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The relationship among the grain structure, texture, and electromigration lifetime of four Al-1% silicon metallizations produced under similar sputtering conditions was explored. The grain sizes and distributions were similar and the grain structure was near-bamboo for all metallizations. All metallizations exhibited a near-(111) fiber texture, as determined by the pole figure technique. Differences in electromigration behavior were noted. Three of the metallizations exhibited a bimodal failure distribution while the fourth was monomodal and had the longest electromigration lifetime. The electromigration lifetime was directly related to the strength of the (111) fiber texture in the metallization as anticipated. However, whereas the grain size distribution has an effect on the electromigration lifetime when metallization lines are several grains wide, the electromigration lifetime of these near-bamboo metallizations appeared independent of the grain structure. It was also observed that a number of failures occurred in the 8 μm interconnect supplying the 5 μm wide test lines. This apparently reflects an increased susceptibility of the wider interconnect lines to electromigration damage.

Thin films of Al-l%Si were sputter deposited on Si under a variety of pressures of atmospheric impurity gases. The effect of the impurity gases (oxygen, nitrogen, and water), and deposition temperature (15° and 300° C), on the microstructure and properties of the aluminum thin films were studied. The gas pressures introduced during deposition varied from 5 × 10s−6 Torr (6.7 × 10s−4 Pa) to 1 × 10s-10 Torr (1 × 10s−8 Pa). The thin films were investigated by transmission electron microscopy and were found to have a columnar microstructure with an even distribution of silicon precipitates. Both the grain size and silicon precipitate size increased at the higher deposition temperature. A smaller grain size was found in samples that were deposited under the higher impurity gas pressures tested. The specular reflectance of the films was found to be dependent upon the amount of impurity gases present during deposition, the greater the partial pressure the greater the surface roughness. This study also investigated the possibility of using a Resistivity Ratio (RR) measurement to evaluate the grain size of the Al thin films. It has been previously observed that a small Al grain size has poor electromigration resistance. This study found that the correlation between Al grain size and RR values was good indicating that RR tests may be used as a quick, non-destructive measure of film quality.