Soi/glass process for forming thin silicon micromachined structures

Abstract

Methods for making thin silicon layers suspended over recesses in glass wafers. One method includes providing a thin silicon-on-insulator (SOI) wafer, and a glass wafer. The SOI wafer can include a silicon oxide layer disposed between a first undoped or substantially undoped silicon layer and a second silicon layer. Recesses can be formed in the glass wafer surface and electrodes may be formed on the glass wafer surface. The first silicon layer of the SOI wafer is then bonded to the glass wafer surface having the recesses, and the second silicon layer is subsequently removed using the silicon oxide layer as an etch stop. Next, the silicon oxide layer is removed. The first silicon layer can then be etched to form the desired structure. In another illustrative embodiment, the first silicon layer has a patterned metal layer thereon. The SOI wafer is bonded to the glass wafer, with the patterned metal layer positioned adjacent the recesses in the glass wafer. Then, the second silicon layer is removed using the silicon oxide layer as an etch stop, and the silicon oxide layer is subsequently removed. The first silicon layer is then etched using the patterned metal layer as an etch stop. The patterned metal layer is then removed.