20 September 2013 Reflecting on inspectability and wafer printability of multiple EUV mask absorbers
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Abstract
Four EUV film stacks are prepared and evaluated from multiple points of view: mask fabrication, blank inspection, nonactinic inspection, actinic inspection and wafer print. Mask linearity measurements show very good results for all of four blanks. Blank inspection results reveal similar inspectability. Blank roughness and reflectivity at 193nm wavelength were also measured. Some types of defects were evaluated with both non-actinic inspection tools and simulations. It was found that the thinner low reflectivity (LR) stack shows higher defect sensitivity than the thicker ones for pattern defects at 193nm inspection wavelengths. Phase defect evaluations indicate that thinner total film stacks (LR plus absorber) have an advantage for phase defect detection. Defect printability was evaluated through focus by imaging on an EUV microscope and defect printability was shown to be equivalent among the four stacks. Then the appropriate film stacks are discussed from the wafer point of view. Finally the appropriate stack was chosen based on evaluations from all the various points of view.
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Kazunori Seki, Karen Badger, Emily Gallagher, Gregory McIntyre, Toshio Konishi, Yutaka Kodera, Satoshi Takahashi, Vincent Redding, "Reflecting on inspectability and wafer printability of multiple EUV mask absorbers", Proc. SPIE 8880, Photomask Technology 2013, 88800S (20 September 2013); doi: 10.1117/12.2027054; https://doi.org/10.1117/12.2027054
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