A robust and reliable RF-MEMS switch fabricated thanks to an original dielectric free design and an innovative process flow

Abstract

Massive integration of RF-MEMS switches is still jeopardized due to reliability issues. To overcome this challenge, this contribution presents a novel electrostatically-actuated MEMS switch. This novel switch integrates a new design: on the one hand a dielectric free actuator on order to reduce drastically the dielectric charging; and on the other hand a symmetrical stacking of the silicon nitride suspended bridge in order to have a switch behavior insensitive to thermal stresses. In addition to that, the process flow has been totally reviewed so as to better control the different gap heights and also reduce contact surface contamination. Among others, thermal oxidations and wet etchings processes are used to fabricate the lower parts of the switch, and amorphous silicon is used as sacrificial layer. Finally, these major evolutions have allowed to demonstrate remarkable results in terms of process capability, microwave performances and lifetime.