Study On Capacitively Coupled Argon Plasma At Different Driving Frequencies

As the technology of generating plasma by gas discharge becomes more and more mature,more and more plasmas are used in our life.For example,in the environment,plasma can be used for tail gas treatment.In medical treatment,it can be used for sterilization and disinfection.In terms of light source,plasma lamp and plasma display can be made.In many industrial fields,it is used in the manufacture of microelectronic equipment,thin film preparation and plasma waste treatment.Capacitively coupled plasma has a wide range of applications in integrated circuits,photovoltaic cells,flat panel display and other manufacturing processes due to its ability to produce high homogeneity plasma in a large area.The great application prospect makes people more interested in the characteristics of plasma.In recent years,many plasma generating devices with different functions have been designed at home and abroad.In the spectrum research and measurement,the spectral line intensity and the type of discharge particles,as well as the electron temperature and electron density have been analyzed.In addition,some key parameters such as breakdown voltage and electrode spacing have been experimentally studied by means of electrical means.Therefore,in this paper,three different diagnostic methods,including spectral method,electrical law and particle simulation,will be used to study the RF capacitive coupled plasma.First,using Boltzmann curve slope method to calculate the electron excitation temperature of plasma,and use continuous spectrum absolute intensity method to calculate the electron density.The excitation temperature is approximately regarded as the electronic temperature,and the variation of electronic temperature with power and pressure at different frequencies is analyzed and discussed.In addition,the changing law of electron density is emphatically analyzed.Secondly,collect the current and voltage under certain discharge conditions,and explain the change of density and temperature according to the change rule of current and voltage.Finally,The one-dimensional PIC/MCC electrostatic model is used to simulate the spatial distribution of electron temperature and electron density,the values of the center point of the polar plate are selected and compared with the calculated values of the experimental spectra.In addition,the simulation can obtain other physical quantities that can't be obtained in the experiment.The results of the experiment are analyzed from various angles,providing a reference for the study of plasma characteristics.It is shown that electron density increases with the increase of driving power,while electron temperature decreases under different driving frequencies,The current and voltage of 13.56 MHz and 100 MHz discharge both show an upward trend with the power,and the higher the frequency,the lower the voltage and the higher the current.At the same time,It is found in the simulation that the potential in the plasma region increases with the increase of power.In the process of changing with air pressure,the electron temperature decreases and the electron density increases with the increase of pressure.The intensity of the spectral line increases first and then tends to saturate.Electronic temperature and electronic density will affect the intensity change of spectral line.For the electric law,the voltage of lower frequency has a certain range of decrease,while the voltage at higher frequency will remain near a certain value,and the change of current will be weak.In the process of simulation with the change of air pressure,the concept of electron heating rate is introduced,and it is found that the heating mainly occurs near the sheath layer,and the heating will produce high energy electrons,leading to ionization enhancement,which gives a reasonable explanation for the enhancement of electron density.