[labnetwork] Experience with BaTiO₃ etching in an ICP-RIE

[Emma Anquillare]

Hello,

Just going over some notes- I think we've also had our deposition tool manager disallow a Barium-related deposition request due to safety concerns as well.

Emma

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

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From: labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Sun, Yong <yong.sun at yale.edu>
Sent: Wednesday, August 5, 2026 12:47 AM
To: Jacob T. Trevino <jt2900 at columbia.edu>; Network Fab <labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] Experience with BaTiO₃ etching in an ICP-RIE


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Hi Jacob,

Etching BaTiO3 with Cl2/Ar can produce BaCl2, which is highly soluble in water and extremely toxic if ingested or absorbed. Soluble barium acts as a muscle toxin that causes severe cardiac arrhythmias, muscle paralysis, and gastrointestinal failure (quote: https://wwwn.cdc.gov/tsp/MMG/MMGDetails.aspx?mmgid=321&toxid=57<https://urldefense.com/v3/__https://wwwn.cdc.gov/tsp/MMG/MMGDetails.aspx?mmgid=321&toxid=57__;!!GIqKXF0_-xZi!rnUAb4ymHNaAaPQrvk92Lpy4I_4Or-y6gkgYL8KkxRYsDN0x1qZhGE9mYfAMjK5INImSFtJSKOPoagu7coZ8iJx33oFDovo$>)

The tool manager will have to be prepared when opening the chamber (or the downstream vacuum line) to perform any service so as not to get poisoned. If this tool is shared with other processes, it's probably not a good idea to introduce BaTiO3. Maybe the specific user should explore other wet etching methods instead.

Best,
Yong Sun
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From: labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Jacob T. Trevino <jt2900 at columbia.edu>
Sent: Tuesday, August 4, 2026 4:05 PM
To: Network Fab <labnetwork at mtl.mit.edu>
Subject: [labnetwork] Experience with BaTiO₃ etching in an ICP-RIE

Hi All,

We are reaching out to see if anyone has experience etching barium titanate (BaTiO₃, BTO) in a ICP-RIE system (our system is an Oxford PlasmaPro 100 Cobra).

One of our users has requested to etch BTO using a Cl₂/Ar plasma. Our primary concern is the potential formation of nonvolatile barium chloride (BaCl₂), which could deposit on chamber surfaces and pose a cross-contamination risk for subsequent users. We're trying to understand whether this is a manageable process or one that should be avoided in a multi-user environment.

I'd be interested in hearing about your experience, including:

  *   Have you processed BTO in a Cl₂/Ar ICP-RIE?
  *   If so, did you observe persistent chamber contamination or evidence of cross-contamination?
  *   Were standard chamber cleaning procedures sufficient to restore the tool?
  *   Did you implement any special qualification, dedicated hardware, or process restrictions?
  *   If you decided against running BTO in a shared chlorine etcher, what was your rationale?

Any insights, lessons learned, or references to published work would be greatly appreciated.

Best,
Jacob

PS: So good to see many of you at UGIM!

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Jacob Trevino, PhD
Senior Director, Columbia Nano Initiative Labs
Columbia University
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