Application of finite element models for design of high-precision MEMS pressure sensors

Abstract

Finite element models of piezoresistive silicon pressure sensor with dielectric isolation as well as resonant pressure sensor (RPS) and optomechanical unit of photoelectric fiber-optical pressure sensor are presented in this paper. The models take into account various specific effects which are taking place while designing sensors with an overall error less than 0.5% with only passive elements. That type of sensors has a great interest for applications with a harsh environment conditions (high operation temperature and so on). It is demonstrated, that consideration of scaling effects for piezoresistive pressure sensors allows to increase sensor sensitivity and to compensate both full scale span and zero offset temperature dependence. Also the calculations of the RPS sensitivity with an actual shape of resonator and its junction region to elastic element are presented in this paper. A dependence of the pressure sensor resonant frequency on technological factors is established. It is shown, that a rational choice of optomechanical unit construction of photoelectric fiber-optical pressure sensor allows to gain 20% increase in amount of movement of optical fiber and, as a result, to increase sensitivity. An efficiency of finite element models is demonstrated on the existing pressure sensors samples.