A VERTICALLY INTEGRATED MEDIA-ISOLATED ABSOLUTE PRESSURE SENSOR

A novel, media-isolated, temperature-compensated, bulk-micromachined i ntegrated absolute pressure sensor has successfully been developed. Th e sensor is usable for most applications involving exposure to harsh m edia, such as fuel vapor seen by manifold absolute pressure (MAP) sens ors. The device consists of two dice bonded together. Devices are batc h fabricated by bonding two wafers together prior to sawing. The botto m wafer contains bulk-micromachined piezoresistive pressure sensors an d the top wafer contains signal-conditioning integrated circuitry. The pressure sensors and the integrated circuits are coupled together by wirebonding from the top die down to the bottom die through via holes anisotropically etched in the top wafer. Characterization of the devic e indicates that the devices fabricated meet the specifications of a M AP sensor. (C) 1998 Elsevier Science S.A. All rights reserved.