Influence of surface properties on adhesion strength of dielectric passivation in chip size packaging

This study focuses on adhesion strength of the dielectric passivation for RDL (Redistribution Layer) process in CSP (Chip Size Packaging). The relationship between the surface state and the adhesion of the dielectric passivation was investigated. Dielectric passivation is a layer for protecting the wiring, and adhesion to the base substrate surface and the wiring material surface is important. To improve the adhesion strength, it is necessary to grasp factors that affect the adhesion strength. Surface properties of substrates such as mechanical and chemical properties were investigated before and after the dielectric passivation forming process. In the case of using the organic dielectric passivation, it was revealed that metal and fluorine residues after RDL formation were the main factor to weaken the adhesion strength. To remove these residues, argon plasma treatment was found to be effective. In addition, adhesion strength was also improved. The CSP applied with argon plasma treatment passed the reliability test. It was thought that the improvement of adhesion strength might make large contribution to it.