Ascorbic Acid-Assisted Self-Assembly of 4-Aminothiophenol to Enhance Interfacial Adhesion between Copper and Ajinomoto Build-up Film

High-speed data transmission requires the formation of fine and smooth Cu wiring, which inevitably causes a decline of interfacial bonding strength between Cu and the insulating dielectric layer. In this work, 4-aminothiophenol (4-ATP) is used as a bifunctional promoter for the interfacial adhesion between a Cu foil and a widely used Ajinomoto build-up film (ABF) without coarsening the Cu surface. It is found that the introduction of ascorbic acid (AA) accelerates the self-assembly process of 4-ATP on Cu surface, as monitored by <i>in situ</i> attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and examined by cyclic voltammetry (CV). Peel strength tests and morphology analyses reveal that the AA-assisted 4-ATP SAM significantly enhances the interfacial adhesion between Cu and ABF, which is of practical significance in advanced packaging.