Generation of Uniform Large-Area VHF Plasmas by Launching a Traveling Wave

Chen, Hsin‐Liang; Tu, Yen-Cheng; Hsieh, Cheng-Chang; Ai, Chi-Fong; Tsai, Wen-Fa; Leou, Keh-Chyang

doi:10.1002/ppap.201300101

Cited by 3 publications

(1 citation statement)

References 20 publications

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“…Both experimental [19][20][21] and numerical [22][23][24] research indicated that by varying the phase difference between the two sources applied to the top and bottom electrodes, i.e., the so-called phase-shift control, the plasma currents redistributed and therefore the plasma uniformity could be optimized. Moreover, Chen et al pointed out that the plasma nonuniformity decreased significantly by launching a traveling wave, which was generated by the superposition of two standing waves with the same amplitude and out of phase by 90 • in space and time [25][26][27]. Bera et al introduced the electric potential and the magnetic vector potential to calculate the ES field and the EM field, respectively, and they presented different electron density distributions with various combinations of powers at 60 MHz and 180 MHz [28].…”

Section: Introductionmentioning

confidence: 99%

How to address the issue of uniformity in large area capacitively coupled plasmas? A modeling investigation

Zhang

Wang

2020

Plasma Sources Sci. Technol.

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Recently, the electrical asymmetry effect (EAE) has been proven effective not only in separate control of the ion energy and ion flux, but also in modulation of the plasma radial uniformity. Since no major change in reactor constructions is required, this method is promising and of significant importance in the plasma industry. In this work, a two-dimensional electromagnetic fluid model is employed to investigate the influence of the EAE on the plasma density distribution under various voltages (i.e., the peak-to-peak voltage V 0 equals to 33 V, 56 V and 100 V) and pressures (i.e., 50 mTorr, 200 mTorr and 750 mTorr), in H 2 capacitively coupled plasma (CCP) discharges sustained by multiple consecutive harmonics. The results indicate that at V 0 = 33 V or 750 mTorr, the plasma density is characterized by a broad maximum at the radial center, and the effectiveness of the EAE on the modulation of the plasma radial uniformity is limited. When V 0 becomes higher, the plasma distribution varies obviously by adjusting the phase shift of the fundamental frequency θ 1 . For instance, when θ 1 increases from 0 to 2π at V 0 = 56 V, the plasma density shifts from uniform over center-high to uniform. Moreover, at V 0 = 100 V, the best uniformity is observed at θ 1 = π. When the pressure decreases to 50 mTorr, although the uniformity varies significantly with θ 1 , the plasma density stays low, which may not be welcomed in the plasma processing. Different influences of the EAE on the plasma radial uniformity can be understood by examining the electron heating induced by the sheath expansion and the electric field reversal under various discharge conditions. The results obtained in this work could help us to have a better understanding of the EAE on the plasma radial uniformity, which would be useful to improve the plasma processing in large area CCP reactors.

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Section: Introductionmentioning

confidence: 99%

How to address the issue of uniformity in large area capacitively coupled plasmas? A modeling investigation

Zhang

Wang

2020

Plasma Sources Sci. Technol.

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Improving discharge uniformity of industrial-scale very high frequency plasma sources by launching a traveling wave

Chen

Hsieh

et al. 2016

Current Applied Physics

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Generation of uniform large-area very high frequency plasmas by launching two specific standing waves simultaneously

Chen

Hsieh

et al. 2014

Journal of Applied Physics

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With the characteristics of higher electron density and lower ion bombardment energy, large-area VHF (very high frequency) plasma enhanced chemical vapor deposition has become an essential manufacturing equipment to improve the production throughput and efficiency of thin film silicon solar cell. However, the combination of high frequency and large electrodes leads to the so-called standing wave effect causing a serious problem for the deposition uniformity of silicon thin film. In order to address this issue, a technique based on the idea of simultaneously launching two standing waves that possess similar amplitudes and are out of phase by 90° in time and space is proposed in this study. A linear plasma reactor with discharge length of 54 cm is tested with two different frequencies including 60 and 80 MHz. The experimental results show that the proposed technique could effectively improve the non-uniformity of VHF plasmas from >±60% when only one standing wave is applied to <±10% once two specific standing waves are launched at the same time. Moreover, in terms of the reactor configuration adopted in this study, in which the standing wave effect along the much shorter dimension can be ignored, the proposed technique is applicable to different frequencies without the need to alter the number and arrangement of power feeding points.

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Generation of Uniform Large-Area VHF Plasmas by Launching a Traveling Wave

Cited by 3 publications

References 20 publications

How to address the issue of uniformity in large area capacitively coupled plasmas? A modeling investigation

How to address the issue of uniformity in large area capacitively coupled plasmas? A modeling investigation

Improving discharge uniformity of industrial-scale very high frequency plasma sources by launching a traveling wave

Generation of uniform large-area very high frequency plasmas by launching two specific standing waves simultaneously

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