Micro-Contact Performance Characterization of Carbon Nanotube (CNT)-Au Composite Micro-Contacts

This paper presents the micro-contact performance comparison between contact pairs of Au/Au and composite contact pairs Au/Au-CNT. The Au/Au-CNT micro-contact's planar lower contact interface is an Au-CNT composite film with encapsulated CNTs. Micro-contact performance is affected by factors such as applied micro-contact force, temperature, current density, etc. At the micro-contact interface, asperities provide localized points for current flow. Increased temperature at these localized points may soften the contact metal and lead to bridge transfer. Prior work revealed that an Au/CNT contact pair performed poorly compared to an Au/Au contact pair, with two orders of magnitude difference in contact resistance. To maintain micro- contact performance and to reduce thermal effects, a Au/Au-CNT micro-contact was designed and fabricated. This design allows the micro-contact interface to remain Au/Au with the embedded CNTs acting as a thermal conduction conduit below the lower Au contact interface. The upper micro-contact support structure is an Au micromachined fixed-fixed beam with hemisphere-shaped upper contact geometry. The micro-contacts were studied under repeated cycles using an external, calibrated load, resulted in repeatable resistance of approximately 1Ω for nearly 40 million cycles. This research revealed that including a CNT composite film in the lower contact extend the operating life and lower contact resistance as compared to similarly constructed micro- contacts.