A Study on Carbon-Nanotube Local Oxidation Lithography Using an Atomic Force Microscope

In this paper, nanoscale anodic oxidation lithography using an atomic force microscope (AFM) is systematically studied on carbon nanotubes (CNTs). Trends between the produced feature size and the corresponding process parameters, such as applied voltage, water meniscus length, tip speed during oxidation (hold time), and humidity are observed. By methodically varying these process parameters, the appropriate working ranges have been found to create features of various sizes based on the oxidation of the CNT structure. We have obtained feature sizes down to 58 nm by setting oxidation time per pixel to 20 ms corresponding to a tip speed of 1.50 mu m/s. Optimizing the tip speed during line scans was found to be critical in maintaining the presence of the water meniscus, which was often found to break above the tip speeds of 1 mu m/s. In addition, a comparison of the results from employing this technique between CNT and graphene patterning is illustrated. Other factors affecting the reproducibility of the results are addressed in an endeavor to make the oxidization process more robust and repeatable.