The growth of cobalt silicides layer has been studied in Co/Ta, Co/Ta0.5W0.5 and Co/W bilayers grown on Si(100) substrate. The Co and Ta-W films were deposited using thermal evaporation and sputtering techniques, respectively All these samples were annealed at a temperature range from 400 to 1000 degreesC in an N-2 (80%) + H-2 (20%) environment for 60 min. The phase identification and electrical property of the annealed samples were determined by XRD and R-S methods. In the Co/Ta/Si(100) system, we have obtained nearly a single crystalline CoSi2(200) layer with R-S value of approximately 0.9 Omega/square at 900 degreesC. However, reappearance of Co2Ta phase at 1000 degreesC exhibits unsatisfactory thermal stability for this system. It was shown that for the Co/Ta0.5W0.5/Si(100) system, there is a reasonable thermal stability, but CoSi2 layer was grown in a polycrystalline form with R-S value of approximately 2.7 Omega/square at 1000 degreesC. For the Co/W/Si(100) system, we have observed nearly a single crystalline CoSi2(200) layer with a R-S value of approximately 1.0 Omega/square at 900 degreesC exhibiting a good thermal stability in a temperature range from 900 to 1000 degreesC. (C) 2003 Elsevier Science B.V. All rights reserved.