A New Method for Cleaning the Surface of Ultra High-Purity Iron by High-Purity Ozone Exposure and UV Irradiation

A new method by applying high-purity ozone exposure and ultraviolet (UV) irradiation has been used for cleaning the surface of ultra high-purity iron with a carbon contaminated layer. The amount and chemical state of elements on the specimen surface were characterized by X-ray photoelectron spectroscopy. The intensity of the C 1s XPS peak due to carbon contamination was found to decrease with increasing ozone exposure at room temperature. UV irradiation during ozone exposure enhanced the cleaning rate. The XPS results show that contaminated carbon is mainly classified into major aliphatic carbon and minor carboxyl carbon, and their ratio depends upon the condition of ozone exposure. The role of ozone exposure and UV irradiation was discussed with respect to surface cleaning.