Improving performance of the metal-to-metal contact RF MEMS switch with a Pt-Au microspring contact design

Performances of the metal-to-metal contact radio frequency (RF) MEMS switches largely rely on the contacts. A novel contact employing the microspring structure is demonstrated in this paper. The microspring contact can achieve a stable contact at lower actuation voltage, alleviating mechanical wear on the contacts, and can effectively increase the fabrication tolerance. An in-line Pt-Au microspring contact switch was fabricated and characterized. To evaluate the improvement in performance, the results were compared with those of the Au-Au solid contact switch without a microspring design. The highest current handled by the Pt-Au microspring contact was 150 mA per contact, whereas only 20 mA was handled by the Au-Au solid contact. The insertion loss of the Pt-Au microspring contact switch was -0.2 dB at 20 GHz, which was comparable with that of the Au-Au solid contact switch. The isolation of the Pt-Au microspring contact switch was -22 dB at 20 GHz, and that of the Au-Au solid contact switch was -18 dB. With the Pt-Au microspring contact, the switch exceeds its power handling ability and reliability with comparable RF performances.