Microstructure and texture analysis of narrow copper line versus widths and annealing for reliability improvement

In this article, we focus on the possible influence of interconnect Cu microstructure on electromigration phenomenon. First three annealing conditions were applied on interconnects. Microstructure and texture of copper were characterized by Electron BackScattered Diffraction (EBSD). Then electromigration tests have been carried out on 70 and 150nm line widths of 45nm node technology. In both cases no significant difference was observed in term of reliability performance versus annealing conditions. On the contrary large difference is observed on Electron BackScattered Diffraction results. Then, a statistical approach was used to investigate local microstructure and texture of copper for 150nm line width. The results underline that morphological parameters of copper can vary versus annealing conditions but lead to similar reliability performances. We can thus conclude that these parameters are not in relationship with electromigration phenomena in these interconnects. On the other hand, high amount of misorientation has been highlighted as responsible of early failures.