Effect of Metal Nitride on Contact Resistivity of Metal-Interlayer-Ge Source/Drain in Sub-10-nm n-Type Ge FinFET

Abstract

A metal nitride-interlayer-semiconductor source/drain (MN-I-S S/D) model is newly proposed to investigate the effect of tantalum nitride (TaN) on the specific contact resistivity (rho(c)) of an MN-I-S S/D with an undoped interlayer (undoped-IL) or a heavily doped IL (n(+)-IL) in sub-10-nm n-type Ge FinFETs. In this model, the workfunction variation of TaN was considered following the Rayleigh distribution. Compared with MN-I-S structures with an undoped-IL, structures with an n(+)-IL generate much lower rho(c) values (i.e., similar to 2 x 10(-9) Omega . cm(2)) and are less prone to variation. In addition, the impact of rho(c) variation on device performance is investigated using 3-D technology computer aided design simulation for undoped or heavily doped ILs in MN-I-S S/D structures. MN-I-S S/Ds with an n(+)-IL can achieve much lower current variation and a higher ON-state drive current.