容性耦合硅烷等离子体尘埃颗粒空间分布的二维流体模拟

Two-dimensional fluid simulation of spatial distribution of dust particles in a capacitively coupled silane plasma

基于自主研发的二维流体尘埃模型,研究了射频容性耦合硅烷等离子体放电中不同腔室结构对尘埃颗粒密度空间分布的影响.模拟发现,有别于一维模型,径向电场和作用在尘埃颗粒上的离子拖拽力径向分量是导致尘埃颗粒密度分布径向不均匀的主要因素,使其在极板边缘处呈现两个局部峰值,其中一个峰值表明尘埃颗粒有可能会克服电场力的支撑更接近极板.在极板半径较小或极板间距较小的情况下,径向离子拖拽力的作用增强,使尘埃颗粒更易于在极板边缘处和腔室侧壁附近聚集,出现环状尘埃颗粒分布带.在放电极板有介质材料包裹的情况下,尘埃颗粒密度径向分布的均匀性得到改善.最后,还模拟了单个尘埃颗粒在极板边缘处的涡旋运动规律.

In this work,we develop a two-dimensional fluid model to study the spatial density distributions of dust particles in a radio frequency capacitively coupled silane plasma.Unlike those scenarios based on the one-dimensional fluid model,in this work,the nonuniformity of the radial density distributions of dust particles is attributed mainly to the radial components of the electric field force and the ion drag force acting on the dust particles,leading to the two local density peaks near the electrode edges.It seems that dust particles tend to overcome the support of the electric field force and move much closer to the electrodes,as one of the density peaks indicates.Moreover,with the decrease of the radii of the discharge electrodes or the distance between them,the radial component of the ion drag force is enhanced,resulting in more dust particles gathering near the electrode edge region,and forming a ring-shaped particle density distribution.In the case of the discharge electrodes wrapped with dielectric materials,the uniformity of the radial density distributions of dust particles between the two electrodes is improved.Finally,the vortex motion of a single dust particle near the electrode edge region is also simulated in this work.