Mode II Measurements for Stiction Failed MEMS Devices

Abstract

Among MEMS devices, the most common type of failure is stiction. Stiction is the unintended adhesion between two surfaces when they are in close proximity to each other. Various studies have been conducted in recent years to study suction. Our research group has shown the in-service repair of the suction failed MEMS devices is possible with structural vibrations. In order to further understand this phenomenon and better predict, theoretically, the onset of repair we have constructed an apparatus to determine the Mode I, II, and III interfacial adhesion energies of MEMS devices failed on a substrate. Recently we have developed a nonlinear model to measure the Mode I interfacial adhesion energies accurately. Using the same experimental apparatus we used earlier to determine the Mode I interfacial adhesion energies, we measure the Mode II interfacial adhesion energies. The proposed experimental method for measuring the Mode II interfacial adhesion energies for suction failed MEMS devices uses a microcantilever beam (1500 μm long, 10 μm wide, and 2.6 μm thick) attached to MEMS actuator with fixed-fixed beam flexure. Deflection of the spring is measured with a vernier scale of the actuator. Then a nonlinear elastic model of the fixed–fixed beam flexure is used to determine the interfacial adhesion energy between the failed microcantilever beam and the surface. In this work, we report our initial results for the interfacial energies from Mode II type failures. A critical strain energy release rate, for Mode II, is found to be G ≤ 549 μJ/m2.