Accurate simulation of high-performance silicon pressure sensors

A simulation program is described which is capable of accurately calculating the output response of silicon piezoresistive and capacitive pressure sensors as a function of both pressure and temperature. A thermoelastic plane-stress formulation is used in calculating the stress and deflection of the transducer diaphragm. Diaphragm thickness taper, oxide and package stress, and rim effects are simulated. The simulations are compared with experimental results for several structures of interest. For capacitive structures, stepped diaphragm profiles are shown to be capable of improving the pressure sensitivity by as much as fifty percent. The package-induced thermal drift for electrostatically-sealed glass-silicon devices is typically less than 0.05 mmHg/°C.