> We use liftoff process for our chip patterning. The metallization metal is
> either gold or copper. We use same lithography process for both gold
> patterning and copper patterning. However, I notice that copper always shows
> a very clean gap after liftoff while gold always have residue on the edge of
> the gap. Can somebody explain why? Your help is very appreciated!

You are talking about metal residue, I presume. Gold is notorious for it's
low sticking coefficient, esp. on SiO2 and at elevated temperatures.
Even at 200C there is noticable surface diffusion of the deposited gold.
Copper is much less mobile after deposition.

hope this helps
klaus
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