Optical method for determining the power spectral density function of randomly rough surfaces by simultaneous processing of spectroscopic reflectometry, variable-angle spectroscopic ellipsometry and angle-resolved scattering data
| Authors | |
|---|---|
| Year of publication | 2023 |
| Type | Article in Periodical |
| Magazine / Source | Optik |
| MU Faculty or unit | |
| Citation | |
| Web | https://doi.org/10.1016/j.ijleo.2023.170775 |
| Doi | http://dx.doi.org/10.1016/j.ijleo.2023.170775 |
| Keywords | Roughness; Angle-resolved scattering; Ellipsometry; Power spectral density function; Rayleigh-Rice theory; Scalar diffraction theory |
| Description | Two samples of silicon-single crystal substrates with randomly rough surfaces covered by native oxide layers are investigated by means of angle-resolved scattering, spectroscopic reflectometry and variable-angle spectroscopic ellipsometry. For each sample, the experimental optical data are processed simultaneously to determine the power spectral density functions, which are modeled by exponentials of quadratic splines. The thicknesses of native oxide layers are also determined. The influence of roughness on the reflectance and ellipsometry is described by the combination of the scalar diffraction theory, which is used for the part of roughness with low spatial frequencies, and the Rayleigh-Rice theory, which is used for the part of roughness with high and moderate spatial frequencies. The separation of the roughness into the parts with low and high/moderate spatial frequencies is performed using a bound dependent on the wavelength of the incident light. The PSDFs determined by the optical method are compared with the PSDFs determined by processing the AFM scans. |
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