Structural properties of sub nanometer thick layers to enhance EUV multilayer mirror reflectance

Theoretically a transition metal (TM) interlayer of sub nanometer thickness on top of Mo can improve the dielectric distribution in Mo/Si multilayer structures such, that the EUV reflection at 13.5 nm is increased. To learn the actual effect, the structure and optical properties of B4C/Mo/TM/Si multilayer systems were studied. X-ray reflectometry, AR-XPS and EXAFS at the Mo and transition metal K-edge were used to investigate average interface roughness of the multilayer period and morphology of the transition metal layer and Mo/TM interface. Furthermore EXAFS was used to study the effect of a thin interlayer upon the Mo-silicide formation, suggesting enhanced optical contrast.