Greetings,

The top layer of Cr is no problem it will be etched away with the gold layer.
 A very common gold etch is the Iodine etch made from 400 gm of KI plus 100
gm of Iodine add the ingredients in the order listed to say 300 ml of DI
water dissolve the KI completely before adding Iodine crystals then dilute to
400 ml for the final solution.  This solution etch gold to fast for the thin
gold you are using so dilute a portion 4:1 with DI water to make an etchant
of 500 to 1000 A/min.  The etching process is done by dipping in the solution
for a few seconds then quickly rinsing in running DI. Inspect and then
re-etch again. Repeat this process a few times to find the end point as it is
impossible to see this end point in the dark Iodine sol.

As for the bottom Cr layer can be etched with the following Cr etch. 9 parts
saturated solution of Cerric Sulfate and one part of Nitric acid (70%). All
parts are by volume.

Caution: neither of these etchants can be poured down the drain and must be
disposed of in a safe to the environment manner. This could be a big problem.

My personal favorite method is to Sputter Etch the multi metal sandwich. The
etched pattern will exactly match the resist pattern and no waste disposal
problems to deal with.  The process requires a suit sputtering system,
however.

Regards,

Campman