Influence of ion implantation on dielectric charging in capacitive RF MEMS switches

Dielectric charging is one of the main problems leading to failure of capacitive RF MEMS switches. In this work phosphorus or boron ions were implanted into dielectric layer by ion implantation. After dielectric layer modification by ion implantation, we focus on investigation of the mechanisms of the charge accumulation and recombination after the sample electrically stressed with 80 V for 30 seconds. A Metal-Insulator-Semiconductor (MIS) capacitor structure is used for such an investigation. Silicon nitride films as the insulator in MIS structure were deposited by LPCVD process. The space charge accumulation in the silicon nitride film can be characterized by Capacitance-Voltage (C-V) measurement. Because of the ionization of the gas in the operating environment of the switch, ion injection by actuation voltage during the operation of the RF MEMS switch will play the role to enhance the charge accumulation in the dielectric layer. Our work offers a principle to understand the effect of the operating environment to the lifetime and reliability of the RF capacitive MEMS switches.