Fabrication of metal-nitride/Si contacts with low electron barrier height

We have successfully fabricated a TiN/Si contact with low electron barrier height (Φ_BN) in our previous study. In this study, we fabricated Ti, Zr, Hf, TiN, ZrN, and HfN/Si contacts using rf sputtering method and evaluated their electrical characteristics. The results of metal/Si contacts well-consisted with reported results. On the other hand, the Φ_BNs of metal nitride/Si contacts were remarkably low compared with those of the metal/Si contacts, which deviate largely from the empirical relation of Φ_BN versus metal work function. This is considered to be attributable to an interlayer with nitrogen atoms between the metal nitride and Si. The back-gate MOSFETs with TiN, ZrN, and HfN as source/drain were fabricated, showing the normal device operation. From the device characteristics, the off-state current and parasitic resistance were associated with Φ_BN of metal nitride. We believe that these fundamental data are useful for applying metal nitride to metal/Si contacts.