Optical constants of magnetron-sputtered boron carbide thin films from photoabsorption data in the range 30 to 770 eV

Abstract

This work discusses the experimental determination of the optical constants (refractive index) of DC-magnetron-sputtered boron carbide films in the 30-770 eV photon energy range. Transmittance measurements of three boron carbide films with thicknesses of 54.2, 79.0, and 112.5 nm were performed for this purpose. These are believed to be the first published experimental data for the refractive index of boron carbide films in the photon energy range above 160 eV and for the near-edge x-ray absorption fine structure regions around the boron K (188 eV), carbon K (284.2 eV), and oxygen K (543.1 eV) absorption edges. The density, composition, surface chemistry, and morphology of the films were also investigated using Rutherford backscattering, x-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and extreme ultraviolet reflectance measurements.

Deposition and characterization of B4C/CeO2 multilayers at 6.x nm extreme ultraviolet wavelengths

“…The d and b of B 4 C are consistent with previously reported measurements by Soufli et al 27 and Ksenzo. 29 It is also worth mentioning that optical constants of …”

“…Measured optical constants clearly demonstrate a strong nonlinear pattern near the absorption edge of boron, unlike the linear behavior of the tabulated values from CXRO database. The optical constants of B 4 C layers obtained are also fully consistent with the magnetron sputtered B 4 C thin films measured by Soufli et al, 27 Monaco et al, 28 and Ksenzov et al 29 The change of optical constants of layers in sample_02 as a function of photon energy, as derived from GI-EUVR data analysis, is plotted in Fig. 9.…”

Optical Response Near the Soft X-Ray Absorption Edges and Structural Studies of Low Optical Contrast System Using Soft X-Ray Resonant Reflectivity

“…They have also observed similar significant variation in optical constants near the boron edge with respect to Henke's tabulated value, sign reversal of f 0 1 as well as shift of absorption edge towards higher energy side. Soufli et al [98] report measured optical constants in soft X-ray region for sputter deposited B 4 C thin film and the values near the boron K-edge deviate significantly from the tabulated values by Henke et al Furthermore, they also report sign reversal for δ around the boron edge as well as shift in absorption edge towards higher energy side. The sign reversal effect of f 0 1 near B K-edge is also observed experimentally in case of boron [100].…”

“…(BN) calculated using Henke et al [61] atomic scattering database and measured values are obtained from best fit from angle dependent soft X-ray reflectivity measurements. The advantage of angle dependent X-ray reflectivity to determine optical constant is that both δ and β are obtained simultaneously and independently [98] (also see ref. [66]).…”

Wavelength selection for multilayer coatings for lithography generation beyond extreme ultraviolet

“…The solution to this problem is to use measured B and B 4 C optical constants. [16][17][18] The wavelength dependencies of the peak intensities calculated for LaN/B and LaN∕B 4 C multilayer mirrors using measured B and B 4 C and CXRO B 4 C optical constants are shown in Fig. 1.…”