Investigation of Similar and Dissimilar Metal Contacts for Reliable Radio Frequency Micorelectromechanical Switches

The evaluation test of various thin film contact materials for reliable radio frequency (RF) microelectromechanical systems (MEMS) switches is presented. Given that two of the most important performance criteria of RF MEMS switches are a low contact resistance and high reliability, the purpose of this study is to search for feasible contact materials and combinations by measuring the contact resistance and hot switching reliability under high current condition. We selected gold, platinum, and iridium for the contact materials and compared the contact resistance and failure point for various similar or dissimilar contacts; Au/Au, Pt/Pt, Ir/Ir, Au/Pt, and Au/Ir using a contact measurement apparatus. Also, we investigated the insertion loss and power handling capability of Au/Au and Au/Ir in the RF MEMS switches. From these studies, it was found that dissimilar contacts such as Au/Pt or Au/Ir are an effective means of enhancing the reliability for high power RF MEMS switches. This evaluation method represents an important step toward the development of reliable metal contacts.