Feasibility of the electrical characterization of single SiO2 breakdown spots using C-AFM

Due to the progressive scaling down of MOS devices, new methods are require d to study the failure mechanisms of the gate oxide in a nanometer range. I n this work, an atomic force microscope equipped with a conductive tip and a sensitive preamplifier has been used to study the electrical properties a nd degradation dynamics of single breakdown spots of 3-6 nm SiO2 films on a nanometer scale. With this purpose, voltage ramps over areas of 30-50 nm(2 ) (of the order of the breakdown spot area) have been repeatedly applied to induce the degradation of the SiO2 films. Similar results to those observe d with conventional tests (such as the switching between two states of well -defined conductivity) have been measured with this technique. As a conclus ion, our results point out the conductive atomic force microscope as a tool for the analysis of the electrical properties and degradation of single br eakdown spots. (C) 2001 Elsevier Science B.V. All rights reserved.