IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Tuesday Sessions
       Session SC-TuA

Paper SC-TuA10
STM-Controlled Epitaxy of Cobalt-Semiconductor Compounds

Tuesday, October 30, 2001, 5:00 pm, Room 124

Session: Semiconductor Heterojunctions
Presenter: I. Goldfarb, Tel Aviv University, Israel
Authors: I. Goldfarb, Tel Aviv University, Israel
G.A.D. Briggs, Oxford University, UK
Correspondent: Click to Email
Metal-semiconductor compounds play a key role in micro- and optoelectronic devices, mostly as contacts and interconnects. At present, the most popular are the silicides of Ti, and even more so of Co (due to its suitability for self aligned process). However both CoSi@sub 2@ and TiSi@sub 2@ are usually used in a form of polycrystalline thin films. While monocrystalline epitaxial growth of TiSi@sub 2@ on silicon is impeded by its large lattice mismatch between them, it could have been expected for the CoSi@sub 2@ in view of the latter's low mismatch with silicon. Obviously, monocrystalline contacts with improved electrical characteristics are highly desirable. Yet, CoSi@sub 2@ does not grow on silicon as a moncrystalline two-dimensional layer, at least not on the Si(001) surface, where CoSi@sub 2@ forms misoriented three-dimensional islands. CoGe@sub 2@ is another interesting metal-semiconductor compound that can be used, for example, as contacts to SiGe alloys and GaAs. CoGe@sub 2@ forms three-dimensional islands on Ge/Si(001), which are very similar to the CoSi@sub 2@ ones on Si(001). In this work we investigate the mechanisms of CoSi@sub 2@ and CoGe@sub 2@ growth by carefully-controlled e-beam evaporation of Co onto Si(001) substrates, as monitored in situ, from the very initial submonolayer stages, by scanning tunneling microscopy (STM) and reflection high-energy electron diffraction (RHEED). In order to affect the resultant epilayer morphologies, we use flat and vicinal surfaces, and two different ways of synthesis: reactive deposition (where Co is deposited onto hot substrate), and solid-phase reaction (where Co is deposited at lower, or room temperature). We attempt to account for the observed morphological differences of the epilayers by correlating them with the above-mentioned parametric differences.