A dual ion beam technique was adopted to produce the Zr-O films

of which the composition was studied with RBS and XPS.The results show that all the films consist of three portions: a carbon contamination layer on the uppermost surface

the film bulk where N（O）/N（Zr）=const

and the transition layer between the deposited Zr-O film and the substrate. N（O）/N（Zr） is found to be changed from zero to 2.3 with the increase of oxygen ion beam density. But thicknesses of both carbon contamination layer and transition layer are unchanged for different oxygen ion beam densities. The formation of zirconium oxides in the film bulk was examined by Zr3d chemical shifts.