Nikolai N. Salashchenko

New modification of X-ray standing waves above the surface of layered substrates under total external reflection conditions for structural characterization of organic layers

Abstract Information about the structure of organic monolayers of fatty acid salts and phospholipids deposited by the Langmuir-Blodgett technique on layered substrates has been obtained for the first time with the help of amplitude-modulated X-ray standing waves formed under total external reflection conditions. The detailed E field intensity distribution as well as the advantages of such a new modification of X-ray standing waves are discussed.

Application of point diffraction interferometry for middle spatial frequency roughness detection

The possibilities of applying the point diffraction interferometry (PDI) method for the detection of the middle spatial frequency roughness of superpolished optical surfaces are analyzed. The point source used in the experiment is based on a single mode optical fiber with the subwavelength exit aperture size, which is about 0.25 μm. In a numerical aperture of 0.01 the reference wave root-mean-square deformation is less than 0.005 nm. It is theoretically shown that the possible diffraction-limited lateral resolution of PDI while measuring a spherical substrate of 100 mm curvature radius is about 8 μm. The experiment demonstrated the possibility of obtaining roughness spectra in the range 0.001-0.05u2009u2009μm(-1). The surface map obtained by PDI, and the roughness spectra obtained by both the PDI and atomic-force microscopy methods are shown.

High-reflection Mo/Be/Si multilayers for EUV lithography

The effect of Be layers on the reflection coefficients of Mo/Be/Si multilayer mirrors in the extreme ultraviolet (EUV) region is reported. Samples were studied using laboratory and synchrotron based reflectometry, and high-resolution transmission electron microscopy. The samples under study have reflection coefficients above 71% at 13.5xa0nm and more than 72% at 12.9xa0nm in a near normal incidence mode. Calculations show that by optimizing the thickness of the Be layer it should be possible to increase the reflection coefficient by another 0.5-1%. These results are of considerable interest for EUV lithography.