Universal Metal-Interlayer-Semiconductor Contact Modeling Considering Interface-State Effect on Contact Resistivity Degradation

Abstract

We present a universal metal-interlayer-semiconductor (MIS) contact model to demonstrate the effect of Fermi-level unpinning, considering both the extrinsic interface-state density (D-it) and the density of metalinduced gap states (D-MIGs) at the semiconductor surface. Previous studies on MIS contact modeling have quantified only the impact of D-MIGS on Fermi-level pinning. However, the extrinsic interface states such as interface traps and local vacancies significantly affect the contact resistivity degradation in MIS contacts. Moreover, field emission (FE) and thermionic FE (TFE) current density models in MIS contact are described in detail, for the extraction of the specific contact resistivity (rho(c)). The physical validity of the proposed model is demonstrated by comparing its calculated rho(c) with those obtained in prior experimental studies employing a GaAs substrate (Ti/ZnO/n-GaAs and Ti/TiO2/n-GaAs). The rho(c) values for the MIS contacts are also evaluated with various D-it levels and the interlayers. This model is promising for the development of a comprehensive next-generation MIS contact for the sub-10-nm complementary metal-oxide-semiconductor technology.