Scanning capacitance microscopy (SCM), combined with atomic force microscopy (AFM), was employed to investigate the dielectric breakdown phenomena in thin SiO2 films. The localized breakdown spots can be clearly imaged by the SCM technique. The spots exhibit signals with low differential capacitance (dC/dV) due to high conductivity. The diameters of these breakdown spots were approximately from 6 to 13.5 nm. Moreover, according to the corresponding AFM images, their surface morphology showed little change after the occurrence of oxide breakdown. (c) 2005 The Electrochemical Society. All rights reserved.