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Plasma Parameters and Silicon Etching Kinetics in C4F8 + O2 + Ar Gas Mixture: Effect of Component Mixing Ratios

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Abstract

In this work, we investigated the possibidlxlity to control both gas-phase chemistry and silicon etching kinetics in C4F8 + O2 + Ar inductively coupled plasma by changes in O2/Ar, C4F8/O2 and C4F8/Ar mixing ratios at the constant fraction of the rest component (50%), gas pressure (10 mTorr), input power (700 W) and bias power (200 W). The combination of plasma diagnostics and modeling tools allowed one: (a) to compare the effects of gas mixing ratios on both steady-state plasma parameters and densities of active species; (b) to figure out key processes which determine the fluorine atom formation/decay balance in each gas system; and (c) to analyze the differences in Si etching kinetics in terms of process-condition-dependent effective reaction probability. It was shown that the maximum changes in gas-phase chemistry take place in O2-rich plasmas due to CFx + O/O(1D) → CFx−1O + F, CFxO + e → CFx−1O + F + e and CFO + O/O(1D) → CO2 + F stepwise dissociation pathways. It was suggested also that the effective probability for Si + xF → SiFx reaction may be controlled by either fluorocarbon film thickness (in C4F8—rich plasmas) or O atom flux (in Ar and O2—rich plasmas) through the balance of adsorption sites on the etched surface.

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Acknowledgements

The work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20172010105910) (B. J. Lee, Y. Nam and K.-H. Kwon).

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Authors and Affiliations

  1. Department of Control and Instrumentation Engineering, Korea University, Sejong, 30019, Republic of Korea

    Byung Jun Lee, Yunho Nam & Kwang-Ho Kwon

  2. Department of Electronic Devices and Materials Technology, State University of Chemistry and Technology, 7 Sheremetevsky av., Ivanovo, Russia, 153000

    Alexander Efremov

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  1. Byung Jun Lee
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  2. Alexander Efremov
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  3. Yunho Nam
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  4. Kwang-Ho Kwon
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Correspondence to Kwang-Ho Kwon.

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Lee, B.J., Efremov, A., Nam, Y. et al. Plasma Parameters and Silicon Etching Kinetics in C4F8 + O2 + Ar Gas Mixture: Effect of Component Mixing Ratios. Plasma Chem Plasma Process 40, 1365–1380 (2020). https://doi.org/10.1007/s11090-020-10097-9

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