Test Methods for Fabrication of Automotive Micro Sensors

摘要

Efficient testing is of primary importance in the mass production of safety relevant but cost effective sensors required for automotive applications. The functioning of the sensor at the time of delivery as well as the reliability throughout its lifetime have to be guaranteed. This contribution focuses on sensors containing a sensor chip produced by micromechanical means. An economically viable approach is to test sensor chips on wafer level at an early stage of value adding. In order to predict the functional parameters of a sensor and to deduce wafer yield at this intermediate stage, the knowledge of multitude of geometrical and material specific parameters and their distribution across the wafer is required. The testing methods available today are not sufficient to obtain all the required parameters which hence calls for the development of innovative methods to fill the gaps. On the basis of two examples, pure electrical methods to determine material parameters like the thermal conductivity, the density or elastic constants at wafer level are demonstrated.