Observation of surface nano- structure using EUV phase shift microscope

我们搭建了用于光化掩模检测的极紫外光显微镜(EUVM)，它由Schwarzschild光学系统(NA0.3，30X)和X射线变焦管组成。利用该系统对EUVL成品掩模和Mo/Si玻璃基板进行了检测。在6025Grass掩模上观察到250 nm宽的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位相缺陷也用于检查。利用EUV显微镜可以很好地观察到宽度为90 nm、100 nm、110 nm、高度为5 nm、长度为400m的程序性相缺陷。并观察到宽100 nm、高2 nm的程序性位相缺陷。此外，观察到宽度为500 nm的程序性缺陷为两条线。这是因为相变产生于程序化缺陷的两侧边缘。因此，在本研究中，利用EUV显微镜对程序相缺陷进行了观察，并成功地观察到了多层膜内部的拓扑缺陷图像。这些结果表明，在EUV显微镜下可以捕捉到多层膜的内部反射分布，而不依赖于表面形状。

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.