Fourier transform infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy (XPS), and ab initio density functional theory-based molecular dynamics simulations demonstrate fundamental mechanisms for CH3 abstraction from organosilicate films by thermal O(P3). Ex situ FTIR analysis demonstrates that film exposure to thermal O(P3) yields chemical changes similar to O2 plasma exposure. In situ XPS indicates that exposure to thermal O(P3) yields O/OH incorporation in the organosilicate film concurrent with carbon loss from the surface region. These results are consistent with simulations indicating specific low kinetic barrier (<0.1 eV) reactions resulting in concurrent Si–C bond scission and Si–O bond formation.

Nanocrystals of hexagonal nickel carbide have been synthesized via physical vapor deposition of elemental nickel onto the surface of vertically aligned carbon nanotubes. Combining high-resolution transmission electron microscopy (HRTEM) with three-dimensional atom probe tomography (3DAP) confirmed that these nanocrystals have a hexagonal structure, are enriched in carbon, and have a composition of ∼Ni-25 at. % C (Ni 3 C). This metastable hexagonal nickel carbide phase appears to be stabilized due to the growth of the nanocrystals on the surface of the nanotubes that act as a template and also as a source of carbon. The stability of this nickel carbide phase has also been investigated by density functional theory (DFT) calculations and compared to the experimental results.

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Accurate combined-hyperbolic-inverse-power-representation of ab initio potential energy surface for the hydroperoxyl radical and dynamics study of O + OH reaction J. Chem. Phys. 138, 134117 (2013); 10.1063/1.4795826Reaction mechanisms of oxygen plasma interaction with organosilicate low-k materials containing organic crosslinking groups J. Vac. Sci. Technol. A 30, 061302 (2012); 10.1116/1.4755898 Ab initio simulations of oxygen atom insertion and substitutional doping of carbon nanotubesThe interactions of the oxidizing plasma with the low k dielectric materials and the associated damage mechanisms are of great technological interest for processing current and next generation low k materials. Density functional theory based ab initio molecular dynamics simulations have been performed to evaluate the reaction mechanisms of thermal atomic oxygen ͓in triplet ͑ 3 P͒ or singlet ͑ 1 D͒ state͔ with the organosilicate low k materials represented by model systems. The threshold kinetic energies of attacking atomic oxygen and the reaction pathway were found to be highly incident angle dependent. Carbon abstraction through methyl radical formation can happen at energy barriers as low as 0.1 eV when O radical attack occurs along the axes inclined to the Si-C bond. The simulation results agree well with recent experiments and support diffusion-controlled etching rate dependence, and dielectric constant increases due to oxygen plasma etching.