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Some aspects on the uncertainty calculation in Mueller ellipsometry
Optics Express
|April 1, 2020
Summary
Accurate uncertainty estimation in spectroscopic Mueller ellipsometry is crucial. This study introduces a novel merit function that correctly accounts for depolarization, improving measurement uncertainty calculations for thin films like SiO2 on Si.
Area of Science:
- Materials Science
- Optical Metrology
- Spectroscopy
Background:
- Spectroscopic Mueller ellipsometry (SME) is a powerful technique for characterizing thin films.
- Accurate uncertainty estimation is vital for reliable metrological results in SME.
- Current methods often fail to correctly estimate uncertainties due to improper handling of depolarization.
Purpose of the Study:
- To investigate the metrological aspects of SME, specifically uncertainty estimation.
- To identify the reasons for discrepancies in uncertainty calculations using conventional merit functions.
- To propose a new, improved merit function for more accurate uncertainty estimation in SME.
Main Methods:
- Utilized simulated Mueller matrices to analyze uncertainty estimation.
- Investigated the impact of sample-induced and measured depolarization on parameter fitting.
- Developed and proposed a novel merit function that incorporates measured depolarization as a weighting parameter.
- Introduced an extension to include measurement noise in the merit function.
Main Results:
- Demonstrated that commonly used merit functions yield incorrect uncertainties for parameters like SiO2 layer thickness on Si.
- Identified non-optimal treatment of depolarization as the primary cause of these discrepancies.
- The proposed merit function, which weights depolarization, provides more accurate uncertainty estimations.
- The extended merit function enables reliable statistical uncertainty calculations.
Conclusions:
- The novel merit function offers a computationally inexpensive and effective solution for accurate uncertainty estimation in SME.
- Properly accounting for depolarization is essential for reliable metrological results in spectroscopic Mueller ellipsometry.
- The proposed method enhances the reliability of thin film characterization using SME without significant computational overhead.
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