Formation and Thermal Stability of Nickel Germanide on Germanium Substrate

The formation and thermal stability of nickel germanide on germanium substrate were examined by both electrical and physical characterization methods. Low resistivity (14 µΩ cm) mono-nickel–germanide was formed at a low temperature of 400°C on Ge substrate. The sheet resistance of nickel germanide changed with the germanide formation temperatures and had a similar characteristic as nickel silicide. However, the thermal stability study shows that NiGe formed on Ge substrate has a poorer thermal stability than NiSi on Si substrate, which is due to the lower activation energy of agglomeration in NiGe (2.2±0.2 eV) compared to NiSi.