Bulletin of the American Physical Society
67th Annual Gaseous Electronics Conference
Volume 59, Number 16
Sunday–Friday, November 2–7, 2014; Raleigh, North Carolina
Session LW1: Plasma Diagnostics III |
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Chair: Pascal Chabert, Laboratoire de Physique des Plasmas Room: State EF |
Wednesday, November 5, 2014 3:30PM - 3:45PM |
LW1.00001: Inductively-coupled plasmas in pure Cl, Oand mixtures: measurements of atoms, Cl$_{\mathrm{x}}$O$_{\mathrm{y}}$and electron densities Micka\"el Foucher, Emile Carbone, Jean-Paul Booth, Pascal Chabert Inductively-coupled plasmas in Cl/O(often with HBr) are widely used in the microelectronics industry for the etching of silicon CMOS gates. Many simulations describing these plasmas (global and 2-dimensional fluid models such as HPEM) have been developed but experimental validation is sparse. This paper addresses this gap with a large quantity of experimental data in plasmas of Cl, Oand their mixtures. The plasma is excited by a 4-turn planar coil powered at 13.56 MHz through a dielectric window, and contained in a cylindrical anodized aluminium reactor (55 cm diameter, 10 cm high). Electron densities were measured with a microwave hairpin resonator. In all cases the electron density passes through a maximum with pressure. The ground-state O and Cl atom density was measured by Two-Photon Absorption Laser-Induced Fluorescence (TALIF) combined with specific absolute calibration techniques. Broad-band absorption spectroscopy was used to measure the density of Cland vibrationally excited Omolecules, excited state Cl atoms and a range of oxychlorides products. To our knowledge this is the first time that these oxychloride densities and vibrationally excited molecules have been measured in low-pressure plasmas. [Preview Abstract] |
Wednesday, November 5, 2014 3:45PM - 4:00PM |
LW1.00002: Time evolution of spatial RF field profiles in a 100 MHz reactor Barton Lane, Ikuo Sawada, Peter Ventzek, Colin Campbell, Akira Koshiishi We report here on time and space resolved magnetic and electric field strength measurements in a 100 MHz reactor. The reactor studied is a test bed reactor with a geometry which approximately mimics commercial reactors for semiconductor manufacturing. The magnetic fields were captured using a B-dot probe fashioned after the work of Miller et al. [1] Time traces at different radial locations are compared using time traces from a fixed pickup probe mounted on the VHF feed in order to obtain magnetic field profiles as a function of radius at different values of the VHF phase. The presence of standing waves and propagating waves are clearly seen. A rapid increase and collapse of the magnetic field at the core of the plasma takes place on a nsec time scale showing the physical origin of the higher harmonic waves seen in previous studies. The profiles show the effect of the non-linear evolution of the wave. The data is presented as an animated sequence of plots of the field strength vs radius. A double dipole probe was also used to measure the vertical component of the VHF field. These measurements confirm the picture given by the B dot probe.\\[4pt] [1] Miller, Barnat, Hebner, Paterson, Holland, Plasma Sources Sci. Tech. \textbf{15} (2006)889-899. [Preview Abstract] |
Wednesday, November 5, 2014 4:00PM - 4:15PM |
LW1.00003: Low pressure characteristics of the multipole resonance probe Ralf Peter Brinkmann, Jens Oberrath The term ``Active plasma resonance spectroscopy'' (APRS) denotes a class of related techniques which utilize, for diagnostic purposes, the natural ability of plasmas to resonate on or near the electron plasma frequency $\omega_{\rm pe}$. The basic idea dates back to the early days of discharge physics but has recently found renewed interest as an approach to industry-compatible plasma diagnostics: A radio frequent signal (in the GHz range) is coupled into the plasma via an antenna or probe, the spectral response is recorded (with the same or another antenna or probe), and a mathematical model is used to determine plasma parameters like the electron density or the electron temperature. When the method is applied to low pressure plasmas (of a few {\rm Pa} and lower), kinetic effects must be accounted for in the mathematical model. This contribution studies a particular realization of the APRS scheme, the geometrically and electrically symmetric Multipole Resonance Probe (MRP). It is shown that the resonances of the MRP exhibit a residual damping in the limit $p\to 0$ which cannot be explained by Ohmic dissipation but only by kinetic effects. [Preview Abstract] |
(Author Not Attending)
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LW1.00004: Diagnostics of Rotational Temperature and Mean Electron Energy Distribution of DC Glow Discharge Using Spectral Image Processing Daisuke Shimizu, Ryo Sasamoto, Takao Matsumoto, Yasuji Izawa, Kiyoto Nishijima The non-thermal plasma has been used in various application fields of manufacturing industry such as surface reforming, plasma etching, deposited film forming. The gas temperature and electron energy in non-thermal plasma play a key role of production of active species. Therefore, it is essential to understand the properties of non-thermal plasma for effective plasma applications. In this study, the two-dimensional rotational temperature and mean electron energy distribution of DC glow discharge plasma under various air pressures were observed using spectral image processing. Rotational temperature distribution was estimated from the emission intensity ratio of head and tail of 2nd positive system band of N$_{2}$ (0, 2). On the other hand, mean electron energy was estimated from the emission intensity ratio of 2nd positive system band of N$_{2}$ (0, 2) and 1st negative system band of N$_{2}^{+}$ (0, 0). The each spectral images were taken by an ICCD camera with narrow band-path filters respectively. As a result, the dependences of rotational temperature and mean electron energy distribution in DC glow discharge on ambient air pressure were clearly observed using spectral image processing. [Preview Abstract] |
