[labnetwork] Spot issue in Unaxis-750 PECVD

Mon Aug 23 12:32:47 EDT 2021

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

Web: http://mntl.illinois.edu/

On Mon, Aug 23, 2021 at 11:14 AM Vibhor Kumar <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>
> *Sent:* Monday, August 23, 2021 5:48 AM
> *To:* Paolini, Steven <spaolini at cns.fas.harvard.edu>; Vibhor Kumar <
> vk409 at soe.rutgers.edu>; labnetwork at mtl.mit.edu <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
> [image: color_logo_small4]
> * 555 Technology Square*
>
> *Cambridge, MA  02139*
>
> *mapril at draper.com <mapril at draper.com>   *
>
> *O # 617-258-1613 C # 617-455-1596*
>
> *www.draper.com
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>
>
>
>
>
>
>
> *From:* labnetwork <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>; 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
>
> www.cns.fas.harvard.edu
> <https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.cns.fas.harvard.edu%2F&data=04%7C01%7Cvk409%40soe.rutgers.edu%7Cd551b8506f35475f600808d96623847a%7Cb92d2b234d35447093ff69aca6632ffe%7C1%7C0%7C637653125005769879%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=gm9U%2BrOy3WNP7b5et0hNpJaadqxOR1nFlhi%2B5YvUU5Y%3D&reserved=0>
>
>
>
> *From:* labnetwork <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
> *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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