Bulletin of the American Physical Society
60th Gaseous Electronics Conference
Volume 52, Number 9
Tuesday–Friday, October 2–5, 2007; Arlington, Virginia
Session SRP1: Poster Session III |
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Room: Doubletree Crystal City Crystal Ballroom C, 4:00pm - 6:00pm |
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SRP1.00001: MATERIALS PROCESSING IN LOW PRESSURE PLASMAS: ETCHING, DEPOSITION, NEW MATERIALS |
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SRP1.00002: Plasma Etching of Extremely High Aspect Ratio Features: Twisting Effects Mingmei Wang, Ankur Agarwal, Yang Yang, Mark J. Kushner Plasma etching of small features having very large aspect ratios allows only a marginal CD variation. Etching extremely high aspect ratios ($\sim $100) necessitates obtaining a uniform plasma density with high energy ions to mitigate the effect of energy losses due to sidewall impacts. Undesirable behavior such as tapering and twisting has been observed in etching of such features. Twisting is the sometimes sudden turning of a via or trench from the vertical to a side angle which occurs nearly randomly. For example, of three adjacent features, only one may display the behavior. One theory on the source of twisting is charging within and adjacent to the feature. In this talk, results from a computational investigation of plasma etching of extremely high aspect ratio features will be discussed. The 2-d Hybrid Plasma Equipment Model was linked with the Monte Carlo Feature Profile Model (MCFPM) to assess the effect of charging on the etching of high aspect ratio features. The MCFPM was modified to include the effects of charging by electrons and ions, including solution of Poisson's equation and conduction current through solid materials. Results will be discussed for an electron cyclotron resonance plasma reactor etching of SiO$_{2}$ in fluorocarbon plasmas. [Preview Abstract] |
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SRP1.00003: Potential fluctuation induced by discrete particle effect in a nano-scale trench Taesang Lee, Seongsik Kim, Choongseock Chang A simplified two-dimensional Monte Carlo simulation is performed to investigate the electric field fluctuations caused by strong Coulomb interactions between discrete particles in nanometer scale trenches. It is found that the discrete particle effect should be an important part of the nano-scale trench physics, raising the ion orbit scatterings in the trench, enhancing the ion deposition on the side walls, and dispersing the material contact energy of the incidence ions. [Preview Abstract] |
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SRP1.00004: Sheath control with plasma wall bias for the collimated ion beam generation Seunghoon Park, TaeSang Lee, Hoyul Baek, Choong-Seock Chang It is important to find collimated ion beam condition for neutral beam generation. Ion beam quality is dependent of acceleration grid hole geometry and plasma properties. We focus on dependence on plasma properties such as sheath dynamics. In order to form sheath in high density plasma, ICP like heating is modeled and 2D particle in cell (PIC) simulation is performed. It is confirmed that the sheath is deformed by plasma density and Sheath is able to be controlled by plasma wall bias. [Preview Abstract] |
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SRP1.00005: Low-Temperature, Remote Plasma Oxidation of SiC for MOS Device Applications. J.M. Williamson, B.A. Tolson, S.F. Adams, J.D. Scofield Silicon carbide is considered a promising semiconductor material for high-frequency, high-power, and high-temperature devices because of its large band gap, high thermal conductivity, high breakdown strength and large saturated electron drift velocity. The performance of SiC metal oxide semiconductor (MOS) devices is limited by the defect density of the semiconductor/oxide interface. High-temperature thermal oxidation leaves carbon impurities at the SiC/SiO$_{2}$ interface resulting in high defect state densities with concomitant lower channel conductivity and decreased device efficiency. To circumvent the high sample temperatures used in thermal oxidation, plasma assisted oxidation of SiC wafers was investigated using O$_{2}$/Ar gas mixtures in a remote microwave plasma reactor. Results will be presented for the electrical and material properties of oxide layers as a function of gas mixture, surface temperature, and substrate bias. These results will be correlated with plasma properties determined by in-situ optical diagnostics. [Preview Abstract] |
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SRP1.00006: Modification of Biased Bulk Nb Surface with Ar/Cl$_{2}$ Microwave Discharge Plasma J. Upadhyay, M. Raskovic, S. Popovic, L. Vuskovic Microwave glow discharge in Ar/Cl$_{2}$ mixture was used for plasma treatment of bulk niobium surface. The samples were connected to a negative d.c. and radio-frequency bias. This treatment consisted of simultaneous sputtering, favored by sheath formation, and etching, favored by the presence of reactive chlorine atoms. Both of these processes enable the removal of impurities and increase smoothness of the Nb surface [1]. The rate of surface removal was correlated with the concentration of Cl radicals (Cl, Cl$^{+ }$, Cl$^{-})$ in the discharge and the temperature of sample. To determine these parameters we developed a set of techniques for a comprehensive plasma characterization. Optical and electrical methods were used to determine plasma parameters. Plasma emission actinometry was used to estimate the absolute densities of Cl, Cl+ and Cl$_{2}$ under the discharge conditions optimal for the surface treatment. [1] M. Raskovic, et al., Nuclear Instruments and Methods in Physics Research A 569 663--670 (2006). [Preview Abstract] |
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SRP1.00007: Titanium Nitride Coatings Prepared by Reactive Sputtering on Steel Saoula Nadia, Henda Karim, Kesri Rafika Titanium nitride is used as coating on cutting tools because of their excellent mechanical properties such as high hardness and high wear resistance. Its chemical inertness gives rise to its application as corrosion protective coating. It's an excellent barrier material with good electrical conductivity in various metallization structures of advanced microelectronic devices. Finally, the golden glance of TiN established its use as decorative coating in the fashion jewellery and in architecture. The deposition process studied, in this work, use RF sputtering of a pure titanium target in a reactive nitrogen/ argon gas mixture, at various conditions. The substrates are steel. The main variables investigated are the composition of the Ar/N$_{2}$ gas mixture, the total pressure, the deposition time and the discharge power. The aim of this work is to evaluate the performances of a local-made RF plasma reactor. The attention was given to the study of the structure, the composition of titanium nitride deposits, which have a considerable influence on their hardness. The deposited coatings were characterized by X-ray diffraction, energy dispersive spectroscopy (EDS) and micro-indentation. [Preview Abstract] |
