[labnetwork] Spot issue in Unaxis-750 PECVD

[Vibhor Kumar]

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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