A.I. Shah, B.M. van der Wolf, W.J.P.
van Enckevort, E. Vlieg,
Wet chemical
etching of silicon {111}: etch pit analysis by the Lichtfigur method
J. Cryst. Growth 311 (2009) 1371-1377
Abstract:
The Lichtfigur method is introduced to determine the average pit
morphology of etched silicon surfaces. It is an effective method in
surface analysis complementary to optical microscopy. The surface
morphology of silicon {111} after wet chemical etching in aqueous KOH
solution has been investigated by this technique. The morphology does
not change significantly in pure KOH solutions as a function of time.
In solutions containing additive isopropanol, however, the etch pits
evolve from circular to triangular, with a final shape that depends on
the isopropanol concentration. It has been experimentally proven that
the IPA additive does not participate in the etching reaction and no
etching occurs in the absence of water, which implies that OH- only
serves as a catalyst.