Kevin, I suspect your resist side walls do not have a reverse camber or slope. With reverse slope no metal is deposited on the side walls and lift off is ensured. We have no problems with up to 40 micron thick resist. The smallest dimensions we have done in a production atmosphere is 0.1 micron metal gate. Contact me directly and I will do free tests and send ample technical papers bmoffat@yieldengineering.com. Bill Moffat -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of D.Grimm@ifw-dresden.de Sent: Tuesday, December 01, 2009 7:19 AM To: mems-talk@memsnet.org Subject: [mems-talk] Problems with EOT Liftoff of 1.5 um diameter holes (Auon GaAs) Hi Kevin, it should be no problem. We use this recipe every day. What happens sometimes is that you burn the resist (you see the non-developed regions opaque) if you are too close to the evaporation source. Of course you should use the AZ as reversal litho to obtain undercut. If you do sputtering, lift-off is much more difficult. Try also hot NMP (80°). I can lift more the 300nm of metal without ultrasonication. Good luck. Daniel