A semiconductor package includes a first package substrate, a first semiconductor chip on the first package substrate, a plurality of first chip connection units to connect the first package substrate to the first semiconductor chip, an interposer on the first semiconductor chip, the interposer having a width greater than a width of the first semiconductor chip in a direction parallel to an upper surface of the first package substrate, and an upper filling layer including a center portion and an outer portion, the center portion being between the first semiconductor chip and the interposer, and the outer portion surrounding the center portion and having a thickness greater than a thickness of the center portion in a direction perpendicular to the upper surface of the first package substrate.