Reflectance metrology of thin films

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isbn9789526424149.pdf (3.11 MB)

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School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2025-03-07
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Date

2025

Department

Sähkötekniikan ja automaation laitos
Department of Electrical Engineering and Automation

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Mcode

Degree programme

Language

en

Pages

43 + app. 37

Series

Aalto University publication series Doctoral Theses, 38/2025

Abstract

This thesis investigates the application of reflectometry techniques for characterizing thin-film structures, with a focus on developing methods to analyse complex multilayer configurations. Accurate reflectance data is critical in reflectometry, therefore, the Richardson-Lucy bandwidth correction method was applied and tested on reflectance measurements of a 2-μm-thick SiO₂ layer on a silicon substrate. This evaluation assessed improvements, effects and artifacts the method might introduce on processed measured data. In parallel, a basic model of the PillarHall chip, featuring an air gap layer, was developed and analysed. This model employs a dedicated MATLAB code based on the transfer-matrix method to simulate the reflectance spectrum and fit it to the measured data, enabling the extraction of layers’ thicknesses of the studied sample. Building on the basic model, an advanced PillarHall model was created, designed not only to estimate layer thickness but also to determine the size of specific structural features. The findings underscore the importance of accurate, bandwidth-corrected reflectance spectra, as the precision of fitted model parameters correlates directly with the spectrum quality.

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Supervising professor

Ikonen, Erkki, Prof., Aalto University, Department of Electrical Engineering and Automation, Finland

Thesis advisor

Manoocheri, Farshid, D.Sc. (Tech.), Aalto University, Department of Information and Communications Engineering, Finland

Keywords

bandwidth correction, Richardson-Lucy method, reflectometry technique, thin film measurements, PillarHall, periodic microstructures

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Parts

  • [Publication 1]: Danilenko, Aleksandr; Rastgou, Masoud; Manoocheri, Farshid; Ikonen, Erkki. "Application of a bandwidth correction method to thin-film reflectance measurements" (submitted)
  • [Publication 2]: Danilenko, Aleksandr; Rastgou, Masoud; Manoocheri, Farshid; Kinnunen, Jussi; Korpelainen, Virpi; Lassila, Antti; Ikonen, Erkki. 2023. "Characterization of PillarHall test chip structures using a reflectometry technique". Measurement Science and Technology, 34(9), 094006.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202308014564
    DOI: 10.1088/1361-6501/acda54 View at publisher
  • [Publication 3]: Danilenko, Aleksandr; Rastgou, Masoud; Manoocheri, Farshid; Kinnunen, Jussi; Korpelainen, Virpi; Lassila, Antti; Ikonen, Erkki. "Reflectometry technique for study of complex multilayer micro- and nanostructures with lateral periodicity". Journal of Applied Physics (AIP Publishing) (accepted)

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https://urn.fi/URN:ISBN:978-952-64-2414-9

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[diss] Sähkötekniikan korkeakoulu / ELEC