Optical Detection And Minimization Of Surface Overlayers On Semiconductors Using Spectroscopic Ellipsometry

Spectroscopic ellipsometry can be used to assess in real time the effectiveness of etching and cleaning methods in reducing the amount of unwanted interface material (oxides, contamination, pits, damage, etc.) at the surface of a semiconductor. However, we show that an unambiguous response denoting removal of interface material occurs only in certain wavelength ranges. We have applied this technique to determine chemical procedures that yield the sharpest dielectric discontinuities (smoothest and/or cleanest surfaces) for Si, Ge, and some III-V compound semiconductors.