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Etching Mechanisms and Surface Conditions for SiOxNy Thin Films in CF4 + CHF3 + O2 Inductively Coupled Plasma

  • Junmyung Lee
  • Jihun Kim
  • Alexander Efremov
  • Changmok Kim
  • Hyun Woo Lee
  • Kwang-Ho KwonEmail author
Original Paper
  • 9 Downloads

Abstract

In this work, we investigated the etching characteristics of SiOxNy thin films in CF4 + CHF3 + O2 inductively coupled radiofrequency (13.56 MHz) plasma. SiOxNy etching rates were measured as functions of the CF4/CHF3 mixing ratio at constant O2 fraction, gas pressure (10 mTorr), input power (500 W) and bias power (100 W). The conditions of the etched surfaces were examined by X-ray photoelectron spectroscopy, atomic force microscopy and contact angle measurements. Data on internal plasma parameters and steady-state plasma composition were obtained by Langmuir probe diagnostics and zero-dimensional plasma modeling. It was found that the substitution of CF4 for CHF3 suppresses the SiOxNy etching rate as well as results in increasing both amount of residual fluorocarbon polymer and SiOxNy/Si etching selectivity. The SiOxNy etching mechanism was analyzed by considering the relationships between measured etching rates and model-predicted fluxes of active species (F atoms, CFx radicals and positive ions). It was proposed that the SiOxNy etching process: (1) exhibits features of ion-assisted chemical reactions in the neutral-flux-limited mode, and (2) involves the contributions of by HF molecules. The effective probability of the SiOxNy + F reaction is correlated with the amount of deposited fluorocarbon polymer while the hydrophobic nature of the plasma-treated SiOxNy surface confirms the presence of a continuous fluorocarbon polymer film.

Keywords

SiOxNy Fluorocarbon plasma Etching rate Etching selectivity F atom flux Polymerizing species flux Ion energy flux Reaction probability 

Notes

Acknowledgements

This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry and Energy (MOTIE) of the Republic of Korea (No. 20172010105910).

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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  • Junmyung Lee
    • 1
  • Jihun Kim
    • 1
  • Alexander Efremov
    • 2
  • Changmok Kim
    • 1
  • Hyun Woo Lee
    • 3
  • Kwang-Ho Kwon
    • 1
    Email author
  1. 1.Department of Control and Instrumentation EngineeringKorea UniversitySejongRepublic of Korea
  2. 2.Department of Electronic Devices and Materials TechnologyState University of Chemistry and TechnologyIvanovoRussia
  3. 3.Department of Aeronautic Electric EngineeringHanseo UniversitySeosanRepublic of Korea

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