The Effect of Electromigration and Stress Migration on NT-Cu RDLs Passivated with Titanium Dioxide

Due to the shrinking size of chip devices, the current density carried by redistribution layer (RDLs) increases. We used titanium dioxide (TiO
2
) as the passivation layer to enhance the lifetime of electro migration. The lifetime of TiO
2
-capped NT-Cu RDLs increased about 2 times compared to those coated with polyimide (PI). In this study, we found the mechanism of failure on NT-Cu RDLs capped with TiO
2
was the electro migration-induced voiding combined with the stress migration.