Bonjour everyone,

I have some trouble of reproducibility to etch a thin film of permalloy (~20nm)
using dilluted aqua regia (3 HCl : 1 HNO3 : 10 H2O). I've been doing dozen of
tests using different dillutions on sample structured with photoresist AZ 5214
to measure a step with a profilemeter afterward and this ratio seems to provide
a correct etch rate for the thickness I'm working with.

If the surface not protected by the resist is visibly etched (under microscope,
the layer seems roughened or regularly perforated), no step can be measured with
the profilometer, though an evident contrast appears between the two layers.
At least I attend to etch small patterns (~1µm) on a thin film of permalloy
(~10nm), and until now I've encountered serious problems of undercut, though it
worked once by chance...
Could anyone tell me if the wet etching is a right way to proceed and then
what's the most adequate solution to use.

kind regards

Vincent Vlaminck