Atomic masonry for EUV

The artwork behind XUV optics professor Marcelo Ackermann’s desk looks dull, but with his explanation, it comes to life. The image on plywood is based on an electron microscopy image of a molybdenum-silicon multilayer. These types of multilayer structures form the basis of mirrors that reflect extreme ultraviolet (EUV) light. In EUV lithography, ten of these mirrors condition, reduce and project a complex pattern onto a silicon wafer. Some forty XUV researchers aim to create the perfect multilayers. That is, to make sure that as much EUV light as possible reaches the wafer – and also on the right position, with almost atomic precision.

Ackermann points to the artwork, created in 2013. “At the bottom, the layers show a sharp pattern, but the higher you go, the more deviations creep in. If you make a mistake at the basis, it piles up. In the structures with about fifty layers that we’re making now, we’ve managed to get rid of all those unevennesses. If we were to recreate this artwork, it would be a perfect gray-and-white pattern.”