Robust Fulcrum-Type Wafer-Level Packaged MEMS Switches Utilizing Al-Ru/AlCu Contacts Fabricated in a Commercial MEMS Foundry

This paper reports robust wafer level packaged radio-frequency (RF) microelectromechanical systems (MEMS) switches fabricated in a commercial high volume MEMS foundry. A novel wafer level packaging method is developed to improve the mechanical robustness of the movable shuttle. Two SPST switches are packaged in a single die utilizing a shared seesaw-type membrane that pivots on a fulcrum. Single metal contact (S1) and triple metal contact (S2) switch tips provides low-loss and high isolation respectively. The proposed seesaw-type switch offers a unique solution to improve MEMS reliability with the use of non-metallic thick membrane that minimizes stiction, cantilever sagging/curling, contact degradation and micro-welding problems commonly found in MEMS switches. The packaging method does not degrade the RF performance and operates at 30 V. Packaged S1 MEMS switch shows less than 0.6 dB of insertion loss and better than 20 dB of isolation while S2 switch demonstrates lower than 1 dB of insertion loss and higher than 45 dB of isolation from dc to 20 GHz.