Reliability enhancement by suitable actuation waveforms for capacitive RF MEMS switches in III-V technology

In this paper, the reliability of shunt capacitive radio frequency microelectromechanical systems switches developed on GaAs substrate using a III-V technology fabrication process, which is fully compatible with standard monolithic microwave integrated circuit fabrication, is investigated. A comprehensive cycling test is carried out under the application of different unipolar and bipolar polarization waveforms in order to infer how the reliability of the realized capacitive switches, which is still limited with respect to the silicon-based devices due to the less consolidation of the III-V technology, can be improved. Under the application of unipolar waveforms, the switches show a short lifetime and a no correct deactuation for positive pulses longer than ~10 ms probably due to the charging phenomena occurring in the dielectric layer underneath the moveable membrane. These charging effects are found to vanish under the application of a waveform including consecutive positive and negative voltage pulses, provided that proper durations of the positive and negative voltage pulses are used. Specifically, a correct switch deactuation and a lifetime longer than 1 million cycles, being this value limited by the duration of the used testing excitation, are achieved by applying a 1-kHz waveform with 20-?s-long positive and negative consecutive pulses.