Diagnostic measurements and modelling of an ion-based PVD-process with high deposition rates

Abstract

Abstract The controlled plasma-PVD deposition of metal ions provides a tool to deposit metal coatings or interlayers of high quality. Another advantage is the possibility to confine the depositing ionic species by using externally applied magnetic fields. Using adequate field configurations, very homogeneous films can be grown on large substrates. A critical issue to be solved in such ion-based deposition processes is to efficiently ionize large fluxes of metal atoms and transport the ions to the substrate. In the PVD-process described in this paper, a flux of neutral metal atoms (Al) was produced by evaporation from an effusion cell or, alternatively, by magnetron sputtering. The Al atoms entered a dense, magnetically confined plasma of k T e =10 eV and n e =10 11 –10 12 cm −3 which served as a source to ionize the Al-neutrals. Subsequently the Al + -ions were guided along a magnetic field to the substrate. In order to understand and to optimize these process, experimental measurements and numerical analyses were carried out. Electric probes were used to determine local plasma parameters and quantitative optical emission spectroscopy (OES) measurements gave information on the local neutral Al-atom and of the Al + -ion population. After the experiments the deposition rate was derived from weight gain and film thickness measurements. These results were compared with a numerical model of the plasma based processes. Good agreement was found for the measured and calculated Al-population in the plasma and also for the measured and calculated film growth rates.