Etching Characteristics of Si(100) Surfaces in an Aqueous NaOH Solution

Chemically treated Si(100) surfaces in an aqueous NaOH solution at 20°C have been studied using spectroscopic ellipsometry (SE) and ex situ atomic force microscopy (AFM). The SE data indicate that a surface native oxide can be etched very slowly by NaOH etching. When the native silicon oxide is partly etch‐removed, the resulting surface is very rough. This occurs because the solution does not etch surface native oxide rapidly, but attacks bulk silicon vigorously. The AFM image confirms a roughened surface of ∼5.5 nm rms. Just after the native oxide is etched away completely, the SE data yield the spectrum of a nearly flat surface, as also confirmed by the AFM observation. © 2000 The Electrochemical Society. All rights reserved.