Quantitative depth evaluation of microgrooves on polymer material beyond the diffraction limit

Shiwei Ye, Satoru Takahashi*, Masaki Michihata, Kiyoshi Takamasu, Hans Nørgaard Hansen, Matteo Calaon

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The demand for dimensional micro and nano metrology is evident, and with the miniaturization process of microstructures and the trend towards using polymer material, the available technologies are imperative. This paper proposes a quantitative depth evaluation method for microgrooves with width less than the diffraction limit and a measurement system capable of depth detection on polymer materials. The depth of microgrooves can be quantitatively related to the near-field optical phase difference, which cannot be practically observed but can be computed from practical far-field observations by proposed depth evaluation method. The developed measurement system uses low-coherence illumination to reduce the spatial speckle noise and multiple interference noise on transparent polymer materials. Microgrooves (nominal width = 300 nm, Rayleigh Criterion of measurement system = 772 nm) on a transparent polymer surface (thermoplastic COC 5013L molded sample) were measured, and the results were compared with AFM measurements. It is demonstrated that the proposed method is instrumental in evaluating the depth of microgrooves beyond the diffraction limit with an accuracy of less than 10% of the test depth.
Original languageEnglish
JournalPrecision Engineering
Volume59
Pages (from-to)56-65
ISSN0141-6359
DOIs
Publication statusPublished - 2019

Keywords

  • Linnik interferometry
  • Low-coherence illumination
  • Micro and nano metrology
  • Optical measurement
  • Quantitative depth evaluation
  • Super-resolution technology

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