Abstract:
Barrier layers, barrier stacks, and seed layers for small-scale interconnects (e.g., copper) are combinatorially screened using test structures sputtered or co-sputtered through apertures of varying size. Various characteristics (e.g., resistivity, crystalline morphology, surface roughness) related to conductivity, diffusion blocking, and adhesion are measured before and/or after annealing and compared to arrive at materials and process parameters for low diffusion with high conductivity through the interconnect. Example results show that some formulations of tantalum-titanium barriers may replace thicker tantalum/tantalum-nitride stacks, in some cases with a Cu—Mn seed layer between the Ta—Ti and copper.
Abstract:
Barrier layers, barrier stacks, and seed layers for small-scale interconnects (e.g., copper) are combinatorially screened using test structures sputtered or co-sputtered through apertures of varying size. Various characteristics (e.g., resistivity, crystalline morphology, surface roughness) related to conductivity, diffusion blocking, and adhesion are measured before and/or after annealing and compared to arrive at materials and process parameters for low diffusion with high conductivity through the interconnect. Example results show that some formulations of tantalum-titanium barriers may replace thicker tantalum/tantalum-nitride stacks, in some cases with a Cu—Mn seed layer between the Ta—Ti and copper.
Abstract:
A barrier film including at least one ferromagnetic metal (e.g., nickel) and at least one refractory metal (e.g., tantalum) effectively blocks copper diffusion and facilitates uniform contiguous (non-agglomerating) deposition of copper layers less than 100 Å thick. Methods of forming the metal barrier include co-sputtering the component metals from separate targets. Using high-productivity combinatorial (HPC) apparatus and methods, the proportions of the component metals can be optimized. Gradient compositions can be deposited by varying the plasma power or throw distance of the separate targets.