Selective Filling and Sintering of Copper Nanoclusters for Interconnect

In copper interconnect technology, dielectric trenches are patterned, filled with copper, and polished. We report a cluster-based deposition technology that provides efficient trench filling and excellent selectivity between trenches and plateaus on damascene structures. The selectivity arises due to the propensity for reflection of clusters from the planar surfaces between trenches. Trenches of sub-200 nm widths, with various diffusion barriers and seed layers, and up to 5:1 aspect ratios have been completely filled with copper clusters. We also show that copper clusters can be sintered into a seed layer using hydrogen annealing. Thus, dense copper films within trenches are obtained. Preliminary results from planar samples show that the resistivity is around 2.3 times 10^-8 Omegam.