I am having a lot of trouble in removing S1813 photo-resist after the etching process. I have already tried Acetone and N-Methyl Pyrrolidinone (PG remover), but traces of PR remain
Hi Bhanu,
Generally 1165 resist stripper is effective at removing the S-series resists, even after baking or hardening due to a plasma etch. Heat some 1165 to 90°C and leave your samples in there for 5 minutes, this will do the job. Longer is fine to, if you want to be safe. For tricky mask geometries you might also want to use a glass syringe to remove any stubborn resist while the samples are sat in the 1165 at 90°C.
Datasheet for 1165 is here: http://wcam.engr.wisc.edu/Public/Reference/Lithography/1165_Remover.pdf
It is a N-methyl-2-pyrrolidine based solution, but has always worked for us. The heating factor may be what is holding you back.
Good luck!
Hi Matthew,
The heating did not work for me either. I heated in Remover PG (N-Methyl Pyrrolidinone) for 20 minutes in 90oC.
Has it got to do with the chemicals? (1165 is N-methyl-2pyrrolidinone and PG remover is N-methyl Pyrrolidinone)
Have attached image of my sample here. Any more suggestions!
Hi Bhanu,
I am no expert on the chemistry here, all I can tell you is 1165 for >5 mins at 90°C definitely works... and if Remover PG doesn't under the same conditions, then I would assume the chemistry is sufficiently different.
Strangely, I can't access the datasheet for Remover PG (www.microchem.com/pdf/removerpg.pdf)... but it is possible it only removes selectively, i.e. it might remove LOR but not image resist. My only suggestion is what I know works - get yourself some 1165!
Depends on what your substrate is made of. Removing photoresist is not always easy. The idea could be to have isotropic etching, like heating acetone at 40C on a hot plate. But to me, I always remove PR with plasma O2, and you can use your ICP-RIE machine for that. When I look to your sample, it makes me think about fried fish ! I believe that if your resist is difficult to be removed, it could be also due to the way you annealed it. If annealing was uncompleted, then Cl2/Ar plasma has also harden the resist during the process. You can also try O3 ashing (ozone). If your substrate allows, you can probably try H2SO4/H2O2 at 110C, or NH4OH/H2O2/H2O. Good luck !
I agree with Laurent's answer. We always do hard O2-plasma (we have no O3) in barrel asher or in plane plate type LF-reactor before putting the samples into stripping agent after F or Cl-based ICP-RIE etching through PR or even Ebeam resist mask. You can start from that, and, if it doesn't help, try to use already offered wet baths (e.g. ammonia with peroxide).
Did you try with aqueous alkaline media such as 2-3% KOH or NaOH. It helps to remove S1813. It worked in my case.
Dear Bhanu,
In order to remove easily your photo resist after hardening you can use the chemicals and methods given by the supplier of the such photo resists.
please follow the following link fro the suitable removals of the photoresist: https://www.microchemicals.com/technical_information/photoresist_removal.pdf
But there is other opinion which render your photoresist easy to to etch. This is the post annealing of your resist. You must not too much harden your photoresist.
You just bake it to be sufficiently resist against the etch solutions for the etching time.
Best wishes
I guess AZ remover at 80 degree C will be compatible even it is shipley resist. The formula is the same (diazonaphtoquinone based resist).
There is a company in France called Technic who have developed some very specific Chemistry to address these issue on positive photoresist. They have a TMAH content as well as resist strip, so they both develop & strip the photoresist.
Please be aware that if you have plasma etched your inorganic layer with an organic mask, you will have inorganic sidewall polymers which are very tricky to remove & not only do you require quite aggressive chemistry , you need very strong agitation (usually some sort of spray tool like the good old Semitool's).
The winning formula is as folllows :-
1. Blanket UV Cure the remaining photoresist
2. Wet clean the film to remove polymers (Spray tool + ACT930 or EKC256)
3. O2 Plasma Ash for final polish
This is what the mainstream semiconductor industry does & continues to do for BEOL (Alu Etch) Photoresist removal.
Have Fun !
Ken
Mostly its depends on photoresist you are using, I am using NaOH 1:10 ration in water @50 degree and it works all time, I am using photoresist made by Etchcut
Fisrt of all, could you tell us the substrate you are using ? Depending on the substrate (GaAs or Si based), the advices might be totally different. I am using AZ stripper at 80degC, I have no problem to remove any resist with this method, or simply a strong plasma O2 in a ICP-RIE (60W platen - 800W coil - 5mTorr - 50sccm O2 - 20deg holder), and BHF if possible (it depends on the substrate).
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