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SRP1.00008: Direct liquid droplet injection for PECVD D. Ogawa, M. Goeckner, A. Sra, R. Timmons, L. Overzet Plasma enhanced chemical vapor deposition (PECVD) is a versatile technique for depositing thin films. For common PECVD, vapor phase precursors have been required. This limitation has led to several methods for allowing the use of low-vapor pressure precursors; for example, entrainment of the precursor vapor in a heated gas flow using bubblers or vaporization sources is common. We are using a new approach, mixing the low vapor pressure precursor into a high vapor pressure solvent and directly injecting the mixture into the low pressure plasma environment as micro-droplets using an automotive fuel injector. We have gone as far as to inject nanoparticles of iron into the plasma by suspending them in hexane (or ethanol). In fact, we believe that metals, dielectrics, superconductors, aromatics, proteins, viruses, etc. could all potentially be injected into low pressure plasma environments using this simple and effective technique. Control over the liquid injection is possible using either the differential pressure across the fuel injector or the time the injector is open. The resulting films formed by the plasma decomposition of the high vapor pressure fluid contain the nanoparticles suspended in the film matrix. We will show that the deposited film depends on the pressure, injection rate and plasma conditions. [Preview Abstract] |
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SRP1.00009: Modeling the direct injection of liquid droplets into low-pressure environments and plasmas I. Saraf, M. Goeckner, L. Overzet A model for the evaporation of micron-sized liquid droplets injected into low pressures and plasmas is being developed. This model differs from higher pressure models in that it assumes the mean free path is greater than the droplet diameter and therefore allows one to assume that the transport is non-diffusive. The model accounts for both particle and heat flux into and out of the droplet (by collisions with gas molecules, evaporation and the return of molecules {\{}freeze-on{\}}). With the addition of plasma, several other terms are added (ion bombardment, recombination etc.). The model runs in Matlab and indicates that the time required for the droplet to fully evaporate is a function of the background pressure, initial (wall) temperature, the number of droplets inserted simultaneously and initial size. A typical evaporation time for a 50 micron diameter droplet is 7 seconds for hexane and up to 25 seconds for ethanol without plasma. Upon insertion into the low pressure environment, the temperature of the droplet decreases quickly as the first few microns evaporate. The temperature falls to a minimum value, generally below the freezing point where the heat flow balances. This sets the evaporation rate and explains why the evaporation time decreases with increasing the pressure, the number of droplets and the initial droplet temperature. Supported in part by SPRING/AFOSR Grant FA9550-05-1-0393. [Preview Abstract] |
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SRP1.00010: PLASMA DIAGNOSTICS: OPTICAL, ELECTRICAL, OTHER |
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SRP1.00011: Ion Energy Measurements in Continuous Electron Beam-Generated Plasmas Scott Walton, Evgeniya Lock, Richard Fernsler The US Naval Research Laboratory has developed a plasma processing system that relies on a magnetically collimated, sheet of multi-kilovolt electrons to ionize the background gas and produce a planar plasma. High-energy electron beams are efficient at producing high-density plasmas (ne $>$ 1010 cm$^{-3}$) with low electron temperatures (Te $<$ 1.0 eV) over the volume of the beam, resulting in large fluxes of low-energy ions ($<$ 5 eV) at surfaces located adjacent to the electron beam. In this work we present plasma diagnostic results using a recently developed, continuous electron beam source. In this work, an energy-resolving mass spectrometer is used to determine the ion energies and fluxes at electrodes located adjacent to the electron beam. These measurements are made as a function electron beam intensity and energy, and electrode bias in argon, nitrogen, and their mixtures at various total pressures. We employ both DC and RF biasing schemes in an effort to provide well-controlled incident ion energies for applications requiring both low and high ion energies. The results of this work are related to bulk plasma properties determined using Langmuir probe diagnostics (See paper by E.H. Lock et al. at this conference). [Preview Abstract] |
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SRP1.00012: XUV Spectroscopic Diagnostics for Microplasma Research Dan Stutman, Michael Finkenthal Microplasmas are high density, dc or pulsed discharges produced in cavities having 10-100 $\mu $m typical size. Although spectroscopy is the best tool for their characterization, important plasma parameters such as electron density, temperature, energetic electron fraction and impurity content are difficult to measure using visible light emission. Since the bulk microplasma emission is expected to be in the XUV ($\approx $ 100-1500 {\AA}), we study the possibility of adapting XUV diagnostics developed for magnetically confined plasmas, for use in microplasma research. For instance, a tool that could enable, with appropriate modeling, the characterization of the EEDF in dc microplasmas would be a transmission grating XUV `radiometer' that measures the spectral distribution of the emitted power. Also a device based on `multi-energy' filtered photodiodes, similar to that we developed for fast temperature diagnostic in tokamaks, could be used for EEDF characterization in pulsed microplasmas. In addition, the proposed diagnostics will enable new research directions, such as the study of turbulent fluctuations. To benchmark the XUV emission models for microplasma application, we propose to use a scaled-up macroscopic hollow cathode discharge, in which conventional diagnostics can be used for reference measurements of the bulk density, temperature and non-thermal component. [Preview Abstract] |
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SRP1.00013: Electrical diagnostic of a magnetized RF discharge in CH$_{4}$ created by a multihole cathode used for a-C:H deposition films. Djerourou Samira, Ourchabane Mohemed, Henda Karim The present work is carried out in the context of the electrical study of a reactor used for a-C:H deposition. We have studied the influence of the operation system parameters (incident power, pressure and magnetic field) on the self- bias voltage and on the saturation ion current density. These measurements have been made over a wide range of incident power inputs of 50-300 W and pressures of 20-100 mTorr. For electrical diagnostic, the results obtained showed that the energy and ion flow bombarding the substrate presented a maximum values at high incident power and decreased with pressure. A comparative study between confined and unconfined discharges showed that the magnetic field had a significant influence on the electric parameters of the discharge. The first correlation between electrical parameters and a-C:H deposition was found, polymer-like thin films with high deposition rates can be obtained at low pressure and with grounded substrate holder. [Preview Abstract] |
