[labnetwork] PR bubbles where exposed

[Michael Yakimov]

I guess I am too late to be in first 10 to answer...
N2 forms as a result of photochemical reaction in DNQ resists. You need slower and/or lower exposure to generate less N2 and allow it to dissipate
Last paragraph in this link describes the problem:
https://www.allresist.com/resist-wiki-why-may-air-bubbles-develop-in-photoresist-films-and-how-can-they-be-avoided/
[http://allresist.de/wp-content/themes/regnerbau/img/icons/facebook-logo.jpg]<https://www.allresist.com/resist-wiki-why-may-air-bubbles-develop-in-photoresist-films-and-how-can-they-be-avoided/>
7. Why may air bubbles develop in photoresist films, and how can they be avoided? - Allresist EN<https://www.allresist.com/resist-wiki-why-may-air-bubbles-develop-in-photoresist-films-and-how-can-they-be-avoided/>
Luftbläschen nach dem Aufschleudern sind meist Luftbläschen, z.B. wenn die Lackflasche vor der Beschichtung geschüttelt bzw. stärker bewegt wurde oder der Lack verdünnt wurde. Beschichtungen nach unmittelbarer Öffnung der Flaschen, insbesondere vor einem Temperaturausgleich können ebenfalls zu Luftblasen führen.
www.allresist.com


________________________________
From: labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Maduzia, Joseph Walter <jmaduzi2 at illinois.edu>
Sent: Thursday, November 4, 2021 9:59 AM
To: labnetwork at mtl.mit.edu <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/

[cid:image001.png at 01D7D156.50D75180]<http://illinois.edu/>

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.


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