The behavior of electromigration-induced voids (gaps) in a sub-micron wide line on a Ti/TiN conductor was studied by means of  in situ  side-view transmission electron microscopy. Two types of gap were observed. The first type was characterized by extensive growth. The gap caused a decrease in the Al drift velocity upstream in the electron flow. This decrease probably resulted from mass transport, through the exposed TiN surface, and into the gap. The second type of gap did not grow, and later healed. The gap had little effect upon the drift velocity. Mass was transported directly from the cathode-side Al segment, through the gap, to the anode-side segment.

H.Okabayashi, H.Kitamura, M.Komatsu, H.Mori: Applied Physics Letters, 1996, 68[8], 1066-8