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SRP1.00014: Density and lifetime evaluation of weakly ionized plasma for laser-triggered lightning by means of laser absorption Michiteru Yamaura The potential ability of lasers to control lightning can be improved by using a train of pulses with sub-millisecond separations [1-2]. Laser-triggered experiments in a small-scale (10 mm gap) atmospheric discharge facility show that the triggering is dramatically enhanced when a five-pulse train of sub-Joule energy is used instead of a single pulse. This effect increases rapidly as the pulse interval is reduced. It appears that at a sub-millisecond pulse interval, sufficient positive and negative ions survive in subsequent pulses, thus enabling easy deionization. Hence, significant plasma build-up occurs from one pulse to the next. However, this persistence of ions would appear to imply that the rate of recombination (effectively a charge transfer between ions) is considerably lower than previously believed. \newline \newline [1] M. Yamaura: Appl. Phys Lett. \textbf{88} 251501 (2006). \newline [2] M. Yamaura: J. Appl. Phys. \textbf{98} 043101 (2005). [Preview Abstract] |
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SRP1.00015: Measuring the Ion Flux to Deposition Substrate in Hollow Cathode Plasma Jet Petr Virostko, Zdenek Hubicka, Petr Jelinek, Martin Cada, Petr Adamek, Milan Tichy Different electrical methods of obtaining negative bias of deposition substrate and measuring the resulting positive ion flux in DC and DC pulsed hollow cathode plasma jet deposition system are compared. Ion fluxes are determined for pulse-modulated and continuous RF (13.56 MHz), and for pulsed DC bias of the substrate for different bias and discharge conditions. An electrical model of the feed line to the substrate is proposed to determine RF current and voltage waveforms on the RF biased substrate from the waveforms measured outside of the reactor chamber. The resulting RF current waveforms are compared to a fluid numerical model of an RF biased electrode. The ion fluxes determined from the discharging of capacitor in series with the substrate in pulse-modulated RF bias are comparable with those measured for pulsed DC bias, while ion fluxes determined for continuous RF bias differ significantly. Possible explanations of this discrepancy are discussed. [Preview Abstract] |
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SRP1.00016: Electron-Beam Generated Air Plasma: Electrical and Optical Diagnostic Details Robert Vidmar, Kenneth Stalder Diagnostics associated with a pulsed 1-ms 100-keV 20-mA electron beam that generates air plasma are discussed. A mesh sensor measures the beam current up-stream to an electron-beam transmission window. The transmission window separates the electron source from a 400-liter test cell, operated from 1 mTorr to 635 Torr using laboratory air. 10-GHz RF amplitude and phase measurements quantify electron density. A diode array spectrometer is used to measure optical emissions from the plasma typically dominated by neutral and ionic nitrogen emissions. UV absorption at 254 nm is used to detect ozone. Concentrations of other species such as H$_{2}$O, CO$_{2}$, CO, NO, and N$_{2}$O are monitored by tunable diode laser absorption spectroscopy. Data from these diagnostic systems, obtained during a single shot, will be discussed and compared. This work is supported by the Air Force Research Laboratory under grant numbers FA9550-04-1-0015 and FA9550-04-1-0444; and State of Nevada matching funds. [Preview Abstract] |
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SRP1.00017: The role of Oxygen triplets in plasma diagnostic Vladimir Milosavljevic, Albert Ellingboe, Stephen Daniels The oxygen 777nm triplet is very important for the measurement of atomic oxygen in low pressure plasmas, since the 777.42nm spectral line is frequently used for actinometry. Cascade processes from the 6s and 5s energy states to the upper level of the 777nm triplet correlate with errors in the measurement of atomic densities. In this paper we present the intensity dependence of the oxygen 777 (777.19nm, 777.42nm, 777.54nm), 543 (543.69nm, 543.58nm, 543.52nm) and 645 (645.60nm, 645.44nm, 645.36nm) triplets on plasma chemistry. The spectral lines from the 777 triplet belong to the transition 3s--3p and multiplet $^5$S$^0$-$^5$P. They have same lower energy (E$_f$) level of 9.15eV, with upper energy (E$_i$) levels of about 10.74eV. The lines from the 543 and 645 triplets have different E$_i$ levels; for the 543 triplet all spectral lines have E$_i$=13.02eV, while for the spectral lines from the 645 triplet E$_i$ are 12.66eV. The E$_f$ level for spectral lines from the 645 and 543 triplets are E$_i$ level for spectral lines from the 777 triplet. The experiment are performed in a Inductive plasma source operated at 13.56MHz, with 4MHz substrate bias. Working gases are Ar-O$_2$-C$_4$F$_8$ mixtures, with the addition of helium at the back side of a Oxide coated wafer. Gas pressure is varied from 2 to 6 Pa; flows of 300sccm of Ar and O$_2$ and C$_4$F$_8$ are both varied from 0 to 20 sccm. Source power is varied from 0 to 600 W, and bias power from 0 to 1200 W. [Preview Abstract] |
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SRP1.00018: Comparison of helium two-step plasma emission with that predicted from measured cross sections C.A. DeJoseph, Jr., V.I. Demidov, J.C. Blessington Plasma emission from the afterglow of a low pressure, 100{\%} modulated, rf discharge, can originate from collisions between metastable atoms and fast electrons. The fast electrons are generated by collisions between pairs of metastables (Penning ionization of one metastable by another) and collisions of metastables with slower electrons (collisions of the second kind). Using time-resolved Langmuir probe data, we have measured the electron energy distribution function (EEDF) containing these fast electrons in a helium afterglow. The EEDF data were used, along with measured excitation cross sections out of the 2s$^{3}$S metastable level [1], to predict relative intensities of various He emission lines seen in the afterglow. A comparison between the measured and predicted emission will be presented. \newline [1] Boffard, J. B., Lagus, M. E., Anderson, L. W., and Lin, C. C., Phys Rev. \textbf{A 59} (1999) 4079. [Preview Abstract] |
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SRP1.00019: Probe measurements in electronegative plasmas: modeling the perturbative effects of the probe E.A. Bogdanov, A.A. Kudryavtsev, K. Yu. Serditov, C.A. DeJoseph, Jr., V.I. Demidov A basic property of an electronegative plasma is its separation into two distinct regions: an ion-ion region far from boundaries and a near-boundary electron-ion region, where negative ions have practically negligible density. This is due to the influence of the ambipolar electric field, which depends on electron (not negative ion) plasma parameters. This electric field ``holds off'' negative ions from the boundary, as the ions have lower mobility and temperature compared to the electrons. Therefore, negative ions will be repelled by any object inserted into the plasma. This can lead to errors in measurements of negative ion parameters by any invasive method. Numerical modeling of electric probes in an argon-oxygen plasma clearly demonstrates possible errors of direct measurements of negative ion current. This can also affect results from the photo-detachment method and direct measurements of negative ion energy distribution. [Preview Abstract] |
