Achievement of Low Stress in Mo/Si Multilayer Mirrors

Abstract

The feasibility of low stress Mo/Si multilayers was studied in an attempt to fabricate flat semi-transparent multilayer mirrors as beam splitters near 13 nm wavelength. Stress in periodic multilayer structures is independent of the number of bilayer pairs, and depends strongly on the multilayer period, and the ratio of the layer thicknesses. Transition of stress from compressive to tensile state is observed in Mo/Si multilayers as Γ, the ratio of the Mo layer thickness to the multilayer period, increases. Low stress Mo/Si multilayers have been achieved, and achievement of Mo/Si beam splitters is demonstrated.