Numerical Simulation Of Plasma Characteristics And Reaction Process In Microwave Chemical Vapor Deposition Chamber

Microwave plasma chemical vapor deposition technology(Chemical Vapor Deposition)is a new technology developed for the preparation of carbon materials in recent decades.Compared with other CVD technologies,microwave plasma CVD technology has the advantages of high deposition quality,large deposition area,and stable deposition process.At this stage,microwave plasma CVD technology is the best method for synthesizing high-quality carbon materials,but its bottleneck lies in the low deposition rate.The deposition rate of this equipment is generally in the range of 0.1～34 ?m/ h.And now people’s understanding of the deposition mechanism of this technology is still being explored.This paper studies the influence of process parameters on the characteristics of microwave plasma and the chemical reaction kinetics process in the deposition chamber,which lays some foundation for solving the bottleneck of microwave CVD technology.First of all,this paper builds a coupled multiphysics model for microwave plasma,involving electric field,plasma and temperature field.The characteristics of plasma generated by electromagnetic field excitation are characterized by: electric field strength,electron density,gas temperature,and electron temperature.Through research,it is found that different characteristic quantities have different sensitivity to process parameters.Electric field strength and electron density are greatly affected by microwave power,while gas temperature and electron temperature are greatly affected by deposition pressure.And the volume of the plasma ball increases with the increase of microwave power,and shrinks with the increase of the deposition pressure,so in order to increase the power density without changing the size of the plasma ball,two parameters need to be adjusted synergy.Then this paper establishes a coupling model involving chemical reaction,flow heat transfer,and material transport process for the chemical reaction kinetic process in the deposition chamber.The reaction mechanism studied involved 13 neutral substances and 43 elementary reactions,and studied the spatial distribution of the active substances generated in the deposition chamber,the conversion between the single carbon material and the double carbon material and the way of gas flow in the chamber.The study found that,according to the positive correlation principle,H group,CH3 group and C2H2 molecule are the substances that are most likely to benefit the carbon material deposition process and promote it.In the study of the conversion process between the active materials in the deposition chamber,it was found that CH3 and C2H2 were the highest proportions of single-carbon and double-carbon materials,respectively.When studying the flow pattern in the deposition chamber,it was found that when the gas temperature is relatively high,it will be conducive to the reflux phenomenon in the deposition chamber.According to the review,the study of the plasma characteristics and chemical reaction kinetics in the microwave deposition chamber is helpful for the understanding of the deposition mechanism,and also laid the foundation for further research on the microscopic growth process of carbon materials.