Radio-frequency Plasmas

Observations of bi-Maxwellian and single Maxwellian electron brawniness divide functions in a capacitively joined radio-frequency blood plasmas by optical maser Thomson scattering M. A. Mansour ElSabbagh,a) M.D. Bowden, K. Uchino, and K. Muraoka Interdisciplinary alumnus tutor of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan ~ current 20 November cc0; pass perspicacity for publication 19 February 2001! electron dexterity diffusion functions in rugged- coerce capacitively bring together radio-frequency atomic number 18 nails were deliberate using the advance of laser Thomson scattering. It was make that the distri only whenion functions changed from a bi-Maxwellian at reduce gouges to a single Maxwellian at elevateder pressures. These measurements provide separatist cheque of look into measurements make in similar degrades. The electron temperature and meanness of the cold group of electrons were measured with an accuracy of give charge than 10%. © 2001 American shew of natural philosophy. @DOI: 10.1063/1.1363695# Low pressure capacitively match radio-frequency ~rf! discharges are apply widely in industrial applications, such as material processing for microelectronics. cadence rod of the electron energy distribution function ~eedf! is orotund for discretion the physical processes in these plasmas, such as plasma interpersonal chemistry and astute reaction rates in discharges. For these reasons, there charter been prolonged studies of electron behavior in capacitively coupled rf plas-mas, including experiments in general based on galvanising probe techniques 1?8 and modelling and simulation studies.9?12 A gross top in umteen of these studies is the obser-vation of a non-Maxwellian eedf for many discharge condi-tions. Godyak and Piejak 1 measured non-Maxwellian eedf in atomic number 18 discharges using a Langmuir probe, and noted that the non-Maxwellian eedf could be considered as a summation of Maxwellian distributions of both groups of electrons. In opposite words, they considered the eedf as consisting of withdraw low temperature and richly temperature components. The senior high temperature component of the eedf was attributed to stochas-tic electron high temperature in the rf sheaths of the plasma enhanced by the Ramsauer effect. The coming into court of bi-Maxwellian distributions was attributed to insufficient energy transposition of the high and the low temperature components. corresponding results and conclusions carry been obtained by another(prenominal) groups.4?8 The bi-Maxwellian eedf alike has been obtained during estimator simulation and modeling studies of capaci-tively coupled rf discharges in argon and other gases.9?12 Godyak and co-workers pretend stated that the limitations of the energy issue and range of Langmuir probes puzzle role of low-energy electrons and detection of rela-tively high-energy electron tails unwieldy for some discharge conditions. The consistency of probe results obtained by many groups, along with simulation and modeling studies, check led to a get of widely accepted conclusions near the electron heating mechanisms in capacitively coupled rf plasmas. However, because of the capability problems of probe meth- ods, it is consequential that experimental results be confirmed by an independent technique. It is also important that the tem-perature and density of the low-temperature component of bi-Maxwellian eedf be determined truely. In this garner, we declare the results of electron property measurements of capacitively coupled rf plasmas make using the manner of laser Thomson scattering. optical maser Thomson scattering is a relatively complicated method experimentally, but has the significant advantages including a method that is non-perturbing and that experimental results can be inter-preted straightforwardly.

Previous studies have present the usefulness of this technique for perusal electron behav-ior in relatively high density plasmas,13?16 while we latterly pull the development of an experimental scheme capable of reservation accurate measurements in very low electron den-sity conditions, found in low pressure capacitively coupled rf plasmas.17 The gravel of this letter is to show the measured eedf in these plasmas and to compare the results with those obtained by other groups. Details of the experimental strategy were shown elsewhere 17 and we describe its most salient features here. The discharge sleeping accommodation was a cylindrically shaped stainless-steel vacuum chamber with a diam of three 100 mm. Argon plasmas were sustained between two parallel plate-electrodes make of stainless steel. The electrodes had a diam of 100 mm and were unlogical by 20 mm. The pep pill electrode was connected to a 13.56 megacycle power supply by dint of matching network, while the degrade electrode was connected to the chamber jetty and to the ground. The laser source was a Nd:YAG laser operated at the second harmonic wave continuance of 532 nm. It had a pulse en-ergy of 400 mJ, a pulse width of 7 ns, a propagate division of 0.5 mrad, and was operated at a bear rate of 10 Hz. The laser beam was injected in a even parallel to the electrode find and passed through the central skitter of the plasma. It was focused to the center of the chamber by a electron crystalline lens system with a central length of 670 mm. A beam dump, a viewing dump, baffles, and Brewster windows were used to minimize the stray accrue level. The staccato light was sedate by a lens with diameter of 130 mm and a focal length of 200 mm, at a! Electronic mail: mansour@asem.kyushu-u.ac.jp utilize physical science garner VOLUME 78, NUMBER 21 21 whitethorn 2001 3187 0003-6951/2001/78(21)/3187/3/$18.00 © 2001 American Institute of Physics Downloaded 18 may 2001 to 129.25.14.96. Redistribution adequate to(p) to AIP license or copyright, hold in http://ojps.aip.org/aplo/aplcr.jsp If you wish to get a full essay, order it on our website: Orderessay

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