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| 1 | MEMScyclopedia.org / SU-8 / SU-8 3005 MULTILAYER SOFT BAKE PROBLEM on: 08/07/10 at 06:10:14 |
| Started by kike_escucha | Post by kike_escucha | |
| Hi to everyone, I am doing a project about multilayer with SU-8 3005 and 3050. I have a problem with the soft bake of my second layer, due to a dewetting problem appears, destroying my thin second layer by evaporating all the resist very fast. My steps are: 1. Cleaning with weak acids and plasma. 2. Spinning the first layer (SU-8 3050, thickness of 68um) 3. Soft bake(95șC-30min) 4. Exposure 5. Post exposure bake (65șC-1min/95șC-5min) 6. Spinning the second layer (Su-8 3005, thickness of 5um) 7. Soft bake (95șC-2min) I have tried these times and temperatures with single layer as I read in the datasheet and the results were excellent. I have left 15 min of relaxation at room temperature between the spinning of the second layer and the soft bake, and it gets a little bit better, but still quite bad. So I donŽt know what to do to avoid this very fast dry. I was thinking about ramping the temperature until the final value,but I donŽt think that it is going to work. Thanks in advance for your help!!! |
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| 2 | MEMScyclopedia.org / SU-8 / SU-8 negative photolithography on: 07/30/10 at 06:46:31 |
| Started by arbhuva | Post by arbhuva | |
| Hey guys, I need help with making SU-8 photo lithography. what is the best mask (material) to use in order to block UV light? And why do we use base (silicon wafer, glass slide, micro slide, glass petri dish) and which material is good to use? |
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| 3 | MEMScyclopedia.org / A not so short Introduction to MEMS / Comments on version 4.0 on: 06/08/10 at 23:48:19 |
| Started by MEMScyclopedia | Post by MEMScyclopedia | |
| Please comment on the version 4.0 of the (not so) short introduction to MEMS! Correction, comments, misspelled words : any remark is welcome! |
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| 4 | MEMScyclopedia.org / SU-8 / Re: Problems during softbake (pores emerge) on: 06/08/10 at 23:45:57 |
| Started by hkaren | Post by MEMScyclopedia | |
| Not completely sure what is wrong here, but it may be good to start with a better cleaning of your surface : you should use a more aggressive Piranha (H2O2:H2SO4) immersion to remove any organic contaminant there (oil or such residue). Then you would think of something wrong with the tools you use: - check the temperature of the hotplate - it looks as if the hotplate is too hot and the solvent does not have time to diffuse through the thick SU8 layer, forming bubbles. Check it with an external thermometer... - check the SU8 - maybe it is too viscous (old bottle?) and you get a very thick layer - check the spin-coater : is it OK, and really 2200rpm? Maybe it is slower and you get a much thicker layer again... Tell us if you found an answer... even if it is a dumb mistake  |
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| 5 | MEMScyclopedia.org / SU-8 / Problems during softbake (pores emerge) on: 04/01/10 at 12:13:37 |
| Started by hkaren | Post by hkaren | |
| Hi all, I am grateful for the very informative encyclopedia and forum. I think that the creators have done a terrific job. I found a lot of important information but still could not find the answer to my problem. I am new to the photolithography and the first time I ever tried to create a template everything worked out perfectly (beginner's luck), but after that I have been having problems with creating templates. After applying the photoresist (SU-8 50) and spinning it everything seems fine until I try to softbake. During the softbake process pores or dimples or small islands (bubble-like) emerge. I am not sure how to call them but small circular features emerge everywhere on the surface. Here are my steps: I use SiO2 thermal wafers and regular microscope slides. 1. Pre-clean in ultrasonic bath for 5 min. in acetone and 5 min. in alcohol. Dry with a stream of high purity nitrogen. 2. Pre-bake in 120C oven for 15 min. 3. Leave it to cool down for 10min-15 min. 4. Use SU8-50 and spin under 2200 rpm, under slow acceleration. (I have also tried to coat the whole surface with thin layer of SU8 and apply more in the center before the spin) 5. Softbake for 6 min at 63-65C (this is where my problem starts to occur) on hot plate then slowly increase temperature to 96C and leave for another 20 min. 6. Leave it to cool down for 10min. 7. Expose for 35 sec. under 480mW UV source. 8. Post-bake for 1min at 65C and 6min at 95C on hot plate. 9. Develop for 8min. 10. Rinse with alcohol and dry with a nitrogen stream. (I use striped photomask) Once I had the SU8 stripes peel-off from the surface when I immersed the template into alcohol after developing. I have been struggling with this issue for over a month and I would appreciate any help or suggestions. Thanks, Karen |
