Hi,
I have observed in my experiments that dilute aqua regia (3 parts HCl : 1 part
HNO3 : 2 parts H2O) dissolves evaporated Gold at a rate of ~3nm/s, but etches
Titanium very slowly or not at all.  Therefore Titanium can be used as an etch
mask when etching Gold with this chemistry.  Also, Titanium can be dissolved
with 1:2 or 1:3 NH4OH:H2O2 at a rate of 2.5nm/s, but does this chemistry does
not etch Gold.

So in my application, I am considering etching Titanium with the HN4OH:H2O2
chemistry while masking certain parts of the Titanium with AZ5214E resist.  Does
H2O2 attack AZ5214E resist?

Also, I intend to use Titanium as an etch mask when etching Gold with Dilute
Aqua Regia.  The Gold is evaporated on patterns of crosslinked and uncrosslinked
SU-8 2050.  Does the HCl and HNO3 chemicals in Aqua Regia attack uncrosslinked
SU-8?

Can someone help to answer my queries?  Thanks a bunch!

Jeffrey