Analysis of residual stress in W/B₄C multilayer

The microstructure and residual stress are investigated in periodic W/B₄C x-ray multilayers (MLs) as a function of the number of layer pairs (N) varying from 20 to 400 at a fixed periodicity, d ∼ 1.9 nm. The microstructure is analyzed using the x-ray reflectivity (XRR) and rocking scan method whereas stress is analyzed using both curvature measurement method by Fizeau interferometer and grazing incident x-ray diffraction (GIXRD) using synchrotron. The successive order Bragg peaks indicates good quality of ML structure in terms of interface roughness. As N increases, roughness of B₄C and W varies in the range of 0.15-0.22 nm and 0.26-0.44 nm, respectively. The residual stress of the ML film and W layers are compressive in nature. The compressive residual stress of W/B₄C multilayer film and the W layers decreases as the number of layer pair increases, and discussed. (author)