High-NA EUV imaging: challenges and outlook

The continuation of Moore's law demands the continuous development of EUV lithography. After the NXE:3400B scanner, currently being inserted in high-volume manufacturing (HVM), the next logical step is to increase the numerical aperture (NA) of the EUV projection optics, from 0.33 to 0.55, resulting in a high-NA EUV scanner. Looking back at the history of lithography tools developed in the last decades, we can see that such an increase of NA is, in relative terms, unprecedented (0.55 = 0.33 + 67%). This significant step forward in the NA is a challenge on many fronts and requires many adaptations. In this paper you will find an overview of the key concepts that make high-NA lithography different on imaging end, how the imaging assures the continued life of Moore's law for the years to come and what are potential mask-related developments that would contribute to high-NA's success.