Qing, I would suggest a negative acting chemically enhanced resist. The advantage is that the resist is transparent so that side wall angles are nearly 90 degrees. Gary Gary Hillman Service Support Specialties, Inc. 9 Mars Court PO Box 365 Montville, NJ 07045 973-263-0640 973-263-8888. -----Original Message----- From: Qing Yao [SMTP:qingyao@uiuc.edu] Sent: Monday, February 16, 2004 12:19 PM To: MEMS-talk Subject: [mems-talk] thick photoresist development Hi, I have difficulty in patterning thick photoresist. The following is what I did: 1> coat a 4" Si wafer with 5 layers of AZ4620 using a spinner. The thickness of each layer is about 10 microns and the total thickness of PR is about 50 microns. Bake the wafer at 110 degree centigrade for 1 min. after the deposition of each single layer. 2> print the image pattern on a transparency (emulsion down) using a 5080-dpi laser printer. put the transparency mask on top of the PR layer and put a 4" quartz plate on top of the mask. Then do Fusion Flood exposure. the dose is about 3300 mJ/cm2. Lots of bubbles are generated during the exposure process. 3> use 1:4 AZ400K to develop the PR for about 9 minutes. I used both optical microscope and surface profilometer to measure the side wall. The slope angle is about 50 degrees. However, I need the slope angle to be close to 90 degrees (at least larger than 80 degrees) so that it is almost perpendicular to the substrate. What can I do to achieve it? Would you please give me any suggestions? by the way, the thick photoresist layer is sort of mold (for electroless plating of Ni on Si substrate). Best Regards, Qing Yao ___________________ M&IE @ UIUC _______________________________________________ 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/