The electrical asymmetry effect in capacitively coupled radio frequency discharges – measurements of dc self bias, ion energy and ion flux

Schulze, Julian; Schüngel, Edmund; Czarnetzki, Uwe

doi:10.1088/0022-3727/42/9/092005

Cited by 160 publications

(211 citation statements)

References 26 publications

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“…Despite the small deviation at high pressure, which is due to the model assumption of a negligible voltage drop across the plasma bulk, this gives an excellent agreement. Similar to the results obtained in argon discharges [25,27,30], the dc selfbias changes almost linearly as a function of the phase angle in the range 0 • ≤ θ ≤ 90 • and 90 • ≤ θ ≤ 180 • . In this work, the EAE is tested experimentally for the first time in an electronegative discharge.…”

Section: Control Of the Electrical Symmetrysupporting

confidence: 84%

“…This is indicated by the comparison of the results in oxygen with the dc self-bias obtained by the analytical model assuming ε = 1 for all θ; it corresponds to the assumption of equal mean ion densities in both the powered and the grounded electrode sheath (see Eq. 5), which is well justified in geometrically symmetric argon discharges operated at relatively high pressures [25,27]. It should be noted that the experimentally obtained values of the dc self-bias are shifted towards smaller values due to the capacitive coupling between the glass cylinder confining the plasma radially and the outer chamber wall.…”

Section: Control Of the Electrical Symmetrysupporting

confidence: 53%

“…The experimental setup is similar to the one that has been used and described in previous studies [27]. Therefore, only a brief description is given here.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, the control ofη with the phase angle shown in Fig. 7 is the key to control the ion energy separately from the ion flux via the EAE, which has been examined in argon [24][25][26][27] and oxygen [36] discharges up to now.…”

Section: Control Of the Electrical Symmetrymentioning

confidence: 99%

“…However, it is known that the coupling of both frequencies [9][10][11][12][13][14][15][16][17][18][19] and the effect of secondary electrons [8,[20][21][22] places a strong limitation to realize this goal. A rather new approach was recently proposed to control the ion properties via the Electrical Asymmetry Effect (EAE) [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]: By applying a voltage waveform, that contains a fundamental frequency and (at least) one even harmonic, the symmetry of the discharge can be changed by tuning the phase angle between the driving harmonics. This in turn allows controling basic properties of the plasma, such as the dc self-bias, the position of the plasma bulk, and the ion energy at both electrodes while maintaining an almost constant ion flux.…”

Section: Introductionmentioning

confidence: 99%

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Control of plasma properties in capacitively coupled oxygen discharges via the electrical asymmetry effect

Schüngel¹,

Zhang²,

Iwashita³

et al. 2011

J. Phys. D: Appl. Phys.

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To cite this version:E Schüngel, Q-Z Zhang, S Iwashita, J Schulze, L-J Hou, et al.. Control of plasma properties in capacitively coupled oxygen discharges via the electrical asymmetry effect. Journal of Physics D: Applied Physics, IOP Publishing, 2011, 44 (28) Abstract. By using a combined experimental, numerical and analytical approach, we investigate the control of plasma properties via the Electrical Asymmetry Effect (EAE) in a capacitively coupled oxygen discharge. In particular, we present the first experimental investigation of the EAE in electronegative discharges. A dual-frequency voltage source of 13.56 MHz and 27.12 MHz is applied to the powered electrode and the discharge symmetry is controlled by adjusting the phase angle θ between the two harmonics. It is found that the bulk position and density profiles of positive ions, negative ions, and electrons have a clear dependence on θ, while the peak densities and the electronegativity stay rather constant, largely due to the fact that the time averaged power absorption by electrons is almost independent of θ. This indicates that the ion flux towards the powered electrode remains almost constant. Meanwhile, the dc self-bias and, consequently, the sheath widths and potential profile can be effectively tuned by varying θ. This enables a flexible control of the ion bombarding energy at the electrode. Therefore, our work proves the effectiveness of the EAE to realize separate control of ion flux and ion energy in electronegative discharges. At low pressure, the strength of resonance oscillations, which are found in the current of asymmetric discharges, can be controlled with θ.

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Section: Control Of the Electrical Symmetrysupporting

confidence: 84%

Section: Control Of the Electrical Symmetrysupporting

confidence: 53%

“…The experimental setup is similar to the one that has been used and described in previous studies [27]. Therefore, only a brief description is given here.…”

Section: Methodsmentioning

confidence: 99%

Section: Control Of the Electrical Symmetrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Control of plasma properties in capacitively coupled oxygen discharges via the electrical asymmetry effect

Schüngel¹,

Zhang²,

Iwashita³

et al. 2011

J. Phys. D: Appl. Phys.

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A Simple Model for Ion Flux‐Energy Distribution Functions in Capacitively Coupled Radio‐Frequency Plasmas Driven by Arbitrary Voltage Waveforms

Schüngel

Schulze

2016

Plasma Processes & Polymers

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The ion flux‐energy distribution function (IFEDF) is of crucial importance for surface processing applications of capacitively coupled radio‐frequency (CCRF) plasmas. Here, we propose a model that allows for the determination of the IFEDF in such plasmas for various gases and pressures in both symmetric and asymmetric configurations. A simplified ion density profile and a quadratic charge voltage relation for the plasma sheaths are assumed in the model, of which the performance is evaluated for single‐ as well as multi‐frequency voltage waveforms. The IFEDFs predicted by this model are compared to those obtained from PIC/MCC simulations and retarding field energy analyzer measurements. Furthermore, the development of the IFEDF shape and the ion dynamics in the plasma sheath region are discussed in detail based on the spatially and temporally resolved model data.

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Magnetical asymmetric effect in geometrically and electrically symmetric capacitively coupled plasma

Yang

Zhang

Wang

et al. 2017

Plasma Processes & Polymers

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Magnetical asymmetric effect (MAE) in a geometrically and electrically symmetric capacitively coupled plasma is investigated by a one‐dimensional implicit Particle‐in‐cell/Monte Carlo collision simulation. We applied four types of asymmetric magnetic field parallel to the electrodes and the discharge operates at a single‐frequency rf source of 13.56 MHz and 150 V in argon with the pressure of 30 mTorr. The simulation results show that the asymmetric magnetic field can generate a significant dc self‐bias, which is the result of a particle‐flux balance applied to each electrode. The asymmetric magnetic field with variable gradient can produce controllable asymmetry in the plasma density and ion flux profiles to each electrode, together with a significant change on IEDF shape and width on the powered electrode. It has demonstrated that the MAE is a promising approach to increase the ion flux and still make the ion energy be adjusted in a certain range, that is, independent control of ion flux and energy to the electrode. The results suggest that the MAE can be an effective means to control the plasma properties as an augmentation to conventional measures.

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The electrical asymmetry effect in capacitively coupled radio frequency discharges – measurements of dc self bias, ion energy and ion flux

Abstract: The recently theoretically predicted electrical asymmetry effect (EAE)

Cited by 160 publications

References 26 publications

Control of plasma properties in capacitively coupled oxygen discharges via the electrical asymmetry effect

Control of plasma properties in capacitively coupled oxygen discharges via the electrical asymmetry effect

A Simple Model for Ion Flux‐Energy Distribution Functions in Capacitively Coupled Radio‐Frequency Plasmas Driven by Arbitrary Voltage Waveforms

Magnetical asymmetric effect in geometrically and electrically symmetric capacitively coupled plasma

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