A semiconductor device is provided. The semiconductor device includes a base substrate, a die stacking unit, a number of dummy micro bumps, and an underfill material. The die stacking unit, which is mounted on the base substrate, includes a first die, a second die, and a number of first conductive joints. The first die and the second die are stacked on each other, and the first conductive joints are disposed between and connected to the first die and the second die. The dummy micro bumps, which are disposed between the first conductive joints, are connected to the first die but not to the second die. The underfill material is filled into a number of gaps between the base substrate, the first die, the second die, the first conductive joints, and the dummy micro bumps.