nishath yasmeen wrote:

> We are seeing non uniform plated copper deposits in very small areas on
> silicon wafers from the acid copper plating bath.
>
> I can understand the non uniformity across areas which are large (
> inches) but these areas measure in micron range. The thickness profile
> of this area looks like a staircase on the profilometer.  Is this a flow
> problem? Does this depend on the current density?
> What other factors do I need to consider for uniformity improvement?
>
> Any suggestions will be greatly appreciated.
> Thanks,
> Yasmeen
>
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Dear Yasmeen:

I would regard your case as pattern plating. In pattern plating, the current densities
on each area vary. Smaller area will take more current and plate more while lager area
will take less current and plate less. I suggest you to use current density of 10
mA/cm**2. If you are plating areas measuring in microns, you need a power supply which
can provide currents in mA for the acid plating bath.

Please correct me if I am wrong!!!!!

Francis

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