Effect of Be segregation on NiSi/Si Schottky barrier heights

The effect of Be segregation on the Schottky barrier heights (SBH) of NiSi/Si is studied. Many elements have been shown to modulate the SBH of NiSi. However, group II elements have, to our knowledge, not been investigated before. Be is a double acceptor in Si, making it interesting for SBH modulation towards the valence band. The results show that Be implantation did not change the silicidation process. The SBH modulation was found to be strongly dependent on the silicidation temperature, with a minimum barrier to the valence band Φ
_bp
=0.28±0.02 eV, for diodes formed at 600 °C. SIMS analysis show the Be dose left at the interface is very low. With such a low dose, modulation cannot be caused by an interface dipole. However, the results can be explained assuming a thin (~4-5 nm) layer of activated Be close to the interface.