Institute for Physics of Microstructures of the Russian Academy of Sciences, Nizhny Novgorod, Russia.
J Xray Sci Technol. 2019;27(5):857-870. doi: 10.3233/XST-190495.
Anomalously high x-ray scattering at a wavelength of 0.154 nm by super-polished substrates of fused silica, which were etched by the argon ions with the energy of 300 eV, is detected. The scattering intensity increases monotonically with increasing of the etching depth. The effect is explained by the scattering on the volume inhomogeneities with the lateral size greater than 0.5 μm of the subsurface "damaged" layer. The concentration of volume inhomogeneities increases with the increase of the fluence of argon ions, but the concentration of implanted argon atoms in the layer quickly reaches the maximum value and then begins a trend of going down. The thickness of the "damaged" layer is approximately equal to the penetration depth of the Ar atoms and can be directly determined from the x-ray specular reflection. It is shown that the presence of volume inhomogeneities of the subsurface "damaged" layer does not affect the geometric roughness of the surface. The observed effect imposes limitations on the usage of grazing incidence x-ray optics without reflective coatings and of the diffuse x-ray scattering (DXRS) method for studying the substrate roughness. A new method that potentially enables to evaluate the applicability of the DXRS method in practice is proposed.
检测到经能量为 300eV 的氩离子刻蚀的熔融石英超抛光基底在 0.154nm 波长处出现异常高的 X 射线散射。散射强度随蚀刻深度的增加而单调增加。这种效应可以通过表面下“损伤”层中具有大于 0.5μm 横向尺寸的体积不均匀性的散射来解释。体积不均匀性的浓度随氩离子通量的增加而增加，但层中注入的氩原子的浓度迅速达到最大值，然后开始下降趋势。“损伤”层的厚度约等于 Ar 原子的穿透深度，可直接从 X 射线镜面反射中确定。结果表明，亚表面“损伤”层的体积不均匀性不会影响表面的几何粗糙度。观察到的效应限制了无反射涂层的掠入射 X 射线光学和漫散射 X 射线散射（DXRS）方法在研究基底粗糙度方面的应用。提出了一种新的方法，该方法有望在实践中评估 DXRS 方法的适用性。
