A method for depositing metal layers on semiconductor substrates by a thermal chemical vapor deposition (TCVD) process includes introducing a process gas containing a metal carbonyl precursor in a process chamber and depositing a metal layer on a substrate. The TCVD process utilizes a short residence time for the gaseous species in the processing zone above the substrate to form a low-resistivity metal layer. In one embodiment of the invention, the metal carbonyl precursor can be selected from at least one of W(CO)6, Ni(CO)4, Mo(CO)6, Co2(CO)8, Rh4(CO)12, Re2(CO)10, Cr(CO)6, and Ru3(CO)12 precursors. In another embodiment of the invention, a method is provided for depositing low-resistivity W layers at substrate temperatures below about 500° C., by utilizing a residence time less than about 120 msec.