Hi
i am am trying to etch down NI layer with thickness of 100nm on nGaAs substrate. I have read reference articles mainly the handbook of metal enchants and tried using following solutions:
H2SO4:H2O ..... different ratios from 3:1 to 4:3 to 1:50. However the Ni layer did not etch but the substrate started to be etched which is not desired.
HNO3:H2O 3:7 .... not etching Ni
HNO3:HCL .... etching both nGaAs and Ni
Afte observing that the Ni is not being etched, I believe there maybe NiO on top of Ni that needs to be etched away. However to remove NiO, there is need for HNO3 which is not very appropriate for using with nGaAs. Any recommendations for etching the Ni layer?
Thanks
Normally GaAs can be cleaned by diluted Piranha Solution (H2SO4+H2O2) Your treatments may be too low pH, resulting in Ni passivation.
http://engineering.tufts.edu/microfab/documents/SOP_GaAs-WaferPrep.pdf
Thanks...however my main goal is to etch down the Ni layer and dont want to etch the substrate
Thanks. Anyone knows if any of these etchants is isotopic? Thanks!
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