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Title: Mode transitions and hysteresis in inductively coupled plasmas

Abstract

Optical emission spectroscopy as a noninvasive plasma diagnostic was employed to study mode transitions and hysteresis in an inductively coupled plasma in Ar and Ar/N{sub 2} mixtures. Using selected Ar lines, basic plasma parameters, relevant to the analysis of the mode transitions, were evaluated. Small changes of the electron energy distribution function in the vicinity of the mode transition were detected. The role of metastable Ar atoms in mode transitions and in a hysteresis was clarified. Enhanced production of metastables in the hysteresis region as well as faster transitions in plasmas with higher influence of metastables were observed.

Authors:
; ; ; ; ;  [1];  [2];  [3]
  1. Center for Semiconductor Components, Universidade Estadual de Campinas--UNICAMP, P.O. Box 6061, Campinas SP 13083-870 (Brazil)
  2. (Russian Federation)
  3. (Brazil)
Publication Date:
OSTI Identifier:
20982792
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 7; Other Information: DOI: 10.1063/1.2715845; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ARGON; ELECTRONS; EMISSION SPECTROSCOPY; ENERGY SPECTRA; HYSTERESIS; MIXTURES; NITROGEN; PLASMA; PLASMA DIAGNOSTICS; PLASMA INSTABILITY

