Non-normalized Mueller ellipsometry is better than normalized Mueller ellipsometry

Poul-Erik Hansen; Thomas Siefke; Astrid Tranum Rømer

doi:10.1117/12.2673252

10 August 2023 Non-normalized Mueller ellipsometry is better than normalized Mueller ellipsometry

Poul-Erik Hansen, Thomas Siefke, Astrid Tranum Rømer

Proceedings Volume 12619, Modeling Aspects in Optical Metrology IX; 1261906 (2023) https://doi.org/10.1117/12.2673252
Event: SPIE Optical Metrology, 2023, Munich, Germany

Abstract

Mueller ellipsometry is one of the most sensitive techniques for accurate measurements of sub-wavelength structures and is an attractive upgrade compared to simple intensity-based scatterometry. In Non-normalized Mueller ellipsometry, all 16 elements of the Mueller matrix are measured. However, most Mueller matrix ellipsometers provide data which are normalized to the first Mueller matrix. In this work, we demonstrate that knowledge about the first Mueller matrix element, which can be acquired from a scatterometry measurement, greatly enhances the measurement accuracy. We demonstrate the advantage of Non-normalized Mueller ellipsometry over normalized Mueller ellipsometry by comparing the results obtained by the the two methods on a set of silicon line gratings with a pitch of 589 nm. The experimental data was acquired at fixed angle of incidence of 70 degrees using wavelengths from 200 to 850 nm. The data analysis involves inverse problem solving, which requires an optical model describing the system. Here we use the Rigorous Coupled Wave Analysis (RCWA) method to simulate the optical response from the grating structures. The combination of Non-normalized Mueller ellipsometry with advanced inverse modelling from rigorous simulations of the optical model structure enables high accuracy measurements of nanostructures. Notably, this approach allows for accurate measurements of grating structures in which the slimness or shape of the grooves make them inadequate for AFM measurements.

Conference Presentation

Citation Download Citation

Poul-Erik Hansen, Thomas Siefke, and Astrid Tranum Rømer "Non-normalized Mueller ellipsometry is better than normalized Mueller ellipsometry", Proc. SPIE 12619, Modeling Aspects in Optical Metrology IX, 1261906 (10 August 2023); https://doi.org/10.1117/12.2673252

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