Bulletin of the American Physical Society
60th Gaseous Electronics Conference
Volume 52, Number 9
Tuesday–Friday, October 2–5, 2007; Arlington, Virginia
Session ET1: Plasma-Surface Interactions |
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Chair: Antoine Rousseau, LPTP Room: Doubletree Crystal City Crystal Ballroom A |
Tuesday, October 2, 2007 4:00PM - 4:15PM |
ET1.00001: Student Excellence Award Finalist: Surface recombination study in near real time in Cl$_{2}$ plasmas Joydeep Guha, Vincent M. Donnelly We have started a new approach of studying surface reactions in near real time, in which a hollow section of the reactor wall is rotated at high frequencies between the plasma and differentially pumped diagnostic chambers, thereby periodically exposing the surface to the plasma and diagnostic probes. Surface recombination reactions of Cl atoms on anodized aluminum have been investigated by this technique in chlorine plasmas. Cl$_{2}$ desorption following surface recombination was monitored over a time scale of 0.8 to 38 ms after the surface was exposed to the plasma. Cl recombination probabilities were measured over a wide range of Cl atom flux by varying the plasma pressure and absorbed power. Langmuir-Hinshelwood Cl recombination coefficients ($\gamma _{Cl})$ were measured by extrapolating the desorption flux to t = 0. For 5mTorr 600W Cl$_{2}$ plasma, the desorption flux was 2.7 x 10$^{15}$ cm$^{-2}$s$^{-1 }$at t = 0. $\gamma _{Cl}$ values ranged from 0.01 to 0.08 and were found to increase with increasing power and decrease with increasing total pressure. With plasma on, adsorption of undissociated Cl$_{2}$ competes with Cl adsorption particularly at high pressure and low power. Weakly bound Cl$_{2}$ appears to block adsorption sites on the surface, thereby reducing the recombination probability, as observed. Auger analysis of the surface at different plasma conditions suggests that less than 10{\%} of adsorbed Cl atoms actually participates in surface recombination. [Preview Abstract] |
Tuesday, October 2, 2007 4:15PM - 4:30PM |
ET1.00002: Analysis of plasma-surface interactions during plasma etching by in-situ diagnostics of reactants and reaction products Yoshinori Ueda, Masahiro Yoshida, Koji Eriguchi, Kouichi Ono The incoming ions and neutrals onto substrate surfaces govern the etching characteristics achieved; moreover, the product species, desorbed from the substrate being etched, also play an important role in processing. This paper presents a mechanistic study of plasma etching processes, using in-situ plasma and surface diagnostics of reactants and reaction products, to gain a better understanding of competitive mechanisms that occur during etching. Experiments were performed primarily in an inductively coupled plasma reactor, with emphasis being placed on Si etching with Cl$_{2}$/O$_{2}$ chemistries and on HfO$_{2}$ etching with BCl$_{3}$/Cl$_{2}$/O$_{2}$ chemistries. Optical emission spectroscopy, laser-induced fluorescence spectroscopy, and quadrupole mass spectrometry were employed to observe reactant and product species in the gas phase. Fourier transform infrared absorption spectroscopy was also employed, to observe triatomic and larger molecules of reactants and reaction products in the gas phase and on surfaces; in practice, the gas-phase species was observed by transmission absorption spectroscopy, and the product species such as SiCl$_{x}$ and HfCl$_{x}$ on the surface by reflection absorption spectroscopy. The mechanisms responsible for selective etching of Si over SiO$_{2}$ and of HfO$_{2}$ over Si are discussed based on these observations. [Preview Abstract] |
Tuesday, October 2, 2007 4:30PM - 4:45PM |
ET1.00003: Experimental study and modeling of plasma-polymer interactions Anatoly Napartovich, Yuri Akishev, Mikhail Grushin, Nikolay Dyatko, Igor Kochetov, Nikolay Trushkin, Tran Duc, Francoise Sommer Atmospheric pressure discharges producing high non-thermal plasma were employed for polypropylene (PP) film surface. Two types of discharges were examined: pulse periodic streamer-like discharge in air flow and glow discharge in nitrogen. Water/surface contact angles before and after plasma treatment were measured. A pronounced improvement of surface wettability is observed, and its dependence on plasma exposer is found. This effect is stronger for nitrogen glow discharge processing. Ageing of surface properties proceeds slower after nitrogen plasma treatment. XPS method was implemented to characterize changes in functional groups on polymer interface. The theoretical models were developed for plasma chemistry induced in air by streamer-like discharge and for plasma-surface interactions governed by chemical radicals. Processes of hydrogen abstraction from the surface, secondary reactions with formed active sites, and finally backbone scission are considered. Satisfactory agreement with respect to after treatment composition of functional groups on the surface is achieved between results of XPS measurements and theoretical model predictions. The plasma-surface interaction model provides a solid basis for attacking the ageing problem. [Preview Abstract] |
