I have tried chromium as a mask directly over silicon with no luck.
However, if there is an oxide layer underneath, it works great.

>
> It can be the mask. I use 500 A Cr and 2500 A Au. 30% KOH 60 degree C. At
> least 17 hour, no observable attack to the metal system.
>
> Zhijian ZHOU
> HKUST
>