Through silicon via filling with suppression breakdown of PEG–Br^– in absence of accelerator

The effects of halide ions on the adsorption of polyethylene glycol (PEG) and through-silicon via (TSV) filling were investigated. Halide ions on a Cu surface assist the adsorption of PEG, and the suppression effect of PEG–halide ion layers increases in the order of Cl^– < Br^– < I^-. For all halide ions, suppression breakdown and negative differential resistance were observed, suggesting that the three halide ions with PEG potentially induce Cu bottom-up filling. However, we confirmed that only Br^- enables Cu bottom-up filling, whereas Cl^– results in conformal deposition and I^– cannot complete bottom-up filling due to the low Faradaic efficiency. The PEG-Br^– provides sufficient suppression strength, facilitating the formation of passive–active regions and enabling defect-free Cu filling without an accelerator. This study indicates that the property of the suppression layer contributes significantly to Cu bottom-up filling based on a passive–active filling mechanism.