[labnetwork] Mystery White Solid in ICP-CL

[Ryan Rivers]

Yong brings up a good point. Our Cl2 chamber doesn't run CF4, yours does.
It could be polymer as well.

On Wed, Jun 10, 2026 at 5:23 AM Sun, Yong <yong.sun at yale.edu> wrote:

> Hi Emma,
>
> This looks like some kind of fluoropolymer residue (may contain C, F, H,
> O) deposited on the cold ring-area near your ICP ceramic chamber. If you
> look closely, the main etching chamber sidewall doesn't have the same
> residue, suggesting that your main chamber wall is heated??? Maybe there
> are more etching processes that use only RF power (no ICP) recently,
> leading to the fluoropolymer residue accumulated on the cold ring-area near
> the ICP chamber.
>
> If you want to create a more aggressive cleaning recipe after each user
> process, try SF6/O2 instead of CF4/O2, SF6 seems to leave less residue
> behind. The chamber cleaning should be slightly longer than the typical
> user etching process to reduce the accumulation of residue. The following
> is what I do for chamber cleaning in my ICP-RIE that runs both F- and Cl-
> recipes (15min or 30min cleaning):
>
> (i) O2/Ar gentle cleaning: 30mtorr, 50sccm O2, 10sccm Ar, 50W RF, 500W ICP
> -- 2min~5min
> (ii) O2/SF6 deep cleaning: 30mtorr, 50sccm O2, 10sccm SF6, 100W RF, 1500W
> ICP — 5min~10min
> (iii) O2/Ar deep cleaning: 30mtorr, 50sccm  O2, 10sccm Ar, 100W RF, 1500W
> ICP -- 5min~10min
> (iv) O2/Ar gentle cleaning: 30mtorr, 50sccm O2, 10sccm Ar, 50W RF, 500W
> ICP-- 3min~5min
>
> I'd physically clean the chamber whenever users report dusts/white
> powder/defects on their sample. Such residue typically means that, not
> sufficient chamber cleaning has been carried out by certain users in the
> past.
>
> Best,
> Yong Sun
>
> ------------------------------
> *From:* labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Emma
> Anquillare <eanquillare at gc.cuny.edu>
> *Sent:* Tuesday, June 9, 2026 5:59 PM
> *To:* Network Fab <labnetwork at mtl.mit.edu>
> *Subject:* [labnetwork] Mystery White Solid in ICP-CL
>
> Dear LabNetwork Hive Mind,
>
> I went to manually scrub out our ICP-Cl Etcher with IPA as I usually do
> every 1-2 weeks, and opened up the chamber to find large quantities of
> white powder caked along the upper portion of the metal rim near where it
> meets the ceramic liner.  Large amounts of it seemed to have fallen onto
> the table as well. (See Photos). Has anyone ever encountered this? Any idea
> what it might be?
>
> Here are my suspicions and more details:
>
>    1. One of my colleagues commented that it looked like the Aluminum/a
>    she gets in her deposition tools, and I was wondering if something is
>    leeching out of the liner and it needs to be replaced? Might explain why
>    it's concentrated at the border, and appears in such visibly large
>    quantities for a nano-scale etch tool
>    2. The immediate suspect of course is also a solid etch product,  but
>    we have not had any new or unusual materials in the chamber since the last
>    cleaning two weeks ago (or at least, as far as users have told us). We have
>    recently changed our clean recipes so that instead of just a blanket O2
>    clean for everything, there are now customized cleans based on what people
>    are etching, but people seem to be following the rules on this pretty well
>    (see attached). I have also attached a summary of what has been etched in
>    the chamber since the last manual clean and using what gasses.  (We are
>    aware LiNbO3 is not volatile, thus the regular manual cleanings). One thing
>    that also occurred to me was the possibility of LiF formation with
>    increasing amounts of CF4 being run from the new cleans and reacting with
>    sputtered LiNbO3 in the chamber (but again, this seems like an uncannily
>    large quantity of solid for that).
>
>
> I collected some with kapton tape for XPS analysis, but curious to see if
> anyone else has encountered this, especially if it's an issue with the tool
> liner itself.
>
> Thanks!
> Emma
>
>
>
> *_____________________________________________*
> *Emma Anquillare, PhD*
> Research Scientist
> ASRC Nanofabrication Facility
> City University of New York
>
> *Catalyzing Change, Celebrating Gains: *
> *A decade of visionary science for the public good.*
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