Role of electric field distribution in local anodic oxidation

Local electric-field-induced anodic oxidation is one of the earliest and most extensively studied techniques in bias-assisted AFM nanolithography. Except the water bridge created between the tip and the sample surface, local anodic oxidation (LAO) process strongly depends on the tip-sample voltage and especially on the electric field distribution under the tip apex center. Once electric field is formed, its distribution and intensity can be modified by changing the tip-sample voltage and separation. The electric field provides the oxidation kinetics of nanoscale electrochemical reaction and controls the spacial resolution of the fabricated structures. In this paper, the s-wave tip quantum model, the influence of the bias voltage and the electric field strength on oxide structures and the theory of electric-field-induced LAO have been analyzed. In addition, dot-array nanogratings, one-dimensional nanogratings and two-dimensional nanogratings are fabricated by using electric-field-induced LAO process with AFM in the ambient atmosphere.