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Proceedings Paper

Performance of actinic EUVL mask imaging using a zoneplate microscope
Author(s): Kenneth A. Goldberg; Patrick P Naulleau; Anton Barty; Senajith B. Rekawa; Charles D. Kemp; Robert F Gunion; Farhad Salmassi; Eric M. Gullikson; Erik H. Anderson; Hak-Seung Han
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Paper Abstract

The SEMATECH Berkeley Actinic Inspection Tool (AIT) is a dual-mode, scanning and imaging extreme-ultraviolet (EUV) microscope designed for pre-commercial EUV mask research. Dramatic improvements in image quality have been made by the replacement of several critical optical elements, and the introduction of scanning illumination to im-prove uniformity and contrast. We report high quality actinic EUV mask imaging with resolutions as low as 100-nm half-pitch, (20-nm, 5× wafer equivalent size), and an assessment of the imaging performance based on several metrics. Modulation transfer function (MTF) measurements show high contrast imaging for features sizes close to the diffraction-limit. An investigation of the illumination coherence shows that AIT imaging is much more coherent than previously anticipated, with σ below 0.2. Flare measurements with several line-widths show a flare contribution on the order of 2-3% relative intensity in dark regions above the 1.3% absorber reflectivity on the test mask used for these experiments. Astigmatism coupled with focal plane tilt are the dominant aberrations we have observed. The AIT routinely records 250-350 high-quality images in numerous through-focus series per 8-hour shift. Typical exposure times range from 0.5 seconds during alignment, to approximately 20 seconds for high-resolution images.

Paper Details

Date Published: 30 October 2007
PDF: 12 pages
Proc. SPIE 6730, Photomask Technology 2007, 67305E (30 October 2007); doi: 10.1117/12.746756
Show Author Affiliations
Kenneth A. Goldberg, Lawrence Berkeley National Lab. (United States)
Patrick P Naulleau, Lawrence Berkeley National Lab. (United States)
Anton Barty, Lawrence Livermore National Lab. (United States)
Senajith B. Rekawa, Lawrence Berkeley National Lab. (United States)
Charles D. Kemp, Lawrence Berkeley National Lab. (United States)
Robert F Gunion, Lawrence Berkeley National Lab. (United States)
Farhad Salmassi, Lawrence Berkeley National Lab. (United States)
Eric M. Gullikson, Lawrence Berkeley National Lab. (United States)
Erik H. Anderson, Lawrence Berkeley National Lab. (United States)
Hak-Seung Han, SEMATECH (United States)


Published in SPIE Proceedings Vol. 6730:
Photomask Technology 2007
Robert J. Naber; Hiroichi Kawahira, Editor(s)

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