A monolithic fully-integrated vacuum-sealed CMOS pressure sensor

Abstract

This paper presents an integrated multitransducer capacitive barometric pressure sensor that is vacuum-sealed at wafer level. The interface circuitry is integrated directly within the sealed reference cavity, making the device immune to parasitic environmental effects. The overall device process merges BiCMOS circuitry with a dissolved wafer transducer process, is compatible with bulk- and surface-micromachining, and employs chemical mechanical polishing (CMP), anodic bonding, and hermetic lead transfers. The sensor achieves 15b resolution and is suitable for low-cost packaging. The device is composed of a programmable switched capacitor readout circuit, five segmented-range pressure transducers, and a reference capacitor, all integrated on a 7.5/spl times/6.5 mm/sup 2/ die using 3 /spl mu/m features.