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Proceedings Paper

Comparison of different film thickness evaluation algorithms applicable to spectrometric interrogation systems
Author(s): Florian Hirth; Ana Pérez Grassi; Daniel G. Dorigo; Alexander W. Koch
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Paper Abstract

There are various methods for film thickness measurement. This paper aims at thin film measurement methods which work with wavelength-dependent sensor signals, no matter how the signal was captured. These measurement systems are called Thin Film Reflectometers (TFR). The resolution of thin film reflection measurement is limited by the spectral resolution of the detection system, the spectral wavelength range and the analyzing algorithm. Analytical theory of four different algorithms for thin film measurement is described and algorithms are compared via numerical simulations. Most of these algorithms can be found both in the literature and in different software-libraries (e.g. MATLAB, LabVIEW...) To compare different algorithms, the reflected light intensities of a thin film have been simulated for an exemplary thin glass film and a common off-the-shelf-spectrometer, a broadband visible light source and characteristic noise levels. The same data was fed for four selected algorithms in order to compare the results. To characterize algorithms in resolution, range and accuracy, the standard deviation of the output data has been computed for different spectral windows and resolutions. As a result we can provide a concise recommendation for appropriate use of the presented TFR algorithms.

Paper Details

Date Published: 2 August 2010
PDF: 7 pages
Proc. SPIE 7790, Interferometry XV: Techniques and Analysis, 77900V (2 August 2010); doi: 10.1117/12.859687
Show Author Affiliations
Florian Hirth, Technische Univ. München (Germany)
Ana Pérez Grassi, Technische Univ. München (Germany)
Daniel G. Dorigo, Technische Univ. München (Germany)
Alexander W. Koch, Technische Univ. München (Germany)

Published in SPIE Proceedings Vol. 7790:
Interferometry XV: Techniques and Analysis
Catherine E. Towers; Joanna Schmit; Katherine Creath, Editor(s)

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