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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">it</sub> ) and the density of metal-induced gap states (D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MIGS</sub> ) at the semiconductor surface. Previous studies on MIS contact modeling have quantified only the impact of D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MIGS</sub> 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 (ρ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> ). The physical validity of the proposed model is demonstrated by comparing its calculated ρ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> with those obtained in prior experimental studies employing a GaAs substrate (Ti/ZnO/n-GaAs and Ti/TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /n-GaAs). The ρ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> values for the MIS contacts are also evaluated with various D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">it</sub> 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.