Jena’s development of compact high-power EUV source wins Hugo Geiger Award

27 Mar 2023

Full EUV power at “laboratory scale” achieved by Robert Klas from Friedrich Schiller University.

Experiments with laser-like EUV light can usually only be conducted at expensive large-scale research facilities. Now Jena, Germany-based scientist Robert Klas has developed a compact extreme ultraviolet laser module that can be used to generate this special light much more cost-effectively.

Potential applications are possible in semiconductor manufacturing and microscopy. As a consequence of this breakthrough, Klas has now been awarded the Hugo Geiger Award (see below).

He developed the compact module for generating EUV light as part of his doctoral thesis. Where research facilities the size of an entire house have previously been necessary so far – so-called synchrotrons – Klas has developed an efficient method to generate EUV light in a facility the size of a lab bench.

‘One hundred times more power’

Klas’ doctoral thesis, based on cooperation between Friedrich Schiller University Jena, Helmholtz Institute Jena, and Fraunhofer Institute for Applied Optics and Precision Engineering (IAF), provides the most powerful laser-like EUV source on a laboratory scale to date, with an average power of 10 mW – one hundred times more power than the state-of-the-art in comparable systems when he began his doctorate.

In his work, Klas uses high-power ultrashort pulse fiber lasers. These are converted into EUV light using high harmonic generation. To do this, he focused the high-power laser in an inert gas. In this process, electrons are accelerated within a few 100 attoseconds.

The main challenge is to coherently superimpose the released radiation – to control it so that its so-called wavecrests in the EUV spectrum add up and can be bundled into a laser beam at the end. Through the correct choice of laser parameters as well as gas density, Klas succeeded in generating EUV radiation with laser-like parameters in a highly efficient manner.

Klas commented, “In the future, the results of my doctoral thesis are expected to drive development in many key areas such as the energy and storage efficiency of chips as well as biology and medicine.”

He has already tested the first potential applications for his novel EUV source on a laboratory scale. In exchange with other researchers, he has turned his attention to lens-less microscopy, in particular imaging in the range of a few nanometers.

“With an exposure wavelength of 13.5 nanometers, we have realized a resolution of 18 nanometers.” By comparison, conventional light microscopes typically only manage a resolution of just under 500 nm,” Klas said.

“In one experiment, we achieved a so-called field of view measuring 100 x 100 micrometers. That means we could comparatively cover the size of a soccer field within an image and find a coin in it.”

With EUV-based microscopy, colored images of a sample under investigation can be generated. In this way, researchers could look inside a cell and distinguish different elements or proportions of different substances such as carbon or lipids.

“That would be a novelty at such a high resolution,” said Klas. “With our technology, we can use this to advance biological and medical studies in the future and hopefully study different types of viruses. At some point, we also want to be able to image DNA with a diameter of about two nanometers using this method.”

There are yet further potential applications of EUV lithography in quality assurance in semiconductor manufacturing.

Hugo Geiger Award

Robert Klas has now been awarded the Hugo Geiger Award for Young Scientists for his EUV achievement. The award is granted by the Free State of Bavaria and the Fraunhofer-Gesellschaft to outstanding young researchers. The award ceremony took place on March 21 in Munich.