Anisotropy in the growth rates of silicon deposited by reduction of silicon tetrachloride

Abstract

The Si epitaxial growth on the {111} facet using the SiCl 4-H 2 process has shown a rapid lateral growth rate with remarkable anisotropy. This phenomenon can be explained in terms of Kossel's model which is modified by taking the surface migration process of adatoms into consideration. In the case of insufficient supply of Si adatoms, the lateral growth rate does not depend on kink density due to the predominant attachment rate of adatoms to kink; the number density of migrating adatoms to kinks is rate-limiting for the lateral growth rate. In the case of sufficient supply of Si adatoms, however, the density of kinks is rate-limiting for the lateral growth rate. The faceted surface morphology reveals that a uniform distribution of pyramidal hills becomes more pronounced at lower temperatures. It is shown that the density of pyramids increases with increasing supply rate of material gas and decreasing temperature, and that the interpyramidal distance is governed by the surface migration length and the minimum density of adatoms for nucleus formation. The lateral growth rate seems to depend on the inter-pyramidal distance. following the diffusion equation for adatoms on the facet.