Reactive sputtering of copper and silicon near the sputtering threshold

Abstract

We have investigated reactive sputtering of copper and silicon by oxygen in the ion energy regime near the sputtering threshold, using low-energy ion-beam and quartz-crystal microbalance techniques. Surface oxidation is observed to increase the ion energy threshold for copper sputtering, and oxide film growth by low-energy ion bombardment of copper and silicon is characterized. It is demonstrated that oxidation of copper is primarily by oxygen ion bombardment, while silicon exhibits greater reactivity to neutral oxygen molecules. Copper oxide layers as much as 150 A thick can be formed at ion energy below the copper sputter threshold at room temperature. No evidence for selective formation of CuO or Cu20 was observed over the range of conditions investigated. © 1985, American Vacuum Society. All rights reserved.