Effect of Be segregation on NiSi/Si Schottky barrier heights

Abstract

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.

A Modified Scheme to Reduce the Specific Contact Resistivity of NiSi/Si Contacts by Means of Dopant Segregation Technique

“…A lot of methods have been reported to tune SBH of NiSi, e.g., surface passivation, [16][17][18][19][20] alloying [21][22][23] and dopant segregation (DS) technique. [24][25][26][27][28][29][30] The latter technique has been proved to be able to tune the SBH effectively and reliably. 25,26 In conventional scheme with DS technique, NiSi films were usually pre-formed at 500 • C and followed by ion implantation (I/I) into them.…”