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SRP1.00020: Electrostatic probe measurement and estimation of the electronegativity for low-pressure inductively coupled SF$_{6}$ and O$_{2}$ plasmas Tae Hun Chung, Sun Young Kang, Eun Young Kim Electrostatic probe measurements for low-pressure inductively coupled SF$_{6}$ and O$_{2}$ plasmas are performed. From the probe I-V curves, we measure the electron saturation current, the positive ion saturation current, and the electron temperature. By using the ratios of these parameters at three adjacent pressure points, we calculate the electronegativity of the discharges at those pressures. By using the electronegativity and the electron density measured from probe I-V curve, we estimate the negative ion density. The positive ion density is calculated either by the Laframboise OML theory or by the sum of the electron density and the negative ion density. The validity of this approach is discussed and compared to other methods in estimating the negative ion density. The variations of the charged species density with pressure and power are investigated. In addition, mass spectra of SF$_{6}$ and O$_{2}$ plasmas are obtained to determine the various species in the discharge and the effective mass of the positive ions. [Preview Abstract] |
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SRP1.00021: Behavior of Excited Oxygen Atoms in Rare gas mixture O$_{2}$ Surface Wave Excited Plasma Keigo Takeda, Seigo Takashima, Masaru Hori Excited oxygen atom (O($^{1}$D$_{2}))$ has attracted very much on the oxygen-based plasma processes, such as plasma oxidation, surface cleaning, resist ashing, etc. Since it is supposed that the O($^{1}$D$_{2})$ atom is the most reactive species in all species in the oxygen-based plasma. Therefore, it is strongly required to investigate the behaviors of O($^{1}$D$_{2})$ atom in the oxygen-based plasmas, the quantitative information of O($^{1}$D$_{2})$ atom have never been clear, because the convenient light sources for absorption spectroscopic techniques of O($^{1}$D$_{2})$ atoms have not developed. The vacuum ultraviolet laser absorption spectroscopy (VUVLAS) has a great potential to measure the atomic radicals in the process plasmas. Therefore, in this study, we have measured the absolute density of O($^{1}$D$_{2})$ atom in the rare gas mixture O$_{2}$ surface wave excited oxygen plasma (SWP) by using VUVLAS with tunable VUV laser. The absolute densities of O($^{1}$D$_{2})$ atom in the O$_{2}$/Ar and O$_{2}$/Kr SWPs were evaluated as a function of various plasma conditions. From these results, the O$_{2}$/Ar SWP has a potential to realize the high O($^{1}$D$_{2})$ atom density compared with the O$_{2}$/Kr SWP and the density in the O$_{2}$/Ar SWP was the maximum around 2$\times $10$^{12}$ cm$^{-3}$ at the high Ar flow rate ratio and low pressure. [Preview Abstract] |
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SRP1.00022: Radical density measurement in VHF C$_{2}$F$_{6}$/H$_{2}$ plasma used for carbon nanowall growth Mineo Hiramatsu, Satoru Kato, Hajime Sasaki, Wakana Takeuchi, Shingo Kondo, Koji Yamakawa, Masaru Hori Carbon nanowalls (CNWs), two-dimensional carbon nanostructures consisting of plane graphene layers standing on the substrate, have been grown recently. The large surface area and thin edges of CNWs would provide potential applications in energy storage, as electrodes for fuel cells and field emission display. The morphologies and growth rate of CNWs depend on the types of carbon source gases and the amount of H atoms injected. In this work, CNWs were fabricated using VHF C$_{2}$F$_{6}$ PECVD with H radical injection, which was developed for the large-area growth of CNWs with reasonable growth rate. This system consists of a parallel-plate VHF (100 MHz) capacitively coupled plasma (CCP) region and a surface wave microwave (2.45 GHz) excited H$_{2}$ plasma as a radical source. A carbon source gas (C$_{2}$F$_{6})$ was introduced into the VHF CCP region. By using this system, the heated substrate was showered with fluorocarbon radicals as well as plenty of H atoms in a controlled manner. Absolute H and C atom densities in the plasma were measured by vacuum ultraviolet absorption spectroscopy as functions of input power and pressure in order to investigate the growth mechanism of CNWs. The correlation between CNW growth and radical densities was discussed. [Preview Abstract] |
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SRP1.00023: Measurements of electron temperature and argon metastable density by measuring optical emission in inductively coupled plasma. Young-Kwang Lee, Kwang-Tae Hwang, Min-Hyong Lee, Chin-Wook Chung To obtain electron temperatures and argon metastable number densities at various powers (100 W to 1 kW) and pressures (2 mTorr to 20 mTorr), a spectroscopic method [1] is used. The method is based on the availability of experimental relative emission intensities of only four argon lines that originate from 4p argon levels. Electron temperatures measured by the optical emission lines are compared with those by a Langmuir probe. They were in close agreement. Furthermore, the metastable densities from the model were estimated and presented. \newline \newline [1] D. Mariotti, Y Shimizu, T. Sasaki, N. Koshizaki, Appl. Phys. Lett. 89, 201502 (2006) [Preview Abstract] |
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SRP1.00024: Langmuir probe perturbation in plasma distribution measurement in an inductively coupled plasma SungHo Jang, JinSung Kim, KyeongHyo Lee, ChinWook Chung A single Langmuir probe system [SLP2000$^{TM}$, Plasmart, INC] was used for the measurement of radial density. The probe was located at 4cm below a dielectric window and the measurement was carried at 25mTorr at various rf powers (13.56MHz). It was found that symmetric radial density distribution becomes asymmetric as rf power increases. To investigate the cause of this asymmetric density distribution, a wise probe$^{ TM }$(P{\&}A Solutions) that can measure plasma densities and the electron temperatures in real-time was installed on the chamber wall. At high rf powers, as the probe body goes in, the plasma density measured by the wise probe is decreased. This indicates that whole plasma density is affected by the probe intrusion. It appears that the Langmuir probe passes through the skin layer and the probe body impedes electron heating process in the skin layer. The probe measurement method to avoid this perturbation is presented. [Preview Abstract] |
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SRP1.00025: Effect of multiphoton ionization in laser Thomson scattering measurements A. Kono, K. Fukuyama, M. Aramaki In laser Thomson scattering measurements of electron density and temperature, one should be careful about production of electrons in the scattering volume via laser irradiation. It is generally assumed that Ar plasma is free from such laser perturbations. However, in our measurements for inductively coupled Ar plasma using a frequency-doubled YAG laser (532 nm), Thomson scattering spectra obtained from measurements with different laser energy densities at the focal point differ significantly, when the discharge power is low and hence the ratio of the metastable Ar atom density to the electron density is relatively large. This suggests that multiphoton ionization of metastable Ar atoms may affect the measurement significantly. To clarify the phenomenon, an experiment for determining the ionization yield at the laser focal point in the Ar gas containing a known concentration of metastable Ar atoms is being carried out. The laser beam is focused at the center of a small dc-biased parallel-plate probe and the laser-induced probe current is measured. Preliminary measurements indicate successful detection of the current due to multiphoton ionization of metastable Ar atoms, the efficiency of which is to be quantified. (Work supported by Grant-in-aid 18540491 from MEXT Japan.) [Preview Abstract] |
