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S. Fricke, A. Friedberger, G. Müller, W. Brode, H. Seidel, U. Schmid:
"Electrical Performance of Alumina Thin Films for High-Temperature Pressure Cells With a Metallic Body";
IEEE Sensors Journal, 10 (2010), 5; 918 - 923.

Sputter deposited alumina thin films were investigated
with regard to their performance as high-temperature
electrical insulators. A target application of such dielectric films
is in metal pressure sensor cells intended for high-temperature
operation. The leakage behavior of sputtered alumina films was
investigated by analyzing the temperature-dependence of the I-V
characteristics of alumina films deposited on silicon and Haynes
230 substrates. Silicon substrates were used to analyze the leakage
behavior under optimally controlled substrate conditions. Haynes
230, a nickel-based superalloy, was used as a substrate material
to simulate conditions expected in a high-temperature metal pressure
cell. In order to compare the dielectric performance under
conditions of closely similar substrate quality, the topography of
the Haynes 230 substrates was improved by applying a lapping
process. From our results, we derive an estimate of the maximum
operating temperature of metal pressure sensor cells.

Al2O3, alumina, harsh environment, high temperature, metallic, pressure, sensor, sputter deposition, superalloy, thin-film.