X-measuring ellipsometer (XME): a novel ellipsometric technique to fully characterize film-substrate systems

Abstract

We discuss the X-measuring ellipsometer which measures the film-thickness exponential function of a film-substrate system: detecting two conditions on X. It works for all types of film-substrate systems: negative, zero, and positive. Only the transparent zero film-substrate system is discussed in detail. We present more than one ellipsometric configuration to implement the technique. We also present the inversion procedure to obtain the optical constants of the film and the substrate, in addition to the film thickness. Closed-form formulas to obtain the film thickness; the film thickness and its multiplicity; or the film thickness, its multiplicity, and the film and substrate optical constants using one, two, or three measurements, respectively. The instrument is versatile, accurate, fast, and is easily automated. The measurement multiplicity as related to the film thickness, and the permissible-thickness bands and forbidden-thickness gaps are briefly presented and discussed.