Space and phase resolved plasma parameters in an industrial dual-frequency capacitively coupled radio-frequency discharge

Schulze, Julian; Gans, Timo; O’Connell, Deborah; Czarnetzki, Uwe; Ellingboe, A. R.; Turner, M. M.

doi:10.1088/0022-3727/40/22/022

Cited by 125 publications

(134 citation statements)

References 24 publications

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“…Figure 4 shows the measured spatio-temporal electron impact excitation rate from the ground state into N e2p 1 in such a discharge operated at 65 Pa with an electrode gap of 1.2 cm [22,46,47]. The experimental setup is described in detail elsewhere [22].…”

Section: Electron Dynamics In Classical Dual Frequency Dischargesmentioning

confidence: 99%

Phase resolved optical emission spectroscopy: a non-intrusive diagnostic to study electron dynamics in capacitive radio frequency discharges

Schulze¹,

Schüngel²,

Donkó³

et al. 2010

J. Phys. D: Appl. Phys.

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118

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To cite this version:J Schulze, E Schüngel, Z Donkó, D Luggenhölscher, U Czarnetzki. Phase resolved optical emission spectroscopy: a non-intrusive diagnostic to study electron dynamics in capacitive radio frequency discharges. Journal of Physics D: Applied Physics, IOP Publishing, 2010, 43 (12) Abstract. Various types of capacitively coupled radio frequency (CCRF) discharges are frequently used for different applications ranging from chip and solar cell manufacturing to the creation of biocompatible surfaces. In many of these discharges electron heating and electron dynamics are not fully understood. A powerful diagnostic to study electron dynamics in CCRF discharges is Phase Resolved Optical Emission Spectroscopy (PROES). It is non-intrusive and provides access to the dynamics of highly energetic electrons, that sustain the discharge via ionization, with high spatial and temporal resolution within the RF period. Based on a time dependent model of the excitation dynamics of specifically chosen rare gas levels PROES provides access to plasma parameters such as the electron temperature, electron density and electron energy distribution function (EEDF). In this work the method of PROES is reviewed and some examples of its application are discussed. First, the generation of highly energetic electron beams by the expanding sheath in geometrically symmetric as well as asymmetric discharges and their effect on the EEDF are investigated. Second, the physical nature of the frequency coupling in dual frequency discharges operated at substantially different frequencies is discussed. Third, the generation of electric field reversals during sheath collapse in single and dual frequency discharges is analyzed. Then excitation dynamics in an electrically asymmetric novel type of dual frequency discharge is studied. Finally, limitations of PROES are discussed.

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Section: Electron Dynamics In Classical Dual Frequency Dischargesmentioning

confidence: 99%

Phase resolved optical emission spectroscopy: a non-intrusive diagnostic to study electron dynamics in capacitive radio frequency discharges

Schulze¹,

Schüngel²,

Donkó³

et al. 2010

J. Phys. D: Appl. Phys.

Self Cite

110

118

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“…Many investigations into this control have focussed on driving CCPs with more than one frequency. The original concept was introduced by Löwe et al [4] and subsequently investigated by numerous authors [5][6][7][8][9][10][11]. The basic premise of the conventional dual frequency approach is to achieve independent control over the ion flux and bombardment energy by using a very high frequency to control the former and a low frequency to control the latter.…”

Section: Introductionmentioning

confidence: 99%

Controlling plasma properties under differing degrees of electronegativity using odd harmonic dual frequency excitation

Gibson

Gans

2017

Plasma Sources Sci. Technol.

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The charged particle dynamics in low-pressure oxygen plasmas excited by odd harmonic dual frequency waveforms (low frequency of 13.56 MHz and high frequency of 40.68 MHz) are investigated using a one-dimensional numerical simulation in regimes of both low and high electronegativity. In the low electronegativity regime, the time and space averaged electron and negative ion densities are approximately equal and plasma sustainment is dominated by ionisation at the sheath expansion for all combinations of low and high frequency and the phase shift between them. In the high electronegativity regime, the negative ion density is a factor of 15-20 greater than the low electronegativity cases. In these cases, plasma sustainment is dominated by ionisation inside the bulk plasma and at the collapsing sheath edge when the contribution of the high frequency to the overall voltage waveform is low. As the high frequency component contribution to the waveform increases, sheath expansion ionisation begins to dominate. It is found that the control of the average voltage drop across the plasma sheath and the average ion flux to the powered electrode are similar in both regimes of electronegativity, despite the differing electron dynamics using the considered dual frequency approach. This offers potential for similar control of ion dynamics under a range of process conditions, independent of the electronegativity. This is in contrast to ion control offered by electrically asymmetric waveforms where the relationship between the ion flux and ion bombardment energy is dependent upon the electronegativity.

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“…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. 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.…”

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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Space and phase resolved plasma parameters in an industrial dual-frequency capacitively coupled radio-frequency discharge

Cited by 125 publications

References 24 publications

Phase resolved optical emission spectroscopy: a non-intrusive diagnostic to study electron dynamics in capacitive radio frequency discharges

Phase resolved optical emission spectroscopy: a non-intrusive diagnostic to study electron dynamics in capacitive radio frequency discharges

Controlling plasma properties under differing degrees of electronegativity using odd harmonic dual frequency excitation

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

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