1 August 2016 Anisotropic shadow effects with various pattern directions in an anamorphic high numerical aperture system
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Abstract
A high numerical aperture (NA) system with an NA larger than 0.5 is required to make patterns of 1X nm and below, even though extreme ultraviolet lithography uses a 13.5-nm wavelength source. To avoid the reflective efficiency loss and to avoid an increase in the chief ray angle of incident light, use of an anamorphic high-NA system is suggested. The suggested anamorphic NA system has nonisotropic magnification, x-magnification of and y-magnification of , and the mask NA shape is an ellipse due to the nonisotropic magnification distribution. Anamorphic NA systems have a nonconventional shadow effect due to nonisotropic incident angle distribution and magnification. These nonisotropic characteristics lead to the reduction of asymmetric shadow distribution and a reduction of horizontal–vertical bias. As a result, anamorphic NA systems can achieve balanced patterning results regardless of pattern direction and incident direction.
© 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)
In-Seon Kim, In-Seon Kim, Guk-Jin Kim, Guk-Jin Kim, Michael Yeung, Michael Yeung, Eytan Barouch, Eytan Barouch, Seong-Wook Kim, Seong-Wook Kim, Hye-Keun Oh, Hye-Keun Oh, } "Anisotropic shadow effects with various pattern directions in an anamorphic high numerical aperture system," Journal of Micro/Nanolithography, MEMS, and MOEMS 15(3), 033504 (1 August 2016). https://doi.org/10.1117/1.JMM.15.3.033504 . Submission:
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