Plasma oxidation of bilayered Y/Zr films

The two-layered Y/Zr structures (0.1 mu m thick of Y film on 1.0 mu m thick of Zr film) have been deposited on silicon substrate and oxidized in Ar+O-2 plasma in temperature range 350-800 degrees C simultaneously under irradiation by ions extracted by 100 V bias. The characterization of coating structure was carried out by the X-ray diffraction, The secondary ion mass-spectrometry was used for the recording of depth profiles of the most important elements in film and at interface. The surface topography was monitored by atomic force and scanning electron microscopes. It is shown that the oxidation kinetics in complex way depends on parameters of irradiation and temperature. The homogeneous nanocrystalline YSZ films have been obtained after plasma oxidation for temperatures higher than 450 degrees C and ion current density 1 ma.cm(-2). The atomic mixing and oxidation mechanisms are discussed. The emphasis is made on the analysis of surface instabilities acting as possible driving force for the intermixing and restructuring of Y/Zr layers. (c) 2008 Elsevier B.V. All rights reserved.