Numerical Simulation Of Reaction Characteristics Of Diamond Prepared By Thermally Excited Chemical Vapor Deposition

Diamond is a material with extremely high hardness and thermal conductivity among the materials currently used,and it has a wide range of applications in the fields of microelectronic materials,optical materials,and hard coatings.However,natural diamonds require harsh high temperature and high-pressure environments,so natural diamonds are stored in a small amount in nature.The diamond synthesized by the high temperature and high-pressure method cannot be produced on a large scale due to the limitation of the mold,and the synthesized diamond also contains a small amount of metal catalyst,and the performance is low.Chemical vapor deposition technology has the advantages of high deposition quality and a stable deposition process.It is currently the best method for synthesizing diamond films.However,the specific mechanism of diamond deposition is still unclear.In this paper,hot-wire chemical vapor deposition and combustion flame chemical vapor deposition were selected for numerical simulation,which laid the foundation for the study of the specific mechanism of diamond deposition.In this paper,firstly,numerical simulation is carried out for hot-wire chemical vapor deposition,and the influence of different hot-wire temperatures and different deposition chamber pressure on the concentration distribution of main chemical groups in the deposition chamber is studied.The concentrations of H atom groups and C₂H₂ groups gradually increase with the increase of the temperature of the hot filament.When the temperature of the hot filament is lower than 2600K,the concentration of the CH₃ group gradually increases with the increase of the temperature of the hot filament.The change is not obvious at 2600K,and the decomposition rate of the CH₄ group increases as the temperature of the hot wire increases,resulting in a gradual decrease in the concentration.The concentration of the H atom group,CH₃ group,and C₂H₂ group gradually decreased with the increase of deposition pressure,and the concentration of the CH₄ group gradually increased with the increase of deposition pressure.The flow field in the deposition chamber is analyzed.When the deposition pressure is greater than 3000 Pa,a recirculation zone will be formed in the deposition chamber.With the increase of the deposition pressure,the recirculation zone gradually increases.The deposition conditions were discussed.Increasing the temperature of the hot filament and reducing the deposition pressure is beneficial to increase the rate and quality of diamond growth.In this paper,the numerical simulation of the combustion flame chemical vapor deposition is carried out to study the variation of the temperature field of the one-step reaction of acetylene with the volume ratio of acetylene and oxygen.After introducing the detailed reaction mechanism,different oxygen-to-acetylene ratios and different amounts of hydrogen are added to the active radicals in the acetylene flame.The influence of the regiment.When the inlet flow rate is constant,the maximum temperature of flame combustion gradually increases with the increase of the oxygen-acetylene ratio.The high concentration area of H atom groups is concentrated on the ventral surface of the substrate,and the concentration of H atom groups gradually decreases with the increase of the R-value.The high concentration area of HCCO groups is mainly concentrated in the middle of the flame,and the peak concentration of HCCO groups gradually decreases with the increase of the R-value.The high concentration area of OH groups is concentrated on the central axis of the substrate,and the concentration on both sides is 0,and the peak value of OH groups gradually decreases with the increase of the R-value.Under the condition that the flow rate of oxygen and acetylene remains unchanged,adding hydrogen can increase the concentration of H atom groups,HCCO groups,and OH groups in the flame,which is conducive to the nucleation and growth of diamond.