Aluminum-Aluminum Oxide Metallurgy for Enhanced Electromigration Resistance in Monolithic Circuits

During the past decade the semiconductor industry has used vacuum deposited aluminum films for inter - connection both in bipolar and MOS devices. The major disadvantage of aluminum films, however, has been their early failure due to electromigration (1-4). When subjected to high current densities, aluminum films are found to degrade, form voids and finally become electrically discontinuous thus shortening the life of the devices. During recent years extensive work has been reported on electromigration in aluminum both from the point of view of understanding the phenomenon and with a view to improving the life of the devices using aluminum as the interconnection metallurgy (5-8). An Al + A12O3 alloy has been shown to exhibit superior electromigration resistance (9) and has been postulated that this might be related to higher creep resistance.