EVALUATION OF DEPTH PROFILE OF DEFECTS IN ULTRATHIN SI FILM ON BURIEDSIO2 FORMED BY IMPLANTED OXYGEN

A simple technique is presented for evaluating defect profiles in ultr athin Si films on buried SiO2 formed by implanted oxygen. A combinatio n of thinning by sacrificial oxidation and epitaxial him growth by UHV -CVD is used. By measuring the defect density of the epitaxial film wi th respect to the thickness prior to epitaxial growth, the profile of the initial defect density can easily be evaluated. This technique is applied to evaluate the Si on insulator structure fabricated by state- of-the-art technique, in which low dose oxygen implantation (similar t o 4x10(17) cm(-2)) and high temperature internal oxidation processes a re used. The defect density at the surface of the film is 250 cm(-2). However, as the buried interface is approached, the defect density inc reases. The defect density at 20 nm from the buried interface is as hi gh as 6x10(5) cm(-2). A defect generation mechanism is also discussed. (C) 1996 American Institute of Physics.