Optical and mass spectrometric investigations of ions and neutral species inSF6radio-frequency discharges

Modes of rf capacitive discharge in low-pressure sulfur hexafluoride

“…The intensities of SiF + 3 and S + 2 peaks in α-mode decrease weakly, but after the transition to δ-mode the intensities of these peaks within the same range of rf voltage are 10 and 3 times larger, respectively. Let us evaluate the dissociation degree of SF 6 molecules from formulae [11]: where I 0 and I pl are the intensities of the SF + 5 without and with the rf discharge, respectively. Here D u denotes the upper limit of the dissociation degree of SF 6 molecules and it is found under the assumption that the total gas number density does not increase with dissociation.…”

“…It is difficult to understand what occurs with a CVC on varying the pressure; what are the modes of discharge existence under various conditions. In our opinion, the authors of [8,11] made erroneous conclusions on the burning modes of rf discharge in SF 6 . Moreover, there are discrepancies in evaluating the dissociation degree of SF 6 molecules in the discharge: paper [11] reports the values up to 80%, whereas the authors of [12] made a statement about a low dissociation degree, not exceeding 6%.…”

“…An impression may be created that the rf discharge in SF 6 was already studied in such detail that there is no necessity of further research. However, only papers [8,11] deal with the discharge burning modes and the transition between them. The authors of papers [8,11] made an assumption that the presence of a sharp increase of the discharge current with rf voltage growing was due to significant increase of ionization at the double layer in the near-electrode sheaths, and, as a consequence, to the increase of the rf electric field in the discharge volume.…”

“…0022-3727/07/226989+11$30.00 © 2007 IOP Publishing Ltd Printed in the UK Foest et al [11] investigated rf discharge in pure SF 6 using GEC reference cell. They obtained that the plasma becomes more resistive as pressure increased.…”

“…The authors of papers [8,11] made an assumption that the presence of a sharp increase of the discharge current with rf voltage growing was due to significant increase of ionization at the double layer in the near-electrode sheaths, and, as a consequence, to the increase of the rf electric field in the discharge volume. At the same time, the authors of [8,11] present only a limited set of currentvoltage characteristics (CVCs) (the paper [8] gives the CVCs for the SF 6 pressure values of 0.1, 0.5 and 1 Torr, and the authors of [11] limited themselves only to a single CVC for the SF 6 pressure value of 0.1 Torr). It is difficult to understand what occurs with a CVC on varying the pressure; what are the modes of discharge existence under various conditions.…”