Effect of Dielectric Process on the Interfacial Adhesion of RDL for FOWLP

The effect of low-temperature curable polybenzoxazole (PBO) process conditions on the interfacial adhesion energies between PBO dielectric and Cu redistribution layer for advanced fan-out packaging (FO package) were systematically investigated. The interfacial adhesion energies were 13.8 ± 2.0, 21.7 ± 2.7, and 6.3 ± 0.4 J/m
²
under PBO curing temperature at 175, 200, and 225 °C, respectively. The X-ray photoelectron spectroscopy analysis showed that there exists a good correlation between the interfacial adhesion energy and the O 1s peak area fraction. Also, the nanoindentation analysis showed that there exists a little correlation between the interfacial adhesion energy and the hardness. Therefore, the optimized curing temperature of PBO must be carefully controlled to obtain interfacial adhesion of improvement to achieve interfacial reliability for advanced FO package.