SINGLE-CRYSTAL SILICON PRESSURE SENSORS WITH 500X OVERPRESSURE PROTECTION

Single-crystal silicon piezoresistive pressure sensors with high overpressure tolerance have been fabricated using the process of silicon fusion bonding. A mechanical stopping surface beneath a conventional diaphragm structure limits diaphragm displacement during overpressure conditions. Uniform and bossed diaphragms in gage and absolute configurations are possible using this process. Sensors with sensitivities as high as 3 mV/ V/psi (typical of sensors used for 5-10 psi full-scale applications) survived overpressures of up to 5000 psi. Finite element modeling is compared to experimental results. © 1990.