Composition and formation mechanism of zirconium oxynitride films produced by reactive direct current magnetron sputtering

Direct current magnetron sputtered zirconium oxynitride films show an improvement in both deposition rate and physical properties compared to zirconium oxide. Here we seek to understand these beneficial effects and report on the film composition and crystallographic structure. Based on a thermochemical description together with a modeling of formation kinetics we propose a film formation mechanism, which explains many of the observations. Rutherford backscattering spectroscopy (RBS) shows early nitrogen incorporation at 64% N2 flow in disagreement with the predictions of thermochemistry. The stoichiometry is only successfully simulated with the use of an expanded Berg–Larsson model with a low replacement coefficient of about 0.1 of nitrogen by oxygen after metal‐nitrogen bond formation. The deviation from complete replacement as predicted by thermodynamics illustrates the importance of kinetics in film formation. The model further successfully predicts the variation of the mass deposition rate. The X‐ray diffraction analyses suggest that, within the crystalline phase, nitrogen atoms occupy oxygen sites, resulting in an unchanged zirconium oxide structure. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)