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SRP1.00026: Electrical characteristics and comparison of two configurations of plasma needle Gordana Malovic, Nevena Puac, Sasa Lazovic, Antonije Djordjevic, Zoran Petrovic Nonequilibrium plasmas is proved to be able to produce chemically reactive species at a low gas temperature while maintaining uniform reaction rates over relatively large areas. Plasma needle is one of the atmospheric pressure sources that can be used for treatment of living matter which is highly sensitive when it comes to low pressure or high temperatures (above 40\r{ }C). Before any application, it is necessary to examine the properties of such source as well as possible and define the optimum conditions for the specific treatment. For that purpose, it is particularly important to know electrical characteristics of the plasma needle, i.e., the power transmitted to the plasma. In order to achieve that, we have developed derivative probes previously used by Puac \textit{et al.}[1] for measuring transmitted power in low pressure CCP RF discharge. In this paper we will make a comparison between two configurations of plasma needle that we have used in treatment of biological samples. Difference between these two configurations lays in additional copper ring that we have placed around glass tube at the tip of the needle. [1] Puac \textit{et. al}, Plasma Processes and Polymers, Eds. R. d'Agostino, P. Favia, C. Oehr and M.R. Wertheimer, (Whiley: (2005) p~193-203 [Preview Abstract] |
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SRP1.00027: Measurement of the electron temperature on microwave surface wave plasmas powered by the radial-line slot antenna Minkyu Kim, Lee Chen A Langmuir probe measurement system was built to study the surface wave plasma produced by radial-line slot antenna (RLSA) [1]. The measurements were performed on the bulk plasma under wide ranges of pressure (50 -- 1000 mTorr) and power (1 -- 5 kW). General characteristics of surface wave plasma were shown in the measurements through the I-V curve analysis. The electron temperature is low, $\sim $ 1 eV, and the plasma densities is high, $\ge $ 10$^{11}$ cm$^{-3}$. Additional higher electron temperatures were shown in the I-V curves. This second electron temperature shown in the IV curves has different trend from the lower electron temperature. The second temperature is a function of pressure. When the pressure increases, the second electron temperature also increases. EEDF/EEPF analysis is also performed to study the trend of the second electron temperatures. \newline \newline [1] C. Tian, T. Nozawa, K. Ishibasi, H. Kameyama, and T. Morimoto, ``Characteristics of large-diameter plasma using a radial-line slot antenna,'' J. Vac. Sci. Tech. A24, Vol. 4, Jul. 2006. [Preview Abstract] |
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SRP1.00028: Langmuir probes in flowing plasmas Peter Sheerin, Miles M. Turner Electrostatic probes are a classic method for inferring plasma parameters in many circumstances. Such probes are not easy to interpret when the plasma is flowing with respect to the probe, because there is not a clear theory based on elementary assumptions. Mach probes are a commonly accepted method, but the theory of such probes is not clearly founded on first principles. This paper considers an alternative theory, which is firmly based on first principles. We discuss the basis of this approach, and we present self-consistent particle-in-cell simulations with two space-dimensions as a benchmark for the analytical theory. In particular, we discuss the validity of the theory in the limit of small Mach number, which is the critical case. [Preview Abstract] |
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SRP1.00029: Surface Analysis by Plasma Assisted Desorption Ionisation Mass Spectrometry (PADI-MS) Y.A. Gonzalvo, T.D. Whitmore, P.J. Hatton, M.E. Buckley, D. Seymour, C.L. Greenwood, J.A. Rees, L.V. Ratcliffe, D.A. Barrett, F.J.M. Rutten, M.R.S. McCoustra Plasma assisted desorption/ionisation mass spectrometry (PADI-MS) is a surface analysis technique that yields sample information under ambient conditions of pressure and humidity without any surface preparation. It is achieved by directing a non-thermal atmospheric plasma onto the surface of interest. Desorption occurs from the surface and the subsequent ionisation products are detected in real time by using an atmospheric sampling quadrupole mass spectrometer. We have demonstrated the detection of active ingredients in a range of pharmaceutical and other samples, demonstrating the potential of the technique for high throughput screening in a pharmaceutical or forensics environment. [Preview Abstract] |
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SRP1.00030: IONIZATION OF ATOMS AND MOLECULES |
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SRP1.00031: Comparison of Ion Chemistries in Octafluoro-2-butene ($2$-C$_{4}$F$_{8})$ and in Octfluorocyclobutane ($c$-C$_{4}$F$_{8})$ Charles Jiao, Charles DeJoseph, Alan Garscadden $2$-C$_{4}$F$_{8}$ is one of the promising candidates to replace $c$-C$_{4}$F$_{8}$ that has been widely used for dielectric etching but is not environmentally friendly. In this study we have investigated electron impact ionization and ion-molecule reactions of $2$-C$_{4}$F$_{8}$ using Fourier transform mass spectrometry (FTMS), and compared the results with those of $c$-C$_{4}$F$_{8}$ we have studied previously. Electron impact ionization of $2$-C$_{4}$F$_{8}$ produces 15 ionic species including C$_{4}$F$_{7,8}^{+}$, C$_{3}$F$_{3,5,6}^{+}$, C$_{2}$F$_{4}^{+}$ and CF$_{1-3}^{+}$ as the major ions. The total ionization cross section of $2$-C$_{4}$F$_{8}$ reaches a maximum of 1.8x10$^{-15}$ cm$^{2}$ at 90 eV. The ionization is dominated by the channel forming the parent ion C$_{4}$F$_{8}^{+}$ from 12 to 18 eV, and by the channel forming C$_{3}$F$_{5}^{+}$ from 18 to 70 eV. After 70 eV, CF$_{3}^{+}$ becomes the dominant product ion. Among the major ions generated from the electron impact ionization of $2$-C$_{4}$F$_{8}$, only CF$^{+}$, CF$_{2}^{+}$ and CF$_{3}^{+}$ are found to react with $2$-C$_{4}$F$_{8}$, via F$^{-}$ abstraction or charge transfer mechanism. The charge transfer reaction of Ar$^{+}+2$-C$_{4}$F$_{8}$ produces primarily C$_{4}$F$_{7}^{+}$. [Preview Abstract] |
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SRP1.00032: OTHER ATOMIC AND MOLECULAR COLLISION PHENOMENA |
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SRP1.00033: Plasma-Screening Effects on the Electron-Impact Ionization of Atoms / Molecules and Ions Embedded in Weak Plasma Bhushit Vaishnav, K.N. Joshipura, S. Gangopadhyay Plasma screening effects on electron induced atomic collision properties have attracted considerable research attention, because of applications in inertial confinement fusion and X-ray lasers etc. The theoretical interest is to examine the ionization of atomic/molecular targets by the impact of electrons in plasma. Basically the electron scattering problem is treated in a semi-empirical approach in the complex scattering potential ionization contribution (CSP-ic), to calculate \textit{total ionization cross section} as a dominant part of total inelastic cross sections. This approach has been successful for number of (free) atomic and molecular targets in [1]. This paper extends the method to the collision processes in plasma and the relative contribution of ionization has been identified. We consider He$^{+}$ ion embedded in weak plasma. The static potential of the e-He$^{+}$ system in plasma environment is derived by us. Results will be discussed in the Conference. \newline \textbf{References:} [1] K N Joshipura, Bhushit G Vaishnav and Sumona Gangopadhyay, Int. J. Mass. Spectrom. \textbf{261} (2007) 146. [Preview Abstract] |
