Repair of Stiction Failed MEMS Using Structural Vibrations

Abstract

It has been shown in recent times that the use of structural vibrations is a viable approach in repairing stiction failed MEMS cantilever beams. It has also been observed that such a technique is sensitive to various parametric values associated with the de-sticking of these beams. In the current paper we present experimental results which characterize the ideal cantilever beam. An analytical model of stiction failed MEMS cantilever beams under electrostatic actuation is presented. Physical parameters such as stiffness, bending rigidity, damping, excitation voltage, etc. are incorporated in terms of Mathieu parameters to study the stability of the system. An experimental characterization of natural frequency, Young’s Modulus, and damping ratio, which form important components of the analysis, is presented. Accompanying these results is a description of the experimental set up used for finding these parameters. Experiments were performed at both atmospheric and vacuum pressures. An interferometric microscope mounted above the glass window of the vacuum chamber was used to determine the crack length of each beam and observe the profiles of the arrays of microcantilevers in-situ. A Laser Doppler Vibrometer was used for determination of characterization parameters. The microcantilevers were fabricated using the SUMMiT IV process of Sandia National Laboratories. Structural vibrations were induced by placing an alternating voltage on a cofabricated actuation pad located under the microcantilevers near their anchor point. Theoretical modeling shows the dependence of physical parameters that lead to stiction repair.