hello,

current density comes from Cu ions moving from Cu electrode, so keeping
current density same and coating slowly is contradictory. I guess you may
have to make the solution acidic where the current flow will be more and
make lighter solution of Copper sulphate. But what happens to Si layer with
acidic solution we have to think... I guess it is not possible.

    You reduce the current density !  What is the reason?  Why don't you want to
reduce the current density?

Dilute solution is the best alternative for this.

Nabhiraj

On Wed, Oct 27, 2010 at 3:21 AM, Mingke Xiong  wrote:

> Hi, dear all,
>
> I am doing copper electroplating on silver seed layer. Since the silver
> seed layer is very thin, thus with high resistance, we need 2 ~ 3 minutes of
> copper plating with high current density (5 Amps) in order to quickly cover
> the whole surface area of the sample before we can reduce the current (1
> Amps) for a more uniform plating. However, we just need a very thin layer of
> copper. The plating rate is too high during the high current density period
> that makes it very hard to control the thickness of copper film.
>
> I am just wondering if anyone have any idea how to reduce the copper
> plating rate without reducing current density.
>
> Any suggestion is sincerely appreciated.
>
> Regards,
>
> Mingke