Complex dynamics during the reactive scattering of Si+ (2P) and H2

Reactions of silicon hydrides have recently attracted considerable attention due to their importance in plasma enhanced chemical vapor deposition (PECVD) of silicon for the microelectronics industry. Trajectories of reactive and non-reactive collisions between Si+ and H2 are simulated over a range of collision energies from 0.5 to 9 eV using the semiempirical molecular orbital method PM3, and our results lead to a much deeper understanding of one of the most fundamental reactions for deposition techniques. Vibrational, rotational and translational excitation of the SiH+ product are reported as a function of impact kinetic energy. At impact energies below 4 eV, the system passes through configurations in which all three atoms interact strongly for times that can be several orders of magnitude longer than one rotational period. At higher translational energies, the product distributions are consistent with a direct reaction mechanism. All possible energy transfer mechanisms are studied for both low and high impact energies and possible implications for the deposition of silicon are discussed.