Dear all,

I faced the problem when I tried to use a KI/I2 mixture to etch gold. I
am going to pattern the Cr and Au layers on the silicon substrate, and I
used thermal evaporator to deposit the Cr and then sputter to deposit
the gold. After depositing the gold layer by using sputter, I used a
KI/I2 mixture to etch the gold layer. After etching for about 10 mins, I
saw the gold was completely etched and there should be a shiny Cr layer
under the gold layer after the wet etching. However, there is a cloudy
thin film in light brown color appeared at the bottom of the gold layer
and that layer cannot be etched in the gold etchant. I would like to
know whether you have seen this problem before, and do you have any
suggestion of the reason to cause this problem and what the layer is? Is
that layer caused by some compound generated after the gold etching?
Thank you very much!

Best Regards,
Carmen