CMOS-based high-Pressure sensor using surface trenches for sensitivity enhancement

This paper reports on the development and characterization of a novel CMOS-based, low-cost, high-pressure sensor with inherent overload protection. The sensor consists of an anodically bonded silicon-Pyrex stack with surface trenches micromachined into the CMOS substrate. Due to the difference in elastic moduli of silicon and Pyrex, an applied hydrostatic pressure causes an anisotropic stress distribution in the chip area between the trenches. The induced stress is measured using n-doped piezoresistors arranged in a Wheatstone bridge configuration placed between the trenches. Pressure sensors of this type realized using an industrial 0.45-μm CMOS process in combination with post-CMOS processing have been characterized up to 60 bar and show a sensitivity of 44.1 μV/V/bar.