Effects of dielectric charging on MEMS-based grating light modulator

Silicon dioxide and silicon nitride coatings are preferably used as dielectric layers for short-circuit protection in capacitive silicon MEMS based Grating Light Modulator (GLM). However, their tendency to electrostatic charging can diminish the device reliability. The influence of dielectric charges on GLM was discussed. Gas discharges and charges in the air gap of silicon cantilever GLM have been modeled and observed, resulting in surface charge accumulation on the electrode passivation of the devices. The impact of parasitic surface charges on the deflection versus voltage characteristics of bulk micromachined silicon cantilever GLM is investigated and measurements of the charge decay are shown in experimental results. Experimental results agree with the theoretical calculation well, which illustrates the influence of charging and discharging processing. One method is proposed to reduce the influence of dielectric charges.