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SRP1.00034: Surface catalytic contributions to molecule conversion in plasmas Richard Engeln, Rens Zijlmans, Onno Gabriel, G\"oksel Yagci, Daan Schram, Stefan Welzel, J\"urgen R\"opcke, Frank Hempel The contribution of surface-related processes to the formation of new types of molecules in a recombining plasma with a low electron temperature is investigated. The recombination of a highly dissociated mixture of nitrogen and oxygen is studied with a combination of tuneable diode laser absorption spectroscopy and mass spectrometry. A simulation in CHEMKIN, based on a simplified set of chemical reactions, has been developed to describe the system in detail and to determine the contributions of volume processes and surface-related processes. With a sticking coefficient of 0.1 for the radials for all studied conditions, a chance of unity for Eley-Rideal processes to be successful, a desorption energy of 0.7 eV for NO molecules and relatively low activation energies, around 0.5 eV, for the Langmuir-Hinshelwood processes gives a good agreement with the measurements. We show that NO$_{2}$ can only be formed at surfaces in our system, whereas NO and N$_{2}$O are at least for a significant fraction formed at the surfaces of the reactor. Especially at low pressure conditions and at low oxygen admixture, the role of the surfaces is pronounced. [Preview Abstract] |
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SRP1.00035: OTHER PLASMA TOPICS |
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SRP1.00036: Spectroscopic investigations into extraordinary phenomena in hydrogen plasmas with certain catalysts Sander Nijdam, Andreas van den Brink, Niels Driessen, Peter van Noorden, Ruud de Regt, Tim Righart, Gerrit Sitters, Eddie van Veldhuizen, Ruud Wijtvliet, Gerrit Kroesen In recent years hydrogen plasmas have been created that display extraordinary behavior, like breakdown at low electric fields, anomalous plasma afterglow, excessive hydrogen Balmer-$\alpha $ spectral line broadening and EUV and VUV emission. Experiments have been done on three types of hydrogen discharges in order to reproduce the extraordinary plasma behavior observed. We have investigated these hydrogen discharges with different spectroscopic measuring devices. We focused on broadening of the hydrogen Balmer-$\alpha $ line and the emission of EUV and VUV radiation. The measurements in the visible part of the spectrum have been performed using a B{\&}M{\-}100 type (1000 mm) Czerny-Turner monochromator attached to a CCD camera or a photomultiplier. For the VUV and EUV measurements we have used three different monochromators: a Jobin Yvon LHT 30 (320 mm, near grazing incidence), a Jobin Yvon HR 1500 (1500 mm, normal incidence) and a McPherson Model 234/302 vacuum monochromator (200 mm, normal incidence). In all cases a scintillator plate has been used to convert the diffracted UV radiation into visible light which was quantified by a CCD camera or a photomultiplier. [Preview Abstract] |
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SRP1.00037: Deterministic Plasma-aided Nanofabrication research within the International Plasma Nanoscience Network Igor Levchenko, Kostya (Ken) Ostrikov, Shuyan Xu Plasma Nanoscience is a subfield at the cross-roads of cutting-edge nanoscience, plasma and gas discharge physics, materials and surface science, engineering, astrophysics and bionanotechnology. Understanding how plasma-based nanoassembly works in natural environments and translating this knowledge to laboratory and industrial nanofabrication, eventually finding better, cheaper and industrially-viable ways of fabricating nanoscale objects and nanodevices is the main aim of the International Plasma Nanoscience Network. The concept of (plasma-controlled) determinism is central to our research endeavors. Here, we present the latest advances in experimental and computational research on deterministic plasma-aided nanofabrication and processing of various nanoscale objects of different dimensionality, sizes, shapes, crystalline structure, elemental composition, arrangement and ordering in nanoarrays, etc. [1]. The benefits and advantages of using low-temperature (non-equilibrium and thermal) plasma environments are revealed and the relevant processes optimized to meet the continuously rising demands of nanotechnology [1]. [1] K. Ostrikov, IEEE Tran. Plasma Sci. 35, 127 (2007); K. Ostrikov, A. B. Murphy, J. Phys D.: Appl. Phys. 40, 2223 (2007) [Preview Abstract] |
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SRP1.00038: PLASMA PROPULSION AND AERODYNAMICS |
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SRP1.00039: Structure of stationary shock waves in weakly ionized gas D.J. Drake, B. Rodgers, S. Popovic, L. Vuskovic We performed detailed laboratory measurements of the excited-species population distributions across stationary shock waves in weakly ionized gas. Ionized gas was sustained in a cylindrical cavity integrated in the supersonic microwave flowing afterglow apparatus. An oblique solid body was suppressing the flow to generate a stationary acoustic shock wave. A cylindrical cavity was used to sustain a discharge in air, argon, and Martian air in the pressure range of 100-600 Pa. Argon is also a significant constituent of terrestrial and Martian air. Excited state populations of argon were measured using emission and absorption spectroscopy for the absolute intensities of the (4p-4s) spectral lines. Comparison was made between the populations in a model free flow and across the shock front. Oblique shock parameters were evaluated exactly for the given model geometry. Obtained data on the shock wave structure were compared with available shock-wave computational models. [Preview Abstract] |
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SRP1.00040: Schlieren observation of vortex flow structures in asymmetric dielectric barrier discharges Dmitry Opaits, Alexandre Likhanskii, Gabriele Neretti, Sohail Zaidi, Mikhail Shneider, Sergey Macheret, Richard Miles Asymmetric DBD plasma actuator for flow control has been studied both numerically and experimentally. A comprehensive kinetic model for asymmetric DBD actuators in air has been developed. A new approach for non-intrusive diagnostic of plasma actuator induced flows in quiescent gas was proposed. The schlieren technique, burst mode of plasma actuator operation, and 2-D fluid numerical model coupled together allowed us to restore the entire two-dimensional unsteady plasma induced flow pattern as well as characteristics of the plasma induced force. A new voltage profile, consisted of nanosecond repetitive pulses added to low-frequency sinusoidal bias voltage, is proposed. Advantages of the new voltage profile have been demonstrated experimentally. Dependences of the DBD operation on bias voltage, pulse voltage and repetition rate have been investigated for both polarities of the pulses. Significance of the surface charge has been demonstrated. [Preview Abstract] |
