Characterization of gold/gold, gold/ruthenium, and ruthenium/ruthenium ohmic contacts in MEMS switches improved by a novel methodology

摘要

Comparisons between several pairs of contactma-nterials are done with a new methodology using a commercialnnanoindenter coupled with electrical measurements on testnvehicles specially designed to investigate microscale contactnphysics. Experimental measurements are obtained to char-nacterize the response of a 5-μm2-square contact bump undernelectromechanical stress with increased applied current. Thendata provide a better understanding of microcontact behaviornrelated to the impact of current at low- to medium-powernlevels. Contact temperature rise is observed, leading to shiftsnof the mechanical properties of contact materials and modifi-ncations of the contact surface. The stability of the contact re-nsistance, when the contact force increases, is studied for con-ntact pairs of soft (Au/Au contact), harder (Ru/Ru contact), andnmixed material configuration (Au/Ru contact). An enhancednstability of the bimetallic contact Au/Ru is demonstrated, con-nsidering sensitivity to power increase related to creep effectsnand topological modifications of the contact surfaces. Thesenresults are compared to previous ones and discussed in antheoretical way by considering the temperature distributionnaround the hottest area at the contact interface.