Spectroscopic Ellipsometry. Empirical Dielectric Function for Amorphous Materials and Fluctuated Thickness Model.

Abstract

An empirical dielectric function (EDF) and a fluctuated thickness model (FTM) for SE analysis are proposed. EDF satisfies the Kramers-Kronig relations and is applicable to various amorphous materials in the wide spectral range. Several dielectric functions proposed so far are compared together with EDF by applying them to the established table values of of a-Si and a-Si3N4. EDF is used to characterize Si rich nitride (SiRN) films for deep UV lithography as an example. FTM is applied to the characterization of SIMOX (Separation by Implanted Oxygen) with nm thick top Si layer and is found to be much better than introducing an interface roughness layer whose dielectric constants are expressed by an effective medium approximation (EMA). By introducing FTM to the analysis of SIMOX, thickness dependence of dielectric constants in the top Si layers thinner than 5 nm has become able to be detected.