You can reduce the crystal plane selectivity by adding isopropyl alcohol and/or
lowering
the temperature of the KOH.  The former is much more effective, although it
will also produce
a much less smooth surface, particularly on the floor of a cavity (in (100)).
 The amount of IPA
doesn't seem to be very important at all, it works as long as there is at least
some IPA, which will
float on the surface of the KOH.  This also increases the selectivity to any
boron doped regions.

Marc Straub
Automotive Components Division, Ford Motor Company, Dearborn, MI
313-322-5043    mstraub1@ford.com


On Aug 18, 12:25am, Alexander Barr wrote:
> Subject: reducing selectivity of KOH
>
> Howdy,
>
> Does anyone know how to REDUCE the selectivity of the 100:111 planes for
> KOH etches of silicon.  I do wish to stay with the KOH chemistry.
>
> thanks
>
> ALEXANDER BARR
> xander@utpapa.ph.utexas.edu
>
>
>-- End of excerpt from Alexander Barr