The effect of dielectric charging on capacitive MEMS switch

Based on a one-dimensional model of dielectric charging for capacitive RFMEMS switches, the accumulated charge density and actuation voltage shift were simulated. The results illustrate that rougher surface can reduce dielectric charging, so the dielectric layer should be fabricated much rougher during deposition process. But the capacitance ratio of switch will be decreased with rougher surface, which can cause a reduction of switch performance. Thus the dielectric surface roughness should be balanced in reliability and isolation.