A Ladder Transmission Line Model for the Extraction of Ultralow Specific Contact Resistivity—Part II: Experimental Verification

Abstract

In the first part of this two-part article, a ladder transmission line model (LTLM), featuring elimination of parasitic metal resistances and high accuracy for extracting specific contact resistivity $\rho _{\text {c}}$ , is developed and verified by simulation. In Part II, the LTLM is applied experimentally to Ni contacts formed on the heavily Ga-doped Ge0.95Sn0.05 film. Two types of Ni/p+-Ge0.95Sn0.05 LTLM structures, single-cell and multicell LTLMs, are fabricated. Ultralow $\rho _{\text {c}}$ values of ${8.6} \pm {2} \times {10}^{-{10}}\,\,\Omega {-}\text {cm}^{{2}}$ and ${1.1} \pm {0.3} \times {10}^{-{9}}\,\,\Omega {-}\text {cm}^{{2}}$ are extracted from the single-cell and multicell LTLMs, respectively. The good agreement of the extracted $\rho _{\text {c}}$ from the single-cell and multicell structures validates the $\rho _{\text {c}}$ extraction by the LTLM. $\rho _{\text {c}}$ is also extracted by using refined transmission line model (RTLM). In contrast, the extracted $\rho _{\text {c}}$ by the RTLM is more than two times larger due to the ignored parasitic metal resistance. The proposed LTLM is a useful tool for an accurate assessment of $\rho _{\text {c}}$ in advanced contact technology.