Stable ruthenium-contact relay technology for low-power logic

Micro-electro-mechanical relays are of interest for low-power digital integrated circuits, due to their ideally zero OFF-state leakage current. The first relay-based integrated circuits utilized tungsten (W) as the contacting material because of its excellent resistance to physical wear. However, W oxidizes easily so that the contact resistance increases to an unacceptably high level over the device operating lifetime. Ruthenium (Ru) is a promising alternative contacting electrode material because it forms an electrically conductive native oxide. In this work, challenges and solutions for integrating Ru into a relay fabrication process are described. Ru-contact relays with good switching behavior and more stable ON-state resistance than W-contact relays are demonstrated.