EUV optics

For beam guiding and beamforming of EUV and X-ray radiation, special beam manipulation systems have to be used since no transparent materials exist for this spectral range. Moreover, all materials exhibit high absorption at these wavelengths. Therefore, special multilayer mirrors have to be used for the beam guidance and beamforming of EUV and X-ray radiation, which must meet the stringent requirements in the coating of the monolayer area. Fraunhofer IOF designs, develops and optimizes highly reflective multi-layer mirrors for applications in the EUV and soft X-ray field. The prerequisites for this are a basic understanding of layer growth processes, the use of new design approaches to minimize roughness and interdiffusion at the interfacial surfaces, and the further development of various coating technologies. Currently EUV mirrors can be manufactured up to a diameter of 660 mm and with a reflection of almost 70%.

Fraunhofer IWS uses processes of magnetron and ion beam sputter deposition as well as pulse laser deposition to deposit nanometer single and multi-layers for EUV and X-ray optics. The layer systems meet the highest requirements with regard to layer thickness accuracy, roughness, chemical purity, lateral homogeneity and reproducibility.

When plasma-irradiated radiation sources are integrated into optical systems, measures are required to protect optical elements against the debris of the source (fast ions, electrode material) and to guide the beam in the vacuum. Fraunhofer ILT is working on adapting debris mitigation systems, while also taking into account the plasma properties and the boundary conditions through the customer’s optical system, as well as on designing collector optics optimally.