Specular spectral profilometry on metal layers
Specular spectral profilometry on metal layers
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金属层的镜面光谱轮廓测量
DOI：
10.1117/12.386454
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
J. Bendik
中科院分区：
文献类型：
--
作者：
Junwei Bao;Xinhui Niu;Nickhil H. Jakatdar;C. Spanos;J. Bendik
随着深亚微米半导体技术的出现，金属互连的测量变得更加关键。除了线路宽度外，还需要有关高度和侧壁轮廓的信息，以确保良好的电路性能。传统的计量工具，如CD扫描电子显微镜和原子力显微镜，要么无法测量轮廓，要么太慢，无法进行生产过程控制。散射法是一种很有前途的原位、全剖面测量工具。在该方法中，宽带光在周期结构(240 nm到760 nm)上的散射被用有限系列的傅立叶展开项近似来模拟。通过在预计算库中比较各种可能的轮廓的测量光谱和模拟光谱，可以提取轮廓。前人的工作已经在抗蚀剂结构上取得了良好的效果。然而，对于金属结构，需要包括更多的衍射级才能准确地模拟光散射。在这项研究中，使用31阶产生了0.22微米线和0.44微米空间金属栅构型库。利用该库对相同尺寸的金属栅结构进行了轮廓提取。我们的数据表明，CD-SEM和基于散射的轮廓提取之间的相关性似乎与轮廓的侧壁角度有关。我们将对这些差异进行分析和讨论。
With the advent of deep sub-micron semiconductor technology, metrology for metal interconnects becomes more critical. In addition to the line width, information about the height and the sidewall profile is needed to ensure good circuit performance. Conventional metrology tools such as CD SEMs and AFMs are either unable to measure the profile, or too slow for production process control. Scatterometry is a promising candidate as in situ, full-profile metrology tool. In this method, scattering of broadband light (240 nm to 760 nm) on periodical structures is simulated by approximating the structure with a finite series of Fourier expansion terms. By comparing the measured spectrum and the simulated spectra for various possible profiles in a precalculated library, the profile can be extracted. Previous work has shown good results on resist structures. For metal structures, however, more diffraction orders need to be included to accurately simulate light scattering. In this study, a library for 0.22 micrometer line and 0.44 micrometer space metal grating structures is generated using 31 orders. The profiles of metal grating structures of the same size are extracted using this library. Our data shows that the correlation between CD-SEM and scatterometry-based profile extraction appears to be related to the sidewall angle of the profile. These discrepancies will be analyzed and discussed.