Paper
20 October 2006 Multilayer defects nucleated by substrate pits: a comparison of actinic inspection and non-actinic inspection techniques
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Abstract
The production of defect-free mask blanks remains a key challenge for EUV lithography. Mask-blank inspection tools must be able to accurately detect all critical defects whilst simultaneously having the minimum possible false-positive detection rate. We have recently observed and here report the identification of bump-type buried substrate defects, that were below the detection limit of a non-actinic (i.e. non-EUV) inspection tool. Presently, the occurrence of pit-type defects, their printability, and their detectability with actinic techniques and non-actinic commercial tools, has become a significant concern. We believe that the most successful strategy for the development of effective non-actinic mask inspection tools will involve the careful cross-correlation with actinic inspection and lithographic printing. In this way, the true efficacy of prototype inspection tools now under development can be studied quantitatively against relevant benchmarks. To this end we have developed a dual-mode actinic mask inspection system capable of scanning mask blanks for defects (with simultaneous EUV bright-field and dark-field detection) and imaging those same defects with a zoneplate microscope that matches or exceeds the resolution of EUV steppers.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
A. Barty, K. A. Goldberg, P. Kearney, S. B. Rekawa, B. LaFontaine, O. Wood II, J. S. Taylor, and H.-S. Han "Multilayer defects nucleated by substrate pits: a comparison of actinic inspection and non-actinic inspection techniques", Proc. SPIE 6349, Photomask Technology 2006, 63492M (20 October 2006); https://doi.org/10.1117/12.686742
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Cited by 6 scholarly publications and 4 patents.
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KEYWORDS
Inspection

Photomasks

Extreme ultraviolet

Reflectivity

Multilayers

Signal detection

Imaging systems

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