Design of a Poly-SiGe Piezoresistive Pressure Sensor

Abstract

In this chapter, an extensive analysis, based on FE (Finite Element) simulations, on the structural design and optimisation of poly-SiGe based piezoresistive pressure sensors is presented. The considered pressure sensors consist of a deformable poly-SiGe membrane, fully clamped at its edges, and four poly-SiGe piezoresistors placed on top following a Wheatstone bridge configuration. Finite element simulations are used together with the experimentally obtained piezoresistive coefficients for poly-SiGe (Chap. 2) to optimize the sensor design parameters for enhanced sensitivity and linearity. The design parameters include the membrane area and shape and the location, shape and dimensions of the piezoresistors. The chapter begins by introducing the working principle of piezoresistive pressure sensors and their governing equations. The most important performance parameters for such sensors are also listed. The impact of the aforementioned design parameters on sensor performance is then evaluated, paying special attention to sensor sensitivity and linearity. Finally, two membrane shapes (square and rectangular), four membrane areas ($200\times 200$, $250\times 250$, $300\times 300$ and $350\times 175\,\upmu$ m$^{2}$) and six different piezoresistor designs are included in the layout (see Appendix A).