Integration von galvanisch realisierten Sensorstrukturen auf mikroelektronischen CMOS-Schaltungen

Abstract

This dissertation describes the development of a sensor for measuring acceleration-thresholds in the low-g-range. The unusual characteristic of this sensor consists of the feature to fabricate the sensor on top of a CMOS signal processing circuit. In this context, the additive electroplating technology combines the advantages of monolithic- and hybrid-integrated sensors with respect to the reduction of interconnections, short development cycles, low tooling costs, and high design flexibility. A detailed technical concept for the fabrication of electroplated micromechanical acceleration switches is presented in this work. It comprises the aspects of the interface technology between the ASIC and the sensor structure, the sensor fabrication and the back-end processing to capsulate the dies. The microswitches are fabricated using microforms, which are moulded by an electroplating process, thus resulting in laterally moveable metallic microstructures. Therefore a low temperature ! dry process was developed to remove the sacrificial resist layer in order to eliminate the dangers of stiction. Other technological improvements were done to increase the yield of the processflow. Therefore optimised technologies considering the electroplating process and the coating of the electrical contacts have been developed. The developed packaging technology enables the hermetic sealing of these micromechanical structures and provides a mechanical overload protection. The additive electroplating technology offers an new fabrication method for a variety of further devices such as coils, interdigitated electrodes, springs and others structures which can be used in various different applications. The switch devices fabricated with this technology were tested extensively and showed very good performance characteristics.