Interface roughness evolution in sputtered WSi2∕Si multilayers

Abstract

We report on the growth of WSi 2 and Si amorphous thin films by dc magnetron sputtering. In situ synchrotron x-ray scattering with high temporal resolution has been employed to probe the surface and interface roughness during film deposition. It is found that the WSi 2 / Si multilayer surface alternately roughens and smoothes during deposition; while the Si layer roughness monotonically, the WSi 2 layer is observed to smooth out when deposited on an initially rough surface. Subsequent deposition of the next layer effectively freezes in the surface morphology of the previous layer in each case. Energetic neutrals and ions assisting the growth may play a role in inducing this pronounced alternating pattern in the roughness.

Multilayer Laue Lens: A Path Toward One Nanometer X-Ray Focusing

“…The low buildup stress avoids the occurrence of delamination. In-situ X-ray reflectivity study also revealed that the noticeably rough Si layer can be sharpened by the WSi 2 layer [25], leading to interfaces with very small roughness. The speed of sputtering is another concern.…”

A compact UHV deposition system for in situ study of ultrathin films via hard x-ray scattering and spectroscopy

“…In particular, in situ x-ray reflectivity was often used to follow the evolution of the film morphology ͑roughness, thickness͒ in real time during growth. [9][10][11][12][13] In order to perform reflectivity as well as other x-ray scattering experiments, several portable deposition systems have been developed. [13][14][15] They usually feature a compact design with large x-ray windows which allows to perform different x-ray scattering experiments such as reflectivity and small angle scattering.…”

Small d-spacing WSi2/Si multilayers for X-ray monochromators

“…Each multilayer consists of a saturated number of bi-layers in the calculation. The values for the interface roughness were set as 0.25 and 0.35 nm for Si-on-WSi 2 and WSi 2 -on-Si, respectively, to approximate the real multilayer structure based on the reported experimental results [18] . In this study, roughness indicates the interface width of the two materials, including both the pure root-mean-square (RMS) roughness and the diffuseness.…”

“…In addition, the W/Si and W/B 4 C materials have high optical contrast, limiting their theoretical spectral resolution [17] . WSi 2 /Si has been utilized to fabricate multilayer mirrors because of its sharp interfaces [18] and good thermal stability [19] . It shows a more stable stress property, which is suitable for the fabrication of thick multilayer optics [6,20] .…”