High performance La/B4C multilayer mirrors with barrier layers for the next generation lithography

Results on optimization and manufacturing of La/B4C multilayers are reported. Such mirrors are promising optical elements for the development of the next generation of nano-lithography at an operation wavelength of 6.7 nm. A near-normal incidence reflectivity of up to 58.6% has been measured at the BESSY-II soft x-ray reflectometer beamline. This is the highest reflectivity measured so far at this wavelength. The potential to further increase the reflectivity of the multilayers is discussed. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4774298]