Bonding of a Carbon Nanotube Film to a Au Film at Low Temperature and Contact Resistance of the Film under Micronewton Loads

Abstract

A process for bonding a carbon nanotube (CNT) film to a Au film at low temperature was developed with a view to using the CNT films as electrical contact materials in radio-frequency microelectromechanical systems (RF MEMS) switches. First, a CNT film was synthesized on a silicon substrate at 750 °C and subsequently coated with Au at room temperature. Finally, the Au-coated CNT film was bonded at 100 °C to a Au film, which was then deposited on a silicon substrate to act as a transmission line. An apparatus was developed to measure contact resistances and forces under contact conditions mimicking those that will be encountered in actual RF MEMS switches, such as micronewton loads and square-micrometer contact areas. Contact resistance and force of the bonded CNT film sample were simultaneously measured as a function of displacement between the sample and an electrode Au tip and compared with those for a Au film and Au-coated CNT film. The bonded CNT film sample had no adhesion force, but higher contact resistance than the other samples.