Phase defect observation using an EUV microscope

摘要

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 250 nm width pattern on 6025 Grass mask was clealy observed. Resolution can be estimated to be 50 nm 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 90 nm, 100 nm, 110 nm, a bump of 5 nm and a length of 400 μm can be observed finely. And the programmed phase defect of 100 nm-wide and 2 nm pit was also observed. Moreover, a programmed defect with a width of 500 nm 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.