Hello everyone,
I would like to know if a cross-linked SU-8 (2002 to 2010) photoresist is anyhow soluble in solvent like acetonitrile after development and hard bake? The documents I have read about it always stated that it is very difficult to remove the cross-linked photoresist using conventional solvents.
The material under the photoresist happens to be Pt.
Thank you in advance for your expert opinion.
Best regards,
Marie B.
maybe a possible alternative to wet chemical process to strip cross-linked SU8:
https://www.muegge.de/fileadmin/user_upload/muegge.de/Media/MUEGGE-Poster-MEMS-SU-8-Stripping-Process.pdf
There is no solvent that can easily remove cross-linked SU8. As indicated in the post above one solution is an oxygen plasma dry etch.
An alternative (wet etch) approach is Pranha solution (https://en.wikipedia.org/wiki/Piranha_solution).
In both cases the process is one of oxidation, therefore any other materials on the sample that are suceptible to oxidation will also be affected.
I've used MICROPOSIT REMOVER 1165 to detach SU8 from substrate, with mediocre success. it technically doesn't dissolve it, but it swells SU8 enough that in many cases, it just delaminates from the surface.
as a last resort as mentioned above:
if your substrate and device can withstand piranha, (which, many materials won't! ) you can use that. I've used piranha solution to remove hard baked SU8 leftover from my substrates, even when they were thick, i.e., 150 um. Be careful with it and use all safety measures, (you don't want to mess with boiling sulfuric acid,) and good luck!
As a further information, SU8 is being replaced by KMPR photoreist by the same company (Microchem):
http://microchem.com/Prod-KMPR.htm
KMPR is easier to remove, and readily stripped in hot DMSO + ultrasound
regards
Alvise
Thank you very much for these very detailed and helpful responses.
Best regards,
Marie B.
You can remove crosslink SU8 from a silicon wafer by dipping it into sulfuric acid overnight, it works. Now not sure the PDMS will be ok with that. If your problem is to remove SU8 that is stuck inside PDMS, maybe peeling with strong tape can help.
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