Fabrication of a two-dimensional graded periodic Mo/Si multilayer mirror using magnetron sputtering technology

Aperiodic multilayer structure and lateral gradual multilayer structure can be used to expand spectral bandwidth of multilayer polarizers. To extend application of polarization in EUV and X-ray region, two-dimensional graded multilayer structure is utilized, which is a kind of mirror with gradient period along two lateral directions and can be widely used in synchrotron radiation and polarization studies of magnetic materials. In this paper, a [Mo/Si] 25 laterally graded multilayer was deposited on a 40 mmx40 mm large silicon substrate by magnetron sputtering and it was measured by grazing incidence X-ray reflection. The d-spacing gradient along X direction, from 0.0528 nm/mm to 0.116 nm/mm, was achieved by controlling the velocity of the substrate as it passes through the flux. A shaped mask controlled the d-spacing gradient in the Y-axis perpendicular to substrate translation, from 0.12 nm/mm to 0.18 nm/mm. The d-spacing was 6.39 nm for the minimum and 15.65 nm for the maximum. This method is capable to prepare two-dimensional laterally graded multilayer mirror in EUV and X-ray regions.