Low-defect-density silicon on sapphire

Abstract

Low-defect-density epitaxial silicon films on sapphire substrates have been produced using a novel three-step process. This three-step process is a hybrid of vapor-phase epitaxial growth and solid-phase epitaxial regrowth. The solid-phase regrowth is preceded by a simple room temperature Si ion implantation. X-ray rocking curves, MeV helium backscattering and transmission electron microscopy (TEM) are used to evaluate the crystalline quality of silicon-on-sapphire (SOS) wafers produced by this method. The full-width-at-half-maximum intensity of the X-ray rocking curve of this material is typically less than 600 arc seconds for a 600 nm layer. The best backscattering minimum yields at the interface and the surface of the three-step SOS layer are 0.12 and 0.03, respectively. These values indicate that the crystalline quality is much superior to that of normal SOS films prepared by chemical vapor deposition (CVD). Cross-sectional TEM micrographs indicate reductions in both the dislocation and microtwin densities.