Silicon carbide diode bridge circuit for capacitive sensor readout in high temperature (673K) environmnet

Sensing using a micro-device at high temperature is a critical problem as a Si readout circuit does not work at high temperature, even if a sensor itself is heat-resistive. We for the first time proposed and demonstrated a SiC diode bridge circuit for capacitive sensor readout at high temperature. SiC pn-junction diodes were tested at high temperature up to 673 K. The SiC diode circuit was constructed on a sapphire substrate with Ni wedge wire bonding and die attach using high temperature conductive paste. The concept was demonstrated using a MOS capacitor bank as a dummy sensor, and differential capacitance was successfully read at 673 K.