Electrostatic modelling of dual frequency rf plasma discharges

Boyle, P C; Ellingboe, A. R.; Turner, M. M.

doi:10.1088/0963-0252/13/3/016

Cited by 156 publications

(147 citation statements)

References 17 publications

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“…In most of these applications, separate control of the ion flux and the ion bombarding energy onto the processing surface is of great importance for manufacturing efficiency and quality control [1]. The concept of dual frequency discharges, i.e., driving the plasma with two substantially different radio frequencies, had, therefore, been introduced as a promising way to achieve this separate control [2][3][4][5][6][7][8]. 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.…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

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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“…This background makes an enquiry into the physics of dual frequency discharges desirable, with the aim of establishing simple models based on an understanding of the dominant physical effects. These are not a trivial superposition of the effects of the two frequencies acting separately, as has already been shown [2][3][4][5][6]. In this Letter we discuss the relative importance of two important electron heating mechanisms, Ohmic heating and collisionless or stochastic heating.…”

mentioning

confidence: 70%

Electron heating mode transitions in dual frequency capacitive discharges

Turner

Chabert

2006

Applied Physics Letters

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We consider electron heating in the sheath regions of capacitive discharges excited by a combination of two frequencies, one much higher than the other. There is a common supposition that in such discharges the higher frequency is the dominant source of electron heating. In this letter, we discuss closed analytic expressions quantifying the Ohmic and collisionless electron heating in a dual frequency discharge. In both cases, we show that the lower frequency parameters strongly influence the heating effect. Moreover, this influence is parametrically different, so that the dominant heating mechanism may be changed by varying the low frequency current density. * Electronic address: miles.turner@dcu.ie 1

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“…Where s and V s are the sheath width and time averaged sheath potential respectively [8]. The shape of the IEDF can be determined from the ratio of the ion transit time ( ion τ ) to the RF period ( rf τ ) [2,8,9].…”

Section: Experimental Setup and Backgroundmentioning

confidence: 99%

“…The shape of the IEDF can be determined from the ratio of the ion transit time ( ion τ ) to the RF period ( rf τ ) [2,8,9]. If the ratio 1 >> rf ion τ τ , regime is high -frequency type, and ions can no longer respond to the instantaneous electric field, but the ion energy will depend on the time-averaged sheath potential.…”

Section: Experimental Setup and Backgroundmentioning

confidence: 99%

Analysis of Dual Frequency Confined Capacitively Coupled Plasma at Low Power

Helhel

2006

Int J Infrared Milli Waves

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Confined dual frequency hydrogen plasma discharge has been investigated with microwave interferometer method and radial profiles are taken by Abel inversion technique. Dual radio-frequency sources, operating at 27.12MHz and 1.94MHz, are coupled to each other through the plasma. 27.12MHz RF power is used to enhance plasma density and 1.94MHz power is used to enhance ion acceleration energy to the electrode. Radial density profiles has been taken for comparing the effects of low frequency source that the secondary RF source causes reduction in plasma density due to the sheath expansion. Instead radial density profile is assumed as flat by most of the models, there is about 2.5eV of potential drop occurs from centre to boundary at 40W of primary source power. It has been observed that increasing sheath width (increasing the secondary source power to primary source power) reduces the bulk plasma volume and makes potential profile flattening in y direction. While the high frequency power is dissipated by electrons in the bulk plasma; low frequency power is mostly dissipated by ions in the sheath region. Using both high and low frequency power, we may control plasma density and ion acceleration energy to the electrode simultaneously.

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Electrostatic modelling of dual frequency rf plasma discharges

Cited by 156 publications

References 17 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

Electron heating mode transitions in dual frequency capacitive discharges

Analysis of Dual Frequency Confined Capacitively Coupled Plasma at Low Power

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