Dear Lib,

"Steps" on the <111> plane are common in Si anisotropic etching
if the mask is not aligned to the crystal planes. The wafer flat
is often not good enough - we found it up to 1.5 deg. off.
For a simple method to align accurately (we achieved <0.1 deg.)
that requires an additional mask, lithographic and shallow etch
step, refer to the following paper:
        M. Vangbo, Y. Baecklund: "Precise mask alignment to the
        crystallographic orientation of silicon wafers using wet
        anisotropic etching", J. Micromech. Microeng. 6 (1996),
        p. 279-284
Hope this helps.

Greetings,
        Frank Berauer
        Senior R&D Engineer
        Hewlett-Packard Singapore


-----Original Message-----
From: lib zhou [mailto:libzhou@yahoo.com]
Sent: Friday, April 12, 2002 2:47 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] the curve phenomenon in si wet etching.


Dear colleagues:

I have a problem with {100}silicon wafer anisotropic wet etching by KOH to
form V-groove. that is the crossline between {111} orientation surface and
{100} wafer surface curved, such as dent line here and there, which make the

{111} surface have high roughness and not plane. In the experience,using
thermal
 oxidate silicon as mask,RIE to make mask figure.can you give me some
information
how to eliminate this curve phenomenon.
Thanks ahead and best regards.

Lib
Yahoo! Tax Center - online filing with TurboTax
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