Surface microroughness and its effects on dielectric breakdown characteristics have been investigated for silicon wafers treated in SC1-based solutions. Surface microroughness was quantified using atomic force microscopy (AFM) and phase shift interferometry (PSI). In contrast to previous reports that SC1 treatment caused undulation of the surface, our observation showed a nominal amount of deterioration. Even prolonged dipping in a solution with high etching rate did not roughen the surface, and the dielectric breakdown characteristics were not affected.