Multiring Circular Transmission Line Model for Ultralow Contact Resistivity Extraction

Accurate determination of contact resistivities (
${\rho_{c}}$
) below
$1 \times 10^{-8}\Omega \cdot \text {cm}^{2}$
is challenging. Among the frequently applied transmission line models (TLMs), circular TLM (CTLM) has a simple process flow, while refined TLM (RTLM) has a high
$\rho _{c}$
accuracy at the expense of a more complex fabrication. In this letter, we will present a novel model—multiring CTLM (MR-CTLM) , which combines the advantages of a simple process and a high
$\rho _{c}$
extraction resolution. We fabricated ultralow-
$\rho _{c}$
Ti/n-Si contacts and demonstrated the capability of MR-CTLM to extract the
$\rho _{c}$
as low as
$6.2 \times 10^{-9}~\Omega \cdot {\rm cm}^{2}$
with high precision.