Formation of subsurface Al 2O 3 layers in aluminum by oxygen ion implantation

Abstract

The use of high-dose oxygen ion implants to create buried, insulating SiO 2 layers in silicon has been reported by many groups. In contrast, only a few groups have studied ion-implanted oxide layers on and in aluminum films. We have investigated the formation of subsurface Al 2O 3 layers in bulk, polycrystalline aluminum. In particular, we implanted (1–16) × 10 17 atoms cm −2 using low current densities of 180 keV O 2+ near room temperature. Depth distributions of oxygen and aluminum were determined using both Auger-electron spectroscopy combined with argon-ion sputtering and helium-ion backscattering. For oxygen fluences greater than about 8 × 10 17 atoms cm −2 our analyses revealed subsurface layers of Al 2O 3 were formed with thicknesses that increased with implanted dose. We combined our results with those from the aluminum film literature to propose a formation process.