AVS 52nd International Symposium
    Surface Science Friday Sessions
       Session SS1-FrM

Paper SS1-FrM7
Etching of Carbonaceous Thin Films by Atomic Oxygen: The Influence of Chemical Composition, Substrate Temperature and Gas Phase Environment

Friday, November 4, 2005, 10:20 am, Room 202

Session: Surface Modification through Etching
Presenter: H. Fairbrother, Johns Hopkins University
Authors: H. Fairbrother, Johns Hopkins University
J. Gorham, Johns Hopkins University
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The etching of carbonaceous thin films by atomic oxygen (AO) is an important component of many industrial plasma cleaning and decontamination strategies. AO is also the central species responsible for the degradation of polymers exposed to Low Earth Orbit (LEO). To improve the mechanistic understanding of AO mediated erosion processes, the surface reactions of AO with various carbonaceous thin films have been studied using X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM). In situ XPS analysis revealed that AO mediated erosion rates with carbonaceous films increase rapidly as a function of substrate temperature. This effect was correlated in part with the thermal stability of the oxidized carbon species produced as intermediates during the etching process. In low pressure plasma cleaning processes surfaces are typically exposed to a variety of reactive species. As an initial step towards identifying the existence and magnitude of co-operative effects between AO and other reactive species contained in plasma discharges results will also be presented on the erosion of carbonaceous thin films exposed simultaneously to AO and low energy (< 100eV) electrons. In these studies XPS analysis will be augmented by AFM studies, using HOPG as a model substrate for carbonaceous films. To identify their suitability as protective coatings for spacecraft vehicles exposed to LEO the surface reactions of AO with amorphous carbon phosphide films have also been examined. In these studies phosphorous incorporation was found to retard the rate of AO erosion due to the formation of a passivating surface layer that contains highly oxidized phosphorous species.