2) I would check the thickness of the PMMA after the descuming step.

4) I would remove PMMA in NMP instead of Acetone. Warm up the NMP at about 80oC.
Sonication may help.

Regards,

Pedro Barrios



-----Original Message-----
From: mems-talk-bounces+pedro.barrios=nrc-cnrc.gc.ca@memsnet.org [mailto:mems-
talk-bounces+pedro.barrios=nrc-cnrc.gc.ca@memsnet.org] On Behalf Of landobasa
Sent: June 1, 2010 11:09 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] PMMA cracking during e beam evaporation

Dear Researcher,

I am still a beginner in fabrication, and I have these following problems in the
lift-off process. In order to provide the context, let me briefly write the
process steps:

1) PMMA film (200nm thickness) is patterned using Electron  Beam Lithography
(developed for 60s and IPA for 30s).
2) Patterned PMMA film was subjected to UV Ozone Stripper (SAMCO UV-1) for 60s.
3) The sample was deposited by Ti with 20nm thickness (with the rate of
0.06nm/s)
4) The sample was soaked in Acetone.

Problems:
1) There are cracks everywhere in PMMA film after E-Beam Evaporation.
2) The PMMA cannot be removed by acetone.

Any help would be very much appreciated.

Best Regards,

Lando