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Spectroellipsometric study of buried SiC layers formed by carbon implantation with a metal vapor vacuum arc ion source

SiC material is of intense interest because of its unique properties. Two samples were prepared by carbon ion implantation into silicon substrates with a metal vapor vacuum arc ion source at an energy of 65 keV and a dose of 1.0 X 1018 cm-2. Following implantation, one sample was annealed in nitrogen ambient at 1250 degree(s)C for 10 hours. Spectroscopic ellipsometry (SE) was performed on these two samples (as-implanted and annealed) over a spectral range of 400 - 2000 nm at a fixed incidence angle. In order to lessen the parameter correlation existing in the regression analysis, a multiple sample analysis method was employed. From the interpretation of SE spectra, structural and optical properties of the annealed and the as-implanted samples were derived. SE results confirmed the formation of a thick buried SiC layer for the annealed sample, but the optical properties of this buried layer were found to be different from those of bulk SiC material. For the as- implanted sample, the gradual carbon atom profile was simplified homogeneous composition layers with varying carbon concentrations. The carbon-rich region was treated as a single layer whose optical properties can be represented by one term of Lorentz oscillator, useful information could be obtained.