等离子体浸没离子注入论文：等离子体浸没离子注入 充电效应 PIC

1、【关键词】等离子体浸没离子注入 充电效应PIC-MCC模型 混 合PIC圆柱形介质圆管【英文关键词】Plasma Immersion Ion ImplantationCharging effects Particle In Cellplus Monte CarloCollision(PIC/MCC)model Hybrid PIC Cylindrical dielectric tube等离子体浸没离子注入论文:等离子体浸没离子注入介质靶 鞘层特性的粒子模拟研究【中文摘要】等离子体浸没离子注入(plasma immersion ion implantation,简称Pill)是在传统的束线离子注

2、入(PBII)的基础上提 出的一种新的离子注入技术，由于其具有成本低、设备简单、易操作、 适合处理复杂形状样品等诸多优点，在材料表面改性、半导体和微电 子材料加工等方面得到广泛的应用。然而,由于介质材料的导电性能 较差,在对介质材料进行表面改性时容易出现注入离子电荷在表面积 累的现象，出现充电效应,从而导致注入离子能量达不到预期负脉冲 电压幅值,严重影响注入效果；同时，对于空心圆柱形介质圆管的内表 面的离子注入过程，除了充电效应，随着离子注入过程的进行，介质圆 管内的鞘层不断向圆管中心扩展，鞘层在圆管中心会出现重叠现象， 导致离子的注入剂量和注入能量降低。为了解决上述问题，对介质靶 PIII过

3、程中鞘层演化特性进行理论上的深入研究就显得尤为必要。因 为注入材料表面的离子主要是在鞘层中获得加速，鞘层特性直接影响 被加工材料的离子注入效果，同时，理论研究的结果可以揭示离子注 入过程的物理机理，为实际离子注入工艺的优化提供一定的参考。本 文主要采用粒子模拟(particle in cell,简称PIC)方法，对介质靶材 料等离子体浸没离子注入过程中的鞘层演化规律和靶表面的离子注 入特性进行了模拟研究，分析讨论了各种参数对PIII过程中鞘层演化 和注入特性的影响。本论文的具体安排如下：第一章，介绍了 pm技 术的特点及其发展应用、pm技术在平板介质靶和圆管介质靶的应用 研究现状及意义，综述了

4、对pm过程进行计算机模拟时常用到的模拟 方法。第二章，对等离子体模拟中使用的PIC/MCC模拟方法进行了详 细的介绍，把PIC/MCC分成PIC和MCC两个部分进行讲述。同时，结合 本文要用到的算法,在讨论模型时对一维平板模型和柱坐标下的二维 模型都做了相应的推导。第三章，采用二维混合PIC(Hybrid PIC)的 方法对介质圆管内表面的PIII过程进行了数值模拟，得到了空间鞘层 演化的规律,并且对离子注入剂量和注入能量均匀性的进行了讨论。 结果显示：在介质圆管内表面PIII过程中，随着积累电荷的增多，充电 效应越来越明显，导致介质表面的电势降低，注入能量减小；其次，离 子注入剂量在介质圆管

5、内表面的分布不均匀，在介质圆管管口附近位 置注入剂量明显偏大。当介质圆管内离子完全注入到介质内表面后， 由于管口外端离子还会继续注入到管口内表面，随着注入时间的增加, 这种不均匀性变得越来越严重。因此，在介质圆管内离子完全注入到 内壁前结束一个脉冲周期就变得尤为必要；最后，适当延长金属电极 的长度，可以有效的提高介质圆管内表面离子注入剂量和离子注入能 量的均匀性。第四章,我们针对混合PIC在处理短脉冲PIII中的不足 (假设电子满足波尔兹曼分布，从而忽略了电子的运动和效应对离子 注入的影响)，采用完全自洽的一维PIC/MCC模型对一维平板介质靶P III过程进行了模拟。该模型完全跟踪电子和离子

6、的运动轨迹，对带电 粒子运动过程中与中性气体间的碰撞过程及介质表面的二次电子发 射过程进行了全面的考虑；同时讨论了介质厚度和气体压强对注入过 程的影响。结果表明，为了获得较好的注入效果,应该尽量采用较薄的 介质、短的脉冲上升时间和低的放电气压。【英文摘要】Plasma immersion ion implantation (PII) is a new ion implantation technology based upon the traditional ion-beam ion implantation (PBII) technology, as PII has many advanta

