Simultaneous determination of optical constants, thickness, and surface roughness of thin film from spectrophotometric measurements

Abstract

A model taking into consideration the refractive index inhomogeneity and surface roughness of a film was proposed for the simultaneous determination of the optical constants, thickness, and surface roughness of a single-layer thin film from spectrophotometric measurements. In the model, the rough surface was treated as an effective absorbing layer. The model was applied to determine simultaneously the parameters of single-layer MgF(2) thin films deposited on fused silica substrates by the oblique-angle deposition technique. The film thicknesses and rms surface roughnesses extracted from spectrophotometric measurements with the proposed model were in good agreement with the values measured by a spectroscopic ellipsometer and an atomic force microscope, respectively.