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July 1999

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Subject:
From:
nishath yasmeen <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 16 Jul 1999 20:26:32 -0500
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I appreciate you for your input Francis, The non uniformity I mentioned in my previous
mail is within the same PR opening. The current ranges we use are in mAs and we plate at
about 6 to 10 mA/cm2

thanks again,
Yasmeen

Francis Lai wrote:

> 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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