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

Abstract

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.

Research and Analysis of MEMS Switches in Different Frequency Bands

“…The contact resistance of 2.4–1.8 Ω at 90–100 V was achieved in open laboratory environments (nonpackaged). Liu et al [ 102 ] designed a metal-to-metal contact MEMS switch based on a Pt–Au micro-spring contact. The thickness of the top contact part was decreased alone.…”

Analytical Approach in the Development of RF MEMS Switches

“…Medium-power handling switches (10-100 mW) fail due to high contact current density and contact microwelding. This problem is solved by the selection of materials with better contact characteristics [47][48][49][50]. For high-power handling switches (100 mW or more), the main failure mechanism is temperature rise, high current density and microwelding of contacts.…”

Fabrication and thermal stability characterisation of Ru electrode used for high power contact radio frequency microelectromechanical system switch

“…In the past few years, there have been some researches using different high melting point metals as the contact metal to improve power handling ability. Pt [3], Ru [4], Rh [5] and Ir [6] have been reported as contact materials and their performances have been further investigated via a nanoindenter [5, 6]. These researches show that the Ru–Au and Pt–Au contacts perform better than the Au–Au contact in high current (100 mA) and have at least ten times longer lifetime than the Au–Au contact in a hot switch cycle test.…”