Formation of thin CoSi2 nanohexagon arrays buried in single crystalline Si substrates. Effects of the orientation of the external surface of the Si host.

GIOVANETTI, L, J.; DOS SANTOS CLARO, P. C.; REQUEJO, F. G.; MONTORO, L. A.; RAMIREZ, A. J.; ZHANG, L.; CRAIEVICH, A. F.; KELLERMANN, G.

Sydney

Congreso; 15th International Small-Angle Scattering conference (SAS 2012); 2012

The Australian Nuclear Science and Technology Organisation

During the last decades an increasing demand for the development of new methods of preparation of nano-composite materials suited for technological applications has been observed [1]. The interest on these nanomaterials is related to the fact that many of their properties can be varied in a continuous way by changing the size, shape and/or spatial ordering of their basic nanoparticles. Silicides of transition metals such as, for example, CoSi2 are of great interest because of the possibilities that they open to applications as a contact material for microelectronic devices [2]. In order to develop new devices with promising technological perspectives, the challenge is now to produce these nanomaterials with the desired properties in large scale integration. This requires preparation methods able to control the size, shape and spatial order of the nanoparticles over relatively large areas as compared with the size of nanoparticles themselves. A simple method for obtaining buried arrays of CoSi2 plates coherently embedded in a Si host lattice was described in a previous study [3]. In this previous investigation it was demonstrated that thermally activated diffusion of Co atoms embedded in a SiO2 thin film deposited on the (001) flat surface of a Si wafer promotes the formation of CoSi2 nanoplates inside the Si single crystal. The experimental results indicated that the nanoplates exhibit a hexagonal lateral shape and a remarkable uniform thickness. The lattice of each CoSi2 nanoplates was shown to be coherent with the host Si lattice, and each of them is parallel to one of the four planes belonging to the Si{111} crystallographic family of planes. In order to obtain additional information about the effects of the diffusion of Co atoms inside Si single crystals, the same preparation procedure previously used for deposition of SiO2 thin films on Si(001) was applied to three Si wafers with different orientations of their external surface, namely Si(001), Si(011) and Si(111). In order to investigate the features of the nanostructure promoted by deposition of Co containing SiO2 thin films on these different Si surfaces, all samples were subjected to equivalent thermal treatment and then characterized by transmission electron microscopy (TEM) and grazing-incidence small-angle X-ray scattering (GISAXS).