Selective co growth on Cu for void-free via fill

We report for the first time a highly selective CVD Co deposition on Cu to fill a 45nm diameter 3:1 aspect ratio via in a Cu dual damascene structure. We have achieved void-free Co fill of the via, demonstrating that a selective bottom-up via fill with Co is a potentially viable approach. Defect formation and control in the process and device integration are discussed. This selective process provides an opportunity to reduce via resistance and shrink the minimum metal 1 (M1) area for aggressive standard cell size scaling as needed for 7nm technology.