Characterization of EUV periodic multilayers

13 pages; International audience; Nanometric Co/Mg, Co/Mg/B4C, Al/SiC and Al/Mo/SiC periodic multilayers deposited by magnetron sputtering are studied in order to correlate their optical performances in the extreme ultraviolet (EUV) range to their structural quality. To that purpose, our recently developed methodology based on high resolution x-ray emission spectroscopy (XES) and x-ray and EUV reflectometry is now extended to nuclear magnetic resonance (NMR) spectroscopy and time-of-flight secondary ions mass spectrometry (ToF-SIMS). The analysis of the Co Lalpha,beta and Mg Kbeta emission spectra shows that the Co and Mg atoms within the multilayers are in a chemical state equivalent to that of the atoms in the pure Co and Mg references respectively. But NMR spectra give evidence for a reaction between Co atoms and B and/or C atoms from B4C. The Al and Si Kbeta emission spectra do not reveal the formation of an interfacial compound in Al/SiC and Al/Mo/SiC. Only the roughness limits the optical quality of Al/SiC. The comparative analysis of the ToF-SIMS spectra of Al/SiC and Al/Mo/SiC indicates that the structural quality is enhanced when Mo is introduced within the stack.