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| 6 | MEMScyclopedia.org / SU-8 / Re: Thin layer of SU8 on: 03/17/10 at 18:44:22 |
| Started by Miro G | Post by MEMScyclopedia | |
| ref 1 is the paper 1 in the references section of the SU8 page : D. Stumbo, and J. Wolfe, "Ion exposure characterization of a chemically amplified epoxy resist", J. Vac. Scien. Technol. B 11 (1993) : 2432-2435, you can find it at http://dx.doi.org/10.1116/1.587000 if you have the access right to the Journal in your institution... Actually, there is not much about recipes there, although they do 0.25”m line using 0.2”m-0.3”m thick layer, it was very early work and the whole recipe is only roughly given ('the resist was further diluted in PGMEA to obtain the desired thicknes' Furthermore it is for e-beam lithography, not UV... For exposure dose and baking time use the data provided by MCC, plot it and use your eyes to extend the curve beyond the measured data points... Good luck... and do not forget to report your success here |
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| 7 | MEMScyclopedia.org / SU-8 / Re: Thin layer of SU8 on: 03/08/10 at 01:03:46 |
| Started by Miro G | Post by ineedhelp | |
| I'm using a diluted solution of SU8 2000.5 (1:2 with cyclopentanone) to use with an interference holgraphy setup, but I'm not sure about exposure times etc. This "ref 1" sounds like it could be useful for me, but I don't know where to find it. Apologies if it's obvious and I'm being a bit slow. |
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| 8 | MEMScyclopedia.org / SU-8 / Very thick SU-8 layer and glass adhesion on: 01/18/10 at 20:23:48 |
| Started by Tanya | Post by Tanya | |
| Hi all, I am new to the SU-8 fabrication and I have two problems: 1) I would like to make a very thick SU8 layer of about 750um. What would be the bast way to do that? There is SU8 2150 from MicroChem, in the guidelines they discuss the procedure for thickness only up to 550um. Could I prepare the desired thickness by making one layer of about 400um and then another of 350nm? Or is there a better way to make such thick layers? 2) I would like to use glass slides instead of silicon. There is already a topic on SU8 adhesion on glass, but the link appears to be dead... As I understand the adhesion to glass is quite poor and it is better to use an adhesion promoter. Can somebody recommend? Many thanks, Tanya |
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| 9 | MEMScyclopedia.org / SU-8 / Re: Thin layer of SU8 on: 01/05/10 at 06:49:20 |
| Started by Miro G | Post by MEMScyclopedia | |
| The transparency of SU8 in this range is very good. MCC sells SU8 2000.5 that would be close to what you want to have (0.5um @ 3000rpm and probably close to 0.3um at 5000rpm). Anyway it is always possible to dilute existing SU8 to get even thinner solution : use the proper amount of GBL or cyclopentanone to get a lower viscosity (take care it is weight % use properly density of SU8 and solvent). From the existing data we see that dividing the solid content by 2 allows decreasing thickness by 5, thus you should get 0.2um @ 3000rpm by using a mixture close to 10% solid. Some data on thin layer of SU8 may also be obtained from the early literature on SU8 (ref 1 in the list). And don't forget to report back how it goes! |
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| 10 | MEMScyclopedia.org / SU-8 / Thin layer of SU8 on: 12/29/09 at 20:08:00 |
| Started by Miro G | Post by Miro G | |
| Hi I need to deposit a thin layer (>0.2um) of dielectric isolator. It needs to be transparent to a broad band of wavelength (600-1000nm) and smooth. I thought to use SU8 but I dont know if I can do it as thin as I need. Did anyone have experience using SU8 in these thicknesses? If so, which SU8 (or other materials) did you used with what parameters? Thanks, Miro G |
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