Compensated semiconductor pressure sensor

Abstract

A semiconductor pressure sensor compatible with fluid and gaseous media applications is described. The semiconductor pressure sensor includes a sensor capsule having a semiconductor die and a silicon cap that is bonded to the semiconductor die. The semiconductor die includes a diaphragm that incorporates piezoresistive sensors thereon, and a stress isolation mechanism for isolating the diaphragm from packaging and mounting stresses. The silicon cap includes a cavity for allowing the diaphragm to deflect. The semiconductor pressure sensor further includes a pressure port that is hermetically attached to the semiconductor die. The sensor capsule and pressure port may be incorporated into a plastic housing. In one embodiment, the silicon cap is bonded to the semiconductor die to form an integral pressure reference. In an alternative embodiment, a second pressure port is provided for allowing gage or differential pressure measurements. A technique for incorporating the piezoresistive sensors is also described. An ASIC may be optionally attached to the silicon cap, and/or active electronic circuitry may be fabricated on the semiconductor die or silicon cap. Additional coatings may be optionally applied to the pressure port and semiconductor die for enhancing chemical resistance.