Articles

Surface modification of extreme-ultraviolet lithography mask blanks by e-beam

[+] Author Affiliations
Arun John Kadaksham

SEMATECH, 257 Fuller Road, Albany, New York 12203

Thomas Laursen

ASML, 320 Ushers Road, Clifton Park, New York 12065

Timothy Owen, Jon Underwood, Abbas Rastegar

SEMATECH, 257 Fuller Road, Albany, New York 12203

J. Micro/Nanolith. MEMS MOEMS. 10(4), 043015 (December 08, 2011). doi:10.1117/1.3655725
History: Received April 29, 2011; Revised July 15, 2011; Accepted September 02, 2011; Published December 08, 2011; Online December 08, 2011
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A mask inspection review of pattern features and defects is normally carried out using a secondary electron microscopy technique. Ideally, such mask inspection reviews should be nondestructive; nonetheless, as reported in this paper, high-dose exposures of extreme-ultraviolet mask surfaces have resulted in significant topographical changes, which were revealed by topographical mapping of reviewed masks using atomic force microscopy. 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, and were observed for all four mask surfaces studied, substrate compaction took place with both quartz and low thermal expansion material substrates. The height range of the topography extended up to 25 nm, whereas the lateral dimensions often exceeded the scanned area by about a micrometer. 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 describes our observations related to depression topography.

© 2011 Society of Photo-Optical Instrumentation Engineers (SPIE)

Citation

Arun John Kadaksham ; Thomas Laursen ; Timothy Owen ; Jon Underwood and Abbas Rastegar
"Surface modification of extreme-ultraviolet lithography mask blanks by e-beam", J. Micro/Nanolith. MEMS MOEMS. 10(4), 043015 (December 08, 2011). ; http://dx.doi.org/10.1117/1.3655725


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