A new mechanism of leakage current in ultra-shallow junctions with TiSi2 contacts

For shallow n⁺/p and p⁺/n junctions with TiSi₂ contacts, the leakage current quite frequently increases after silicidation. When the Ti layer for silicidation is thick, the leakage current of shallow p⁺/n junctions increases much more strongly than shallow n⁺/p junctions after silicidation. This is usually explained by Si consumption due to silicidation. When the Ti layer for silicidation is thin, the leakage current of shallow n⁺/p junctions increases more strongly than shallow p⁺/n junctions after silicidation. In this paper, a new mechanism of Ti⁺ drift due to the built-in electric field is proposed to explain the larger leakage current of shallow n⁺/p junctions than that of shallow p⁺/n junctions after silicidation. A numerical simulation with the pc-1d software package was performed to calculate the electric field distribution for shallow junctions under various conditions