Simulating Cu electrodeposition in high aspect ratio features: Effect of control mode and uncompensated resistance in S-NDR systems

Void-free Cu electrodeposition in high aspect ratio features requires, at a minimum, an additive package containing micromolar halide and polyether that combine to form co-adsorbed adlayer inhibits metal deposition on the electrode interface. Successful feature filling relies preferential growth proceeding from most recessed surfaces where sustained breakdown of polyether-halide suppressor layer occurs. Localization is result positive feedback between inhibitor subject transport limitations precursor(s). This gives rise S-shaped negative differential resistance (S-NDR) that, convolved with uncompensated ohmic resistance, results bifurcation into active passive zones. The interplay derived S-NDR behavior, cell potentiostatic regulation explored comparison galvanostatic filling. Uncompensated arises working contact electrolyte reference electrodes. For CuSO4 – H2SO4 80 µmol/L Cl? 40 polyether, simulations minimal reveal narrow window fully voided filling; bottom-up terminates prematurely even under favorable conditions. In contrast, optimized operation enables void-free termination dictated by coulometry. Increasing along application accordingly more applied potentials produces dynamics blend attributes enable complete, spontaneous passivation near opening. Importantly, these beneficial effects are also evident for trench arrays having variable widths or heights.