Fusion-bond electrical feed-through

Abstract

A semiconductor device has a flexible structure bonded to a semiconductor substructure to form a cavity. The flexible structure is bonded over a conducting feed-through without the feed-through interfering with a hermetic seal formed by bonding. One embodiment of the device includes depressions that contain edges of a diffused feed-through so that imperfections at the edge of the diffusion do not interfere with bonding. The flexible structure is bonded to elevated areas thus hiding the imperfections. In one embodiment, a first elevated region is surrounded by a second elevated region, and diffusion for the feed-through extends from an active region in the cavity across the first elevated region with edges of the diffusion being between the first and second elevated regions. The flexible structure can thus bond to the first and second elevated regions without interference from the edge of the diffused feed-through. A via through the flexible structure to the first elevated region provides electrical contact with the active region. Another embodiment has either a surface or buried well in a semiconductor structure and extending from an active region in the cavity to a point outside the perimeter of the flexible structure. The well provides a conductive feed-through structure without creating imperfections that would interfere with the bonding that seals the cavity.