An investigation into the thickness and coating structure uniformity of zirconia films on flat surfaces

The authors have previously demonstrated a model for the determination of the thickness uniformity on flat, horizontal plates, which is based upon an empirically observed inverse power law relationship between the coating thickness and the source-to-substrate distance. The model is simple to use because it only requires a small number of measured data, provided that the locations are accurately known relative to the source. This paper employs zirconia-based coatings, deposited using electron-beam-based deposition techniques, onto large substrates, to provide further confirmation for the use of the above model. Of particular interest was the effect on the thickness distribution that resulted from scanning the beam during operation rather than letting it remain stationary. In addition, because the relative intensities of the evaporant flux and the sputter bombardment from the plasma will vary across the plate, it might be expected that the structure of the coating may also change across the substrate, so this effect is also studied. Zirconia was selected for this work because, since the coatings are relatively thick, it is possible to observe changes caused in the structure as a consequence of the changing ratio of evaporation flux arrival: sputter removal that results from ion bombardment.