Detection of electromigration in VLSI metalizations layers by low-frequency noise measurements

Abstract

A fast, nondestructive, wafer-level method of detecting and characterizing electromigration in VLSI interconnections is presented. Low-frequency (LF) noise measurements have been used to predict lifetimes of aluminum metallization layers. The correlation between mechanisms causing these LF fluctuations and electromigration was investigated. It was found that the activation energies measured using LF noise techniques correspond closely to those for electromigration mechanisms. Through the Arrhenius plot of noise power spectral density, activation energies ranging from 0.60 eV to 0.69 eV were deduced. In addition, the frequency exponent gamma of the 1/f/sup gamma / noise spectrum was studied in relation to electromigration damage in the film. A detailed discussion of these findings is presented form the standpoint of the statistical properties of electromigration. >