Synergistic enhancement of adhesion and electromigration reliability of cobalt via super-diluted (0.06 at.%) tungsten alloying as next-generation interconnect materials

The demand for high-performance interconnects in electronic devices has prompted extensive research on self-forming copper (Cu) interconnect metallization. However, the investigation of the self-forming process and the corresponding electromigration behaviors for cobalt (Co), a novel interconnect wiring material for next generation semiconductor device, is currently in its early stages. This study reports the fabrication of Co interconnect lines using an all-wet self-assembled nanoseeding and electroless deposition process, and investigates the electromigration reliability enhancement of the Co interconnects through 0.06 at.% of added tungsten (W). Electromigration-induced failure times and current density scaling factors were measured to evaluate the impact of the super-diluted W on electromigration reliability of the Co lines. Furthermore, an evaluation of adhesion properties was conducted, revealing the significant contribution of the added W to the marked improvement in electromigration performance. The incorporation of diluted W (only 0.06 at.%) into Co interconnects could potentially avoid causing a significant increase in residual electrical resistivity. Providing valuable insights into the practical application of Co as a new interconnect material.