Dual-frequency capacitive discharges: Effect of low-frequency current on electron distribution function

Kim, H. C.; Lee, J. K.

doi:10.1063/1.1888325

Cited by 34 publications

(26 citation statements)

References 29 publications

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“…Various physical mechanisms produce coupling between the two frequencies, and these effects have been explored in general terms in a number of recent papers, e.g. [1,2,3,4,5,6]. The purpose of the present paper is to discuss the electron heating mechanisms that operate in dual-frequency discharges-in particular, to elucidate their nature and significance, and as far as possible supply convenient formulae that may be used as elements in a comprehensive theoretical understanding of these discharges.…”

Section: Introductionmentioning

confidence: 99%

Electron heating mechanisms in dual-frequency capacitive discharges

Turner

Chabert

2007

Plasma Sources Sci. Technol.

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Abstract. We discuss electron heating mechanisms in the sheath regions of dualfrequency capacitive discharges, with the twin aims of identifying the dominant mechanisms and supplying closed-form expressions from which the heating power can be estimated. We show that the heating effect produced by either Ohmic or collisionless heating is much larger when the discharge is excited by a superposition of currents at two frequencies than if either current had acted alone. This coupling effect occurs because the lower frequency current, while not directly heating the electrons to any great extent, strongly affects the spatial structure of the discharge in the sheath regions.

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Section: Introductionmentioning

confidence: 99%

Electron heating mechanisms in dual-frequency capacitive discharges

Turner

Chabert

2007

Plasma Sources Sci. Technol.

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“…19 Kim and Lee also reported that the EEDF evolves from Druyvesteyn to bi-Maxwellian as the rf frequency increases from 2 to 27 MHz. 20 Seo et al 21 and Gudmundsson 22 also reported that the EEDF in a planar inductive discharge appears to be Maxwellian at low pressures and evolves into a Druyvesteyn-like distribution at high pressures. Moreover, a careful account of the effect of the high-energy tail of Maxwellian distribution 23 often results in substantially higher rates of collision 24 and kinetic energy losses as compared with the Druyvesteyn-like distribution.…”

Section: Introductionmentioning

confidence: 92%

Electron/ion energy loss to discharge walls revised: A case study in low-temperature, thermally nonequilibrium plasmas

Ren

Ostrikov

2008

Physics of Plasmas

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Reliable calculations of the electron/ion energy losses in low-pressure thermally nonequilibrium low-temperature plasmas are indispensable for predictive modeling related to numerous applications of such discharges. The commonly used simplified approaches to calculation of electron/ion energy losses to the chamber walls use a number of simplifying assumptions that often do not account for the details of the prevailing electron energy distribution function (EEDF) and overestimate the contributions of the electron losses to the walls. By direct measurements of the EEDF and careful calculation of contributions of the plasma electrons in low-pressure inductively coupled plasmas, it is shown that the actual losses of kinetic energy of the electrons and ions strongly depend on the EEDF. It is revealed that the overestimates of the total electron/ion energy losses to the walls caused by improper assumptions about the prevailing EEDF and about the ability of the electrons to pass through the repulsive potential of the wall may lead to significant overestimates that are typically in the range between 9 and 32%. These results are particularly important for the development of power-saving strategies for operation of low-temperature, low-pressure gas discharges in diverse applications that require reasonably low power densities.

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“…10 Because ion bombardment energies are determined mainly by the structures and parameters of dual rf-biased sheaths, we must pay attention to the sheath dynamics within a dual frequency configuration. Assuming the current density and electric field to be sinusoidal, Kim et al 8 studied the effect of low frequency current on the electron distribution by using the PIC/MC method. With simplified models, some authors obtained analytical expressions for dual frequency-biased sheaths.…”

Section: Introductionmentioning

confidence: 99%

Simulations of dual rf-biased sheaths and ion energy distributions arriving at a dual rf-biased electrode

2005

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Modeling of the sheath and the energy distribution of ions bombarding rf-biased substrates in high density plasma reactors and comparison to experimental measurements Spatio-temporal characteristics of collisionless dual rf-biased sheaths and ion energy distributions ͑IEDs͒ impinging on a dual rf-biased electrode are studied with a self-consistent one-dimensional hydrodynamic model. The model includes all the time-dependent terms in the ion fluid equations to ensure that it can describe the sheath dynamics over a wide range of frequencies. In addition, an equivalent circuit model is used to self-consistently determine the relationship between the instantaneous sheath thickness and the instantaneous voltage on the dual rf-biased electrode. The numerical results show that, due to dual radiofrequencies being applied to an electrode, the sheath structures and parameters of dual rf-biased sheaths are different from those in the case of single frequency-biased plasma. Multiple peaks appear in the IEDs arriving at the dual rf-biased electrode rather than a bimodal shape as the IEDs are incident onto a single frequency-biased electrode. It is also shown that some parameters such as the bias frequency and power of the lower-frequency source as well as the phase difference between the lower-frequency wave and the higher-frequency wave are crucial for determining the dual rf sheath structure and the shape of IEDs.

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Dual-frequency capacitive discharges: Effect of low-frequency current on electron distribution function

Cited by 34 publications

References 29 publications

Electron heating mechanisms in dual-frequency capacitive discharges

Electron heating mechanisms in dual-frequency capacitive discharges

Electron/ion energy loss to discharge walls revised: A case study in low-temperature, thermally nonequilibrium plasmas

Simulations of dual rf-biased sheaths and ion energy distributions arriving at a dual rf-biased electrode

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