A semiconductor device includes at least first and second semiconductor chips stacked on each other along a first direction, at least one through-silicon-via (TSV) through at least the first semiconductor chip of the first and second semiconductor chips, a contact pad on the at least one TSV of the first semiconductor chip, the contact pad electrically connecting the TSV of the first semiconductor chip to the second semiconductor chip, and a plurality of dummy pads on the first semiconductor chip, the plurality of dummy pads being spaced apart from each other and from the contact pad along a second direction, and the dummy pads having same heights as the contact pads as measured between respective top and bottom surfaces along the first direction.