Observation of surface nano- structure using EUV phase shift microscope

我们构建了用于光化掩模检测的EUV显微镜（EUVM），该显微镜由Schwarzschild光学系统（NA 0. 3，30 X）和X射线变焦管组成。使用该系统，EUVL成品掩模和Mo/Si玻璃基板进行检测。清晰地观察到6025 Grass掩模上250 nm宽图形的EUVM图像。从该图案可以估计分辨率为50 nm或更小。玻璃基板上的程序化相位缺陷也用于检查。利用EUV显微镜可以观察到宽度为90 nm、100 nm、110 nm的程序化相缺陷，高度为5 nm、长度为400 m □的凸点。同时还观察到了宽100 nm、高2nm的程序化相位缺陷。此外，观察到宽度为500 nm的编程缺陷为两条线。这是因为在编程缺陷的两侧边缘产生了相变。因此，在本研究中，使用EUV显微镜进行了程序相位缺陷的观察，并且成功地观察了多层膜内部的拓扑缺陷图像。这些结果表明，在极紫外显微镜下，可以不依赖于表面形貌，直接获得多层膜的内反射率分布。

We constructed the EUV microscope (EUVM) for actinic mask inspection which consists of Schwarzschild optics (NA0.3, 30X) and X-ray zooming tube. Using this system, EUVL finished mask and Mo/Si glass substrates are inspected. EUVM image of 250nm width pattern on 6025 Grass mask was clearly observed. Resolution can be estimated to be 50nm or less from this pattern. The programmed phase defect on the glass substrate is also used for inspection. By using EUV microscope, programmed phase defect with a width of 90nm, 100nm, 110nm, a bump of 5nm in height and a length of 400m□ can be observed finely. And the programmed phase defect of 100nm-wide and 2nm height pit was also observed. Moreover, a programmed defect with a width of 500nm is observed as two lines. This is because phase change produced with the edge of both sides of a programmed defect. Thus, in this research, observation of a program phase defect was advanced using the EUV microscope, and it succeeded in observation of the topological defect image inside a multilayer film. These results show that it is possible to catch internal reflectance distribution of multilayer under the EUV microscope, without being dependent on surface figure.