Hi David:

Yah, actually with no agitation this problem occurs easily - I think you
need to add little agitation, to remove the etched silicon - this is a fast
etchant, the HNA get diluted locally near etching position.

----- Original Message -----
From: "Foehl, David" 
To: 
Sent: Saturday, January 05, 2002 3:54 AM
Subject: [mems-talk] HNA etching


> I am having difficulty with HNA silicon etching and wondered if anyone has
> insight on how to resolve it. Currently, I am using 15%HF, 78%Nitric and
7%
> Acetic with the etch rate of >3um/minute, with no agitation and excellent
> surface finish/uniformity. The problem I am having is the etch rate
> diminishes over time <2um. The interesting thing is; if I let the solution
> set for a period of time it returns to the original >3um/minute. How do I
> stabilize this? 150mm wafer w/8 liter solution.
>
> David Foehl
> Development Engineer
> Innovative Micro Technology
> 805-681-2826
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