Aberration calibration and correction with nano-scatterers in digital holographic microscopy for semiconductor metrology

Christos Messinis*, Theodorus T.M. van Schaijk, Nitesh Pandey, Armand Koolen, Ilan Shlesinger, Xiaomeng Liu, Stefan Witte, Johannes F.D.E. Boer, Arie Den Boef

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Overlay metrology measures pattern placement between two layers in a semiconductor chip. The continuous shrinking of device dimensions drives the need to explore novel optical overlay metrology concepts that can address many of the existing metrology challenges. We present a compact dark-field digital holographic microscope that uses only a single imaging lens. Our microscope offers several features that are beneficial for overlay metrology, like a large wavelength range. However, imaging with a single lens results in highly aberrated images. In this work, we present an aberration calibration and correction method using nano-sized point scatterers on a silicon substrate. Computational imaging techniques are used to recover the full wavefront error, and we use this to correct for the lens aberrations. We present measured data to verify the calibration method and we discuss potential calibration error sources that must be considered. A comparison with a ZEMAX calculation is also presented to evaluate the performance of the presented method.

Original languageEnglish
Pages (from-to)38237-38256
Number of pages20
JournalOptics Express
Volume29
Issue number23
DOIs
Publication statusPublished - 8 Nov 2021

Bibliographical note

Publisher Copyright:
© 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

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