DETERMINATION OF PROPERTIES OF THIN THERMAL SIO2 ON SILICON BY SPECTROSCOPIC ELLIPSOMETRY

Thin thermal oxide layers grown on silicon by rapid thermal oxidation and furnace oxidation have been characterized using spectroscopic ellipsometry. Oxide thickness (T) and refractive index (n) were determined independently. The problem of correlation in ellipsometric measurements between n and T is addressed. The results show that the relative oxide density, which is related to n, increases as the layer thickness decreases. For a given layer thickness in the range of approximately 80-200 angstrom, furnace oxides grown at 900-degrees-C generally have a higher density than rapid thermal oxides grown at 1050-degrees-C. The data also indicate that densities were more reproducible for furnace oxides of the same thickness than for rapid thermal oxides.