In-Situ Electromigration Damage of Al Interconnect Lines and the Influence of Grain Orientation

Abstract

AbstractIn this work the authors want to report some experiments concerning unpassivated Al interconnect lines of 8 and 1.4 microns width which have been damaged by in-situ electromigration in the SEM (temperature 230°C, current density 2 and 4×106 A/cm2, respectively). The wider line represents a polygrained structure with few blocking grains spanning the whole width, whereas the narrow line shows bamboo structure. Before electromigration, the local orientation and thus the position of all grain boundaries was mapped by EBSD technique along the entire interconnect line. During and after in-situ current loading in the SEM, the damaged sites were correlated with the grain boundary map to locate where the diffusion paths are situated most likely. It was found that not the deviation from <111> fibre texture, but the misorientation class of the grain boundaries is essential for the localization of the fatal defects.