7、ges such as low costs, simple equipment, easily operation and is capable to process the work-piece with complex shape. Presently, PIII technology has been widely used in the modification of materials, semiconductor treatment, and microelectronic materials processing, etc. However, when treating the

8、dielectric substrate with PIII, the implanted ions can accumulate at the dielectric surface owing to the low electric conductivity of the dielectric materials, and this result in the charging effects. So the implanted ions cari t get the full acceleration with the same amplitude of the applied negat

9、ive pulse. What s more, with the time extend, the converging plasma sheaths from the inner surfaces of the cylindrical dielectric tube could get overlapping in the central axis, the implanted dose and energy decrease further. In order to solve these problems, it is necessary to sduty theoretically t

10、he sheath evolution near the inner of the cylindrical dielectric tube during the PH processing. Because the implanted ions mainly get acceleration from the plasma sheath, the characteristics of the plasma sheath directly affect the final properties of the target materials after P III process. With t

11、he theoretical investigation, the physical mechanism of ion implantation can be revealed, and the results can give some guidance for the optimization of an actual P I process.In this thesis, we adopt the particle-in-cell method to study the principles of the sheath expansion and implantation charact

12、eristics in PHI process with a dielectric target. The influences of many parameters on the PHI are discussed. The thesis is organized as:In Chapterl, we briefly introduce the characteristics and applications of PHItechnology, the current research state and significance of thePill in flat and cylindr

13、ical dielectric materials, and also review the investigation methods of computer simulation for P III. In Chapter2, we give a detailed description about the Particle-In-Cell plus Monte Carlo Collision (PIC/MCC) method which is used in plasma computer simulation. We divide the PIC/MCC method into two

14、 parts, and introduce the PIC and MCC method, respectively. At the same time, we also make a corresponding derivation of the one-dimension flat plate model and two-dimension cylindrical model.In Chapter3, the sheath expansion near the inner surface of a cylindrical dielectric tube is investigated by

15、 using a two-dimension hybrid PIC model. The influence of experimental parameters (such as the metal electrode length and dielectric thickness) on the uniformity of implanted ions dose and energy along the inner surface of the dielectric tube is analyzed and discussed. It finds that during the Pi pr

16、ocess, as there are increasingly amount of charges accumulate on the dielectric surface, the charging effect become much more significant, leading a lower surface potential and lower implanted energy. Secondly, with a finite length cylindrical dielectric tube, the distribution of theimplanted ion do

17、se along the inner surface is nonuniform, the implanted dose near the top of the bore is much bigger than the other region. When all the ions inner the tube get implanted, many ions originate from outside of the bore continued to implant into the inner surface, this make the nonuniformity of the imp

18、lanted dose more serious. So, it is very important for improving the implanted dose uniformity to end a single pulse period before all of the ions in the tube get exhaust. At last, the implanted ions energy distribution uniformity along the inner surface of the dielectric tube can been improved by u

19、sing a longer metal electrodeIn Chapter4, In order to overcome the shortage of hybrid PIC in the simulation of a nanosecond pulse Pill (in the hybrid PIC model, electrons are supposed to be Boltzmann s distribution and thus lack the movement effect of electrons to Pill), we employ a self-consistent

20、PIC/MCC model to study Pill to PET substrate. With the model, ions and electrons are both dynamically traced simultaneously. The various collision processes of electrons collision and the secondary electron emission (SEE) on the surface of PET substrate are included. We have studied the influence of

21、 the thickness of dielectric film and the gas pressure on IH. Thesimulation results demonstrate that it is necessary to use a lower pressure and thinner PET substance to get better Pill property in Pill of dielectric film.【日录】等离子体浸没离子注入介质靶鞘层特性的粒子模拟研究 摘要 4-6 Abstract 6-71 引言 10-201.1 等离子体浸没离子注入技术及其发展应用10-141.1.1等离子体浸没离子注入技术10-121.1.2等离子体浸没离子注入技术的发展及