The silicide formation by annealing plasma-enhanced atomic layer deposition (PE-ALD) Co and physical vapor deposition (PVD) Co was comparatively studied. Very pure Co films were deposited by PE-ALD with CoCp2 and NH3 plasma. However, various analyses have shown that amorphous SiNx interlayer was formed between PE-ALD Co and Si due to the NH3 plasma exposure in contrast with PVD Co. Due to the nitride interlayer, CoSi2 was epitaxially grown from PE-ALD Co by rapid thermal annealing through nitride mediated epitaxy. This process scheme is expected to provide a simple route for contact formation in future nanoscale devices.