In this letter a newly developed method of plasma anodization is proposed. This is worked on by irradiating the ultraviolet light onto the specimen of Al thin films. It is observed that the ionic current through the specimen is increased by uv light. And, it could be concluded that the uv irradiation has an effect to enhance the anodization rate.

The thin aluminum oxide film formed by ECR plasma anodization was studied by x-ray photoelectron spectroscopy. It was observed that the composition ratio of the oxygen atom to the aluminum atom is actually smaller than the stoichiometric binding ratio. This result means that oxygen atoms are not easy to be taken into the film during plasma anodization. In other words, the anodization is performed without enough supply of oxygen atoms generated in the plasma. This fact suggests that the oxidation rate is limited by the generation rate of oxygen atom playing an important role in the process of the oxide growth.