Direct identification of the synergism between methyl radicals and atomic hydrogen during growth of amorphous hydrogenated carbon films

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Abstract
The simultaneous interaction of methyl radicals ( CH 3 ) and atomic hydrogen (H) with the surface of amorphous hydrogenated carbon (a-C:H) film is investigated. Two identical quantified beamsources for H and CH 3 are used. The growth and/or erosion during the simultaneous interaction of the two beams with an amorphous hydrogenated carbonfilm is monitored by using in situ real-time ellipsometry at a substrate temperature of 320 K. Interaction with the CH 3 beam alone causes slow growth, corresponding to a sticking coefficient for CH 3 of ∼3×10 −5 . Simultaneous interaction of the atomic hydrogen beam and the CH 3 radical beam yields a sticking coefficient for CH 3 of 3×10 −3 , which is two orders of magnitude larger than for CH 3 alone. From a microscopic modeling of this synergistic growth, the reaction probability for CH 3 adsorbing at an adsorption site, which is created by atomic hydrogen at the surface, is derived to be 0.14.
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