Investigation of novel suppressor Nitrotetrazolium Blue chloride on cobalt superconformal growth

It is significantly important to develop novel suppressor to achieve cobalt superconformal filling. Linear sweeping voltammetry (LSV) and impedance spectra (EIS) were coupled together to study the effect of novel dye suppressor nitrotetrazolium blue chloride (NBT) on cobalt electrodeposition. The adsorption behavior of NBT on cobalt substrate was investigated by applying density functional theory (DFT) calculation, molecular dynamics (MD) simulation and in situ Raman spectra , while the interaction between NBT and cobalt ions (Co 2+ ) is analyzed based on topology analysis and interaction region indicator (IRI) analysis. Synergistic suppressing mechanism, namely adsorption effect and coordination effect, was proposed to explain the suppressing effect of NBT during cobalt electrodeposition. The cobalt surface morphology analysis under the influence of NBT demonstrates that NBT is of grain refinement, while XRD analysis indicates that the formation of Co hcp (100) is formed preferentially. The superconformal filling of cobalt is achieved in microvias with different diameters. The cobalt layer is of excellent quality due to low surface deposit thickness (SDT). The SDT values are 15.9 μm, 8.8 μm and 4.9 μm for 150 μm, 100 μm and 50 μm.