Control of the thickness distribution of evaporated functional electroceramic NTC thermistor thin films

In this work the thickness distribution of NTC thermistor thin films produced by low deposition rate (0.8 nm s−1) electron-beam evaporation is investigated. The target preparation, deposition conditions and geometrical set-up of the evaporation mechanism are described in detail. The evaporation geometry is shown to be critical for the thickness distribution of evaporated films. The film thickness distribution of evaporated layers was measured across a macroscopic film surface using Alpha Step stylus profileometer. The thickness distribution was fitted using a geometrical model derived from evaporation theory, based on the Hertz–Knudsen equation and a modified version of the cosine law of emission. From this model, the sticking coefficient of the vapour on the substrates could be estimated to be 80 ± 1.5%.