Bulletin of the American Physical Society
2006 59th Annual Gaseous Electronics Conference
Tuesday–Friday, October 10–13, 2006; Columbus, Ohio
Session VF1: Plasma-Surface Interactions |
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Chair: Svetlana Radovanov, Varian Semiconductor Equipment Room: Holiday Inn Salon CD |
Friday, October 13, 2006 8:00AM - 8:30AM |
VF1.00001: Plasma-Surface Interactions on a Spinning Wall Probed by Mass Spectrometry and Auger Electron Spectroscopy Invited Speaker: We have developed a new approach for studying plasma-surface interactions. A cylindrical substrate in the reactor wall is rotated at a variable frequency of 800 to 200,000 rpm, allowing the surface to be exposed to the plasma 40{\%} of the time and then analyzed in differentially pumped chambers at variable times after plasma exposure. Desorption of products from the surface is detected by a chopped molecular beam mass spectrometer (MS), while adsorbates are observed by Auger electron spectroscopy (AES). We have studied oxygen and chlorine-containing plasma reactions on anodized Al. We observe desorption of Cl$_{2}$ in chlorine plasmas, O$_{2}$ in oxygen plasmas, and Cl$_{2}$, O$_{2}$, ClO, and ClO$_{2}$ products in Cl$_{2}$/O$_{2}$ plasmas, due to recombination reactions on the surface. Absolute desorption yields are computed from a calibration of the pressure rise in the differentially pumped MS or AES chamber. Chemisorbed Cl and O detected by AES have little if any dependence on substrate rotation frequency. From these combined results, it appears that most adsorbates are strongly bound and do not participate in recombination and desorption. Recombination of a small percentage of weakly bound species occurs with a range of rates on the rough and porous anodized Al surface. In collaboration with Joydeep Guha, University of Houston. [Preview Abstract] |
Friday, October 13, 2006 8:30AM - 8:45AM |
VF1.00002: Influence of Ion Flux, Ion Energy, Fluorine Availability, and Surface Temperatures on SiO$_{2}$ Etch Rates in FC Plasmas Caleb Nelson, Sanket Sant, Lawrence Overzet, Matthew Goeckner A long residence time (4.9 s) plasma was employed to examine plasma surface interactions. Gas and surface reactions were correlated for different F:C ratio feedgas. \textit{In situ} measurements of CF$_{x}$ densities and process rates were made using an FTIR multipass system and an ellipsometer, respectively. Absolute fluorine densities were measured using actinometry. It was observed that etch and deposition rates varied as a function of ion flux, ion energy, fluorine availability, and surface temperature. These parameters were varied by changing source to chuck gap, increasing chuck bias power, different feedgas, and plasma induced surface temperature changes, respectively. Etch rates were found to increase with ion flux in a limited regime. Increasing ion energy was correlated to an increase in the overall etch rate. At low bias powers, a fluorine rich environment (CF$_{4})$ produced high etch rates, while a fluorine deficient plasma (C$_{4}$F$_{8})$ transitioned to lower etch rates and deposition. Finally, increasing surface temperature was found to change the net surface mechanism from etch to deposition. [Preview Abstract] |
Friday, October 13, 2006 8:45AM - 9:00AM |
VF1.00003: In-situ measurement of an accumulation and a reduction of bottom charging on a SiO$_{2}$ contact hole with a high aspect ratio in a pulsed 2f-CCP in Ar and in CF$_{4}$/Ar Takeshi Ohmori, Takeshi K. Goto, Takeshi Kitajima, Toshiaki Makabe, Seiji Samukawa, Ikuo Kurachi It will be essential to develop in-situ diagnostics for charging damage of a surface exposed to plasma etching under close and complementary cooperation between optical and electric procedures in a top-down nanoscale plasma etching. The charging damage to the lower level elements in semiconductor devices is a latent issue during plasma etching of a topologically patterned wafer. In our previous paper, we have experimentally demonstrated a reduction of charging potential on a SiO$_{2}$ contact hole at the aspect ratio of 5, by utilizing the acceleration of negative charges to a wafer in a pulsed 2f-CCP with a SPC operation of the bias voltage in CF$_{4}$/Ar, and temporal change of the charging potential was observed corresponding to the flux velocity distribution of positive and negative charges incident on the contact hole under the conditions of a reduction on the charging potential [1]. In this work, we focus on the bottom charging potential at the high aspect ratio of 10 in a 2f-CCP in Ar and CF$_{4}$/Ar. The charging potential is increased above 55 V at a self-bias of -220 V in Ar. The potential in CF$_{4}$/Ar is decreased as compared with that of Ar. \newline [1] Appl. Phys. Lett. \textbf{83} (22), 4637-4639 (2003), Jpn. J. Appl. Phys. Express Lett. \textbf{44} (35), 1105-1108 (2005). [Preview Abstract] |
Friday, October 13, 2006 9:00AM - 9:15AM |
VF1.00004: Production of hyperthermal neutrals on surfaces Tatiana Babkina, Timo Gans, Uwe Czarnetzki, D.A. Kovacs, Detlef Diesing The production of hyperthermal neutrals through neutralisation of energetic ions impinging an electrode surface is investigated. Measurements and computer simulations are carried out for various species (H, D, He, Ar) on different surfaces (C, Al, Fe, Au, W) for energies up to a few hundred eV. All measured energy distribution functions of hyperthermal neutrals are in very good agreement with the simulation results. The fraction of reflected hyperthermal neutrals and the shape of their energy distribution function depend strongly on the mass ratio of the impinging ion and the surface material. A smaller ratio results is: more reflected particles, a higher mean energy, and a smaller energy spread. The produced hyperthermal neutrals can be used as a tuneable beam source with controlled energy distributions. Kinetically induced electron emission from metal surfaces is investigated for hyperthermal hydrogen and deuterium projectiles. The obtained results are in agreement with computer simulations and are well described by a model for the energy dissipation into the electronic system of the metal. [Preview Abstract] |
Friday, October 13, 2006 9:15AM - 9:30AM |
VF1.00005: Molecule formation in plasma at surface D.C. Schram, J.H. van Helden, R.A.B. Zijlmans, G. Yagci, J. Ropcke, S. Welzel, O. Gabriel, R. Engeln With diode laser spectroscopy and mass spectrometry the generation of new molecules is studied in two types of plasmas: an expanding thermal plasma at TU/e and a microwave discharge at INP. Molecules formed in argon plasmas with N, H, O and C containing molecules were measured in a two laboratory study. Flows, pressure and power were designed such that an appreciable portion of the admitted gases could be dissociated. The results are very similar: predominantly H$_{2}$, N$_{2}$, CO, H$_{2}$O and/or O$_{2}$ are formed and to a lesser extent, NO, HCN and NH$_{3}$, C$_{n}$H$_{m}$ and CO$_{2}$. Also H$_{2}$CO is observed. Surface generation is concluded for most of the observed molecules. The surface is passivated with radicals from the plasma and the abundances of specific precursor adsorbants as H, N, OH, NH$_{2}$, NO, CH$_{3}$ etc. is apparently important for the production of new molecules. Observation of excited species as H$_{2}$(r,v), N$_{2}$* and NO$_{2}$ (shuttle glow) near to surfaces at high fluxes of radicals forms a further support for the surface production mechanism. [Preview Abstract] |
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