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	Marcus Liemen Director Operativo Phone: Mail: ml@accurion.com Dr. Peter Thiesen Senior Application Specialist Phone: +49-551-9996020 Mail: pt@accurion.com Daniela Bogner Sales Manager Phone: +49-551-9996013 Mail: db@accurion.com Linda Thieme Sales Manager Phone: +49-551-9996016 Mail: lth@accurion.com Sebastian Funke Application Specialist, 2D Materials Phone: +49-551-999600 Mail: sfu@accurion.com Dr. Christian Hoffmann Application Specialist for Biological Applications Phone: +49-551-9996021 Mail: cho@accurion.com Stephan Ferneding Director General Phone: +49-551-999600 Mail: Narayana Sharma Sales and Application Phone: +91-98450 04273 Mail: sharma@accurion.com Frank Zuo Sales and Application Phone: +86-21 5017 9099 Mail: fz@accurion.cn	Dr. Antonio Gonzalez Service and LB-Application Specialist Phone: +49-551-9996035 Mail: support@accurion.com Arash Mirhamed Product Manager Phone: (+1) 408 642 1446 Mail: am@accurion.com Holger Grube Service Engineer Phone: +49-551-9996023 Mail: support@accurion.com

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Imaging Ellipsometry - Nulling Ellipsometry

Ellipsometry is a well-known non-destructive optical method for determining film thickness and optical properties. It measures the change in the state of polarization of the light reflected off the film«s surface.

Fast ellipsometry methods, single or multi-wavelength, have been adopted for monitoring film growth in situ, allowing for the precise control of film deposition processes.

The advancement of spectroscopic ellipsometers has extended the analytical power of ellipsometry to complex multilayer coatings, where several optical parameters (refractive index, extinction coefficient, film thickness, roughness anisotropy, etc.) can be determined simultaneously.

Ellipsometry remains a macroanalysis technique, i.e., the sample size cannot be any smaller than a few millimeters. The development of imaging ellipsometry (Figure2), which combines the power of ellipsometry with microscopy, has overcome this limitation. The enhanced spatial resolution of imaging ellipsometers potentially expands ellipsometry into new areas of microanalysis, microelectronics, and bio analytics.

The unique imaging ellipsometer EP³ operates on the principle of classical null ellipsometry and real-time ellipsometric contrast imaging. The laser beam is elliptically polarized after it passes through a linear polarizer (P) and a quarter-wave plate (C). The elliptically polarized light is then reflected off the sample (S) onto an analyzer (A) and imaged onto a CCD camera through a long working distance objective.

In this PCSA configuration, the orientation of the angles of P and C is chosen in such a way that the elliptically polarized light is completely linear polarized after it is reflected off the sample. As shown in Figure3, the ellipsometric null condition is obtained when A "crossesÓ with respect to the polarization axis of the relected light, i.e., the state at which the absolute minimum of light flux is detected at the CCD camera.
The angles of P, C, and A that obtained the null condition are related to the optical properties of the sample. Reduction of the measured data with computerized optical modeling leads to a deduction of film thickness and the complex refractive indexes.