Thanks for all the comments. I have finally found out the problem. The UV lamp output was much lower than expected, anyway the UV aligner is very old (born in 1981) after all.... Now, I need to double the exposure time to achieve the same exposure dose.... Bill -----原始郵件----- From: Tinka Li Sent: Wednesday, January 23, 2013 6:13 AM To: mems-talk@memsnet.org Subject: [mems-talk] Double layer SU-8 fabrication problem Hi, Bill, I think your problem is why your process that previously worked suddenly failed. The expire date of your resist should not be a problem, but, most probably, your process window is not large enough. You may have marginally succeeded in your previous runs. All lab tools are not well maintained/monitored. Things may have drifted, say, there was maintenance recently, your spinner is slowing down, your hotplate temperature is getting lower, or you just used different tools. So that your 1st Su8 was not dried enough (or less enough than before). Btw, did you measure the 1st SU8 thickness? To remove the wrinkle, in some fabs, it is more or less standard to do a "N2 treatment" (N2 plasma) to passivate the 1st PR layer in double PR layer process. It may also help you. Tinka Prime Wafers Van der Takstraat 8 3071 LL, Rotterdam The Netherlands _______________________________________________ Hosted by the MEMS and Nanotechnology Exchange, the country's leading provider of MEMS and Nanotechnology design and fabrication services. Visit us at http://www.mems-exchange.org Want to advertise to this community? See http://www.memsnet.org To unsubscribe: http://mail.mems-exchange.org/mailman/listinfo/mems-talk _______________________________________________ Hosted by the MEMS and Nanotechnology Exchange, the country's leading provider of MEMS and Nanotechnology design and fabrication services. Visit us at http://www.mems-exchange.org Want to advertise to this community? See http://www.memsnet.org To unsubscribe: http://mail.mems-exchange.org/mailman/listinfo/mems-talk