[labnetwork] Predicting Solid Etch Products

Thu May 16 14:52:20 EDT 2024

Hi all,

Lots of great information here!

In Valutek's 35+ years of experience servicing the controlled environment needs for thousands of organizations in advanced material and academia, we've seen a lot of different cleaning strategies.

If contamination isn't an issue on an initial clean, we've observed clients using heavy duty scour pads, or really abrasive sponges. Something like Scotch-Brite or a grid sponge. That's typically when the component is being taken out of the chamber. Other options for remote cleaning outside the chamber are an ultrasonic tank where components are immersed into heated cleaning fluid and agitated through vibration, or bead blasting to clean, deburr or texture wafers and other delicate components. These cleaning techniques are most commonly done by an outside parts cleaning vendor, but are very effective in cleaning stubborn particulates.

For any cleaning being done in-chamber, we recommend a standard weight polyester wiper with an interlock weave. Polyester is low in particulates and extractables, high in durability and strength and is recommended for the removal of dry particulates and contaminants. The standard weight polyester weave has a grid with a diagonal pattern and because of this texture it has an increased ability to retain cleaning solution. Polyester is perfectly suited for ultra-clean environments.

Based on our experience, the most common chemistry solution for cleaning inside the chamber is 70% IPA and 30% DI water. Although, we do have some clients with a process that's sensitive to water who use 100% IPA wipers. The problem with mixing a wiper with 100% alcohol is that it will evaporate really quickly. The dwell time is much higher when cut with 30% water. Valutek has made 100%, 99%, 90%, 70%, 50%, 10%, 6%, etc. etc. IPA wipers – all depending on specific applications.

If you're interested in receiving a free sample of our prewetted wiper based upon your own IPA chemistry choice, we'd be happy to provide that for your evaluation.

Best,

Andi Batchelor

Customer Advocate

VALUTEK

[A colorful squares with white text  Description automatically generated]

[phone phone-icon]602.256.0540

[Email email-icon] abatchelor at valutek.com
[website website-icon]  www.valutek.com <https://www.valutek.com/>

[BLOG]<https://pages.valutek.com/blog>[CATALOG]<https://pages.valutek.com/catalog>

[iest-corporate-members]<https://www.iest.org/About-IEST/Corporate-Sponsors> [linkedin] <https://www.linkedin.com/company/valutek/>  [X] <https://twitter.com/valutek>  [youtube] <https://www.youtube.com/channel/UCJkCsJOTxp_YSXc3s_SgWwg>

________________________________
From: labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Sam Azadi <azadi at seas.upenn.edu>
Sent: Wednesday, May 15, 2024 7:22 AM
To: Wirth, Justin C <jcwirth at purdue.edu>
Cc: labnetwork at mtl.mit.edu <labnetwork at mtl.mit.edu>; Emma Anquillare <eanquillare at gc.cuny.edu>
Subject: Re: [labnetwork] Predicting Solid Etch Products

CAUTION: This email originated from outside of Valutek, Inc. Do not click links or open attachments unless you recognize the sender and know the content is safe.

Hi Emma,

To see what compounds I may have in the chamber, I use the "compounds" section of this link: https://ptable.com/#Compounds
You can just drag and drop the primary elements in the box in the middle, and on the left you'll see a list of all possible and known compounds that have the selected elements. You can start by looking at the boiling point of the ones that may exist inside the chamber, and as Justin said, as a rule of thumb consider the ones with Tbp < 185 C as volatile.

SA

On Wed, May 15, 2024 at 7:53 AM Wirth, Justin C <jcwirth at purdue.edu<mailto:jcwirth at purdue.edu>> wrote:

Hi Emma,

This is a very good question, and one that I’ve struggled to answer as well. I’m not an etch expert but by necessity have had to try to answer some of these questions, and this<https://urldefense.com/v3/__https://purdue.atlassian.net/wiki/spaces/BNCWiki/pages/6246876/Tutorial*on*Etching*TutorialonEtching-GeneralMaterials-Willitetch*3F__;KysjJQ!!IBzWLUs!TANTwddpDwOfbj22F_YUpJEtqvljiVHzw7Z1iLBNvvrYiTz08eoNY0T9ifutauC6eyGzMMW23dZa00RKLcLjUQ$> (reproduced below, not sure if it will come through or not) is a very rough starting point I’ve come up with that I think (hope) helps get in the ballpark. Would love to hear from other folks as to how they approach this.

