Spectroscopic ellipsometry of thin copper films on glass substrates

The complex reflectance ratio, ρ= R p / R s , for p- and s-polarized lights of copper island films with the mean mass thickness d w of 4 to 16 nm on glass substrates was measured in the visible region by means of in-situ ellipsometry. The observed wavelength dependence of ρ was interpreted with the effective anisotropic continuous film model. The clear resonance peak of plasma oscillation in ε x ′′ was observed at E ≃1.8 eV, which corresponded to the mean distance between the particles of 7.5 nm in the film of d w =4 nm. The estimated particle radius r was smaller by a factor of 10 -1 or 10 -2 than the island size directly observed by means of a scanning electron microscope.