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Electromigration damage in thin films of aluminium and aluminium alloy is detected by ac‐measurement of electrical noise. By avoiding defect production by electromigration during the measurement procedure, this technique allows us to study the effect of the electromigration pretreatment on the noise. During the damaging process the noise, which exhibit 1/f power spectra, increases in discrete steps, whereas the electrical resistance increases gradually. The stepwise increase in noise is attributed to the creation of highly mobile defects which do not contribute significantly to resistance. The first step recovers partially under reversal of the damaging current. A transient 1/f2‐component seen in the noise spectra after switching off the damaging current is caused by sudden jumps in the resistance that are presumably due to the relaxation of stress in the damaged metal films.

1/f noise and electrical resistivity of thin polycrystalline aluminum films were measured before and after low‐temperature electron irradiation. Due to irradiation with 3.7×1023 e−/m2 (1 MeV) the noise measured at 10 K increased by a factor of 6 whereas the electrical resistivity increased only by 25%. Subsequent isochronal annealing at progressively higher temperatures caused the electrical resistivity and the 1/f noise to recover. The observed recovery stages in the 1/f noise measured at 10 K occurred at the same temperatures as the well‐known recovery stages of the electrical resistivity of pure bulk aluminum irradiated by electrons at low temperatures. Noise measurements performed at 40 K, however, showed an additional recovery stage at an annealing temperature of about 70 K which has no equivalent in the electrical resistivity.

Electromigration damage in thin aluminum films is detected by the AC‐measurement of 1/f‐noise. Since this technique avoids defect production by electromigration during the measurement it allows to study the effect of the electromigration pretreatment on the noise. A special phase‐sensitive correlation method suppresses background noise and thermal noise. It is found that noise spectra remain nearly constant during electromigration damage until in a late stage of electromigration a sudden increase of noise magnitude takes place. Reversal of the damaging current leads to the partial recovery of this effect. The increase in noise is attributed to the creation of highly mobile defects.