[labnetwork] Photoresist and Ebeam Resist In Same Spinner?

[Massey, Travis]

Hi Grant,

LLNL has seen clogs in the drain line before from users mistakenly running LOR and i-line PR (novolak) in the same bowl.  SU-8 gets one spinner, LOR and polyimide have another (NMP-soluble but acetone-incompatible), and our novolaks in their own.

We've not had problems with AR-N 7520, CSAR, and PMMA/MMA in the same spinner as our novolaks, but we also fastidiously foil-line our bowls with each use.  We've also been spinning very small amounts of HSQ on the foil-lined novolak resist spinner, and all of this HSQ is caught on the foil.

When any resist does get past the foil, we recommend our users dry wipe first to remove 99.9%, then solvent wipe (with the appropriate solvent) to clear the 0.1% residue, as well as any particles left behind by the dry tech wipe.  For the polyimide spinners, we use alpha wipes (more expensive, but leave absolutely no particles), because polyimide can't be reworked nearly as easily as photoresist if a particle gets in.  Everyone needs to leave the bowl pristine when they're done.

On our spin track, we do restrict which resists can be installed, since that bowl doesn't get lined or frequently cleaned.  However, that track is primarily for our i-line positive novolaks. The one exception is nLOF 20xx (negative photoresist), but nLOF is soluble in acetone, so this was a conscious exception to the "don't mix positive and negative" rule, and it has been fine.  Most tracks expect 1 gallon (or 4L) bottles, so this tends to exclude e-beam resists anyway, unless your users and manually dispensing on the track.

The bottom line is, as others have said, you can and probably already do plan around what solvates or crosslinks each resist, but for the small amounts of resist common for e-beam, careful foil lining can buy you a lot of leeway in bending the rule.

Best,
Travis

From: labnetwork <labnetwork-bounces at mtl.mit.edu> On Behalf Of Yakimov, Michael
Sent: Wednesday, February 19, 2025 9:34 AM
To: Virgínia Soares <vsoares at inesc-mn.pt>; 'Grant Shao' <shaog at stanford.edu>; labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] Photoresist and Ebeam Resist In Same Spinner?

I would expect something along the lines of stuff precipitation in the drain. Common novolak resists use pgema or lactate solvent, usually supplemented with acetone and ipa are cross compatible, and may dry but not precipitate.
SU8 is developed - aka soluble - in pgema, but not soluble in acetone as far as I remember.
With ebeam resists and-or spin-on glass chemistry is very different and more diverse. Small quantities and wiping the bowl may help with drainage maybe?

Thanks

Mike



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From: labnetwork <labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>> on behalf of Virgínia Soares <vsoares at inesc-mn.pt<mailto:vsoares at inesc-mn.pt>>
Sent: Wednesday, February 19, 2025 8:24:55 AM
To: 'Grant Shao' <shaog at stanford.edu<mailto:shaog at stanford.edu>>; labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu> <labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>>
Subject: Re: [labnetwork] Photoresist and Ebeam Resist In Same Spinner?


Dear Grant,



I our lab we use the same spinner for photo and e beam resist, though I am not sure it should be done as we were buying a new resist track and the supplier told us we should not mix negative resists (like most of our e-beam resists) with positive resists. Something about it being hard to clean as you cannot use the same solvents and that it would end up clogging the lines. That wasn't for a manual spinner mind you.



Melhores Cumprimentos/Best Regards





Virginia Soares

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From: labnetwork <labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>> On Behalf Of Grant Shao
Sent: 19 de fevereiro de 2025 02:27
To: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: [labnetwork] Photoresist and Ebeam Resist In Same Spinner?



Hello Labnetwork,



I'm wondering if there's a chemical reason for having dedicated spinners to keep photoresist and ebeam resist separated. I think quite a few of the university nanofabs do this, but wondering what the rationale is. Is there some sort of chemical reaction that makes it more likely to contaminate or harder to clean up?



Thanks,

Grant



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Nanofabrication Operations Manager

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