AVS 51st International Symposium
    Surface Science Thursday Sessions
       Session SS3-ThM

Paper SS3-ThM7
Morphological Evolution during Competitive Etching and Oxidation of Vicinal Si(100) Surfaces

Thursday, November 18, 2004, 10:20 am, Room 213B

Session: Halogen and Oxygen Surface Reactions and Etching
Presenter: M.A. Albao, Iowa State University
Authors: M.A. Albao, Iowa State University
D.-J. Liu, Iowa State University
J.W. Evans, Iowa State University
Correspondent: Click to Email
Exposure of a vicinal Si(100) surface to oxygen at ~600C produces etching-mediated step recession. This process is impacted by the formation oxide islands which act as pinning centers for the receding steps, as observed in STM studies by Pelz et al. We develop an atomistic model for this process which accounts for the interplay between oxygen surface chemistry (adsorption, diffusion, oxide formation, and etching via SiO desorption) and the Si surface and step dynamics (anisotropic diffusion and aggregation of vacancies formed by etching with each other or with steps, and attachment-detachment dynamics at steps incorporating anisotropic energetics). Kinetic Monte Carlo simulation of this model produces etch morphologies where receding steps retain qualitative features of their equilibrium morphology (alternating rough SB steps and smooth SA steps), although pinning greatly distorts equilibrium structure (as seen in STM studies). Even without pinning, step evolution is a driven far-from-equilibrium process (as is step flow during MBE) which is impacted by the details of the etching process (e.g., anisotropic vacancy diffusion can lead to an alternation between etch pit nucleation and step flow on adjacent terraces). Simulations used to characterize the dependence of the complex etch morphologies for this model on temperature and oxygen pressure.