Dynamic Properties of Three-Terminal Tungsten CMOS-NEM Relays Under Nonlinear Tapping Mode

In this paper, we present the electrical characterization of the nonlinear tapping mode of the nanorelays capacitively transduced. Such a characterization is carried out utilizing three-terminal tungsten CMOS-NEM relays. Exciting electrostatically the switching devices near its resonance and detecting its movement by means of capacitive detection, we reveal double-side frequency dynamic-contact characteristics when the displacement is large and the tapping occur in the nonlinear regime. In this way, we take advantage of this periodic contact to evaluate the switching characteristics of the device. We report that the switch stands more than 10 billion of tapping cycles (in a cold switching scenario) without showing any failure. Moreover, we measure current-voltage (I-V) curves before and after the cycling test in order to evaluate the changes produced in the ON-state contact resistance and in the pull-in and pull-out voltages. This test reveals that the characterized switch has a consistent and repetitive pull-in voltage without changing its elastic properties. In addition, we observe that the pull-out voltage decreases slightly and the contact resistance diminishes (from an initial value of 2 GΩ to a minimum value of 735 MΩ. We eventually attribute this result to the fact that the superficial oxide is broken down due to the continuous tapping of the cantilever tip on the contact electrode.