The 3C-SiC silicon carbide is a promising substrate material for MOS transistors. Parameters of MOS transistors are strongly dependent on the processing of the semiconductor-dielectric system. We study and compare the crucial features of the SiC(3C)-SiO2 systems with thermally grown and PECVD deposited SiO2 layers. For both types of systems, using the Al-SiO2-SiC(3C) capacitors as test structures, we determine and compare the following properties: The leakage currents and breakdown voltages of SiO2 layers, densities and distributions in energy of interface traps, band diagrams of the SiC(3C)-SiO2 systems, as well as structural properties and mechanical stresses in both types of SiO2 layers. Characterization of the above mentioned features is done using electrical, photoelectric and optical methods, including micro-Raman spectroscopy. The characterization results lead us to the conclusion, that PECVD deposition of SiO2 followed by wet oxygen annealing is more advantageous for MOSFET fabrication than the thermal growth of the SiO 2 layer.