Broadband coherent Fourier scatterometry: A two-pulse approach

T.A. van der Sijs*, J. Rafighdoost, L. Siaudynite, H.P. Urbach, S.F. Pereira, O. El Gawhary

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

We demonstrate a broadband implementation of coherent Fourier scatterometry (CFS) using a supercontinuum source. Spectral information can be resolved by splitting the incident field into two pulses with a variable delay and interfering them at the detector after interaction with the sample, bearing similarities with Fourier-transform spectroscopy. By varying the time delay between the pulses, a collection of diffraction patterns is captured in the Fourier plane, thereby obtaining an interferogram for every camera pixel. Spectrally resolved diffraction patterns can then be retrieved with a per-pixel Fourier transform as a function of the delay. We show the physical principle that motivates the two-pulse approach, the experimental realization, and results for a silicon line grating. The presented implementation using a supercontinuum source offers a cost-effective way to acquire multi-wavelength CFS data over a wide wavelength range, with the potential to improve reconstruction robustness and sensitivity in applications such as dimensional metrology.
Original languageEnglish
Article number013702
Pages (from-to)013702-1-013702-10
Number of pages10
JournalReview of Scientific Instruments
Volume96
Issue number1
DOIs
Publication statusPublished - 2025

Keywords

  • Scatterometry
  • Gratings
  • Metrology
  • Nanostructures
  • Optical scatterometry
  • Interferometry
  • Fourier transform spectroscopy

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