Impact of dielectric film thickness on field emission in MEMS capacitive switches

This study presents experimental evidence of field emission in MEMS capacitive switches. Devices with dielectric layers of silicon nitride of different thicknesses between 50 and 200 nm were investigated by current-voltage (I-V) measurements. These measurements were performed at room temperature and under a controlled atmosphere pressure of 3 × 10−2 mbar at bias levels below breakdown and corresponding electric fields encountered in MEMS capacitive switches during pull-in (1-2 × 106 V/cm). Field emission although was not always clearly observed, it occurred in all devices and clearly manifested at electric fields larger than 106 V/cm.