For both KOH and HNA you can use a nitride mask.  For a better etch stop
when removing the nitride people generally place a thin oxide layer
underneath the nitride


Phil Tabada


>From: "M.C Liu" 
>Reply-To: General MEMS discussion 
>To: "General MEMS discussion" 
>Subject: Re: [mems-talk] help for silicon etching
>Date: Fri, 27 Jun 2003 06:48:58 -0000
>
>I had used KOH and HNA in my experiment.But I can't get a satisfied result
>to use nickel mask in KOH and photoresist mask in HNA.Waht's a convenient
>material for mask?
>
>
>----- Original Message -----
>From: 
>To: Sukanta ; General MEMS discussion
>
>Sent: Thursday, June 26, 2003 3:56 PM
>Subject: Re: [mems-talk] help for silicon etching
>
>
> > There are many chemical processes for etching silicon available in the
>literature. Depending on masking material if any that is being used and the
>rate of silicon etch you are looking for we use to use an HF/Acetic/Nitric
>acid. The reaction is very strong with good exhaust required to prevent
>exposure to the operator but is will etch silicon. Bob Henderson
>
>
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