Analysis of Electromigration in Dual-Damascene Interconnect Structures
Keywords:Electromigration, dual-damascene, interconnect
The effects of grain boundaries on electromigration failure are presented. The electromigration model incorporates the grain boundary as a separate medium which acts not only as fast diffusivity path for material transport but also absorbs and releases vacancies. Moreover, we analyze the void nucleation condition and its implication on electromigration failure is discussed. Our results show that high stress and a high vacancy concentration develop at the triple points formed on the interface between copper grains and the capping layer, where a void nucleation is likely to take place. This scenario of weak triple points in combination with a stress threshold also supports the mechanism of multiple void nucleation as it has been experimentally observed.