Electromigration in Al/SiO₂ films prepared by a partially ionized beam deposition technique

It has been found that the electromigration resistance of pure Al/SiO ₂ thin films prepared by the partially ionized beam (PIB) deposition technique can be improved significantly as compared to those deposited by the conventional means. The PIB contained 0.8-1.2% of Al self-ions and a bias potential of 2-5 kV was applied to the substrate during deposition. The enhancement of the electromigration resistance of the Al films is believed to be associated with the strong preferred orientation (in the [111] direction) that these films have. Surprisingly the preferred orientation effect is not accompanied by an enlargement of the Al grain size. This combination of preferred orientation and small grain size may find important applications in future very large scale integrated metallization.