硬 X 線光電子分光による酸化膜の評価

Abstract

We report the applications of a hard X-ray photoelectron spectroscopy to the characterization of SiO2/Si(001) systems. Large escape depth of high-energy photoelectron enables us to probe buried layers and their interfaces in multilayer structures. Estimation of SiO2 overlayer thicknesses up to 25 nm by angle resolved XPS was possible in SiO2/Si(001) samples. Determination of the thickness profile of a wedged shape SiO2 buried layer was successfully done in Ir (8 nm)/HfO2 (2.2 nm)/thickness graded-SiO2 (0-10 nm)/Si(100). The Si 1s core level showed a SiO2 thickness dependent shift, which was ascribed to fixed charge at the SiO2-Si interface. Energy distribution of interface states at ultrathin thermal oxide/Si(100) interfaces were determined by Si 1s core level shift by applying gate bias in metal-oxide-semiconductor (MOS) structure with 5 nm Au gate electrodes.