Experimental Study on Repetitive Shock Measurements for MEMS Accelerometers

Shock robustness has become increasingly important in the latest generations of MEMS sensors. Throughout a products life cycle, a sensor can be exposed to external overload situations with forces equivalent to thousands of g's, pushing the sensors functional mass into the surrounding structures. In such scenarios, the sensors recovery is limited by the weak springs forces. With the increasing miniaturization of structures, shock testing during development has become indispensable as adhesion forces become more relevant. In this paper, we describe the Repetitive Shock Routine (RSR) which is a test that can be applied during Wafer-Level Testing. This test is capable of applying thousands of electrostatically induced shock events within seconds while monitoring the sensor's characteristic parameters over time. In this study, over 400 test structures, comparable to consumer MEMS designs, were tested. The evaluation revealed different long-term behaviors of adhesion forces and failure events for in-plane and out-of-plane MEMS structures.