In this paper, we present an innovative manufacturing process for the production of capacitive pressure and force sensors with excellent thermal stability for high-temperature applications. The sensors, which are manufactured from a stack of two silicon chips mounted via with gold–silicon (Au-Si) or aluminum–silicon (Al-Si) eutectic bonding, are shielded, miniaturized, and allow an operating temperature of up to 500 °C. Compared to conventional methods, the greatest benefit of the manufacturing process is that different sensor dimensions can be produced in the same batch for a wide measuring range, from mN to kN. The characterization of the realized sensors shows a high linearity and a low temperature drift of 99.992% FS and −0.001% FS/K at 350 °C, as well as a nonlinearity of 0.035% FS and a temperature drift of −0.0027% FS/K at 500 °C.

This paper demonstrates a shielded capacitive force and pressure sensor that can operate at 500 °C. The measurements show a high accuracy of the sensor with an excellent thermal stability of only −0.0027 %/K full scale (FS) and a nonlinearity error of the inverse capacitance of 0.035 %FS at 500 °C without any additional compensation. A significantly high temperature and mechanical stability was realized by a novel process using Aluminum-Silicon (Al-Si) eutectic bonding. This has the advantage of increasing the operating temperature up to 500 °C without appreciable loss of accuracy and sensitivity compared to standard Gold-Silicon eutectic bond [1]. A Si-Al/Al-Si stack has been investigated and we reveal that the eutectic temperature of 577 °C specified in the Al-Si phase diagram is not sufficient. The best results were obtained at 650 °C and beyond under vacuum condition.