Polyethylene Glycol-Based Single Organic Additive for Through Silicon Via Filling and its Structural Modification Effect

In this study, a polyethylene glycol-based organic additive, with quaternary ammonium cation functional groups linked to a naphthalene rings at both ends was synthesized, for through silicon via (TSV) filling. The synthesized additive strongly suppressed Cu electrodeposition under convection and successfully bifurcated the deposition surface of TSVs into active and passive regions, allowing defect-free TSV filling. However, there was a variation in TSV filling uniformity depending on the additive chain length. The chain length was adjusted using polyethylene glycol of various molecular weights as a starting material for the additive. The electrochemical investigation revealed that the chain length was related to the re-adsorption rate during Cu electrodeposition, which is critical in TSV filling. At the optimal chain length, uniform and defect-free bottom-up TSV filling was successfully achieved and TSV filling time was reduced to 500 s.