Modeled specific contact resistivity with high doping effects: Requirements for 1 nΩ-cm2 contacts

A new compact model is given for the specific contact resistivity (ρ_C) on n⁺-Si. The significance of the model lies in the consideration of two high doping effects at the same time: (1) image force barrier lowering, (2) band-edge tailing and impurity-band barrier enhancement. The model is used for estimating the requirements on contacts with ρ_C <; 10 nΩ-cm². It is shown that 1 nΩ-cm² contacts may be achieved on n⁺-Si with doping density N_D ≤ 3 × 10²⁰ cm^-3 for intrinsic Schottky barrier height φ_B0 ≤ 0.38 eV. This estimate is more optimistic than previously predicted by models that ignored high-doping effects. The model is in excellent agreement with experimental data obtained on NiPtSi/n⁺-Si and NiSi/n⁺-Si contacts with N_D ≈ 1.5 - 2 × 10²⁰ cm^-3.