Plasma, also known as "plasma" or "hypergas", is an ionized gaseous substance composed of atoms whose electrons have been partially stripped and the positive and negative electrons generated by ionization of atoms. It is the fourth state of matter besides solid, liquid, and gas.

Principles of Plasma Etching Technology

Plasma etching is an important means of removing surface substances and is an indispensable process in modern semiconductor processing technology. The plasma etching process involves both physical and chemical mechanisms. Its principle is to discharge the etching gas, use the free functional groups in the plasma to bombard or sputter the surface molecules of the etched material, or use chemically active functional groups to react with the substances in the etched material to form volatile substances, in order to achieve the purpose of etching. Plasma etching method has the advantages of fast etching rate, good etching uniformity, and less etching residue.

Graphene, as an electronic material with excellent electrical properties, has a carrier density that can be controlled by an applied voltage, and its carrier mobility is two orders of magnitude higher than that of silicon materials. The development of graphene nanoelectronic devices is very rapid. Graphene samples prepared by mechanical exfoliation or chemical vapor deposition have inconsistent layers and shapes, and need to be patterned.

There are various methods for modifying and modifying graphene, including oxidation-reduction, functionalization of chemical bonds, doping of metal ions, and plasma etching. Among them, plasma etching is very effective and is also a common modification method gradually adopted by many scholars.

Principle of Oxygen Plasma Etching Graphene

In the process of oxygen plasma bombardment of graphene, the basic reaction is the oxidation reaction between oxygen plasma and the surface C atoms in graphene. Whether CO2 or CO is generated, it belongs to a vacuum state in the reaction chamber of the plasma device. Therefore, the reaction gas will be pumped out of the vacuum reaction chamber, and the graphene with lost C atoms will undergo many structural and performance changes. However, in the process of oxygen plasma etching graphene, there is not only a basic reaction between C and oxygen plasma, but oxygen atoms may also replace C atoms and penetrate the graphene layer.

Oxygen plasma etching has become the main method for visualizing graphene. It uses oxygen plasma to bombard graphene, causing the carbon carbon bonds in graphene to break, and carbon atoms react with oxygen atoms to generate carbon monoxide (CO) and carbon dioxide (CO2) gases, achieving the etching of graphene. Oxygen plasma etching of graphene will expand the defects in the upper layer of graphene, separate the boundaries, reduce roughness, and to some extent introduce new defects to the top layer of graphene. These structural changes will have a certain impact on other properties of graphene.