Full Field Imaging Ellipsometry (FFIE) Platform Using CCD Camera and Advanced Software for Simultaneous Spots' Sensing and Measurement

Full Field Imaging Ellipsometry (FFIE) Platform Using CCD Camera and Advanced Software for Simultaneous Spots' Sensing and Measurement

Avi Karsenty (Lev Academic Center, Faculty of Engineering, Department of Applied Physics/Electro-Optics Engineering, Jerusalem, Israel), Shmuel Feldman (Lev Academic Center, Faculty of Engineering, Department of Applied Physics/Electro-Optics Engineering, Jerusalem, Israel), Zvi Veig (Lev Academic Center, Faculty of Engineering, Department of Applied Physics/Electro-Optics Engineering, Jerusalem, Israel) and Yoel Arieli (Lev Academic Center, Faculty of Engineering, Department of Applied Physics/Electro-Optics Engineering, Jerusalem, Israel)
DOI: 10.4018/IJMTIE.2017010104
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Abstract

This article describes a new approach for performing full field imaging ellipsometry. In this new technique, the objective lens of a high numerical aperture microscope is used to illuminate the surface of a 2D object. The light reflected from each point of the surface is gathered by the same lens and projected onto a 2D CCD detectors array; thus, enabling the measurement of numerous surface points simultaneously. Using this simple method, areas of up to 0.9 cm2 can be measured with high accuracy. Since the nanotechnology domain is rapidly growing, such a technique can bring benefits to the scientific community, facing the need to analyze large surfaces of thin films.
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1. Introduction

Ellipsometry is a well-known Non-Destructive Evaluation (NDE) optical method for determining film thickness and optical properties. It measures the change in the state of polarization of light reflected from films’ surface. Fast ellipsometry methods, single or multi-wavelengths, have been adopted for monitoring film growth in situ, allowing for the precise control of film deposition processes (Muller, 2005). With time, several parameters have been separately and largely investigated, such as in-situ measurements of materials complex permittivity using reflection ellipsometry (Sagnard, 2005), and arbitrary refractive index profile of composite thin films (Ho, 1990).

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. In the last two decades, new generations of ellipsometers came up with additional specifications and techniques, such as spectroscopic ellipsometry (Jung, 2008), methods of calibration (Asinovski, 2008), stroboscopic illumination technique (Han, 2006), and customization (Acurion, 2004). Even apertureless optical near-field scanning microscope system was created by combining a commercially available atomic force microscope and an Ellipsometer (Karageorgiev, 2001). Moreover, ellipsometry became suitable for optical sensing (Arwin, 2001) and film sensing applications (Sinibaldi, 2013).

A big leap ahead was stepped forward by developing new techniques of imaging ellipsometry (IE), e.g. combined microscopy and Thin Film Characterization (TFC), which overcomes the limits of classical ellipsometry, the spatial resolution. Besides the determination of film thickness and optical properties, one receives high contrast ellipsometric images from the surface with highest resolution. Small samples, structured materials or inhomogeneous surfaces, which are beyond the capabilities of other ellipsometric tools, are now visible with IE and this opens new doors to a better understanding of today’s advanced thin film and biological applications. However, the known IE are still complicated or limited in their performance. For example, the moving ellipsometry system based on Polarizer Compensator Surface Analyzer (PCSA) components, and enabling a null ellipsometry technique, is not strong enough to measure large surfaces.

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