A method of fabricating MEMS accelerometers

In this paper we present a promising method for the fabrication of MEMS accelerometers. The method should be easily adapted to fabricating other devices such as pressure sensors, gyroscopes, and micro mirrors as well. Of the device SOI wafer is used to fabricate the sensing element and glass wafer is used as the substrate to support the device and for metal interconnects and signal I/O. Wafer bonding and silicon deep reactive ion etch (DRIE) are the two major techniques employed in the fabrication processes. Both DRIE before wafer bonding and wafer bonding before DRIE approaches look feasible and were used for the fabrication process. The interconnect metal is seriously damaged during anodic bonding in the wafer bonding after DRIE approach whereas the metal is intact if the wafers are bonded before the DRIE process. Heat dissipation is a critical issue in the DRIE process for silicon on glass structure. A metal layer deposited on the backside of silicon is proved to be effective to eliminate the problems caused by poor heat dissipation. All the major technical issues have been resolved in process development. The process yield is high and can be easily transferred to volume production.