Direct Laser Patterning using Excimer Laser on Polyimide Compositions with Low Dielectric Properties and Good Flexibility for Redistribution Layer

Advanced package technology requires finer redistribution layer (RDL) on organic interposer. However, with the conventional semi additive process (SAP), it is difficult to solve miniaturization issues. One of this reason is that organic materials are difficult to achieve both photosensitivity and material properties such as insulation and heat resistance. Direct laser patterning using KrF excimer laser is effective method for miniaturization because insulating material does not need to be photosensitive, so it can focus on improving the material properties. And KrF excimer laser has advantage for finer patterning due to short wavelength.Also, vias and trenches can be formed simply by changing masks and direct laser patterning. Therefore, it is possible to apply the dual damascene process. This method not only achieves miniaturization, but also reduces the number of process steps compared to SAP.This time, we used this method to form patterns on polyimide compositions for RDL. After patterning, the prototype layer was plated with Cu, and then processed Cu/polymer hybrid CMP.