A semiconductor package includes a substrate and a flip-chip on the substrate The flip-chip includes first bump pads and second bump pads on an active surface of the flip-chip. Vias are disposed on the second bump pads. The first bump pads have a pad size that is smaller than that of the second bump pads. An underfill layer is disposed between the flip-chip and the substrate to surround the vias. The underfill layer is in direct contact with a surface of each of the first bump pads.