[labnetwork] What is this??

[Lavendra Yadav Mandyam]

Hi Emma,

The issue is a combination of polymer coating and window etching. Oxford makes these viewports out of quartz which reacts with SF6 and etches over time, causing to become cloudy/hazy. This shouldn’t affect your process; you just won’t be able to see the wafer clearly anymore.

These viewports come with the PM kit and will be replaced. If you don’t have PM scheduled, you can buy them directly from Oxford and replace them yourself, it is very straight forward. Just make sure you have the O-ring too.

Alternatively, you can have a custom view port made out of sapphire. It last very long but is quite pricy. Another trick to coat a thin Al2O3 with ALD before installation. This provides a AlF protection against SF6 and last fairly long.


Best regards,

Lavendra Mandyam

Senior Process Engineer – Dry Etching

Stanford Nanofabrication Facility

Paul G. Allen Building

420 Via Palou Mall

Stanford, CA 94305

Phone: (650) 498-1304

https://snf.stanford.edu/

lavendra at stanford.edu<mailto:lavendra at stanford.edu>



On Thu, Apr 16, 2026 at 4:40 PM Emma Anquillare <eanquillare at gc.cuny.edu> wrote:

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

[https://mail.google.com/mail/u/0/?ui=2&ik=e7c84bd0ae&attid=0.0.1&permmsgid=msg-f%3A1862672390532151451&permmsgid=msg-f%3A1862672390532151451&th=19d98aab9a98b89b&view=fimg&fur=ip&sz=s0-l75-ft&attbid=ANGjdJ_dafCqoXn4JmsFxrHjyJ-7VbtECy5gYLiTGPQt68iByCxiKlvUPyDIP7beF30SQih7OFAvFlno0Jn-YByHnhx5wpBvDMwok46QxcB7ohZ0bOMKpgteT5976R0&disp=emb&zw]
Catalyzing Change, Celebrating Gains:
A decade of visionary science for the public good.
_______________________________________________
labnetwork mailing list
labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
https://mtl.mit.edu/mailman/listinfo.cgi/labnetwork

Best regards,
Lavendra Mandyam
Senior Process Engineer – Dry Etching
Stanford Nanofabrication Facility
Paul G. Allen Building
420 Via Palou Mall
Stanford, CA 94305
Phone: (650) 498-1304
https://snf.stanford.edu/
lavendra at stanford.edu<mailto:lavendra at stanford.edu>


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20260417/7c04c206/attachment.html>