Properties of zirconium oxide thin films deposited by pulsed reactive magnetron sputtering

Zirconium oxide thin films were deposited by direct current (d.c.) reactive magnetron sputtering on glass slide, silicon wafer and stainless steel substrates. The thickness of the thin films was between 200 nm and 3 mu m. The target power density controlled deposition process was used. The process parameters investigated were the target power, the sputtering gas pressure and the substrate bias voltage and their influence was studied on the film properties such as O/Zr ratio, density, nanohardness, intrinsic stress, crystallographic structure and surface roughness. The deposition rate increased as a function of the target power, the sputtering gas pressure and the substrate bias voltage. The nature of the residual stress changed from compressive to tensile as the sputtering gas pressure was increased. The nanohardness of the thin films increased with decreasing sputtering gas pressure and with increasing substrate bias voltage. The thin films were colourless and transparent when fully oxidised to monoclinic structure, black when rich in metal. These black substoichiometric thin films with the O/Zr ratio of 1.6 had a tetragonal structure. Black thin films represented low nanohardness and strongly increased surface roughness. (C) 1999 Elsevier Science S.A. All rights reserved.