Reliability and long term stability of MEMS

Particular attention to MEMS failure modes is important because failure modes that are negligible at a macroscopic scale become significant on the microscale. Potential modes of failure for MEMS structures include static overload, delamination, creep, and fatigue. We have been examining long term stability through the design of MEMS for accelerated testing. These include cantilever and membrane structures for both static and cyclic loading and stiction. We have identified a potential failure mode in silicon devices that was not previously known. This failure mechanism results from the effect of water on the initiation and propagation of cracks in both single and polysilicon MEMS.