A Novel Pressure Microsensor With 30- μm-Thick Diaphragm and Meander-Shaped Piezoresistors Partially Distributed on High-Stress Bulk Silicon Region

A novel pressure microsensor is designed, fabricated and tested. Novel piezoresistive sensing structures using 30- mum thick silicon diaphragms (from 370 mum times 370 mum to 970 mum times 970 mum ) and meander-shaped piezoresistors are devised. The diaphragms in this work thicker than that of the conventional piezoresistive pressure sensors extend the high-stress distribution into the bulk silicon and improve the device reliability. Piezoresistors are partially fabricated on the high-stress bulk silicon to obtain high sensitivity and linearity. Effects of different diaphragm areas, piezoresistor shapes, and placing methods on the sensing performances are simulated, measured, and analyzed. The whole fabrication is low-cost and compatible with standard IC process. Measurement shows promising results, i.e., large test region (0-1 MPa), high sensitivity (70.4 mV/VldrFS ), small linearity error (0.012%/FS) and good precision (0.16%/FS). The work indicates a novel solution of small size, high-performance, high-reliability, and low-cost pressure microsensor for tire pressure monitoring system and many other applications.