Noise measurements in thin-film interconnections: a nondestructive technique to characterize electromigration

Electromigration in aluminum and aluminum-silicon (1%) resistors was detected by means of a new technique based on the particular features of an ultralow-noise amplifier, which made it possible to evaluate the stochastic resistance fluctuations associated with vacancy generation-recombination processes. The power spectra of these fluctuations display a 1/f γ behavior with 2≤γ≤2.6, in the frequency range 10 mHz–1 Hz, and the analysis of these spectra, recorded at various current densities and temperatures, led to an evaluation of the activation energies characteristic of the process. Scanning electron microscope observation of the damage induced by stressing the resistors at the same current density and temperature as the spectra measurement but for a longer time, showed that what was being observed was the electromigration phenomenon in its early stages.