TY - JOUR
AU - Yuka Esashi
AU - Michael Tanksalvala
AU - Zhe Zhang
AU - Nicholas Jenkins
AU - Henry Kapteyn
AU - Margaret Murnane
AB - The influence of surface and interface roughness on X-ray and extreme ultraviolet (EUV) reflectometry is becoming increasingly important as layer thicknesses decrease to a few nanometers in next-generation nanodevices and multilayer optics. Here we simulate two different approaches for numerically modeling roughness, the Nevot-Croce factor and the graded-interface method, in the Parratt formalism of calculating the complex reflectance of multilayer systems. The simulations were carried out at wavelengths relevant to widely used metrology techniques, including 0.154 nm for X-ray reflectometry and 13.5 nm for EUV lithography. A large discrepancy is observed between the two approaches in several situations: when the roughness is large with respect to the wavelength, for interfaces with large changes in refractive index across the boundary, as well as around reflectance peaks due to interference effects. Caution is thus required when using either approach to model roughness in these situations. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.
BT - OSA Continuum
DA - 2021-05
DO - 10.1364/osac.422924
IS - 5
N2 - The influence of surface and interface roughness on X-ray and extreme ultraviolet (EUV) reflectometry is becoming increasingly important as layer thicknesses decrease to a few nanometers in next-generation nanodevices and multilayer optics. Here we simulate two different approaches for numerically modeling roughness, the Nevot-Croce factor and the graded-interface method, in the Parratt formalism of calculating the complex reflectance of multilayer systems. The simulations were carried out at wavelengths relevant to widely used metrology techniques, including 0.154 nm for X-ray reflectometry and 13.5 nm for EUV lithography. A large discrepancy is observed between the two approaches in several situations: when the roughness is large with respect to the wavelength, for interfaces with large changes in refractive index across the boundary, as well as around reflectance peaks due to interference effects. Caution is thus required when using either approach to model roughness in these situations. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.
PB - The Optical Society
PY - 2021
EP - 1497
T2 - OSA Continuum
TI - Influence of surface and interface roughness on X-ray and extreme ultraviolet reflectance: A comparative numerical study
VL - 4
SN - 2578-7519
ER -