An RF MEMS switch with a differential gap between electrodes for high isolation and low voltage operation

摘要

A double-actuation RF microelectromechanical system (MEMS) switch with high isolation and low voltage operation for RF and microwave applications is presented. The operation voltage of the suggested double-actuation vertical RF MEMS switch structure was reduced without decreasing the actuation gap. Theoretically, the operation voltage of the suggested structure is about 29% lower than that of a single-actuation vertical RF MEMS switch with the same fabrication method, electrode area and equal contact gap. The proposed RF MEMS switch was fabricated by surface micromachining with seven photo-masks on a quartz wafer. To achieve planarization and the stair-like structure, a polyimide sacrificial layer was spin-coated, cured and etched in two steps and patterned by a dry etching step which defines the double-actuation mechanism. The measured results of the fabricated RF MEMS switch demonstrate that the insertion loss was lower than 0.11 dB for the 20 V ON state, the isolation was higher than 39.1 dB for the OFF state and the return loss was better than 32.1 dB for the 20 V ON state from dc to 6 GHz. The minimum pull-in voltage of the fabricated RF MEMS switch was 10 V.