Enhanced probe nano-oxidation by charge pump effect in swept tip voltage cycles

Abstract

A probe-based nano-oxidation method for enhanced vertical oxide growth on silicon is presented. The technique involves cycling the tip biases between positive and negative polarities to produce high-aspect-ratio nano-oxides. Enhanced oxidation was observed to take place in the positive tip bias region as opposed to the negative tip voltage required for anodic oxidation. A model based on interface space charge accumulation and neutralization, O H- reactant mobilization, and diffusion is proposed to account for the oxidation enhancement observed under positive tip voltages. The proposed model is analogous to the transient charge pump effect which is at work when the polarity of a capacitor is switched. The results reveal the dynamical behavior of nano-oxidation under nonstatic fields which can be harnessed for fabricating oxide nanostructures with improved aspect ratios. © 2007 American Institute of Physics.