High-resolution resistivity and 1/f noise measurements were performed on isolated via interconnects which were under electromigration stress. The test structures had a volume of about 13, with an internal TiN diffusion barrier. It was found that the 1/f resistance noise of the vias was larger than the 1/f noise in the connecting Al runners; due to the presence of the TiN layer. The application of direct currents led to reversible increases and decreases in resistance, due to electromigration damage, but it had no effect upon the 1/f noise. The magnitude and polarity dependence of the direct current-induced resistance changes were most consistent with the initial electromigration of Cu. At temperatures above 200C, the resistance changes were dominated by abrupt jumps.

G.B.Alers, N.L.Beverly, A.S.Oates: Journal of Applied Physics, 1996, 79[10], 7596-603