This paper reports on the electrical characteristics of thermally grown SiO2 on cubic silicon carbide (3C-SiC). The 3C-SiC (111) was grown on Si-face 6H-SiC (0001) on-axis substrates by a non-conventional Vapor-Liquid-Solid (VLS) technique. Scanning probe microscopy techniques, including Atomic Force Microscopy (AFM), Scanning Capacitance Microscopy (SCM) and tunneling AFM (TUNA) were employed to study the morphology, local capacitance and local current variations across the sample surface. This nanoscale investigation allowed monitoring the homogeneity, as well as reliability in terms of dielectric breakdown (BD), of the thermally grown SiO2. In this way it was possible to gain insights into the breakdown related to pre-existing defects (extrinsic breakdown) as well as the actual intrinsic breakdown of the dielectric.