Study On Failure Mechanisms Of Capacitive RF MEMS Switch With High Power Handling Capacity

Capacitive RF MEMS switch will self-actuation, latch and self-heating at more than 30 d Bm power RF signal handling situations, which lead to failure of switch, and limit its application in communication system. In order to design Capacitive RF MEMS Switch with High Power Handling Capacity, it is necessary that analyze the failure mechanism of the above three failure modes. The corresponding analytical model of high fidelity threshold power or failure behavior model should be established. And then lay theoretical basis for the reliability design of the switch.In view of the fringing field effect influence on the analytical model accuracy of self-actuation threshold power of the switch, a figure of merit is constructed in this paper to characterize the intensity of the fringing field effect. And then the threshold power model of the switch with the fringing field effect is constructed. The calculation precision of the model is improving.In view of the degradation of down-state capacitance influence on the analytical model accuracy of latch threshold power of the switch, the comparative modelling method between the 3D electromagnetic simulation and the equivalent circuit simulation is proposed in this paper. The function relationships between the surface roughness of dielectric layer and the degradation of down-state capacitance are identified. And then the analytical formula of latching failure threshold power of the switch with smooth dielectric layer is revised to predict the power handling capacity of the switch with rough dielectric layer.In order to establish a complete self-heating failure behavior model of the switch, it is necessary that the failure mechanisms are analyzed and the failure modes are described by proposing the electromagnetic-thermo-stress multi-physics cooperative simulation method. The linear relationship of the drift between the actuation voltage of the switch and the incident power(0 ~5W) of the RF signal is fitted. And the theoretical support is provided for switch design of resistance to thermal stress deformation.