It is a question of how handy you are... There are many techniques, I
would say one per user.. I usually use a small cup and pour the resist
into it first. You can remove the bubbles from the cup already, if there
are any, but I usually don't have them. Then pour the resist on the
substrate.. Using a plastic pipette (I'm using one with about 1 mm
diameter), you can again remove the bubbles, if you see some. After
spinning, you can use a blade or any other sharp object... Also, placing
the sample on well-leveled plate and heating up to around 60 deg will
remove few bubbles as the resist becomes more liquid.

Good luck!

J.

-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of frank berisford
Sent: Friday, March 14, 2003 11:08 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Bubbles in my SU-8



Hello all,

I've been trying several different techniques in an attempt to minimize
bubbles in my SU-8.  At first I tried pippeting it onto my substrate
using a large bore pippette.  I also tried dispensing from a syringe and
pouring straight from the bottle.  The pouring seems to work best but I
still get a sizable bubble count.  From here I've tried sucking the
bubbles out with a needle and syringe but to no avail.

I've read of others wiping the SU-8 across the wafers but have yet to
try this method for fear of destroying the substrate.  For what it's
worth I'm using SU-8 2035 with a target thickness of 50microns but I
think I've got my spin recipe locked down.

Thanks for  your time,
Frank Berisford




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