A method for forming through vias comprises the steps of forming a dielectric layer over a package and forming an RDL over the dielectric layer, wherein forming the RDL includes the steps of forming a seed layer, forming a first patterned mask over the seed layer, and performing a first metal plating. The method further includes forming through vias on top of a first portion of the RDL, wherein forming the through vias includes forming a second patterned mask over the seed layer and the RDL, and performing a second metal plating. The method further includes attaching a chip to a second portion of the RDL, and encapsulating the chip and the through vias in an encapsulating material.