SiHCl_3-H_2气相外延生长Si单晶反应机理的理论研究

Theoretical Study of Reaction Mechanism of Silicon Single Crystal Epitaxial Growth in SiHCl_3-H_2 Gas Phase

采用密度泛函理论计算方法,在B3LYP/6-311G*水平下,计算并得到了SiHCl3与H2反应各反应通道上各驻点的构型、振动频率和能量.结果表明,在气相中SiHCl3分解的通道d和SiHCl3与H2反应的通道c为竞争反应,但其均未还原出Si原子,只有衬底Si参与SiHCl3-H2的反应,Si原子才淀积在Si衬底上.

According to the experimental condition, we projected three possible paths a, b, c of the reaction between SiHCl3 and H2 and path d of SiHCl3 decomposition in gas phase. The substrate silicon-participating reactions that include SiHCl3-H2-Si, SiHCl3-H2-Si2, SiHCl3-H2-Si9H12 were also discussed and the substrate silicon is simulated by using clusters of Si, Si2, Si9H12 respectively. The geometries, vibrational frequencies and energies of every stable point of the system were calculated by using Gaussian 98 program at B3LYP/ 6-311 G^＋ level. It is shown that the decomposition paths d and c of the reaction between SiHCl3 and H2 can be considered as the competing reaction in gas phase, but silicon atoms were not formed. So we consider that single crystalline silicon can deposit on the substrate silicon only under the condition of reaction between SiHCl3-H2 and the substrate silicon.