Thin SiO 2 layers were thermally grown onto cubic silicon carbide(3 C-SiC) heteroepitaxial layers of different surface roughness and with different types of near-surface epitaxial defects. Localized dielectric breakdown(BD) was studied by electrically stressing the system using Conductive Atomic Force Microscopy(C-AFM), which constitutes a means to directly and simultaneously observe localized dielectric failure as a function of stress time and surface morphology with nanoscale lateral resolution. The BD kinetics was evaluated by fitting the experimental failure ratios as a function of stress time to the failure probability described by Weibull statistics, in turn allowing to distinguish between defect-induced(extrinsic) and intrinsic dielectric BD events. The results give useful information about how morphological features at the 3 C-SiC surface influence the BD generation in thermally grown oxides on this polytype.