Lawrence Berkeley National Laboratory

We report here an in-depth synchrotron radiation based white beam X-ray microdiffraction study of plasticity in individual grains of an Al (Cu) interconnect during the early stage of electromigration. The study shows a rearrangement of the geometrically necessary dislocations (GND) in bamboo typed grains during that stage. We find that about 90percent of the GNDs are oriented so that their line direction is the closest to the current flow direction. In non-bamboo typed grains, the Laue peak positions shift, indicating that the grains rotate. An analysis in terms of force directions has been carried out and is consistent with observed electromigration induced grain rotation and bending.