Numerical Simulation Of Ar/SiH₄/H₂ RF Glow Discharge At Atmospheric Pressure

Low temperature plasma can be applied to science and technology and many fields of industries,currently,many of the low temperature plasma mostly produced by low pressure which needs large and complex vacuum system and the corresponding equipment.Plasma produced under atmospheric pressure has been a goal pursued by the people.With the deepening of the study,the application of atmospheric pressure plasma gradually bulges in each field.In order to apply atmospheric pressure plasma to industrial field,we must fully understand the mechanism of atmospheric pressure plasma discharge as well as the physical and chemical processes and master the basic parameters of plasma.Since the first report of glow discharge at atmospheric pressure in 1988,more and more people launch into the study on the atmospheric pressure discharge.In this paper,the characteristics of RF glow discharge of Ar/SiH₄/H₂ at atmospheric pressure with the structure of flat-plate electrodes are investigated by numerical simulation, giving the densities of electron,ion and radicals and the space-time evolution of current,on the other hand,considered the particle density and electron field under the influence of hydrogen dilution ratio.In the process of numerical calculation,finite difference method is employed to solve the continuity equation of particles,and Poisson equation is replaced with current conservation equation to solve electric field which simplified the program.The results of the simulation show that discharge current is composed of displacement current,electron conduction current and ion conduction current.In the different area of discharge,current has different magnitude,at and near the electrode,the displacement current provides the current, and displacement current is much larger than the electronic conduction current and ion conduction current.When the electrode is the instantaneous anode,electronic conduction current is larger than ion conduction current and when the electrode is the instantaneous cathode,electronic conduction current is smaller than ion conduction current.Ion conduction current has the maximum at and near the electrode,nevertheless it is one order of magnitude smaller than displacement current.In the plasma,most current is electron current.During the discharge of electronegative gas participation in reaction,the mainly negative particle is SiH₃^-, SiH₃ is the most important radical produced from the chemical reactions between the electron and gas molecules,it takes the most proportion,it is the precursor of the deposition of thin film, it is helpful to improve the thin film deposition rate by increasing the number of SiH₃,at the same time,discussed the variation of electron,ion,and radical densitys with the hydrogen dilution ratio.The results shows that the particle densities and electron field decrease with it increase.