Quantitative linewidth measurement down to 100 nm by means of optical dark-field microscopy and rigorous model-based evaluation
Quantitative linewidth measurement down to 100 nm by means of optical dark-field microscopy and rigorous model-based evaluation
复制标题
通过光学暗视野显微镜和严格的基于模型的评估进行低至 100 nm 的定量线宽测量
DOI：
10.1088/0957-0233/18/2/s15
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发表时间：
2007
影响因子：
2.4
通讯作者：
W. Mirandé
中科院分区：
文献类型：
--
作者：
G. Ehret;B. Bodermann;W. Mirandé
PTB 开发的采用交替掠入射紫外线照明 (UV-AGID) 的暗视野显微镜方法现在可以测量低至 100 nm 的横向结构。与明场显微镜相比，这种新的暗场方法的优点是边缘定位更好，因为只有被物体细节散射或衍射的光才能到达图像平面。此外，在 AGID 显微镜的情况下，邻近效应大大减少。该方法可用于微米和纳米结构的尺寸测量，例如在晶圆、掩模或蚀刻的硅结构上。然而，只有通过将测量数据与经过调整的严格模拟进行比较，才能从显微镜图像中定量确定线宽。为了模拟图像中的强度分布，我们利用两种不同的严格光栅衍射理论。一方面，我们使用严格耦合波分析（RCWA）方法（用于计算衍射电场和磁场），另一方面，我们使用有限元方法（FEM）。特别是，将讨论照明的偏振以及梯形线和空间的边缘角度对显微镜图像的影响。此外，还将介绍 COG 掩模上铬线（COG：玻璃上的铬结构）的不同定量测量。结果将与电子光学测量进行比较。
The dark-field microscopy method with alternating grazing incidence UV illumination (UV-AGID) developed at the PTB now offers the possibility of measuring lateral structures down to 100 nm. The advantage of this new dark-field method is, in comparison to bright-field microscopy, the better edge localization, since only light that is scattered or diffracted by object details reaches the image plane. Also, in the case of AGID microscopy, the proximity effects are much more reduced. This method can be used for dimensional measurements of micro- and nanostructures, e.g. on wafers, masks or etched Si structures. Determining the linewidth quantitatively from the microscope image is, however, only possible by comparing the measured data with adapted rigorous simulations. To model the intensity distribution in the image, we make use of two different rigorous grating diffraction theories. On the one hand we use the rigorous coupled wave analysis (RCWA) method (for calculations of the diffracted electrical and magnetic fields), on the other hand, the finite elements method (FEM). In particular, it will be discussed what influence the polarization of the illumination and the edge angles of the trapezoidal-shaped lines and spaces have on the microscope image. Also, different quantitative measurements of chromium lines on a COG mask (COG: chromium structures on glass) will be presented. The results will be compared with electron optical measurements.