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-cm
²
. It is shown that 1 nΩ-cm
²
contacts may be achieved on n
⁺
-Si with doping density N
D
≤ 3 × 10
²⁰
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 − × 10
²⁰
cm
⁻³
.