Tuesday, October 2, 2007 4:45PM - 5:00PM |
ET1.00004: Hydrogen plasma interaction with graphite surface Gilles Cartry, Cedric Thomas, Jean-Marc Layet, Thierry Angot Interaction of hydrogen with graphite surfaces is of great interest for controlled fusion, where carbon material erosion by hydrogen is a key issue. Indeed, tritium retention resulting from carbon redeposition is a safety problem. In this perspective, we study interaction between hydrogen plasma and graphite. We aim to understand erosion mechanisms and identify the role of ions and neutrals. In order to unravel all plasma-surface interaction mechanisms, we associated on a same ultra-high vacuum set-up, an ICP plasma source, an atomic hydrogen source and a hydrogen ion gun. Surface properties were probed with \textit{in-situ} high-resolution electron-energy-loss spectroscopy (HREELS) and with \textit{in-situ} scanning tunneling microscopy (STM). Comparison with DFT calculations leads us to establish the model of H adsorption process. Surface exposition to atomic hydrogen leads to relatively weak adsorption of H atoms. Surface exposition to 300eV H$_{2}^{+}$ ions leads to formation of defects without H adsorption. Subsequent H exposition shows the presence of strongly bonded H atoms. Plasma expositions reveal the presence of strongly bonded H atoms. [Preview Abstract] |
Tuesday, October 2, 2007 5:00PM - 5:30PM |
ET1.00005: Plasma-Surface Interactions With Advanced Polymers For Nanoscale Patterning Of Materials Invited Speaker: Photolithography and plasma-based transfer of resist patterns to produce devices are the basis of the information technology, and other technologies where patterned films or substrates are needed. The most highly developed is the silicon integrated circuit industry, which employs plasma{\-}based etching to produce device features with precisely controlled nanoscale dimensions. Given the tremendous success of this technology, it is surprising that one of the least understood elements of this approach remains the interaction of the plasma species with the organic molecules arranged either as a blanket film or a nanoscale pattern, and the chemical, morphological and topographic changes induced by these interactions in the macromolecules themselves and the macromolecule defined nanoscale features. In this talk we review recent work aimed at improving our understanding and control of plasma-surface interactions with advanced polymers for nanoscale patterning of materials. Based on collaborations with S. Engelmann, R. L. Bruce, T. Kwon, R. Phaneuf, Y. C. Bae, C. Andes, D. Graves, D. Nest, J. Vegh, E. A. Hudson, B. Long, G. Willson, P. Lazzeri, E. Iacob and M. Anderle. [Preview Abstract] |
Tuesday, October 2, 2007 5:30PM - 5:45PM |
ET1.00006: Comparison of gas-phase chemistry during deposition of amorphous carbon films using capacitive and inductive discharges. S. Ramachandran, L. Overzet, W. Hu, L.S.N. Tao, G.-S. Lee, C. Nelson, M. Goeckner Diamond like carbon films (amorphous carbons) are just beginning to find applications as protective coatings in nano-imprint lithography. These films have appropriate hardness, inertness and surface free energy. They can be deposited using a variety of plasma tools. We compare the capacitive and inductive methane plasmas for depositing films to be used as mold material in nano-imprint lithography. Gas-phase chemistry studies of the deposition process were made using Fourier transform infrared (FTIR) spectroscopy and emission spectroscopy. It was observed that the methane broke down into CH3, CH2, CH and H. In addition, larger species were found in the gas, including acetylene and ethylene. Vibrational and rotational temperatures of several species were determined. Concurrent studies of the resulting films, shows that the capacitive discharge had a larger processing window for the production of suitable quality films. We believe that this is tied to the degree of dissociation of the methane, as well as the presence of the larger species found in the gas phase. [Preview Abstract] |
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