Synthesis and Evaluation of Novel Nitrogen-Containing Aromatic Heterocyclic Compounds as Levelers for Copper Electroplating

Nitrogen-containing aromatic heterocyclic compounds have gained considerable attention as levelers for copper electroplating in electronics manufacturing. However, research on synthesizing novel leveler molecules to improve the filling capability of blind vias remains limited. In this study, two novel nitrogen-containing heterocyclic benzyl quaternary ammonium compounds, designated as Leveler 1 (benzyl-pyridinium chloride) and Leveler 2 (benzyl-pyrrolinium chloride), were successfully synthesized and evaluated as levelers for blind via filling in high-density interconnect printed circuit boards (PCBs). Electrochemical evaluations revealed that the pyridine-based Leveler 1 exhibited superior inhibitory effects compared to the pyrrole-based Leveler 2. Quantum chemical calculations and molecular dynamics simulations confirmed the enhanced adsorption performance of the pyridine-based compound on the copper surface. Electroplating filling experiments and thermal stress testing were conducted to evaluate the practical applicability of the leveler compounds. The results show that a pyridine-based compound as a leveler effectively facilitates reliable superfilling of copper in blind vias. These findings suggest that benzyl-pyridinium chloride (Leveler 1), featuring a six-membered pyridine ring, exhibits excellent performance as a leveler for blind via copper filling and holds great promise as a novel additive for this application.