Materials can generally be etched in the RIEs as long as they form volatile byproducts, or products for which the vapor pressure (at the temperature of the etch) is higher than the pressure of the chamber.

Etching is very complicated and this will be massive oversimplification...but generally volatile byproducts can be determined from literature, or as a fallback, the CRC Handbook of Chemistry and Physics Online, (4) Properties of the Elements & Inorganics, Physical Constants of Inorganic Compounds: https://hbcp.chemnetbase.com/faces/documents/04_02/04_02_0001.xhtml<https://urldefense.com/v3/__https://hbcp.chemnetbase.com/faces/documents/04_02/04_02_0001.xhtml__;!!IBzWLUs!TANTwddpDwOfbj22F_YUpJEtqvljiVHzw7Z1iLBNvvrYiTz08eoNY0T9ifutauC6eyGzMMW23dZa00S9rICseA$>. From there, click "Go to Interactive Table", and find products that may be formed (i.e. chloride, fluorides, oxides, depending on the gasses). A compound is deemed volatile if it has a boiling point at a reasonable temperature range for the temperature and pressure of the system. Note that at lower pressures, boiling points decrease, so these are just a good starting point reference.

As a VERY general rule of thumb, anything with a boiling point (tbp) < 185 C will be volatile in the ICP RIEs.

As an example, aluminum chloride is volatile, and aluminum fluoride and aluminum are not.

[cid:ii_18f7c99e0fe5b16b22]

[cid:ii_18f7c99e0fe692e333]

[cid:ii_18f7c99e0fe7745b44]

[cid:ii_18f7c99e0ff855d355]

Neither Copper chloride or copper fluoride is volatile, which is why it is not allowed in any chamber:

[cid:ii_18f7c99e0ff9374b66]

[cid:ii_18f7c99e0ffa18c377]

[cid:ii_18f7c99e0ffafa3b88]

[cid:ii_18f7c99e0ffbdbb399]

[cid:ii_18f7c99e0ff1f3c04fa]

[cid:ii_18f7c99e0ff201d7d0b]

Byproducts of silicon are very volatile:

[cid:ii_18f7c99e0ff20fef51c]

[cid:ii_18f7c99e0ff21e06d2d]

Many times different fluorides/chlorides of the same material will have drastically different boiling points. It's important to research which will be formed in the plasma. Titanium is a good example of this, with TiCl2  and TiCl3 being non-volatile, and TiCl4 being volatile:

[cid:ii_18f7c99e0ff22c1e53e]

[cid:ii_18f7c99e0ff23a35d4f]

[cid:ii_18f7c99e0ff2484d5510]

Thanks,

Justin

Justin C. Wirth, PhD

Senior Research Engineer – EBL Processes & Nanofab Process Consultation

Birck Nanotechnology Center | Room 2287A
765.494.8203 | jcwirth at purdue.edu<mailto:jcwirth at purdue.edu>

BNCWiki<https://urldefense.com/v3/__https://purdue.atlassian.net/wiki/spaces/BNCWiki__;!!IBzWLUs!TANTwddpDwOfbj22F_YUpJEtqvljiVHzw7Z1iLBNvvrYiTz08eoNY0T9ifutauC6eyGzMMW23dZa00SOT9T6ag$> | Purdue iLab<https://urldefense.com/v3/__https://purdue.ilabsolutions.com/__;!!IBzWLUs!TANTwddpDwOfbj22F_YUpJEtqvljiVHzw7Z1iLBNvvrYiTz08eoNY0T9ifutauC6eyGzMMW23dZa00T7I8wVQg$> | Book time on my calendar<https://urldefense.com/v3/__https://outlook.office.com/bookwithme/user/5ad94572a9c04a4e8aa9159479128868@purdue.edu?anonymous&ep=plink__;!!IBzWLUs!TANTwddpDwOfbj22F_YUpJEtqvljiVHzw7Z1iLBNvvrYiTz08eoNY0T9ifutauC6eyGzMMW23dZa00Tyx7nbGQ$>

