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

Low frequency (1/f(gamma)) noise, generated by current densities at wh ich electromigration occurs, and the temperature coefficient of resist ance between 40 and 100-degrees-C were measured on Al/Si(1%) test patt erns. The samples had different microstructures, obtained by sputterin g the films onto substrates held at five different temperatures. The m icroscopic features of the samples (average grain dimension) were anal yzed 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 electromigrati on noise is not a bulk effect, but originates mainly at grain boundari es.