中国物理B ›› 2007, Vol. 16 ›› Issue (3): 758-765.doi: 10.1088/1009-1963/16/3/033

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Review of relaxation oscillations in plasma processing discharges

M.A.Lieberman1, SungjinKim1, 周筑文2   

  1. (1)Department of Electrical Engineering and Computer Sciences- 1770 University of California,Berkeley, CA 94720, U.S.A.; (2)Department of Physics, Guizhou Educational College, Guiyang 550003, China
  • 收稿日期:2006-05-28 修回日期:2006-09-12 出版日期:2007-03-20 发布日期:2007-03-20
  • 基金资助:
    Project supported by the National Science Foundation of USA (Grant No ECS-0139956).

Review of relaxation oscillations in plasma processing discharges

Zhou Zhu-Wen(周筑文)a) † , M. A. Liebermanb), and Sungjin Kimb)   

  1. a Department of Physics, Guizhou Educational College, Guiyang 550003, China; b Department of Electrical Engineering and Computer Sciences- 1770 University of California, Berkeley, CA 94720, U.S.A.
  • Received:2006-05-28 Revised:2006-09-12 Online:2007-03-20 Published:2007-03-20
  • Supported by:
    Project supported by the National Science Foundation of USA (Grant No ECS-0139956).

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摘要： Relaxation oscillations due to plasma instabilities at frequencies ranging from a few Hz to tens of kHz have been observed in various types of plasma processing discharges. Relaxation oscillations have been observed in electropositive capacitive discharges between a powered anode and a metallic chamber whose periphery is grounded through a slot with dielectric spacers. The oscillations of time-varying optical emission from the main discharge chamber show, for example, a high-frequency (\sim 40~kHz) relaxation oscillation at 13.33Pa, with an absorbed power being nearly the peripheral breakdown power, and a low-frequency ( \sim 3 Hz) oscillation, with an even higher absorbed power. The high-frequency oscillation is found to ignite plasma in the slot, but usually not in the peripheral chamber. The kilohertz oscillations are modelled using an electromagnetic model of the slot impedance, coupled to a circuit analysis of the system including the matching network. The model results are in general agreement with the experimental observations, and indicate a variety of behaviours dependent on the matching conditions. In low-pressure inductive discharges, oscillations appear in the transition between low-density capacitively driven and high-density inductively driven discharges when attaching gases such as SF6 and Ar/SF6 mixtures are used. Oscillations of charged particles, plasma potential, and light, at frequencies ranging from a few Hz to tens of kHz, are seen for gas pressures between 0.133 Pa and 13.33 Pa and discharge powers in a range of 75--1200 W. The region of instability increases as the plasma becomes more electronegative, and the frequency of plasma oscillation increases as the power, pressure, and gas flow rate increase. A volume-averaged (global) model of the kilohertz instability has been developed; the results obtained from the model agree well with the experimental observations.

关键词: relaxation oscillation, capacitive discharges, inductive discharges, plasma instability

Abstract: Relaxation oscillations due to plasma instabilities at frequencies ranging from a few Hz to tens of kHz have been observed in various types of plasma processing discharges. Relaxation oscillations have been observed in electropositive capacitive discharges between a powered anode and a metallic chamber whose periphery is grounded through a slot with dielectric spacers. The oscillations of time-varying optical emission from the main discharge chamber show, for example, a high-frequency ($\sim$  40 kHz) relaxation oscillation at 13.33Pa, with an absorbed power being nearly the peripheral breakdown power, and a low-frequency ($\sim$  3 Hz) oscillation, with an even higher absorbed power. The high-frequency oscillation is found to ignite plasma in the slot, but usually not in the peripheral chamber. The kilohertz oscillations are modelled using an electromagnetic model of the slot impedance, coupled to a circuit analysis of the system including the matching network. The model results are in general agreement with the experimental observations, and indicate a variety of behaviours dependent on the matching conditions. In low-pressure inductive discharges, oscillations appear in the transition between low-density capacitively driven and high-density inductively driven discharges when attaching gases such as SF6 and Ar/SF6 mixtures are used. Oscillations of charged particles, plasma potential, and light, at frequencies ranging from a few Hz to tens of kHz, are seen for gas pressures between 0.133 Pa and 13.33 Pa and discharge powers in a range of 75--1200 W. The region of instability increases as the plasma becomes more electronegative, and the frequency of plasma oscillation increases as the power, pressure, and gas flow rate increase. A volume-averaged (global) model of the kilohertz instability has been developed; the results obtained from the model agree well with the experimental observations.

Key words: relaxation oscillation, capacitive discharges, inductive discharges, plasma instability

中图分类号:  (Electrostatic waves and oscillations (e.g., ion-acoustic waves))

  • 52.35.Fp
52.80.-s (Electric discharges)