Abstract
Based on the optimum deposition conditions of ZrN thin film from our previous study, by varying oxygen flow rate ranging from 0 to 8 sccm, nanocrystalline ZrN x O y thin films were deposited on p-type (100) Si substrates using hollow cathode discharge ion-plating (HCD-IP) system. The objective of this study was to investigate the effect of oxygen content on the composition, structure and properties of the ZrN x O y thin films. The oxygen content of the thin film, determined using X-ray photoelectron spectroscopy (XPS), increased with increasing oxygen flow rate. As the oxygen content increased, the color of the ZrN x O y thin film changed from golden yellow to blue and then slate blue, and the microstructure observed by scanning electron microscopy (SEM) varied from columnar structure to finer grains and finally flat and featureless structure. Phase separation of ZrN x O y to ZrN and monoclinic ZrO 2 was found from X-ray diffraction (XRD) patterns when the oxygen content was higher than 9.7 at.%. The hardness of the film slightly increased as the oxygen content was less than 9.7% and then decreased to 15.7 GPa, a typical hardness of ZrO 2 phase, as the oxygen content further increased. The total residual stress of the film was measured using an optical method, and the residual stresses of ZrN and ZrO 2 phases were determined separately using modified XRD sin 2 ψ method. The total stress was close to the stress in ZrN phase as the ZrO 2 fraction was less than 30%, and was close to that in ZrO 2 phase as the ZrO 2 fraction was over 30%. The electrical resistivity of the film increased significantly with the increase of oxygen content. The film properties showed consistent trend with phase separation. As the fraction of ZrO 2 phase was small, the apparent properties of the films were more close to those in ZrN. When ZrO 2 fraction was over 30%, the films mainly exhibited the properties of ZrO 2 . © 2006 Elsevier B.V. All rights reserved.