Magnetical asymmetry effect in capacitively coupled plasmas: effects of the magnetic field gradient, pressure, and gap length

Yang, Shali; Chang, Lijie; Ya, Zhang; Jiang, Wei

doi:10.1088/1361-6595/aab47e

Cited by 42 publications

(44 citation statements)

References 41 publications

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“…It is shown that high plasma density and thereby high ion flux can be achieved even at a very weak external magnetic field (~ 10 G) where ion energy can also be optimized simultaneously [34][35][36][37][38]. It is also reported in the literature that using magnetic field asymmetry in single-frequency CCP can independently control the ion flux and ion energy [39][40]. Later Sharma et al demonstrated that enhancement in ion flux and effective control of ion energy can be achieved by imposing a uniform transverse magnetic field in low-pressure singlefrequency CCP [41].…”

Section: Introductionmentioning

confidence: 95%

High frequency sheath modulation and higher harmonic generation in a low pressure very high frequency capacitively coupled plasma excited by sawtooth waveform

Sharma

Sirse

Turner

2020

Plasma Sources Sci. Technol.

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A particle-in-cell simulation study is performed to investigate the discharge asymmetry, higher harmonic generations and electron heating mechanism in a low pressure capacitively coupled plasma excited by a saw-tooth like current waveform for different driving frequencies; 13.56 MHz, 27.12 MHz, and 54.24 MHz. Two current densities, 50 A m−2 and 100 A m−2 are chosen for a constant gas pressure of 5 mTorr in argon plasma. At a lower driving frequency, high frequency modulations on the instantaneous sheath electric field near to the grounded electrode are observed. These high frequency oscillations create multiple ionization beam like structures near to the sheath edge that drives the plasma density in the discharge and responsible for discharge/ionization asymmetry at lower driving frequency. Conversely, the electrode voltage shows higher harmonics generation at higher driving frequencies and corresponding electric field transients are observed into the bulk plasma. At lower driving frequency, the electron heating is maximum near to the sheath edge followed by electron cooling within plasma bulk, however, alternate heating and cooling i.e. burst like structures are obtained at higher driving frequencies. These results suggest that electron heating in these discharges will not be described accurately by simple analytical models.

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Section: Introductionmentioning

confidence: 95%

High frequency sheath modulation and higher harmonic generation in a low pressure very high frequency capacitively coupled plasma excited by sawtooth waveform

Sharma

Sirse

Turner

2020

Plasma Sources Sci. Technol.

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“…Other recent studies devoted to CCP operation in the presence of an external magnetic field 26,27,34 , have explored somewhat different effects. S. Yang et al 35,36 have used an asymmetric magnetic field with variable gradients to create asymmetry in the configuration of a CCP device. Their particle simulation studies show that the magnetic field asymmetry provides a means of independently controlling the ion flux and ion energy.…”

mentioning

confidence: 99%

Spatial symmetry breaking in single-frequency CCP discharge with transverse magnetic field

et al. 2018

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An independent control of the flux and energy of ions impacting on an object immersed in a plasma is often desirable for many industrial processes such as microelectronics manufacturing. We demonstrate that a simultaneous control of these quantities is possible by a suitable choice of a static magnetic field applied parallel to the plane electrodes in a standard single frequency capacitively coupled plasma device. Our particle-in-cell simulations show a 60% reduction in the sheath width (that improves control of ion energy) and a four fold increase in the ion flux at the electrode as a consequence of the altered ion and electron dynamics due to the ambient magnetic field. A detailed analysis of the particle dynamics is presented and the optimized operating parameters of the device are discussed. The present technique offers a simple and attractive alternative to conventional dual frequency based devices that often suffer from undesirable limitations arising from frequency coupling and electromagnetic effects.

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“…The plasma uniformity can also be tuned by adjusting the discharge asymmetry, which can be formed either geometrically, [175][176][177] electrically, [178][179][180][181] or magnetically. [182][183][184][185] In a large-area, dual-frequency (40.68 MHz/81.36MHz) CCP in hydrogen, Schüngel et al [181] demonstrated that the lateral inhomogeneities caused by SWEs can be mitigated by changing the discharge symmetry via the electrical asymmetry effect (EAE), i.e., by tuning the phase shift between the two applied frequencies. However, the underlying mechanism of the influence of discharge symmetry on the nonlinear harmonics and standing waves was not clarified.…”

Section: Methods To Optimize the Plasma Uniformitymentioning

confidence: 99%

Fundamental study towards a better understanding of low pressure radio-frequency plasmas for industrial applications

Liu¹,

Zhang²,

Zhao³

et al. 2022

Chinese Phys. B

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Two classic radio-frequency (RF) plasmas, i.e., the capacitively and the inductively coupled plasma (CCP and ICP), are widely employed in material processing, e.g., etching and thin film deposition, etc. Since RF plasmas are usually operated in particular circumstances, e.g., low pressures (mTorr ~ Torr), high-frequency electric field (13.56 MHz ~200 MHz), reactive feedstock gases, diverse reactor configurations, etc., a variety of physical phenomena, e.g., electron resonance heating, discharge mode transitions, striated structures, standing wave effects, etc., arise. These physical effects could significantly influence plasma-based material processing. Therefore, understanding the fundamental processes of RF plasma is not only of fundamental interest, but also of practical significance for the improvement of the performance of the plasma sources. In this article, we review the major progresses that have been achieved in the fundamental study on the RF plasmas, and the topics include 1) electron heating mechanism, 2) plasma operation mode, 3) pulse modulated plasma, and 4) electromagnetic effects. These topics cover the typical issues in RF plasma field, ranging from fundamental to application.

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Magnetical asymmetry effect in capacitively coupled plasmas: effects of the magnetic field gradient, pressure, and gap length

Cited by 42 publications

References 41 publications

High frequency sheath modulation and higher harmonic generation in a low pressure very high frequency capacitively coupled plasma excited by sawtooth waveform

High frequency sheath modulation and higher harmonic generation in a low pressure very high frequency capacitively coupled plasma excited by sawtooth waveform

Spatial symmetry breaking in single-frequency CCP discharge with transverse magnetic field

Fundamental study towards a better understanding of low pressure radio-frequency plasmas for industrial applications

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