X-Ray Reflectivity: A New Tool for Surface and Interface Roughness Analysis

• Fujii Y

  English

  Author

The Parratt formalism has been used to calculate the X-ray reflectivity in conventional XRR analysis, while the theory of Nevot-Croce has
usually been used to account for the influence of roughness. On the other hand, the calculated results often exhibit strange behavior, including a
heightened presence of interference effects in close proximity to rough surfaces. Because the model was oversimplified, the equation did not
take into consideration diffuse scattering at the rough surface, which led to the unexpected result. An significant disparity was seen between the
TEM and conventional XRR formulas for interface roughness, which resulted in the deduction of surface features unrelated to the issue at hand.
Our novel and improved formalism allowed us to circumvent this limitation. It is necessary to modify the transmission coefficient parameters in
order for the output from the revised formalism to match that of the TEM. By comparing data on surface roughness measured by atomic force
microscopy (AFM) on the same material, we hoped to identify a more accurate XRR formalism. Remember that the AFM and sectioned TEM
surface and interface roughness values are only for reference within the observed area. According to the results, the effective roughness
measurement of XRR may rely on the angle of incidence. After that, we proved that the effective roughness changed depending on the angle of
X-ray incidence. The new and improved XRR formalism accounted for the size of the coherent X-rays probing area, surface and interface
roughness were measured more precisely, and the roughness correlation function and lateral correlation length were calculated. This research
presents a new XRR formalism that incorporates diffuse scattering and effective roughness. The theory is used to generate a precise assessment
of the X-ray reflectivity from a surface with many layers of thin film materials.

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