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Proceedings Paper

Surface modification of EUVL mask blanks by e-beam
Author(s): Arun John Kadaksham; Thomas Laursen; Timothy Owen; Jon Underwood; Abbas Rastegar
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Paper Abstract

Mask inspection review of pattern features and defects is normally carried out using a secondary electron microscopy (SEM) technique. Ideally, such mask inspections reviews should be non-destructive; nonetheless, as reported in this paper, high-dose exposures of EUVL mask surfaces have resulted in significant topographical changes, which were revealed by topographical mapping of reviewed masks using atomic force microscopy (AFM). Exposures with current densities of 1 mA/cm2 and higher resulted in the formation of topographical features in and around the scanned region on mask surfaces. On the Ru-capped multilayer blanks, the topographies consisted of small or absent depressions surrounded by ridges, which were attributed to secondary-electron-emission induced hydrocarbon deposition. On the chromium-nitride backsides, the topographies were usually simple depressions - although sometimes ridges were observed. The depressions were attributed to volume compaction in the substrate. The depressions were attributed to volume compaction in the substrate, and were observed for all for mask surfaces studied - substrate compaction took place with both quartz and LTEM substrates. The height range of the topography extended up to 25 nm, whereas the lateral dimensions often exceeded the scanned area by about a micron. While these lateral extensions could not be explained by either beam-induced heating or stress relief, Monte-Carlo simulations showed that it could be explained qualitatively by the size of the region within which the energy deposition had taken place. This interpretation suggests that the current understanding as described by Hau- Riege qualitatively describe our observations related to depression topography.

Paper Details

Date Published: 20 April 2011
PDF: 16 pages
Proc. SPIE 7971, Metrology, Inspection, and Process Control for Microlithography XXV, 79710X (20 April 2011); doi: 10.1117/12.879452
Show Author Affiliations
Arun John Kadaksham, SEMATECH North (United States)
Thomas Laursen, ASML US, Inc. (United States)
Timothy Owen, SEMATECH North (United States)
Jon Underwood, SEMATECH North (United States)
Abbas Rastegar, SEMATECH North (United States)

Published in SPIE Proceedings Vol. 7971:
Metrology, Inspection, and Process Control for Microlithography XXV
Christopher J. Raymond, Editor(s)

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