Lecture
Van Marum Colloquium: Perfect thin films and interface engineering for EUV lithography
- Prof. Marcelo Ackermann (ARCNL)
- Date
- Friday 18 September 2026
- Time
- Location
-
Gorlaeus Building
Einsteinweg 55
2333 CC Leiden - Room
- CE.0.18
Abstract
ASML’s EUV scanner has taken the world by storm – EUV is at the core of the newest AI chips and of geopolitical rivalries. The chips made with EUV outperform their DUV equivalents, and all chips made on newer nodes require several steps of EUV for their smallest features. The short wavelength of the EUV light – 13.5nm – is the key to printing such small features. But working with this wavelength is also incredibly challenging: Not only is a completely new light source required – moving from ArF and KrF excimer lasers to Sn-based laser-produced-plasma, also all optical components had to be re-invented. Traditional lenses no longer work at 13.5 nm – as glass is not transparent at that wavelength. Our universities and research centers in Amsterdam and Enschede have worked to improve to an incredible level both the EUV source, but also the EUV optics, with coatings requiring atomically perfect layers and interfaces in order to reflect the EUV light in a world where every % counts. Most importantly the sharpness of the interface between the layers is key to achieve high reflectivity. Roughness, intermixing and compound formation at these interfaces result in reflectivity losses. To improve these interfaces, metrology is needed to resolve on the atomic level, what the driving mechanisms are that lead to reflectivity loss. At the sub-nm scale, a single technique is often insufficient to fully understand the physics of intermixing: Whereas TEM and XRR can resolve the local atomic or electronic density, XPS is optimal to highlight compound formation. We demonstrate that only a combination these techniques can truly resolve the interface. Using this knowledge on the nm-scale, we optimize the multilayer using diffusion barriers to limit intermixing and low energy ion polishing to minimize roughness, resulting in record reflectivities for both 13.5nm and Soft X-ray multilayers.
Biography
Prof Ackermann is the director of ARCNL – the advanced research centre for nanolithography: A public-private research institute co-funded by the Dutch national science foundation, ASML and three major universities. It is home to over 100 researchers working on the future of EUV and advanced lithography. Prof Ackermann also still holds the chair of the XUV optics group at the MESA+ institute of University of Twente. He obtained his PhD in physics (cum laude) in 2007 at Leiden University. After that held different leading positions in industrial research for the development of X-ray, visible and IR optics for companies like cosine Research, Helbling Technik, SCHOTT Advanced Optics and ASML. In 2020 he re-joined academic research as full professor, focussing on the development of next generation X-ray and EUV optics in collaboration with industrial partners like Carl Zeiss SMT, ASML and Malvern Panalytical. He has published over 60 peer reviewed papers and holds patents in advanced optics systems ranging from space-based telescopes to medical optics and lithography.