Single-crystalline growth of COSi2 by refractory-interlayer-mediated epitaxy

Single-crystal epitaxial quality Of CoSi2 films grown on Si(1 0 0) by refractory-interlayer-mediated epitaxy has been investigated. Thin layers of 10 nm co-sputtered WxTa(1-x), as refractory metal interlayers deposited on the Si, were followed by 25 nm of evaporated Co layer. The fabricated Co/WxTa(1-x)/Si(1 0 0) systems were annealed in a temperature range from 400 to 1000 degreesC in an N-2(80%) + H-2(20%) ambient for 1 h. The annealed samples were analyzed and compared by sheet resistance measurement, X-ray diffraction, scanning electron microscopy, and wavelength dispersive spectroscopy techniques. In Co/ W0.25Ta0.75/Si(1 0 0) system, with the best thermal stability, the grown CoSi2 layer exhibits an optimum single-crystalline quality with a sheet resistance of 1.1 Omega/sq at 1000 degreesC. The achievement of the best silicide in this system is explained on the basis of a nearly instantaneous diffusion of Co through the intermediate layer at high temperatures. (C) 2004 Elsevier B.V. All rights reserved.