Initial observation and analysis of dielectric-charging effects on RF MEMS capacitive switches

Capacitance voltage and RF-output characteristics of electrostatically actuated MEMS switches were measured under different control and stress voltages. It was found that positive voltage stress caused negative charging of the dielectric whereas negative voltage stress caused positive charging of the dielectric. This is consistent with the amphoteric nature of traps in the silicon oxynitride dielectric used for the switches. A hypothesis of charge injection in minutes and charge migration in milliseconds was proposed to explain real-time and nonsymmetrical drift of pull-down and hold-down voltages of the switches.