Another thing from my experience. The adhesion between SU-8 and glass substrate seems fairly much depending on the surface conditions (maybe roughness) of the substrate. There are a couple of times I ran borofloat wafers using exactly the same process (pirahna cleaning, dehydtration, spinning, soft bake, exposure and PEB) but SU-8 patterns show up nicely on some wafers without any peel off after development for a few mins, while nothing is left on other wafers with the same develop time. Because the wafers used are mixed from different vendors, I could not trace down the difference between their surface quality. However, besides surface conditions, I could not think of any other factors contributing to this huge difference in adhesion. So, try some other glass substrates if nothing else helps. Xianling Chen On Tue, 15 Jun 2004, Brubaker Chad wrote: > There could be a few different reasons for lift off of your patterns during develop: > > 1: The initial adhesion to your substrate is poor. In this case, ensure that you are performing a dehydration bake (150(C, 1-2 minutes on a hot plate) prior to coating. If you are doing this already, then you may want to contact Silicon Resources (at siliconresources.com) for a supply of their AP300, which has been shown to enhance adhesion with SU-8. > > 2: You are underexposing your film. Bare in mind, you are patterning a negative material on a transparent substrate. You are not getting the radiation reflection that you could expect from a silicon substrate, so the standard recommended dose may not be sufficient. With a negative material, if your dose is insufficient, you may not get crosslinking at the bottom layers of the material (especially with SU-8, where the photoactive compounds will not diffuse and migrate within the film after activation). If the material is not crosslinked, it will actually develop out (dissolve) in the developer solution, causing liftoff. > > 3: Your post-exposure bake is not correct. The recommended post exposure bake is with a hotplate. Due to the thickness of many SU-8 films, heat transfer in an oven environment may hamper the curing of the portion of resist closest to the wafer. The material may remain under-crosslinked, and again dissolve in the developer. > > Best Regards, > > Chad Brubaker > > EV Group invent * innovate * implement > Technology - Tel: (602) 437-9492, Fax: (602)437-9435 e-mail: C.Brubaker@EVGroup.com, 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: mems-talk-bounces+c.brubaker=evgroup.com@memsnet.org [mailto :mems-talk-bounces+c.brubaker=evgroup.com@memsnet.org] On Behalf Of annuar > Sent: Monday, June 14, 2004 5:55 PM > To: mems-talk@memsnet.org > Subject: [mems-talk] SU-8 adhesion to glass substrate > > Hi everyone. > I'm having problem coating my glass slide with SU-8 resist. It seems that > the SU-8 does not adhere very well to glass. After developing, some part of > my patterns are lifted off. Does anyone know how to solve this problem? Does > the softbake or PEB have anything to do with this? Thanks. > > Abang Annuar > > > > _______________________________________________ > MEMS-talk@memsnet.org 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/ > > > _______________________________________________ > MEMS-talk@memsnet.org 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/ >