ION-BEAM SYNTHESIS OF SILICON-BASED MATERIALS

Ion beam synthesis (IBS) is a useful technique to fabricate silicon-ba sed materials. We will discuss the different mechanisms of IBS for mat erials forming solid solutions or stoichiometric compounds. An interes ting completely miscible system is Si-Ge because epitaxial Si1-xGex la yers will be used for future microelectronic devices. As an example fo r a stoichiometric compound we have investigated a metallic silicide, CoSi2, which is a favorite material for contacts and interconnects of deep submicron transistors and which is structurally compatible with s ilicon allowing epitaxial layer formation. Furthermore, we show the sy nthesis of a ternary silicide compound Co1-xPdx Si-2. One of the key a dvantages of IBS is the possibility of direct patterning of structures by the use of an implantation mask. We investigated the dimensional l imits of the fabrication of epitaxial CoSi2 nanowires in Si(100). Thes e metallic wires with diameters as small as 170 nm show quantum effect s of the electric transport by the observation of weak localization ef fects. The usefulness for applications of ion beam synthesized buried CoSi2 layers in silicon is demonstrated by the realization of an ultra fast vertical metal/semiconductor/metal photodetector. (C) 1998 Elsevi er Science S.A. All rights reserved.