Gabe, As Greg said, your best option to begin with is to try to make sure that your substrate is sufficiently dehydration baked. Baking the wafer at 150C for a minute or two, and then allowing to cool to room temperature (either on a cool plate or ambient cooling) prior to coating should accomplish this. HMDS (even in a YES vapor prime oven) will have little positive effect at all (except perhaps from the dehydration standpoint), since there is no attraction between SU-8 and HMDS. Should dehydration bake not work for you, there is also an adhesion promoter recommended by MicroChem and produced by Silicon Resources in Chandler AZ called AP300. One final note, and that is, verify that you are supplying a sufficient exposure dose to the SU-8. Since SU-8 is a negative acting material, insufficient exposure can result in a non-exposure condition of the material closest to the silicon. Upon develop, this layer dissolves, causing the cross- linked region to lift off. For tests sake, you can try a severe overexposure (granted, you may sacrifice a substrate to do so, unless your feature sizes are very large) and see if this makes the material stick. 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 Greg Reimann Sent: Monday, May 17, 2004 8:44 AM To: 'General MEMS discussion' Subject: RE: [mems-talk] Re: SU8 Adhesion to Si Gabe, How thick are your SU-8 layers? Is it the first soft bake that causes the problem? Does the adhesion fail during or after the bake? I did not have a lot of success with HMDS and Microchem's promoter Omnicoat is for metals, not Si/SiO2. The SU-8 normally has really good adhesion to Si/SiO2. I don't know what a YES oven is, but generally, you want to stay away from ovens with SU-8. You want hotplates so that the solvent bakes out from the bottom up. Here are some things to watch for: Make sure you are baking the water out of the wafer before you apply the SU-8. Don't thermally shock it. Make sure you are doing a two step or ramped bake. Let it cool on a thermal insulator, like a plastic container. If your trouble comes after exposure, make sure you are filtering out stray wavelengths shorter than i-line. Hope this helps. Good luck, Greg Reimann Boston University -------------------------------------------------------- The SiO2 is currently present on the wafer. Would the adhesion benefit from HMDS or perhaps a YES oven process? - thanks - Gabe _______________________________________________ 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/