Lattice Strain of Selectively Grown Silicon Epitaxial Layer

Abstract

This paper reports on the selective growth of silicon epitaxial layers on a (100) silicon substrate having a delineated SiO2 film in an SiH2Cl2-HCl-H2 gas system under atmospheric pressure. The lattice strain of the epitaxial layers was measured using the half angle of the rocking curves and the diffraction contrast of the topographs; these were obtained using the X-ray double-crystal method at room temperature. The elastic strain of the lattice was observed in a selective epitaxial layer having an SiO2 masking film. A weak diffraction contrast was found to remain even after the masking film was removed. This contrast was found to disappear when the direction of the side-wall of the grown layer coincided with that of the incident X-ray projection. The lattice strain was considered to be caused by a difference in the thermal-expansion coefficients of the silicon and the SiO2 film.