Development of multilayer mirrors for use in the wavelength region of 4 nm

Ishino, Masahiko; Yoda, Osamu*; Koike, Masato

We have developed soft X-ray multilayer mirrors for use around the wavelength region of 4 nm including the K-absorption edge of carbon (). We have chosen CoO and Cr as the final candidate materials for absorber layers, and SiO and Sc for the spacer materials as the result of theoretical invitation. CoO/SiO, CoO/Sc and Cr/Sc multilayer mirrors have been fabricated by means of an ion beam sputtering (IBS) method. As the result of structure evaluations with X-ray diffraction measurement, we have found that the fabricated CoO/Sc and Cr/Sc multilayer mirrors have stable structures. Soft X-ray reflectivity measurements for fabricated multilayer mirrors are carried out in the wavelength region of 4 nm with a synchrotron radiation source. We have found that the Cr/Sc multilayer mirror has a high soft X-ray reflectivity. However, soft X-ray reflectivities below the absorption edge of carbon are reduced. The analyses obtained by EPMA and SIMS suggested that this phenomenon was attributed to contamination of carbon.