Hmm.  I believe that warm hydrogen peroxide should be effective; I've
used for etching Ti over Cu preferentially.  That also is comparable
to the article published in Journal of MEMS, vol. 12, no. 6, December
2003, wherein the numbers are noted.

-Eric Woods

> Could anyone help me to solve the problem of etchnig Cr/Cu?
> The Cu is on top of the Cr.