Adhesion promotion method for CVD copper metallization in IC applications

A method is provided for promoting adhesion of CVD copper to diffusion barrier material in integrated circuit manufacturing. The method uses a two-step CVD copper metallization process. Following deposition of a diffusion barrier layer on the IC substrate, a first layer of CVD copper is deposited on the barrier material. The first layer is preferably thin (less than 300 Å) and deposited using a precursor which yields an adherent conforming layer of copper. The suggested precursor for use in depositing the first layer of CVD copper is (hfac)Cu(1,5-Dimethylcyclooctadiene). The first layer of CVD copper serves as a "seed" layer to which a subsequently-deposited "fill" or "bulk" layer of CVD copper will readily adhere. The second copper deposition step of the two-step process is the deposit of a second layer of copper by means of CVD using another precursor, different from (hfac)Cu(1,5-Dimethylcyclooctadiene). The precursor selected for depositing the second layer of CVD copper is preferably one which has a substantially higher deposition rate, or is otherwise less costly or simpler to use, which will lower production costs since most of the mass of deposited copper is in the second layer. Because the second CVD copper layer is deposited on copper, adhesion to the first-deposited layer will be good because the layers are joined by copper-to-copper bonds. Thus, the two layer process provides optimal economy with good adhesion to barrier material.