Effects of ion energy and arrival rate on the composition of zirconium oxide films prepared by ion-beam assisted deposition

Thin zirconium oxide films were grown using the ion-beam assisted deposition method. Zirconium metal was evaporated by an electron beam and condensed on a Si substrate, while oxygen ions were directed simultaneously onto the substrate, allowing the fundamental deposition parameters of ion energy and arrival rate ratio ARR(O/Zr) to be measured and controlled easily. X-ray photoelectron spectroscopy (XPS) was used to study the oxidation and the composition of the films. XPS analyses indicated the presence of four oxidation states of zirconium (Zr4+ - Zr(1+)) in Zr 3d spectra and two peaks in O 1s spectra; Zr4+ is a predominant ion in all the films and the two peaks in O 1s spectra are related to the oxide and to hydroxyl groups and/or carbonates, respectively. Composition analyses of the films suggested that these oxygen-associated species may be bound to zirconium. The variation of composition as a function of ion energy (from 2 to 20 keV) and ARR(O/Zr) (at 0.54 and 1.09) could be explained with the preferential sputtering of zirconium from the growing film by incoming oxygen ions and the incorporation of oxygen ions into the film. (C) 1996 American Institute of Physics.