Electron heating mode transitions in dual frequency capacitive discharges

Abstract. Radio-frequency discharges are practically and scientifically interesting. A practical understanding of such discharges requires, among other things, a quantitative appreciation of the mechanisms involved in heating electrons, since this heating is the proximate cause of the ionization that sustains the plasma. When these discharges are operated at sufficiently low pressure, collisionless electron heating can be an important and even the dominant mechanism. Since the low pressure regime is important for many applications, understanding collisionless heating is both theoretically and practically important. This review is concerned with the state of theoretical knowledge of collisionless heating in both inductive and capacitive discharges.

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“…The curve denoted "Lieberman" corresponds to Eq. (54), that denoted "Kaganovich et al" to Eq. (55) and that denoted "Gozadinos et al" to Eq.…”

Section: Discussionmentioning

confidence: 99%

Collisionless heating in radio-frequency discharges: a review

Turner¹

2009

J. Phys. D: Appl. Phys.

121

117

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“…This effect can be enhanced in dual frequency plasmas. 7,8 In addition, secondary electrons created by ion bombardment of the momentary cathode can accelerate to the full sheath potential ͑several hundred eV at the peak of the applied rf voltage͒ and enter the plasma, creating a ͑usually small͒ population of very high energy electrons. Langmuir probes cannot detect these electrons, since they will be masked by a large positive ion current.…”

Section: B Electron Temperaturementioning

confidence: 99%

“…Many theoretical investigations of 2f-CCP have been carried out. Kawamura et al 6 and Turner and Chabert 7,8 discussed electron heating mechanisms. Kawamura et al 6 developed an analytical stochastic heating model that was in agreement with their particle-in-cell ͑PIC͒ simulation.…”

Section: Introductionmentioning

confidence: 99%

Measurement of electron temperatures and electron energy distribution functions in dual frequency capacitively coupled CF4/O2 plasmas using trace rare gases optical emission spectroscopy

Chen

Donnelly

Economou

et al. 2009

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Measurements of electron temperatures ͑T e ͒ and electron energy distribution functions ͑EEDFs͒ in a dual frequency capacitively coupled etcher were performed by using trace rare gas optical emission spectroscopy ͑TRG-OES͒. The parallel plate etcher was powered by a high frequency ͑60 MHz͒ "source" top electrode and a low frequency ͑13.56 MHz͒ "substrate" bottom electrode. T e first increased with pressure up to ϳ20 mTorr and then decreased at higher pressures. Increasing the bottom rf power resulted in higher electron temperatures. Electron temperatures in 90% CF 4 +10% O 2 plasmas were similar to those in 80% CF 4 +20% O 2 plasmas. EEDF exhibited bi-Maxwellian characteristics with enhanced high energy tail, especially at pressures Ͼ20 mTorr.

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“…For many applications of capacitively coupled radio frequency ͑CCRF͒ discharges, separate control of ion energy and ion flux at a processing surface is of major importance. 1 In "classical" dual frequency capacitive discharges operated at two substantially different frequencies [2][3][4][5][6][7][8][9][10] this separate control is limited by the coupling of both frequencies 2,3 and the effect of secondary electrons. 10,11 These limitations can be overcome by driving one electrode with a voltage waveform ϳ ͑t , ͒, which is the sum of a fundamental frequency f and its second harmonic with fixed, but adjustable phase shift between the driving harmonics:…”

Section: Introductionmentioning

confidence: 99%

Power absorption in electrically asymmetric dual frequency capacitive radio frequency discharges

et al. 2011

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The symmetry of capacitive radio frequency discharges can be controlled via the electrical asymmetry effect by driving one electrode with a fundamental frequency and its second harmonic. In such electrically asymmetric discharges, the mean ion energies at both electrodes are controlled separately from the ion flux by tuning the phase angle between the harmonics at fixed voltage amplitudes. Here, the question why the ion flux is nearly independent of is answered by investigating the power absorbed by the electrons P e as a function of and time experimentally, by a particle in cell simulation, and an analytical model. The dynamics of P e is understood by the model and is found to be strongly affected by the choice of. However, on time average, P e is nearly constant, independently of. Thus, the ion flux remains approximately constant. In addition, it is shown that the absolute value of the individual voltages across the powered and grounded electrode sheath vary linearly with the dc self-bias. However, their sum remains constant. This yields, in combination with the constancy of the ion flux, a constant power absorbed by the ions and, in conclusion, a total power absorption that is independent of .

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Electron heating mode transitions in dual frequency capacitive discharges

Cited by 28 publications

References 10 publications

Collisionless heating in radio-frequency discharges: a review

Collisionless heating in radio-frequency discharges: a review

Measurement of electron temperatures and electron energy distribution functions in dual frequency capacitively coupled CF4/O2 plasmas using trace rare gases optical emission spectroscopy

Power absorption in electrically asymmetric dual frequency capacitive radio frequency discharges

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