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Proceedings Paper

Investigation of EUV mask defectivity via full-field printing and inspection on wafer
Author(s): Rik Jonckheere; Dieter Van Den Heuvel; Fumio Iwamoto; Nickolay Stepanenko; Alan Myers; Matt Lamantia; Anne-Marie Goethals; Eric Hendrickx; Kurt Ronse
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Paper Abstract

Full-field printing on the ASML Alpha Demo Tool, followed by wafer inspection on a KLA-T 2800, is used to qualify typical defectivity levels of EUV reticles. Mask defects are found as repeaters among multiple dies on wafer. The uniform pattern consists of dense lines and spaces. In a first reticle with 40nm linewidth, high levels of natural defects have been found of which a relatively large share was considered as multilayer (ML) type defects, because they printed as rings. Simulation of ML defects could explain this printing behavior as a function of height, size and slope. The main parameter determining the printing behavior of a ML defect is its height. A local distortion of the upper part of the ML, as thin as ~2nm can already print. On-reticle analysis of the ring defects by SEM showed that the defects are present on the absorber, which already explains the printing result. Yet, still several other defects were found to print on the wafer, whereas they were not visible on the reticle and considered local distortions of the ML. Printing results with a second version of the mask that additionally includes programmed multilayer defects with 3nm height confirmed the pronounced printing impact of ML defects as they were simulated. Encouragingly low numbers of natural defects have been found on a third reticle. With this reticle also a first correlation has become possible between the defect maps obtained from wafer inspection, (direct) mask inspection, and blank inspection. This is a viable method to highlight potential gaps between the capability of these tools and printability of defects.

Paper Details

Date Published: 11 May 2009
PDF: 12 pages
Proc. SPIE 7379, Photomask and Next-Generation Lithography Mask Technology XVI, 73790R (11 May 2009); doi: 10.1117/12.824268
Show Author Affiliations
Rik Jonckheere, IMEC (Belgium)
Dieter Van Den Heuvel, IMEC (Belgium)
Fumio Iwamoto, IMEC (Belgium)
Nickolay Stepanenko, IMEC (Belgium)
Alan Myers, IMEC (Belgium)
Matt Lamantia, IMEC (Belgium)
Anne-Marie Goethals, IMEC (Belgium)
Eric Hendrickx, IMEC (Belgium)
Kurt Ronse, IMEC (Belgium)


Published in SPIE Proceedings Vol. 7379:
Photomask and Next-Generation Lithography Mask Technology XVI

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