全方位离子注入柱形几何碰撞鞘层时空演化数值解

对使用流体力学碰撞模型研究全方位离子注入柱形翅等离子体鞘层时空演化的求解过程进行了详细的讨论，得到了数值计算结果。     

空心圆管端点附近等离子体源离子注入过程中鞘层的时空演化

等离子体源离子注入过程中，鞘层的演化规律直接影响到离子注入到材料中的深度进而影响材料表面的性质和结构，对材料的不同部位这种影响是不同的.利用无碰撞两维流体动力学模型，研究了有限上升时间的电压脉冲作用下，共轴放置附加零电极的半无限空心圆管端点附近等离子体源离子注入过程中，鞘层的时空演化规律.通过计算得到了鞘层内随时间变化的电势分布和离子密度分布，计算了端点附近材料表面处的离子流密度分布和注入剂量分布随时间的变化规律.计算机模拟结果显示了空心圆管内部、外部及端点表面处的离子流密度分布和注入剂量分布存在很大差异.     

等离子体源离子注入鞘层随时空演化的数值模拟

在等离子体源离子注入装置中(PSⅡ),靶被直接放入均匀等离子体源中,并在其上加负高压脉冲,从而使靶的周围形成了一个只存在离子的等离子体鞘层,离子以较高速度注入靶中。利用冷流体方程和泊松方程组成的非线性方程组对一维平面几何鞘层时空演化过程进行数值模拟,所采用的负高电势脉冲波形为方波和梯形波,得到了电子密度、离子密度、电势分布的时空演化曲线,并首次对梯形波下降沿时间内鞘层时空演化作了详细讨论。     

介质靶表面的充电效应对等离子体浸没离子注入过程中鞘层特性的影响

针对等离子体浸没离子注入技术在绝缘体表面制备硅薄膜工艺，采用一维脉冲鞘层模型描述介质靶表面的充电效应对鞘层厚度、注入剂量及靶表面电位等物理量的影响.数值模拟结果表明：随着等离子体密度的增高，表面的充电效应将导致鞘层厚度变薄、表面电位下降以及注入剂量增加，而介质的厚度对鞘层特性的影响则相对较小. 关键词： 等离子体浸没离子注入 脉冲鞘层 绝缘介质 充电效应     

有限尺寸方靶等离子体离子注入动力学的三维粒子模拟研究

采用三维粒子模拟模型研究了有限尺寸方靶等离子体浸没离子注入过程中的鞘层动力学行为,得到了鞘层尺寸和方靶表面的注入剂量、注入能量以及注入角度等信息,并与二维无限长方靶注入结果进行了对比.模拟结果表明,与无限长方靶不同,有限尺寸方靶周围鞘层很快扩展为球形,但鞘层厚度明显减小.在模拟的50ω^-1_pi时间尺度内靶表面注入剂量很不均匀,中心区域注入剂量最小,四个边角附近位置注入剂量最大.这种剂量不均匀性是由于鞘层扩展为球形,使得鞘层内离子被聚焦并注入到边角附 关键词： 等离子体浸没离子注入 数值模拟 三维粒子模拟 有限尺寸方靶     

表面凹陷对等离子体浸没离子注入均匀性的影响

利用二维流体模型和数值计算方法模拟了等离子体浸没离子注入（ＰⅢ）Ｋ ,具有圆弧凹槽的平面靶周围的鞘层扩展情况,计算了鞘层扩展过程中的电热分布、离子速度和离子密度变化获得了沿靶表面的离子入射角度和注入剂量的分布情况,为等离子体浸没离子注入处理复杂形状靶提供了理论基础。     

脉冲偏压上升沿特性对等离子体浸没离子注入鞘层扩展动力学的影响

等离子体浸没离子注入(PIII)是用于材料表面改性的一种廉价高效、非视线的技术.采用等离子体粒子模型，通过假设电子密度服从Boltzmann分布，求解Poisson方程和Newton方程，跟踪离子在等离子体鞘层中的运动形态及特性并进行统计分析，研究了不同上升速率和形状的6种波形上升沿对鞘层时空演化、离子注入能量和剂量的影响.结果表明，在PIII过程中，脉冲上升沿影响了等离子体鞘层的扩展，且不同波形诱导的鞘层厚度间存在最大差值.电场强度在鞘层的外边缘区域存在陡降区，离子的运动为非匀加速过程.可以通过调整脉冲 关键词： 等离子体浸没离子注入 鞘层 粒子模型 上升沿     

