Analysis of pull-in voltage shift for RF MEMS ohmic switches

The cause of pull-in voltage shift during lifetime test of RF MEMS ohmic switches is explored. During lifetime test, the pull-in voltage of RF MEMS ohmic switches is observed to increase with lifetime test cycles. In order to determine possible causes, two steps are performed. The first is to estimate the effect of cyclic loading on the cantilever on the pull-in voltage of the RF MEMS ohmic switches. The second way is to contrast the switch contact area and bias electrode of failure sample with those of good samples to explore the reason for the gradual increase of the pull-in voltage. The results show that there are no significant changes in pull-in voltages after cyclic loading up to one billion cycles, which means there is no detectable mechanical fatigue after repeated actuation. After the cantilever is removed by FIB, it is found that some of the bias electrode surfaces are damaged in the failure samples, which is considered to be the reason for the gradual increase of the pull-in voltage.