Bulletin of the American Physical Society
66th Annual Gaseous Electronics Conference
Volume 58, Number 8
Monday–Friday, September 30–October 4 2013; Princeton, New Jersey
Session AM1: Workshop on Plasma Surface Interaction: From Fusion to Semiconductor Processing |
Hide Abstracts |
Chair: Yevgeny Raitses; Vincent Donnelly; David Graves; Greg DeTemmerman, PPPL; University of Houston; UC Berkeley; FOM Institute DIFFER Room: Ballroom I |
Monday, September 30, 2013 8:00AM - 8:05AM |
AM1.00001: Welcome Y. Raitses |
Monday, September 30, 2013 8:05AM - 8:35AM |
AM1.00002: Challenges of Low Temperature Plasma-Surface Interactions David Graves Low temperature plasma-surface interactions are characterized by complex, coupled interactions of chemical, physical and material phenomena interacting over a wide range of time and length scales. Intriguingly, some of the same kinds of challenges exist in non-low temperature plasma applications, including fusion-wall interactions. In this talk, I will review some of the history of low temperature plasma-surface studies and suggest some grand challenges in this interdisciplinary field. Examples will be presented from plasma-semiconductor surface interactions with an industrial focus. The latest applications of low temperature plasma involve plasma-soft material interactions, in some cases including the presence of water. The developing field of low temperature plasma medicine includes plasma-living tissue interactions. Some of the unique challenges posed by this new field will be briefly addressed. [Preview Abstract] |
Monday, September 30, 2013 8:35AM - 9:05AM |
AM1.00003: The Science and Technology Challenges of the Plasma-Material Interface for Magnetic Fusion Energy Dennis Whyte The boundary plasma and plasma-material interactions of magnetic fusion devices are reviewed. The boundary of magnetic confinement devices, from the high-temperature, collisionless pedestal through to the surrounding surfaces and the nearby cold high-density collisional plasmas, encompasses an enormous range of plasma and material physics, and their integrated coupling. Due to fundamental limits of material response the boundary will largely define the viability of future large MFE experiments (ITER) and reactors (e.g. ARIES designs). The fusion community faces an enormous knowledge deficit in stepping from present devices, and even ITER, towards fusion devices typical of that required for efficient energy production. This deficit will be bridged by improving our fundamental science understanding of this complex interface region. The research activities and gaps are reviewed and organized to three major axes of challenges: power density, plasma duration, and material temperature. The boundary can also be considered a multi-scale system of coupled plasma and material science regulated through the non-linear interface of the sheath. Measurement, theory and modeling across these scales are reviewed, with a particular emphasis on establishing the use dimensionless parameters to understand this complex system. Proposed technology and science innovations towards solving the PMI/boundary challenges will be examined. [Preview Abstract] |
Monday, September 30, 2013 9:05AM - 9:35AM |
AM1.00004: Plasma Surface Interactions at a ``Spinning Wall'' Vincent M. Donnelly Reactions of neutral species on surfaces immersed in plasmas have been recognized for many years to be important in affecting the chemistry of plasma processes such as plasma etching and chemical vapor deposition. The reactions of radicals on the surfaces of chamber walls and substrates are a sink for radicals and a source of larger product species. This talk will discuss a method for studying these processes in near-real-time. The surface of a rapidly rotating cylindrical substrate placed between the plasma chamber wall and a differentially pumped diagnostic chamber is continuously exposed to the plasma and then analyzed. Products desorbing from the surface a few milliseconds after exposure to the plasma are detected by line-of-sight mass spectrometry, while the surface is monitored with Auger electron spectroscopy. Kinetics of surface reactions can be extracted from an analysis of the signal intensities as a function of substrate rotation frequency. Examples of recombination of Cl and O atoms in chlorine and oxygen plasmas will be discussed. Possible applications of this method to studies plasma-surface interactions under harsher conditions, including at the edge of magnetic fusion devices, will be discussed. [Preview Abstract] |
Monday, September 30, 2013 9:35AM - 9:50AM |
AM1.00005: Coffee Break
|
Monday, September 30, 2013 9:50AM - 10:20AM |
