While EUV technology is available for mass production, 53 machines worldwide capable of producing wafers using the technique were delivered during 2018 and 2019, while 201 immersion lithography systems were delivered during the same period. Issues that make EUV adoption difficult are tool costs (ASML's EUV scanners can cost up to US$120 Million), 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. Several fundamental issues still remain.