Preparation of Cr-Si multilayer structures for thin film heater applications

Multilayered thin film structures of Cr-Si have been prepared on top of Al2O3 substrates by RF magnetron sputtering technology, and the electrical and thermodynamic properties of the thin film structures were assessed up to the temperature of 500 °C. The thickness of the Cr-Si film was ranged to about 1 μm, and a post-annealing was carried out to achieve more reliable film structures. In measurements of temperature coefficient of resistance (TCR), chrome-rich films show the metallic properties, whereas silicon-rich films do the semiconductor properties. Optimal composition between chrome and silicon was obtained as 1:2 in the Auger electron spectroscopy analysis, and there is approximately 15% change or less of surface resistance from room temperature to 500 °C. Compared to the conventional heating elements, the thin film heater has additional advantages of extremely low outgassing and high ramping speed in addition to the temperature uniformity.