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Ellipsometric approach for evaluation of optical parameters in thin multilayer structures
Author(s) -
Paneva A.,
Szekeres A.
Publication year - 1993
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740200405
Subject(s) - ellipsometry , layer (electronics) , substrate (aquarium) , etching (microfabrication) , optics , materials science , thin film , thin layer , range (aeronautics) , analytical chemistry (journal) , chemistry , physics , composite material , nanotechnology , oceanography , chromatography , geology
An ellipsometric approach has been proposed for the determination of the optical parameters of a transition layer existing between a substrate and a grown film. In the approach the functions tan ψ cos Δ and tan ψ sin Δ vs. top layer thickness are approximated by the appropriate polynomials. The absolute terms of the polynomials are connected with the ellipsometric angle ψ′ and Δ′ related to the substrate‐transition layer system. For finding the tan ψ cos Δ and tan ψ′ sin Δ′ vs. top layer thikness dependences it is necessary either to each gradually the top layer and to make ellipsometric measurements after each etching step or to trace ellipsometrically the growth process of the film in situ . Since the approximation does not require the complete removal of the top layer, the proposed approach is very useful for obtaining the optical parameters of a thin intermediate film in a double‐layer—substrate structure when complete removal of the top layer is impossible without damaging the layer underneath. The error introduced by the approximation is ∼0.016°, which is within the range of the standard ellipsometric accuracy for ψ and Δ.