EUV lithography (EUVL) for a limit resolution below 8 nm requires the numerical aperture (NA) of the projection optics to be larger than 0.50. For such a high-NA optics a configuration of 4x magnification, full field size of 26 x 33 mm² and 6’’ mask is not feasible anymore. The increased chief ray angle and higher NA at reticle lead to non-acceptable mask shadowing effects. These shadowing effects can only be controlled by increasing the magnification, hence reducing the system productivity or demanding larger mask sizes. We demonstrate that the best compromise in imaging, productivity and field split is a so-called anamorphic magnification and a half field of 26 x 16.5 mm² but utilizing existing 6’’ mask infrastructure. We discuss the optical solutions for such anamorphic high-NA EUVL.

Date Published: 4 September 2015
PDF: 9 pages
Proc. SPIE 9661, 31st European Mask and Lithography Conference, 96610T (4 September 2015); doi: 10.1117/12.2196393

Published in SPIE Proceedings Vol. 9661:
31st European Mask and Lithography Conference
Uwe F.W. Behringer; Jo Finders, Editor(s)