The PIC/MCC Simulation Of Plasma Characteristic For A Rf Micro-hollow Cathode Discharge In Nitrogen

A radio-frequency hollow cathode discharge in nitrogen and its mixed gas has been widely used in industrial production,especially in the semiconductor industry.For example,A discharge in nitrogen may be used for a surface processing of a variety of metals and alloys,N₂-Ar discharge is more often used by magnetron sputtering to cultivate a nitride film.The plasma nitride is an economical way to improve the hardness,resistance to corrosion,abrasion resistance and surface quality of stainless steel.These excellent characteristics of the nitride are the important factors of being simulating and used in industrial production for a radio-frequency hollow cathode discharge in N₂.The hollow cathode size is getting smaller and smaller,the discharge pressure can reach high pressure,even atmospheric pressure.But the theory about micro-hollow cathode,especially high frequency and very high frequency hollow cathode discharge,is unclear at present.In this paper,comparing the radio-frequency micro-hollow cathode discharge with the conventional radio-frequency hollow cathode discharge,through changing the cathode size of the hollow cathode tube and the amplitude of the radio-frequency voltage,the cause of the generation of the micro-hollow cathode effect is studied.The results show that:micro-hollow plasma density and ion current density is much larger about one order of magnitude than the conventional hollow discharge,it illustrates the micro-hollow discharge has advantages of a large discharge current and a high plasma density;When the pressure is5Torr:the voltage amplitude is 300V,the cathode diameters are 160-800?m or the voltage amplitudes are 200V-800V,the cathode diameter is 400?m,the average thickness of the sheath has covered the diameter of the hollow cathode tube,he cause of the generation of the micro-hollow cathode effect is the overlying of sheath.In addition,in the industrial plasma process the discharge parameters have a direct impact on the plasma processing results.It has been known that the gas flow rate is an important factor of controlling plasma processing.It has a significant impact in the application to the plasma,such as etching and deposition.The included gas flow rate can not only increase the etch rate and the anisotropic etching,but also increase the deposition rate.In this paper,a two-dimensional model included gas flow rate for a radio-frequency hollow cathode discharge in N₂ were developed,the discharge process is simulated and analysed.Simulated results reveal that the energy of the electrons and ions have increased with gas flow rate included,,the mean energy of ions increases with gas flow rate;two kinds of nitrogen ion energy nearby the ground electrode increases with gas flow rate.With the gas flow rate increasing,the maximum of ion current density moves toward the ground electrode,the axial ions?N₂⁺,N⁺?current density toward the ground electrode?substrate?increases.Especially,increasing the current density nearby the ground electrode,has an important significance for the application of the plasma jet technique.The radial electric field within the hollow cathode tube mainly formed from?to 2?at a radio-frequency period,the radial electric field between the electrode gap mainly formed from 0 to?a radio-frequency period.Ion mean energy in the plasma region for the radio-frequency hollow cathode discharge is not zero.