AVS 53rd International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS2-TuM

Invited Paper PS2-TuM1
New Methods for Studying Plasma-Surface Interactions

Tuesday, November 14, 2006, 8:00 am, Room 2011

Session: Plasma Surface Interactions I: Joint AVS-AIChE Session
Presenter: V.M. Donnelly, University of Houston
Authors: V.M. Donnelly, University of Houston
J. Guha, University of Houston
P.F. Kurunczi, University of Houston
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We have developed a new approach for studying plasma-surface interactions. A cylindrical substrate in the reactor wall is rotated at up to 200,000 rpm, allowing the surface to be repeatedly exposed to the plasma (about 40% of the time) and then analyzed in differentially pumped chambers in as little as 150µs after plasma exposure. Delayed 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). Using these methods, we have studied oxygen and chlorine-containing plasma reactions on anodized Al. By varying the substrate rotation frequency, we can determine the overall kinetics of product formation and desorption. We observe desorption of Cl@sub 2@ in chlorine plasmas, O@sub 2@ in oxygen plasmas, and a mixture of Cl@sub 2@, O@sub 2@, ClO, and ClO@sub 2@ products in Cl@sub 2@/O@sub 2@ plasmas, due to recombination reactions on the surface. Absolute desorption yields are computed from calibrations based on the pressure rise in the differentially pumped MS chamber. We also detect chemisorbed Cl and O by AES in these plasmas, and find little dependence on substrate rotation frequency. From a combination of all these measurements it appears that recombination in pores of the anodized aluminum is responsible for the long decay time of desorbing products, and the relatively high probabilities for recombination. @FootnoteText@ P.F. Kurunczi Present affiliation: Varian Semiconductor Equipment, Gloucester, MA 01930.