Beyond EUV: Blue-X explores sub-13.5nm lithography

For decades, semiconductor lithography has evolved according to a pattern: Engineers squeeze as much resolution as possible from a given wavelength before leaping to a shorter one. To improve resolution without changing wavelength, chipmakers have traditionally relied on two levers: increasing the numerical aperture (NA) of the optics and refining a host of process-related parameters captured in the so-called k1 factor. Of the two, increasing NA has historically delivered the biggest gains.

EUV lithography is following this trajectory as well. Within a few years, today’s 13.5nm 0.33-NA systems will be succeeded by 0.55-NA EUV tools, better known as high-NA tools. ASML and its optics partner Zeiss have also completed a design pushing the NA to 0.75, although a decision about taking these hyper-NA systems into production hasn’t yet been made.