A fast reliability assessment method for Si MEMS based microcantilever beams

摘要

In the present study the effect of size and locations of the defects and the loading types on vibrational response and robustness of MEMS Si single crystalline microcantilever beams was investigated. A new vibrational based testing method was developed in order to study the reliability of Si beams and to obtain lifetime curves in a short duration of time. Si microcantilever beams with a proof mass and different notch sizes were subjected to two types of vibrational loads including constant loading at the resonant frequency and sweep excitation covering the first two resonant frequencies. Constant vibrational loading at resonant frequency was applied to obtain the reliability data for the beams in terms of stress amplitude versus time to fracture. In comparison with constant frequency conditions, loading of the specimens by using a fast frequency sweep and the same amount of input excitation energy resulted in a clear reduction of the lifetime of the beams. It was found that the time to fracture was highly dependent on the size of the notches, type of the loading and pre-loading conditions. Finite element analysis was utilized to find the most critical location of the specimen where the induced notch results in the highest stress concentration and also to calculate the stress under which fracture occurs.