复杂环境中的纳米光刻对准方法研究

发布时间：2019-01-21 07:05

【摘要】：微电子技术与纳米科技的快速发展不断推动着以光刻为首的微纳加工技术的进步,使其已经成为衡量国家科技核心竞争力的重要标志。作为光刻的关键单元技术之一,对准技术将直接影响套刻结果。当下,最先进光刻机的特征尺寸已经达到了10nm,考虑到对准精度需至少达到光刻分辨力的1/10这一要求,超高精度的光刻对准方法受到了越来越多的重视。基于莫尔条纹的纳米光刻对准方法凭借其超高的对准精度,良好的可靠性和鲁棒性被认为是一项极具应用潜力的对准技术。目前,已经有许多关于该技术的研究成果与文章被报道,但是这些工作都集中在如何提高测量的灵敏度与准确度,而很少有报道涉及环境因素,尤其是对准标记的空间姿态、照明光束的质量和图像处理算法等因素,对光刻对准精度的影响。事实上,莫尔条纹的相位分布与这些因素紧密相连。因此,本论文将主要研究对这些环境因素是如何影响莫尔条纹的相位分布,进而影响对准精度。现将本文所涉及的主要研究内容包括归纳如下:1.综述现行的典型光刻对准技术,并分析其优缺点。旨在挖掘其优势的同时引入光学干涉测量,并提出基于莫尔条纹的纳米光刻对准方法。再通过理论分析和公式推导,指出莫尔条纹对微小位移的放大作用,以及其相位信息与对准偏差之间的对应关系。据此,我们将设计一套粗精结合的光刻对准标记,并给出其对应的图像处理算法和相位提取算法;2.针对精对准方案对高精度和实时性的要求,本文将提出一种基于频谱的加窗傅里叶变换方法,并将利用Maltlab的Window DesignAnalysis Tool平台分析其在提取莫尔条纹相位信息方面的性能表现,其中主要包括抑制频谱泄露的能力和不同窗口函数的性能比较。3.分析面内倾斜对莫尔条纹分布的影响,建立相应的数理模型,并通过数值仿真的方法对提出的理论模型进行验证。在此基础上,进一步给出针对该误差源的矫正方法,然后通过仿真研究比较了其应用范围和性能表现。结果表明,针对面内倾斜的误差矫正方法可达到实现10-6rad量级矫正精度。4.分析光束准直性对莫尔条纹分布的影响,建立相应的数理模型,然后通过数值仿真的方法对提出的理论模型进行验证,最后在此基础上给出针对该误差源的矫正方法。针对矫正算法中对光束准直性的实时性测量要求,提出了基于差动光栅和泰伯效应的光束准直性测量方法,结果表明该方法的测量精度可以达到10-8rad级别。5.在理论研究的基础上,搭建了掩模-硅片对准实验系统。基于该实验平台,采用了步进实验和重复性实验来验证所提出的对准方案的精度。实验结果表明,对准最大误差低于10nm,误差标准差低于5nm,重复对准精度小于30nm(3σ)。
[Abstract]:The rapid development of microelectronic technology and nanotechnology has continuously promoted the progress of micro-nano processing technology led by photolithography, which has become an important symbol to measure the core competitiveness of national science and technology. As one of the key unit techniques of lithography, alignment technology will directly affect the results of lithography. At present, the feature size of the most advanced lithography machine has reached 10 nm. Considering that the alignment accuracy needs to reach at least one tenth of the resolution of lithography, the ultra-high precision lithography alignment method has been paid more and more attention. Nano-lithography alignment based on moire fringes is considered to be a potential alignment technique with high alignment accuracy, good reliability and robustness. At present, many research results and articles on the technology have been reported, but these efforts have focused on how to improve the sensitivity and accuracy of the measurement, and few reports have been made on environmental factors, especially on the spatial attitude of the marking. The effect of illumination beam quality and image processing algorithm on the alignment accuracy of lithography. In fact, the phase distribution of moire fringes is closely related to these factors. Therefore, this paper will focus on how these environmental factors affect the phase distribution of moire fringes and further affect the alignment accuracy. The main contents of this paper are summarized as follows: 1. The current typical lithography alignment techniques are reviewed and their advantages and disadvantages are analyzed. The aim of this paper is to exploit its advantages and to introduce optical interferometry, and a new alignment method based on moire fringes is proposed. Through theoretical analysis and formula derivation, it is pointed out that the effect of Moir 茅 fringe on the amplification of small displacement, and the corresponding relationship between the phase information and the alignment deviation. Based on this, we will design a set of coarse fine lithography alignment mark, and give the corresponding image processing algorithm and phase extraction algorithm. 2. Aiming at the requirement of high precision and real time of precision alignment scheme, a windowed Fourier transform method based on spectrum is proposed in this paper, and its performance in extracting Moir 茅 fringe phase information is analyzed by using Window DesignAnalysis Tool platform of Maltlab. It mainly includes the ability to suppress spectrum leakage and the performance comparison of different window functions. 3. The influence of in-plane tilt on the distribution of moire fringes is analyzed, and the corresponding mathematical model is established, and the proposed theoretical model is verified by numerical simulation. On this basis, the correction method for the error source is given, and the application range and performance are compared by simulation. The results show that the error correction method for in-plane tilt can achieve the correction accuracy of 10-6rad order of magnitude. 4. 4. The influence of beam collimation on the distribution of moire fringes is analyzed, the corresponding mathematical model is established, and the proposed theoretical model is verified by numerical simulation. Finally, a correction method for the error source is given. Aiming at the requirement of real-time measurement of beam collimation in correction algorithm, a new method based on differential grating and Tyber effect is proposed. The results show that the accuracy of the method can reach the 10-8rad level of 5. 5. On the basis of theoretical research, a mask-silicon wafer alignment experiment system is built. Based on the experimental platform, stepwise experiments and repetitive experiments are used to verify the accuracy of the proposed alignment scheme. The experimental results show that the maximum error is less than 10 nm, the error standard deviation is less than 5 nm, and the precision of repeated alignment is less than 30nm (3 蟽).
【学位授予单位】：中国科学院研究生院(光电技术研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TB383.1;TN305.7

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