Optical scattering from oxidized metals. 2: Model verification for oxidized copper.
A model for the calculation of diffuse reflectance spectra for oxidized metals is applied to thermally oxidized copper films and compared with experiments. The model calculations reproduce the spectral structure observed in the experiments. It is demonstrated that the air-oxide interface roughness dominates the scattering for wavelengths shorter than the absorption threshold of the oxide, and the oxide-metal interface roughness dominates for longer wavelengths. Using the model for fitting calculations the rms roughness values for the two interfaces are determined independently. The roughness values agree with the results from high accuracy stylus profiling of the oxide front surface as well as stylus profiling and total integrated scattering of He-Ne light from the bare metal surface, obtained after etching away the oxide. The good overall agreement between the calculated and experimental diffuse reflectance spectra, as well as the rms roughness values determined with different techniques, confirms the applicability of the model.
Bergkvist
M
M
Roos
A
A
Ribbing
C G
CG
Bennett
J M
JM
Mattsson
L
L