Full Silicon Capacitive Force Sensors with Low Temperature Drift and High Temperature Range

In this paper we present a concept for capacitive force sensors with a high operating temperature range and a low temperature drift. The sensors are completely fabricated out of silicon to ensure the absence of thermal stresses for a broad temperature range. The sensing capacitance is shielded by bulk silicon, which forms a Faraday cage against external static or quasi-static electrical interference around the electrodes. The sensors have a high sensitivity, since the capacitance changes by 100% at full scale (FS) load. First results show a high linearity and extremely low temperature drift of the base capacitance as well as a temperature drift of the sensitivity of only 0.006%FS /K at 300 °C without additional compensation.