A novel electrostatic Radio Frequency Micro Electromechanical Systems (RF MEMS) with Prognostics function

Radio Frequency Micro Electromechanical Systems (RF MEMS) has emerged as one of the most promising front runners in wireless components market because of their high linearity, high isolation, ultra-low power consumption, and the capability of integrating with integrated circuits for portable wireless communication devices. However, their widespread application in commercial areas is hampered by the relatively poor reliability performance during long-term usage. Among the failure mechanisms of RF MEMS, stiction induced by the charge accumulation in the dielectric layer is the predominant one, accounting for most of the failed components. However, the origin of the accumulated charge, its properties and distribution, and its adverse effect on devices´ electrical performance has not yet been fully understood. In this paper, we propose the design, realization, characterization, and reliability test of a novel RF MEMS capacitive switch which has a high RF performance and low fabrication cost with a capability of predicting its state of health for various applications from phase shifters to tunable antennas. The key characteristic of our design is the introduction of Prognostics and Health Management (PHM) using non-intrusive monitoring method, which allows us to calculate the remaining useful life of our RF MEMS capacitive switches and provide a warning before its onset of failure. We overstress the device using two methods: electrostatic discharge (ESD) and operational voltage waveform. We discovered the difference of RF MEMS behavior and lifetime. We also present the effect of driving voltage polarity on the lifetime of RF MEMS.