  We report observations of unusual normal-state electronic conduction
properties and superconducting characteristics of high-quality CoSi$_2$/Si
films grown on silicon Si(100) and Si(111) substrates. A good understanding of
these features shall help to address the underlying physics of the
unconventional pairing symmetry recently observed in transparent
CoSi$_2$/TiSi$_2$ heterojunctions [S. P. Chiu \textit{et al.}, Sci. Adv.
\textbf{7}, eabg6569 (2021); Nanoscale \textbf{15}, 9179 (2023)], where
CoSi$_2$/Si is a superconductor with a superconducting transition temperature
$T_c \simeq$ (1.1--1.5) K, dependent on its dimensions, and TiSi$_2$ is a
normal metal. In CoSi$_2$/Si films, we find a pronounced positive
magnetoresistance caused by the weak-antilocalization effect, indicating a
strong Rashba spin-orbit coupling (SOC). This SOC generates two-component
superconductivity in CoSi$_2$/TiSi$_2$ heterojunctions. The CoSi$_2$/Si films
are stable under ambient conditions and have ultralow 1/$f$ noise. Moreover,
they can be patterned via the standard lithography techniques, which might be
of considerable practical value for future scalable superconducting and quantum
device fabrication.
