Characterization Issues and ESD Sensitivity of RF-MEMS Switches

Introduction: RF-MEMS switches will probably be one of the most suitable solutions to achieve the goal of small dimension and low power consuming high frequency reconfigurable networks and wireless communication systems [1-2-3]. Complete electrical characterizations have been presented in literature, but very few reporting measurement conditions, both in terms of failure criteria and stress conditions, but also regarding how the same measurements have been made. This lack of standardization can make difficult to compare different devices measured with different systems because the same measurement setup can hide the true behaviour of the device under test. The sensitivity of the MEMS to the ElectroStatic Discharge (ESD) or Electrical OverStress (EOS) has been poorly investigated [4], and in these RF-MEMS switches, to our knowledge, it has not been yet investigated due to their very recent introduction in real applications. Main results: In this work we have investigated how the lack of a standard technique can heavily influences measurement results. Here we report how the point of measurement can affect traditional scattering parameters measures of traditional switches and capacitance measure of single-port MEMS. Furthermore, we have compared DC measurements with pulsed ones showing that the same measure can influence the extraction of the real scattering parameters of the device under test. We have also studied the effects of TLP-ESD events on RF-MEMS switches identifying a very critical ESD sensitivity. In fact, TLP-ESD pulses of only around 250 V (corresponding to a very low 400 V HBM event) applied to the actuation pins produces a potentially dangerous high currents exposing issues related to the device electrode layout. A detailed study of the ESD sensitivity and a standardized technique for testing RF-MEMS switches are then required.