Francois,
         A very common lift off process is based on a reversal process.  First
expose a reversed image mask to break down the exposed areas to indene
carbo-oxylic acid.  Then treat at 90 degrees Celsius in an ammonia atmosphere.
This diffuses through the resist and neutralizes the acidic areas so no
development can take place.  Then flood expose, this is the only magic area
the amount of flood exposure determines the amount of overhang of the final
developed resist.  Normal figures are from a normal resist image, about 22
degrees to vertical, up to vertical, and 22 degrees past vertical. Normal
develop then use for lift off.  A surprise bonus, the reversed resist is more
resistant to flow with temperature.  There is a paper on one company using
this technique for creating 0.5 micron diameter pillars of resist, 1.2 microns
high.  They then put down TEOS at 425 degrees Celsius with no flow problems.
Let me know if I can help further with papers and or demonstration tests.  Be
assured the tests will stand up to cross country mail.  We have numerous units
in Europe that were the result of mailed tests.  Bill Moffat

-----Original Message-----
From: Francois MONTAIGNE [mailto:[email protected]]
Sent: Monday, July 15, 2002 4:57 AM
To: [email protected]
Subject: [mems-talk] Lift off: Chlorobenzene or LOL-LOR?


Hi everybody

I have to lift off 200 nm thick SiO2 films deposited on various metalic
films. During the deposition of these films by sputtering, the substrate is
heated at temperatures around 100 0C and the lift off is quite difficult
without using a chlorobenzene treatment of the resist (the resist used is
S1813).
Concerning that point, is there somewhere (book or article) a good review
gathering the information about these treatments and the influence of the
different parameters?
It also exists commercial products to help the lift-off process (LOL by
Shipley or LOR by MCC). What are the advantages of these products compared
to the chlorobenzene solution?
Is it possible to strip theses products without using remover but just
aceton?
A 1500C bake seems necessary, is it possible to reduce this temperature?

Thanks in advance for your help...

Francois Montaigne (LPM, University of Nancy, France)
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