The present invention provides methods for forming cobalt silicide layers, including introducing a vaporized cobalt precursor onto a silicon substrate to form a cobalt layer. The vaporized cobalt precursor has the formula Co2(CO)6(R1—C≡C—R2), wherein R1 is H or CH3, and R2 is H, t-butyl, methyl or ethyl. The silicon substrate is thermally treated so that silicon is reacted with cobalt to form a cobalt silicide layer. Methods for manufacturing semiconductor devices including the cobalt silicide layers described herein and such devices are also provided.