Understanding the influence of three-dimensional sidewall roughness on observed line-edge roughness in scanning electron microscopy images

IF 1.5 2区 物理与天体物理 Q3 ENGINEERING, ELECTRICAL & ELECTRONIC
L. van Kessel, T. Huisman, C. W. Hagen
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引用次数: 3

Abstract

Abstract. Background: Line-edge roughness (LER) is often measured from top-down critical dimension scanning electron microscope (CD-SEM) images. The true three-dimensional roughness profile of the sidewall is typically ignored in such analyses. Aim: We study the response of a CD-SEM to sidewall roughness (SWR) by simulation. Approach: We generate random rough lines and spaces, where the SWR is modeled by a known power spectral density. We then obtain corresponding CD-SEM images using a Monte Carlo electron scattering simulator. We find the measured LER from these images and compare it to the known input roughness. Results: For isolated lines, the SEM measures the outermost extrusion of the rough sidewall. The result is that the measured LER is up to a factor of 2 less than the true on-wafer roughness. The effect can be modeled by making a top-down projection of the rough edge. Our model for isolated lines works fairly well for a dense grating of lines and spaces as long as the trench width exceeds the line height. Conclusions: In order to obtain and compare accurate LER values, the projection effect of SWR needs to be taken into account.
了解三维侧壁粗糙度对扫描电镜图像中观察到的线边缘粗糙度的影响
摘要背景:线边缘粗糙度(LER)通常是从自上而下的临界尺寸扫描电子显微镜(CD-SEM)图像来测量的。在这种分析中,侧壁的真实三维粗糙度通常被忽略。目的:模拟研究CD-SEM对侧壁粗糙度(SWR)的响应。方法:我们生成随机的粗线和空间,其中SWR由已知的功率谱密度建模。然后,我们使用蒙特卡罗电子散射模拟器获得相应的CD-SEM图像。我们从这些图像中找到测量的LER,并将其与已知的输入粗糙度进行比较。结果:对于孤立的线条,扫描电镜测量了粗糙侧壁的最外层挤压。结果是,测量到的LER比真实的晶圆上粗糙度小2倍。这种效果可以通过对粗糙边缘进行自上而下的投影来建模。我们的隔离线模型对于密集的线和空间光栅效果相当好,只要沟槽宽度超过线的高度。结论:为了获得和比较准确的LER值,需要考虑SWR的投影效应。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
3.40
自引率
30.40%
发文量
0
审稿时长
6-12 weeks
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