EPITAXIAL-GROWTH IN CU/SI(001)2X1 AT HIGH-TEMPERATURES

The growth mechanism of Cu/Si(001)2 x 1 has been studied by means of scanning RHEED (reflection high energy electron diffraction) microscopy and scanning Auger electron spectroscopy. We obtained the following experimental results: (1) At room temperature, an intermixing layer of Cu with the Si surface is formed and no defined interface structure is observed. (2) At high temperatures (T approximately 500-degrees-C), anisotropic growth of islands is observed on Si(001)2 x 1 and the long axis of the islands corresponds to the direction normal to the dimmer row. The distribution of the anisotropic islands is closely correlated with the domain structure of 2 x 1 and 1 x 2. (3) The islands are composed of Cu-silicide and the interface regions between the islands and the substrate are rich in Si. (4) The small reduction of the Si Auger signal with increasing Cu coverage (0-100 ML) upon deposition at 500-degrees-C is explained by three-dimensional nucleation of islands with a low density of on the Si clean surface 1 x 1 structure. Island formation occurs in a modified mode of Volmer-Weber growth. Lastly, the nucleation mechanism of the Cu-silicide islands is discussed.