A Novel Leveler W-3: Synthesis and Application in Copper Electroplating for Microvia Filling

Levelers are critical additives in acid sulfate copper electroplating, profoundly influencing the quality of copper deposition in printed circuit boards and integrated circuit interconnects. This study synthesized a novel leveler, named W-3, via polymerization using tetraethylene glycol derivatives and 2-mercaptobenzothiazole as monomers. The molecular structure of W-3 was confirmed by 1 H nuclear magnetic resonance spectroscopy. Using a combination of electrochemical analyses and quantum chemical calculations, we systematically investigated W-3’s adsorption characteristics on copper surface and its impact on electrodeposition behavior. Results demonstrated that, compared to the conventional leveler Janus Green B (JGB), W-3 exhibited significantly stronger adsorption onto the copper surface and consequently provided greater inhibition of copper deposition. Microvia filling experiments revealed that employing W-3 achieved a microvia filling ratio of 91.1% after 60 min of plating, substantially exceeding the 80.2% filling ratio achieved with JGB under equivalent conditions. This confirms W-3’s superior filling efficiency. Collectively, this work validates the significant application potential of W-3 as a high-performance leveler for microvia filling and provides a solid theoretical basis for designing novel electroplating additives.