Low-Contact-Resistivity Nickel Germanide Contacts on n+Ge with Phosphorus/Antimony Co-Doping and Schottky Barrier Height Lowering

Recently high mobility channel materials are attracting much interest for future CMOS scaling. Among the choices, Ge is particularly promising for both n and p-MOSFET with its compatibility with silicon processing and its high carrier mobilities. In summary a low ρc of 5.5x10-7 Ω.cm2 is achieved in NiGe contacts on n+ Ge co-doped with P and Sb. The SBH and ρc reduction by dopant segregation at NiGe/Ge interface, with a SBH ~0.1 eV lower than Al/Ti contacts are explained. The combination of P/Sb co-doping technique and germanide process provides a promising method to achieve low ρc as well as low R_sh on n+ Ge.