Silicon capacitive pressure sensors and pressure switches fabricated using silicon fusion bonding

摘要

A simple single crystal silicon process for fabricating capacitive type pressure sensors and pressure switches is described. The process relies on silicon fusion bonding for the sealing of the pressure sensor cavity sod device construction. The pressure sensor cavity is etched in a thick oxide, thus allowing freedom in cavity design. Pressure sensors and pressure switches have successfully been fabricated using this process. Results are presented of a capacitive type element operating in the medical pressure regime (0-300mmHg) with a sensitivity to pressure of 1.5 fF/mmHg or 305 ppm/mmHg, and of a pressure switch operating at 5 bar for use in truck tyres.