Wednesday, November 5, 2014 4:30PM - 4:45PM |
LW1.00005: Laser Induced Fluorescence of the Iodine Ion William Hargus Iodine (I$_2$) has been considered as a potential electrostatic spacecraft thruster propellant for approximately 2 decades, but has only recently been demonstrated. Energy conversion efficiency appears to be on par with xenon without thruster modification. Intriguingly, performance appears to exceed xenon at high acceleration potentials. As part of a continuing program for the development of non-intrusive plasma diagnostics for advanced plasma spacecraft propulsion, we have identified the I~II $5d^5D^o_4$ state as metastable, and therefore containing a reservoir of excited state ions suitable for laser probing. The $5d^5D^o_4-6p^5P_3$ transition at 695.878~nm is convenient for diode laser excitation with the $5s^5S_2^o-6p^5P_3$ transition at 516.12~nm as an ideal candidate for non-resonant fluorescence collection. We have constructed a Penning type iodine microwave discharge lamp optimized for I~II production for table-top measurements. This work demonstrates I~II laser-induced fluorescence in a representative iodine discharge and will validate our previous theoretical work based on the limited available historical I~II spectral data. [Preview Abstract] |
Wednesday, November 5, 2014 4:45PM - 5:00PM |
LW1.00006: Picosecond-TALIF measurements of atomic oxygen in RF driven atmospheric pressure plasma jets Jerome Bredin, James Dedrick, Kari Niemi, Andrew West, Eric Wagenaars, Timo Gans, Deborah O'Connell Picosecond resolution is required for direct measurements, without assumptions, of radicals under the highly collisional environment of atmospheric pressure. Quenching of two-photon absorption laser induced fluorescence (TALIF) excited states is very efficient and the lifetime of approx. a few ns is in the order of a typical ns laser pulse width. To determine radical densities, challenges include knowing the quenching partners and calculating associated quenching rates to obtain the effective lifetime. Using ps-TALIF (32 ps pulse width) it is possible to resolve the lifetime and therefore avoid quenching rate calculations. Spatially resolved measurements in the plume of an RF atmospheric pressure plasma with O2 and dry air admixtures show that the excited state lifetime and ground state densities decrease at the extremities of the plume due to ambient air diffusion. The lifetime with dry air admixtures is longer than with O2 admixtures as oxygen is a more efficient quencher than nitrogen. Measurements in O2 admixtures show that the lifetimes obtained with ps-TALIF are shorter than those calculated. Consequently, either quenching through plasma produced species and/or three body collisions may play a role. [Preview Abstract] |
Wednesday, November 5, 2014 5:00PM - 5:15PM |
LW1.00007: Spectroscopic diagnostics of dusty plasmas Karim Ouaras The formation of carbon nanoparticles particles in low pressure magnetized hydrocarbon plasmas is investigated using infrared quantum cascade laser absorption spectroscopy (QCLAS), mass spectrometry (MS) and laser extinction spectroscopy (LES). Results showed that dust formation is correlated to the presence of a large amount of large positively charged hydrocarbon ions. Large negative ions or neutral species were not observed. These results, along with a qualitative comparison of diffusion and reaction characteristic, suggest that a positive ion may contribute to the growth of nanoparticles in hydrocarbon magnetized plasmas. Growth of carbon nanoparticles has been widely studied in RF plasma. Our aim is to complete these studies in different discharge system, in which the growth mechanisms may be different. In particular, we focus our work on dipolar ECR microwave discharge. The magnetic field of the plasma source is likely to trap carbon-containing charged particles and then modify the dust growth kinetics. In the present study the combination of these diagnostics gives us the tools to study the kinetics of plasma processes. In this way both qualitative and quantitative characteristics could be obtained. An outstanding role may be attributed to the positive ions in the monitored magnetized plasmas, whereas usually formation of dust is supposed driven by negative ions. In addition, we focus our work in tungsten nanoparticle in particular with LES, this noninvasive technique provide us the tool to follow the dynamics and concentration dust. [Preview Abstract] |
Wednesday, November 5, 2014 5:15PM - 5:30PM |
LW1.00008: Resonance Frequencies of Curling Probe in Plasma: Surface Wave Analysis Ali Arshadi, Ralf Peter Brinkmann Electron density is a crucial characteristic in reactive plasma sources determining the quality of material processing like etching. A recently invented plasma diagnostic probe called curling probe resonates in distinctive frequencies when it is embedded in the wall of the plasma reactor. The excited frequencies are studied for various electron densities. It has been demonstrated that the high-frequency (HF) volume wave resonances and the low-frequency (LF) surface wave (SW) resonances are predictable considering the wave propagation in plasma when it is diffracted on the curling probe. We consider the three dimensional diffraction of incident plane wave by a slot in an infinitely thin perfectly conducting screen located between dielectric and sheath. Our computations for LF resonances were published recently. The results are in a very good agreement with the FDTD analysis. Here it is demonstrated that the LF resonances are based on the SW propagation. We compare our result with the one comes from SW analysis and we prove that the LF resonances are not dependent on the length of probe. We generalized our study to be able to investigate the effect of sheath thickness and electron-neutral collisions which is not possible in the other theoretical and computational methods. [Preview Abstract] |
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