IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
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       Session TF-WeM

Paper TF-WeM8
A Theoretical Study of the Chemical Vapor Deposition of (100) Silicon from Silane

Wednesday, October 31, 2001, 10:40 am, Room 123

Session: Fundamentals of Deposition
Presenter: J.K. Kang, Stanford University
Authors: J.K. Kang, Stanford University
C.B. Musgrave, Stanford University
Correspondent: Click to Email
We use quantum chemistry to investigate the chemical vapor deposition of (100) silicon from silane. The CVD reaction proceeds through four sequential steps. The first step is activation of surface sites through H2 desorption from the Si (100)-2x1 monohydride surface. We find that H2 desorption proceeds through a two-step pathway. The barrier for the first step is 35.1 kcal/mol while the second step proceeds with a barrier of 31.1 kcal/mol. Next, dissociative adsorption of SiH4 occurs, where SiH3 and H fragments add to two surface dangling bonds. We find the barrier to adsorption to be 4.3 kcal/mol. Then, adsorbed SiH3 transforms directly to SiH2 through simultaneous H migration from adsorbed SiH3 to the dimer and through a dimer-opening and ring-closing reaction with a barrier of 70.7 kcal/mol. We also find an alternative path where adsorbed SiH3 transforms to SiH2 through two sequential steps in the presence of atomic H. One pathway proceeds through hydrogen abstraction from the adsorbed SiH3 on the surface with a barrier of 0.4 kcal/mol followed by a dimer-opening and ring-closing step with a barrier of 23.3 kcal/mol. An alternative path proceeds through abstraction of H from the dimer and has a barrier of 0.2 kcal/mol followed by dimer-opening and ring-closing steps with a barrier of 32.9 kcal/mol. Finally, a dihydride surface with SiH2(a) formed through dimer-opening and ring-closing reactions transforms to a monohydride surface with SiH(a) through two-sequential steps of H2 desorption from one side of dimer followed by H migration from the other side of the dimer. The predicted barrier for this H2 desorption is 47.1 kcal/mol while that for H migration is 2.8 kcal/mol. In addition, we find that the overall theoretical barrier of 60.6 kcal/mol for H2 desorption is in a good agreement with the experimentall barrier (58.2 +/- 2.3 kcal/mol).