The mechanism of the sequential stages of the heterogeneous chemical reaction between gaseous carbon monoxide and the surface of monocrystalline silicon is investigated. As a result of this reaction, the silicon surface is transformed into an epitaxial silicon carbide surface. A significant time-dependent change in the microstructure and properties of the forming SiC layers has been observed. The microstructure and properties of the SiC/Si layers were analyzed using reflection high-energy electron diffraction (RHEED) and spectroscopic ellipsometry (SE), while the evolution of the SiC–Si interfacial structure was studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It has been established that during the first five minutes of synthesis the elastic strain transitions from compressive to tensile. It was observed that the “precarbide” layer consists of twinned ordered layers located parallel to the interface in the (111) plane, with a period of 0.252 nm and a triple periodicity, i.e., with a spacing of 0.756 nm.