Development of electroless Co via-prefill to enable advanced BEOL metallization and via resistance reduction

A novel metallization scheme was developed to enable advanced BEOL interconnect scaling. The proposed approach adopts electroless Co to selectively grow Co in vias, followed by conventional Cu metallization for the trench. We have demonstrated the feasibility of this approach through the process integration of electroless Co via pre-fill on a two metal layer interconnect test structure. A detailed discussion on the yield improvement, parametric data, and reliability will be presented in this paper.