A silicon oxide thin film barrier was prepared with different oxygen ion energies, and its chemical composition, surface morphology, optical, and barrier property related to the deposition condition were characterized and discussed. Our study showed that in O-2-assisted process the stoichiometric silicon oxide thin film was obtained at a critical deposition condition of 100 eV oxygen ion energy. The thin film deposited at the critical condition showed the lowest surface roughness giving similar or higher optical transmittance than that of pure polycarbonate substrate. The boiling and tensile tests performed on the thin film deposited using assisted ions prior to the deposition process showed improvement in the adhesion between the oxide barrier layer and the polymer substrate. In addition, interface domination for improving the barrier properties of silicon oxide thin film was achieved through introduction of dual ion-beam sputtering without pretreatment. (c) 2007 Wiley Periodicals, Inc.