Titanium MEMS Relay
We present an investigation into the viability of a new route for the fabrication of titanium-based MEMS RF switches for harsh environment applications. Titanium’s intrinsic toughness and corrosion resistance suggest that it would be highly suitable for such applications. Recently developed titanium micromachining technologies now make exploration of this potential possible. Two design generations of electrostatically-actuated Bulk-Titanium MEMS (BT-MEMS) switches were fabricated and tested. First generation devices demonstrated that actuation at moderate voltages could be achieved (~60V), however stiction upon contact was common. This stiction was mitigated in the second generation devices through design modification and development of a new Titanium on Insulator (TOI) based process. These devices displayed stiction-free actuation and relatively low contact resistance. These preliminary results therefore demonstrate the potential of this process technology for fabrication of titanium-based RF switches for harsh environment applications. For additional information, please contact Changsong Ding.
	We also integrated a nanostructured composite contact material for improving the contact reliability of MEMS switches. The nanocomposite material was integrated into a bulk titanium MEMS (BT-MEMS) switch which was fabricated using a sacrificial layer free (SLF) processing technique. Above 15 billion cold contact cycles were achieved without adhesion failure.
	Contact resistance trends according to the contact cycle number. Note that the contact resistance is low (~0.5Ohm) starting from the beginning cycles. The low contact resistance at the beginning cycles benefits from the flip-chip bonding technique which eliminated the use of sacrificial layer and the contaminations caused by it. Auger scan at the contact spot shows that the carbon concentration is very high after 15 billion contact cycles. Very little gold was seen comparing to carbon. The SEM photograph of the contact spot is shown at the lower-right corner.