A method of forming a noble metal cap on a conductive material embedded in a dielectric material in an interconnect structure. The method includes the step of contacting (i) a conductive material having a bare upper surface partially embedded in a dielectric material and (ii) vapor of a noble metal containing compound, in the presence of carbon monoxide and a carrier gas. The contacting step is carried out at a temperature, pressure and for a length of time sufficient to produce a noble metal cap disposed directly on the upper surface of the conductive material without substantially extending into upper surface of the dielectric material or leaving a noble metal residue onto the dielectric material.