ƽ��ֱ����ƫѹ��ײ�ʲ�Child-Langmuir���ɵ���Ϲ�ʽ

采用流体动力学模型研究了离子与中性粒子的电荷交换碰撞效应对直流偏压鞘层厚度的影响。对于平板鞘层,结果表明随着碰撞参数的增大,鞘层厚度明显地变小。根据数值结果,给出了碰撞情况下的Child-Lang-muir定律的拟合式。研究了柱形和球形靶的靶半径对鞘层厚度的影响。     

含杂质多离子成分等离子体中的碰撞鞘结构

采用流体模型，研究含杂质多离子成分等离了体的碰撞鞘，首衔导出描述碰撞鞘的非线性方程组，然后采用数值方法研究鞘宽和离子注入能量与等离子体参数的信赖关系，结果表明，碰撞率及杂质（尘埃）密度对鞘宽和离子注入能量有显著影响。     

半圆形容器等离子体源离子注入过程中离子动力学的两维PIC计算机模拟

利用两维particle-in-cell方法研究了半圆形容器表面等离子体源离子注入过程中鞘层的时空演化规律. 详尽考察了鞘层内随时间变化的电势分布和离子密度分布规律,离子在鞘层中的运动轨迹和运动状态,得到了半圆容器内、外表面和边缘平面上各点离子注入剂量分布规律,获得了工件表面各点注入离子的入射角分布规律. 研究结果揭示了半圆容器边缘附近鞘层中离子聚焦现象,以及离子聚焦现象导致工件表面注入剂量分布和注入角度分布存在很大不均匀的基本物理规律. 关键词： 等离子体源离子注入 鞘层 两维particle-in-cell方法 离子运动轨迹     

On the collisional transient sheath

A theory of the transient sheath spanning the entire range of ion collisionality and treating finite rise-time voltage pulses is developed. This theory predicts the maximum ion impact energy, and the temporal dependence of the sheath width, the ion impact energy, and the ion flux. It is found that the ion impact energy is greatly reduced by even small amounts of collisionality, whereas the sheath width and ion flux at the target (i.e., ion current density) are relatively insensitive to collisionality. In the collisional sheath, the maximum ion impact energy is found to decrease with increasing rise time and collisionality. Good agreement is found between the theory and fluid simulations. In particular, the collisional dependence of the ion impact energy is well described by the theory     

Comparison of the directional characteristics of swift ion excitation for two small biomolecules: glycine and alanine

The characteristics of ions that enter the plasma sheath with an oblique incident angle have been investigated in the presence of an external magnetic field. The ion dynamics in a collisional and collisionless magnetized plasma sheath have been numerically calculated by using a fluid model. Several values for the ion velocity at the sheath edge, orientation and strength of the magnetic field and the ion-neutral collision frequency have been considered. The results show that in a collisionless magnetized plasma sheath, the behaviour of ions that obliquely enter the sheath with some specific velocities at the sheath edge and at some specific orientations and strengths of magnetic field, is more complicated than that of ions with normal entrance angles. For the oblique entrance of ions, the weak magnetic fields cause some fluctuations in ion velocity around its boundary value, i.e. the ion velocity does not accelerate. However, the numerical calculations show that the ion dynamics in a collisional magnetized plasma sheath are the same for both normal and inclined entrance of ions into the sheath.     

