High-stress fatigue experiments on single crystal silicon in an oxygen-free environment

Abstract

In this paper we present the first fatigue study with stress loadings above 2 GPa applied to single-crystal silicon (SCS) resonators in an inert environment provided by the 'epi-seal' encapsulation process. In total, 6 devices representing a total of 16 experiments were actuated for >1010 cycles with stress levels >3.2 GPa at 32°C. No fatigue-like behavior was observed up to 7.5 GPa, which is far beyond the threshold for fatigue reported by others. High-cycle fatigue in SCS is therefore likely to be a surface or environmentally-assisted phenomenon that can be minimized using better packaging techniques, such as 'epi-seal'.