SOLID-PHASE REACTIONS AND CRYSTALLOGRAPHIC STRUCTURES IN ZR/SI SYSTEMS

Solid-phase reactions and crystallographic structures in the interfacial region of Zr/(100)Si systems, which is closely related to the specific contact resistivity, have been investigated by x-ray diffraction, Auger electron spectroscopy and cross-sectional high-resolution transmission electron microscopy. As-grown Zr films are in an amorphous phase including crystallites. The Zr film on silicon annealed at a temperature of 420-degrees-C for 30 min has a bilayer structure. The upper layer is a crystalline alpha-Zr layer with a (0001) fibrous structure and the lower layer is an amorphous zirconium silicide layer. The formation of the amorphous silicide layer is considered to result from the diffusion of Si atoms from the substrate into the Zr film and to play a major role in a low contact resistivity of 4 x 10(-8) OMEGA cm2 achieved in this system. By annealing above 560-degrees-C, which brings about an increase in contact resistivity, the crystalline Zr layer with the fibrous structure is changed to an amorphous silicide throughout the film and, subsequently, ZrSi2 regions with a (010) preferred orientation is formed at the interface between the amorphous interlayer and the single-crystal Si.