Role of phase transformation in possible wear mechanisms in silicon microelectromechanical-system devices

Wear on microelectromechanical-system (MEMS)/nanoelectromechanical-system (NEMS) devices is an inevitable and critical issue. It reduces the lifespan of the device and increases the failure rate. In this study, an atomic force microscope (AFM) was used to investigate wear mechanisms and to devise precautions against wear. AFM made it possible to demonstrate the operational behaviors of MEMS/NEMS silicon-based devices. It was found that the dynamic tip–sample interaction process induces phase transformation of the silicon tip apart from the conventional wear mechanisms. This weakens the mechanical strength of the tip and promotes wear. Evidence of phase transformation in probe tips during scanning was found, and the possibility of the phase-transformation path was also investigated. In addition, the distribution of stress in AFM probe tips with applied force was simulated. Worn probe tips were analyzed based on the Kikuchi patterns, and then high pressure was applied on monocrystalline silicon to determine the possible phase-transformation path. The results provided useful insights into wear mechanisms in silicon-based MEMS devices.