A novel isolation technology in bulk micromachining using deep reactive ion etching and a polysilicon refill

Isolation and interconnection of microstructures are important for microelectrical-mechanical system technology, because a microstructure generally acts as both a mechanical unit and an electric unit. In this work, we have developed a novel isolation technology for a bulk micromachining process using DRIE (deep reactive ion etching) and wafer bonding technology, which has gained importance in recent years. The technology combines DRIE and polysilicon refill technologies. A series of polysilicon bars covered by thermal oxide serves as the isolation structure. The structure can be used for flexible or rigid connection between two moveable microstructures or between a fixed structure and a moveable microstructure. The measured isolation and mechanical performance is good enough to realize its function.