OVER-RANGE BEHAVIOR OF SEALED-CAVITY POLYSILICON PRESSURE SENSORS

This paper reports the over-range behavior of sealed-cavity polysilicon pressure sensors with full-scale pressures ranging from 0.24 to 2.0 MPa (35 to 290 psi). Because of a built-in over-pressure stop, a fracture pressure between 24 and 41 MPa (3500 to 6000 psi) is observed, which is relatively insensitive to the particular size or range of the sensors investigated. Stress simulations using the finite-element method confirm this and provide a theoretical framework for designing over-range capabilities. Below the fracture range, no degradation in sensor performance is apparent after repetitive cycles of over-pressure to 21 MPa (3000 psi) and the zero repeatability is better than 0.1% of span. These results suggest outstanding over-range capabilities of sealed-cavity polysilicon sensors and exceptional mechanical strength and reproducibility of polysilicon diaphragms for pressure sensing.