Advanced Packaging and Integration Technologies for Microsensors. Phase 1

Abstract : Advanced microfabrication processes have been developed for producing a hermetic cover wafer with low resistance dielectrically isolated through-wafer interconnects. The feasibility of manufacturing encapsulated pressure sensors, utilizing the cover-wafer approach, has been demonstrated. Such pressure sensors represent a new generation of environmentally protected, cost effective devices. The accomplishments of Phase I include the following: the study of conversion of single crystal silicon into porous silicon; the study of conversion of porous silicon into oxide; process for producing through-wafer interconnects has been established; the stresses in the cover wafer have been investigated, which enabled the fabrication of flat cover-wafers. The surface and cross-sectional morphology of the cover wafer was investigated; hermeticity and dielectric isolation of the oxidized rings was verified; Sensors compatible with the cover- wafer approach were fabricated and tested. The new generation of sensors was designed