Contact pressure measurement using silicon-based AlxGa1−xAs semiconductor pressure sensors

Various types of pressure sensors are widely used in manufacturing, defence, medical and precision industries. Most of these sensors are based on either piezoelectric or piezoresistive mechanism for sensing applications. Piezoelectric pressure sensors are not suited for measuring static pressure mainly due to leakage of electric charges under constant pressure. Surface micromachined silicon pressure sensors, based on piezoresistive mechanism, are reliable with satisfactory pressure sensitivity. However, the use of mechanical diaphragm limits the performance of the sensor due to its slow response time when a pressure is applied. The measurable pressure by silicon pressure sensor is also low (mostly in kPa range) and is not suitable for high contact pressure measurement (MPa in range). This paper reports the fabrication and testing of pressure sensitive silicon-based AlxGa1−xAs pressure sensors, which are suitable for both static and dynamic pressure measurements with a wide range of applied pressure. The pressure sensors are fabricated based on two different kinds of substrates, silicon and GaAs, and tested under various conditions. Contact pressure sensitivity, linearity, hydrostatic pressure sensitivity, hysteresis, temperature sensitivity and long-time stability (creep) test results for these two types of the fabricated pressure sensors have been compared and presented in this paper.