Absolute thickness measurement of silicon wafer using wavelength scanning interferometer

Young-Sik Ghim; Amit Suratkar; Angela Davies; Yun-Woo Lee

doi:10.1117/12.898354

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14 September 2011 Absolute thickness measurement of silicon wafer using wavelength scanning interferometer

Young-Sik Ghim, Amit Suratkar, Angela Davies, Yun-Woo Lee

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Proceedings Volume 8133, Dimensional Optical Metrology and Inspection for Practical Applications; 813312 (2011) https://doi.org/10.1117/12.898354
Event: SPIE Optical Engineering + Applications, 2011, San Diego, California, United States

Abstract

Wavelength scanning interferometry based on a reflectometry model is proposed for measuring the absolute thickness profile of a thin silicon wafer. A Fourier-based method of wavelength scanning interferometry is limited to thicker wafers because of a tuning range limitation of the source. As an example, the minimum thickness measurable with the conventional Fourier-based technique using a 4 nm-tunable (500 GHz) 1550 nm laser is approximately 170 μm. Our proposed method enables an extension of thickness measurements with a reduction in systematic measurement error, representing a significant advance. The so-called 'ripple-error' or 'fringe-bleed through' is much lower with a reflectometry-based analysis compared to a Fourier-based analysis. Our method was verified by measuring and testing several wafers with various thicknesses.

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Young-Sik Ghim, Amit Suratkar, Angela Davies, and Yun-Woo Lee "Absolute thickness measurement of silicon wafer using wavelength scanning interferometer", Proc. SPIE 8133, Dimensional Optical Metrology and Inspection for Practical Applications, 813312 (14 September 2011); https://doi.org/10.1117/12.898354

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