梯形管内壁等离子体离子注入鞘层扩展MATLAB-PIC数值模拟

基于MATLAB利用Particle-in-cell模型,对梯形管内壁等离子体离子注入过程,进行了二维数值模拟.计算结果表明在中心电极附近出现了"阳极鞘层",该鞘层内部不存在离子,而且在鞘层边缘离子密度最高.在上下管壁上的离子注入剂量呈现"m"形分布.通过对注入过程中等离子体密度分布和不同时间段管壁不同位置离子注入剂量的跟踪,发现"阳极鞘层"扩展行为是导致"m"形分布的原因.由于梯形管形状的不对称性,"阳极鞘层"的边缘向梯形长底方向扩展较快.在注入初始时刻离子注入的能量很低,随着时间延长离子能量逐渐升高,这是由离子初始位置决定的.可见梯形管自身形状决定了鞘层形状和最终的离子注入能量和剂量分布.

PIC Simulation of Plasma Ion Implantation into Inner Surface of Trapezoid Tube Using MATLAB

Numerical simulation on plasma ion implantation of a trapezoid tube is conducted in a MATLAB based Particle-in-cell model.It shows that "anodic-sheath" appears around internal electrode,where there is no ion.Some ions gather at the edge of "anodic-sheath" leading to a high-ion-density ring.It makes an m-shaped dose distribution on upside wall and downside wall of the tube.Due to asymmetry of the trapezoid tube,"anodic-sheath" expands faster toward long-wall of the tube.Implantation energy is relatively low at initial stage and becomes higher with time.This is attributed to the position of ions in the tube before they are implanted into the tube wall.The tube configuration determines sheath shape and final distribution of implantation dose and energy.