Study of ZrN layers deposited by reactive magnetron sputtering

Zirconium nitride films are deposited onto borosilicate wafers by reactive magnetron sputtering. The films are analysed in situ by X-ray photoelectron spectroscopy (XPS). We have studied by XPS the effects of the nitrogen partial pressure (1-100%), the subtract temperature (ambient to 450 degreesC), and biasing (0-80 W) on the stoichiometry of ZrN films. The N1s peak is composed of three components at 397.2, 396.4 and 395.8 eV in binding energy. These components are correlated with the three existing phases of zirconium nitride (ZrN, Zr3N4 and ZrN2). With an increase of the nitrogen partial pressure, a shift of the Zr3d line to the high binding energy and the increase of the N1s component at 395.8 eV are observed. These observations are explained by the charge transfer between Zr to N which increases with P(N-2) as previously described for the Ti-N-2 system [1]. The bulk stoichiometry is calculated by Rutherford backscattering and nuclear reaction measurements. The resistivity of the films is measured by the four-point probes technique. The reflectivity of the films are recorded by a spectrophotometer in the IR-Vis range. A correlation between the reflectivity and the resistivity is observed. The roughness of the films is measured by atomic force microscopy. The bias voltage has a great influence on the surface roughness and on the reflectivity of the films. The dependence of the ZrNx films structure and morphology with the discharge parameters is established. (C) 2003 Elsevier Science B.V. All rights reserved.