A Piezoresistive Mems Barometer with Thermomecanical Stress Rejection

We report and experimentally validate a new technology process flow for a barometer with onchip springs for thermomechanical stress rejection. This innovative micromachining process has been implemented in monocrystalline silicon wafers to ensure the large sensitivity by forming first a bulk thick membrane, which holds a thin pressure sensing membrane. Measurements of the absolute accuracy drift over temperature of soldered devices and of the performance under 4-points PCB bending show a superior performance compared to state of art glue-stacked MEMS barometers. By moving the package complexity inside the MEMS die, the proposed structure, applicable to other sensors (e.g. humidity, accelerometers), enables cost-effective compact fully-molded packaging.