Geometrical properties of microstructures by Mirau interferometric objective microscope

M. Juárez; R. Rodríguez-Vera; J. Rayas

doi:10.1117/12.903255

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2 November 2011 Geometrical properties of microstructures by Mirau interferometric objective microscope

M. Juárez; R. Rodríguez-Vera; J. Rayas

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Proceedings Volume 8011, 22nd Congress of the International Commission for Optics: Light for the Development of the World; 80117N (2011) https://doi.org/10.1117/12.903255
Event: International Commission for Optics (ICO 22), 2011, Puebla, Mexico

Abstract

This paper describes a micro-topography measurement system using a Mirau interferometric microscope objective. Such system is a non-invasive, full-field, economical, and compact. The interferometer device consists of a beam splitter that permits send a portion of the light to the sample surface and other part to a reference surface. Reflected light from these surfaces are combined to form interference fringes which are captured by a CCD camera. For each local point on the surface target, there is a distance from the Mirau microscope objective lens. Then, each fringe provides the locus of points of equal phase in the interferogram image. Contour lines corresponding to the surface target topography are extracted from the interferograms using digital image processing. Phase-stepping technique have been used in order to have a phase map which is unwrapped and mapped to a full-field microscopic data topography of the surface target. Object target is mounted on computer controlled stage with capability of linear movements of the order of nanometers. With this, the phase-stepping technique was done. For calibrating, a step-in-shape made of thin film on a glass substrate is built up. The obtained depth resolution is of 15 ± 4 nm, employing the interferometric system. Experimental results were compared with an Atomic Force Microscope, (AFM) giving an overall error of 17 nm on a 33μm × 45μm field of view. An application for integrated optics on-chip quality control is suggested.

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M. Juárez, R. Rodríguez-Vera, and J. Rayas "Geometrical properties of microstructures by Mirau interferometric objective microscope", Proc. SPIE 8011, 22nd Congress of the International Commission for Optics: Light for the Development of the World, 80117N (2 November 2011); https://doi.org/10.1117/12.903255