摘要:

Radiofrequency discharges in low pressure fluorocarbon gases are used for anisotropic and selective etching of dielectric materials (SiO2and derivatives), a key step in the manufacture of integrated circuits. Plasmas in these gases are capable not only of etching, but also of depositing fluorocarbon films, depending on a number of factors including the ion bombardment energy, the gas composition and the surface temperature: this behavior is indeed responsible for etch selectivity between materials and plays a role in achieving the desired etched feature profiles. Free radical species, such as CFxand fluorine atoms, play important but complex roles in these processes. We have used laser‐induced fluorescence (LIF), with time and space resolution in pulsed plasmas, to elucidate the kinetics of CF and CF2radicals, elucidating their creation, destruction and transport mechanisms within the reactor. Whereas more complex gas mixtures are used in industrial processes, study of the relatively simple system of a pure CF4plasma is more appropriate for the study of mechanisms. Previously the technique was applied to the study of single‐frequency capacitively‐coupled “reactive ion etching” reactors, where the substrate (placed on the powered electrode) is always bombarded with high‐energyCFx+ions. In this case it was found that the major source of CFxfree radicals was neutralization, dissociation and backscattering of these incident ions, rather than direct dissociation of the feedstock gas. Subsequently, an inductively‐coupled plasma (ICP) in pure CF4was studied. This system has a higher plasma density, leading to higher gas dissociation, whereas the energy of ions striking the reactor surfaces is much lower (in the absence of additional RF biasing). The LIF technique also allows the gas temperature to be measured with good spatial and temporal resolution. This showed large gas temperature gradients within the ICP reactor, which must be taken into account in reactive species transport. In the ICP reactor we saw significant production of CF and CF2radicals at the reactor top and bottom surfaces, at rates that cannot be explained by the neutralization of incidentCFx+ions. These two species are also lost at very high rates in the gas phase. We postulate that these two phenomena are caused by electron‐impact excitation of these radicals into low‐lying metastable levels. The metastable molecules produced (that are invisible to LIF) diffuse to the reactor walls where they are quenched back to their ground state. In the afterglow the gas cools rapidly and contracts, causing gas convection. Whereas the density of the more reactive species decays monotonically in the afterglow, the density of CF2initially increases. This is partly due to the gas contraction, bringing back CF2(which is a relatively stable species) from the outer regions of the reactor, and partly due to chemical reactions producing CF2, as it is more thermodynamically stable than the other radical species such as CF and CF3. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843511

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

A short review of experiments dealing with excessive Doppler broadening of hydrogen and deuterium Balmer lines in various gas discharges is presented. Both old and new experimental data of excessive line broadening are discussed from the point of view of the collision model and the resonance transfer model. The results of several new experiments reported here, like the earlier ones, clearly support the collision model of excessive broadening. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843512

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Electrodeless discharge microwave powered ultraviolet limps are a special class of high power incoherent UV sources, conceptualized forty years ago for industrial processing applications. Because of the nonimaging character of the applications, the need for measuring averaged properties of the lamps’ exceeds the motivation to obtain detailed space‐resolved discharge parameters. This writing discusses measurements of the average plasma temperature of a 5.8kW high pressure mercury bulb and a XeCl* excimer bulb driven by the microwaves of the same power. First method is based on the black body radiance fit to the self‐absorbed 185nm and 254nm mercury lines. The second method is essentially Boltzmann plot method applied to the roto‐vibrational levels of B1/2 – X1/2 XeCl* molecular transition with a maximum at 308nm. We also present a procedure for evaluation of effectiveness of different bulb spectra to the given UV curing chemistry system independent from the Beer‐Lambert law. Conversely, the procedure can be used for the optimization of the chemistry to the chosen UV lamp radiance spectrum. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843513

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The up to date various aspects of plasma microfield notion development is outlined. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843514

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The physical, biological and technical background for high‐precision plasma surgery is prepared in a multi‐disciplinary team. The aim of the research is to achieve controlled removal of diseased cells and bacteria without harming the healthy rest of the tissue. For this purpose, a small, cold, flexible and non‐toxic plasma is developed (the plasma needle) and tested on cultured cells and bacterial samples. The needle is an atmospheric discharge induced by a radio‐frequency voltage applied to a metal pin. This plasma operates at room temperature, in the milliwatt power regime; it poses no risk of thermal or electrical damage to living tissues. Several beneficial responses of living cells to plasma treatment have been already identified. Plasma does not cause accidental cell death (necrosis), which leads to inflammation and tissue damage. Instead, it allows to detach cells from each other and from the scaffold, and thus to remove them in a non‐destructive way. Moreover, plasma is capable of bacterial inactivation. I parallel, we have determined the electrical and optical properties of the plasma and found a method of precise positioning of the plasma needle with respect to the treated tissue. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843515

