Hi Tim

   You can try using the slightly more expensive double sided polished (DSP)
wafers to prevent this from happening.

Phil Tabada


>From: "Postlethwaite, Tim" 
>Reply-To: General MEMS discussion 
>To: "'mems-talk@memsnet.org'" 
>CC: "Knighton, Ed" 
>Subject: [mems-talk] Backside protection from TMAH
>Date: Fri, 11 Jul 2003 11:45:38 -0400
>
>We are etching through-holes in silicon wafers using 20% TMAH and a thermal
>oxide etch mask.  The roughness on the backside of our wafers is causing
>some problems with breakthrough of the oxide mask.  Does anyone know of a
>material that we can paint, spin, or otherwise apply to the backside of our
>wafers that will stand up to the TMAH and can also be cleanly removed?
>
>Thanks,
>
>Timothy A. Postlethwaite, Ph.D.
>Chief Scientist
>Constellation Technology Corporation
>7887 Bryan Dairy Road, Suite 100
>Largo, FL 33777
>office: (727) 547-0600 x6177
>fax: (727) 545-6043
>tpost@contech.com
>
>
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