LOW-FREQUENCY ELECTROMIGRATION NOISE AND FILM MICROSTRUCTURE IN AL/SI STRIPES - ELECTRICAL MEASUREMENTS AND TEM ANALYSIS

Low frequency (1/f(gamma)) noise, generated by current densities at which electromigration occurs, and the temperature coefficient of resistance between 40 and 100-degrees-C were measured on Al/Si(1%) test patterns. The samples had different microstructures, obtained by sputtering the films onto substrates held at five different temperatures. The microscopic features of the samples (average grain dimension) were analyzed by means of transmission electron microscopy. It was found that, at a given frequency, the noise power spectral density of the voltage fluctuations is a decreasing function of the average grain dimension. This fact agrees with the hypothesis that low frequency electromigration noise is not a bulk effect, but originates mainly at grain boundaries