Hi
What you probably see is the slow attacked of the developer on the quartz
surface.
If you need the original surface you will have to cmp it.
If the resist was uv bake or high temp baked or ion implanted, you might
want to try downstream oxygen plasma strip
shay

-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org]
On Behalf Of Sreemanth M Uppuluri
Sent: Wednesday, May 30, 2007 5:23 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Fused Quartz Cleaning

Hello All,

Thank you all very much for the replies I got for my previous queries. I
have another one now ;-)

I am trying to clean fused quartz wafers that have been used as substrates
several times for coating photoresist (Shipley S-1800 series). I have tried
solvent clean (Acetone & Methanol) and even Piranha (1:1) but still I see
that the surface has some traces of photoresist on it. I would like to know
the best procedure for removing organic and metallic contaminants (Cr,Al)
from fused quartz wafers without affecting the wafer itself. Please let me
know if you have any suggestions.