Hi All,
I am getting a huge problem with patterning on teflon surface. Basically I have Si/SiO2 wafer which is coated with teflon solution and baked properly, so it became completely hydrophobic. I want to etch (RIE) this teflon after patterning on top of the surface. The problem was coming while doing the litho. I am using AZP4620 resist which is thicker and usually used for DRIE/RIE. However, while I spin coating(2000rpm 25sec) and baking (100oC for 90sec) the resist (as per nanofab guideline) behaves absolutely fine. But while doing litho after rehydrating it is over exposing and crumbling. I have used 750mJ exposure which is normally recommended for this resist as per our nanofab guideline.I could not figure out what is the reason. The same recipe is wonderfully working when there is no teflon on the Si/SiO2 surface. Teflon hydrophobicity must be a problem as I anticipate. If any body has any suggestion to work/experience with this resist on teflon surface please let me know.
It sounds like you have a surface tension mismatch. Very few pure hydrocarbon systems will wet or adhere to Teflon. I suggest using a fluorosurfactant. That should guarantee wetting. There are a variety of vendors and types that could be used depending on your system's tolerance.
Thanks a lot Richard for your reply. Do you have any suggestions on the type of fluro surfactant. I saw one of your paper where you worked similar to this topic but it seems we have to synthesize it. But if it is available off the shelf then we can buy it. Let me know any few names of fluoro surfactant. For example PFOA and PFOS will it be good to start with? I have one solvent Fluorinert™ FC-40 but not sure whether it will work as adhesion promoter. I have not tried yet FC 40 though.
http://onlinelibrary.wiley.com/doi/10.1002/adma.201103650/abstract, this would also work but would involve changing the surface chemistry of your teflon
The trademark "Fluorinert" sounds like a 3M electronics cleaning solvent. That would not be an appropriate fluorosurfactant for your system. Since I don't know the exact chemistry, I can make general suggestions only. Avoid the PFOA- or PFOS-based surfactants. They are being removed due to environmental, health and safety issues. The large vendors have removed them already. You should search Dupont for Capstone, 3M for Novec, OMNOVA Solutions for PolyFox. You should also make sure that the chemistry is compatible with your system. All these companies supply good information on their websites and provide small, free samples. I assume the photoresist is a solvent-borne system?
As a side note, my publications in this area have been mainly with commercial fluorosurfactants. I avoid using tradenames in publications.
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