Study of Evaluation of Silicide/Silicon Interfaces by Tunneling Spectroscopy and Effects of H-Termination

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The purpose of this study is to clarify the determining factors of Schottky barrier heights connected with the characteristics of metal/semiconductor contacts, to understand the correlation between contact resistivities and Schottky barrier heights and also, to develop a method in order to control Schottky barrier heights. The formation processes and the electrical properties of epitaxially-grown CoSi_2 films on Si(001) substrates have been investigated and, moreover, the H-termination of Si(001) surfaces to control the interfacial reaction and the introduction of Sil-xGex/Si(100) heterostructures to control Schottky barrier heights have been examined. The main results obtained by this study are as follows :1. AtCo/Si(100) interfaces, CoSi is formed by the diffusion of Co atoms into Si substrates at low annealing temperature and CoSi_2 by the diffusion of Si atoms into silicide films at high annealing temperature. It has been found that the CoSi_2 formation is affected by the doping im … More purities and concentrations in substrates. Moreover, the growth conditions to form pinhole-free and atomically-flat CoSi_2 films have been clarified. The relation between the electrical properties such as Schottky barrier heights and contact resistivities and the local crystallographic structures has been also discussed.2. The stability of H-terminated Si(100) surfaces has been studied, and the local electronic structures of surface Si-H bonds have been examined by scanning tunneling microscopy and scanning tunneling spectroscopy (STM/STS). The reduction of interfacial defects and the improvement of electrical characteristics have been realized by H-termination treatments. It can be concluded that the H-termination treatment is very useful to form an ideal metal/Si interface.3. The interfacial solid-phase reactions and the electrical properties of Ti/Si_<0.8>Ge_<0.2>/Si(100) contacts have been investigated. The Schottky barrier heights of both n-and p-type Si_<0.8>Ge_<0.2>/Si(100) substrates are lowered by annealing above 460ﾟC.It has been concluded that the introduction of SiGe films to the metal/Si interface is very effective to form a very low resistivity contact from a viewpoint of the control of Schottky barrier heights and interfacial reactions. Less