Hi,
        Generally, Chromium and Gold are the metal layers that used for
masking purposes. But care should be taken while deposition to ensure that
the deposited Metal layer is inherently free from any PinHoles and dust
particle sedimentation during the deposition process. This could result in
formation of small pits on the wafer surface. A post metallization annealing
is generally carried out to harden the deposited Cr layer before KOH
etching.
with regards,
Suchitav
[email protected]