Solid state amorphization in metal/Si systems

• Published in: Materials science & engineering. R, Reports : a review journal Vol. 29; no. 5; pp. 115 - 152
• Main Author: Chen, L.J
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.09.2000; Elsevier Science
• Subjects: Amorphous interlayers; Applied sciences; Condensed matter: structure, mechanical and thermal properties; Diffusion; interface formation; Exact sciences and technology; Growth law; Metal silicide; Metals. Metallurgy; Physics; Rare-earth metal/Si; Refractory metal/Si; Solid surfaces and solid-solid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Growth law; Amorphous interlayers; Rare-earth metal/Si; Refractory metal/Si; Metal silicide; Interfacial layer; Refractory metals; Heat of mixing; Silicides; Amorphization; Roughness; Amorphous state; Solid-solid interfaces; Experimental study; Diffusion pair; Heat treatments; High-resolution methods; Defects; AES; Tensile stress; Rare earths; Transition elements; Growth mechanism; Silicon; Kinetics; Diffusion; Activation energy; TEM
• ISSN: 0927-796X; 1879-212X
• DOI: 10.1016/S0927-796X(00)00023-1

The formation of amorphous interlayer (a-interlayer) by solid-state diffusion in diffusion couples has been one of the most challenging problems in condensed matter physics in recent years. The a-interlayer has been found to occur in all refractory metal/Si and a number of rare-earth (RE) metal and platinum group metal and crystalline silicon systems. A systematic survey and review of extensive studies on the subject in the past years showed that (1) a negative heat of mixing provides the driving force for the reaction and fast diffusion of one component in the other preempts the formation of crystalline compounds, (2) the growth follows a linear law at the initial stage with activation energy around 1–1.5 eV for refractory metal/Si systems and 0.5 eV for RE metal/Si systems, (3) the dominant diffusing species is Si, (4) the stability of amorphous interlayer depends on the composition, (5) simultaneous presence of multiphases in the initial stage of metal/Si interaction, and (6) good correlations between physical parameters and kinetic data. From the investigation of amorphous interlayers, mechanisms of roughing of epitaxial RE silicide/(0 0 1)Si interface, formation of stacking faults and pinholes in RE silicides have gained in basic understanding. The insight led to successful growth of pinhole-free epitaxial RE silicide layer on (1 1 1)Si. Furthermore, the enhanced formation of technologically important C54-TiSi 2 by high temperature sputtering, a thin interposing Mo layer and tensile stress can all be explained involving some aspects of the amorphous interlayers.