A semiconductor structure includes a first substrate; a second substrate, disposed over the first substrate; a die, disposed over the second substrate; a via, extending through the second substrate and electrically connecting to the die; a redistribution layer (RDL) disposed between the first substrate and the second substrate, including a dielectric layer, a first conductive structure electrically connecting to the via, and a second conductive structure laterally surrounding the first conductive structure; and an underfill material, partially surrounding the RDL, wherein one end of the second conductive structure exposed through the dielectric layer is entirely in contact with the underfill material.