AVS 46th International Symposium
    Plasma Science and Technology Division Thursday Sessions
       Session PS-ThM

Paper PS-ThM2
Hydrogen Atom Reactions in a-SiC:H Film Growth

Thursday, October 28, 1999, 8:40 am, Room 609

Session: Plasma-Surface Interactions II
Presenter: S.F. Bent, Stanford University
Authors: M.-S. Lee, Stanford University
S.F. Bent, Stanford University
Correspondent: Click to Email
The reactive hydrogen flux in plasma-enhanced chemical vapor deposition has an influential role on film growth both by acting as an excitation source and by altering growth pathways. In this work, the role of hydrogen and the evolution of hydride groups during growth and post-growth treatment of hydrogenated amorphous silicon carbon alloys (a-SiC:H) is investigated. Because the film properties depend on the hydrogen distribution in the films, understanding the hydrogen reaction pathways is important for developing control over the material properties. Thin a-SiC:H films were grown by several methods, including plasma-enhanced chemical vapor deposition (CVD) and hot-wire CVD. Methylsilanes were used as single source precursors in a low pressure regime between 200 and 600 K. In situ vibrational spectroscopy was used to provide a detailed identification of the hydride bonding in the film, and near-edge X-ray absorption fine structure (NEXAFS) provided supporting information on carbon and silicon bonding. Studies were made of the effect of H@sub 2@ dilution and post-growth hydrogenation, using isotopic labelling. These experiments were complemented by temporal studies of deuterium exchange reactions, which were used to monitor and differentiate the elementary reactions between D atoms and SiH@sub x@ and CH@sub x@ groups in the material. Different kinetic rates and temperature dependences were observed for the reaction of D with silicon- vs carbon-hydride groups. For the SiH@sub x@ groups, rapid exchange was followed by a slower insertion mechanism; the less facile CH@sub x@ loss was not followed by a detectable increase in CD@sub x@, suggesting that etching or C=C formation may be more important for carbon. These reactions, and their temperature dependence, have important consequences for the final film structure and properties.