A semiconductor package with improved thermal properties is provided. The semiconductor package includes a first package including a first die, an interposer on the first package and including a first area and a second area. A second package is on a top face of the interposer in the second area, and a thermal diffusion structure is on a top face of the interposer in the first area. The thermal diffusion structure is configured so that heat generated in the first die is discharged through the thermal diffusion structure.