Structural Analyses of Thin SiO2 Films Formed by Thermal Oxidation of Atomically Flat Si Surface by Using Synchrotron Radiation X-Ray Characterization

Abstract

Partially crystalline structures in thin SiO2 films formed by thermal oxidation of atomically flat Si surface were investigated by performing X-ray reflectometry and grazing incidence X-ray diffraction measurements. The densities of the SiO2 films were higher than those of amorphous SiO2 films, especially at the SiO2/Si interface. The structure of thermally grown SiO2 has been expected to be amorphous, but sharp diffraction peaks were observed in GIXRD measurements. The diffraction peaks tended to reflect a cristobalite-like structure with preferential orientations to the Si substrate. In addition, the lattice spacing of the cristobalite-like structure was estimated from the GIXRD measurement and found to be isotropically distorted.