Optimum design considerations for silicon piezoresistive pressure sensors

Abstract

Optimum design considerations for silicon piezoresistive pressure sensors are carried out on the basis of the design restriction release produced by recent progress in microwave plasma etching technology. The optimum shape and plane of a diaphragm and the optimum direction of gauges are analysed by taking into account the effects of anisotropy of the piezoresistivity and elasticity and large deflection of diaphragms. A new index η, which expresses the relative performance of sensors, is introduced for the optimal gauge direction on the optimal diaphragm plane. It is found that the optimum design is as follows: four gauges are aligned on a 〈111〉 direction on a {110} plane square diaphragm with a centre boss.