A semiconductor package includes a first sub-semiconductor device, an interposer, and a second sub-semiconductor device stacked on each other, and a heat sink covering the second sub-semiconductor device. The first sub-semiconductor device includes a first substrate and a first semiconductor chip. The interposer includes a dielectric layer, a thermal conductive layer in contact with a bottom surface of the dielectric layer, a first thermal conductive pad in contact with a top surface of the dielectric layer, and thermal conductive vias penetrating the dielectric layer to connect the thermal conductive layer to the first thermal conductive pad. A bottom surface of the thermal conductive layer is adjacent to and connected to a top surface of the first semiconductor chip. The second sub-semiconductor device is disposed on the dielectric layer without overlapping the first thermal conductive pad. The heat sink further covers the first thermal conductive pad to be connected thereto.