Copper adhesion promoters for polyimide: Heterocyclic compounds additives containing amino and hydroxyl groups

Fan Out Wafer Level Packaging (FOWLP) has been applied for various types of semiconductor devices, such as power controller, RF device, and application processor of smart phone. However, issues of adhesion on the interface between polyimide (PI) and Cu in redistribution layers (RDL) of FOWLP remain unsolved. In this study, we conducted a comparative study to improve the adhesion strength of PI to Cu and realize higher reliability by utilizing two heterocyclic compounds additives containing amino and hydroxyl groups as adhesion promoters. First, the effect of adhesion promoters on interfacial adhesion strength between Cu and PI were quantitatively measured by peel test. Second, the mechanical, thermal and dielectric properties of the as-synthesized PI films were measured. The results proved that the heterocyclic compounds additives of DHP and DAHP could be excellent candidates for Cu adhesion promoters of PI, and the as-synthesized PI film also proved excellent mechanical, thermal and dielectric properties.