AM1.00006: Determining atom and radical surface recombination coefficients in low-pressure plasmas Jean-Paul Booth In many low-pressure plasma processing applications (such as plasma etching), the dominant loss process for reactive atoms and free radicals is recombination at the reactor walls. This process is usually quantified by a phenomenological surface reaction coefficient, $\beta $, varying between 0 and 1, which is a crucial parameter for plasma modelling. As no reliable ab-initio theory exists to estimate the value of $\beta $ for real surfaces, and as it may vary depending on the prevalent conditions, it must be measured in-situ. The simplest and most widespread technique is to determine the lifetime of the species in question in the afterglow of a pulsed plasma. The species density can be measured as a function of time using various methods including laser-induced fluorescence and time-resolved optical emission spectroscopy, and the coefficient is then derived using a diffusion model. This has been applied to many atoms (H, O, Cl, \textellipsis ) and free radicals (CF, CF$_{2}$, \textellipsis .) This method necessarily assumes that the coefficient is unchanged in the afterglow, which may be questionable. Furthermore, if the gas temperature in the steady state plasma is significantly above that of the walls, the temperature will vary in the afterglow period, and may even cause gas convection, making analysis difficult. An alternative is to measure the density gradient adjacent to the surface in the steady state. The pros and cons of these methods will be discussed with examples of measurements. [Preview Abstract] |
Monday, September 30, 2013 10:20AM - 10:50AM |
AM1.00007: Low Temperature Plasma Surface Interactions: Atomic Layer Etching And Atmospheric Pressure Plasma Jet Modification Of Biomaterials* Gottlieb Oehrlein Control of plasma-surface interactions is essential for successful application of low temperature plasma to materials processing. We review work performed in our laboratory in two areas: First, low pressure plasma surface interaction mechanisms aimed at achieving atomic precision in etching materials in the semiconductor industry. We discuss sequential reactions of surface passivation followed by directional low energy ion attack for ``volatile product'' removal to establish for what conditions self-limiting behavior required for Atomic Layer Etching (ALE) can be established using prototypical SiO$_{2}$ --Si/fluorocarbon-Ar materials/etching systems. Second, studies of plasma-surface interactions related to application of a non-equilibrium atmospheric pressure plasma jet (APPJ) for modification of biomaterials are discussed. Changes in surface chemistry/biological activity of lipopolysaccharide (LPS) exposed to the APPJ plume/effluent in a controlled environment are reviewed. The results clarify how jet chemistry and interactions of plasma with the environment impact the consequences of APPJ-biomaterial-surface interactions. *Based on collaborations with D. Metzler, S. Engelmann, R. Bruce, E. Joseph, E. Bartis, C. Hart, Q.-Y. Yang, J. Seog, T.-Y. Chung, H.-W. Chang, and D.B. Graves. We gratefully acknowledge funding from US Department of Energy (DE-SC0005105; DE-SC0001939) and National Science Foundation (CBET-1134273; PHY-1004256). [Preview Abstract] |
Monday, September 30, 2013 10:50AM - 11:20AM |
AM1.00008: Plasma-surface interactions under extreme conditions: challenges and opportunities Gregory De Temmerman In a fusion reactor, power from the hot core plasma has to be exhausted by the plasma-facing components which are exposed to extreme heat (\textgreater 10MW.m$^{-2})$ and particle fluxes (up to 10$^{24}$m$^{-2}$s$^{-1}$ or 1.6x10$^{5}$A.m$^{-2})$- orders of magnitude higher than in conventional plasma processing technique. Much of the fundamentals of the materials behaviour under such extreme ion irradiation conditions is not yet fully understood and limits our ability to develop materials able to survive those conditions. Combining a high efficiency plasma source and a strong magnetic field, linear plasma devices (LPD) allow to reproduce and even exceed the conditions expected in a fusion reactor. Owing to the good access to the plasma-material interaction zone for diagnostics and sample manipulation, those devices allow advanced experiments necessary to the fundamental understanding of plasma-surface interactions. In addition, the ion flux is such that a direct comparison with MD modelling, traditionally hampered by the large gap between fluxes in model and experiments, is now possible. This presentation will give an overview of the research performed to understand materials behaviour under extreme conditions with a focus on irradiation-driven modifications of metals. In parallel, the non-equilibrium conditions induced by the surface bombardment by extreme fluxes of low-energy particles open a novel route for the synthesis of advanced nanostructured materials, an illustration of which will be given. [Preview Abstract] |
Monday, September 30, 2013 11:20AM - 11:50AM |
