22 May 2017 Applications of model-based transparent surface films analysis using coherence-scanning interferometry
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Optical Engineering, 56(11), 111709 (2017). doi:10.1117/1.OE.56.11.111709
Abstract
Surface metrology must increasingly contend with submicron films, whose prevalence now extends to products well beyond semiconductor devices. For optical technologies such as coherence-scanning interferometry (CSI), transparent submicron films pose a dual challenge: film effects can distort the measured top surface topography map and metrology requirements may now include three-dimensional maps of film thickness. Yet CSI’s sensitivity also presents an opportunity: modeling film effects can extract surface and thickness information encoded in the distorted signal. Early model-based approaches entailed practical trade-offs between throughput and field of view and restricted the choice of objective magnification. However, more recent advances allow full-field surface films analysis using any objective, with sample-agnostic calibration and throughput comparable to film-free measurements. Beyond transparent films, model-based CSI provides correct topography for any combination of dissimilar materials with known visible-spectrum refractive indices. Results demonstrate single-nm self-consistency between topography and thickness maps.
Martin F. Fay, Thomas Dresel, "Applications of model-based transparent surface films analysis using coherence-scanning interferometry," Optical Engineering 56(11), 111709 (22 May 2017). http://dx.doi.org/10.1117/1.OE.56.11.111709
Submission: Received 1 January 2017; Accepted 27 April 2017
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KEYWORDS
Model-based design

Interferometry

3D modeling

Metrology

Refractive index

Calibration

Statistical analysis

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