Development of High-Reflective W/Si-multilayer Diffraction Grating for the Analysis of Fluorine Materials

For the analysis of fluorine materials and 3d transition metals by soft-x-ray absorption spectroscopy, A new diffraction grating with multilayer coating was installed at the BL-10 beamline of the NewSUBARU synchrotron light source. The target photon energy range of this grating is from 500 eV to 1,000 eV, which includes absorption edges of fluorine and 3d transition metals. The beam intensity of BL-10 in this range was very low due to low reflectance of the diffraction grating for the usage of monochromator. In order to obtaining high reflectance, we developed wideband W/Si multilayer and this multilayer was coated on a new diffraction grating. The reflectance of this multilayer was approximately 13-times higher than that of previous Ni single layer at the fluorine absorption energy edge of 697 eV. The beam intensity at the energy of 697 eV using the new diffraction grating was over 40 times stronger than that using the previous Ni-coated diffraction grating. As the result, using the new diffraction grating, it can be observed that the high-quality absorption spectrum of EUV resist at the absorption edge of fluorine and standard materials of 3d transition metals. The results show that the W/Si multilayer coating significantly improved the performance of the grating at the target energy range.