AVS 49th International Symposium
    Electronic Materials and Devices Wednesday Sessions
       Session EL+SS+SC-WeA

Paper EL+SS+SC-WeA9
Stress-induced Dissociative Chemisorption of Oxygen on Si(001)

Wednesday, November 6, 2002, 4:40 pm, Room C-107

Session: Semiconductor Film Growth and Oxidation
Presenter: M. Yata, National Institute for Materials Science, Japan
Authors: M. Yata, National Institute for Materials Science, Japan
Y. Uesugi-Saitow, National Institute for Materials Science, Japan
Correspondent: Click to Email
We have investigated the role of surface stress in dissociative adsorption process of O@sub 2@ on Si(001)-2x1by supersonic molecular beam technique. The tensile stress was externally applied on the surface along[110] direction. The Si(001)-2x1surface reconstructs by dimerization of atoms in adjacent rows. In areas of the surface separated by an odd number of monoatomic steps the orientation of the dimer bonds is rotated by 90° giving 2x1 and 1x2 orientational domains. Their domain populations are changed to relax the stress at the surface and the kinetics of the change depend on the surface temperature.@footnote 1@ Below room temperature, the domain populations were almost equal during the molecular beam experiments. Two co-existing dissociation channels are seen, a trapping-dissociation channel at low translational energy of incident O@sub 2@ and a direct activated channel at high translational energy.@footnote 2@ In case of the trapping-dissociation, O@sub 2@ molecule is trapped to a precursor state and undergoes a kinetic competition between desorption and dissociation. We have estimated a difference in activation barrier heights between desorption and dissociation at 30 meV. The initial dissociative sticking probability for low translational energy of incidence increases as the tensile stress increases. This indicates that trapping-mediated dissociation is enhanced by the stress. We have found that the difference in the activation barrier heights between desorption and dissociation decreases as the stress increases. We will discuss the change of dissociation dynamics with the tensile stress in detail. @FootnoteText@ @footnote 1@ F. K. Men, W.E. Packard and M. B. Webb, Phys. Rev. Lett. 61(1988) 2469.@footnote 2@ B. A. Ferguson, C. T. Reeves and C. B. Mullins, J. Chem. Phys.110(1999)11574.