Growth and characterization of epitaxial Ni and Co silicides

Abstract

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 $\text{CoSi}{}_2\text{Si}$ 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 $\text{NiSi}{}_2\text{Si(111)}$ 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.