The growth of CoSi2 between Co/Zr bilayers on amorphous and on crystalline silicon substrates was investigated. The Zr and Co films were deposited with an electron-beam evaporation system, followed by rapid thermal annealing using temperatures between 500 and 800 degrees C with 100 degrees C increments. The phase identification was carried out by XRD, and chemical compositions of these elements were analyzed by AES. The surface and interface morphologies of Co/Zr bilayer films were investigated by cross-sectional TEM. CoSi2 was formed epitaxially on the crystalline Si substrate while polycrystalline CoSi2 was grown on the amorphous Si substrate. The formation temperature of Co-silicide on the amorphous Si substrate was lower than that on the crystalline Si. The interface of the CoSi2 layer formed on the amorphous Si substrate exhibits better uniformity than the CoSi2 formed on the crystalline substrate. The sheet resistance of CoSi2 on crystalline Si was lower than that on amorphous Si at high temperatures (700, 800 degrees C) while the latter exhibited lower sheet resistance at low temperatures.