Elimination of the Parasitic Metal Resistance in Transmission Line Model for Extraction of Ultralow Specific Contact Resistivity

Abstract

A metal-resistance-aware transmission line model (MRA-TLM) is developed to eliminate the parasitic metal resistance from the extraction of specific contact resistivity $\rho _{c}$ in the metal/semiconductor contact. The proposed MRA-TLM is verified by Synopsys technology computer-aided design (TCAD) simulation, and a superior extraction accuracy as compared to the conventional TLM-based method is achieved. The proposed MRA-TLM is experimentally demonstrated in the metal/p+-Ge0.95Sn0.05 (p+-GeSn) contacts. Ultralow $\rho _{c}$ values of ${7.5} \times {10}^{-{10}}$ and ${2.1} \times {10}^{-{9}} \,\, \Omega \cdot \text {cm}^{{2}}$ are extracted by MRA-TLM for Ni/p+-GeSn and Ti/p+-GeSn contacts, respectively, which are in good agreement with ${9.5} \times {10}^{-{10}}$ and ${2.6} \times {10}^{-{9}} \,\,\Omega \cdot \text {cm}^{{2}}$ extracted numerically by the two-layer distributed-resistor-network model (TDM), qualifying the proposed MRA-TLM for the extraction of ultralow $\rho _{c}$ down to sub- $10^{-{9}}\,\,\Omega \cdot \text {cm}^{{2}}$ regime. In contrast, the $\rho _{c}$ extracted by the conventional TLM-based method is more than three times higher due to the parasitic metal resistance.