Reinforcement in Electromigration Reliability of Cu Interconnects by Alloying of Extremely Dilute Mno

Nonconformal high-aspect-ratio trenches/vias filling has limited the use of conventional sputtered Ta/TaN liner/barrier for Cu metallization on nanoscaled technology nodes. The self-forming alloyed metallization could offer an alternative barrier-layer/capping-layer thinning scheme for the downsizing Cu interconnects. This study reports an entire-wet process involving trench-filling of electroless plating Cu interconnects alloyed with and without an extremely dilute MnO content of 0.10%. The electromigration (EM) reliability and thermal stability of the Cu(MnO) metallization were evaluated for interconnect applications in in-tegrated circuits. Incorporating the diluted MnO can significantly enhance the EM reliability by a factor of nine by shifting the failure mechanism towards void growth. The failure mode is thoroughly evaluated through analysis of the activation energies and current-density scale factors obtained from Black's equation. The proposed scheme has promised the application for the nanoscaled technology nodes. The reinforce-ment in EM reliability by self-forming Cu(MnO) will be elucidated.(c) 2023 Elsevier B.V. All rights reserved.