Target Mode Transition for Reactive Sputtering —Effect of Gettering by Chamber Wall—

Abstract

  Reactive sputtering techniques have been widely used to fabricate compound thin films. Transition of the target between metallic mode and compound mode is a characteristic feature of reactive sputtering, and needs to be carefully controlled. In this paper, the critical condition for the target mode transition in the Al-O₂ system was studied. First, the conditions for the transition were investigated by varying the amount of sputtered Al atoms and O₂ gas introduced. The ratio of the number of sputtered Al atoms to the number of O atoms introduced was found to be one of the key parameters for the target mode change. Next, the time-dependent variation of the target mode was investigated. The transition time from metallic mode to oxide mode was found to depend on the amount of Al atoms deposited on the chamber wall during pre-sputtering. These results indicate the important role of the chamber wall, which getters reactive gas molecules.