Numerical Study On Ionization And Density Uniformity In ECR Plasma

With the development of low-temperature plasma technology, electron cyclotron resonance, which has advantages of no electrode contamination, low pressure operation, high plasma density, gradually becomes one of research topics. In ECR plasma, ionization can affect the characteristics of plasma; uniformity of plasma density can affect the quality of etching and thin film deposition. Thus, it is meaningful to study ionization and uniformity of plasma density. Besides, metastable atoms has important contribution to ionization and excitation. The study of the effect of metastable atoms on ionization and uniformity of plasma density is significant.The research object of this paper is microwave electron cyclotron resonance source. Using Maxwell equation, we established mathematical model of the magnetic field produced by the magnetic field coils. Then we got the numerical results of magnetic field by solving the model. On the background of the magnetic field, basing on theory of magnetic fluid, under drift-diffusion approximation, we established two 2-D fluid models, including no metastable atoms and considering metastable atoms, for the plasma in the chamber of electron cyclotron resonance plasma source. A finite difference method is used for self-consistent numerically simulating the models. Numerical results of the characteristics of ECR plasma are obtained. From the analysis and comparison of numerical results from two models, the effects of operational parameters of ECR plasma, including background gas pressure, microwave power and current in magnetic field coil, and metastable atoms on ionization and uniformity of the plasma density are researched.In the first chapter, the theory of ECR plasma technique, the applications of ECR plasma, the situation of study on ECR plasma are introduced. From the theory to the practice, our knowledge of ECR plasma is more comprehensive. Besides, we can see from this chapter that the research of ionization and density uniformity in ECR plasma is less, and the study of metastable atoms in ECR plasma is hardly any. Therefore, our work is meaningful.In the second chapter, ionization and density uniformity in ECR plasma, especially the effects of operational parameters of ECR plasma on ionization and density uniformity, are discussed as important aspects. The numerical model of ECR plasma, no metastable atoms, is established in detail, including basic equations, boundary conditions, initial conditions and numerical method.In the third chapter, the numerical model including metastable atoms is presented briefly. We got some numerical results. Comparing with the results from the second chapter, we mainly analyzed the effects of metastable atoms on ionization and uniformity of plasma density. We have a clearer knowledge of contribution of metastable atoms in ECR discharge by the research of this part.Finally, conclusions and the future work are given in the last chapter.