corresponding to a continuous reactive deposition on moving stainless steel wires. Thin films are fully characterized by X-ray Photoelectron Spectroscopy, Transmission Electron Microscopy coupled with Energy Dispersive Spectroscopy and Orientation Phase Mapping. The stoichiometry of TiN is adjusted thanks to N2 flow. At the beginning of poisoned mode, golden stoichiometric TiN thin films are obtained. In the metallic mode, greyish TiNx films are grown whereas at higher N2 flow, TiNxOy films are synthetized with preferential O incorporation instead of N enrichment. Grain orientation maps reveal that Ti and TiN thin films are highly polycrystalline: Ti films have an equiaxis morphology whereas TiN thin films have a tendency to present 〈111〉 columnar grains with 〈001〉 oriented grains at the nucleation step. Finally, a low temperature of growth (of about 350 °C and < 650 °C) is needed in order to prevent chemical diffusion from the stainless steel substrate into the rich-titanium films.