Spatial Profile Measurements of Charged Particles in Capacitively-Coupled    RF (13.56 MHz) Oxygen Discharges

Kaga, Kouji; Kimura, Takashi; Ohe, K.

doi:10.1143/jjap.40.330

Cited by 7 publications

(4 citation statements)

References 10 publications

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“…A similar pressure dependence of α peak was observed before [41,42]. Other groups found α int to increase as a function of pressure in single frequency capacitive discharges [50,51]. However, a direct comparison of the results is not possible due to the strong dependence of the electronegativity on all discharge parameters, e.g.…”

Section: Control Of the Density Profilessupporting

confidence: 73%

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 Density Profilessupporting

confidence: 73%

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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“…by Katsch et al [30], Stoffels et al [63] and Kuellig et al [64] concluded in electronegativity values between 1 and 10. In the measurements of Kaga et al [65] values up to 20 were found. (ii) Most of the above experiments have been conducted at power density levels much higher than those used by Derzsi et al [28,36] and showed 14 A c c e p t e d M a n u s c r i p t strong indications that the electronegativity increases towards lower power densities.…”

Section: Model Of the Electric Field Generationmentioning

confidence: 84%

Electron power absorption dynamics in magnetized capacitively coupled radio frequency oxygen discharges

Wang

Wen

Hartmann

et al. 2020

Plasma Sources Sci. Technol.

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The influence of a uniform magnetic field parallel to the electrodes on radio frequency capacitively coupled oxygen discharges driven at 13.56 MHz at a pressure of 100 mTorr is investigated by one-dimensional Particle-in-Cell/Monte Carlo collision (1D PIC/MCC) simulations. Increasing the magnetic field from 0 to 200 G is found to result in a drastic enhancement of the electron and the O + 2 ion density due to the enhanced confinement of electrons by the magnetic field. The time and space averaged O − ion density, however, is found to remain almost constant, since both the dissociative electron attachment (production channel of O − ) and the associative electron detachment rate due to the collisions of negative ions with oxygen metastables (main loss channel of O − ) are enhanced simultaneously. This is understood based on a detailed analysis of the spatio-temporal electron dynamics.The nearly constant O − density in conjunction with the increased electron density causes a significant reduction of the electronegativity and a pronounced change of the electron power absorption dynamics as a function of the externally applied magnetic field. While at low magnetic fields the discharge is operated in the electronegative Drift-Ambipolar (DA) mode, a transition to the electropositive α-mode is induced by increasing the magnetic field. Meanwhile, a strong electric field reversal is generated near each electrode during the local sheath collapse at high magnetic fields, which locally enhances the electron power absorption. A model of the electric field generation reveals that the reversed electric field is caused by the reduction of the electron flux to the electrodes due to their trapping by the magnetic field.The consequent changes of the plasma properties are expected to affect the applications of such discharges in etching, deposition and other semiconductor processes.

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“…Similarly, Katsch et al [66] estimated the electronegativity in the discharge center of a capacitively coupled oxygen discharge, with aluminum electrodes with 2.54 cm separation, to be roughly 2 at 103 mTorr and 150 V and to fall below unity at 280 V. We would expect the electronegativity to decrease for aluminum electrodes and higher pressure. For higher pressures Küllig et al [67] reported electronegativity of 5 -6 at 225 mTorr in an asymmetric capacitively coupled discharge with stainless steel electrodes and Kaga et al [68] measured center electronegativity of 7.4 -11.6 at 100 mTorr and 10.8 -18.6 at 500 mTorr with aluminum electrodes with spacing of 6 cm. The time averaged electron density profile is shown in Figure 4.…”

Section: Global Model -Partial Pressuresmentioning

confidence: 99%

The role of surface quenching of the singlet delta molecule in a capacitively coupled oxygen discharge

Proto¹,

Guðmundsson²

2018

Plasma Sources Sci. Technol.

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We use the one-dimensional object-oriented particle-in-cell Monte Carlo collision code oopd1 to explore the influence of the surface quenching of the singlet delta metastable molecule O2(a 1 ∆g) on the electron heating mechanism, and the electron energy probability function (EEPF), in a single frequency capacitively coupled oxygen discharge. When operating at low pressure (10 mTorr) varying the surface quenching coefficient in the range 0.00001 -0.1 has no influence on the electron heating mechanism and electron heating is dominated by drift-ambipolar (DA) heating in the plasma bulk and electron cooling is observed in the sheath regions. As the pressure is increased to 25 mTorr the electron heating becomes a combination of DA-mode and α−mode heating, and the role of the DA-mode decreases with decreasing surface quenching coefficient. At 50 mTorr electron heating in the sheath region dominates. However, for the highest quenching coefficient there is some contribution from the DA-mode in the plasma bulk, but this contribution decreases to almost zero and pure α−mode electron heating is observed for a surface quenching coefficient of 0.001 or smaller.

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Spatial Profile Measurements of Charged Particles in Capacitively-Coupled RF (13.56 MHz) Oxygen Discharges

Cited by 7 publications

References 10 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 power absorption dynamics in magnetized capacitively coupled radio frequency oxygen discharges

The role of surface quenching of the singlet delta molecule in a capacitively coupled oxygen discharge

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