Deposition of WNxCy thin films by ALCVD™ method for diffusion barriers in metallization

A new process of depositing ternary tungsten nitride carbide WN_xC_y films as a diffusion barrier material for copper metallization has been developed with the atomic layer chemical vapor deposition (ALCVD™) technology. The growth temperature was varied from 300 to 350°C, and the resistivity was in a range of 300-400 μΩcm for a ∼25 nm film. The film composition was influenced by deposition conditions with a W, N and C content of approximately 55, 15, and 30 at.%, respectively. Impurities such as F, O, and B in the bulk of the film were low, less than 1 at.% or under the detection limit of analysis tools used. The deposited films showed excellent compatibility with different substrates including Cu, SiO₂, SiC, Si_xN_y, SiLK and Aurora. Preliminary electrical tests of WN_xC_y on the dual damascene wafers showed promising results.