Compositionally graded titanium nitride film for diffusion barrier applications

摘要

A diffusion barrier film includes a layer of compositionally graded titanium nitride, having a nitrogen-rich portion and a nitrogen-poor portion. The nitrogen-rich portion has a composition of at least about 40% (atomic) N, and resides closer to the dielectric than the nitrogen-poor portion. The nitrogen-poor portion has a composition of less than about 30% (atomic) N (e.g., between about 5-30% N) and resides in contact with the metal, e.g., copper. The diffusion barrier film can also include a layer of titanium residing between the layer of dielectric and the layer of compositionally graded titanium nitride. The layer of titanium is often partially or completely converted to titanium oxide upon contact with a dielectric layer. The barrier film having a compositionally graded titanium nitride layer provides excellent diffusion barrier properties, exhibits good adhesion to copper, and reduces uncontrolled diffusion of titanium into interconnects.