Ion-beam-assisted deposition of Al 2O 3 thin films

Abstract

The density, composition and microstructure of Al 2O 3 films grown by the ion-beam-assisted deposition (IBAD) technique were studied. This technique involves direct evaporation of Al 2O 3 by electron (e) beam while simultaneously bombarding with 300–500 eV O 2 + ions. The arrival rates of ions and atoms were adjusted by varying the ion current and deposition rate respec- tively. The composition and density of the films were determined by a combination of Rutherford backscattering spectroscopy, thickness profilometry and cross-section transmission electron microscopy, while the microstructure was studied by plan-view transmission electron micro- scopy. The hydrogen content of the films was also analyzed using the proton recoil detection technique. IBAD of Al 2O 3 resulted in an amorphous phase with substrate at room temperature and a crystalline η phase at a substrate temperature of about 600 °C. The IBAD films at 600 °C had bulk-like densities (about 3.7–3.9cm -3) and they were free from pores. The stoichiometry of these films was about the same as the bulk stoichiometry. The IBAD film at 600 °C contained a very small quantity of hydrogen atoms (about 1.48×10 21cm -3) as compared with a regular e-beam-deposited film (about 4.4×10 22cm -3).