Abstract: A new process is being developed for fabricating micromechanical structures using SOI material. This paper will review the process and show preliminary data for accelerometers made using the process. The focus of micromechanical technology at the C.S. Draper Laboratory, Inc. has been on the developement of inertial sensors, gyros, and accelerometers. Many of our current devices are fabricated using a dissolved wafer process. The resultant devices from that process are boron-doped silicon structures suspended over thin-film electrodes on a Pyrex substrate. It is a particularly attractive feature of this process that thick structures can be fabricated with small electrode gaps. Although this process has led to many excellent device results, requirements for future devices give reason to explore alternative technologies such as the SOI process, which yields an all-silicon device while preserving many of these advantages. Experimental devices were fabricated using a geometry similar to accelerometers being made by the previous process. Although not all of the geometric goals were met, the results are promising. Among the expected advantages for the new process are: a better thermal expansion match between device and substrate, the ability to add on-chip electronics, better alignment, and the capability of fabricating new types of structures. !3
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