Effect of charge exchange collisions on the static properties of afully collisional ion sheath

The effect of charge exchange collisions on the properties of a fully collisional, static ion sheath is considered. The existing collisional law, which excludes the effect of electrons, is derived from the fluid equations. The effect of electrons are later considered and an approximate power law solution for the potential is obtained. The effect of collisionality on the sheath properties is discussed. The approximate power law solution, derived with the help of fluid equations, is applied to find the ion energy distribution at the electrode     

Reactor modeling of magnetically enhanced capacitive RF discharge

Magnetic and collisional effects on capacitive radio frequency (RF) discharges for magnetically enhanced reactive ion etching (MERIE) are investigated. Using simplified plasma and sheath models, a collisional magnetic-sheath equation that governs the sheath dynamics under a de magnetic field crossed with a sinusoidal RF electric field is obtained. The sheath equation includes global effects of the bulk plasma. Together with the power-balance equation and the particle-conservation equation, the sheath equation is used to extract a circuit model and predict the electrical behavior of MERIE reactors. Numerical results on the plasma density and the power in MERIE reactors agree well with reported experimental results and the circuit model describes the repeated discharge properties well     

外加磁场对碰撞射频鞘层离子能量分布的影响

采用双流体模型,数值研究入射到射频鞘层偏压电极上的离子能量分布.研究结果表明：磁场在改变离子运动状态的同时,调控着基板上的离子能量分布,使之在垂直基板方向和平行基板方向间转移. 关键词： 等离子体 射频 鞘层 磁场     

Dynamics of a collisional ion sheath

Experiments on collisional ion sheaths are carried out by applying a pulsed negative bias on a disc electrode immersed in a collisional plasma. The pulse is characterized by a linear rise, followed by a constant voltage phase and then exponential decay. The measured currents to the electrode are compared to predictions from a dynamic collisional ion sheath model which is developed from the basic two fluid equations. The parameter determining the degree of collisionality is also defined. The agreement between the two in the rising and the flat top phases of the pulse is found to be good. Some residual discrepancies as well as the disagreement in the decay phase are discussed.     

Experimental studies of plasma sheath near meshes of different transmissivity

<正>The measurements of the potential distributions in the boundary layer near meshes with different mesh spacing were conducted in weakly collisional plasmas using a fine-structured emissive probe and the results of the sheath thickness and electric field at the sheath-presheath edge were compared with theoretical models of collisional presheath and collisionless sheath.It was shown that,because the meshes are partially transparent to ions,the sheath is thinner and the electric field is stronger for the mesh of higher transmissivity,owing to the increased ion density in the sheath contributed from the ions transmitted from the other side of the mesh.However,the potential profiles in the presheath remain almost the same for different meshes except for the shift of the sheath-presheath edge.The thickness of the sheath decreases while the electric field at the edge increases with the increase of the neutral gas pressure.Furthermore, depending on the pressure,the measured electric fields at the edge are close to that from the models of a transition region.     

衬底偏压对ECR等离子体鞘层和离子行为的影响

介绍了电子回旋共振微波放电等离子体中离子向衬底输运的蒙特卡罗模型,该模型考虑了精确依赖于离子能量的电荷交换和动量转移截面以及中性区与鞘层的衔接。     

The effects of ion-neutral collision frequency on the plasma sheath dynamics for oblique entrance of ions into the sheath

Recently it has been shown that the magnetic field has significant effects on the characteristics of ions which enter the collisionless plasma sheath with an oblique incidence angle. Here, we have investigated these effects in collisional plasma sheath. Considering the ion-neutral collision, the basic equations of fluid model in a plasma sheath have been numerically solved in the presence of an external magnetic field where the ion collision frequency has a power law dependency to the ion flow velocity. The results show that the effects of magnetic field on the plasma sheath dynamics strongly depend on the ion-neutral collision frequency and its dependency to ion flow velocity.     

Self-consistent nonlinear resonance and hysteresis of a charged microparticle in a RF sheath

A self-consistent model is proposed to study nonlinear phenomena, such as secondary resonance and hysteresis in the vertical oscillations of a charged microparticle in a radio-frequency sheath. The motion of a single microparticle in the sheath is simulated by solving Newton's equation in which various forces acting on the particle are taken into account. The particle charging and the sheath electric field are described by a self-consistent model of the collisional radio-frequency sheath dynamics. It is found that the nonlinearity is related to the particle's charge, the sheath electric field, and the external excitation force, as well as the ion drag force and neutral-gas friction on the particle.