Ruthenium Barrier/Seed Layer for Cu/Low-κ Metallization

Ru is examined as a barrier/seed layer in different layer stacks, with and without Ta, for a Cu/low-κ system. Ru was found to promote a more pronounced Cu(111) texture than Ta, and the texturing appears to increase with the increase of the Ru-layer thickness. Physical-vapor-deposited Cu films on both Ru and layers are adequately smooth with root–mean–square roughness of . Ru crystals on a low-κ layer have a columnar microstructure. Cu and Ru diffusion into the low-κ occurred after thermal annealing at for . A four-point bend adhesion study demonstrates a sufficiently high Ru/low-κ adhesion strength in comparison to Ta/low-κ .