A novel release mechanism utilizing micro-fuse for CMOS-MEMS micro-mirror

Residual stress developed during thermal processes in fabrication is ubiquitous in MEMS devices. While the residual stress is exploited in many devices to generate initial displacements of freestanding structures in the device [1-2], it can also cause severe problems during and after device fabrications. Post-development of residual stress over long term can deteriorate the performance and even fail the device completely [3]. In the DRIE based microfabrication of our previous CMOS-MEMS electrostatic micro mirrors, sudden release and even crash of microstructures in plasma etching chamber was observed. This is due to the considerable large stress in the multiple-layer microstructures and the low damping effect in the chamber where high vacuum is present [4]. One possible solution to this troublesome final step is to release the microstructures in ambient with higher damping factor.