Background: Conventional scanning electron microscopy (SEM) that is used for 2D top-view metrology, a classical line edge roughness (LER) measurement technique, is incapable of measuring 3D structures of a nanoscale line pattern. For LER measurements, SEM measurement generates a single line-edge profile for the 3D sidewall roughness, although the line-edge profile differs at each height in the 3D sidewall. Aim: To develop an evaluation method of SEM-based LER measurement techniques and to verify how the 3D sidewall shape is reflected in the SEM’s 2D result. Approach: Direct comparison by measuring an identical location of a line pattern by SEM and an atomic force microscopy (AFM) with the tip-tilting technique that is capable of measuring the 3D sidewall. The line pattern has vertical stripes on the sidewall due to its fabrication process. Measured line edge profiles were analyzed using power spectral density, height-height correlation function, and autocorrelation function. Results: Line edge profiles measured by SEM and AFM were well matched except for noise level. Frequency and scaling analyses showed that SEM profile contained high noise and had lost a property of self-affine fractals in contrast to AFM. Conclusions: In the case of the line pattern with vertical stripes on the sidewall, SEM profile is generally consistent with 3D sidewall shape. The AFM-based LER measurement technique is useful as LER reference metrology to evaluate other LER measurement techniques.

中文翻译：

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通过SEM和计量倾斜原子力显微镜直接比较线边缘粗糙度的测量结果，以进行参考计量

背景技术：用于2D顶视图计量的传统扫描电子显微镜（SEM）是一种经典的线边缘粗糙度（LER）测量技术，无法测量纳米级线图案的3D结构。对于LER测量，尽管3D侧壁中的每个高度的线边缘轮廓都不同，但SEM测量会为3D侧壁粗糙度生成单个线边缘轮廓。目的：开发一种基于SEM的LER测量技术的评估方法，并验证3D侧壁形状如何在SEM的2D结果中得到反映。方法：使用能够测量3D侧壁的尖端倾斜技术，通过SEM和原子力显微镜（AFM）测量线条图案的相同位置来进行直接比较。线图案由于其制造工艺而在侧壁上具有垂直条纹。使用功率谱密度，高度-高度相关函数和自相关函数来分析测量的线边缘轮廓。结果：除噪声水平外，通过SEM和AFM测量的线边缘轮廓非常匹配。频率和定标分析表明，与AFM相比，SEM轮廓包含高噪声并且失去了自仿射分形的特性。结论：对于在侧壁上带有垂直条纹的线型，SEM轮廓通常与3D侧壁形状一致。基于AFM的LER测量技术可用作LER参考度量衡，以评估其他LER测量技术。通过SEM和AFM测量的线边缘轮廓除噪声水平外均匹配良好。频率和定标分析表明，与AFM相比，SEM轮廓包含高噪声并且失去了自仿射分形的特性。结论：对于在侧壁上带有垂直条纹的线型，SEM轮廓通常与3D侧壁形状一致。基于AFM的LER测量技术可用作LER参考度量衡，以评估其他LER测量技术。通过SEM和AFM测量的线边缘轮廓除噪声水平外均匹配良好。频率和定标分析表明，与AFM相比，SEM轮廓包含高噪声并且失去了自仿射分形的特性。结论：对于在侧壁上带有垂直条纹的线型，SEM轮廓通常与3D侧壁形状一致。基于AFM的LER测量技术可用作LER参考度量衡，以评估其他LER测量技术。