Abstract

Ellipsometry measurements, when limited to a single angle and wavelength, yield only two parameters, V and A. This leaves us with an underspecified condition because we have three unknowns, n, k, and d. In the determination of the properties of a growing thin film, certain cases allow us to assume that one of the unknowns is either constant or is known from independent measurements. However, making measurements at multiple angles of incidence or wavelengthsis a choice we do not have when we use a single-wavelength Rudolph Research ellipsometer installed onto a Balzers coating chamber. For in situ investigations of the optical properties of low-voltage reactive ion-plated films, we cannot assume that n and k are known and constant, which makes data processing difficult and time consuming. For realistic modeling of thin-film growth from in situ ellipsometer measurements, we have included an interface layer between the substrate and the growing film. The computer algorithm that we use to determine the optical properties of this system relies on measurements taken at different film thicknesses. The accuracy of this method is determined by computer simulation of film growth in terms of the resulting ψ and Δ values.

© 1990 Optical Society of America