Phase-shift effect in capacitively coupled plasmas with two radio frequency or very high frequency sources

Xu, Xiaohui; Zhao, Shugao; Zhang, Yuru; Wang, You‐Nian

doi:10.1063/1.3475376

Cited by 22 publications

(18 citation statements)

References 27 publications

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“…The uniformity was gradually improved upon increasing the phase shift between 0 and p. These observations are quite consistent with the simulation results in Refs. [49][50][51][52][53]. Note that the experiments in Ref.…”

Section: Phase Shift Controlmentioning

confidence: 93%

“…At u ¼ p, i.e., out of phase condition, a more uniform plasma density distribution can be achieved. Xu et al 50 compared the phase shift effect on the uniformity between an electrostatic and an EM case by using a similar 2D fluid model, including the full set of Maxwell equations; see Fig. 16 for an illustration of the electrode configuration.…”

Section: Phase Shift Controlmentioning

confidence: 99%

See 1 more Smart Citation

Electromagnetic effects in high-frequency large-area capacitive discharges: A review

Liu¹,

Zhang²,

Bogaerts³

et al. 2015

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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In traditional capacitively coupled plasmas, the discharge can be described by an electrostatic model, in which the Poisson equation is employed to determine the electrostatic electric field. However, current plasma reactors are much larger and driven at a much higher frequency. If the excitation wavelength k in the plasma becomes comparable to the electrode radius, and the plasma skin depth d becomes comparable to the electrode spacing, the electromagnetic (EM) effects will become significant and compromise the plasma uniformity. In this regime, capacitive discharges have to be described by an EM model, i.e., the full set of Maxwell's equations should be solved to address the EM effects. This paper gives an overview of the theory, simulation and experiments that have recently been carried out to understand these effects, which cause major uniformity problems in plasma processing for microelectronics and flat panel display industries. Furthermore, some methods for improving the plasma uniformity are also described and compared.

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Section: Phase Shift Controlmentioning

confidence: 93%

Section: Phase Shift Controlmentioning

confidence: 99%

Electromagnetic effects in high-frequency large-area capacitive discharges: A review

Liu¹,

Zhang²,

Bogaerts³

et al. 2015

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

Self Cite

View full text Add to dashboard Cite

show abstract

“…In recent years, several theoretical studies [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and experimental research [22][23][24][25][26][27][28][29][30] have been published on the plasma characteristics in a CCP sustained by VHF sources. Lieberman et al 6 first employed a uniform slab model to investigate the standing-wave and skin effects in VHF discharges.…”

Section: Introductionmentioning

confidence: 99%

“…Besides, considerable effort has also been made on studying the discharge mechanisms with dual frequency excitation in the VHF regime. [15][16][17][18][19][20][21] Yang and Kushner 19-21 utilized a full-wave Maxwell solver, and studied the properties of plasmas sustained in Ar and Ar/ CF 4 at different discharge conditions.…”

Section: Introductionmentioning

confidence: 99%

Comparison of electrostatic and electromagnetic simulations for very high frequency plasmas

Zhang

Zhao

et al. 2010

Physics of Plasmas

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A two-dimensional self-consistent fluid model combined with the full set of Maxwell equations is developed to investigate an argon capacitively coupled plasma, focusing on the electromagnetic effects on the discharge characteristics at various discharge conditions. The results indicate that there exist distinct differences in plasma characteristics calculated with the so-called electrostatic model (i.e., without taking into account the electromagnetic effects) and the electromagnetic model (which includes the electromagnetic effects), especially at very high frequencies. Indeed, when the excitation source is in the high frequency regime and the electromagnetic effects are taken into account, the plasma density increases significantly and meanwhile the ionization rate evolves to a very different distribution when the electromagnetic effects are dominant. Furthermore, the dependence of the plasma characteristics on the voltage and pressure is also investigated, at constant frequency. It is observed that when the voltage is low, the difference between these two models becomes more obvious than at higher voltages. As the pressure increases, the plasma density profiles obtained from the electromagnetic model smoothly shift from edge-peaked over uniform to a broad maximum in the center. In addition, the edge effect becomes less pronounced with increasing frequency and pressure, and the skin effect rather than the standing-wave effect becomes dominant when the voltage is high.

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“…[4,5] Furthermore, Xu et al studied the phaseshift effect on the CCP discharge, especially on the radial uniformity of the plasma density and the ion flux. [6] They found that the edge effect could be controlled by adjusting the phase difference.…”

Section: Introductionmentioning

confidence: 99%

Influence of dielectric materials on uniformity of large-area capacitively coupled plasmas for N ₂ /Ar discharges

Liang¹,

Zhang²,

Wang³

2016

Chinese Phys. B

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The effect of the dielectric ring on the plasma radial uniformity is numerically investigated in the practical 450-mm capacitively coupled plasma reactor by a two-dimensional self-consistent fluid model. The simulations were performed for N 2 /Ar discharges at the pressure of 300 Pa, and the frequency of 13.56 MHz. In the practical plasma treatment process, the wafer is always surrounded by a dielectric ring, which is less studied. In this paper, the plasma characteristics are systematically investigated by changing the properties of the dielectric ring, i.e., the relative permittivity, the thickness and the length. The results indicate that the plasma parameters strongly depend on the properties of the dielectric ring. As the ratio of the thickness to the relative permittivity of the dielectric ring increases, the electric field at the wafer edge becomes weaker due to the stronger surface charging effect. This gives rise to the lower N + 2 ion density, flux and N atom density at the wafer edge. Thus the homogeneous plasma density is obtained by selecting optimal dielectric ring relative permittivity and thickness. In addition, we also find that the length of the dielectric ring should be as short as possible to avoid the discontinuity of the dielectric materials, and thus obtain the large area uniform plasma.

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Phase-shift effect in capacitively coupled plasmas with two radio frequency or very high frequency sources

Cited by 22 publications

References 27 publications

Electromagnetic effects in high-frequency large-area capacitive discharges: A review

Electromagnetic effects in high-frequency large-area capacitive discharges: A review

Comparison of electrostatic and electromagnetic simulations for very high frequency plasmas

Influence of dielectric materials on uniformity of large-area capacitively coupled plasmas for N ₂ /Ar discharges

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Phase-shift effect in capacitively coupled plasmas with two radio frequency or very high frequency sources

Cited by 22 publications

References 27 publications

Electromagnetic effects in high-frequency large-area capacitive discharges: A review

Electromagnetic effects in high-frequency large-area capacitive discharges: A review

Comparison of electrostatic and electromagnetic simulations for very high frequency plasmas

Influence of dielectric materials on uniformity of large-area capacitively coupled plasmas for N 2 /Ar discharges

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Influence of dielectric materials on uniformity of large-area capacitively coupled plasmas for N ₂ /Ar discharges