Measurements were made of the activation energy for electromigration in polycrystalline films under clean-surface ultra-high vacuum (less than 10-10Torr) conditions. An isothermal electrical resistance method was used, and a value of 0.47eV was deduced. The results suggested that, under clean-surface conditions, surface diffusion was the main damage mechanism for electromigration in Cu; since the measured energy lay in the range of values that were obtained theoretically and experimentally for surface diffusion on Cu. Scanning electron microscopic observations supported this conclusion.

B.H.Jo, R.W.Vook: Thin Solid Films, 1995, 262[1-2], 129-34