[labnetwork] PECVD dilute gas question(s)

[Phillip Chapman]

If anybody happens to be doing PECVD with <1.37% SiH4, then please let me
know.
I've previously approached vendors about PECVD tools and processes for <1.37%
SiH4, and there didn't seem to be much interest.
I don't think I'm aware of anybody using <2% SiH4.

 Nathan - I'm interested in the responses you receive for my own
education.  There are a lot of research papers, but I don't know that I've
seen a single overall summary on the implications of the different dilutant
gases for all of silicon oxide, silicon nitride, and silicon films
(although it's not clear to me if you intend to try any silicon deposition)
but the dilutant gas does impact film properties and can also influence
other things such as plasma stability and deposition rates.  I've recently
asked a couple of tool vendors this question with a goal of wanting to have
the ability to deposit PECVD SiOx, SiNx, and amorphous poly and they seemed
to lean more towards suggesting silane diluted with argon.

Phil Chapman - Dartmouth College
phillip.f.chapman at dartmouth.edu
or
phillip.chapman83 at gmail.com


On Thu, Apr 10, 2025 at 7:50 AM Nicholas Menounos <menounos at mit.edu> wrote:

> Hi Nathan,
>
>
>
> Reduced code considerations can be significant benefit.
>
>
>
> If you can get <1.37% SiH4 the gas is not governed by CGA G-13.
>
> If you can get below the flammability mixture ranges in CGA P-23 you are
> not flammable.
>
>
>
> Assuming you had good results with 2%, you might find a better use for the
> process gas hardware and associated volume (i.e. MAQ) with an additional
> hazardous gas.
>
>
>
> I can’t speak to the process benefits or research results.
>
>
>
> Best,
>
> *Nicholas Menounos, *PE, LEED AP
>
> Associate Director of Infrastructure
>
>
>
> *MIT.nano*
>
> *Massachusetts Institute of Technology*
>
> 77 Massachusetts Ave, Bldg 12-5007
>
> Cambridge, MA 02139
>
> Cell: (508) 932-0938 <+15089320938>
>
> Office: (617) 253-7234 <+16172537234>
>
> Email: Menounos at mit.edu
>
>
>
> *From:* labnetwork <labnetwork-bounces at mtl.mit.edu> *On Behalf Of *Martin,
> Michael
> *Sent:* Tuesday, April 8, 2025 12:52 PM
> *To:* Nathan Aultman <naultman at creol.ucf.edu>; labnetwork at mtl.mit.edu
> *Subject:* Re: [labnetwork] PECVD dilute gas question(s)
>
>
>
> Hi Nathan,
>
>    We are using 5% SiH4 in Argon.  We switched to this from 100% SiH4 some
> years ago after we had a fire while swapping out a tank.  Our stress and
> other data for nitrides can be found here
> https://louisville.edu/micronano/files/documents/characterization-data/PECVDSiliconNitrideStressControlandRateData.pdf
>
> In essence, it works for us.
>
>
>
> -Michael
> ------------------------------
>
> *From:* labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Nathan
> Aultman <naultman at creol.ucf.edu>
> *Sent:* Monday, April 7, 2025 9:49 AM
> *To:* labnetwork at mtl.mit.edu <labnetwork at mtl.mit.edu>
> *Subject:* [labnetwork] PECVD dilute gas question(s)
>
>
>
> *CAUTION:* This email originated from outside of our organization. Do not
> click links, open attachments, or respond unless you recognize the sender's
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>
> Hello Labnetwork,
>
>
>
> We have a PECVD system using dilute silane (2%)/N2.  Some labs with
> similar systems use dilute silane (5%)/helium.  We are nearing the end of
> our current cylinder and will need a replacement soon.  What are the
> advantages and disadvantages when choosing the dilute gas?  Does choosing a
> helium mixture produce more desirable films and/or quality?  In other
> words, is it worth it to purchase a cylinder with helium?  Also, what would
> be the reason(s) for using helium as an additional process gas?  E.g., a
> separate MFC and gas line.
>
>
>
> Thank you all in advance.
>
>
>
> Nathan C. Aultman
>
> University of Central Florida
>
> 407-823-6852
>
> naultman at creol.ucf.edu
>
>
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