Reliability Evolution of Au-Au, Au-Ru and Au-RuO2 Micro-Contacts

This paper presents a comparison between microcontact pairs of Au-Au, Au-Ru and Au-RuO2. The contact pairs were made with an evaporated Au lower planar contact and sputtered Au, Ru or RuO2 upper hemispherical contact. The RuO2 was reactively sputtered in both a 10% and 25% O2:Ar environment. The evolution of the contact area was observed by actuating the micro-contact to 1, 10(exp 2), 10(exp 3), 5 x 10(exp 3), 10(exp 4), 5 x 10(exp 4), 10(exp 5), 5 x 10(exp 5), 10(exp 6), 5 x 10(exp 6) and 10(exp 7) cycles. The micro-contacts were actuated using an external, calibrated point load. To examine the micro-contact performance, the contact resistance and force required to close the contact were monitored simultaneously throughout testing. At the above stated end point, the microcontact was folded back to evaluate the wear of the upper hemispherical and planar lower contact. The contacts were also examined with an scanning electron microscope to investigate the contact surfaces. This paper will present the contact evolution between contact pairs of Au-Au, Au-Ru and Au-RuO2 microcontacts between 1 and 10(exp 7) cycles. It was found that the contact resistance for the Au/Ru was 1.7 Omega, Au/RuO2 10% was 1.36 Omega, Au/RuO2 25% was 0.036 Omega.