A semiconductor package includes a package substrate, a semiconductor chip on the package substrate, and a plurality of underfills between the package substrate and the semiconductor chip. The package substrate includes a trench formed in the package substrate and a plurality of dams on both sides of the trench, respectively. The top surfaces of the plurality of dams may be positioned at a lower level than the bottom surface of the semiconductor chip in a cross-sectional view of the semiconductor package with the package substrate providing a base reference level.