GROWTH AND CHARACTERIZATION OF EPITAXIAL NI-SILICADE AND CO-SILICIDE

This review presents an overview on the recent progress achieved in the epitaxial growth of Ni and Co silicides on Si(111) by UHV deposition techniques. While focusing on the disilicides NiSi2 and CoSi2, the discussion includes as well some less Si-rich intermediate phases which occur during the solid phase reaction of the metal with Si. They turn out to be especially important in the case of Ni. For both disilicides the merits of using two-step deposition processes are emphasized in which an ultrathin template is formed first by pure metal deposition or by codeposition in order to pin subsequent epitaxial growth. The defect structure and its dependence on the growth parameters are analysed in detail for CoSi2, this being the technologically more important material due to the possibility to form structures buried in Si and even CoSi2/Si superlattices. A substantial part of the review is devoted to the electrical properties of Ni and Co silicides and their relation to the structural parameters. In particular we discuss the Schottky barrier at type-A and type-B NiSi2/Si(111) interfaces as well as interface scattering and magneto-transport in thin CoSi2 films. Finally, one of the most promising applications is described, namely the permeable base transistor with a CoSi2 gate embedded in Si.