The dynamic behavior of the hydrolysis reaction of Si(OCH3)4 under neutral, basic, and acidic conditions was investigated, for the first time, at the atomic level with short time intervals using a novel tight-binding quantum chemical molecular dynamics program “Colors”. The initial parameters required for the computation were determined completely on the basis of the first principles density functional calculations using Amsterdam density functional program. The simulation results of this study clearly indicate that a flank-side attack mechanism is favored, in all the three cases, for the hydrolysis process, and pentacoordinate silicon intermediates are easy pathways for the displacement of −OCH3 by −OH on silicon. Moreover, the presence of the acid or the base as catalyst promotes the hydrolysis by rapid formation of Si−OH bond in comparison to the hydrolysis under neutral condition. Furthermore, in the case of the latter condition, it was observed that the proton oscillates between −OH and −OCH3 before it migrates to the latter group.

No abstract

We developed a new accelerated quantum chemical molecular dynamics program called "Colors" which can simulate the chemical-mechanical polishing (CMP) processes. It is more than 5,000 times faster than the regular first-principles molecular dynamics program, since it is based on our original tight-binding theory. We employed a SiO 2 particle as a polishing material. Two types of silicon surfaces, clean Si(100) and H-terminated Si(100) 2 × 1, were modeled to clarify the effect of the Si surface structure on the dynamic behaviors of the CMP processes. We paid attention to the bond population of the silicon atom during the CMP processes. The bond population of the silicon atom was decreased by the CMP process on both surfaces, indicating that the electronic state of the silicon wafer became unstable due to the CMP process. It is an interesting finding that the hydrogen atoms were desorbed from the H-terminated Si(100) 2 × 1 surface. The results indicate that our new program can simulate both the chemical reactions and mechanical polishing processes. To the best of our knowledge, this is the first simulator of the CMP processes on the atomic and electronic levels.

No abstract