薄膜沉积反应腔室多场建模及轮廓调控方法研究

发布时间：2018-06-18 22:42

本文选题：PECVD + 多场耦合　；参考：《清华大学》2015年博士论文

【摘要】：薄膜沉积工艺是半导体制造、MEMS、表面工程等领域的基础工艺。等离子体增强化学气相沉积(PECVD)是重要的薄膜沉积工艺方法之一,其工艺系统涉及复杂多场耦合及化学反应过程。目前PECVD反应腔室设计与工艺调控的研究普遍依赖经验试错与大量的工艺参数试验,不仅需要大量的时间与物力成本,且复杂的工艺过程没有得到揭示。实质上,设备的工艺参数是影响薄膜沉积工艺性能的表象因素,其深层次的因素是物质、能量的空间分布(称之为工艺因素轮廓)。本文着眼于反应腔室的多场特性及工艺理化过程,从工艺因素轮廓的视角,建立多场耦合工艺系统模型、揭示工艺机理、研究反应腔室设计与工艺调控的新思路新方法。针对300 mm竖直喷淋式PECVD反应腔室,建立流场、热场、等离子体子系统模型,为工艺系统建模及反应腔室设计解决子系统建模中的关键结构特征建模的难点问题。基于子系统模型与实验,研究工艺及结构参数对子系统物理场特性的影响规律。针对PECVD工艺过程,研究工艺多场耦合建模方法,建立包含热流、物质输运、化学反应及等离子体放电过程的工艺系统模型,构建从工艺参数输入到薄膜性能参数输出的工艺过程仿真系统。以SiH4/NH3制备氮化硅薄膜工艺为对象,通过片内薄膜沉积速率及N/Si分布的对比验证工艺系统模型的有效性,并探究工艺过程中物质及能量过程对薄膜沉积速率及N/Si的影响机制,为深入研究反应腔室结构设计及工艺调控提供了模型及理论支撑。针对反应腔室设计与工艺调控的共性问题——轮廓调节问题,建立轮廓误差反馈模型及其求解方法。基于轮廓误差构造设计/控制变量序列的反馈迭代算法,求解已知目标轮廓确定物理空间多自由度的几何结构、介质属性、源、边界条件等逆问题,为多自由度反应腔室设计及控制提供了有效的求解方法。为实现工艺因素空间分布及薄膜性能参数片内分布梯度的精细化调控,提出面向轮廓梯度调控的可控型/阻抗型的反应腔室设计方法,并基于多场模型及轮廓误差反馈模型方法对设计方案进行求解。以非均匀阻抗模块为实施案例,实现了对薄膜沉积速率、折射率、温度轮廓梯度的精细化调节,为大面积高一致性薄膜沉积反应腔室设计与工艺调控提供了一种新的解决方案。
[Abstract]:Thin film deposition is the basic process in semiconductor manufacturing and surface engineering. Plasma enhanced Chemical Vapor deposition (PECVD) is one of the most important process methods for thin film deposition. Its process system involves complex multi-field coupling and chemical reaction processes. At present, PECVD chamber design and process control generally rely on empirical trial and error and a large number of process parameters test, which not only requires a lot of time and material costs, but also the complex process has not been revealed. In essence, the process parameters of the equipment are the apparent factors that affect the properties of the film deposition process, and the deeper factors are the spatial distribution of the material and the energy (which is called the profile of the process factors). This paper focuses on the multi-field characteristics of the reaction chamber and the process of physicochemical process. From the point of view of the outline of the process factors, the model of the multi-field coupling process system is established, the mechanism of the process is revealed, and a new way of thinking about the design and control of the reaction chamber is studied. For the 300mm vertical spray PECVD chamber, the flow field, thermal field and plasma subsystem model are established. The key structural features of the subsystem modeling are solved for the process system modeling and the design of the reaction chamber. Based on the subsystem model and experiment, the influence of process and structure parameters on the physical field characteristics of subsystem is studied. For the PECVD process, the multi-field coupling modeling method is studied, and the process system model including heat flux, mass transport, chemical reaction and plasma discharge process is established. A process simulation system from the input of process parameters to the output of film performance parameters is constructed. Silicon nitride thin films were prepared by SiH _ 4 / NH _ 3. The effectiveness of the system model was verified by comparing the deposition rate and the distribution of N / Si, and the influence mechanism of material and energy process on the deposition rate and N / Si was investigated. It provides a model and theoretical support for the further study of the structure design and process control of the chamber. Aiming at the common problem in the design of reaction chamber and process control, the contour adjustment problem, the contour error feedback model and its solving method are established. A feedback iterative algorithm based on contour error to construct the sequence of design / control variables is used to solve the inverse problems such as geometric structure, medium attribute, source, boundary condition and so on. It provides an effective solution method for the design and control of multi-degree of freedom reaction chamber. In order to realize the fine control of the spatial distribution of process factors and the in-chip distribution gradient of film performance parameters, a controllable / impedance chamber design method for profile gradient control was proposed. The design scheme is solved based on multi-field model and contour error feedback model. Taking the non-uniform impedance module as an example, the fine adjustment of deposition rate, refractive index and temperature profile gradient is realized, which provides a new solution for the design and process control of large area and high consistency film deposition reaction chamber.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB306

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