[labnetwork] What is this??

[Lino Eugene]

Hi Emma,

It looks that you had some fluoropolymer flakes due to the passivation with C4F8 during Bosch process. There are likely seen after long runs of Bosch or pseudo-Bosch etch or with unoptimized passivation steps. You can see fluoropolymer on the quartz clamp as well. With time, the inner side of the viewport becomes rough as well as it is slowly etched. A standard viewport is made of borosilicate glass if I am not mistaken and is replaced as part of a preventive maintenance every year. You can opt for a sapphire window that should stay transparent longer, but it is more expensive.

Best,

Lino Eugene, P.Eng., Ph.D.,
Micro/nanofabrication process engineer
Quantum-Nano Fabrication and Characterization Facility
Office of Research
QNC 1611
University of Waterloo
200 University Avenue West
Waterloo, ON, Canada
N2L 3G1

Ph: +1 519-888-4567 #37788
Cell: +1 226-929-1685
Websites:
https://uwaterloo.ca/quantum-nano-fabrication-and-characterization-facility/
https://fab.qnc.uwaterloo.ca/

De : labnetwork <labnetwork-bounces at mtl.mit.edu> De la part de Emma Anquillare
Envoyé : 15 avril 2026 21:38
À : Network Fab <labnetwork at mtl.mit.edu>
Objet : [labnetwork] What is this??


Dear LabNetwork,

I humbly call upon your mighty wisdom! A few weeks ago I noticed what (I thought) was some kind of polymer gunk or residue on the interior of our ICP-F porthole window. (See images attached). We have been running a DRIE/Bosch process every few months, so despite manual cleans before and after each session it didn't seem too remote that polymer residue could build up on the porthole, which is usually not scrubbed.

However, when I went to get rid of it during my monthly manual clean of the tool, it wouldn't go away. I tried rubbing it with IPA on a lab wipe, as well as scratching at it more forcefully with IPA-soaked swabs, and even scratching with the rear plastic part of the swab. It appeared to go away at first when wet, but once the IPA evaporated, I could see I hadn't actually removed anything. My manual scrubs are also followed by a lengthy hour-and-a-half dry clean (O2-50, SF6- 10, 10mT, 20 C, RF- 100W, ICP- 2500 W) that users also use for a shorter period after each session. I've been managing this tool for about two years now and never seen anything like this.

Does anyone know what it is, if it's a concern, and if/how I should remove it?

Thanks!
Emma
_____________________________________________
Emma Anquillare, PhD
Research Scientist
ASRC Nanofabrication Facility
City University of New York

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