[en] Epitaxial formation of CoSi₂ nanolayer by solid state reaction of Co-Si in refractory metal intermediate-layer and cap-layer systems was investigated. Thin films of Ta and W, as the refractory metal intermediate or cap layers of the Co film, were deposited on Si(100) substrate and then heat-treated. The both interlayers resulted in formation of epitaxial CoSi₂ with (100) crystallographic orientation at 900⁰C. However, in the Ta intermediated system, the grown CoSi₂ layer was thermally unstable at 1000 deg. C, unlike the W system with a stable silicide layer. We found that use of W cap-layer cannot yield an epitaxial CoSi₂ phase. But, a Ta cap-layer resulted in formation of epitaxial CoSi₂(100) layer even in a lower temperature (800 deg. C). Again, in the presence of Ta, the grown CoSi₂ layer was thermally unstable at 900 deg. C