Heating by RF sheaths
- Univ. of California, Berkeley, CA (United States)
Low pressure, capacitively coupled rf discharges used for materials processing are typically operated at 1-100 mTorr with 50-1000 V applied at 13.56 MHz in a parallel plate chamber. Under these conditions, electrons are stochastically heated. Previous derivations of stochastic heating rates have assumed that the sheath motion is slow compared to the electron thermal velocity, and that the electrons are maxwellian. Using PDP1, a 1d3v PIC simulation code, the authors find that these assumptions are not valid for many experimental parameter ranges. In particular, the electron distribution is two temperature, is warmer at the sheath edge than in the body of the plasma, and displays drifts which are of the order of the sheath velocity. Incorporating these changed assumptions into the existing theory, the authors show that the stochastic power delivered by the sheaths to the electrons is greatly enhanced, and that the scaling of the density and sheath thickness with r.f. driving voltage is increased. They compare these scalings to recently published experimental results.
- OSTI ID:
- 127906
- Report Number(s):
- CONF-920376--
- Journal Information:
- Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 9 Vol. 37; ISSN BAPSA6; ISSN 0003-0503
- Country of Publication:
- United States
- Language:
- English
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