Atomic-scale electromigration in unpassivated Cu metal lines was directly observed in ultra-high vacuum at room temperature by transmission electron microscopy. It was found that Cu atoms on a (211) crystal plane vanished directionally within half an hour when applying an electric current with a density of 2 x 106A/cm2 through the tested Cu line. The electromigration-induced atomic migration appeared to be anisotropic, and the combination of {111} planes and <110> directions was suggested to be the easiest electromigration system for crystalline copper. Electromigration-induced mass transport was also found to be responsible for the weakening (111) texture of the Cu lines after electric current stressing.

In situ Transmission Electron Microscope Observations of Electromigration in Copper Lines at Room Temperature. C.N.Liao, K.C.Chen, W.W.Wu, L.J.Chen: Applied Physics Letters, 2005, 87[14], 141903 (3pp)