CVD induced by ion beams for the preparation of oxide and nitride thin films

Abstract
The basic principles of the Ion Beam Induced CVD (IBICVD) technique are presented and discussed in comparison with the more common procedure of Plasma Enhanced CVD (PECVD). IBICVD consists of the decomposition of a suitable organometallic precursor by the action of an accelerated beam of O₂⁺ or N₂⁺ ions (E < 1000 eV), depending on whether oxide or nitride thin films are to be prepared. The importance of the ballistic effects in inducing the room temperature decomposition of the precursors is illustrated by some experiments with X-ray photoemission and model organometallic compounds. They account for the high purity of the films prepared by IBICVD, where only minor amounts of carbon or other contaminant species present in the precursor can be detected. High densification and partial amorphisation are typical characteristics of these films that are induced by the bombardment of the growing layer with the accelerated ion beams. An analysis of these major features of the thin films prepared by IBICVD is presented for chosen examples of oxide and nitride thin films. In connection with this analysis, the possibilities of the use of some methods as infrared and X-ray absorption spectroscopies to study the textural and structural evolution of the films are highlighted.