[labnetwork] PECVD dilute gas question(s)

[Nicholas Menounos]

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<tel:+15089320938>
Office: (617) 253-7234<tel:+16172537234>
Email: Menounos at mit.edu<mailto: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<mailto:labnetwork-bounces at mtl.mit.edu>> on behalf of Nathan Aultman <naultman at creol.ucf.edu<mailto:naultman at creol.ucf.edu>>
Sent: Monday, April 7, 2025 9:49 AM
To: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu> <labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>>
Subject: [labnetwork] PECVD dilute gas question(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<mailto:naultman at creol.ucf.edu>


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