The Effect of Multi-Directional Stimuli on the Stiction-Induced Failure Behavior of MEMS

The occurrence of adhesion-induced failures at microelectromechanical systems (MEMSs), also referred to as stiction, can be triggered by a variety of environmental, geometrical, and operational parameters, such as compressive contact forces acting in normal direction between two micromechanical surfaces. The knowledge of these parameters is essential for conducting and evaluating stiction-related reliability tests at MEMS. This paper investigates the operational parameter of tangential contact forces, which can occur in case of multi-directional overloads like shocks or vibrations during manufacturing, handling, or final application of MEMS inertial sensors. Tangential contact forces act in parallel to a contact area and are shown to affect the stiction-induced failure behavior of MEMS. For this purpose, three different types of test devices have been exposed to electrical as well as mechanical stimuli with and without cross-axes excitation contents, stimulating the occurrence of tangential forces during contact. The transient system responses of the test devices were calculated based on reduced-order impact models, allowing a detailed comparison of load conditions between different stimuli and test devices. The obtained results show that tangential contact forces lead to higher stiction rates, which indicates increased adhesion forces compared with excitations without tangential forces.