The The Sicl <sub> 4 </ Sub> The / H <sub> 2 </ Sub> Epitaxial Growth Of Single Crystal Silicon Reaction Mechanism Theoretical Research

In this paper, the mechanisms of the reaction which take SiCl₃/H₂ as silicon source gases were investigated theoretically for the first time with Gaussian98 program at B3LYP/6-311G* level. The geometries of all reactants, transition states and productions have been optimized. The active energy of each reaction channel was calculated. Analysis the imaginary vibration mode of all transition states in order to test the transition states. IRC (intrinsic reaction coordinate) was made for confirming the existence of the transition states, further.The paths of the reaction in the gas phase was calculated, the results show that SiCU react with H2 to form SiHCl3 and HC1, SiHCl3 can direct decomposition into SiCl2 and HC1, and SiH4 can be get finally when SiCl2 further react with H2. We investigated the reaction that occurs in the gas phase, and found that the silicon can not been formed in the gas phase. The Si2, Si4 and Si9H12 clusters were chosen for simulating the silicon substrate. The mechanism of the reaction on the substrate surface was calculated, and it is found that the silicon that was not been formed in the gas phase can formed on the silicon substrate surface, and so the silicon crystal can grow on the silicon substrate surface. The active energy of the reaction between the adsorption of SiCl4 on silicon and H2 is lower than that of SiCU direct react with H2 in gas phase, so it can be concluded that the silicon substrate has the catalysis in the reaction process. The rate constant was calculated by TST over a wide temperature range of 900-1600K. Seen from the results, the determinable rate step of reaction in gas phase is the first and the second step. The reaction of the decomposition of SiCU on silicon substrate is finished quickly, While the reaction of adsorption with H2 later is slower, so it is confirmed the determinable rate step of reaction.In this paper, we gave some explanation for the experiment of the monocrystalline silicon vapor-phase epitaxial growth and the microcosmic mechanism of the reactions theoretically. It will provide the dynamical information for the experimental workers to design the experimental techniques and improve the work efficiency.