Analysis of Electromigration in Dual-Damascene Interconnect Structures

We have analyzed the stress build-up and vacancy dynamics due to material transport caused by electromigration in dual-damascene interconnect structures. Our model incorporates all relevant driving forces for material transport with a complete integration of mechanical stress in connection with microstructural aspects. First, it is shown that the addition of redundant vias can be effective in increasing the interconnect lifetime, although the spacing between the vias can have a significant impact on such an approach. Then, we discuss the importance of grain boundaries in providing triple point intersections, where the combination of high vacancy concentration and high stress is likely to cause void nucleation.