Chemical etching study of probe-grown ultrathin nano-oxides by atomic force microscopy

Abstract

We report the study of the etching characteristics of atomic force microscopy (AFM) probe-grown ultrathin oxides (AFM oxides, up to 5nm thick). In our method, an AFM localized depth analysis technique was employed to monitor the atomic layer-by-layer etching of AFM oxides. Insights into the growth mode and etching mechanism of AFM oxides were acquired on the basis of the etching results: it was found that AFM oxide growth is related to Si out-diffusion. For the formation of ultrathin oxides in ambient conditions, it is evident that oxidation-enhanced Si diffusion facilitates the layer-by-layer oxide growth in AFM anodic oxidation. The etching rate of ultrathin AFM oxides is dependent on the SiOH silanol reactive sites. Thermal annealing could reduce the content of silanol groups and enhance the chemical stability of AFM oxides against etching.