[labnetwork] Strange "sample memory" with LOR 5B

[Martin, Michael]

We actually made a TikTok about this subject recently that went somewhat viral.  Despite the off-color humor it seems relevant to the discussion https://www.tiktok.com/@micronanolouisville/video/7214338192995061034  These wafers were cleaned in a 60C NMP bath and it was clear that the HMDS was still on the surface.

________________________________
From: labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Cohen, Ana N CTR USARMY DEVCOM ARL (USA) <ana.n.cohen.ctr at army.mil>
Sent: Tuesday, March 28, 2023 6:40 PM
To: labnetwork at mtl.mit.edu <labnetwork at mtl.mit.edu>; Gustavo de Oliveira Luiz <deolivei at ualberta.ca>
Subject: Re: [labnetwork] Strange "sample memory" with LOR 5B

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Michael got me thinking... Gustavo, could you confirm the DI water rinse
after the piranha looks as you'd expect? I'm not 100% certain the chemistry,
but since HMDS is more a surface treatment than a residue remaining on the
wafer I'm curious if it actually could be unaffected.

I have definitely seen this 'ghosting' after I solvent strip a patterned
wafer and then need to rinse with DI water. Any water collected on the wafer
surface would match wherever resist had previously been, presumably due to
remaining HMDS. I've not seen it impact further patterning before, but I've
also not used the LOR in my tests and may also have run less tests per
wafer. I'd actually found the following information from EPFL on reworking
HMDS-treated wafers a little while ago when testing out our lab's HMDS
quality (don't know who over there figured this out, but thanks to whoever
did!)
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.epfl.ch%2Fresearch%2Ffacilities%2Fcmi%2Fprocess%2Fphotolithography%2Fhmds-ap&data=05%7C01%7Cmichael.martin%40louisville.EDU%7C1eb5be3d74d4448b451008db301b632d%7Cdd246e4a54344e158ae391ad9797b209%7C0%7C0%7C638156666427001449%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=eTd2IROmftQa49qtYImK3w7CZVOBRwfw2tr9ncJOn%2BI%3D&reserved=0
plication/

Either way, the O2 plasma during the cleaning process should be worth a
shot!

--
Ana N. Cohen [she/her/hers]
Photolithography Cleanroom Technician
Contractor | General Technical Services, LLC
US Army Research Laboratory
2800 Powder Mill Road, Adelphi, MD 20783
Tel: 301-394-1527
Email: ana.n.cohen.ctr at army.mil

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