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Particle simulation of a magnetized dual-frequency capacitively coupled plasma
Computer Physics Communications 177 (2007) 125 www.elsevier.com/locate/cpc
Particle simulation of a magnetized dual-frequency capacitively coupled plasma Daeho Kim, Hyonu Chang, Chang-Mo Ryu ∗ Department of Physics, POSTECH, Pohang 790-784, Republic of Korea Available online 6 March 2007
The latest trends in the development of the capacitively coupled plasma (CCP) comprise utilization of multi-frequencies to independently control plasma parameters [1] and magnetic enhancement of the system to increase the plasma density [2]. The purpose of this paper is to investigate the effect of a transverse magnetic field in a dual-frequency capacitively coupled plasma (DF-CCP) using 1-D PIC/MCC simulation (XPDC1 code), following these recent trends. Two radio-frequency (RF) voltage sources with frequencies of 27 (outer) and 2 (inner) MHz were applied to the coaxial cylindrical electrodes. Both RF amplitudes were fixed at 720 V. Argon gas is used at a pressure of 40 mTorr. The secondary electron emission coefficient is 0.2. The overall behaviors of the plasma such as the electric properties and the ion energy distributions, with respect to the variation of the magnetic field, are found to be in a good agreement with those observed in a 2-D fluid model for a different discharge system [3]. However, in our case, plasma density and 1/(sheath thickness) is found to increase with an increasing magnetic field. Fig. 1 demonstrates that the high energy tail of the ions, which in general increases with the voltage increase, is drastically extended for B = 50 G. The time averaged sheath potential is found to be the largest for this magnetic field. When the magnetic field is increased further to B = 125 G, the high energy ion tail is reduced significantly. The efficiency of ionization seems to be affected very much by the magnetic field. To summarize, it is found that a proper magnetic field can enhance the independent controllability of low- and highfrequency sources without reciprocal diminishment.
* Corresponding author.
E-mail address: [email protected] (C.-M. Ryu). 0010-4655/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.cpc.2007.02.101
Fig. 1. Ion energy distribution functions for various low-frequency voltages, 0, 720 and 1440 V, and magnetic fields, 0, 50, and 125 G.
References [1] H.H. Goto, H.D. Lowe, T. Ohmi, J. Vac. Sci. Technol. A 10 (1992) 3048. [2] M.A. Lieberman, A.J. Lichtenberg, S.E. Saves, IEEE Trans. Plasma Sci. 19 (1991) 189. [3] M.J. Kushner, J. Appl. Phys. 94 (2003) 1436.
Particle simulation of a magnetized dual-frequency capacitively coupled plasma Daeho Kim, Hyonu Chang, Chang-Mo Ryu ∗ Department of Physics, POSTECH, Pohang 790-784, Republic of Korea Available online 6 March 2007
The latest trends in the development of the capacitively coupled plasma (CCP) comprise utilization of multi-frequencies to independently control plasma parameters [1] and magnetic enhancement of the system to increase the plasma density [2]. The purpose of this paper is to investigate the effect of a transverse magnetic field in a dual-frequency capacitively coupled plasma (DF-CCP) using 1-D PIC/MCC simulation (XPDC1 code), following these recent trends. Two radio-frequency (RF) voltage sources with frequencies of 27 (outer) and 2 (inner) MHz were applied to the coaxial cylindrical electrodes. Both RF amplitudes were fixed at 720 V. Argon gas is used at a pressure of 40 mTorr. The secondary electron emission coefficient is 0.2. The overall behaviors of the plasma such as the electric properties and the ion energy distributions, with respect to the variation of the magnetic field, are found to be in a good agreement with those observed in a 2-D fluid model for a different discharge system [3]. However, in our case, plasma density and 1/(sheath thickness) is found to increase with an increasing magnetic field. Fig. 1 demonstrates that the high energy tail of the ions, which in general increases with the voltage increase, is drastically extended for B = 50 G. The time averaged sheath potential is found to be the largest for this magnetic field. When the magnetic field is increased further to B = 125 G, the high energy ion tail is reduced significantly. The efficiency of ionization seems to be affected very much by the magnetic field. To summarize, it is found that a proper magnetic field can enhance the independent controllability of low- and highfrequency sources without reciprocal diminishment.
* Corresponding author.
E-mail address: [email protected] (C.-M. Ryu). 0010-4655/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.cpc.2007.02.101
Fig. 1. Ion energy distribution functions for various low-frequency voltages, 0, 720 and 1440 V, and magnetic fields, 0, 50, and 125 G.
References [1] H.H. Goto, H.D. Lowe, T. Ohmi, J. Vac. Sci. Technol. A 10 (1992) 3048. [2] M.A. Lieberman, A.J. Lichtenberg, S.E. Saves, IEEE Trans. Plasma Sci. 19 (1991) 189. [3] M.J. Kushner, J. Appl. Phys. 94 (2003) 1436.