Multiparameter characterization of subnanometre Cr/Sc multilayers based on complementary measurements

Area of Science:

• Materials Science
• Optics
• Surface Science

Background:

• Chromium/Scandium (Cr/Sc) multilayer systems are essential for fabricating near-normal incidence mirrors.
• These mirrors are particularly important for applications within the water window spectral range.

Purpose of the Study:

• To demonstrate the detailed characterization of Cr/Sc multilayer systems with sub-nanometer layer thicknesses.
• To validate advanced analytical techniques for precise multilayer parameter determination.

Main Methods:

• Utilized extreme ultraviolet (EUV) and X-ray reflectance measurements.
• Employed resonant EUV reflectance across the Scandium (Sc) L edge.
• Incorporated X-ray standing wave fluorescence and diffuse scattering measurements.
• Applied particle-swarm optimization and Markov chain Monte Carlo (MCMC) methods for model parameter determination.

Main Results:

• Achieved detailed characterization of Cr/Sc multilayer systems comprising 400 bilayers with individual layer thicknesses below 1 nm.
• Successfully determined multilayer model parameters, including interface roughness.
• Validated the accuracy and reliability of the combined analytical techniques.

Conclusions:

• Detailed characterization of advanced Cr/Sc multilayer mirrors is feasible using a combination of sophisticated analytical methods.
• The employed techniques provide precise insights into the structure and properties of thin multilayer systems.
• This work advances the understanding and fabrication of high-performance optical components for specific spectral ranges.