Wavelength-by-wavelength Kramers-Kronig consistent inversion of ellipsometry data.

The wavelength-by-wavelength (point-by-point) inversion process consists of solving the ellipsometric equations for each wavelength of the considered spectrum regardless of the other points. It provides the refractive index (${n}$n) and extinction coefficient (${k}$k) of an unknown absorbing material inside a multilayer stack from ellipsometry measurements. A revision of the wavelength-by-wavelength ${n}/{k}$n/k extraction is presented to overcome its two main deficiencies, which are (i) multiple solution possibilities and (ii) lack of Kramers-Kronig consistency. In addition, from a given estimate of thickness value, the inversion process allows one to determine it more exactly.