Imaging ellipsometry: quantitative analysis



Imaging ellipsometry (IE) combines spatial resolution of optical microscopy with thin-film measurement capabilities of ellipsometry. It has gained significant interest in recent years and is been used for a wide range of applications from biotechnology to semiconductor metrology. Traditionally, IE is used either as a qualitative technique – not unlike polarized microscopy or Surface Plasmon Resonance (SPR) – with “ellipsometry images” showing surface topology variation, or as a quasi-quantitative technique where the change in “ellipsometry images” is used to deduce the change in film thickness. In this paper we give a brief critical review of different measurement systems configurations from the point of view of their fitness to quantitative IE measurement. We discuss the methods of calibration and correction that enable to achieve a truly quantitative IE measurement. We show that a fast and reliable quantitative IE can be practically implemented. It is consistent and can be used in lieu of a classical single point ellipsometry in many applications. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)