Observation of the internal defects of multilayer film
We constructed the EUV microscope (EUVM) for actinic mask inspection which consists of Schwarzschild optics (NA 0.3, 30) and X-ray zooming tube. Using this system, EUVL finished mask and Mo/Si coated glass substrates are inspected. EUVM image of 300-nm-wide pattern of finished mask was clearly observed. Resolution can be estimated to be 50nm or less from this pattern. The programmed phase defect on the glass substrate made by HOYA is also used for inspection. By using EUV microscope, programmed phase defect with dot patterns of over 90nm in size and over 4nm-height bump can be observed finely. And the programmed phase defect of 100-nm-wide and 2-nm-depth pit was also observed. Thus, in this research, observation of a programmed phase defect was advanced using the EUV microscope, in other words, it is succeeded in observation of the topological defect image inside a multilayer film. These results show that it is possible to detect internal reflectance distribution of multilayer under the EUV microscope, without being dependent on surface figure.
defect euv microscope mask euv lithography