Paul van Gerven
9 February

Imec successfully printed a 20nm pitch line/space pattern using high-NA interference lithography. As no high-NA EUV scanners are available yet, experiments such as these help to develop the lithographic materials required for the successor of ‘regular’ 0.33 NA EUV lithography. ASML’s first high-NA tool, called the EXE:5000, is slated for introduction in 2022.

Moving on to high-NA EUV lithography isn’t simply a matter of installing a new tool. New insights into the interaction of photons with photoresists are necessary. Imec is studying these dynamics in its Attolab research facility, set up together with the US high-tech laser company KMLabs. This involves emulating high-NA exposures by generating finely detailed interference patterns using mirrors and pulsed lasers, while simultaneously running time-resolved spectroscopy experiments.

Schematic representation of the Attolab’s setup for high-NA EUV interference lithography. Credit: Imec

The Attolab is the first to print 20nm pitch patterns using 13.5 nm EUV light under high-NA conditions. It expects to eventually go down to 8nm pitch. Apart from getting a head start on chip manufacturing using high-NA scanners, the research also provides additional insights into 0.33 NA lithography, which is already being pushed to its ultimate single-exposure resolution limits. Other materials research areas, such as in development of next-generation logic, memory and quantum devices, can also benefit from the analytic capabilities in Leuven.

Next up is a move to larger substrates. Currently, the Attolab is installing a 300mm-wafer-compatible EUV interference lithography beamline.