Hi Mario, I have some suggetions for you: > Subject: SU-8 50 Patterning > > I recently bought SU-8 50 resist and I tried to > pattern the resist with the following parameter: I'm using a similar but much simpler process as yours for a 100um layer of SU-8 (SOTEC 70/30 which is about the same as your 50) and it works well. It was developed mainly by a colleague of mine, Louis Guerin. The small size of the wafers you are using certainly makes a difference, but probably a very small one. The spinning speed may have to be adjusted to get the "exact" thicknesses you want. > Sample: Si wafer, about 2cm x 2cm > > Dehydration Bake 1h, 2300C You probably forgot a dot in all our temperature figures. We use: 200°C for 1h > Spinning: 700rpm 5s > 2000rmp 35s For a 100um layer: 1000rpm 40s, acceleration of 200rpm/s 50..60: about 2000rpm (never tried that one) Usually one should start with some seconds of about 500rpm to spread the resist, we dont do that and it works fine anyway. > 10min sheet relaxation Right. I always forget that. > pre bake 2min 500C Hotplate > 30min 900C Hotplate 20min 95°C > Exposure: 9, 12, 15, 17, 19s (5 samples), 23mW/cm^2 min. 200J/cm^2 for 100um > post-bake 500C 2min > 950C 5min slow cool down (2h) 95°C for 15min, quick cool down. No special procedure. Here may lie your problem. If you dont leave the (well) exposed SU-8 at a high enough temperature for long enough, it will not polymerize completely which can lead to funny effects like e.g. cracking. > developing: 10min Dito. Putting the wafer upside down in the solution helps. > After developing the resolution was bad and there > were a lot of rifts on the resist surface. Can anyone help me with > optimized parameters to achieve sheet thicknesses of > approx. 100um and 50...60um with SU-8 50 ?! My parameters are certainly not highly optimized but good enough so far. There are (at least) two pages with a lot or information about SU-8 technology: http://aveclafaux.freeservers.com/SU-8.html http://dmtwww.epfl.ch/~lguerin/SU8NF.html Also Electronic Visions provided me with some helpful information. Cheers, Ralf G. Longwitz. Research Assistant Microsystems integration group Swiss Fed. Inst. of Technology _______________________________ EPFL-DMT-IMS BM 3.125 CH-1015 Lausanne http://dmtwww.epfl.ch/~rlongwit Tel: +41.21-693 6727 Fax: +41.21-693 5950 _______________________________