Suspensions shape impact on the reliability of ohmic RF-MEMS redundancy switches

Abstract

The influence of the suspension shape on the electrical parameters and on the reliability of micro-machined ohmic series and shunt RF switches has been studied in this work. We have investigated how different spring constants influence the electrical parameters of RF-MEMS switches, in terms of the pull-in voltage, the pull-out voltage, and the evolution of scattering parameters during the DC sweep. The robustness to cycling stress has also been studied, considering different movable structures and bias voltages. We have also analyzed the behavior of RF-MEMS switches submitted to long continuous actuation, finding that meander based devices could suffer from extremely long release times, after an actuation period of some hours. However, straight beam based switches have not exhibited this problem. This unwanted behavior has been analyzed in terms of actuation time and RF-power level. The presence of bounces in the release phase has also been investigated on various types of switches with different topologies and suspended membrane thickness.