Molten indium forms a sub-oxide in air that will form a light bond to
silicate surfaces. Since the indium sitting on top of the interface is so
ductile, it is difficult to tear off the interface by pulling on the indium.

With 30 nm of evaporated material, you will not get this sort of wetting but
the adhesion to the substrate may be more than adequate for bonding
purposes. If not, you should sputter a bond layer on first (e. g., 200-300
angstroms of chromium).

-Jim Intrater