Frequency coupling in low-pressure dual-frequency capacitively coupled plasmas revisited based on the Boltzmann term analysis

  • Electron power absorption dynamics is investigated in radio-frequency (RF) argon capacitively coupled plasmas (CCPs) at low pressure (4–70 Pa) excited by a dual-frequency waveform with frequencies of 27.12 MHz and 1.937 MHz. Based on the spatio-temporal dynamics of the ambipolar electric field a novel interpretation of the mechanism of frequency coupling is given, which is not based on the hard wall model, as in previous explanations. Within this framework, frequency coupling arises due to the decreased size of the ambipolar region outside the sheath when the low-frequency sheath is close to its full expansion, which leads to decreased ionization in this region. It is shown, under the circumstances considered here, ohmic power absorption is dominant. The spatio-temporally averaged ambipolar power absorption shows nonmonotonic behaviour as a function of pressure, first increasing, then, after reaching a local maximum, decreasing as the pressure is increased. It is shown, that the reason for this nonmonotonic behaviour is ultimately connected to the frequency coupling mechanism.

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Author:Máté VassORCiDGND, Li WangORCiDGND, Sebastian WilczekORCiDGND, Trevor LafleurORCiDGND, Ralf Peter BrinkmannORCiDGND, Zóltán DonkóORCiDGND, Julian SchulzeORCiDGND
Parent Title (English):Plasma sources science and technology
Publisher:IOP Publishing
Place of publication:Bristol, Vereinigtes Königreich
Document Type:Article
Date of Publication (online):2024/02/16
Date of first Publication:2022/11/07
Publishing Institution:Ruhr-Universität Bochum, Universitätsbibliothek
Tag:Boltzmann term analysis; capacitively coupled plasma; dual frequency discharges; electron power absorption; frequency coupling; particle-in-cell simulation
Issue:11, Artikel 115004
First Page:115004-1
Last Page:115004-12
Institutes/Facilities:Lehrstuhl für Angewandte Elektrodynamik und Plasmatechnik
Dewey Decimal Classification:Technik, Medizin, angewandte Wissenschaften / Elektrotechnik, Elektronik
open_access (DINI-Set):open_access
faculties:Fakultät für Elektrotechnik und Informationstechnik
Licence (English):License LogoCreative Commons - CC BY 4.0 - Attribution 4.0 International