page_title: Extreme ultraviolet lithography
section_title: EUV-specific optical issues
hierarchical_section_title: Extreme ultraviolet lithography / EUV-specific optical issues
caption_attribution_description: The 28 nm pitch images projected from different source points in the EUV pupil are different due to reflective asymmetry, resulting in both contrast and position differences. Left: 47% radius; center: 66% radius; right: 74% radius. Ref.: J. Finders et al., Proc. SPIE 9776, 97761P (2016).
context_page_description: Extreme ultraviolet lithography is a lithography technology using a range of extreme ultraviolet wavelengths, roughly spanning a 2% FWHM bandwidth about 13.5 nm.
  While EUV technology is available for mass production, 53 machines worldwide capable of producing wafers using the technique were delivered since Q1 2018, while 201 immersion lithography systems were delivered during the same period. Issues that make EUV adoption difficult are tool costs, tool uptime and stochastic phenomena. The latest NXE:3400 tools have been equipped with lower pupil fill capability for better imaging, but this leads to lower productivity due to limited use of the exposure field.
caption: Image asymmetry due to multiple illumination source points. Since the mask illuminations from different source points are at different angles, the different points actually produce different images. From left to right, the represented source points are located further away from the center. The line pitch is 28 nm.
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