Hello, Sardar Bilal,

The best way of the patterning for Cu/Ni/Ag is lift-off, of course. But if
you have to do the etching, I recommend a extremely diluent H2SO4 and H2O2.
I have tried 0.05% H2SO4 with drops of H2O2. It etches the Cu layer quickly
(about 2min for 100nm) without obvious damage for the nickel layer.

Good luck!

2008/5/29, Sardar Bilal :
>
> Hello folks !
>
> I have a question related to metal etching. I want to etch my Cu seed layer
> (100 nm by sputtering). Its a bit tricky since I also have about 100 nm of
> Ni and 100 nm of Ag on my wafer which I want to keep. I have tried 10%
> nitric acid at room temperature, but it etches Cu and Ni at almost the same
> rate, though silver is not etched significantly. I have also tested 10% HCl
> and i observed the loss of adhesion of some Ni structures (strange!) and Cu
> was not etched significantly. When the sample was taken out of HCl, it
> oxidized and Cu color changed to purple shades. I would appreciate if
> someone can recommend some wet etchants that can selectively etch Cu and
> have low etch rate for Ni and Ag.
>

--
Best regards,
Yours sincerely
Fei Wang
______________
State Key Lab of Transducer Technology,
Shanghai Institute of Microsystem and Information Technology,
Chinese Academy of Sciences
865 Changning Road, Shanghai 200050, China
Email：wangfeiustc@gmail.com
Tel:0086-21-62511070 ext.5468