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Most important requirements for the deposition of x-ray optical multilayers are a) using a stable and reproducible
deposition technique and b) to find growth conditions where the interfaces between adjacent layers are abrupt (no
interdiffusion σd) and smooth (no roughness σr). The interface width σ (σ2 = σd
2 + σr 2) becomes increasingly important
for smaller period thicknesses. Furthermore, the kinetic energies of the condensing particles on the substrate surface are
of special importance for the interface formation. The ion beam sputter deposition technique (IBSD) provides stable and
well adjustable particle energies combined with medium to high deposition rates allowing the fabrication of precise
multilayer stacks for x-ray optical applications.
We will present our newly installed large area IBSD facility with 400 x 100 mm2 linear ion sources and substrate sizes of
up to 200 mm diameter (circular) or 500 x 100 mm2 (rectangular) and its characteristics concerning thickness
homogeneity and process stability. First experimental results of metal/non-metal multilayer depositions with thickness
uniformities of 99,9% over the entire substrate area are discussed. Different material combinations (Ni/B4C, Ni/C,
Mo/Si) with period thicknesses between 2 nm and 10 nm have been fabricated and characterized by x-ray and EUV
reflectometry. Interface widths are typically in the order of 0.3 nm. For the Ni-based multilayers Cu-Kα reflectances of
R > 80 % can be obtained with period thicknesses dP greater than or equal to 2.5 nm (Ni/B4C) and dP greater than or equal to 3.0 nm (Ni/C). EUV reflectances of the
Mo/Si multilayers are as high as R = 68,0 % at λ = 13,5 nm (incidence angle α = 5 deg).
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