Although bulk silicon is not known to be susceptible to cyclic fatigue,micron-scale structures made from mono and polycrystallie silicon films are vulnerable to degradation by fatigue in ambient air environments.Such silicon thin films are used in small-scale structural applications,including microelectromechanical systems (MEMS),and display "metal-like" stress-life (S/N) fatigue behavior in room temperature air environments.Previously,the authors have observed fatigue lives in excess of 10~(11) cycles at high frequency (approx40 kHz),fully-reversed stress amplitudes as low as half the fracture strength using a surface micromachined,resonant-loaded,fatigue characterization structures.
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