Mechanism of chemical erosion of sputter-deposited C:H films

Abstract
The mechanism of thermally activated chemical erosion of sputter-deposited C:H films of a few atomic layer thickness is investigated using thermal desorption spectroscopy. Methane, CH3 radicals, and various C2Hj species of molecular and radical nature desorb as gaseous products above 600 K competitively to H2. C-CiHj bond breaking is determined to be the rate limiting step of hydrocarbon production. The reaction is of first order with respect to CiHj precursors in the films with a distribution of activation energies, 56±5 kcal/mol for methane production. CH3 radical desorption occurs predominantly from the very surface of the C:H films.