Cantilever type radio frequency microelectromechanical systems shunt capacitive switch design and fabrication

摘要

A new cantilever type radio frequency microelectromechanical systems (RF MEMS) shunt capacitive switch design and fabrication is presented. The mechanical, electromechanical, and electromagnetic designs are carried out to get ＜40 V actuation voltage, high isolation, and low insertion loss for 24 and 35 GHz and the fabrication is carried out for 24 GHz RF MEMS switch. The fabricated switch shows lower than 0.35 dB insertion loss up to 40 GHz and greater than 20 dB isolation at 22 to 29 GHz frequency band. An insignificant change is observed on RF performance at 24 GHz (ΔS_(11) =1 dB, ΔS_(21) ＜0.1 dB) after 200℃ thermal treatment for 30 min. The switch is fabricated on quartz wafer using an in-house surface micromachining process with amorphous silicon sacrificial layer structure. Total MEMS bridge thickness is aimed to be 4 μm and consists of 2-μm-thick sputtered and 2-μm-thick electroplated gold layers. The bridge bending models and pull-down voltage simulations are carried out for different stress levels and equivalent Young's modulus (E_(avg)).