Composition, structure and optical properties of SiC buried layer formed by high dose carbon implantation into Si using metal vapor vacuum arc ion source

High dose carbon implantation into silicon to form a beta-SiC buried layer has been performed by using a metal vapor vacuum arc ion source. The implantation energy and dose are 65 keV and I X 10(18) ions cm(-2), respectively. Post-implantation thermal annealing was carried out at 1250 degreesC for various time intervals in Ar ambient. The composition depth profile, chemical state of C and Si atoms, microstructure and optical properties of the samples have been studied using X-ray photoelectron spectroscopy, Fourier transform IR spectroscopy, cross-section transmission electron microscopy and spectroscopic ellipsometry. For the as-implanted sample, the carbon depth profile shows a Gaussian shape-like distribution with a maximum concentration exceeding the stoichiometric ratio. A clear redistribution of the implanted carbon from the Gaussian shape-like distribution to the two sides is observed during annealing. After annealing at 1250 degreesC for 10 h, a stoichiometric SiC buried layer of approximately 150 nm is formed. Results show the annealed sample is a multi-layered structure of SiO2 surface layer/Si top layer/damaged Si layer/upper interface layer/beta-SiC buried layer/lower interface layer on Si substrate. The optical constants of the beta-SiC buried layer formed by ion beam synthesis are determined from simulation of the measured ellipsometric spectra (2.3-5.0 eV) using an appropriate multi-layered model and the Bruggeman effective medium approximation. (C) 2002 Elsevier Science B.V. All rights reserved.