[labnetwork] Spot issue in Unaxis-750 PECVD

Tue Aug 24 11:18:04 EDT 2021

Thanks again, Everyone!
Glad to have such unmatched support from Labnetwork community.

Sincerely,
-Vibhor-

________________________________
From: Lavendra <lavathedon at gmail.com>
Sent: Monday, August 23, 2021 11:32 AM
To: Vibhor Kumar <vk409 at soe.rutgers.edu>
Cc: labnetwork at mtl.mit.edu <labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] Spot issue in Unaxis-750 PECVD

Hi Vibhor,

Adding one more possibility to the previous comments,
showerhead holes get etched and expand in the long run, even the tiniest changes in these holes can cause these patterned spots (usually in the center area). By changing the showerhead can solve this issue, if not you can change the process (without change in RI) with DOE in reducing Silane flow and reducing RF power.
Goodluck

Best,

Lavendra Mandyam

Research Engineer

Nick Holonyak, Jr. Micro and Nanotechnology Laboratory

University of Illinois at Urbana-Champaign

Rm 2300, MC-249

208 North Wright Street | Urbana, IL 61801

Phone (217)300-4639 | fax: 217 244 6375

Email  Lavendra at illinois.edu<mailto:Lavendra at illinois.edu>

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[X]

On Mon, Aug 23, 2021 at 11:14 AM Vibhor Kumar <vk409 at soe.rutgers.edu<mailto:vk409 at soe.rutgers.edu>> wrote:
Thank you everyone for sharing your experience!
Let me long purge the silane line to eliminate any dust and clean the shower head thoroughly.

Sincerely,
-Vibhor-

________________________________
From: April, Mark R. <mapril at draper.com<mailto:mapril at draper.com>>
Sent: Monday, August 23, 2021 5:48 AM
To: Paolini, Steven <spaolini at cns.fas.harvard.edu<mailto:spaolini at cns.fas.harvard.edu>>; Vibhor Kumar <vk409 at soe.rutgers.edu<mailto:vk409 at soe.rutgers.edu>>; labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu> <labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>>
Subject: RE: Spot issue in Unaxis-750 PECVD

Good Morning Vibhor,

I concur with Mr. Paolini.  I had a similar issue on a PECVD tool.  After a thorough shower head clean, including the diffuser plate, the shower head pattern was eliminated.  This routinely gets done each year now, during a major PM.  You may need to perform more due to your usage.

Hope this helps.

Mark R. April
Senior  Equipment Engineer

Microfabrication Laboratory
[color_logo_small4]
555 Technology Square

Cambridge, MA  02139

mapril at draper.com<mailto:mapril at draper.com>

O # 617-258-1613 C # 617-455-1596

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From: labnetwork <labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>> On Behalf Of Paolini, Steven
Sent: Friday, August 20, 2021 4:02 PM
To: Vibhor Kumar <vk409 at soe.rutgers.edu<mailto:vk409 at soe.rutgers.edu>>; labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] Spot issue in Unaxis-750 PECVD

Vibhor,

  You are most likely seeing the effect of the showerhead being in need of cleaning, particularly the backside. The Deposition of dielectric films creates a powdery substance just outside of the intended plasma concentrate. This debris, over time, will allow small reactions to happen under the showerhead and show up as spots on your wafer, most likely in the pattern of the holes in the showerhead. I would suggest removing the showerhead and diffuser plate and performing a very thorough clean on all the parts. In my experience, and depending on the usage, this should be performed routinely at an interval that keeps the effect at bay.

  Hope this helps,

    Steve Paolini

   Equipment Dood

Steve Paolini

Principal Equipment Engineer

Harvard University Center for Nanoscale Systems

11 Oxford St.

Cambridge, MA 02138

617- 496- 9816

spaolini at cns.fas.harvard.edu<mailto:spaolini at cns.fas.harvard.edu>

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From: labnetwork <labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>> On Behalf Of Vibhor Kumar
Sent: Friday, August 20, 2021 1:49 PM
To: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: [labnetwork] Spot issue in Unaxis-750 PECVD

Hello Everyone,

During nitride/oxide deposition with Unaxis-750 PECVD, we are getting a mirror image of shower head on the wafer, i.e., spots. We cleaned the chamber with CF4 for 2 consecutive days, each day 4:30 hrs. The conditions were

CF4 = 100 sccm, Temp = 250 C, chamber pressure = 600 mT, time = 4:30 hrs

We also evacuated the silane gas line, but there is no leakage.

After completing the cleaning, when we conditioned the chamber and deposited nitride, the spots were lightened. But on the second day, the spots look enlarging again.

Can anyone please suggest solution to this issue?

Thanks,

-Vibhor Kumar-

Postdoctoral Associate

Rutgers, The State University of New Jersey.

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