251. Improving Reliability of Copper Dual-Damascene Interconnects by Impurity Doping and Interface Strengthening
- Author
-
Yoshihiro Hayashi, M. Sekine, Naoya Furutake, Fuminori Ito, Munehiro Tada, M. Abe, and T. Tonegawa
- Subjects
Materials science ,Metallurgy ,Doping ,Alloy ,Copper interconnect ,Nucleation ,chemistry.chemical_element ,engineering.material ,Electromigration ,Copper ,Electronic, Optical and Magnetic Materials ,chemistry ,Chemical-mechanical planarization ,engineering ,Grain boundary ,Electrical and Electronic Engineering ,Composite material - Abstract
Electromigration (EM)-derived void nucleation and growth in 65-nm-node dual-damascene interconnects were investigated, and the effects of impurity doping as well as copper adhesion strength to a capping-dielectric layer (CAP) are clarified. It is found that surface-reductive treatment of the copper line improves its adhesion to the SiCN-CAP, elongating the incubation time of voiding at the via bottom. An aluminum doping is effective in suppressing both the void nucleation and growth. Consequently, an aluminum-doped copper alloy with the strong copper/CAP interface improves the EM lifetime by 50 times compared to that of a conventional pure copper. These results clearly indicate that blocking migration paths of vacancies through both grain boundaries and the copper/CAP interface is essential in improving the EM reliability.
- Published
- 2007