Oxidation of Si by Microwave-Excited Oxygen-Plasma through Protective Al Coating

An Al film was formed as a protective layer on a Si wafer. Oxidizing species generated in a microwave-excited oxygen-plasma penetrated the Al protective layer under a UV-light irradiation. The depth profile of the chemical composition of the oxidized film was measured by XPS with Ar-ion sputtering. It was found that the UV-light enhances the oxidation rate through a surface excitation. In O2+N2 mixture plasma, intermixed-insulator films on Si (SiO2-Al2O3-SiO2-Si substrate) were prepared by one sequential plasma process. In O2+H2 mixture plasma, the inner SiO2 layer was not recognized.