An Improvement of Scanning Ellipsometer by Rotating a Polarizer and an Analyzer at a Speed Ratio of 1:3

Abstract

We propose theoretically an improved spectroscopic ellipsometer to study the optical properties of solids. In this system, the polarizer and the analyzer are rotating synchronously in the same direction at a speed ratio 1:3. The light intensity received by the detector contains six Fourier coefficients, one dc and five ac. One can independently extract the ellipsometric parameters as well as the optical constants of a sample using any of six different sets of the Fourier coefficients. A comparison among these sets is presented to find the optimal set corresponding to the minimum percent error in the calculation of the real and imaginary parts of the dielectric function. The results from the simulated spectra of the complex refractive index of c-Si, ZnSe, and GaP are presented.

Thin Film Characterization Using Rotating Polarizer Analyzer Ellipsometer with a Speed Ratio 1:3

“…It was shown that in Ref. [16] that the first two sets correspond to the minimum error compared to other sets. The parameters ψ and Δ in terms of the first set are given by a a a a a a…”

“…It is worth to mention that these valu s m of ψ and Δ were calculated using the coefficients a 1 , a 2 , and a 3 without depending on the dc offset of the signal for the clean and the noisy signals. If the dc term is considered in the calculations, the percent error in ψ and Δ would be much higher [14][15][16]. This ellipsometer in which the polarizer and the analyzer rotate in the same direction with a speed ratio 1:3 has the advantage that the results do not depend entirely on this term.…”

“…The results of bulk samples have shown high accuracy. In a recent theoretical work [16], a RPAE in which the polarizer and the analyzer are rotating synchronously in the same direction at a speed ratio 1:3 is proposed. The light intensity received by the detector contains six components, one dc and five ac, with frequencies of 2ω, 4ω, 6ω, 8ω, and 10ω, respectively.…”

“…Equations 800 nm. along with the second set corresp percent error among all sets [16] ellipsometric parameters correspond to the clean signal without considering any noise.…”

“…In this work, we examine theoretically the noise effect on the characterization of 100 nm SiO 2 thin film using the RPAE described in [16]. The structure under consideration consists of a thin SiO 2 film sandwiched between air and silicon substrate.…”