The effect of crystallographic texture upon excess noise, and the use of excess noise monitoring to predict the electromigration behavior of pure Al films was examined. The magnitude of the noise, and the logarithmic slope, were measured in 3 distinct sets of Al films as a function of line-width (0.5 to 2). The electromigration lifetimes of the films had been shown to be directly related to the (111) volume fraction. The present study showed that the excess noise was inversely proportional to the (111) volume fraction; thus suggesting that the noise might not reflect the same rate-limiting atomic process as did electromigration. The effect of the film texture, together with a decreasing magnitude of the noise with decreasing line-width, implied that grain boundaries were a major source of noise in Al films.

R.G.Smith, G.A.Biery, K.P.Rodbell: Applied Physics Letters, 1994, 65[3], 315-7