Spectroscopic ellipsometry study of (111) and (100)Si surfaces etched in aqueous KOH solution

Spectroscopic ellipsometry (SE) has been used to investigate etching characteristics of (111) and (100)Si surfaces in aqueous KOH solution. A linear regression analysis and an effective medium approximation indicate that when a native SiO x (SiO 2 ) layer is partly etch-removed, the resulting surface is very rough. Just after the SiO x layer is etched away completely, the SE data yield the spectrum of a nearly flat Si surface. The order of the degree of roughness is found to be (100)Si>(111)Si. It is also shown that surface roughening can be greatly suppressed with magnetic stirring.