Abstract. Ion energy distribution functions (IEDFs) near a source exit of a magnetically expanding argon plasma using only permanent magnets (PMs) are measured by a combination of a retarding field energy analyzer and a pulsed probe method for three types of magnetic-field configurations and various operating gas pressures, where the magnetic-field strength in the source tube is increased up to 270 Gauss by adding the number of the PM layers. The 13.56 MHz rf power for plasma production is maintained at 250 W. The IEDFs show the existence of an accelerated group of ions. It is found that the energy of the accelerated ions increases when the magnetic-field strength is increased, but saturates at seven times the electron temperature at argon pressures of 0.6-1.6 mTorr. Our results show that the maximum velocity of the accelerated ions is found to be 14 km/sec with a Mach number of 3.8.2

Abstract-Plasma potential structures and ion-energy distribution functions are measured in a magnetically expanding radiofrequency plasma using permanent magnets (PMs) and in a geometrically expanding one, where the radio-frequency power and the argon-gas pressure are maintained at 250 W and 1 mtorr, respectively. In the magnetically expanding plasma, a rapid potential drop like a double-layer structure and a subsequent supersonic ion beam are detected by retarding field energy analyzers. On the other hand, a plasma potential structure following Boltzmann relation accelerates the ions in the geometrically expanding plasma. The comparison between the results in both cases indicates that the existence of the PMs is effective for the generation of the high-speed ion beam, where the mach number of the ion beam is increased to about 3.5 by using the PMs compared with the mach number of 2.3 in the operation mode of the geometrically expanding plasma.Index Terms-Double layer (DL), expanding plasma, ion acceleration, permanent magnets (PMs), plasma potential structures.

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A self-consistent two dimensional numerical fluid model of rf plasmas under conditions close to those of the experiments for observing particle growth in silane rf plasmas has been developed. The geometry of the discharge chamber and the electrodes used in the model is cylindrically symmetric: two cylinders for the electrodes are surrounded by the grounded chamber. The rf plasmas are in SiH4(10%)/Ar(90%) at a pressure of 100 mTorr at 6.5 MHz. The results from the model, including the rf plasma structures and the generation rates for radicals, SiH, SiH2 and SiH3, are presented. Effects of the applied rf voltage and the secondary electron emission coefficient on the generation rates of the radicals are discussed.

Effects of gas flow on rf plasmas between parallel plates under plasma processing conditions are investigated using a Monte Carlo simulation (MCS) and a fluid model calculation. It has shown that the gas flow changes the ion density distribution in the bulk region of the rf plasma where the velocity of gas flow is faster than that of the ion diffusion motion. Comparison of the results of the MCS with those of the fluid model calculation has shown that the fluid model in which the velocity of gas flow is added to the drift and diffusion motion may be valid at a pressure above 1 Torr. Using the fluid model and Poisson's equation, self-consistent calculations of the argon and silane rf plasmas have been carried out. This indicates that the plasma structure including negative ions is sensitively changed by the gas flow.