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Proceedings Paper

Sub 50 nm cleaning-induced damage in EUV mask blanks
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Paper Abstract

Defects are still one of the main challenges of extreme ultraviolet (EUV) mask blanks. In particular, a majority(~75%) of substrate defects are nanometer size pits. These pits are usually created during final surface polishing of the synthetic, quartz glass substrates. This study presents data that indicates cleaning may also induce pits in the substrate surface. These pits are typically 20 nm and larger, and are contained in a circular area on the surface, which is scanned by a megasonic nozzle during cleaning. Concentrated collapse of cavitation bubbles in the areas scanned by megasonic is expected to be one of the main mechanisms of pit creation. The data indicates the existence of a hard surface layer with an estimated thickness of approximately 30 to 60 nm, which is resistive to pit creation. After this layer is removed, the number of pit defects present on the substrate increases dramatically with megasonic cleaning. It is also demonstrated that, within the detection limits of the atomic force microscope (AFM), the size of a pit does not change due to cleaning.

Paper Details

Date Published: 1 April 2008
PDF: 8 pages
Proc. SPIE 6921, Emerging Lithographic Technologies XII, 692120 (1 April 2008); doi: 10.1117/12.774951
Show Author Affiliations
Abbas Rastegar, SEMATECH, Inc. (United States)
Sean Eichenlaub, SEMATECH, Inc. (United States)
Vivek Kapila, SEMATECH, Inc. (United States)
Arun John Kadaksham, SEMATECH, Inc. (United States)
Pat Marmillion, SEMATECH, Inc. (United States)
IBM (United States)


Published in SPIE Proceedings Vol. 6921:
Emerging Lithographic Technologies XII
Frank M. Schellenberg, Editor(s)

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