Quantitative characterization of electromigration-induced plastic deformation in Al(0.5wt%Cu) interconnect

Abstract

Electromigration-induced failure in metal interconnect constitutes a major reliability problem in the semiconductor industry. Recently, experimental techniques capable of probing grain orientation and stress with a spatial resolution compatible with the dimensions of the lines have emerged. White beam X-ray microdiffraction is particularly well suited to the in situ study of electromigration. The technique was used to probe microstructure in interconnects and recently unambiguously unveiled the plastic nature of the deformation induced by mass transport during electromigration in Al(Cu) interconnect lines even before macroscopic damage. The aim of the present research is to understand the complex dislocation structure arising from electromigration-induced plastic deformation by simulating the shape of the reflections and comparing them with the shape observed in the experimental data. We provide a first quantitative analysis of the dislocation structure generated in individual micron-sized Al grains during an in situ electromigration experiment. Custom software allows us to determine the orientation of the predominant dislocation network in each sample subgrain.