5:1 BHF (that's 5 NH4F : 1 HF by volume) is the most common and is
well-documented. See etch-rate papers online.
Mixes stronger than about 3:1 tend to lift off the resist  a lot faster.
    --Kirt Williams

----- Original Message -----
From: "Andrea Mazzolari" 
To: "General MEMS discussion" 
Sent: Thursday, May 17, 2007 11:51 PM
Subject: Re: [mems-talk] Quartz Etching


> Which is BHF composition, which product from Shipley series are you using
> ? And which is etch time?
>
> Andrea
>
>> Hello All,
>>
>> I am interested in etching quartz using photoresist as the mask. From a
>> reference I found that BHF etches quartz at high speed and does not
>> affect
>> Shipley series photoresist. But when I did perform the etch I found that
>> the
>> photoresist has all been removed by the BHF solution. Can you please let
>> me
>> know what is going wrong. I am presently not using PDMS adhesive layer
>> before coating photoresist on quartz. Could this be a reason?
>