SU-8 developer is actually a pure solvent: Propylene Glycol Monomethyl Ether Acetate (or, PGMEA). It is a common solvent found in many positive photoresists, such as AZP4620. By my understanding, the purpose of using IPA as a rinse solvent is simply because it has the following two properties: 1) It is commonly available 2) It has a higher vapor pressure than PGMEA, and thus dries more easily. It performs the rinse simply as a replacement solvent; that is, as you add IPA, the material that flows off of the wafer is a combination of IPA and PGMEA. Over time, since IPA is continuously added, the concentration of PGMEA reduces. Additionally, in a two solvent system, the material that evaporates off will contain both solvents (although richer in the higher vapor pressure solvent - in this case, IPA), with the combined vapor pressure being higher than the vapor pressure of the least volatile solvent (PGMEA). This will cause any residual PGMEA to dry off much faster. However, as is mentioned in the website referenced, if development is not complete, then sometimes a reaction can take place when the IPA is added, resulting in a white filmy residue on the wafer. I have actually taken to using AZ EBR 70/30 as my rinse solvent for developing SU-8 wafers. It is actually a combination of PGME (70%) and PGMEA (30%), with a resulting vapor pressure very close to that of IPA. However, since the solvents are completely compatible with the SU-8 developer, and with unexposed SU-8, there is no possibility of reaction. 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 suitto kk Sent: Sunday, May 02, 2004 9:05 PM To: mems-talk@memsnet.org Subject: [mems-talk] Rinsing using IPA IPA is listed as a standard rinsing agent by Microchem. However, the discussion in http://aveclafaux.freeservers.com/SU-8.html suggested IPA may not be most appropriate. I would like to query what is the exact functionality of IPA as rinsing? What actually happens when we rinsed the substrate developed in SU-8 standard developer? Does the IPA molecules "takes out" the SU-8 developer molecule by chemically adhering to it and then evaporates quickly with it, or it works on other mechanism? We mixed IPA and SU-8 standard developer and found that the two does not mix. What does SU-8 developer actually contains? Comments and suggestions are welcomed. Thanks for reading this. __________________________________________________ Do You Yahoo!? http://bb.yahoo.co.jp/ _______________________________________________ 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/