The effect of the driving frequencies on the electrical asymmetry of dual-frequency capacitively coupled plasmas

I. Korolov, Z. Donkó, Uwe Czarnetzki, Julian Schulze

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

In capacitively coupled radio frequency discharges driven by two consecutive phase-locked harmonics, the electrical asymmetry effect (EAE) allows one to generate a dc self-bias as a function of the phase shift, θ, between the driving harmonics. If the two frequencies are chosen to be 13.56 and 27.12MHz, the mean ion energy at both electrodes can be varied by a factor of about 2 by tuning θ at nearly constant ion flux. Until now the EAE has only been investigated in discharges operated at a fundamental frequency of f=13.56MHz. Here, we study the effect of changing this fundamental frequency on the performance of the EAE, i.e. on the electrical generation of a dc self-bias, the control range of the mean ion energy, and on the ion flux at both electrodes as a function of θ, by kinetic particle-in-cell/Monte Carlo simulations and theoretical modelling. We use argon gas and cover a wide range of fundamental frequencies (0.5MHzf60MHz) and secondary electron yields. We find that the performance of the EAE is significantly worse at lower frequencies, i.e. the control range of the dc self-bias and, thus, the control range of the mean ion energy are strongly reduced. Based on the analytical model (i) the enhanced charged dynamics at lower frequencies and (ii) the transition of the electron heating mode induced by changing f are found to be the reasons for this effect.

Original languageEnglish
Article number465205
JournalJournal of Physics D: Applied Physics
Volume45
Issue number46
DOIs
Publication statusPublished - Nov 21 2012

Fingerprint

asymmetry
Ions
trajectory control
Plasmas
ions
Fluxes
Electrodes
Electrons
Argon
low frequencies
harmonics
radio frequency discharge
Electron transitions
electrodes
Phase shift
Analytical models
Tuning
Gases
energy
electrons

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

Cite this

The effect of the driving frequencies on the electrical asymmetry of dual-frequency capacitively coupled plasmas. / Korolov, I.; Donkó, Z.; Czarnetzki, Uwe; Schulze, Julian.

In: Journal of Physics D: Applied Physics, Vol. 45, No. 46, 465205, 21.11.2012.

Research output: Contribution to journalArticle

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