A non-obtrusive technique to characterize dielectric charging in RF-MEMS capacitive switches

Degradation and failure due to dielectric charging has been a dominant and pervasive reliability concern for RF-MEMS switches. Traditionally, the operational lifetime dictated by this degradation phenomenon is extrapolated from a series of measurements of time-dependent shifts in Capacitance-Voltage (C-V) characteristics under accelerated stress conditions. In this paper, we explain why the classical large-signal C-V methodology may lead to a pessimistic under-prediction of device lifetime. Using both simulations and experiments, we propose and verify a new small-signal characterization technique based on resonance characteristics of MEMS cantilever beams. This new technique overcomes the limitations of the classical approaches to accurately anticipate device lifetime and opens up the possibility of non-obtrusive, in-situ runtime monitoring of degradation in RF-MEMS switches. Moreover, since the technique is amenable to `parallel´ implementation, it has the potential to be used both as an in-line process monitor as well as to reduce the overall time to technology qualification.