Batch-assembled multi-level micromachined mechanisms from bulk silicon

Abstract

The authors report on the development of a new technology intended for the wafer level fabrication and assembly of fully integrated micromechanisms. The technology is based on a boron-doped bulk silicon dissolved wafer process that has been used to fabricate a variety of micromechanical devices. The overall process utilizes three wafers: two silicon and one glass. All the major mechanical elements, including gears and micromotors, are fabricated from one silicon wafer, whereas the mechanical links between these elements are fabricated from a second silicon wafer. These wafers are successively aligned and bonded to a glass wafer which forms the substrate and are then dissolved in EDP to free the mechanisms. This procedure permits wafer-level batch assembly of micromechanical systems. A number of bulk silicon electrostatic micromotors 5-10 mu m thick and gear trains have been fabricated and linked to each other on the same chip.