From: labnetwork <labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>> On Behalf Of Emma Anquillare
Sent: Friday, May 10, 2024 12:07 PM
To: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: [labnetwork] Predicting Solid Etch Products

You don't often get email from eanquillare at gc.cuny.edu<mailto:eanquillare at gc.cuny.edu>. Learn why this is important<https://urldefense.com/v3/__https://aka.ms/LearnAboutSenderIdentification__;!!IBzWLUs!TANTwddpDwOfbj22F_YUpJEtqvljiVHzw7Z1iLBNvvrYiTz08eoNY0T9ifutauC6eyGzMMW23dZa00RjgrJ9kQ$>

---- External Email: Use caution with attachments, links, or sharing data ----

Dear Lab network,

First time caller here 😊

I am new to plasma etching, and working to institute better process control in our ICP and RIE etchers in an academic shared use facility. We don’t have the capacity to designate a single etcher for each process, so between our three tools, we essentially have a most-restricted, somewhat restricted, and “dirty” tool. To avoid cross contamination and chamber residue buildup, we have a technician manually scrub out the chambers with IPA every week- usually seeing the most solid residue in our ICP that handles Lithium Niobate milling.

My question is- while many products of etch reactions get pumped away as vapors, what about the reactions that do leave solid residues? Is there a systematic way to predict or look up what solids will be left from common (or unusual) reactions, and know how they will react and interact with other solids and gasses present in your chamber? Especially with such frequent manual cleaning, how do you ensure that you don’t inadvertently open the chamber to something acutely toxic, pyrophoric, shock sensitive, etc?

Very curious to learn what steps people take and tools they use (literature? calculations? databases? forums?)  when approaching this problem, and when asked to allow a new material into a tool.

Best,

Emma

_____________________________________________

Emma Anquillare, PhD

Research Scientist

ASRC Nanofabrication Facility

City University of New York

[cid:ii_18f7c99e0fe4ce8e91]

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://urldefense.com/v3/__https://mtl.mit.edu/mailman/listinfo.cgi/labnetwork__;!!IBzWLUs!TANTwddpDwOfbj22F_YUpJEtqvljiVHzw7Z1iLBNvvrYiTz08eoNY0T9ifutauC6eyGzMMW23dZa00Sz0F4lnw$

--
Mohsen (Sam) Azadi
Principal Scientist
Quattrone Nanofabrication Facility
Singh Center for Nanotechnology
University of Pennsylvania
3205 Walnut St. Room 116
Philadelphia, PA 19104
-------------------------------------
Pronouns: he/him/his
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 141606 bytes
Desc: image001.jpg
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.png
Type: image/png
Size: 10436 bytes
Desc: image002.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image003.png
Type: image/png
Size: 11185 bytes
Desc: image003.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0001.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image004.png
Type: image/png
Size: 9552 bytes
Desc: image004.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0002.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image005.png
Type: image/png
Size: 9109 bytes
Desc: image005.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0003.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image006.png
Type: image/png
Size: 8407 bytes
Desc: image006.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0004.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image007.png
Type: image/png
Size: 10144 bytes
Desc: image007.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0005.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image008.png
Type: image/png
Size: 8057 bytes
Desc: image008.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0006.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image009.png
Type: image/png
Size: 8693 bytes
Desc: image009.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0007.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image010.png
Type: image/png
Size: 8631 bytes
Desc: image010.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0008.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image011.png
Type: image/png
Size: 9702 bytes
Desc: image011.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0009.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image012.png
Type: image/png
Size: 9804 bytes
Desc: image012.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0010.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image013.png
Type: image/png
Size: 8875 bytes
Desc: image013.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0011.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image014.png
Type: image/png
Size: 9844 bytes
Desc: image014.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0012.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image015.png
Type: image/png
Size: 9531 bytes
Desc: image015.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0013.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image016.png
Type: image/png
Size: 9762 bytes
Desc: image016.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20240516/6cf841f0/attachment-0014.png>