Electrostatically actuated failure of microfabricated polysilicon fracture mechanics specimens

Abstract
Polysilicon fracture mechanics specimens have been fabricated using standard microelectromechanical systems (MEMS) processing techniques, and thus have characteristic dimensions comparable with typical MEMS devices. These specimens are fully integrated with simultaneously fabricated electrostatic actuators which are capable of providing sufficient force to ensure catastrophic crack propagation from blunt notches produced using micromachining. Thus, the entire fracture experiment takes place on–chip, without any external loading source. Fracture has been initiated using both monotonic and cyclic resonance loading. A reduction in the nominal toughness under cyclic loading is attributed to subcritical growth of sharp cracks from the micromachined notches in the fracture mechanics specimens. Fatigue fracture has been observed in specimens subjected to as many as 109 cycles, and environmental corrosion is implicated in at least some aspects of the fatigue.