借助光刻成像仿真软件的μDBO穿线套刻标记  

Research on wafer stage overlay-μDBO targets by lithography imaging simulation software

作　　者：陈天元 周钰颖 高安 CHEN Tianyuan;ZHOU Yuying;GAO An(Front-end System and Integration Engineering Department,Shanghai Micro Electronics Equipment Group Co.,Ltd.,Shanghai 201203,China;Metrology Equipment Department,Shanghai Micro Electronics Equipment Group Co.,Ltd.,Shanghai 201203,China;Shanghai Key Laboratory of Lithographic Optics and Inspection,Shanghai 201203,China)

机构地区：[1]上海微电子装备(集团)股份有限公司,前道系统集成部,上海201203 [2]上海微电子装备(集团)股份有限公司,量测产品部,上海201203 [3]上海市光刻光学与检测重点实验室,上海201203

出　　处：《清华大学学报（自然科学版）》2023年第12期2057-2075,共19页Journal of Tsinghua University(Science and Technology)

摘　　要：在光刻机的对准、曝光和量测等过程中,存在量程范围小,测量精度要求极高的套刻标记。这些套刻标记在实现特定功能的同时,会受到多种误差的影响,比如标记线宽与设计差异、标记线条边缘粗糙度、标记边缘效应等。该文旨在解决光刻套刻量测领域中的问题,特别是针对业界常用的微型衍射套刻(micro diffraction-based overlay,μDBO)标记,通过对穿线套刻情形进行量测过程的仿真研究,提出了一种借助光刻成像仿真软件进行标记量测结果仿真的方法。该文运用自制代码的DrM软件和商业仿真软件HyperLith作为工具,两者的仿真结果均定性还原了实验中探测到的特殊亮暗线现象,验证了该方法用于量测仿真的可行性。此外,该文还对匹配实验仪器的穿线套刻μDBO标记设计、照明波长、照明配置和待测信号区域等参数进行仿真优化,输出了基于目前实验配置的优化标记与方案。[Objective] Overlay targets with a small range and requiring extremely high measurement accuracy are used in the lithography system's alignment, exposure, and measurement processes. They are inevitably affected by many errors when performing specialized functions, e.g., line width and design difference, line edge roughness, and target edge effect. This paper conducts a simulation study on the micro diffraction-based overlay target(μDBO) in the condition of wafer stage overlay(WSO), which is commonly used in lithography, based on the design of overlay alignment targets in the field of measurement. Litho-target design simulation software is known to be more advanced than lithographic imaging simulation software, but its license is usually rarer and more expensive. We propose a novel method for simulating lithography target metrology results using lithography imaging simulation software. The method predicts the detected light intensity distribution in the experiment qualitatively and can calculate target performance in metrology. [Methods] This paper compares the similarities between metrology process imaging in the optical method and lithography imaging. In the metrology process imaging simulation, the target, lens, and imaging sensor modules have analogs in the lithography simulation, which are the mask, lens, and aerial image modules. Thus, metrology target patterns can be represented as mask patterns, and the output of an aerial image from lithography simulation software can be analyzed to obtain metrology information. We use WSO-μDBO targets, which have two different critical dimensions and suffer from a heavy marginal effect in experiments. The self-made DrM software in Matlab code with the rigorous couple wave analysis(RCWA) algorithm and the commercial program HyperLith with the finite-difference time-domain algorithm are used as tools to restore the phenomenon in the experiment. Both programs import the illumination patterns of the experimental instruments as well as the structures of WSO-μDBO targets. T

关 键 词：计算光刻 光刻成像仿真软件 微型衍射套刻标记 穿线套刻 

分 类 号：V231.2[航空宇航科学与技术—航空宇航推进理论与工程]