An Investigation of the Properties of an Epitaxial Si Layer on a Substrate with a Buried SiO2 Layer Formed by Oxygen-Ion Implantation

Abstract

We have investigated the crystallographic properties of a silicon substrate with a buried SiO₂ layer formed by oxygen-ion implantation (¹⁶O⁺ dose: 1.2 to 2.4×10¹⁸/cm²) and an epitaxial silicon layer on the substrate using the step-by-step sample thinning technique. The surface silicon layer on the buried SiO₂ layer was found to have a dislocation-free single-crystalline silicon region, but with small precipitates of oxide. The epitaxial silicon layer grown on the surface silicon layer was found to have a high density of dislocations. The dislocation density was 2×10⁹/cm² and was almost constant for a substrate oxygen dose above 0.6×10¹⁸/cm². The dislocations are considered to be caused by precipitates in the surface silicon layer. However, the epitaxial layer had fairly high mobility and no stacking faults.