DC Discharge Studies Using PIC-MCC
DC Discharge Studies Using PIC-MCC
复制标题
使用 PIC-MCC 进行直流放电研究
DOI：
--
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
J. Verboncoeur
中科院分区：
文献类型：
--
作者：
J. Hammel;J. Verboncoeur
直流放电，无论是磁化的还是非磁化的，都用于等离子体处理，用于溅射薄膜沉积、离子注入和其他处理。本研究的目的是将直流放电的理论分析与使用单元内粒子与蒙特卡罗碰撞(PIC-MCC)方法得到的结果进行比较。PIC-MCC用于精确模拟直流放电中存在的动力学过程，包括带电粒子与均质麦克斯韦中性分子的碰撞。对材料加工感兴趣的参数，如阴极处的离子能量和角分布，可以使用PIC获得。PIC-MCC模拟和分析的交叉验证可用于改进计算模型和分析模型。提出了完善基础理论的几点建议。本文所研究的直流放电是指方位对称的非磁化放电。一根圆柱形的绝缘管由电极绑在两端。使用直流电源驱动放电。电介质壁包含径向的等离子体。以氩气和氦气为原料气体。在实验室直流放电中，气体击穿的临界电压是极板之间的距离和气体压力的函数。经过一段过渡时间后，观察到了稳态密度和阴极下落距离。如果对暂态行为不感兴趣，PIC-MCC方法更实际的做法是从合理接近稳态的密度分布开始。对磁化和未磁化的径向直流放电也进行了研究。在这种结构中，等离子体被限制在r=r1的阴极和r=r2的阳极之间，其中r2和r1。±ẑ法线边界采用周期边界和介电边界条件。这些配置类似于用于等离子体处理的圆柱形放电。用PIC对几种直流放电进行了模拟，并与理论结果进行了比较。对1D-3V和2D-3V两种模型进行了模拟。讨论了二维效应。讨论了PIC模型与理论模型存在差异的可能原因，并对改进理论提出了建议，以更准确地与动力学结果进行比较，并克服了以前模型的假设。
DC discharges, both magnetized and unmagnetized, are used in plasma processing for sputtering film deposition, ion implantation, and other processes. The objective of this study is to compare theoretical analysis of a DC discharge with results obtained using the particle in cell with Monte Carlo collisions (PIC-MCC) method. PIC-MCC is used to accurately model kinetic processes present in DC discharges, including charged particle collisions with homogeneous Maxwellian neutral molecules. Parameters of interest to materials processing, such as the ion energy and angular distribution at the cathode, may be obtianed using PIC. Cross-validation of PIC-MCC simulation and analysis may be used to improved both computational and analytic models. Suggestions for the improvement of basic theory are presented. DC discharges of interest in this study are azimuthally symmetric unmagnetized discharges. A cylindrical insulating tube is bound on the ends by electrodes. A DC power source is used to drive the discharge. A dielectric wall contains the plasma in the radial direction. Argon and helium were used as feedstock gases. In laboratory DC discharges, gas breakdown is seen at a critical voltage as a function of the distance between the plates and gas pressure. After a transient period, a steady state density and cathode fall distance are observed. If the transient behavior is not of interest, it is more practical for the PIC-MCC method to start with a density profile reasonably close to steady state. Radial DC discharges, both magnetized and unmagnetized, were also studied. In this configuration, the plasma is confined between a cathode at r = r1 and an anode at r = r2, where r2 > r1. Periodic and dielectric boundary conditions were used for the ±ẑ-normal boundaries. These configuations resemble cylindrical discharges as used for plasma processing. Several DC discharges are simulated with PIC and the results compared with theory. Both 1d-3v and 2d-3v models are simulated. Two dimensional effects are discussed. Possible reasons for differences between the PIC and theoretical model are discussed and suggestions are made for the improvement of the theory to more accurately compare to the kinetic results and overcome previous assumptions of the model.