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SRP1.00041: LASER MEDIA, KINETICS, PROCESSES |
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SRP1.00042: X-ray laser spectroscopy of heavy ions at the GSI, Darmstadt, Germany Alexander Mayr, Rustam Berezov, Joachim Jacoby, Thomas Kuehl, Olga Rosmej, Bernd Sicherl, Daniel Urescu, Bernhard Zielbauer, Daniel Zimmer As a branch of the PHELIX laser project at GSI, a 13.9 nm x-ray laser is developed. Using this x-ray laser, spectroscopic measurements on highly-charged heavy ions will be made. At GSI, ions up to uranium can be provided in specific charge states by the fragment separator FRS and then stored and cooled in the experimental storage ring ESR. The upcoming FAIR facility will also produce many radioactive nuclei. The unique combination of heavy-ion beam and x-ray laser allows the accurate spectroscopic rating of quantum-mechanical states of atomic nuclei and the comparison of this information with theoretical predictions. This will be achieved by the use of lithium-like heavy ions because for these four-body systems the models of quantum electrodynamics give results which are precise enough. The paper will give information about the realisation of the experimental concept, the current state of the x-ray laser setup and the development of the corresponding detection systems. [Preview Abstract] |
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SRP1.00043: KrF Laser Amplification in the Multi-Staged Electra Facility J. Giuliani, M. Wolford, M. Myers, J. Sethian, F. Hegeler, P. Burns, R. Jaynes Electra is a rep-rated, e-beam pumped KrF laser system at the Naval Research Laboratory investigating the physics and technology required for inertial fusion energy. To date the main cell has operated as an oscillator and achieved $\sim $1.5 kW at 5 Hz for 2000 shots and at 2.5 Hz for over 22,000 shots. The next step is to convert Electra into an amplifier system. A commercial KrF discharge oscillator will provide the initiating laser pulse. This pulse is then sequentially amplified through a preamp in a single pass, followed by a double pass through the main amp. The final system output laser energy depends upon the e-beam pumping power in each amp. To examine this dependency the KrF kinetics/laser simulation code Orestes has been used to follow the growth of the low energy oscillator pulse as it sequentially propagates through the two amplifiers. In addition to the energy, the final output laser pulse shape is a complex product of the amplification and timing between the multiplexed laser pulses and the e-beam pulsed power. Simulations for the preamp have demonstrated partial agreement with the profiles and provide a test of the molecular/plasma kinetic processes used in Orestes. [Preview Abstract] |
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SRP1.00044: INDUCTIVELY COUPLED PLASMAS |
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SRP1.00045: Measurement of radial density of Ar metastables in an inductively coupled plasma in Ar/O$_2$ Yuichiro Hayashi, Satoshi Hirao, Toshiaki Makabe O$_2$ plasma is used for ashing and trimming of the resist in semiconductor production processes, and for the surface modification of metals and polymers. In these processes atomic O radicals play important roles. It is reported that the density of atomic metastables increase in Ar/O$_2$ mixture as compared with that in pure O$_2$ in CCP [1]. We measured the radial profile of the density of Ar metastables (1s3, 1s5) and the temperature in an inductively coupled plasma at 13.56 MHz in Ar/O$_2$ as a function of admixture O$_2$ by using laser absorption spectroscopy. The average densities of metastable Ar are $2 \times 10^{10}$ cm$^{-3}$ (1s3) and $10^{11}$ cm$^{-3}$ (1s5) for 0-20\% O$_2$ fraction, and have the peak at 5-10\%. The temperatures are 2000 K (1s3) and 1600 K (1s5) and are heighest at 10\%. \newline \newline [1] T. Kitajima, T. Nakano, and T. Makabe, Appl. Phys. Lett., \textbf{88}, 091501 (2006). [Preview Abstract] |
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SRP1.00046: Space- and Time-Resolved E-H Transition by using ICCD Camera in an Inductively Coupled Plasma in Ar Satoshi Hirao, Yuichiro Hayashi, Toshiaki Makabe Inductively coupled plasma (ICP) has been widely used as a high density plasma source in various applications. ICP has two operating modes. One is a low density (capacitively coupled) E- mode sustained by the static electric field between terminals of the induction coil. The other is a high-density (inductively coupled) H-mode sustained by the induced electromagnetic field. It is well known that there is an E-H transition in ICP, however the details of this phenomenon are not well-known. In our previous work, we experimentally studied the ICP in Ar by using ICCD camera located at the side of the reactor, and observed the E-H transition by the line-integrated time-resolved emission images. In the present study, we set the ICCD camera on the top of the reactor to measure the 2D-t plasma structure at the coil plane. We mainly focus on the emission from Ar(2p1) as a probe of high energy electrons, and discuss the behavior of plasma during E-H transition. [Preview Abstract] |
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SRP1.00047: Kinetics of charged particles and nonlocal control of plasma properties in a pulsed rf icp in argon-oxygen mixtures J.C. Blessington, V.I. Demidov, M.E. Koepke, C.A. DeJoseph, Jr. Previously [1], we showed that a simple, three-level model could explain the rapid growth of charge particles following application of rf power to a noble gas. In this work we show experimentally that addition of a small amount of oxygen can significantly reduce the rate of growth of charged particle density, indicating the simple three-level model is no longer applicable. Even in this case, the positive ion density (measured by probes) reaches a stationary value much faster than the atomic oxygen density (estimated from plasma emission). Thus, by changing the duration of the rf pulse, the ratio of fast electron production, by the reaction O + O$^{-}\to $ O$_{2}$ + e (3.6 eV), compared to the ambipolar flux of positive ions to the discharge walls, can be controlled. This effect can be used for nonlocal regulation of plasma properties [2]. \newline \newline [1] V. I. Demidov, C. A. DeJoseph, Jr. et all, PSST, 2004, 13, 600. \newline [2] C. A. DeJoseph, Jr. et all, Phys. Plasmas, 2007, 14, 057101. [Preview Abstract] |
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SRP1.00048: Fluid model for a Cl$_{2}$/Ar inductively coupled discharge Emilie Despiau-Pujo, Pascal Chabert, David B. Graves III-V compounds such as GaAs, InP or GaN-based materials are widely used for photonics and optoelectronic applications, especially in the telecommunications and light detection industries. Although many problems remain to be understood, inductively coupled discharges seem to be very promising to etch such materials, using Cl$_{2}$/Ar, Cl$_{2}$/N$_{2}$ and Cl$_{2}$/H$_{2}$ gas chemistries. Hsu et al. [1] developed a 2D-fluid model to calculate the plasma parameters along with the neutral radical densities and profiles for purely inductive discharges in Ar/O$_{2}$ and Ar/O$_{2}$/Cl$_{2}$ mixtures. The model couples plasma electrodynamics to neutral chemistry and transport, under the assumption of quasi-neutrality. Power deposited into electrons comes from inductive coupling from an external coil. We have used this model to investigate Cl$_{2}$/Ar chemistries and get information about the electron density and temperature, composition of the ion wall flux and radical densities. Some comparisons with experimental measurements are reported. The addition of capacitive coupling and the study, in the presence of negative ions, of the transitions from E to H modes are under investigation. [1] Hsu et al, J. Phys. D: Appl. Phys. 39 (2006) 3272-3284 [Preview Abstract] |
