Hi All,

I am trying to scribe GaAs wafers with back side up. The back side has streets
and gold pads. Gold pads are obtained by a lift-off process or through gold
etching, I have tried both. Due to these chemical processes the street of GaAs
is getting rough and causing scribing problems. I tried etching the wafer in
NH4OH:H2O2:H2O in 1:1:10 ratio to smoothen the streets. This is causing an
undercut and the gold pads are getting lifted off.

Can anyone suggest me a chemical process to smoothen the GaAs surface to a near
mirror finish so that scribing can be done?

Thanks

Deepa