AM1.00009: Understanding plasma facing surfaces in magnetic fusion devices C.H. Skinner, A.M. Capece, B.E. Koel, J.P. Roszell The plasma-material interface is recognized to be the most critical challenge in the realization of fusion energy. Liquid metals offer a self-healing, renewable interface that bypasses present issues with solid, neutron-damaged materials such as tungsten. Lithium in particular has dramatically improved plasma performance in many tokamaks through a reduction of hydrogen recycling. However the detailed chemical composition and properties of the top few nm that interact with the plasma are often obscure. Surface analysis has proven to be a key tool in semiconductor processing and a new laboratory has been established at PPPL to apply surface science techniques to plasma facing materials. We have shown that lithiated PFC surfaces in tokamaks will likely be oxidized during the intershot interval. Present work is focused on deuterium uptake of solid and liquid metals for plasma density control and sub-micron scale wetting of liquid metals on their substrates. The long-term goal is to provide a material database for designing liquid metal plasma facing components for tokamaks such as National Spherical Torus Experiment-Upgrade (NSTX-U) and Fusion Nuclear Science Facility-ST (FNSF-ST). [Preview Abstract] |
Monday, September 30, 2013 11:50AM - 12:50PM |
AM1.00010: Lunch
|
Monday, September 30, 2013 12:50PM - 1:20PM |
AM1.00011: Interplay between discharge physics, gas phase chemistry and surface processes in hydrocarbon plasmas Khaled Hassouni In this paper we present two examples that illustrate two different contexts of the interplay between plasma-surface interaction process and discharge physics and gas phase chemistry in hydrocarbon discharges. In the first example we address the case of diamond deposition processes and illustrate how a detailed investigation of the discharge physics, collisional processes and transport phenomena in the plasma phase make possible to accurately predict the key local-parameters, i.e., species density at the growing substrate, as function of the macroscopic process parameters, thus allowing for a precise control of diamond deposition process. In the second example, we illustrate how the interaction between a rare gas pristine discharge and carbon (graphite) electrode induce a dramatic change on the discharge nature, i.e., composition, ionization kinetics, charge equilibrium, etc., through molecular growth and clustering processes, solid particle formation and dusty plasma generation.\\[4pt] Work done in collaboration with Alix Gicquel, Francois Silva, Armelle Michau, Guillaume Lombardi, Xavier Bonnin, Xavier Duten, CNRS, Universite Paris 13. [Preview Abstract] |
Monday, September 30, 2013 1:20PM - 1:50PM |
AM1.00012: Plasma-Surface Interaction in Presence of Intense Electron Emission from Walls I.D. Kaganovich, E.A. Startsev, Y. Raitses, H. Wang, M.D. Campanell, A.V. Khrabrov, A.N. Andronov, A.S. Smirnov, D. Sydorenko, V.I. Demidov The plasma-surface interaction in presence of strong thermionic or secondary electron emission has been studied theoretically and experimentally both as a basic phenomenon and in relation to numerous plasma applications such as, divertor plasma, particle accelerators, surface discharges, plasma thrusters and plasma processing [1-3]. Secondary electron emission (SEE) from walls can be induced by electron or ion impact. The SEE can greatly alter the plasma-wall interaction and modify the whole structure of the plasma and its stability. A review of present theoretical models and experimental methods of investigating emission properties of different materials will be given. We also review a recently proposed effect that the reflectivity of very low energy electrons from solid surface approaches unity in the limit of zero electron energy [2]. We report on recent experimental and particle-in-cell simulation studies on plasma-surface interaction in presence of electron emission [3,4]. \\[4pt] [1] J. Cazaux. J. Appl. Phys. 111 064903 (2012). [2] R. Cimino, I.R. Collins. Appl. Surface Scie. \textbf{235}, 231 (2004). [3] Y. Raitses, et al, IEEE Trans. on Plasma Scie. \textbf{39}, 995 (2011). [4] M. D. Campanell, et al, Phys. Rev. Lett. \textbf{108}, 235001 and 255001 (2012). [Preview Abstract] |
Monday, September 30, 2013 1:50PM - 2:20PM |
AM1.00013: Behaviors of Hydrogen, Helium and their Synergy in Tungsten Guang-Hong Lu Tungsten (W) is one of the most promising plasma facing material (PFM) candidates for fusion energy systems. However, effects of hydrogen (H) isotopes and helium (He) particularly their retention and blistering in W remain to be key issues that need to be addressed. In this talk, we will discuss the effects of H and He in W in terms of the physical mechanism revealed by simulations in combination with related experiments. Via modelling and simulation in different scales, the nucleation and growth mechanism of H bubbles in W have been investigated. First-principles calculations show that a vacancy induces collective H binding on its internal surface. Further calculations suggest a cascading effect of H bubble growth in W. Based on such vacancy trapping mechanism, He as well as other inert gas elements such as neon and argon can suppress the H bubble nucleation and blistering, which is confirmed by the experimental observation. Difference between H and He behaviors and their synergy in W due to their different electronic structure will be emphasized, from which we can further consider the actual complicated H/He interaction with W and their effects on (mechanical) properties of W in future fusion reactors. [Preview Abstract] |
