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Measurement of complex refractive index using microellipsometry and its relevance to surface measurement using coherence scanning interferometry.

Palodhi, K*; Coupland, J M*; Leach, R K (2011) Measurement of complex refractive index using microellipsometry and its relevance to surface measurement using coherence scanning interferometry. In: 13th International Conference on Metrology and Properties of Engineering Surfaces., 12-15 April 2011, Twickenham Stadium, UK.

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Abstract

Coherence scanning interferometry (CSI) is an increasingly popular method to provide high resolution measurements of surfaces. In essence sub-nanometre axial resolution is achieved by measuring the phase of the field scattered from the surface of interest. The phase is not simply a function of surface height, however, but depends on the complex refractive index of the surface material. The phase contribution due to materials properties is small and approximately constant across the field of view for the case of homogenous surfaces. It can lead to significant measurement errors, however, when composite micro- structures of conducting and non-conducting media are examined.
This paper discusses the measurement of complex refractive index using a single-point micro-ellipsometer based on a Michelson interferometer. It shows how the optical properties of the substrate are related to the phase of the scattered components at different spatial frequencies. A whole-field implementation of the method using CSI is then discussed.

Item Type: Conference or Workshop Item (UNSPECIFIED)
Keywords: coherence scanning interferometry, surface measurement, microellipsometer, complex refractive index
Subjects: Engineering Measurements
Engineering Measurements > Dimensional
Last Modified: 02 Feb 2018 13:14
URI: http://eprintspublications.npl.co.uk/id/eprint/4972

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