[labnetwork] Spot issue in Unaxis-750 PECVD

[N P Vamsi Krishna]

Hi Vibhor,
I agree with the previous responses, I also saw very similar probleam. Sand
blasting the shower head and its pores will resolve your issue.


Thanks & Regards,
vamsi


On Mon, Aug 23, 2021 at 6:38 AM April, Mark R. <mapril at draper.com> wrote:

> 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 <http://www.draper.com/>*
>
>
>
>
>
>
>
> *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
>
>
>
> *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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-- 

___________________________________________________

N.P.  Vamsi Krishna, PhD

*Staff Scientist*

Pritzker School of Molecular Engineering, *The University of Chicago *

*Resident **Associate*

Center for Nanoscale Materials, *Argonne National Laboratory *

Phone: 1 (331) 757-8565
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