Lithography

Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope

[+] Author Affiliations
Markus P. Benk, Antoine Wojdyla, Weilun Chao, Farhad Salmassi, Sharon Oh, Yow-Gwo Wang, Ryan H. Miyakawa, Patrick P. Naulleau, Kenneth A. Goldberg

Center for X-ray Optics, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States

J. Micro/Nanolith. MEMS MOEMS. 15(3), 033501 (Jul 12, 2016). doi:10.1117/1.JMM.15.3.033501
History: Received April 6, 2016; Accepted June 20, 2016
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Abstract.  The SHARP high-numerical aperture actinic reticle review project is a synchrotron-based, extreme ultraviolet (EUV) microscope dedicated to photomask research. SHARP emulates the illumination and imaging conditions of current EUV lithography scanners and those several generations into the future. An anamorphic imaging optic with increased mask-side numerical aperture (NA) in the horizontal and increased demagnification in the vertical direction has been proposed to overcome limitations of current multilayer coatings and extend EUV lithography beyond 0.33 NA. Zoneplate lenses with an anamorphic 4×/8× NA of 0.55 are fabricated and installed in the SHARP microscope to emulate anamorphic imaging. SHARP’s Fourier synthesis illuminator with a range of angles exceeding the collected solid angle of the newly designed elliptical zoneplates can produce arbitrary angular source spectra matched to anamorphic imaging. A target with anamorphic dense features down to 50-nm critical dimension is fabricated using 40 nm of nickel as the absorber. In a demonstration experiment, anamorphic imaging at 0.55 4×/8× NA and 6 deg central ray angle (CRA) is compared with conventional imaging at 0.5 4× NA and 8 deg CRA. A significant contrast loss in horizontal features is observed in the conventional images. The anamorphic images show the same image quality in the horizontal and vertical directions.

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© 2016 Society of Photo-Optical Instrumentation Engineers

Citation

Markus P. Benk ; Antoine Wojdyla ; Weilun Chao ; Farhad Salmassi ; Sharon Oh, et al.
"Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope", J. Micro/Nanolith. MEMS MOEMS. 15(3), 033501 (Jul 12, 2016). ; http://dx.doi.org/10.1117/1.JMM.15.3.033501


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