OPTICAL EVIDENCE FOR A SILICON-SILICON OXIDE INTERLAYER

An optical layer 6A thick between silicon and its thermal oxide having an index of refraction at A5461 of 2.8 is required to fit ellipsometric data. Slightly thicker interlayers of lower or higher indexes are also acceptable. Data is introduced through index-thickness plots of an etched-back oxide. Two-quadrant measurements with a null ellipsometer arrangement were used. Corrections for stress-birefringence of the oxide were made. The oxide index is shown to be independent of thickness. Oxides grown at ~900cC require 7-8Å of intermediate optical material, while oxides grown at ~120Q°C appear to need only 4A. © 1979, The Electrochemical Society, Inc. All rights reserved.