I'm using a bulk KOH-etching process to produce submount structures of
which the revealed {111}-planes are used as a mirror. The envisaged
application requires to etch completely through the wafer. Because of the
long etching time (over 4 hours), considerable underetching occurs.

As far as I know, this effect is due to the slow but finite etching rate of
the {111}-planes. Presuming the [100], [110] and etch ratios of other
planes directly catch up with the {111} (under)etch, the angular
orientation of the {111}-planes would remain at 54.74 degrees with the
{100} surface. Nevertheless, I've measured angles of 53-56 degrees. The
surface quality of the {111}-planes assured me that no mask misalignment
occurred.
Can someone explain this observation?

Kind regards,

Johan.
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Ir.Ing. Johan E. van der Linden

University of Gent (Belgium)
Department of Information Technology (INTEC)
St-Pietersnieuwstraat 41                B-9000 Gent
Tel +32 9 264 33 16        Fax +32 9 264 35 93

e-mail: [email protected]
homepage: http://intec.rug.ac.be/www/u/143
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