The ring type occurs after some time when coating get started. It will goes away when we reduce the RF power of system. It also make a ring track on AZO target.
What sputtering system are you using? There are systems with rotating magnet systems behind the target, if the rotational frequency matches your observations, that would at least be the explanation for that. It is also normal that you have ring-shaped race tracks on your target, could you maybe add a photo of your post-process target so we can evaluate whether it's a normal or a "bad" kind of track?
The most critical point here from my point of view is the flickering. That indicates that something is unstable about your plasma and something doesn't fit. Do you log the reflected power and can you correlate it to the appearance or disappearance of the phenomenon? That would indicate your matching capacitors are not doing their job right. If you don't have automatic matching, please be aware that the matching capacities are power dependent.
Otherwise it might be that your gas flow is optimized for low power, but isn't good for sustaining high powers.
Thanks Jürgen Weippert for you kind suggestion.
We are using HHV Sputtering system made by HHV Banglore (India). In this system, there are two magnetrons with permanent magents. The tracks are somewhat different and you can see from the attched images.
The reflected power increases when this phenomenon occurs and when we decrease the RF power due to which the ring type phenomenon goes away, reflected power again decreased.
I don't know much about matching capacitor but for minimizing reflected power, both manual and auto operation are there. We will keep it on Auto until it became necessary to adjust the reflected power Manually.
Also, we have tried from lower to higher power i.e. from 200 to 450 W. The phenomenon occurs on every power.
Please see if there are all the answers you expected from my side and guide me further.
OK, it is normal that the race tracks go deep in one location, but the interesting part is that the color top right is the metal color and the rest is brown. That indicates some sort of asymmetry, but maybe the top right section was just the last rotational position in which material was ablated.
The correlation to the reflected power indicates that either the matching system doesn't do its whole job or that something is wrong about the overall process conditions, that's hard to tell.
Something else that bothers me are the holes in the target, that indicates improper manufacturing of the material and can cause misorientations, but I'm not aware of flickering being caused by that (which doesn't mean that it can't be caused this way, I just don't know it).
For sputtering AZO (Al-doped ZnO), because of its relatively high conductivity, you can use DC. You don't need RF at all. I agree with Dr. Weippert that you have a rotating magnet array below the planar target, there must be some form of interference with the RF frequency. My experience is that such technology (RF) gives rise to all kinds of aberrant effects during processing.
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