LithoTalk

[jk]

Hello!

I posted this already in the German forum, but there might be somebody who doesn't speak German:
I am using Argon plasma to etch thin gold layer on GaAs, using AR P 3840 photoresist as a mask. The problem is to remove the photoresist after etching. I tried aceton and toluol, I also tried the remover AR 300-70 (recommended by the producer), even at about 80?C, there are still small rests of the resist on the sample.
Does anybody know a solution for this ? Thank you in advance!

[Guest]

Dear JK,
plasma etching often result in heavily crosslinked resist structures due to the presence of DUV photons in the system and due to the heat transfer.
If common removers will not work anymore, there are some EKC strippers that still work even with hardly crosslinked resist:
http://www.ekctech.com/remover-business-unit.htm
On the other hand if your substrate will allow treatment with piranha etch at 60?C (H2O2(30%):H2SO4(96%) ratio 1:2) for 10 minutes should also work well.
Good luck

[jk]

Thanks for your tips!
Unfortunately I can't use piranha, that would etch away the uper layer of my sample (GaAs). But I will check the removers you proposed.

[CW]

Dear JK,
I etch silica using an argon plasma & I found that the only way I could remove the resist properly after this process was to use an O2 plasma to break through the top of the fluorinated resist, the resist can then be removed using EKC265.
best regards,
CW

[jk]

Dear CW,

thanks a lot for your message. Unfortunately I cannot use O2 plasma because that would attack the surface of my sample, which is GaAs based.
Regards,
jk

[fermion]

Yes, Also I have a same problem. Firstly I have covered with AZ 5214 pozitive resist on my substrate which is GaN. Then I put into RIE about 25 minutes. After I cleaned it i saw that there is residue resists on my sample.
i tried firstly acetone,and then piranha, HF.Also i made wait my sample 1 day in HF.And later i made O2 plasma. And finally i made CCl2F2 etch plasma.


But residue resist also is on my sample..


What can i do....

Thanks

[MK]

In a previous reply there was a mention about O2-plasma. One needs to specify whether this is a barrel etcher or a RIE process.
After dry etching the top layer of the photoresist often changes of chemistry and becomes difficult to remove even in a barrel-etcher (stripper). Try 1-2 minutes O2-plasma in a RIE machine to remove the top resist layer and then continue the stripping in a barrel etcher (30min). Thsi is tested after Cl2 ans also after CHF3 plasma and it worked.
Another alternative (not tested) is to rinse in acetone after the 1-2min O2-RIE.
Good luck,