Hello Qinghong, there are two very good bilayer materials that I have used. The first is ProLIFT from Brewer Science, and the second is LOR from MicroChem. The LOR is formulated in two varieties for MIF and MIB developers. You can also use AZ's NLOF which is a single layer negative-toned lift off resist. All three should give you good results and clean lift-offs. I am assuming that the geometry you are printing is pretty large. If it is small I would recommend the LOR for sure. Hope this helps. Best Regards, Dustin Warren EV Group invent * innovate * implement Application Engineer - Direct: +1 (480) 305 2447, Main: +1 (480) 305 2400 Fax: +1 (480) 305 2401 Cell: +1 (480) 274 3894 E-Mail: D.Warren@EVGroup.com, Web: www.EVGroup.com -----Original Message----- From: Qinghong Du [mailto:qdu@diconfiber.com] Sent: Monday, February 09, 2009 11:47 AM To: General MEMS discussion Subject: [mems-talk] Bilayer PR for 2um Au lift-off process Hi I am looking for bilayer PR lithography to generate undercut for 2um Au lift-off process. Anyone can sugguest some solutions? Currently I use OCG825 and AZ5214E bilayer PR, but it is not very stable. Thank you for your help. Qinghong DiCon Fiberoptics, Inc.