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Electron heating modes and frequency coupling effects in dual-frequency capacitive CF4 plasmas

Derzsi, Aranka and Schüngel, Edmund and Donkó, Zoltán and Schulze, Julian (2014) Electron heating modes and frequency coupling effects in dual-frequency capacitive CF4 plasmas. Open Chemistry, 13 (1). pp. 346-361. ISSN 2391-5420

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Abstract

Two types of capacitive dual-frequency discharges, used in plasma processing applications to achieve the separate control of the ion flux, Гi, and the mean ion energy, <E >, at the electrodes, operated in CF , i4 are investigated by particle-in-cell simulations: (i) In classical dual-frequency discharges, driven by significantly different frequencies (1.937 MHz + 27.12 MHz), <Ei> and Гi are controlled by the voltage amplitudes of the low-frequency and high-frequeny components, ΦLF and ΦHF, respectively. (ii) In electrically asymmetric (EA) discharges, operated at a fundamental frequency and its second harmonic (13.56 MHz + 27.12 MHz), ΦLF and ΦHF control Гi, whereas the phase shift between the driving frequencies, θ, is varied to adjust <Ei>. We focus on the effect of changing the control parameter for <Ei> on the electron heating and ionization dynamics and on Гi. We find that in both types of dual-frequency strongly electronegative discharges, changing the control parameter results in a complex effect on the electron heating and ionization dynamics: in classical dual-frequency discharges, besides the frequency coupling affecting the sheath expansion heating, additional frequency coupling mechanisms influence the electron heating in the plasma bulk and at the collapsing sheath edge; in EA dual-frequency discharges the electron heating in the bulk results in asymmetric ionization dynamics for values of θ around 45°, i.e., in the case of a symmetric applied voltage waveform, that affects the dc self-bias generation.

Item Type: Article
Subjects: Q Science / természettudomány > QC Physics / fizika
Depositing User: Dr Zoltán Donkó
Date Deposited: 08 Jan 2016 12:06
Last Modified: 04 Apr 2023 11:20
URI: http://real.mtak.hu/id/eprint/31964

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