Effect of Humidity on Dielectric Charging Process in Electrostatic Capacitive RF MEMS Switches Based on Kelvin Probe Force Microscopy Surface Potential Measurements

Abstract

AbstractIn this article we investigate the effect of relative humidity on dielectric charging/discharging processes in electrostatically actuated MEMS devices. The assessment procedure is based on surface potential measurements using Kelvin Probe Force Microscopy (KPFM) and it targets in this specific work PECVD silicon nitride films in view of application in electrostatic capacitive RF MEMS switches. Charges have been injected through the AFM tip and the induced surface potential has been measured under different relative humidity levels. The impact of the charge injection duration and the bias level as well as bias polarity applied during the charge injection step, have been explored. Finally, the effect of the dielectric film thickness under different relative humidity levels has been assessed through depositing SiN films with different thicknesses.