Charge collection mechanism in MEMS capacitive switches

The present paper investigates the effect of stressing bias magnitude and stressing time on the discharging process in MEMS capacitive switches. The calculation of discharge current through the dielectric film is based on monitoring the rate of shift of bias for up-state minimum capacitance. The data analysis shows that the discharge current lies in the range of femto-Amperes and the calculated discharge time constant depends directly on the time window of observation and on the stressing conditions. Moreover the analysis reveals an increase of trapped charge that remains in the bulk of the dielectric film for very long time as the stressing bias increases. The dominant discharge process, taking place under an intrinsic field of about 10³ V/cm, is found to be the hopping effect.