Patrick, I have a couple of questions. First, what film thickness are you aiming for? And, second, which grade of SU-8 are you using (i.e., SU-8 25, SU-8 2050)? If you are creating a pretty thick film, one thing you can do is greatly extend the high temperature (95C) bake step, or perhaps perform an additional bake step in an oven at 95 C (for several hours). It probably won't completely take care of the problem, but considering that the Tg of SU-8 is 55 C, some reflow will occur during that period to reduce the height of the edge bead. If you can manage it, try to use a thicker grade of SU-8, which will allow you to spin on at much higher RPM. This can do a lot to minimize edge bead (although you will still have some pretty big problems at the corners of your substrate). Since your samples are small squares, there is not a whole lot else that can be done to reduce the edge bead. Best Regards, Chad Brubaker EV Group invent * innovate * implement Technology - Tel: (602) 437-9492, Fax: (602)437-9435 e-mail: [email protected], www.EVGroup.com This message and any attachments contain confidential or privileged information, which is intended for the named addressee(s) only. If you have received it in error, please notify the sender immediately and then delete this e-mail. Please note that unauthorized review, copying, disclosing, distributing or otherwise making use of the information is strictly prohibited. -----Original Message----- From: [email protected] [mailto:mems-talk- [email protected]] On Behalf Of Patrick Poissant Sent: Monday, March 29, 2004 6:12 PM To: [email protected] Subject: [mems-talk] SU8 spin-coating Hello, I have small samples (1cm square) and try to spin-coat SU8 resist on it. I apply my ressit with a pipette directly on the samples and then spin-coat. I also try to spin slowly when appling the resist. These two ways produce big edge bead. How do you spin-coat SU8? How big are your samples? Best regards, Patrick Poissant ___________________________________________________ M.A.Sc. Student Dept. of Electrical Engineering Université de Sherbrooke Sherbrooke (Québec) J1K 2R1 CANADA [email protected] Sherbrooke Microelectronics Research Group www.gel.usherb.ca/gms Anyone who has never made a mistake has never tried anything new - Albert Einstein _______________________________________________ [email protected] mailing list: to unsubscribe or change your list options, visit http://mail.mems-exchange.org/mailman/listinfo/mems-talk Hosted by the MEMS Exchange, providers of MEMS processing services. Visit us at http://www.memsnet.org/
