Exposure Tool Development Toward Advanced EUV Lithography: A Journey of 40 Years Driving Moore’s Law

In modern high-end integrated circuits (ICs) one can find billions of active elements. These ICs fuel devices like mobile phones, complex graphical engines, servers, and high-end supercomputers. This would not be possible without optical lithography, allowing for a continuous shrink in the dimensions of the individual active elements. Many technological developments over the last decades have enabled this. The continuously increasing number of elements over time is called
Moore’s law
. The resolution itself is defined by the lithography tools. Over the years, the resolution of these tools has improved from several micrometers in the early 1970s to 13 nm in state-of-the-art extreme ultraviolet (EUV) tools [
λ
= 13.5 nm, numerical aperture (NA) = 0.33] and will improve even further down to 8 nm in what are called
high-NA EUV exposure tools
(NA = 0.55). There is an outlook toward exposure tools allowing for even smaller resolutions in the next decade.