Highly Reliable Compact RF-MEMS Contact Switch: Design, Fabrication and Characterization

The dissertation presents techniques that can address reliability degradation of radio frequency micro-electromechanical (RF-MEMS) metal contact switches due to hot-switching damages. In the fi rst proposed technique, sacri ficial contacts are placed in parallel with low-resistance contacts to signi significantly reduce the electric fi eld across the latter. The lower field strength drastically reduces the contact degradation associated with field induced damages. Theoretical and numerical modeling show that the proposed protection scheme introduces minimal, if any, impact on the switch's RF performance. To realize the protection scheme, a novel cantilever structure was designed to allow the correct protection actuation sequence to be realized using a single actuator and bias electrode. Experiments show that, the protected switch design exhibits over 100 times improvement in hot-switching lifetime compared with unprotected switches. In particular, the series-protected switches can achieve 100{150 million cycle lifetime at 1W hot-switching and 50 million cycles at 2W hot-switching before catastrophic failure, in an open-air lab test setup. The second proposed scheme is a shunt protection technique to improve the hot-switching reliability. The proposed technique places shunt protection contacts in front of the main contact of an RF-MEMS metal contact switch to block the RF signal while the main contact is switching on or o . The shunt protection contact creates a local cold-switching condition for the main contact to increase the lifetime of the switch under hot-switching condition. The shunt protection technique can also increase the overall isolation of the switch. Experiments shows that the protected switch has 50 times longer lifetime under hot-switching condition compared with unprotected switch. The protected switch has >100 million cycles and up to 500 million cycles lifetime under 1-W hot-switching condition, measured in open-air lab environment. Besides, the isolation of the shunt-protected switch is 70 dB at 1:0 GHz and 36 dB at 40 GHz, and insertion loss is 0:30 dB at 1:0 GHz and 0:43 dB at 40 GHz. A compact switch design using a single actuator and bias electrode with shunt protection contact was also proposed and experimentally demonstrated