>     On top of gold, there is an electroplated and patterned copper layer.
>     I want to remove the exposed gold, but not the copper.
>     I doubt that I can use lift-off technology though.
>     That is why I want to see if I can use Argon plasma. My copper layer is
> much thicker than gold.
>     Any suggestion?

Richard,

Sputter etching with Argon is non-selective, and because of the atomic mass
ratios of Cu and Au to Ar you'd preferentially etch the Cu, and get a lot
of redeposition. Besides the etch rates would be really low, like a few
Angstroms/minute in diode or soft RF etch mode.

Unless you actually use your substrate in target mode (i.e. low impedance,
several kW DC, several hundred Volts of bias, cooling) and at least Krypton
as sputter gas you can _forget_ patterning micron-thick metal films this
way. Even then, redeposition would be a major issue.

best regards,
klaus


--
Klaus Beschorner
Metron Technology, European Applications Manager
Drosselweg 6,71120 Grafenau,Germany. Tel +49-7033-45683