Design and modeling of an electromagnetically excited silicon nitride beam resonant pressure sensor

An electromagnetically excited silicon nitride beam resonant pressure sensor is described and numerical modeling is carried out on the analysis of the sensitivity of pressure measurement and temperature drift. The proposed approach is based on measurement of resonant frequencies for two resonant beams located on a diaphragm inducing different axial stress under an applied pressure, the differential output of which provides the pressure reading of the sensor. The frequency drift induced on both beams due to ambient temperature influence will be the same, guaranteeing a temperature independent pressure sensing. The device is fabricated in one piece from single crystal silicon by MEMS technology and silicon-rich SiN beams are released by undercutting in KOH etching solution. Both simulation and experimental results show that the proposed method improves the sensitivity, linearity, and temperature stability.