Electromigration was investigated, using drift velocity and resistance techniques, in various specimens; some of which were isolated lines that overlapped W studs or lines. Void growth was investigated in sections of lines which extended past the cathode terminal and formed reservoirs through which no current flowed. This was modelled in terms of an electromigration-induced vacancy wind. The activation energy for electromigration was found to be equal to 0.60eV, and to be between 0.9 and 1.1eV, for multi-grained and bamboo-grained pure Al, respectively. The activation energy was equal to 0.77eV for multi-grained pure Cu thin-film lines. The drift velocity of Cu alloys was investigated by using Mg as a solute. This enhanced the Cu drift velocity, whereas Zr or Sn additions markedly reduced the Cu migration rate.

C.K.Hu, K.Y.Lee, K.L.Lee, C.Cabral, E.G.Colgan, C.Stanis: Journal of the Electrochemical Society, 1996, 143[3], 1001-6