The silanization solution is the problem.  You are implanting Silicon in the
surface os the resist which normal organic removal methods do not attack.  Try
sinification to shake the silicon crust off as you are attacking the resist with
an organic attacker.  I am out of the plant tis week but if it does not work too
well get back to me and Ken Sautter and I will confer on other solutions.  Bill
Moffat

________________________________________
From: mems-talk-bounces+bmoffat=yieldengineering.com@memsnet.org [mems-talk-
bounces+bmoffat=yieldengineering.com@memsnet.org] on behalf of Naa-Dei Nikoi
[deinikoi@gmail.com]
Sent: Saturday, November 19, 2011 8:25 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Stripping Positive Photoresist

Hello,

I do apologise for asking what must be a very basic question. I'm using
S1815 photoresist to create micropatterns for cell culture on borosilicate
glass. I'm pretty happy with the process save for ensuring a good strip.
Part of the patterning process sees me hardbake exposed and developed
coverslips at 120 deg C for 10 minutes before applying a silanization
solution to the exposed glass (1% dichlorodimethylsilane in heptane)  and
curing that at 120 deg C for a further ten minutes -- even so, positive
photoresist shouldn't be that challenging to remove.  When stripping, I
typically wash with acetone followed immediately by isopropanol and then
soak the glass in warmed 1165 ( I warm to 80 deg C then pour over  for ten
minutes before rinsing in isopropanol and water.  I can still see 'shadows'
of the patterns when looking under a light microscope, which I find rather
disturbing.   Unfortunately, I don't have access to an asher or oxygen
plasma -- I'm working in what is very much a 'general' lab.  I've tried an
alternative method of soaking in two changes of DMSO (five minutes each
time) and the results haven't been any better.

Any advice I can get on improving my process I would dearly love.


Thanks,

Naa-Dei