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The results of the spatial distribution studies of electron densities, excitation and rotational temperatures and atomic line intensities of various elements in an atmospheric pressure mini‐MIP torch with tangential argon flow. The electron number density,ne, is determined from the width of the hydrogen H&bgr;486.13 nm line while excitation temperature,Texc, is evaluated from the Boltzmann plot of relative line intensities either of carrier gas‐argon or neutral iron that is introduced in the form of aerosols in MIP, The rotational temperatures,Trot, are determined from the relative intensities of OH (R2and Q1branch) electronic band A2&Sgr; − X2&Pgr; (0,0) and toN2+first negative systemB2 &Sgr;u+ − X2 &Sgr;g+(P branch). For the selected input power of 100 W, the influence of hydrogen in the wet and desolvated aerosols and support gas and the corresponding changes of the electron density, excitation and rotational temperature distributions are studied. The influence of potassium, low ionization potential element, to the spatial distribution ofne,TexcandTrotis studied also. Spatial intensity distributions and maximum intensities for investigate atomic line are determinate for the same conditions. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843516

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Results on studies of molecular spectra emitted in the initial stages of fullerene formation during the processing of graphite powder in induction RF reactor and evaporation of graphite electrodes in arc reactor are presented in this paper. It was found that C2radicals were dominant molecular species in both plasmas. C2radicals have an important role in the process of fullerene synthesis. The rotational‐vibrational temperatures of C2and CN species were calculated by fitting the experimental spectra to the simulated ones. The results of optical emission study of C2radicals generated in carbon arc plasma have shown that rotational temperature of C2species depends on carbon concentration and current intensity significantly. The optical emission study of induction RF plasma and SEM analysis of graphite powder before and after plasma treatment have shown that evaporation of the processed graphite powder depends on feed rate and composition of gas phase significantly. Based on the obtained results, it was concluded that in the plasma region CN radicals could be formed by the reaction of C2species with atomic nitrogen at smaller loads. At larger feed rate of graphite powder, CN species were produced by surface reaction of the hot carbon particles with nitrogen atoms. The presence of nitrogen in induction RF plasma reduces the fullerene yield significantly. The fullerene yield obtained in two different reactors was: 13&percent; in arc reactor and 4.1&percent; in induction RF reactor. However, the fullerene production rate was higher in induction RF reactor‐6.4 g/h versus 1.7 g/h in arc reactor. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843517

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

On the basis of the experimentally determined 26 prominent neutral neon (Ne I) line shapes (in the 3s‐3p, 3s‐3p′, 3s′‐3p′, 3s′‐3p and 3p‐3d transitions) the basic plasma parameters i.e. electron temperature (T) and electron density (N) have been obtained using the line deconvolution procedure, in a plasma created in a linear, low‐pressure, pulsed arc operated in pure neon. The mentioned plasma parameters have also been measured using independent experimental diagnostics techniques. Agreement has been found among the two sets of the obtained parameters. This recommends the deconvolution procedure for plasma diagnostical purposes. Self‐confidence of the method has checked using Ne I spectral lines which originate from different energy levels. The advance used of the method has been done in the way to find energy level from which it does not existing any more assumption of LTE.This method may be of interest also in astrophysics where direct measurements of the main plasma parameters (TandN) are not possible. With the development of space born spectroscopy the good quality spectra will be enabling to use this method. The separate electron (We) and ion (Wi) contributions to the total Stark width (Wt), which have not been measured so far, have also been obtained for neon spectral lines. The measured and calculatedWedata are compared to available theoreticalWevalues. It has found stronger influence of the ion contribution to the Ne I lines shape than the predicted ones calculated by the current theory. It has also tested the ion contribution to the Ne II lines shape. Small influence of the ion contribution to the some Ne II line shape has evidenced. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843518

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Simulation studies on argon glow discharges established between flat disc electrodes, at pressure × electrode separation (pd) of 45 Pa cm are reported, with special attention to heavy‐particle processes including excitation‐induced light emission. The discharges are investigated through self‐consistent hybrid modelling, consisting of a fluid description for components near local hydrodynamic equilibrium (slow electrons and ions), and Monte Carlo treatment of energetic electrons and heavy particles (ions and neutral atoms). The light emission profiles are analyzed for a wide range of operating conditions. The numerical results for the relative intensities and the shapes of the negative glow (created by electron impact excitation) and the cathode glow (created by heavy particle impact excitation) are in good agreement with experimental data obtained by Maric´ et al. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843519

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The results of experimental study of magnetic dipole (M1) transitions in highly charged ions of argon (Ar9+, Ar10+, Ar13+and Ar14+) and krypton (Kr18+and Kr22+) are presented. The forbidden transitions of the highly charged ions in the visible and near UV range of the photon emission spectra have been measured with accuracy better than 1 ppm. Our measurements for the “coronal lines” are the most accurate yet reported using an EBIT as a spectroscopic source of highly charged ions. These precise wavelength determinations provide a useful test and challenge for atomic structure calculations of many‐electron systems. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843520

出版商:AIP    

年代:1904

数据来源: AIP