In-situ microscopic study of Cu intragranular electromigration

Electromigration (EM) in unpassivated copper lines at room temperature has been investigated in ultra-high vacuum by in-situ transmission electron microscopy (TEM), The electric current induced atomic migration in a (211)-oriemed Cu grain has been successfully recorded in real-lime video. The atomic image of the (211) grain was found to vanish directionally when applying an electric current density of 2 × 10⁶ A/cm² through the Cu line. The results suggested that the combination of {111} planes and 〈110〉 directions to be the easiest EM path in crystalline copper. By performing selective area diffraction (SAD) analysis on a single Cu grain with (111) crystal orientation, some unusual electron diffraction patterns appeared after passing an electric current through the Cu line. It is believed that the EM-induced Cu twinning may be held responsible for the unique diffraction patterns.