Different Etching Mechanisms of Diamond by Oxygen and Hydrogen Plasma: a Reactive Molecular Dynamics Study

Abstract

Understanding the plasma etching mechanism of diamond is of great significance to promote diamond applications; however, insights into the atomic-scale etching mechanisms are hidden by the complex chemical reactions during the etching process due to the lack of an in situ characterization technique into the etching process. Herein, we conducted an etching simulation of diamond using the reactive molecular dynamics simulation method to comparatively investigate the different etching mechanisms of diamond by oxygen and hydrogen plasma with different incident energies. In the case of oxygen etching, at all tested incident energies, C−C bonds on the diamond surface are dissociated by the irradiated oxygen, and carbon atoms of diamond are etched away via the generation and desorption of gaseous carbon monoxide and carbon dioxide molecules. In the case of hydrogen etching, at low incident energies, we revealed that the carbon atoms are etched through the desorption of gaseous hydrocarbon molecules similar to the oxygen etching mechanism, while with increasing the incident energies, we interestingly observe an obvious different etching mechanism, that is, the irradiated hydrogen penetrates into the inside of diamond resulting in the formation of the hydrogenated amorphous layer which is then exfoliated from the diamond surface. Meanwhile, we revealed that the loss rate of carbon atoms in the diamond structure by oxygen is higher at low incident energies but lower at high incident energies than that by hydrogen. This study provides more insights into the etching mechanism of oxygen and hydrogen plasma and offers useful theoretical guidance for designing and controlling the etching process.

Nanoscale three-dimensional fabrication based on mechanically guided assembly

“…5 ). It is also expected that these materials can be transferred with H 2 plasma treatment without oxidation 20 .

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The Etching Mechanisms of Diamond, Graphite, and Amorphous Carbon by Hydrogen Plasma: A Reactive Molecular Dynamics Study

“…[29] Further elaboration on the ReaxFF methodology has been documented in previous scholarly inquiries. [15,17,21] In this investigation, the well-trained ReaxFF parameter [30] was utilized to investigate the hydrogen plasma etching of diamond, graphite, and amorphous carbon. The aforementioned parameter aptly characterized carbon-and silicon-based solid systems as well as the etching phenomena governed by gaseous molecular products.…”

“…This phenomenon has also been validated by previous research. [21] For the etching of graphite (0001) by hydrogen atoms, as illustrated in Figure 4b. Based on the time required to reach the non-etchable layer, it can still be concluded that higher energy hydrogen atoms result in a faster etching rate of graphite.…”

“…They found that the loss rate of carbon atoms in the diamond structure due to oxygen is higher at low incident energies but lower at high incident energies than that due to hydrogen. [21] Other studies have also shown that the ReaxFF method has the ability to model complex reactions involved in etching processes. [22][23][24][25][26][27][28] In this paper, we will use molecular dynamics simulations based on ReaxFF to investigate and compare the etching mechanisms of diamond (001), graphite (0001), and amorphous carbon films when irradiated by hydrogen plasmas.…”

“…They found that the loss rate of carbon atoms in the diamond structure due to oxygen is higher at low incident energies but lower at high incident energies than that due to hydrogen. [ 21 ] Other studies have also shown that the ReaxFF method has the ability to model complex reactions involved in etching processes. [ 22–28 ]…”