Toward Single-Atomic-Layer Lithography on Highly Oriented Pyrolytic Graphite Surfaces Using AFM-Based Electrochemical Etching

Abstract

Atomic force microscopy (AFM)-based electrochemical etching of a highly oriented pyrolytic graphite (HOPG) surface is studied toward the single-atomic-layer lithography of intricate patterns. Electrochemical etching is performed in the water meniscus formed between the AFM tip apex and HOPG surface due to a capillary effect under controlled high relative humidity (~ 75%) at otherwise ambient conditions. The conditions to etch nano-holes, nano-lines, and other intricate patterns are investigated. The electrochemical reactions of HOPG etching should not generate debris due to the conversion of graphite to gaseous CO and CO2 based on etching reactions. However, debris is observed on the etched HOPG surface, and incomplete gasification of carbon occurs during the etching process, resulting in the generation of solid intermediates. Moreover, the applied potential is of critical importance for precise etching, and the precision is also significantly influenced by the AFM tip wear. This study shows that the AFM-based electrochemical etching has the potential to remove the material in a single-atomic-layer precision. This result is likely because the etching process is based on anodic dissolution, resulting in the material removal atom by atom.

Structure Fabrication on Silicon at Atomic and Close-To-Atomic Scale Using Atomic Force Microscopy: Implications for Nanopatterning and Nanodevice Fabrication

“…Apart from Si, materials such as, highly oriented pyrolytic graphite (HOPG), gold, silicon carbide and van der Waals materials such as transition metal dichalcogenides (TMD) are also potential candidates for atomic-scale manufacturing studies using AFM. As a step towards this, in our recently published article, we have shown that a single atomic layer removal over HOPG can be achieved [26].…”

Polishing Approaches at Atomic and Close-to-Atomic Scale

“…In addition, there are electrochemical modification [ 158 ], anodic oxidation [ 109 ], and ultraviolet photocatalysis modification [ 159 ] that can be considered for polishing. The search for more suitable modification approaches and finding a balance between modification and removal can focus research to improve the efficiency and precision of the chemical modification polishing processes.…”

Tooling aspects of micro electrochemical machining (ECM) technology: Design, functionality, and fabrication routes

“…Hence, by reducing the tool size, the electrochemical reaction can be limited to the sub-micro and even nanoscale (Huh et al, 2017;Malshe et al, 2010), As an example, with an ultra-short pulse coupled with an atomic force microscope (AFM) cantilever tip (Fig. 16 a and 16b), the dimension of the machined groove can be confined to be less than 100 nm (Han et al, 2022;Lee et al, 2010). The alternative way is to decrease the size of the electrolytic cell, which then acts as both the electrolytic cell and the tool.…”