An Approach to the Development of Organic Additives for Electrodeposition of Narrow Copper Interconnects

We have characterized the electrochemical properties and wetting effects of various organic materials, including selected accelerators, suppressors, and wetters, for the electrodeposition of submicrometer-wide copper interconnects. An additive composition consisting of the following organic chemicals was tested: bis(3-sulfopropyl)-disulfide, disodium salt as an accelerator, polyethylene glycol as a suppressor, and a cross-linked polyamide as a second suppressor (working also as a wetter). Copper films plated using this makeup exhibited a surface roughness of ∼35 nm after annealing, with grain sizes on the order of 0.1-0.5 μm, and an electrical resistivity of ∼ 1.9 μΩ cm. Using this made-up solution, 120 nm wide trenches were successfully gap-filled.