Aerial Image Mask Inspection System for Extreme Ultraviolet Lithography

概要

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We constructed an extreme ultraviolet microscopy (EUVM) system for actinic mask inspection that consists of Schwarzschild optics and an X-ray zooming tube. Using this system, a finished extreme ultraviolet lithography (EUVL) mask and Mo/Si glass substrates were inspected. An EUVM image of a 100-nm-width pattern on a 6025 glass mask was clealy observed. The resolution was estimated to be 50 nm or less from this pattern. The programmed phase defect on the glass substrate was also used for inspection. By using the EUV microscope, a programmed phase defect with widths of 90, 100, and 110 nm, a bump of 5 nm and a length of 400 μm was observed finely. The programmed phase defect of a 100-nm-wide and 2-nm-deep pit was also observed. Thus, in this research, the observation of a programmed phase defect was advanced using the EUV microscope, which succeeded in observing a topological defect structure image of a multilayer film. These results show that it is possible to detect the internal reflectance distribution of a multilayer film under the EUV microscope, without depending on surface pertubation.
2007-09-30