Monday, September 30, 2013 2:20PM - 2:35PM |
AM1.00014: Coffee Break
|
Monday, September 30, 2013 2:35PM - 3:05PM |
AM1.00015: Challenges in Modeling of the Plasma-Material Interface Predrag Krstic, Fred Meyer, Jean Paul Allain Plasma-Material Interface mixes materials of the two worlds, creating a new entity, a dynamical surface, which communicates between the two and represent one of the most challenging areas of multidisciplinary science, with many fundamental processes and synergies. How to build an integrated theoretical-experimental approach? Without mutual validation of experiment and theory chances very slim to have believable results? The outreach of the PMI science modeling at the fusion plasma facilities is illustrated by the significant step forward in understanding achieved recently by the quantum-classical modeling of the lithiated carbon surfaces irradiated by deuterium, showing surprisingly large role of oxygen in the deuterium retention and erosion chemistry. The plasma-facing walls of the next-generation fusion reactors will be exposed to high fluxes of neutrons and plasma-particles and will operate at high temperatures for thermodynamic efficiency. To this end we have been studying the evolution dynamics of vacancies and interstitials to the saturated dpa doses of tungsten surfaces bombarded by self-atoms, as well as the plasma-surface interactions of the damaged surfaces (erosion, hydrogen and helium uptake and fuzz formation). [Preview Abstract] |
Monday, September 30, 2013 3:05PM - 3:35PM |
AM1.00016: Plasma-Surface Interactions in Electric Thrusters Dan Goebel Of critical importance in electric propulsion missions in space is thruster life, which is determined to a large extent by wall erosion from plasma-materials interactions. While the plasmas generated in different thrusters vary, the particle fluxes, energies and temperatures in contact with the walls are somewhat similar. The erosion rates are then determined by details of materials, incident angles, etc. In ion and Hall thrusters commonly used today, for example, cathode life is determined by low energy ($\le $100 eV) Xe ion erosion of the cathode electrodes. Erosion of ion thruster accelerator grids is dominated by charge exchange ion bombardment with energies of 200 to 400 V. The incident angle of these ions is near normal, but the sputtered particles are ejected with a butterfly distribution that directs particles along the thruster axis and causes build up of material on the upstream and downstream surfaces. In Hall thrusters, the plasma materials interactions at the wall are complicated because the walls are typically ceramic and selected for a low secondary electron yield for thruster performance. The erosion rates at the wall vary due to non-uniform plasma contact with the surface causing grooves and surface changes. These effects will be discussed for various thrusters. [Preview Abstract] |
Monday, September 30, 2013 3:35PM - 4:05PM |
AM1.00017: Atmospheric Pressure Plasmas Incident onto Thin Liquid Layers Wei Tian, Seth Norberg, Natalia Yu. Babaeva, Mark J. Kushner The interaction of plasmas with liquids has increasing importance in advanced manufacturing and biomedical applications. Sustaining atmospheric pressure plasmas \textit{on liquids} (as opposed to \textit{in liquids}) can increase the chemical activity of the liquid by transferring more easily produced reactive species from the gas phase into the liquid. Often the intent is to treat the surface under the liquid layer, as in plasma medicine. The liquid then acts as a filter which modifies the fluxes of reactive species prior to reaching the underlying surface. The liquid in turn influences the plasma by evaporation which produces a saturated layer of, for example, water vapor above the liquid surface, or by the shape of liquid covered wounds and the dielectric properties of the liquid. Direct plasma exposure (e.g., a dielectric barrier discharge) enables intersection of ion and UV/VUV fluxes with the liquid surface whereas many remote plasma jets typically do not. This increases the rate of hydronium (H$_{\mathrm{3}}$O$^{\mathrm{+}})$ production which affects pH. In this paper, results from a computational investigation on the dynamics of atmospheric pressure plasmas intersecting thin water layers having dissolved gases and proteins will be discussed. Examples are taken from DBD and plasma jet exposure of water layers over a tissue-like dielectric, and plasmas sustained in bubbles in water. The mutual interaction of the plasma and liquid will be discussed based on radiation and ion transport into the water, evaporation, and transport and conversion of plasma produced reactivity through the water layer. [Preview Abstract] |
Monday, September 30, 2013 4:05PM - 4:50PM |
AM1.00018: Roundtable Discussion Moderators: Michael A. Lieberman of UC Berkley and Russel Doerner of UC San Diego [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700