Nonconformal Al via filling and planarization by partially ionized beam deposition for multilevel interconnection

It is shown that by using a partially ionized Al beam with an ion-to-atom ratio of ≃ 1-2 percent and a substrate potential of several kilovolts, one can fill deep and narrow vias at a substrate temperature of ≃ 210°C in a nonconformal way. Very little Al coating was found on the sidewalls of the vias, subsequent deposition at a higher temperature (∼320°C) resulted in partial planarization of the Al layer. This method is potentially useful in multilevel interconnection applications.