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Sheath Model for Radio-Frequency-Biased, High-Density Plasmas, Valid for all Ω/ΩIota

Published

Author(s)

Mark A. Sobolewski

Abstract

A model is proposed for sheaths in high-density discharges, with radio-frequency (rf) bias applied at frequencies ω comparable to ωi, the ion plasma frequency at the edge of the sheath. The model treats ion dynamics using fluid equations, including all time-dependent terms. Model predictions for current, impedance and power were compared to measurements performed in high-density discharges in argon at 1.33 Pa (10 mTorr at rf frequencies from 0.1 to 10 MHz {omega/omega}i from 0.006 to 1.8) and rf bias voltages from 1 to 200 V. Model predictions were in good agreement with measurements, much better than that obtained by models that neglect time-dependent ion dynamics. In particular, differences of as much as 40-50% between power measurements and the power predicted by previous models are now explained and eliminated. The model also explains why methods of extracting plasma parameters from electrical measurements using previous sheath models may fail, and it suggests more accurate methods of extracting these parameters.
Citation
Physical Review E (Statistical, Nonlinear, and Soft Matter Physics)
Volume
62
Issue
No. 6

Keywords

current, discharge, electrical, model, plasma, power, radio-frequency, sheath, voltage

Citation

Sobolewski, M. (2000), Sheath Model for Radio-Frequency-Biased, High-Density Plasmas, Valid for all &#937;/&#937;<sub>Iota</sub>, Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) (Accessed April 24, 2024)
Created December 1, 2000, Updated June 2, 2021