On determining the optical properties and layer structure from spectroscopic ellipsometric data using automated artifact minimization method

• An improved artifact minimization method is presented for ellipsometry analysis.
• Numerically inverted ε1, ε2 pairs are ranked via their Kramers–Kronig consistency.
• The ε1, ε2 pair showing the least structured self consistency curve is accepted.
• Self consistency curves are compared in terms of their root mean square.
• The method is tested on simulated and experimentally measured ellipsometric data.

An ellipsometric analysis method is presented and applied to simulated and measured ellipsometric data. It is shown that the Kramers–Kronig consistency of numerically inverted dielectric curves is lost, if interference related structures are present in the inverted dielectric function. Based on this observation, the root mean square of the self consistency curve is found to be appropriate to find the Kramers–Kronig consistent dielectric function, which belongs to a physically correct layer structure. Furthermore, it is shown that the effect of restricted photon energy range, typical to real life ellipsometric measurements, can be handled by adding an integration constant and one or two Sellmeier oscillators, whose parameters are fitted, to the Kramers–Kronig integrated dielectric function. The limitations of the method are also discussed, both on simulated and measured data.