A semiconductor device comprises a package substrate, a semiconductor chip, a plurality of bump electrodes and one or more dummy chips. The semiconductor chip is mounted on one surface of the package substrate. The bump electrodes are the other surface of the package substrate and electrically connected to the semiconductor chip through a wiring structure. Each of the dummy chips is mounted on a predetermined region close to a corner portion of the semiconductor chip on the one surface of the package substrate.
In the semiconductor chip, the dummy chips are formed of material having the same or similar coefficient of thermal expansion as that of the semiconductor chip. Therefore the stress caused by a difference between coefficients of thermal expansion is suppressed so as to improve connection reliability.