Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope

Journal Article · Tue Jul 12 00:00:00 EDT 2016 · Journal of Micro/Nanolithography, MEMS, and MOEMS

DOI:https://doi.org/10.1117/1.JMM.15.3.033501· OSTI ID:1379419

Benk, Markus P. ^[1]; Wojdyla, Antoine ^[1]; Chao, Weilun ^[1]; Salmassi, Farhad H. ^[1]; Oh, Sharon R. ^[1]; Wang, Yow-Gwo ^[1]; Miyakawa, Ryan H. ^[1]; Naulleau, Patrick P. ^[1]; Goldberg, Kenneth A. ^[1]

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1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

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 in this paper 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. Finally, the anamorphic images show the same image quality in the horizontal and vertical directions.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1379419
• Journal Information: Journal of Micro/Nanolithography, MEMS, and MOEMS, Vol. 15, Issue 3; ISSN 1932-5150
• Publisher: SPIE
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
47 OTHER INSTRUMENTATION
photomasks
extreme ultraviolet
microscopes
extreme ultraviolet lithography
semiconducting wafers
modulation
scanners
multilayers
nickel
fiber optic illuminators