Data on the evolution of stress, in thin-film metallization wires during transient electromigration, were reported. The strain-sensitivity of the X-ray micro-beam topographic technique permitted real-time spatially resolved measurements to be made using the lowest currents (104 to 1.4 x 105A/cm2) yet reported. The steady-state results agreed qualitatively with the Blech stress-gradient model, but the threshold-length product which was calculated from the data was some 2 to 3 times smaller than previously reported values. The stress evolution in the transient state exhibited local fluctuations which could not be attributed to experimental error. This was attributed to possible microstructural effects upon local flux divergences; even in the case of wide non-bamboo wires.

Topographic Measurement of Electromigration-Induced Stress Gradients in Aluminium Conductor Lines. P.C.Wang, I.C.Noyan, S.K.Kaldor, J.L.Jordan-Sweet, E.G.Liniger, C.K.Hu: Applied Physics Letters, 2000, 76[25], 3726-8