Electromigration failure development in modern dual-damascene interconnects

The electromigration failure development in typical copper dual-damascene interconnect structures is analyzed based on numerical simulations. The origin of the lognormal distribution of electromigration times to failure is investigated. Also, electromigration-induced void formation and evolution in advanced 0.18 μm dual-damascene lines are simulated and the results are compared with experiments. It is shown that the lognormal distribution of the grain sizes leads to lognormal distributions of the electromigration lifetimes. Moreover, the void nucleation sites and main features of void development are highly dependent on the microstructure of the interconnect lines.