In this paper we present measurements of the secondary electron emission yield (gamma) of a carbonaceous dust particle material, which was grown in argon diluted acetylene plasmas. One aim was to reach a better understanding of charging and discharging processes of dust particles in complex plasmas due to secondary electron emission and consequently to try to explain the anomalous behavior of electron density observed in afterglows of pulsed rf plasmas. We compared the results of a simple model and of a Monte Carlo simulation to the previously measured time dependence of the electron density in complex plasma afterglow. It was found that the value of the intrinsic secondary electron yield from the carbonaceous dust material is too low to explain the increase of electron density in the afterglow. It is, however, possible that the electrons charging the particles are weakly attached so that they may be released with high efficiency by ion bombardment due to field induced emission or by other mechanisms.

Radio frequency capacitively coupled plasma (RF CCP) sustained at RF frequencies of 27 MHz in an Ar-CF 4 -CF 3 I gas mixture is studied experimentally and theoretically. The RF CCP in Ar-CF 4 -CF 3 I is simulated by using a 1D hybrid particle-in-cell-fluid numerical model. We pay special attention to the changes in plasma structure and fluxes to the electrode, negative ion and neutral radical production with admixture of CF 3 I in Ar-CF 4 plasma. With CF 3 I admixture the plasma becomes strongly electronegative as a result of the high electron attachment rate to the CF 3 I molecule. The atomic fluorine density becomes extremely low with addition of CF 3 I molecules due to the large volume loss in the reaction CF 3 I + F → CF 3 + IF. Optical emission spectrometry data on CF 2 emission at the wavelength of 250 nm indicate the essential sources of CF 2 in CF 3 I-containing plasma in the studied conditions, although direct dissociation channels for the CF 3 I molecule with CF 2 production have not been studied. Evaluation of CF 2 density in Ar-CF 4 -CF 3 I plasma was first carried out on the basis of the actinometry technique and numerical simulation. The possible mechanism of ultra-low-k film damage in the studied conditions is also discussed.

An improvement to the RF-biased planar Langmuir probe technique proposed by Braithwaite et al (1996 Plasma Sources Sci. Technol. 5 67) is demonstrated, and applied to the case of an industrial CCP reactor. Compared with the RF-biased probe, the new technique uses dc pulses instead of RF bursts, which provides similar results but with simpler electronics. The ion fluxes determined by both techniques are compared under the same O 2 /Ar plasma conditions using available literature data for the RF-biased case. The data show not only the same trends but very close absolute values of ion fluxes for all studied plasma conditions after correcting for the chamber-area difference. Furthermore, the new technique has the additional benefit of providing information on the 'electron transition region' of the I -V curve, as well as allowing the resistance and capacitance of films deposited on the probe to be determined. Finally, both experimental data and numerical simulations of the I -V characteristics and the film parameters are presented for different oxidizing plasmas.

We describe measurements of plasma properties of pulsed, low pressure, capacitively coupled discharges operated in argon. The research aims to determine the effect of modulating the radiofrequency power during the discharge part of the pulse cycle. Measurements of local electron density and optical emission were made in capacitively-coupled rf discharges generated in a Gaseous Electronics Conference (GEC) reference reactor. Gas pressure was in the range 7-70 Pa, rf power in the range 1-100 W and pulse durations in the range of 10 µs-100 ms. The results indicate that the ignition and afterglow decay processes in pulsed discharges can be controlled by modulating the shape of applied radiofrequency pulse.