Study of Critical Dimensions of Printable Phase Defects Using an Extreme Ultraviolet Microscope

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. This system was used to inspect completed extreme ultraviolet lithography (EUVL) masks and Mo/Si coated substrates on ultralow expansion (ULE) glass. We also have fabricated programmed phase defects on the blanks used for inspection. The EUVM system was capable of resolving a programmed line-pit defect with a width of 40 nm and a depth of 10 nm and also that with a width of 70 nm and a depth of 2 nm. However, a 75-nm-wide, 1.5-nm-deep pit defect was not resolved. The EUVM system was also capable of resolving programmed hole-pit defects with widths ranging from 35 to 170 nm and depths ranging from 2.2 to 2.5 nm. However, 20-nm-wide, 1.5-nm-deep hole-pit defects were not resolved. These results agree with the simulation results perfectly. Thus, in this study, critical dimensions of a pit defects on mask blanks were determined to be a width of 20 nm and a depth of 2 nm.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2009-06-25