Citation Formats

Daltrini, A. M., Moshkalev, S. A., Monteiro, M. J. R., Besseler, E., Kostryukov, A., Machida, M., Plasma Physics Department, St. Petersburg Polytechnical University, St. Petersburg 194021, and Institute of Physics 'Gleb Wataghin', Universidade Estadual de Campinas--UNICAMP, P.O. Box 6101, Campinas SP 13083-970. Mode transitions and hysteresis in inductively coupled plasmas. United States: N. p., 2007. Web. doi:10.1063/1.2715845.
Daltrini, A. M., Moshkalev, S. A., Monteiro, M. J. R., Besseler, E., Kostryukov, A., Machida, M., Plasma Physics Department, St. Petersburg Polytechnical University, St. Petersburg 194021, & Institute of Physics 'Gleb Wataghin', Universidade Estadual de Campinas--UNICAMP, P.O. Box 6101, Campinas SP 13083-970. Mode transitions and hysteresis in inductively coupled plasmas. United States. doi:10.1063/1.2715845.
Daltrini, A. M., Moshkalev, S. A., Monteiro, M. J. R., Besseler, E., Kostryukov, A., Machida, M., Plasma Physics Department, St. Petersburg Polytechnical University, St. Petersburg 194021, and Institute of Physics 'Gleb Wataghin', Universidade Estadual de Campinas--UNICAMP, P.O. Box 6101, Campinas SP 13083-970. Sun . "Mode transitions and hysteresis in inductively coupled plasmas". United States. doi:10.1063/1.2715845.
@article{osti_20982792,
title = {Mode transitions and hysteresis in inductively coupled plasmas},
author = {Daltrini, A. M. and Moshkalev, S. A. and Monteiro, M. J. R. and Besseler, E. and Kostryukov, A. and Machida, M. and Plasma Physics Department, St. Petersburg Polytechnical University, St. Petersburg 194021 and Institute of Physics 'Gleb Wataghin', Universidade Estadual de Campinas--UNICAMP, P.O. Box 6101, Campinas SP 13083-970},
abstractNote = {Optical emission spectroscopy as a noninvasive plasma diagnostic was employed to study mode transitions and hysteresis in an inductively coupled plasma in Ar and Ar/N{sub 2} mixtures. Using selected Ar lines, basic plasma parameters, relevant to the analysis of the mode transitions, were evaluated. Small changes of the electron energy distribution function in the vicinity of the mode transition were detected. The role of metastable Ar atoms in mode transitions and in a hysteresis was clarified. Enhanced production of metastables in the hysteresis region as well as faster transitions in plasmas with higher influence of metastables were observed.},
doi = {10.1063/1.2715845},
journal = {Journal of Applied Physics},
number = 7,
volume = 101,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
}
  • An experimental investigation of the hysteresis during the E (capacitive coupling) and H mode (inductive coupling) transitions at various matching situation in argon inductively coupled plasma is reported. At high pressure, the results show two hysteresis loops involved the plasma density, applied power, and forward power, as well as the electrical parameters in the discharge circuit, when the series capacitance is cycled. The measured electron density versus applied power shows that the hysteresis loop shrinks with the decrease of the matching capacitance, and the same trend is discovered on the input current, voltage, and phase angle. In addition, for themore » case of small capacitance, the current (or voltage) jumps to a low value when the discharge passes through the E to H mode transition regime. Contrarily, for the case of large capacitance, the current jumps to a high value while the voltage is almost constant. The evolution characteristics of the plasma and circuit parameters observed imply that the nonlinear behavior of the matching situation may be one of the determined factors for hysteresis.« less
  • Transitions between the two discharge modes in a low-frequency ({approx}460 kHz) inductively coupled plasma sustained by an internal oscillating radio frequency (rf) current sheet are studied. The unidirectional rf current sheet is generated by an internal antenna comprising two orthogonal sets of synphased rf currents driven in alternately reconnected copper litz wires. It is shown that in the low-to-intermediate pressure range the plasma source can be operated in the electrostatic (E) and electromagnetic (H) discharge modes. The brightness of the E-mode argon plasma glow is found remarkably higher than in inductively coupled plasmas with external flat spiral 'pancake' coils. Themore » cyclic variations of the input rf power result in pronounced hysteretic variations of the optical emission intensity and main circuit parameters of the plasma source. Under certain conditions, it appears possible to achieve a spontaneous E{yields}H transition ('self-transition'). The observed phenomenon can be attributed to the thermal drift of the plasma parameters due to the overheating of the working gas. The discharge destabilizing factors due to the gas heating and step-wise ionization are also discussed.« less
  • Space and phase resolved optical emission spectroscopic measurements reveal that in certain parameter regimes, inductively coupled radio-frequency driven plasmas exhibit three distinct operation modes. At low powers, the plasma operates as an alpha-mode capacitively coupled plasma driven through the dynamics of the plasma boundary sheath potential in front of the antenna. At high powers, the plasma operates in inductive mode sustained through induced electric fields due to the time varying currents and associated magnetic fields from the antenna. At intermediate powers, close to the often observed capacitive to inductive (E-H) transition regime, energetic electron avalanches are identified to play amore » significant role in plasma sustainment, similar to gamma-mode capacitively coupled plasmas. These energetic electrons traverse the whole plasma gap, potentially influencing plasma surface interactions as exploited in technological applications.« less
  • It is well known experimentally that the circuit matching network plays an important role in the mode transition behavior of inductively coupled plasmas. To date, however, there have been no reports of numerical models being used to study the role of the matching circuit in the transition process. In this paper, a new two-dimensional self-consistent fluid model that couples the components of an equivalent circuit module is developed to investigate the effects of the equivalent circuit on the mode transition characteristics of an inductively coupled, hydrogen plasma. The equivalent circuit consists of a current source, impedance matching network, reactor impedance,more » and plasma transferred impedance. The nonlinear coupling of the external circuit with the internal plasma is investigated by adjusting the matching capacitance at a fixed input current. The electron density and temperature as well as the electromagnetic fields all change suddenly, and the E to H mode transition occurs abruptly at a certain matching capacitance as the impedance matching of the external circuit is varied. We also analyze the fields and the plasma characteristics during the transition process, especially for the case of the capacitive E mode.« less
  • Plasma densities, E to H and H to E transition coil currents, and electron energy distribution functions (EEDFs) are measured at various argon pressures in an inductively coupled plasma. The measured plasma density versus coil current shows that the hysteresis during the E-H transition is clearly observed only when the pressure is sufficiently high. At low gas pressures the hysteresis is not obvious. The measured EEDFs show that when the hysteresis is obvious (high pressures), electrons whose energy is not sufficient for excitation or ionization of the ground state atom are strongly depleted in the H mode. This depletion maymore » be caused by multistep ionization. However, for the case where the hysteresis is not obvious (low pressures), the depletion due to multistep ionization is also not present. These experimental results show that the multistep ionization is a dominant factor in the E-H transition hysteresis.« less