Interactions of the SiHxCly Silicon Species with the Si4H9 Cluster

The CNDO/Z method was applied to the investigation of the surface reaction occurring during the epitaxial growth of silicon single crystals. The aim of the work was to find silicon species from which the crystal growth is possible under the reaction conditions chosen to comply with the application of the CVD technological method. Calculations suggest that the SiH,, SiHCl and SiH, species are feasible for the further growth. Silicon semiconductor platelets are conventionally manufactured by the CVD (Chemical Vapour Deposition) technique, consisting in the deposition of layers of the solid on the surface of a suitable substrate, the former arising from a heterogeneous chemical reaction of the starting gaseous substances'. During the deposition process, the gaseous substances in the reactor are transported from the inlet to the deposition section, where the starting substance diffuses from the bulk to the substrate surface. During the diffusion, the starting substances can react with hydrogen to give various intermediates. The solid separates on the substrate surface, and the silicon atoms released from the adsorbed species can migrate along the substrate surface until they occupy a site with an energy suitable for embedding into the crystal structure of the substrate. After the deposition, the gaseous reaction products diffuse back into the bulk and are carried in the main stream away to the reactor outlet. The aim of the present work was to simulate the epitaxial growth of a silicon single crystal from the gas phase. Silicon species are adsorbed on the crystal surface, and after the substituents detach, the silicon atoms become part of the crystal. The choice of the species was determined by the most frequently employed deposition media - SiCI4, SiC12H2 or SiH, with a fraction of hydrogen. During the deposition,