Hi, Thank you guys for replying. Actually, when I asked 'etching', I did mean the plasma sputter off material. Because I have other components on some area of the wafer, the wet etching process can damage my components. So, I am thinking an inert Ar plasma may be better choice to remove the 100nm Au and Cr. If any of you could give me something to start with, then I may be able to work out my own parameters more quickly. Thanks again. Yingtao