Combination of Different Methods to Characterize Micromechanical Sensors

Abstract

ABSTRACTIn the last years many micromachined sensors for measuring quite different quantities have been developed (e.g. [1][2]). The successful design of silicon micromachined sensors and their conversion into commercial products is still limited by the lack of full understanding of complex fault mechanisms. In order to detect those mechanisms it seems to be advantageous to investigate interrelated phenomena by different analysis methods. By combining results of several means the true nature of disturbing effects can be determined much more easily.This paper describes a comprehensive approach for investigating failure mechanisms in piezoresistive pressure sensors. Sophisticated methods of signal analysis were combined with special semiconductor techniques, determination of thermo-mechanical properties, Finite-Element- (FE-) simulation and Michelson interferometry. By that it was possible to separate disturbing mechanical as well as electrical effects and their relation to sensor output and sensor accuracy, respectively. In particular, we discovered complex influences of passivation layer systems (differing in geometrical and technological parameters) on sensor accuracy.