Analytical Study of Interfacial Layer Doping Effect on Contact Resistivity in Metal-Interfacial Layer-Ge Structure

We present a new model to demonstrate the effect of heavily doped interfacial layer (IL) insertion on contact resistivity reduction in metal-germanium (Ge) structure. It is found that the doping of IL results in lowering Schottky barrier of Ge significantly, and based on this lowering effect, a metal-IL-semiconductor model is newly proposed. From this model, the abrupt reduction of contact resistivity is observed in heavily doped condition as IL thickness is increased, and the minimum contact resistivity for 1 × 10²⁰ cm^-3 doping concentration is reduced by ×25 compared with that of undoped one. These results are promising toward enhancing the device performance of Ge MOSFET, which is for sub-22-nm CMOS technology.