Journal of Infrared and Millimeter Waves, Volume. 43, Issue 3, 354(2024)

Non-destructive thickness measurement with micron level accuracy based on a 4.3-THz quantum-cascade laser

Hong-Yi LI1,2, Zhi-Yong TAN1,2、*, Wen-Jian WAN1,2, and Jun-Cheng CAO1,2、**
Author Affiliations
  • 1National Key Laboratory of Materials for Integrated Circuits,Shanghai Institute of Microsystem and Information Technology,Chinese Academy of Sciences,Shanghai 200050,China
  • 2Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China
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    Figures & Tables(9)
    Terahertz homodyne detection system:(a) Schematic of the terahertz light path;(b) Photos of the experimental setup
    The measured terahertz beam spot including both the reference light and the interference fringes
    Schematic diagram of the optical path when the terahertz beam passes through the sample
    Theoretical curves of transmission phase (φ) changing with sample rotation angle (θ) under different thickness (T) conditions
    Thickness measurement results of silicon wafers numbered 1 (a),2 (b),and 3 (c) based on optical microscopes,as well as the measured length of a 1 mm standard microscale plate (d)
    Experimental results of transmission phase (φ) with the rotation angle (θ) after the terahertz light passes through the wafer (1+2) and the wafer (1+2+3)
    Variation of the calculated RMSE with the fitting thickness:(a) wafer (1+2);(b) wafer (1+2+3)
    Experimental (solid circle) and fitting (solid line) transmission phase with different rotation angle
    • Table 1. The nominal value and measurement results of the thicknes of different silicon wafers

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      Table 1. The nominal value and measurement results of the thicknes of different silicon wafers

      Wafer number

      Nominal thickness

      (μm)

      Thickness with an optical microscope

      (μm)

      Thickness with homodyne detection

      (μm)

      1500 ± 10500.00/
      2500 ± 10495.34/
      3500 ± 10510.09/
      1,21 000 ± 20995.43992.50
      1,2,31 500 ± 301 505.521 503.00
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    Hong-Yi LI, Zhi-Yong TAN, Wen-Jian WAN, Jun-Cheng CAO. Non-destructive thickness measurement with micron level accuracy based on a 4.3-THz quantum-cascade laser[J]. Journal of Infrared and Millimeter Waves, 2024, 43(3): 354

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    Paper Information

    Category: Research Articles

    Received: Aug. 28, 2023

    Accepted: --

    Published Online: Apr. 29, 2024

    The Author Email: Zhi-Yong TAN (zytan@mail.sim.ac.cn), Jun-Cheng CAO (jccao@mail.sim.ac.cn)

    DOI:10.11972/j.issn.1001-9014.2024.03.009

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