[labnetwork] Liquid Appearing in ICP Cl Chamber?!

Sat Oct 10 09:52:14 EDT 2026

Emma,

A more thorough answer:
What looks like condensation is hygroscopic chloride residue doing it. With
conventional positive-pressure delivery you inevitably leave trace chloride
salts (CaCl2, MgCl2, NaCl etc from prior moisture/hydrolysis) in
regulators, pigtails, and dead legs and especially around and under o-ring
seal crevices. Many of those salts are deliquescent at normal lab RH
(40-60%), so they pull water vapor from the air and form a brine film. That
film can then hydrolyze any residual Cl2 to HCl/HOCl, which keeps the spot
wet and makes it look like it’s growing.
When the other respondent moved to sub-atmospheric delivery, that visual
“condensation” went away. The mechanism isn’t that the gas changed — it’s
that they reduced the seed: no positive pressure pushing trace gas into
dead volume, much more complete purge, and less salt residue to act as a
moisture pump / condensation nuclei.

A full bake/purge and replacing any elastomer seats that have seen moisture
usually clears it. I would recommend pulling those o-rings and flushing the
chlorine salts with urgency. When we’d leave it to stabilize we noted
pitting of the chamber’s o-ring grooves which leaves additional surface
area and sites to fuel future nucleation sites.

Dr. Michael T. Khbeis
(C)1-443-254-5192
mtkhbeis at gmail.com

On Sat, Oct 10, 2026 at 6:26 AM Michael Khbeis <mtkhbeis at gmail.com> wrote:

> Emma,
>
> Apart from ensuring you don’t have a chiller loop causing physical
> condensation, chlorine residues are generally hydroscopic and will pull
> water right from the air and form the HCl that you measured the pH of.
>
>
> Dr. Michael T. Khbeis
> (C)1-443-254-5192
> mtkhbeis at gmail.com
>
> On Fri, Oct 9, 2026 at 2:12 PM Martin, Michael <
> michael.martin at louisville.edu> wrote:
>
>> Hi Emma,
>>    The only time we've had liquid in our etcher is when we were using
>> Bcl3 delivered at around atmospheric pressure.  We now run it
>> sub-atmospheric and have no problems.
>>
>>   Curious to know how you guys are doing the digital log book.  Is this
>> just an Excell sheet?  Is it part of PTIQ?  I would love to transition to
>> something like this as opposed to paper based logs but fear that we would
>> have even worse compliance than we already do.
>>
>> -Michael
>> ------------------------------
>> *From:* labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Emma
>> Anquillare <eanquillare at gc.cuny.edu>
>> *Sent:* Thursday, October 8, 2026 5:16 PM
>> *To:* labnetwork <labnetwork at mtl.mit.edu>
>> *Subject:* [labnetwork] Liquid Appearing in ICP Cl Chamber?!
>>
>>
>> *CAUTION:* This email originated from outside of our organization. Do
>> not click links, open attachments, or respond unless you recognize the
>> sender's email address and know the contents are safe.
>> Dear Wise Lab Network Oracle,
>>
>> I already shared this with a few tool managers and so far no one else has
>> ever run into it, but maybe someone on here has:
>>
>>
>> Last week I went to vent and wet clean our ICP-Cl etcher. Our tool can
>> only vent using Nitrogen, but I had recently become aware that it's
>> considered a good practice to also then vent to atmosphere, so that if
>> there are residues in the chamber that may react with atmospheric moisture
>> to form HCl/HF vapors they can react fully and be pumped away before the
>> chamber is opened. We don't have this capability, but to compensate I had
>> started letting the tool sit in atmosphere for about an hour so (with a
>> sign telling people to avoid the immediate area) so that even if any of
>> these compounds had been present in unnoticeably small quantities, they
>> could degas before I scrub it (wearing a full face respirator- we don't
>> have a snorkel or air scrubber. That said, other technicians have
>> previously been around this open chamber for days without a respirator and
>> never mentioned any vapors or compounds.) The first time I added the hour
>> wait, I did not notice anything unusual.
>>
>> The last two times I opened the chamber, I've noticed small quantities of
>> white solid on the lower crease of the metal rim. It's there when I first
>> open the chamber, but then significantly reduces or disappears all together
>> by the time the hour is up, so clearly it is reacting with something in the
>> atmosphere. We have had white residue in the chamber before that XPS
>> indicated was likely a fluoropolymer, but this has a very different look to
>> it, and a fluoropolymer would not be so reactive (see attached photos).
>>
>> Then, last time I went to clean the chamber, I came back after the hour
>> in atmosphere to find not only had the white stuff reacted away, but liquid
>> droplets had now formed on the metal ring beneath the liner a few inches
>> away (See photos- though the entire metal ring appeared to also have a
>> sheen to it- so I'm not sure if this was related or something new). The
>> liquid was highly acidic (pH strip 0-1) , so we adjusted our clean to first
>> wipe with a dry wipe, then water, and then only finished with IPA. The tool
>> took longer than usual to pump down again (water on the O-ring?) but the
>> next day it passed leak-up rate no problem.
>>
>> Has anyone ever encountered a liquid in the chamber upon atmospheric
>> exposure? (or ever?) Any idea what any of this might be? (A recent clip of
>> the log is attached- though the 'element soup' method quickly turns into a
>> very large number of potential compounds ). More importantly, If this
>> happened to you, how might you adjust your safety and PPE practices
>> accordingly?
>>
>>
>> Thanks!
>>
>> (PS- A few years ago I shared our SOP for chamber wet cleans and
>> mentioned using acid gloves. I recently realized IPA actually breaks
>> through trionics fairly quickly (~25min), so for PPE I have now been using
>> nitrile gloves on top of acid gloves, which seems effective.)
>> *_____________________________________________*
>> *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.*
>> _______________________________________________
>> labnetwork mailing list
>> labnetwork at mtl.mit.edu
>> https://mtl.mit.edu/mailman/listinfo.cgi/labnetwork
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20261010/b25c18f8/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 141606 bytes
Desc: not available
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20261010/b25c18f8/attachment.png>