Implementing 0.1 nm B4C barriers in ultrashort period 1.0 nm W/Si multilayers for increased soft x-ray reflectance

Ultrashort period 1.0 nm W/Si multilayers have potential as dispersive Bragg reflectors in high-resolution x-ray fluorescence. However, formation of WSix leads to poor optical performance. To address this, we introduce ultrathin 0.1 B4C diffusion barriers sputter-deposited W/Si, inhibiting W–Si interaction. We demonstrate that the peak reflectance at a wavelength 0.834 increased with factor 3.4 compared W/Si. Diffuse scattering measurements reveal no change interfacial roughness when applying X-ray reflectivity analysis shows substantial increase contrast between Si and W well sharper transitions layers. Chemical suggests barrier reduces through partial substitution W-silicide bonds W-carbide/boride bonds, leading an contrast. The resulting structure offers compelling alternative more established W/B4C multilayer ultrashort scale due its superior soft- hard reflectance.