Integrating SOI and Poly-Si Surface Structures Using a Monolithic Process

This work has successfully integrated thick SCS and thin film poly-Si microstructures on a SOI wafer using monolithic processes. Thus high optical quality SOI micromirror and large output microactuators are available using the thick SOI wafer. Moreover, the poly-Si thin film microstructures serve as microhinges and stress-induced self-assembly mechanisms. The microstructures will be lifted and assembled by Si_xN_y/Poly-Si bimorph beams after releasing. This work adopted in-plane movable optical stage and out-of-plane pop-up mirror to demonstrate the characteristic of proposed process. Some reliability testing results showed that the Si_xN_y/Poly-Si bimorph beam was reliable for self-assembly applications. In summary, this integrated process can substantially increase the feasibility and extensibility of fabricating MEMS devices using single crystal silicon (SCS) and poly-Si. In applications, various 3-dimesional optical devices, such as optical switches, variable optical attenuators, and micro-scanners, can be developed by proposed process after assembling the SCS micromirror and poly-Si microstructures.