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SRP1.00049: The effect of a planar antenna on a ferromagnetic core ICP Jin Young Bang, Sung Won Cho, Chin Wook Chung A side type ferrite inductively coupled plasmas (ICPs) with high efficiency and low voltage suitable for next generation processing was recently developed [1]. In this ICP, the plasma density at edge of the chamber is higher than center of the chamber because the region where the plasma generation is localized at the edge of the chamber. To control plasma uniformity in various environments, an additional planar antenna on the top of the chamber was installed at the center to increase the center density and the effect of the additional antenna was analyzed. \newline \newline [1] K. H. Lee, Y. K. Lee, S. W. Lee, C.W. Chung, Gases Electron Conference 2006. [Preview Abstract] |
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SRP1.00050: Development of a novel Inductive coupled plasma source Hyong-ho Nam, Hyo-chang Lee, Chin-wook Chung To improve plasma uniformity, a three-turn cross antenna was developed. The three-turn cross antenna has low inductance and low antenna voltage. The antenna voltage is 227V at 100W(13.56MHz) and at argon 10 mTorr while it is 1200 V at a single turn antenna. Plasma density is 10$^{11}\sim$10$^{12}$cm$^{-3}$ in the range of 5mTorr to 20mTorr and 100W to 600W. Plasma azimuthal asymmetry is below 5{\%}. This antenna is expected to be suitable for next generation plasma processing. [Preview Abstract] |
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SRP1.00051: Investigation of an RF ICP J. Wiechula, M. Iberler, J. Jacoby, C. Teske In the present study, an experiment with an electrode less inductively coupled plasma (ICP) is under investigation. The main section of the experimental setup is a discharge tube of glass wrapped with a cylindrical induction coil. The RF power is coupled into the plasma by transformer action. Driven at a fixed frequency of 13.56MHz the generator used in this experiment can deliver up to 10kW of RF power. For diagnostic purposes Ar and He is used as a working gas. A main interest of this experiment is the influence of the coil geometry on the coupling efficiency between the external circuitry and the plasma. Therefore, measurements of the electrical parameters are performed to determine the coupling efficiency and monitor the capacitive-to-inductive transition, which occurs at higher power levels. The electron temperature of the discharge plasma is measured by spectroscopic means where else the electron density is determined using a langmuir probe. Comparing these results with the electrical measurements will enable us to achieve further insights into the relation between plasma parameters and the electrical characteristics of the driving circuitry. [Preview Abstract] |
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SRP1.00052: BIOLOGICAL AND EMERGING APPLICATIONS OF PLASMAS |
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SRP1.00053: Chemical modification and its evaluation of CNT-based bio-nanosensor by plasma activation technique T. Hirata, S. Amiya, M. Akiya, O. Takei, T. Sakai, T. Nakamura, J. Totake, T. Yamamoto, R. Hatakeyama In order to chemically modify single-walled carbon nanotubes (SWCNTs), plasma ion irradiation (plasma activation) is demonstrated on a bio-nanosensor based on poly[ethylene glycol]-grafted SWCNTs (PEG-SWCNTs) network. The PEG-SWNTs network is placed between the electrodes in the sensor-chip using a micropipet. The experimental apparatus for the plasma-activation is a magnetron-type plasma generater. The gas used for the production of carboxyl (COOH) groups in order to the immobilization of living body materials such as antibody or DNA is atmospheric air. PEG-SWNTs are synthesized by azo-PEG (initiators). According to the XPS analysis, peaks which correspond to COOH groups are observed, the ratio of the COOH peak to all peak areas has increased to 34 times that before ion irradiation. In addition, evaluation of the bio-nanosensor for a characteristic response to bovine serum albumin (BSA) [or oligonucleotides] revealed an increase in impedance between the electrodes due to BSA/anti-BSA binding (or oligonucleotides hybridization) after injection. The results of this study indicate that this bio-nanosensor reacts with a quick response time (ca. 60 s). [Preview Abstract] |
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SRP1.00054: ENVIRONMENTAL APPLICATIONS |
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SRP1.00055: Evaluation of Decomposition Treatment for Halogenized Compounds by Acceleration of Electrons from Carbon Nanotubes Michiteru Yamaura, Shigeaki Uchida, Masayuki Fujita, Masahiro Nakatsuka, Chiyoe Yamanaka A novel decomposition treatment for halogenized compounds using a carbon nanotube (CNT) electron source is proposed [1]. It is observed that high concentrations of chlorophenols can be significantly decreased by using a CNT electron source. The concentration is reduced to a maximum level of less than 1/1000 after only a few minutes of treatment. The input energy required for 1 g of chlorophenol is 46 J when the injection power is 0.5 W. The input energy is only 1/161 times lesser than that required for the treatment using barrier discharge. The proposed treatment using CNTs has a high efficiency because the input energy is provided only by the accelerated electrons. A harmless and high-efficiency decomposition treatment for halogenized compounds using an electron source with carbon nanotubes is discussed. \newline [1] M.Yamaura, et al. Chem. Phys. Lett \textbf{435}, 148 (2007). [Preview Abstract] |
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SRP1.00056: Development of simultaneous decomposition technique of diesel particulate materials and nitric oxides using dielectric barrier discharge Yukihiko Yamagata, Yozo Kawagashira, Katsunori Muraoka Recently, we have proposed a new decomposition technique for environmentally hazardous materials with very low concentration, and successfully decomposed volatile organic compounds. This is based on the combination of dielectric barrier discharge (DBD) with condensation/localization technique. In order to apply this technique to an after treatment of diesel exhaust gas, simultaneous decomposition of diesel particulate materials (DPMs) and nitric oxides was demonstrated. DPMs were collected in a reactor using an electrostatic precipitation operated by a negative corona discharge. At DC 5 kV more than 95{\%} of DPMs were continuously collected for 60 min. Subsequently, the collected DPMs were decomposed in a model gas including NO molecules by a DBD. In the presence of DPMs, a large amount of NO was decomposed compared with that in the absence of DPMs. It is suggested that actual DPMs and NO which acts as the oxidant and reductant, respectively, are decomposed simultaneously and effectively by DBD. [Preview Abstract] |
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