[labnetwork] PR bubbles where exposed

[Hollingshead, Dave]

Hi Joe,

The bubbles you are seeing are common, but typically only on thicker SPR-220 coats (~10+µm) that are processed without, or with too short of, a wait time. The samples must rehydrate to complete the photo-reaction. A wait time between exposure and your post-exposure bake usually allows this rehydration to occur.

That being said, I'm guessing your spins are fairly thin with the 4.5 variant so it may be an issue with your cleanroom humidity. If that is particularly low the samples will take longer to rehydrate, or may not rehydrate properly if the humidity is too low.

-Dave

Dave Hollingshead
Manager of Research Operations - Nanotech West Lab
The Ohio State University
Suite 100, 1381 Kinnear Road, Columbus, OH 43212
614.292.1355 Office
hollingshead.19 at osu.edu<mailto:hollingshead.19 at osu.edu> osu.edu<http://osu.edu/>


From: labnetwork <labnetwork-bounces at mtl.mit.edu> On Behalf Of Maduzia, Joseph Walter
Sent: Thursday, November 4, 2021 09:59
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] PR bubbles where exposed

Hello All!

Thank you again for all your feedback on SiO2 etch around Al. It has been very helpful and we are moving down multiple paths suggested via the Lab Network to try to solve the issue. More to come once we solve it!

I have another issue I was hoping for feedback on. We have bubbling in our PR (SPR-220-4.5) (pos tone) that we haven't been able to track the source of. It only bubbles during exposure and only where it is exposed. Unexposed areas are unaffected. I've attached some images of the bubbling where you can see the exposed (lighter) and unexposed (darker) areas. The bubbles are visible to the naked eye. The wafer is silicon w a dry thermally grown SiO2 surface. We typically expose via EV620 mask aligner with Vac+HardContact. However, even in a flood exposure with the mask just set lightly down it still bubbles. Without a mask there are also bubbles randomly distributed across the wafer, but they don't get stuck to the mask so they don't pop. We tried various pre-bakes, HMDS coat vs not, piranha treat vs not. In the past these bubbles show up, we trial and error to get rid of them and suddenly they disappear. Our process, although seemingly repeatable, does not yield repeatable results.

Thank You,
JOE MADUZIA
MNMS Laboratory Specialist

The Grainger College of Engineering
Mechanical Science and Engineering

2239 Sidney Lu Mechanical Engineering Bldg
1206 W. Green
Urbana, IL 61801
217.244.6302 | jmaduzi2 at illinois.edu<mailto:jmaduzi2 at illinois.edu>
https://cleanroom.mechse.illinois.edu/<https://urldefense.com/v3/__https:/cleanroom.mechse.illinois.edu/__;!!KGKeukY!kT5USH9itQ6c35ZM0vr1WvWJcDWY01FqzDHf4aDrhwus1XQwl2UGapNHHk-HnXYYYKeI1Q$>

[cid:image001.png at 01D7D174.0E5A4F10]<https://urldefense.com/v3/__http:/illinois.edu/__;!!KGKeukY!kT5USH9itQ6c35ZM0vr1WvWJcDWY01FqzDHf4aDrhwus1XQwl2UGapNHHk-HnXaR68Z1lw$>

Under the Illinois Freedom of Information Act any written communication to or from university employees regarding university business is a public record and may be subject to public disclosure.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20211104/c6ef1ea5/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 4711 bytes
Desc: image001.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20211104/c6ef1ea5/attachment.png>