Study of angular influence of C3H5+ ion deposition on polystyrene surfaces using molecular dynamics simulations

The influence of incident angle on the interaction of polyatomic hydrocarbon ions (C3H5+) with polystyrene surfaces is examined using classical molecular dynamics simulations. The forces are determined using the reactive empirical bond order method developed by Tersoff and parametrized by Brenner. The total incident energy is 50 eV and the angles considered are 0degrees (normal to the surface), 15degrees, 45degrees, and 75degrees. At each angle, the outcomes of 80 trajectories are compiled and averaged. The results show that intact ions scatter from the surface in only 2% of the trajectories and that the ions dissociate in 61% of the trajectories at normal incidence. At 75degrees, intact ions scatter away in 56% and they dissociate in only 30% of the trajectories. The largest total amount of carbon is deposited at normal incident angles. However, more ions or ion fragments are predicted to remain near the surface (penetrate 3.5-5.5 Angstrom) at 45degrees. This is because ion fragments tend to penetrate more deeply (6-7 Angstrom) into the surface at smaller angles. Consequently, some inclined angles are found to be most efficient for the deposition of the precursors necessary for polymer thin-film growth. (C) 2002 American Vacuum Society.