Development of a molecular dynamics potential for Si-H systems and its application to CVD reaction processes

In order to investigate the reaction probability of silane dissociative adsorption, we developed a new Si-H potential which reproduces the energy and vibration wave number of silicon hydride clusters as well as the activation energy of silane dissociative adsorption at the level of ab-inito calculation. By using molecular dynamics involving our potential, the dependence of reaction probability on molecular and substrate temperatures was investigated and was compared with the experimental results of the translationally activated process. It was found that the reaction probability is significantly more dependent on the internal energy of the silane than on the substrate temperature, and that the process is of a non-Arrhenius type. The reaction probability increases linearly with an increase in translation energy. The dependence on the substrate temperature qualitatively agreed with the experimental results. However, our calculations showed a linear dependence on translation energy, while the experiment showed an exponential function. This difference is attributed to the differences in the shape of the potential energy surface. Tight-binding molecular dynamics were performed for verification. The results predict an early barrier type of potential surface, which contrasts with the late barrier type predicted by our Si-H potential. Comparison with a statistical RRKM model shows that such a difference in the potential energy surface greatly affects the reaction probability's dependence on translation energy. (C) 2004 Elsevier B.V. All rights reserved.