Electrical and mechanical properties of layered gold–chromium thin films for ohmic contacts in RF-MEMS switches

The electrical contacts are the most critical part for the reliability of RF-MEMS switches. For this reason the development of new contact materials with higher hardness and low resistivity would be of great help in increasing MEMS switch reliability. In this paper a detailed study of mechanical, electrical and morphological properties of gold–chromium multilayers is presented and discussed. It will be shown how hardness of gold can be increased introducing thin layers of chromium inside the gold contact layer. However, some care must be taken, since this improvement can vanish because of thermal and oxygen plasma treatments normally involved in RF-switches fabrication, mainly due to chromium oxidation.