Owen, I'm unsure whether it would make a difference of 50%, but one place to start would be your spinning time. You say you "hold for a few minutes," which is beyond the recommended spinning time of 30 seconds. See the data sheet at: http://www.microchem.com/products/pdf/SU-82000DataSheet2100and2150Ver5.pdf You might also want to lose the acetone in a covered petri dish step. Evening out of the surface by dissolving a different solvent into your resist could certainly affect it during the soft bake. Kevin Paul Nichols MESA+ Institute for Nanotechnology Mesoscale Chemical Systems Meander 151 University of Twente Postbus 217 7500 AE Enschede The Netherlands Office: +31 (0)53 489 26 31 Mobile: +31 (0)6 49 312 471 Fax : +31 (0)53 489 35 95 Email : k.p.nichols@utwente.nl Web : http://mcs.tnw.utwente.nl/ On 3/24/08 6:16 AM, "Owen The"wrote: > Hi all, I've been having some trouble with my SU8 Processing. > Currently I'm using SU8 2100. I'm trying to get a postbaked thickness > of 260um, but I've been consistently getting half the quoted thickness > (130um in this case) for any given speed. > > Here's my processing steps: > > 1) Wafer prep > 2) Dispense 4ml of SU8 on a slowly spinning wafer (to center the blob) > 3) Ramp to the set speed (in this case 1000 RPM), hold for a few minutes and > then stop > 4) Rest in a covered petri dish on top of a small filter with a little acetone > (to even out the surface) > 5) Softbake (ramping to set temps) > 6) Expose and postbake (ramps to temps again) > 7) Develop in acetone, rinse with isopropanol and water > > Not sure what I'm missing, but I've done this process with other > grades of SU8 and have always seen 50% of the quoted film thickness.