I am trying to pattern a thick silver layer on GaAs. The thickness could
be 5000A to 1um . The pattern I try to make is a 30X20um rectanglular
openning. I once tried the silver etchant from Transene. It gave me huge
undercut and ugly etch front. Anyone has the similar problem before? I
deposit silver in CHA E-beam deposition system at about 3~5A/sec.
   Is it OK to lift off this pattern in suck a thick layer? As I know, it is
normally more difficult to lift off a small openning than a mesa or ridge.
   Anther question is, I am using AZ5214, and AZ4330 now. will the image
reversal give these PR a better profile for lift off? Will the Chlorobenzene
process or toluene work to them too?

  Thanks a lot for your help
   Qingwei

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Mo, Qingwei                                              *
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