The formation and growth of CoSi2 inside 0.2-2 mu m linear oxide openings and contact holes prepared by electron-beam lithography have been investigated. A thin, uniform epitaxial CoSi2 was grown inside 0.5 mu m or smaller linear openings and 0.7 mu m of smaller contact holes by both one- and two-step rapid thermal annealing processes. On the other hand, epitaxial and polycrystalline CoSi2 were found to form on silicon near the edge and central region, respectively, inside 0.6 mu m or larger linear openings. The size effect of the oxide openings is correlated to the distribution of local stress induced at the oxide edge. The formation of CoSi at low temperature appeared to be retarded by the local compressive stress near the edge of the linear oxide openings. The relative ease in the epitaxial growth of CoSi2 near the oxide edge of the linear openings and of 0.7 mu m and smaller contact holes is attributed to the thinness of the CoSi layer.