Chemical grafting to improve electroless deposition of self-aligned barriers

Among the challenges raised by the integration of copper in advanced interconnects, the improvement of reliability performances is a constant concern, To address this issue, it has been proposed to use metallic capping barriers deposited by electroless means. However, the industrial implementation of these processes is not straightforward, due to their intrinsic instability. In this study, we propose to enhance their selectivity and robustness by using a grafting step, which consists to selectively chemisorb selected organic precursors on top of the copper lines, before the barrier deposition. The organic precursors are designed to selectively attach to the copper surface, and to enhance surface reactivity towards metallic ions.