An investigation into the use of a simple model for thickness uniformity on horizontal surfaces to describe thickness variations on vertical substrates

The present authors have previously demonstrated a model for the determination of the thickness uniformity on flat, horizontal plates which is easy to use because it only requires a small amount of measured data (a minimum of two known thickness and their location in the chamber). The model is based on an empirically observed inverse power law relationship between coating thickness and source-to-substrate distance and has been shown to be applicable both to surfaces of large substrates (i.e. facing both towards and away from the vapour source) and for a variety of deposition processes, including electron beam and sputtering based techniques. In the current paper we report further investigations into the model and its extension to incorporate coating thickness distributions on vertical surfaces, although at present shielding effects are not included in the model. The substrates used in this current work were mounted with the side facing the source being totally in its line of sight. The inclusion of thickness prediction on vertical as well as horizontal surfaces, however, enables the model to start to be of use in the determination of thicknesses on real components.