周期结构的衍射模拟算法及其应用研究

发布时间：2018-04-10 06:01

本文选题：散射度量　切入点：严格耦合波分析　出处：《电子科技大学》2015年博士论文

【摘要】：散射度量是半导体微电子制造领域中工艺过程控制与关键尺寸(CD)测量的重要技术手段,它广泛应用于微电子制造领域。根据2011年国际半导体技术蓝图(ITRS)规划,散射度量作为一种在线、实时、无损、高性价比的计量手段,将在新的技术节点,对新材料或新结构的量测发挥重要作用。周期结构的衍射模拟算法是散射度量的重要部分,切实影响着其测量的实时效率。因此衍射模拟算法的研究、改进与应用,是本文的工作重点。本文工作基于国家重大专项子课题——光学关键尺寸(OCD)检测系统产业化的横向课题展开,是实现OCD技术软件部分的关键。算法方面,以严格耦合波分析法的改进与层吸收法结合严格耦合波分析法的重构(傅里叶模态层吸收法)为重点;应用方面以OCD软件平台的衍射模拟算法模块的构建为重点,相关的给出一种基于散射度量应用的层间错位测试方法。主要内容为:1.综合当前严格耦合波分析法的各类研究成果,全面给出了其实现过程,并将之作为核心算法实施于OCD软件的算法模拟模块。主要包括典型结构的介电系数函数的Toeplitz矩阵的构造方法、特征问题矩阵的构造方法(Lalanne经验法与法向矢量法)、阶梯近似下的多层结构传输矩阵法、应用对称技术的矩阵削减法。其中对称技术的实现过程通过介绍课题组研究成果(小角度近似严格耦合波分析法)给出。同时,以上所有方法均应用于本文所述傅里叶模态层吸收法中。2.基于严格耦合波分析法,介绍了一种针对具有任意可解析边界的典型周期结构的快速法向矢量场构造方法,并给出其经验性的优选原则。对一些典型周期结构本方法能相对于非优选的法向矢量场与Lalanne经验法进一步提高2阶左右收敛。3.结合严格耦合波分析法与层吸收法,给出了傅里叶模态层吸收法的完备实现过程。改进原层吸收法中的串联倍速算法,提出了两类全场/散射场模型下的源形式,并分析了它们区别,最后通过数值分析归纳出一种适用于傅里叶模态层吸收的空间步长选择原则。对于垂直侧壁薄层结构严格耦合波分析法的计算效率约为傅里叶模态层吸收法的2倍;对于严格耦合波分析法中阶梯近似层数与傅里叶模态层吸收法的网格数相当的情况,后者计算效率则远远高于前者。同时傅里叶模态层吸收法避免了对特征值问题这一个难以并行分解的耗时过程的计算,更适合实施于具有并行计算单元(GPU)架构的计算平台。4.综合本文研究的衍射模拟算法,详细说明了OCD软件模拟算法模块的实现过程;通过优选测试的空间角度和优选衍射光关注参数,提出一种快速高精度的层间错位测试方法。
[Abstract]:Scattering measurement is an important technique for process control and CD-measurement in semiconductor microelectronics manufacturing field. It is widely used in the field of microelectronics manufacturing.According to the 2011 International Semiconductor Technology Blueprint (ITRSs), scattering measurement, as an on-line, real-time, lossless, cost-effective measurement method, will play an important role in the measurement of new materials or structures in the new technology node.The diffraction simulation algorithm of periodic structure is an important part of scattering measurement, which affects the real time efficiency of measurement.Therefore, the research, improvement and application of diffraction simulation algorithm are the focus of this paper.This paper is based on the national major sub-project, Optical critical size (OCD) detection system industrialization of the horizontal project, is the key to achieve the OCD technology software part of the key.In the aspect of algorithm, the improvement of strict coupling wave analysis method and the reconstruction of layer absorption method combined with strict coupling wave analysis method (Fourier mode layer absorption method) are emphasized, and the construction of diffraction simulation algorithm module based on OCD software platform is emphasized.A method for measuring interlayer dislocation based on scattering measurement is proposed.The main content is: 1.Based on the current research results of rigorous coupled wave analysis, the implementation process is presented, which is used as the core algorithm in the algorithm simulation module of OCD software.It mainly includes the construction method of Toeplitz matrix of dielectric coefficient function of typical structure, the construction method of characteristic problem matrix such as Lalanne's empirical method and normal vector method, the multilayer structure transfer matrix method under ladder approximation, and the matrix reduction method using symmetry technique.The realization process of symmetry technology is given by introducing the research results of the research group (small angle approximate rigorous coupled wave analysis method).At the same time, all the above methods are applied to the Fourier modal layer absorption method described in this paper.Based on the strictly coupled wave analysis method, a fast normal vector field construction method for typical periodic structures with arbitrary analytic boundaries is introduced, and the empirical optimal selection principle is given.For some typical periodic structures, this method can further improve the convergence of order 2 by 3. 3 compared with the non-optimal normal vector field and Lalanne empirical method.The complete realization of the Fourier modal layer absorption method is presented by combining the rigorous coupled wave analysis method with the layer absorption method.By improving the cascade doubling algorithm in the original layer absorption method, two kinds of source forms under the full-field / scattering field model are proposed, and the differences between them are analyzed.Finally, a spatial step selection principle for Fourier modal layer absorption is concluded by numerical analysis.The computational efficiency of the rigorous coupled wave analysis method for the thin layer structure of vertical lateral wall is about 2 times that of the Fourier modal layer absorption method, and for the case where the number of ladder approximate layers is equivalent to the grid number of the Fourier modal layer absorption method in the strictly coupled wave analysis,The computational efficiency of the latter is much higher than that of the former.At the same time, the Fourier modal layer absorption method avoids the computation of the eigenvalue problem, which is a time-consuming process difficult to decompose in parallel, and is more suitable for the computing platform .4with a parallel computing unit (GPU) architecture.Based on the diffraction simulation algorithm studied in this paper, the realization process of the simulation algorithm module of OCD software is explained in detail, and a fast and high precision measurement method of interlayer dislocation is proposed by optimizing the spatial angle of the test and the optimized parameters of diffraction light.
【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TN305

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