【作者】 陈兆权；

【导师】 刘明海； 胡希伟； 文远芳；

【作者基本信息】 华中科技大学 ， 脉冲功率与等离子体， 2010， 博士

【摘要】 近年来,在大规模集成电路和液晶显示器的制造过程中,大面积等离子体源成为必需；微电子器件制作工序的刻蚀、灰化和等离子体化学气相沉积等迫切需要空间均匀的、高电子密度及高活性化的等离子体源。此外,多晶硅薄膜、金刚石薄膜、碳纳米管等的生成,大面积高密度等离子体源同样充当重要角色。在众多等离子体源中,平板型表面波等离子体(SWP)源是一种有希望同时满足以上苛刻要求的优良等离子体源。因此,大面积高密度SWP的开发及应用研究受到了前所未有的关注,目前研究的重点在于解决高效放电和大面积空间均匀性问题。本论文涉及表面波等离子体的产生机理、实现途径、参数特性和数值仿真等四个方面的研究内容,具体工作如下：1.根据高密度等离子体和金属在与高频电磁波相互作用时表现出的类似特性,提出高密度等离子体与介质分界面处存在表面等离子体激元偏振(SPPs)现象。采用SWP简正模型,分析了表面电磁波的空间分布特性,探讨了高密度等离子体中SPPs的特征参量,特别是带有密度梯度层的表面电场局域增强效应的半解析证明,从机理上探讨了SWP的产生机制。2.根据矩形波导管内的微波分布,确定了波导管宽壁面开槽位置,结合SWP源的结构尺寸,设计了开槽天线阵列。为了达到高效耦合微波能量和稳定表面波放电的目的,根据谐振腔理论和偶极子近场辐射理论设计了单模谐振腔阵列和亚波长衍射光栅,与开槽天线阵列一起构造了高效波模转换器件,这是产生大面积高密度均匀稳定表面波等离子体的核心器件。3.搭建带有多模谐振腔的SWP源装置,验证了高密度SWP的产生确实是基于SPPs所携带的表面电磁波维持了稳定放电。改用高效波模转换器进行放电实验,200W低功率输入下,等离子体密度为1.04×1018 m-3,空间均匀性达85.7%,微波吸收率为95%,功效比为4.4 cm2／W。此外,产生的等离子体具有双麦克斯韦电子能量分布和参数稳定可控性,使得综合性能在同类源中处于世界领先。4.采用非自洽均匀冷等离子体模型研究了开槽天线激发表面波场的空间分布特性,利用自洽混合模型得出了等离子体参数的空间分布特性,与实验结果相一致,证实了SWP是表面加热和参数扩散分布的事实。用高频电磁仿真软件(HFSS, CST),得出了表面波的空间分布及时空演化过程,解释了表面波放电的实验现象,为下一代超大面积SWP源的建立提供了坚实的工程依据和有益借鉴。更多还原

【Abstract】 During the past several years, for ultra-large scale integration or liquid crystal display panel manufacturing, large-area plasma sources are needed. In fabricating the electronic devices, such as etching, ashing or plasma chemical vapor deposition, the spatial uniformity of plasma sources are strongly required; besides overdense electrons and radicals are also required. Furthermore, in the fabrication of amorphous or crystalline silicon films, diamond film synthesis and carbon nanotube growth, the large-area overdense plasma source has also been useful. Among the various plasma devices, the planar-type surface-wave plasma (SWP) source is an advanced plasma source, which is a type of the promising plasma source satisfying the above rigorous requirements for the large-area plasma processing. Therefore, the development and application researches of the large-scale overdense SWP have attracted the unprecedented attentions. Furthermore, the current focus of the study is addressed on the efficient discharge and the spatial uniformity in large area.Mainly four aspects of the research contents in this thesis, in the context of which are related to generation mechanism, achievement channel, parameter character and numerical simulation, are described specifically as follows:1. According to the similar characteristics of overdense plasma and metal interacting with high-frequency electromagnetic waves, the surface plasmon polaritons (SPPs) placed at the interface between overdense plasmas and dielectric is proposed. The generation mechanism of SWP is studied by analyzing the simplified SWP model, from which the spatial distribution characteristics of the surface electromagnetic waves are analyzed, the characteristic parameters of SPPs in overdense plasma are discussed, and especially the semi-analytical confirmation about the local electrical field enhancement in the interlayer with density gradient is presented.2. According to the microwave field distributed in the rectangular waveguide, the position of the cavern slot on the width waveguide wall is determined. Combining with the structure size of the SWP source, novel slot-array antennas are exploited. In order to achieve the purpose of coupling microwave energy efficiently and surface-wave discharge stably, in addition based on the resonant chamber theory and the dipole near-field radiation theory, the single-mode resonant chamber array and the subwavelength diffraction grating are designed, respectively. All those three parts consist of an efficient wave mode conversion device, which is the hard core of the SWP device to generate uniform and stable large area overdense plasmas. 3. The production of overdense SWP is verified as a stable discharge excited by surface electromagnetic waves which is carried by SPPs indeed, through experimenting on the SWP source with a multi-mode resonant chamber. By experimenting on the plasma source with the efficient wave mode conversion device, plasma density of 1.04×1018 m-3, spatial uniformity up to 85.7%, microwave absorption rate of 95% and efficiency ratio of 4.4 cm2/W are obtained under the lower input power of 200 W. Adding the bi-Maxwellian electron energy distribution and the stability and controllability of the plasma parameters, the overall performance of the proposed SWP occupy the global leader position in comparison with the similar sources.4. The spatial distribution of the surface wave excited by slot antennas is studied using a non-self-consistent uniform cold plasma model. The spatial distribution of the plasma parameters are simulated by using the self-consistent hybrid model, meanwhile the SWP with the characters of surface heating and plasma parameter diffusing effect is confirmed in comparing with the results of experimental measurement. The spatial distribution and the spatio-temporal evolution of the surface waves are arrived at by adopting the high-frequency electromagnetic simulation software (HFSS, CST), which explain the experimental phenomenon of the surface-wave discharge. The fruits achieved in numerical simulation provide the solid engineering basis and the useful reference for the construction of the next super-area SWP source.更多还原