X-RAY REFLECTIVITY MEASUREMENT OF AN INTERFACE LAYER BETWEEN A LOW-TEMPERATURE SILICON EPITAXIAL LAYER AND HF-TREATED SILICON SUBSTRATE

The analytical expressions for thickness and delta (delta = 1 - refrac tive index) of an interface layer from x-ray reflectivity measurements are obtained for an epitaxial layer/interface layer/Si substrate syst em. The contaminated interface layer between the defective epitaxial l ayer and Si substrate is detected by the x-ray reflectivity. The stack ing fault density (SFD) in the epitaxial layer is correlated with the delta of the interface layer. There is a linear relation between the d elta and oxygen concentration of the interface layers. The delta of th e interface layer is less than that of Si which is mainly due to oxyge n in the interface layer. The thicknesses of the interface layers are about 1.4 nm and they do not correlate with the SFDs in the epitaxial layer. The thickness of the interface layer obtained by x-ray reflecti vity agrees with that from TEM observations.